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[ { "abstract": "We present a study of electric field effect on the efficiency of GaN/In0.1Ga0.9N p i n solar cells by using the advanced physical models of semiconductor devices (APSYS) simulation program. In this study, the electric field strength and other parameters such as optimum thickness of p type layer and efficiency of GaN/In0.1Ga0.9N p i n solar cells with different i layer thicknesses have been performed. On the basis of simulating results, for a high efficiency solar cell, it is found that the optimum p type layer concentration is above 4x1016 cm 3 and the suitable thickness is between 0.1 to 0.2 mm. For different i layer thickness and p doping concentrations, a critical electric field (Fc) has been found at 100 kV/cm. It is worth to note that when the electric field strength of i layer below Fc value, the solar cell efficiency will dramatically decrease. Thus Fc can be seen as an index for acquiring the quality of solar device.", "author_names": [ "Der-Yuh Lin", "Chao Yu Chi" ], "corpus_id": 108453953, "doc_id": "108453953", "n_citations": 0, "n_key_citations": 0, "score": 2, "title": "Critical Electric Field of InGaN p i n Solar Cell", "venue": "", "year": 2013 }, { "abstract": "The photovoltaic characteristics of Ga face GaN/InGaN p i n solar cells are investigated numerically. The severe polarization and barrier effects induced by the GaN/InGaN hetero interfaces are demonstrated to be detrimental for the carrier collection. The conversion efficiency could be degraded to be out of application when the degree of polarization and/or indium composition are high. To efficiently eliminate both critical issues, the solar cell structure with appropriate band engineering is introduced. In the proposed structure, the photovoltaic characteristics not only show high grade performance but also become insensitive to the degree of polarization, even in the situation of high indium composition.", "author_names": [ "Jih-Yuan Chang", "Shih-Hsun Yen", "Yi-An Chang", "Yen-Kuang Kuo" ], "corpus_id": 33498566, "doc_id": "33498566", "n_citations": 24, "n_key_citations": 0, "score": 0, "title": "Simulation of High Efficiency GaN/InGaN p i n Solar Cell With Suppressed Polarization and Barrier Effects", "venue": "IEEE Journal of Quantum Electronics", "year": 2013 }, { "abstract": "Photons In, Electrons Out: Basic Principles of PV Electrons and Holes in Semiconductors Generation and Recombination Junctions Analysis of the p n Junction Monocrystalline Solar Cells Thin Film Solar Cells Managing Light Over the Limit: Strategies for Higher Efficiency.", "author_names": [ "J Roy Nelson" ], "corpus_id": 117097776, "doc_id": "117097776", "n_citations": 2054, "n_key_citations": 184, "score": 0, "title": "The physics of solar cells", "venue": "", "year": 2003 }, { "abstract": "In order to find an upper theoretical limit for the efficiency of p n junction solar energy converters, a limiting efficiency, called the detailed balance limit of efficiency, has been calculated for an ideal case in which the only recombination mechanism of hole electron pairs is radiative as required by the principle of detailed balance. The efficiency is also calculated for the case in which radiative recombination is only a fixed fraction fc of the total recombination, the rest being nonradiative. Efficiencies at the matched loads have been calculated with band gap and fc as parameters, the sun and cell being assumed to be blackbodies with temperatures of 6000degK and 300degK, respectively. The maximum efficiency is found to be 30% for an energy gap of 1.1 ev and fc 1. Actual junctions do not obey the predicted current voltage relationship, and reasons for the difference and its relevance to efficiency are discussed.", "author_names": [ "William Shockley", "Hans J Queisser" ], "corpus_id": 121565455, "doc_id": "121565455", "n_citations": 8906, "n_key_citations": 211, "score": 0, "title": "Detailed Balance Limit of Efficiency of p n Junction Solar Cells", "venue": "", "year": 1961 }, { "abstract": "The impact of the polarization compensation InGaN interlayer between the heterolayers of Ga face GaN/InGaN p i n solar cells is investigated numerically. Because of the enhancement of carrier collection efficiency, the conversion efficiency is improved markedly, which can be ascribed to both the reduction of the polarization induced electric field in the InGaN absorption layer and the mitigation of potential barriers at heterojunctions. This beneficial effect is more remarkable in situations with higher polarization, such as devices with a lower degree of relaxation or devices with a higher indium composition in the InGaN absorption layer.", "author_names": [ "Jih-Yuan Chang", "Bo Ting Liou", "Han-Wei Lin", "Ya-Hsuan Shih", "Shu-Hsuan Chang", "Yen-Kuang Kuo" ], "corpus_id": 43693570, "doc_id": "43693570", "n_citations": 19, "n_key_citations": 1, "score": 0, "title": "Numerical investigation on the enhanced carrier collection efficiency of Ga face GaN/InGaN p i n solar cells with polarization compensation interlayers.", "venue": "Optics letters", "year": 2011 }, { "abstract": "The advantages of a (0001) face GaN/InGaN p i n solar cell with compositional grading configuration between i InGaN/p GaN layers are studied numerically. With the use of the grading layer, the conversion efficiency is markedly promoted due to the reduction of potential barrier height for holes and due to the decrease of polarization. Optimized conversion efficiency is obtained when the thickness of the grading layer increases to a critical value. This critical thickness is strongly influenced by the polarization charges and doping concentration of the grading layer. When the density of the polarization charges is high or the doping concentration is low, a thick grading layer is required to achieve high efficiency.", "author_names": [ "Yen-Kuang Kuo", "B C Lin", "Jih-Yuan Chang", "Fangming Chen", "H C Kuo" ], "corpus_id": 36166178, "doc_id": "36166178", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Numerical Study of (0001) Face GaN/InGaN p i n Solar Cell With Compositional Grading Configuration", "venue": "IEEE Photonics Technology Letters", "year": 2012 }, { "abstract": "The influence of piezoelectric polarization on the performance of p on n (0001) face GaN/InGaN p i n solar cells is investigated. Simulation results show that the energy band is tilted into the direction detrimental for carrier collection due to the polarization induced electric field. When the indium composition of InGaN layer increases, this unfavorable effect becomes more serious which, in turn, deteriorates the device performance. This discovery demonstrates that, besides the issue of crystal quality, the problem caused by the polarization effect needs to be overcome for the development of GaN based solar cells.", "author_names": [ "Jih-Yuan Chang", "Yen-Kuang Kuo" ], "corpus_id": 8396000, "doc_id": "8396000", "n_citations": 41, "n_key_citations": 3, "score": 0, "title": "Numerical Study on the Influence of Piezoelectric Polarization on the Performance of p on n (0001) Face GaN/InGaN p i n Solar Cells", "venue": "IEEE Electron Device Letters", "year": 2011 }, { "abstract": "Abstract The solar power conversion efficiency of compositionally graded In x Ga 1 x N solar cells was simulated using a finite element approach. Incorporating a compositionally graded region on the InGaN side of a p GaN/n In x Ga 1 x N heterojunction removes a barrier for hole transport into GaN and increases the cell efficiency. The design also avoids many of the problems found to date in homojunction cells as no p type high In content region is required. Simulations predict 28.9% efficiency for a p GaN/n In x Ga 1 x N/n In 0.5 Ga 0.5 N/p Si/n Si tandem structure using realistic material parameters. The thickness and doping concentration of the graded region was found to substantially affect the performance of the cells.", "author_names": [ "Gregory V Brown", "Joel W Ager", "Wladek Walukiewicz", "Junqiao Wu" ], "corpus_id": 16908615, "doc_id": "16908615", "n_citations": 188, "n_key_citations": 14, "score": 0, "title": "Finite element simulations of compositionally graded InGaN solar cells", "venue": "", "year": 2010 }, { "abstract": "Excitonic solar cells1 including organic, hybrid organic inorganic and dye sensitized cells (DSCs) are promising devices for inexpensive, large scale solar energy conversion. The DSC is currently the most efficient2 and stable3 excitonic photocell. Central to this device is a thick nanoparticle film that provides a large surface area for the adsorption of light harvesting molecules. However, nanoparticle DSCs rely on trap limited diffusion for electron transport, a slow mechanism that can limit device efficiency, especially at longer wavelengths. Here we introduce a version of the dye sensitized cell in which the traditional nanoparticle film is replaced by a dense array of oriented, crystalline ZnO nanowires. The nanowire anode is synthesized by mild aqueous chemistry and features a surface area up to one fifth as large as a nanoparticle cell. The direct electrical pathways provided by the nanowires ensure the rapid collection of carriers generated throughout the device, and a full Sun efficiency of 1.5% is demonstrated, limited primarily by the surface area of the nanowire array.", "author_names": [ "Matt Law", "Lori E Greene", "Justin C Johnson", "Richard J Saykally", "Peidong Yang" ], "corpus_id": 37360993, "doc_id": "37360993", "n_citations": 4793, "n_key_citations": 36, "score": 0, "title": "Nanowire dye sensitized solar cells", "venue": "Nature materials", "year": 2005 }, { "abstract": "A device physics model has been developed for radial p n junction nanorod solar cells, in which densely packed nanorods, each having a p n junction in the radial direction, are oriented with the rod axis parallel to the incident light direction. High aspect ratio (length/diameter) nanorods allow the use of a sufficient thickness of material to obtain good optical absorption while simultaneously providing short collection lengths for excited carriers in a direction normal to the light absorption. The short collection lengths facilitate the efficient collection of photogenerated carriers in materials with low minority carrier diffusion lengths. The modeling indicates that the design of the radial p n junction nanorod device should provide large improvements in efficiency relative to a conventional planar geometry p n junction solar cell, provided that two conditions are satisfied: (1) In a planar solar cell made from the same absorber material, the diffusion length of minority carriers must be too low to allow for extraction of most of the light generated carriers in the absorber thickness needed to obtain full light absorption. (2) The rate of carrier recombination in the depletion region must not be too large (for silicon this means that the carrier lifetimes in the depletion region must be longer than ~10 ns) If only condition (1) is satisfied, the modeling indicates that the radial cell design will offer only modest improvements in efficiency relative to a conventional planar cell design. Application to Si and GaAs nanorod solar cells is also discussed in detail.", "author_names": [ "Brendan M Kayes", "Harry A Atwater", "Nathan S Lewis" ], "corpus_id": 8225589, "doc_id": "8225589", "n_citations": 1255, "n_key_citations": 25, "score": 0, "title": "Comparison of the device physics principles of planar and radial p n junction nanorod solar cells", "venue": "", "year": 2005 } ]

[ { "abstract": "A spin based logic device is proposed. It is comprised of a common free ferromagnetic layer and four discrete ferromagnetic nanopillars, each containing an independent fixed layer. It has the functionality of a majority gate and is switched via motion of domain walls by spin transfer torque. Validity of its logic operation and a quantitative performance prediction are demonstrated by micromagnetic simulation. It is entirely compatible with complimentary metal oxide semiconductor technology.", "author_names": [ "Dmitri E Nikonov", "George Bourianoff", "Tahir Ghani" ], "corpus_id": 45264246, "doc_id": "45264246", "n_citations": 131, "n_key_citations": 5, "score": 1, "title": "Proposal of a Spin Torque Majority Gate Logic", "venue": "IEEE Electron Device Letters", "year": 2011 }, { "abstract": "A novel scheme for non volatile digital computation is proposed using spin transfer torque (STT) and automotion of magnetic domain walls (DWs) The basic computing element is composed of a lateral spin valve (SV) with two ferromagnetic (FM) wires served as interconnects, where DW automotion is used to propagate the information from one device to another. The non reciprocity of both device and interconnect is realized by sizing different contact areas at the input and the output as well as enhancing the local damping mechanism. The proposed logic is suitable for scaling due to a high energy barrier provided by a long FM wire. Compared to the scheme based on non local spin valves (NLSVs) in the previous proposal, the devices can be operated at lower current density due to utilizing all injected spins for local magnetization reversals, and thus improve both energy efficiency and resistance to electromigration. This device concept is justified by simulating a buffer, an inverter, and a 3 input majority gate with comprehensive numerical simulations, including spin transport through the FM/non magnetic (NM) interfaces as well as the NM channel and stochastic magnetization dynamics inside FM wires. In addition to digital computing, the proposed framework can also be used as a transducer between DWs and spin currents for higher wiring flexibility in the interconnect network.", "author_names": [ "Sou-Chi Chang", "Sasikanth Manipatruni", "Dmitri E Nikonov", "Ian A Young", "Azad Naeemi" ], "corpus_id": 15771702, "doc_id": "15771702", "n_citations": 1, "n_key_citations": 1, "score": 0, "title": "Low power Spin Valve Logic using Spin transfer Torque with Automotion of Domain Walls", "venue": "ArXiv", "year": 2016 }, { "abstract": "devices find their main application in non volatile memories, namely magnetic random access memory (MRAM) Recently, magnetic memory based on switching by injection of spin polarized current, spin transfer torque RAM (STTRAM) [1] proved to be many times more efficient than previous types of MRAM. It is natural to extend the physics of spintronics to logic devices [2] The expected benefits are reconfigurable and non volatile logic, which does not suffer from standby power dissipation and can be turned on instantly. In spite of numerous spintronic logic devices proposed, few of them have been fabricated and none were demonstrated to function in an integrated circuit. A spin logic device, a spin torque majority gate (STMG) has been proposed [3,4] which leverages well developed processes and materials used in STTRAM. In the present work we reveal the character of magnetization dynamics in switching of this device, describe the operation of a practically important circuit, a one bit of a full adder, and obtain performance projections for it. These results support feasibility of experimental implementation of STMG, demonstrate the possibility of creating extended spintronic circuits (e.g. adders) without the need of spin to electrical conversion, and provide an argument that such circuits can have performance comparable with the incumbent CMOS technology. Fig 1. Layout of STMG. Input nanopillars are \"A\" \"B\" and \"C\" output pillar is \"Out\" in the middle. Minimum width is", "author_names": [ "Dmitri E Nikonov", "George Bourianoff", "Tahir Ghani", "Ian A Young" ], "corpus_id": 109834783, "doc_id": "109834783", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Nanomagnetic Logic and Magnetization Switching Dynamics in Spin Torque Majority Gates", "venue": "", "year": 2012 }, { "abstract": "In recent years, spin orbit torques induced by charge current in heavy metal/magnetic structures have attracted wide attention among researchers. Since the experimental demonstration of spin orbit torques due to the spin Hall effect (SHE) being able to manipulate the magnetization direction in an in plane MTJ structure[1] it has been heavily explored for applications in memory and logic. It provides a potential low power alternative to other techniques such as spin transfer torque or electric field control for magnetization reversal. Recently, it has been shown that the spin Hall effect can provide a clocking mechanism for logic applications where the spin Hall effect is used to change the magnetization of a perpendicularly magnetized device along the hard axis (in the plane of the film)[2] In [2] a series of three nanomagets are spaced closely together so they interact through dipole interactions. Each nanomagnet serves as a logic bit. An additional nearby magnet is used as the input. However, due to the dipole interactions, only logic states of 101 or 010 can be obtained. For logic applications, it would be beneficial to be able to individually control the states of the individual bits to obtain a full range of logic functions.", "author_names": [ "A K Smith", "Mahdi Jamali", "Daniel Hickox-Young", "Z Zhao", "Jing Wang" ], "corpus_id": 43491625, "doc_id": "43491625", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design and fabrication of nanomagnetic majority logic gate based on spin hall assisted switching", "venue": "2015 IEEE Magnetics Conference (INTERMAG)", "year": 2015 }, { "abstract": "Spin torque majority gate (STMG) is one of the promising options for beyond complementary metal oxide semiconductor logic. Improvement of its performance switching speed vs. required current is critical for its competitiveness. In this paper, (a) we identify an optimized layout of the gate comprised of thin magnetic wires with in plane magnetization; (b) we optimize geometries of perpendicular magnetization spin torque majority gates. Micromagnetic simulations demonstrate an improvement in switching current for in plane magnetization (with less than 1 ns switching time) from 6 mA in the original scheme to 1.5 mA in the present one. Additionally, failures of switching caused by vortex formation are eliminated and desired output magnetization is achieved. Various geometries of STMG with perpendicular magnetization are explored. The scheme with a straight cross proves to be the most advantageous. It is predicted to operate with the switching current of 50 mA and less than 4 ns switching time.", "author_names": [ "Dmitri E Nikonov", "Sasikanth Manipatruni", "Ian A Young" ], "corpus_id": 121854881, "doc_id": "121854881", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Switching efficiency improvement in spin torque majority gates", "venue": "", "year": 2014 }, { "abstract": "As scaling CMOS devices is approaching its fundamental limits, a new direction of research has emerged to study beyond CMOS spintronic devices that use electronic spin as their state variable, offering new and enhanced functionalities. Due to low operating voltage, non volatility, and efficient implementation of majority gate, a novel spin based device, all spin logic (ASL) has been widely studied for applications including interconnects [1] pattern recognition systems [2] and Boolean gates [3] However, ASL relies on a non local spin valve (NLSV) structure with the connection to ground being close to the input magnet to ensure non reciprocity. Thus, a large fraction of injected spins is shunted to ground without ever reaching the output magnet. In addition, supply clocking is envisioned to reduce energy dissipation [3] Even then, a 32 bit addition by ASL compared to that by CMOS, requires 5 orders of magnitude more energy. In this paper, we propose a novel device that uses voltage controlled strain mediated magnetization switching [4] and spin transfer torque (STT) to perform the first and second 900 of switching, respectively. The STT is created in a conventional spin valve instead of the NLSV structure used in ASL. Hence, the wasteful shunt path to ground is eliminated. Non reciprocity is ensured through a clocking scheme in which the input and output magnets are oriented along the stable easy axis and the meta stable saddle point of energy profile, respectively. It has been shown that the deterministic switching of a magnet from a saddle point is more efficient in terms of delay and energy and affected less by thermal noise [5] [6] The device can be cascaded in a domino logic scheme, Fig. 1 a, by performing the first 900 switching for all cascaded logic gates simultaneously; therefore, the overall delay of a more complicated circuit like a 32 bit adder significantly improves.", "author_names": [ "Rouhollah Mousavi Iraei", "Sourav Dutta", "Sasikanth Manipatruni", "Dmitri E Nikonov", "Ian A Young", "John T Heron", "Azad Naeemi" ], "corpus_id": 30747658, "doc_id": "30747658", "n_citations": 8, "n_key_citations": 2, "score": 0, "title": "A proposal for a magnetostriction assisted all spin logic device", "venue": "2017 75th Annual Device Research Conference (DRC)", "year": 2017 }, { "abstract": "Spin torque majority gate (STMG) is one of the promising options for beyond complementary metal oxide semiconductor non volatile logic circuits for normally off computing. Modeling of prior schemes demonstrated logic completeness using majority operation and nonlinear transfer characteristics. However significant problems arose with cascade ability and input output isolation manifesting as domain walls (DWs) stopping, reflecting off ends of wires or propagating back to the inputs. We introduce a new scheme to enable cascade ability and isolation based on (a) in plane DW automotion in interconnects, (b) exchange coupling of magnetization between two FM layers, and (c) 'round about' topology for the majority gate. We performed micro magnetic simulations that demonstrate switching operation of this STMG scheme. These circuits were verified to enable isolation of inputs from output signals and to be cascade able without limitations.", "author_names": [ "Dmitri E Nikonov", "Sasikanth Manipatruni", "Ian A Young" ], "corpus_id": 110490334, "doc_id": "110490334", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "Cascade able spin torque logic gates with input output isolation", "venue": "", "year": 2015 }, { "abstract": "A new digital device scheme based on the magnetoelectric coupling and automotion of the magnetic domain wall is proposed. A single device is composed of a ferromagnetic wire and two ferroelectric capacitors served as the input and the output. It is shown that with the initialization in the magnetic states, a single device and the corresponding majority gate can realize the NOT, NAND, and NOR functions. Furthermore, the device has the cascadability, input output isolation, gain, and nonreciprocity. The device concepts are justified by the numerical calculation, including the Landau Lifshitz Gilbert equation for the magnetization dynamics, the Landau Khalatnikov equation for the electric polarization dynamics, and the electrostatic equations for the open circuit output voltage and the charge sharing process between devices. The energy dissipation is also quantified and shown to be two to three orders of magnitude less than that in spin torque driven devices.", "author_names": [ "Sou-Chi Chang", "Sasikanth Manipatruni", "Dmitri E Nikonov", "Ian A Young" ], "corpus_id": 14531597, "doc_id": "14531597", "n_citations": 13, "n_key_citations": 3, "score": 0, "title": "Clocked Domain Wall Logic Using Magnetoelectric Effects", "venue": "IEEE Journal on Exploratory Solid State Computational Devices and Circuits", "year": 2016 }, { "abstract": "Spin based devices, in which information is carried via electron spin rather than electron charge, are potential candidates to complement CMOS technology due to the promise of non volatility and compact implementation of logic gates. One class of such devices is all spin logic (ASL) which is based on switching ferromagnets by spin transfer torque and conduction of spin polarized current. Using previously developed physics based circuit models for ASL, we develop a complete logic family for static ASL comprising of majority logic gates. We compare its performance metrics by means of circuit simulations using our Verilog A compact models. We also show the novel implementations of sequencing elements (e.g. latch and D flip flop) to enable clocked ASL. We also refine the models for ferromagnets to include spin relaxation inside ferromagnetic metals (FMs)", "author_names": [ "Vehbi Calayir", "Dmitri E Nikonov", "Sasikanth Manipatruni", "Ian A Young" ], "corpus_id": 25272248, "doc_id": "25272248", "n_citations": 47, "n_key_citations": 4, "score": 0, "title": "Static and Clocked Spintronic Circuit Design and Simulation With Performance Analysis Relative to CMOS", "venue": "IEEE Transactions on Circuits and Systems I: Regular Papers", "year": 2014 }, { "abstract": "We discuss the application of a novel class of device, the magneto electric magnetic tunnel junction (ME MTJ) to realize a variety of computational functions, including majority logic and the XNOR/XOR gate. We also develop a compact model to describe the operation of these devices, which function by utilizing the phenomenon of 'voltage controlled magnetism' to switch the operational state of MTJs. The model breaks down the switching process into three key stages of operation: electrical to magnetic conversion, magnetization transfer, and final state readout. Estimates for the switching energy and delay of these devices, obtained from this compact model, reveal significant improvements in both of these parameters when compared to conventional MTJs switched by spin transfer torque. In fact, the capacity to use the ME MTJ to implement complex logical operations within a single device allows its energy costs to even approach those of low power CMOS. The added benefits of non volatility and compact circuit footprint, combined with their potential for heterogeneous integration with CMOS, make the ME devices of considerable interest for post CMOS technology.", "author_names": [ "Nishtha Sharma", "Jonathan P Bird", "Peter A Dowben", "Andrew Marshall" ], "corpus_id": 100984216, "doc_id": "100984216", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Compact device model development for the energy delay analysis of magneto electric magnetic tunnel junction structures", "venue": "", "year": 2016 } ]

[ { "abstract": "Scatterometry is now an accepted technique for linewidth measurement in semiconductor manufacturing. To reduce the evaluation time when using real time optimization procedures, we introduce an effective medium approach to simulate the optical signatures of subwavelength line and space gratings. Such gratings behaves approximately like uniaxial crystals whose optical properties are completely described by two refractive indices. We propose an algebraic method for their calculation up to second order in pitch/wavelength for the extraordinary index, and up to 4th order in pitch/wavelength for the ordinary index. The formulas are valid for any angle of incidence and can be used with standard matrix formalism to calculate the optical properties of any arbitrary layer stack. We deduce the formulas for the indices. The comparison of effective medium calculations to rigorous coupled wave simulations for spectral measurements (polarized reflectometer and spectroscopic ellipsometer) shows excellent agreement. The sensitivity of scatterometry to tilt of the structures is very low for all measurement parameters except phase difference. It is shown that left and right tilt cannot be distinguished at all with spectral measurements with non conical incidence of light.", "author_names": [ "A Weidner", "Matthias Slodowski", "Christian Halm", "Claus Schneider", "Lothar Pfitzner" ], "corpus_id": 119823023, "doc_id": "119823023", "n_citations": 4, "n_key_citations": 0, "score": 1, "title": "Effective medium model for fast evaluation of scatterometric measurements on gratings", "venue": "SPIE Advanced Lithography", "year": 2004 }, { "abstract": "Abstract There is a strategic importance for the steel rolling industry to get a better understanding of the strip roll interaction to improve roll gap models, increase strip quality and decrease roll degradation. This requires roll gap sensors able to measure this interaction under industrial rolling conditions and in real time in order to propose a feed back control of process parameters. To reach these goals, this paper proposes a new roll gap friction sensor based on an inverse method that interprets optical fiber Bragg gratings (FBG) strain measurements under the roll surface (fully embedded) which enables to evaluate contact stresses with very short computation times, compatible with real time interpretation. This elastic inverse method is analytical and relies on plane strain and isothermal assumptions. The experimental apparatus is detailed, technical issues are clearly exposed as well as calibration procedures. Several pilot cold rolling tests have been performed at various rolling speeds and different strip thicknesses in order to demonstrate the industrial feasibility. Resulting evaluations of contact stresses are then compared with numerical simulations. Reasonable agreement is obtained for normal stress (i.e. pressure) but not for shear stress (only an order of magnitude is obtained)", "author_names": [ "D Weisz-Patrault", "L Maurin", "Nicolas Legrand", "Anas Ben Salem", "Abdelkebir Ait Bengrir" ], "corpus_id": 136500411, "doc_id": "136500411", "n_citations": 17, "n_key_citations": 2, "score": 0, "title": "Experimental evaluation of contact stress during cold rolling process with optical fiber Bragg gratings sensors measurements and fast inverse method", "venue": "", "year": 2015 }, { "abstract": "Many light field displays are fundamentally different from other displays in that they do not have quantized pixels, quantized angular outputs, or a physical screen position, which can make definitions and characterization problematic. We have determined that it is more appropriate to express the spatial resolution in terms of spatial cutoff frequency rather than a physical distance as in the case of a display with actual quantized pixels. This concept is then extended to also encompass angular resolution. The technique exploits the fact that when spatial resolution of a sinusoidal grating pattern is halved, its contrast ratio is reduced by a known proportion. An improved model, based on an earlier design concept, has been developed. It not only can be used to measure spatial and angular cutoff frequencies, but also can enable comprehensive characterization of the display. This model provides fast, simple measurement with good accuracy. It does not use special equipment or require time consuming subjective evaluations. Using the model to characterize images in a rapid, accurate manner validates the effectiveness of this technique.", "author_names": [ "Phil Surman", "Shizheng Wang", "Junsong Yuan", "Yuanjin Zheng" ], "corpus_id": 24396379, "doc_id": "24396379", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "One stop measurement model for fast and accurate tensor display characterization.", "venue": "Journal of the Optical Society of America. A, Optics, image science, and vision", "year": 2018 }, { "abstract": "With decreasing critical dimensions (CD) on lithography masks, increasing demands on CD metrology techniques come along. Already today the results of the three standard methods for CD measurements currently used, atomic force microscopy (AFM) scanning electron microscopy (SEM) and optical microscopy, typically do not yield the same results. This is because of, e.g. incomplete knowledge of the material parameters, insufficient modelling accuracy or especially in the case of optical microscopy insufficient resolution. With decreasing CDs these systematic differences increase. The need on new cross calibration strategies arises. Non imaging metrology methods like scatterometry as non destructive, non diffraction limited, fast optical methods offer access to the geometrical parameters of periodic structures like e.g. top and bottom CD, pitch, side wall angle, line height, or roughness. Therefore, these methods provide independently achieved additional information that can be used for cross calibration. At the PTB two scatterometers are in use (VIS l=633 nm and EUV l=13.55 nm) A third device (DUV l=193 nm) is under construction. It will offer a wide spectrum of measuring principles like scatterometry, ellipsometric scatterometry, reflectometry, polarisation reflectometry, and using a broadband light source spectroscopic ellipsometry and spectroscopic reflectometry. For simulation and modelling of the intensity distribution of the diffraction pattern two programs based on the rigorous coupled wave analysis (RCWA) method and a finite element method (FEM) respectively are used. The program features will be illustrated. A comparison of the simulations with the results achieved with the scatterometers on different types of lithography masks (chrome on glass, EUV masks) will be presented as well.", "author_names": [ "Matthias Wurm", "Bernd Bodermann", "Werner Mirande" ], "corpus_id": 136512251, "doc_id": "136512251", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Investigation and evaluation of scatterometric CD metrology methods", "venue": "SPIE Optical Metrology", "year": 2005 }, { "abstract": "The design and physical verification of contemporary integrated circuits is a challenging task due to their complexity. System in Package is an example of generally congested electronic components and interconnects which in the initial design process rely on computationally intensive electromagnetic simulations. Hence the available computer memory capacity and computational speed become meaningful limitations. An alternative method which allows the designer to overcome or reduce the limits is desired. This work represents the first demonstration of the application of effective medium theory to the analysis of those segments of the entire integrated system where the interconnect networks are more dense. The presented approach takes advantage of the deep subwavelength characteristic of interconnect structures. In order to achieve the aim of defining the homogeneous equivalent for the interconnect grating structure a few steps were followed towards proving the homogenisation concept and finally presenting it by an analytical formulation. A set of parameters (metal fill factor, aspect ratio, dielectric background and period to wavelength ratio) with values related to typical design rules were considered. Relating these parameters allows the empirical models to be defined. In order to show the relationship between existing effective medium theories and those developed in this Thesis, the presented empirical models are defined in terms of the Maxwell Garnett mixing rule with an additional scaling factor. The distribution of the scaling factor was analysed in terms of the calculated reflection and transmission coefficients of the homogenised structures that are equivalent to a given grating geometry. Finally the scaling factor, for each empirical model, was expressed by an analytical formula and the models validated by their application to the numerical analysis of grating structures. The numerical validation was carried out by comparing the reflection and transmission coefficients obtained for the detailed and homogenised structures. In order to ensure the empirical models can be broadly employed, the performance of the model in the presence of non normally incident plane wave was evaluated. For the range of angles 30o the model is accurate to 5% The impact of the shape of the grating, specifically the case of a tapered profile, typical of actual fabricated interconnects was also considered, with sidewall tapers of up to 5o giving the same error not higher than 5% Experimental validation of the application of the homogenisation concept to the analysis of interconnects is desired for two main applications: for the reflectivity estimation of a whole chip in a System in Package and for the performance estimation of interconnects on lower metal layers in an interconnect stack. For the first, free space measurements are taken of a grating plate with copper rods aligned in parallel illuminated by a plane wave in the X band (8.2 12.4 GHz) For the second, S parameters are measured for microstrip waveguides with a number of metal rods embedded in the substrate between the signal line and ground plane. The good agreement with the simulations validates the homogenisation approach for the analysis of interconnects.", "author_names": [ "Sonia M Holik" ], "corpus_id": 109369189, "doc_id": "109369189", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Application of effective medium theory to the analysis of integrated circuit interconnects", "venue": "", "year": 2010 }, { "abstract": "Diffraction based overlay (DBO) technologies have been developed to address the overlay metrology challenges for 22nm technology node and beyond. Most DBO technologies require specially designed targets that consist of multiple measurement pads, which consume too much space and increase measurement time. The traditional empirical approach (eDBO) using normal incidence spectroscopic reflectometry (NISR) relies on linear response of the reflectance with respect to overlay displacement within a small range. It offers convenience of quick recipe setup since there is no need to establish a model. However it requires three or four pads per direction (x or y) which adds burden to throughput and target size. Recent advances in modeling capability and computation power enabled mDBO, which allows overlay measurement with reduced number of pads, thus reducing measurement time and DBO target space. In this paper we evaluate the performance of single pad mDBO measurements using two 3D targets that have different grating shapes: squares in boxes and L shapes in boxes. Good overlay sensitivities are observed for both targets. The correlation to programmed shifts and image based overlay (IBO) is excellent. Despite the difference in shapes, the mDBO results are comparable for square and L shape targets. The impact of process variations on overlay measurements is studied using a focus and exposure matrix (FEM) wafer. Although the FEM wafer has larger process variations, the correlation of mDBO results with IBO measurements is as good as the normal process wafer. We demonstrate the feasibility of single pad DBO measurements with faster throughput and smaller target size, which is particularly important in high volume manufacturing environment.", "author_names": [ "Jie Li", "Oleg Anton Kritsun", "Yongdong Liu", "Prasad Dasari", "C Brooks Volkman", "Jiangtao Hu" ], "corpus_id": 121163021, "doc_id": "121163021", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Faster diffraction based overlay measurements with smaller targets using 3D gratings", "venue": "Advanced Lithography", "year": 2012 }, { "abstract": "We present effective medium approximation (EMA) that provides an homogeneous equivalent for the top layer of on chip interconnects in an integrated circuit. An empirical mixing model for straightforward and fast extraction of the effective dielectric constant of a slab of integrated circuit wiring and its analytical formulation based on Maxwell Garnett rule is presented for a range of aspect ratios, dielectric materials, metal fills, and frequencies. We expect this approach to find use in the electromagnetic modeling of System in Package. Experimental validation of proposed approach is demonstrated by free space measurement of a grating structure illuminated by a pair of lens horn antennas.", "author_names": [ "Sonia M Holik", "Timothy D Drysdale" ], "corpus_id": 14130226, "doc_id": "14130226", "n_citations": 4, "n_key_citations": 2, "score": 0, "title": "Simplified model for on chip interconnects in electromagnetic modelling of System in Package", "venue": "2010 International Conference on Electromagnetics in Advanced Applications", "year": 2010 }, { "abstract": "Abstract Ships often operate under challenging conditions, considering that marine environment can cause failures of the structure related to overloads, fatigue, corrosion and erosion. As a consequence, advanced methods and procedures are under development for the evaluation of the on site structural performance for both traditionally and newly designed ships. One of the main challenges in this field is the live monitoring of the loads acting on the ship hull; the load data processing can lead, through suited algorithms, to a real time control of ship trim and, as a consequence, to the development of automatic or semi automatic trim control systems. The presented procedure for load reconstruction requires a well suited sensing network. In this kind of application, a high resolution, large sampling frequencies and low sensibility to possible noise factors such as moisture, electromagnetic fields or vibrations are required. These requirements lead to the choice of Fiber Bragg Grating sensors. In this paper, an experimental methodology is proposed to reconstruct the characteristics of loads acting on a fast ship, starting from a finite number of local strain data obtained with FBG sensors. Sensors positions have been defined considering the ship hull as a beam subjected to a set of standard loads acting on a fast ship and taking into account the maximum strain positions. The development of the FE model of the ship hull, obtained from a three dimensional CAD of a real powerboat obtained with a 3D scan, allows the calculation of the strain field related to a set of standard loads applied on the ship. The above mentioned data are used as input for a fast computational algorithm, in which standard and actual strain fields provided by a network of FBG sensors are compared to reach the reconstruction of global loads acting on the structure. The algorithm has been effectively applied in sailing condition to the powerboat, detecting the acting loads on the hull in real time.", "author_names": [ "Pierluigi Fanelli", "Alessandro Mercuri", "Simone Trupiano", "Francesco Vivio", "Giacomo Falcucci", "Elio Jannelli" ], "corpus_id": 213675123, "doc_id": "213675123", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Live reconstruction of global loads on a powerboat using local strain FBG measurements", "venue": "", "year": 2019 }, { "abstract": "Rigorous simulations using combined finite/boundary element methods (FEM/BEM) are often too time consuming for the rapid evaluation of long surface acoustic wave (SAW) structures, and soon become impractical as device length increases. This situation is complicated by the need of subsequent design modifications and analyses. Scalar models, and in particular, transmission line (TL) based network descriptions, enable fast evaluation of arbitrary device topologies comprised of inter digital transducers (IDTs) and reflector/grating structures. For example, simulating a resonator structure using a network model reduces computation time from days or hours to minutes, allowing the identification of optimal designs, which may then be further analyzed using rigorous FEM/BEM techniques. The traditional network model (NM) consists of mismatched TLs, shunt susceptances, and transformers, and has been successfully used to simulate transduction and propagation of pure Rayleigh type and generalized SAWs in periodic structures. In these cases, it is often acceptable to neglect bulk acoustic wave (BAW) radiation, since the operational frequencies of the SAW devices are far away from the BAW radiation frequency. However, in the case of pure shear horizontal (SH) SAW orientations significant BAW scattering is frequently observed because the BAW radiation frequency takes place near the SAW bandwidth, and thus the traditional NM fails to account for the energy radiated to the bulk. In this work a modification of the traditional NM is introduced that accounts for energy loss near the upper stopband edge for a long periodic structure, thus allowing the use of the NM to adequately simulate structures along pure SH SAW orientations. The BAW radiation is modeled by a frequency dependent shunt conductance located at electrode edge discontinuities. A parameter extraction technique is presented that allows the rapid determination of frequency dependent parameters. In particular, the parameters are fit to FEM/BEM computed dispersion and harmonic admittance relations. The response of a SH SAW resonator was computed using the NM and compared to measurements of devices fabricated on langasite, Euler Angles (0deg, 22deg, 90deg) Good agreement is observed with a slight variation in center frequency ~0.25% thus verifying the modified model and its applicability to rapid design of pure shear horizontal SAW devices", "author_names": [ "T B Pollard", "Mauricio Pereira da Cunha" ], "corpus_id": 25444868, "doc_id": "25444868", "n_citations": 2, "n_key_citations": 1, "score": 0, "title": "6A 3 Pure Shear Horizontal SAW Network Model for Periodic Structures Including Bulk Scattering", "venue": "2006 IEEE Ultrasonics Symposium", "year": 2006 }, { "abstract": "A quantum random number generator (QRNG) generates genuine randomness from the intrinsic probabilistic nature of quantum mechanics. The central problems for most QRNGs are estimating the entropy of the genuine randomness and producing such randomness at high rates. Here we propose and demonstrate a fast semi self testing QRNG at a rate of 24 Mbit/s based on a high dimensional entanglement system, in which the user monitors the entropy in real time via the observation of a nonlocal quantum interference. Our work provides a practical approach to a robust QRNG with trusted but error prone devices. Introduction. Randomness is indispensable for information processing. Quantum random number generators (QRNGs) can generate true randomness by exploiting the fundamental indeterminism of quantum mechanics [1] Most current QRNGs are photonic systems built with trusted and calibrated devices [2] and provide Gbit/s generation speeds at relatively low cost. However, a central issue in these QRNGs is how to certify and quantify the entropy of the genuine randomness, i.e. the randomness that originates from the intrinsic unpredictability of measurements in quantum mechanics. Entropy estimates for specific setups were recently proposed using sophisticated theoretical models [3] Nevertheless, these techniques require parameter characterization which may be difficult to accurately assess in practice. An elegant solution to estimating the entropy is the device independent (DI) or self testing QRNG [1, 4, 5] but its practical implementation is challenging because it requires loophole free violation of Bell's inequality, resulting in low generation rates of ~1 bit/s [1, 5] Recently, Lunghi et al. proposed a more practical solution without the need for Bell violation [6] which can be termed semi self testing, in which the randomness can be guaranteed based on a few general assumptions that do not require detailed device characterization. This scheme is highly desirable as it focuses on real world implementations with trusted but error prone devices, although its implementation to date still suffers from low generation rates of tens of bits/s [6] In this work, based on high dimensional entanglement, we propose and experimentally demonstrate a simple, practical and fast semi self testing QRNG at a rate over 24 Mbits/s. The amount of genuine quantum randomness is quantified directly from observation of a nonlocal interference and a pair of incompatible quantum measurements, and it is separated from other sources of randomness such as technical noise with a randomness extractor. We achieved the high generation rate by virtue of a number of experimental features: a high dimensional time energy entangled photon source capable of producing multiple random bits per photon, a high visibility Franson interferometer for evaluating entanglement, and high efficiency superconducting nanowire single photon detectors (SNSPDs) Protocol. An entanglement source is used to generate high dimensional entangled photon pairs. In the ideal case, the Nd dimensional entangled state can be written as |ps> 1 Nd Nd 1 i=0 |i> A |i> B. (1) This state is observed by two measurement systems A and B. The randomness is generated from A, while B is used to test the states. To model imperfections, we assume that the state rA of system A is not pure and is correlated with environmental noise. Using the same concept as the semi self testing QRNG [6] we assume the devices in the protocol are not deliberately designed to fool the user, but the implementation may be imperfect. The central task is to estimate the amount of genuine randomness based only on measurements. This is a nontrivial task as the observed randomness can have different origins. If the state rA is a superposition of high dimensional states, then the outcome Ri cannot be predicted with certainty, even if the internal state is known, thus resulting in genuine quantum randomness. On the other hand, the randomness may be due to technical imperfections such as detector noise and temperature fluctuations, whose randomness clearly contains no quantum randomness, since the outcome Ri can be perfectly guessed if the imperfections were well quantified. In our approach, the amount of genuine randomness is quantified via the uncertainty relation [7, 8] from a pair of incompatible quantum measurements, namely time measurement T and frequency measurement W. T is realized by directly measuring the photon's arrival time, while W is performed by Franson interferometry [9] In particular, the Franson visibility V is used to bound the randomness. Classical fields result in V that is no greater than 50% For a maximally entangled state, V would be unity in the ideal case [9, 10] Conceptually, V 50% guarantees that the source's output is entangled and thus contains genuine randomness. More rigorously, Ref. [11] has proved that V provides an explicit bound for the correlations in W, under the assumption that the quantum state is Gaussian, which in turns bounds the conditional maximum entropy (given system B) in W via the theory developed in [8] By using the entropic uncertainty relation for smooth entropies [7] we can determine the conditional min entropy given the environmental noise and thus the guessing probability, i.e. the amount of genuine randomness. Our protocol provides self monitoring because measurements of V directly quantify the amount of genuine randomness in the observed data. A threshold value V0 is pre selected and the randomness can be generated only when the observation satisfies V V0. Two particular advantages of this approach are: (i) the observation of V does not rely on detailed models of the devices that are employed; and (ii) no loophole free Bell inequality violation is required. Experiment. Figure 1 shows our experimental setup. It uses a high dimensional time energy entanglement source based on spontaneous parametric down conversion (SPDC) in a PPKTP waveguide [12] which supports multiple spatial modes at telecom wavelengths. The 46.1 mm grating period was designed for type II quasi phase matched wavelength degenerate outputs at 1560 nm in the fundamental modes of the signal C HWP PBS Diode Laser", "author_names": [ "Feihu Xu", "Jeffrey H Shapiro", "Franco N C Wong" ], "corpus_id": 51849701, "doc_id": "51849701", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Experimental fast quantum random number generation using high dimensional entanglement with semi self testing", "venue": "", "year": 2016 } ]

[ { "abstract": "It is widely accepted within the community that to achieve a sustainable society with an energy mix primarily based on solar energy we need an efficient strategy to convert and store sunlight into chemical fuels. A photoelectrochemical (PEC) device would therefore play a key role in offering the possibility of carbon neutral solar fuel production through artificial photosynthesis. The past five years have seen a surge in the development of promising semiconductor materials. In addition, low cost earth abundant co catalysts are ubiquitous in their employment in water splitting cells due to the sluggish kinetics of the oxygen evolution reaction (OER) This review commences with a fundamental understanding of semiconductor properties and charge transfer processes in a PEC device. We then describe various configurations of PEC devices, including single light absorber cells and multi light absorber devices (PEC, PV PEC and PV/electrolyser tandem cell) Recent progress on both photoelectrode materials (light absorbers) and electrocatalysts is summarized, and important factors which dominate photoelectrode performance, including light absorption, charge separation and transport, surface chemical reaction rate and the stability of the photoanode, are discussed. Controlling semiconductor properties is the primary concern in developing materials for solar water splitting. Accordingly, strategies to address the challenges for materials development in this area, such as the adoption of smart architectures, innovative device configuration design, co catalyst loading, and surface protection layer deposition, are outlined throughout the text, to deliver a highly efficient and stable PEC device for water splitting.", "author_names": [ "Chaoran Jiang", "Savio J A Moniz", "Aiqin Wang", "Tao Zhang", "Junwang Tang" ], "corpus_id": 3725023, "doc_id": "3725023", "n_citations": 532, "n_key_citations": 1, "score": 1, "title": "Photoelectrochemical devices for solar water splitting materials and challenges.", "venue": "Chemical Society reviews", "year": 2017 }, { "abstract": "Photoelectrochemical water splitting (PEC) offers a promising path for sustainable generation of hydrogen fuel. However, improving solar fuel water splitting efficiency facing tremendous challenges, due to the energy loss related to fast recombination of the photogenerated charge carriers, electrode degradation, as well as limited light harvesting. This review focuses on the brief introduction of basic fundamental of PEC water splitting and the concept of various types of water splitting approaches. Numerous engineering strategies for the investgating of the higher efficiency of the PEC, including charge separation, light harvesting, and co catalysts doping, have been discussed. Moreover, recent remarkable progress and developments for PEC water splitting with some promising materials are discussed. Recent advanced applications of PEC are also reviewed. Finally, the review concludes with a summary and future outlook of this hot field.", "author_names": [ "Bandar Y Alfaifi", "Habib Ullah", "Sulaiman Yahya Alfaifi", "Asif Ali Tahir", "Tapas K Mallick" ], "corpus_id": 53627481, "doc_id": "53627481", "n_citations": 30, "n_key_citations": 0, "score": 0, "title": "Photoelectrochemical solar water splitting: From basic principles to advanced devices", "venue": "", "year": 2018 }, { "abstract": "Photoelectrochemical (PEC) water splitting is a promising route for solar energy conversion to hydrogen. It produces clean hydrogen that can be used for refueling fuel cell electric vehicles or serve as a feedstock for the production of drop in liquid fuels by CO2 hydrogenation or ammonia via the Haber Bosch process. The greatest challenges towards PEC solar water splitting technology lay in the selection and optimization of stable photocatalytic materials for water photo oxidation, and the design of scalable PEC devices that produce hydrogen at a competitive cost. Iron oxide (a Fe2O3, hematite) is one of few materials meeting the basic selection criteria for stable photoanodes, but its poor charge transport properties and fast recombination present challenges for efficient charge separation and collection. We explore innovative solutions to these challenges using ultrathin (20 30 nm) films on specular back reflectors. This optical design traps the light in otherwise nearly translucent ultrathin films, amplifying the intensity close to the surface wherein photogenerated charge carriers can reach the surface and split water before recombination takes place.1 This is the enabling key towards the development of high efficiency epilayers whose properties can be tailored by material design at the atomic scale.2 Our recent efforts to uncover the design rules of these photoanodes will be presented. On the other end of the spectrum we explore innovative device architectures and operation schemes for scalable and competitive PEC solar water splitting technology. These include power and optical management schemes for optimizing the hydrogen and power outputs of PEC PV tandem cells,3 and separating the hydrogen production from the oxygen production for safe operation and on site hydrogen production.4", "author_names": [ "Avner Rothschild" ], "corpus_id": 105826236, "doc_id": "105826236", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Photoelectrochemical water splitting for solar energy conversion and storage", "venue": "", "year": 2017 }, { "abstract": "In order to be economically competitive with simple \"brute force\" (i.e. PV electrolyzer) strategies or the production of promising solar fuels, like H2, from fossil fuels, a practical photoelectrochemical device must optimize cost, longevity, and performance. A promising approach that meets these requirements is the combination of stable and inexpensive oxide semiconductor electrodes in a tandem photoelectrochemical device. In this article, we give an overview of the field including an examination of the potential solar to fuel conversion efficiency expected in a device with realistic losses. We next discuss recent advances with increasing the performance of promising semiconductor electrode materials and highlight how these advances have led to state of the art solar to chemical efficiencies in the 2 3% range in real devices. Challenges for further optimization are further outlined.", "author_names": [ "Mathieu S Prevot", "Kevin Sivula" ], "corpus_id": 94059741, "doc_id": "94059741", "n_citations": 366, "n_key_citations": 2, "score": 0, "title": "Photoelectrochemical Tandem Cells for Solar Water Splitting", "venue": "", "year": 2013 }, { "abstract": "The magnitude of energy challenge not only calls for efficient devices but also for abundant, inexpensive, and stable photoactive materials that can enable efficient light harvesting, charge separation and collection, as well as chemical transformations. Photoelectrochemical systems based on semiconductor materials have the possibility to transform solar energy directly into chemical energy the so called \"solar hydrogen.\" The current challenge lies in the harvesting of a larger fraction of electromagnetic spectrum by enhancing the absorbance of electrode materials. In this context, atomically precise thin films of metal oxide semiconductors and their multilayered junctions are promising candidates to integrate high surface areas with well defined electrode substrate interface. Given its self limited growth mechanism, the atomic layer deposition (ALD) technique offers a wide range of capabilities to deposit and modify materials at the nanoscale. In addition, it opens new frontiers for developing precursor chemistry that is inevitable to design new processes. Herein, the authors review the properties and potential of metal oxide thin films deposited by ALD for their application in photoelectrochemical water splitting application. The first part of the review covers the basics of ALD processes followed by a brief discussion on the electrochemistry of water splitting reaction. The second part focuses on different MOx films deposited by atomic layer deposition for water splitting applications; in this section, The authors discuss the most explored MOx semiconductors, namely, Fe2O3, TiO2, WO3, and ZnO, as active materials and refer to their application as protective coatings, conductive scaffolds, or in heterojunctions. The third part deals with the current challenges and future prospects of ALD processed MOx thin films for water splitting reactions.", "author_names": [ "Trilok Singh", "Thomas Lehnen", "Tessa Leuning", "Sanjay Mathur" ], "corpus_id": 96065866, "doc_id": "96065866", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Atomic layer deposition grown MOx thin films for solar water splitting: Prospects and challenges", "venue": "", "year": 2015 }, { "abstract": "The generation and storage of renewable energy is one of the key challenges for the transition to a sustainable society. Hydrogen (H2) the most abundant element on earth, is believed to be an important energy carrier in the near future. It can be either used directly as a fuel, or further converted with CO2 to form hydrocarbons through well known catalytic processes. Water is the most sustainable resource for production of hydrogen. A highly promising approach to generate hydrogen from water is photoelectrochemistry. Such a device aims to integrate photovoltaics (solar panels) and electrolysis, potentially being an efficient energy conversion system. The research described in this thesis focuses on the development of photoelectrochemical devices for hydrogen generation from water. In particular, electrochemistry was utilized to coat flat and microwire structured silicon, one of the main materials in photovoltaic cells, with metals or semiconductors. These layers are necessary, among others, to facilitate oxygen or hydrogen evolution, improve the use of the solar spectrum, and increase photovoltage of devices. Silicon microwire structuring enhances light absorption and increases the active surface area for reaction. The findings of this work provide: i) a way to control the size and density of platinum particles on Si surfaces, ii) a method to deposit materials spatioselectively on top and bottom segments of microwires with axial p/n junctions, iii) a theory for deactivation of tungsten oxide in water oxidation, and iv) evaluation of the functionality of bismuth vanadate, when deposited onto silicon microwires.", "author_names": [ "Alexander Milbrat" ], "corpus_id": 103596629, "doc_id": "103596629", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Electrochemical coating of micro structured silicon for photoelectrochemical water splitting", "venue": "", "year": 2018 }, { "abstract": "Water photolysis is a sustainable technology to convert natural solar energy and water into chemical fuels and is thus considered a thorough solution to the forthcoming energy crises. Unassisted water splitting that could directly harvest solar light and subsequently split water in a single device has become an important research theme. Three types of tandem devices including photoelectrochemical (PEC) photovoltaic (PV) cell/PEC and PV/electrolyser tandem cells are proposed to realize water photolysis at different levels of integration and component. Recent progress in tandem water splitting devices is summarized, and crucial issues on device optimization from the perspective of each photo absorber functionalities in band edge potential, light absorptivity and transmittance are discussed. By increasing the performances of stand alone PEC or PV devices, a 20% solar to hydrogen efficiency is predicted that is a significant value towards further application in practice. Accordingly, the challenges for materials development and configuration optimization are further outlined.", "author_names": [ "Kan Zhang", "Ming Ma", "Ping Li", "Dong Hwan Wang", "Jong Hyeok Park" ], "corpus_id": 100090706, "doc_id": "100090706", "n_citations": 181, "n_key_citations": 0, "score": 0, "title": "Water Splitting Progress in Tandem Devices: Moving Photolysis beyond Electrolysis", "venue": "", "year": 2016 }, { "abstract": "The work detailed in this thesis is organized in the following manner: In Chapter 1 we discuss electrochemical and photoelectrochemical catalysts in the context of their application for solar to hydrogen devices. During this introduction we will give an overview of the current state of the field, discussing the different kinds of materials that are being investigated before giving a brief description of some actual solar to hydrogen devices and finishing with a discussion of the current and future challenges in the field. Chapter 2 is a description of the different techniques used throughout this thesis. Once having set the bases, we shall start with the actual research, which corresponds to Chapters 3 to 5. Chapter 3 and 4 deal with the effect of trace metal impurities in electrochemical water splitting. In Chapter 3 we show that adventitious nickel at trace levels can act as a water oxidation catalyst in mildly basic aqueous solutions at overpotentials comparable to many recently reported water oxidation catalysts, therefore serving to raise the burden of proof required of new materials in this field. Chapter 4 shows how silver ions leaking from Ag/AgCl reference electrodes in aqueous buffers at low pH can deposit on the working electrode as Ag(0) and catalyze the hydrogen evolution reaction, calling into question the validity of any reports using these electrodes that cannot demonstrate significantly superior activity to the baseline we set in this chapter. In Chapter 5 we describe a direct hydrothermal deposition method to prepare Cobalt doped MoS2 thin films onto transparent Fluorine doped SnO2 substrate and demonstrate that the obtained films display good activity for the hydrogen evolution reaction from acid solution.", "author_names": [ "I Barba" ], "corpus_id": 102979995, "doc_id": "102979995", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Investigations into electrochemical water splitting", "venue": "", "year": 2017 }, { "abstract": "The key to successful deployment of photoelectrochemical (PEC) water splitting for commercial renewable hydrogen production will be in the identification and development of innovative semiconductor materials systems and devices, likely involving multijunction configurations. Multijunction approaches offer some of the best hope for achieving practical PEC hydrogen production in the near term, but complex materials and interface issues still need to be addressed by the scientific community. This chapter explores the challenges and benefits of large scale solar water splitting for renewable hydrogen production, with specific focus on the multijunction PEC production pathways. The technical motivation and approach in the R&D of multijunction PEC devices and systems are considered, and examples of progress in laboratory scale prototypes are presented.", "author_names": [ "Eric L Miller", "Alexander Deangelis", "Stewart A Mallory" ], "corpus_id": 134076973, "doc_id": "134076973", "n_citations": 7, "n_key_citations": 2, "score": 0, "title": "Multijunction Approaches to Photoelectrochemical Water Splitting", "venue": "", "year": 2012 }, { "abstract": "One of the key challenges in photoelectrochemical water splitting is to identify efficient semiconductors with band gaps of the order of ~2 eV to operate as the large band gap component in water splitting tandem devices. Here, we address this challenge by extensive computational screening of ternary sulfides followed by synthesis and confirmation of the properties of one of the most promising materials. The screening focusses on materials with ABS3 composition taking both perovskite and non perovskite structures into consideration, and the material selection is based on descriptors for thermodynamic stability, light absorption, charge mobility, and defect tolerance. One of the most promising candidates identified is LaYS3. This material was synthesized directly in thin film form demonstrating its stability, crystal structure, light absorption, and strong photoluminescence. These data confirms its potential applicability in tandem photoelectrochemical devices for hydrogen production.", "author_names": [ "Korina Kuhar", "Andrea Crovetto", "Mohnish Pandey", "Kristian Sommer Thygesen", "Brian Seger", "Peter C K Vesborg", "Ole Hansen", "Ib Chorkendorff", "Karsten Wedel Jacobsen" ], "corpus_id": 103501809, "doc_id": "103501809", "n_citations": 54, "n_key_citations": 0, "score": 0, "title": "Sulfide perovskites for solar energy conversion applications: computational screening and synthesis of the selected compound LaYS3", "venue": "", "year": 2017 } ]

[ { "abstract": "Critical dimension measurements for state of the art sub micron semiconductor processes are typically accomplished using automated scanning electron microscopes. The measurements generated in these instruments are primarily based upon secondary electron imaging techniques. Several issues associated with this mode of SEM imaging that directly impact the precision and accuracy of the measurement system are reviewed. These issues have led to the current investigation of SEM metrology utilizing backscattered electron imaging techniques. The implications and differences between SE and BSE imaging techniques and their relation to CD measurements are discussed in this work.(c) (1994) COPYRIGHT SPIE The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.", "author_names": [ "Neal T Sullivan", "Robert Newcomb" ], "corpus_id": 119499668, "doc_id": "119499668", "n_citations": 5, "n_key_citations": 0, "score": 1, "title": "Critical dimension measurement in the SEM: comparison of backscattered vs. secondary electron detection", "venue": "", "year": 1994 }, { "abstract": "Abstract In a scanning electron microscope (SEM) an electron beam sets up an omni directional source of scattered electrons within a specimen. Diffraction of these electrons will occur simultaneously on all lattice planes in the sample and the backscattered electrons (BSE) which escape from the specimen, will form a diffraction pattern that can be imaged on a phosphor screen. This is the basis of electron backscatter diffraction (EBSD) Similar diffraction effects cause individual grains of different orientations to give different total BSE. SEM images that exploit this effect will show orientation contrast (OC) EBSD and OC imaging are SEM based crystallographic tools. EBSD enables measurement of the crystallographic orientation of individual rock forming minerals as small as 1 mm, and the calculation of misorientation axes and angles between any two data points. OC images enable mapping of all misorientation boundaries in a specimen and thus provide a location map for EBSD analyses. EBSD coupled to OC imaging in the SEM enables complete specimen microtextures and mesotextures to be determined. EBSD and OC imaging can be applied to any mineral at a range of scales and enable us to expand the microstructural approach, so successful in studies of quartz rocks, for example, to the full range of rock forming minerals. Automated EBSD analysis of rocks remains problematic, although continuing technical developments are enabling progress in this area. EBSD and OC are important new tools for petrologists and petrographers. Present and future applications of EBSD and OC imaging include phase identification, studying deformation mechanisms, constraining dislocation slip systems, empirical quantification of microstructures, studying metamorphic processes, studying magmatic processes, and constraining geochemical microsampling. In all these cases, quantitative crystallographic orientation data enable more rigorous testing of models to explain observed microstructures.", "author_names": [ "David J Prior", "Alan P Boyle", "Frank E Brenker", "Michael C Cheadle", "Austin Day", "Gloria Lopez", "Luca Peruzzo", "Graham J Potts", "Steve Reddy", "Richard Spiess", "Nicholas E Timms", "Patrick Trimby", "John Wheeler", "Lena Zetterstrom" ], "corpus_id": 39471231, "doc_id": "39471231", "n_citations": 626, "n_key_citations": 32, "score": 1, "title": "The application of electron backscatter diffraction and orientation contrast imaging in the SEM to textural problems in rocks", "venue": "", "year": 1999 }, { "abstract": "The so called \"total yield\" approach often fails to explain the measured sign of the surface potential, VS, and the shift of the nominal critical energy EC2 (where ddeg+edeg=1) of electron irradiated insulators. Here, a simple modification of this approach consists in including some extra interactions of the secondary and backscattered electrons with the electron traps generated previously by the irradiation itself. The trends in the evolution of the total yield, d+e, and of VS as a function of the irradiation time (from their initial values up to their steady values) are then deduced for a wide primary beam energy range (1 50 keV) and for different external collector (or specimen holder) bias. New mechanisms are suggested for the contrasts observed in insulators investigated in scanning electron microscopy (SEM) The present analysis applies for a wide variety of electron beam techniques (SEM, Auger electron spectroscopy, and electron probe microanalysis) operated on a wide variety of insulating specimens a.", "author_names": [ "Jacques Cazaux" ], "corpus_id": 117116596, "doc_id": "117116596", "n_citations": 194, "n_key_citations": 6, "score": 0, "title": "Some considerations on the secondary electron emission, d, from e irradiated insulators", "venue": "", "year": 1999 }, { "abstract": "Creep cavitation in an ex service nuclear steam header Type 316 stainless steel sample is investigated through a multiscale tomography workflow spanning eight orders of magnitude, combining X ray computed tomography (CT) plasma focused ion beam (FIB) scanning electron microscope (SEM) imaging and scanning transmission electron microscope (STEM) tomography. Guided by microscale X ray CT, nanoscale X ray CT is used to investigate the size and morphology of cavities at a triple point of grain boundaries. In order to understand the factors affecting the extent of cavitation, the orientation and crystallographic misorientation of each boundary is characterised using electron backscatter diffraction (EBSD) Additionally, in order to better understand boundary phase growth, the chemistry of a single boundary and its associated secondary phase precipitates is probed through STEM energy dispersive X ray (EDX) tomography. The difference in cavitation of the three grain boundaries investigated suggests that the orientation of grain boundaries with respect to the direction of principal stress is important in the promotion of cavity formation.", "author_names": [ "Thomas J A Slater", "Robert S Bradley", "Giacomo Bertali", "Remco Geurts", "S M Northover", "Michael G Burke", "Sarah J Haigh", "Timothy L Burnett", "Philip J Withers" ], "corpus_id": 21028, "doc_id": "21028", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "Multiscale correlative tomography: an investigation of creep cavitation in 316 stainless steel", "venue": "Scientific Reports", "year": 2017 }, { "abstract": "For studying the electrical properties (charge trapping, transport and secondary electron emission) of the polypropylene based nanocomposites with different contents of natural clay, the specimens were submitted to electron irradiation of a scanning electron microscope. A device, suitably mounted on the sample holder of the scanning electron microscope, was used to measure two currents (i.e. leakage and displacement currents) induced in the polypropylene based nanocomposites (polymer nanocomposites) under electron irradiation. The evolution of trapped charge during irradiation for each type of studied polymer nanocomposites is deduced. The amount of trapped charge at the steady state is also determined by measuring the change of secondary electron image size associated to the electron trajectory simulation. It is found, surprisingly, that not only the leakage current increases as a function of clay loading level but also trapped charge. However, this could be related to the increase of conductivity in one hand and to proliferation of interfaces between nanoparticles and neighbouring materials on the other hand. These two processes play crucial role in controlling the carrier transport (through polymer nanocomposites or/and along its surface) closely related to the charge storage and leakage current.", "author_names": [ "Latifa Ben Ammar", "Slim Fakhfakh", "Omar Jbara", "Sebastien Rondot" ], "corpus_id": 41096073, "doc_id": "41096073", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Effect of nanoclay concentration level on the electrical properties of polypropylene under electron irradiation in a SEM", "venue": "Journal of microscopy", "year": 2017 }, { "abstract": "This paper presents a characterization study of specimens manufactured from Ti 6Al 4V powder with the use of laser engineered net shaping technology (LENS) Two different orientations of the specimens were considered to analyze the loading direction influence on the material mechanical properties. Moreover, two sets of specimens, as built (without heat treatment) and after heat treatment, were used. An optical measurement system was also adopted for determining deformation of the specimen, areas of minimum and the maximum principal strain, and an effective plastic strain value at failure. The loading direction dependence on the material properties was observed with a significant influence of the orientation on the stress and strain level. Microstructure characterization was examined with the use of optical and scanning electron microscopes (SEM) in addition, the electron backscatter diffraction (EBSD) was also used. The fracture mechanism was discussed based on the fractography analysis. The presented comprehensive methodology proved to be effective and it could be implemented for different materials in additive technologies. The material data was used to obtain parameters for the selected constitutive model to simulate the energy absorbing structures manufactured with LENS technology. Therefore, a brief discussion related to numerical modelling of the LENS Ti 6Al 4V alloy was also included in the paper. The numerical modelling confirmed the correctness of the acquired material data resulting in a reasonable reproduction of the material behavior during the cellular structure deformation process.", "author_names": [ "Aleksandra Szafranska", "Anna Antolak-Dudka", "Pawel Baranowski", "Pawel Bogusz", "Dariusz Zasada", "Jerzy Malachowski", "Tomasz Czujko" ], "corpus_id": 83460355, "doc_id": "83460355", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Identification of Mechanical Properties for Titanium Alloy Ti 6Al 4V Produced Using LENS Technology", "venue": "Materials", "year": 2019 }, { "abstract": "Austenitisation is one of the most important factors in heat treatment process of dual phase high carbon steel, as it can affect the grain size, production of secondary phase precipitation, size of martensite laths and distribution of the phases. Despite the importance of this heat treatment on mechanical behaviour, its correlation on corrosion behaviour and electrochemical properties of high carbon steel required in depth investigation. The aim of this study is to investigate the effect of different austenitising temperatures on microstructure and corrosion behaviour of dual phase high carbon steel. Microstructural evolution was observed in situ using ultra high temperature laser microscope, and the steels have been characterised further using optical microscope, electron backscatter diffraction, 3D laser scanning confocal microscope, scanning electron microscope and energy energy dispersive spectroscope and electron probe microanalysis. The powerful electrochemical corrosion test was employed by using Tafel polarisation method to measure its corrosion rate. Results have indicated that higher austenitising temperature increased grain size of retained austenite and martensite, which reduced the grain boundary length, but at the same time increased the size and amount of carbide precipitations. As the main corrosion mechanisms in dual phase high carbon steel were pitting corrosion and intergranular corrosion, effect of generated precipitations has overcome grain boundary corrosion caused by influence of size and shape of microstructures and, thus, reduced the corrosion resistance around 9.68% as temperature increased. These findings are crucial for designing new applications from high carbon steels for mining and automotive industries.", "author_names": [ "Wilson Handoko", "Farshid Pahlevani", "Veena Sahajwalla" ], "corpus_id": 199474693, "doc_id": "199474693", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Effect of austenitisation temperature on corrosion resistance properties of dual phase high carbon steel", "venue": "Journal of Materials Science", "year": 2019 }, { "abstract": "Focused ion beam (FIB) milling has enabled the development of key microstructure characterization techniques (e.g. 3D electron backscatter diffraction (EBSD) 3D scanning electron microscopy imaging, site specific sample preparation for transmission electron microscopy, site specific atom probe tomography) and micro mechanical testing techniques (e.g. micro pillar compression, micro beam bending, in situ TEM nanoindentation) Yet, in most milling conditions, some degree of FIB damage is introduced via material redeposition, Ga+ ion implantation or another mechanism. The level of damage and its influence vary strongly with milling conditions and materials characteristics, and cannot always be minimized. Here, a masking technique is introduced, that employs standard FIB SEM equipment to protect specific surfaces from redeposition and ion implantation. To investigate the efficiency of this technique, high angular resolution EBSD (HR EBSD) has been used to monitor the quality of the top surface of several micro pillars, as they were created by milling a ringcore hole in a stress free silicon wafer, with or without protection due to an \"umbrella\" HR EBSD provides a high sensitivity estimation of the amount of FIB damage on the surface. Without the umbrella, EBSD patterns are severely influenced, especially within 5 um of the milled region. With an optimized umbrella, sharp diffraction patterns are obtained near the hole, as revealed by average cross correlation factors greater than 0.9 and equivalent phantom strains of the order 2 x 10 4. Thus, the umbrella method is an efficient and versatile tool to support a variety of FIB based techniques.", "author_names": [ "Tijmen Vermeij", "Emeric Plancher", "Cemal Cem Tasan" ], "corpus_id": 3494135, "doc_id": "3494135", "n_citations": 20, "n_key_citations": 0, "score": 0, "title": "Preventing damage and redeposition during focused ion beam milling: The \"umbrella\" method.", "venue": "Ultramicroscopy", "year": 2018 }, { "abstract": "The interaction of ionizing radiation with matter is of critical importance in numerous areas of science and technology like space and vacuum technology and even medicine and biotechnology. Secondary electron emission is a consequence of electron irradiation on materials. We achieve extremely low secondary electron emission yield values smaller than 0.2, even up to incident electron energies ~1 keV, due to an undocumented synergy between neighbouring metal and dielectric domains in composite samples. To investigate this experimental discovery, we propose a simple 3D model where the dielectric and metallic domains are arranged in parallel and interleaved. The proposed surface profile has a triangular shape to model the surface roughness. We obtain a continuous equation to describe the electric field that arises between grounded conductors and charged dielectrics domains. The calculated trajectories of secondary electrons in this 3D geometry are used to predict dynamic secondary emission yield, which strongly depends on the charge accumulated in the dielectric domains. This research paves the way to design new materials of low secondary emission yield, addressing the technological problem not yet resolved to inhibit the electron avalanche in RF equipment that limit their maximum working power.", "author_names": [ "Leandro Olano", "Maria E Davila", "J R Dennison", "Petronilo Martin-Iglesias", "Isabel Montero" ], "corpus_id": 203437238, "doc_id": "203437238", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Dynamic secondary electron emission in rough composite materials", "venue": "Scientific Reports", "year": 2019 }, { "abstract": "This paper presents a high signal to noise ratio electron energy spectrometer attachment for the scanning electron microscope (SEM) designed to measure changes in specimen surface potential from secondary electrons and extract specimen atomic number information from backscattered electrons. Experimental results are presented, which demonstrate that the spectrometer can in principle detect specimen voltage changes well into the sub mV range, and distinguish close atomic numbers by a signal to noise ratio of better than 20. The spectrometer has applications for quantitatively mapping specimen surface voltage and atomic number variations on the nano scale.", "author_names": [ "Hung Quang Hoang", "Mans Osterberg", "Anjam Khursheed" ], "corpus_id": 205522467, "doc_id": "205522467", "n_citations": 16, "n_key_citations": 2, "score": 0, "title": "A high signal to noise ratio toroidal electron spectrometer for the SEM.", "venue": "Ultramicroscopy", "year": 2011 } ]

[ { "abstract": "We show that patterned defects can be used to disrupt the sublattice symmetry of graphene so as to open up a band gap. This way of modifying graphene's electronic structure does not rely on external agencies, the addition of new elements or special boundaries. The method is used to predict a planar, low energy, graphene allotrope with a band gap of 1.2 eV. This defect engineering also allows semiconducting ribbons of carbon to be fabricated within graphene. Linear arrangements of defects lead to naturally embedded ribbons of the semiconducting material in graphene, offering the prospect of two dimensional circuit logic composed entirely of carbon.", "author_names": [ "David J Appelhans", "Zhibin Lin", "Mark T Lusk" ], "corpus_id": 121233214, "doc_id": "121233214", "n_citations": 31, "n_key_citations": 0, "score": 1, "title": "Two dimensional carbon semiconductor: Density functional theory calculations", "venue": "", "year": 2010 }, { "abstract": "Abstract A recently proposed two dimensional (2D) carbon allotrope, tetrahex carbon, draws scientific attention due to its remarkable electronic and mechanical properties. This 2D carbon structure consists of tetragonal and hexagonal rings, and exhibits excellent semiconductor properties including a finite direct band gap and high carrier mobility, suggesting potential applications in semiconductor devices. In this paper, the electronic properties of fluorine/hydrogen adsorbed tetrahex C was investigated via first principles density functional theory calculations. It demonstrates that its band structure can be significantly tuned and could be metallic with dangling bonds from F/H adsorption. With increasing F/H adsorption density, it shows semiconducting behavior and the band gap is widening, mainly due to the sp2 bonded carbon being gradually converted to sp3 hybridization. It was also found that effective masses of charge carriers along the zigzag direction can largely reduce through adsorption of F/H, leading to potentially enhanced carrier mobility. Tetrahex C shows prominent anisotropicity and the tunability of effective masses through F/H adsorption is remarkably dependent on the crystal orientation. In addition, it was found that, the work function of the F adsorbed tetrahex C increases while electron affinity decreases, compared to the pristine one. However, the H covered carbon film shows significant reductions of both work function and electron affinity.", "author_names": [ "Yingguo Yang", "Guang Yang", "Xihong Peng" ], "corpus_id": 224901358, "doc_id": "224901358", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Electronic properties of fluorine/hydrogen adsorbed two dimensional tetrahex carbon: A first principles study", "venue": "", "year": 2020 }, { "abstract": "A new two dimensional boron carbon nitrogen (BCN) structure is predicted and is theoretically investigated based on density functional theory. The BCN structure belongs to the space group C222, and is composed of twelve B, twelve C and twelve N atoms per orthorhombic cell (named oC B12C12N12) It consists of small hollow spheres with two hexagons per sphere. The dynamical, thermal and mechanical stabilities of oC B12C12N12 are respectively evaluated by phonon spectroscopy, ab initio molecular dynamics calculations and elastic constant measurements. The simulated in plane stiffness and Poisson ratio display anisotropic features. The band structure shows that oC B12C12N12 is a direct semiconductor with a gap of 2.72 eV (GW) oC B12C12N12 has an absorption range from the visible light spectrum to the ultraviolet. Therefore, due to its small direct band gap and optical absorption, oC B12C12N12 may be a good candidate for electronic and optical applications.", "author_names": [ "Yihua Lu", "Xi Zhu", "Maoyan Wang" ], "corpus_id": 214263688, "doc_id": "214263688", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Theoretical investigations of a new two dimensional semiconducting boron carbon nitrogen structure", "venue": "", "year": 2020 }, { "abstract": "Abstract Twin graphene is a novel two dimensional semiconducting carbon allotrope with an intrinsic direct bandgap. To explore the excellent properties and potential applications of twin graphene, we performed first principle density functional theory calculations on the structural, electronic, and magnetic properties of twin graphene with dual doping of Al and Y (Y B, N, O) atoms at different sites (ortho, meta, and para) The combined processes of the formation of all Al Y dual doped twin graphene (AlY TG) systems are exothermic and form stable dual doped structures, and the most stable structure is the AlB TG system. For the B, N, or O atoms at the same doped site, the stability decreases in the order of AlB TG, AlN TG, and AlO TG. Dual doping regulates the bandgap of twin graphene in the cases of AlB and AlN doping. A transition from a semiconducting material into a metal is observed when AlO doping is used, while a transition from a direct semiconductor into an indirect semiconductor is observed for AlB doping at the ortho site. Different magnetic moments of the AlY TG systems are observed for different Y atoms placed at different doping sites. The AlN TG system remains nonmagnetic, while the AlB TG system has a magnetic moment of 1.01 mB only in the meta site, and the AlO TG systems have magnetic moments of 0.50 mB and 0.56 mB in the ortho and meta sites, respectively. Moreover, different doping concentrations can effectively affect the electronic structures and magnetisms of the AlY TG systems. For doping concentrations of 5.6% and 11.1% at the meta site, the AlB TG systems exhibit metal characteristics with a high spin polarization. The results show that the electronic and magnetic properties of twin graphene can be modulated via Al Y (Y B, N, O) dual doping, indicating that twin graphene has potential applications in nanomagnets and spintronics devices.", "author_names": [ "Bing Yu", "You Xie", "Xiu Wu", "Yue Gao", "Su-fang Wang", "Jian-Min Zhang" ], "corpus_id": 234251179, "doc_id": "234251179", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Structural and electronic properties of AlY (Y B, N, O) dual doped twin graphene: A density functional theory study", "venue": "", "year": 2021 }, { "abstract": "Graphitic carbon nitride has been predicted to be structurally analogous to carbon only graphite, yet with an inherent bandgap. We have grown, for the first time, macroscopically large crystalline thin films of triazine based, graphitic carbon nitride (TGCN) using an ionothermal, interfacial reaction starting with the abundant monomer dicyandiamide. The films consist of stacked, two dimensional (2D) crystals between a few and several hundreds of atomic layers in thickness. Scanning force and transmission electron microscopy show long range, in plane order, while optical spectroscopy, X ray photoelectron spectroscopy, and density functional theory calculations corroborate a direct bandgap between 1.6 and 2.0 eV. Thus TGCN is of interest for electronic devices, such as field effect transistors and light emitting diodes.", "author_names": [ "Gerardo Algara-Siller", "Nikolai Severin", "Samantha Yu-Ling Chong", "Torbjorn Bjorkman", "Robert G Palgrave", "Andrea Laybourn", "Markus Antonietti", "Yaroslav Z Khimyak", "Arkady V Krasheninnikov", "Jurgen P Rabe", "Ute Kaiser", "Andrew I Cooper", "Arne Thomas", "Michael J Bojdys" ], "corpus_id": 18000173, "doc_id": "18000173", "n_citations": 379, "n_key_citations": 2, "score": 0, "title": "Triazine based graphitic carbon nitride: a two dimensional semiconductor.", "venue": "Angewandte Chemie", "year": 2014 }, { "abstract": "Two dimensional (2D) semiconductors, such as graphitic carbon nitride (g C3N4) molybdenum disulfide (MoS2) and phosphorene, with desirable optoelectronic properties and large photoreactive contact area for light absorption, have been widely used as donors and acceptors in high quality heterojunction solar cells. In this work, by using first principles density functional theory calculations, we demonstrate that tellurene is a promising candidate 2D semiconductor for designing highly efficient solar cells due to its desirable optoelectronic properties (an ideal band gap of 1.47 eV, a high carrier mobility up to 2.87 x 103 cm2 V 1 s 1, strong visible light absorption up to 5.0 x 105 cm 1 and high stability in ambient conditions) superior to existing 2D semiconductors used in solar cells. Furthermore, we find that tellurene and TMDs show desirable type II band alignment for constructing highly efficient heterojunction solar cells with strong charge separation and enhanced sunlight absorption. In particular, the calculated maximum power conversion efficiency (PCE) of our designed Te/WTe2 and Te/MoTe2 heterojunction solar cells can reach as high as 22.5% and 20.1% respectively.", "author_names": [ "Kai-Hsin Wu", "Huanhuan Ma", "Yunzhi Gao", "Wei Hu", "Jinlong Yang" ], "corpus_id": 104340828, "doc_id": "104340828", "n_citations": 38, "n_key_citations": 0, "score": 0, "title": "Highly efficient heterojunction solar cells based on two dimensional tellurene and transition metal dichalcogenides", "venue": "", "year": 2019 }, { "abstract": "Designing new two dimensional (2D) materials with novel band topologies has continuously attracted intense interest in fundamental science and potential applications. Here, we report a unique 2D Mg2C monolayer featuring quasi planar hexa coordinate magnesium and hexa coordinate carbon, which can be tuned from a metal to a semiconductor. The system has been studied using density functional theory, including electronic structure calculations and molecular dynamics simulations. In the freestanding state, the Mg2C monolayer behaves as a weak metal; however, by increasing the biaxial tensile strains, it can gradually be modulated to a gapless semimetal and then to a semiconductor. The Mg2C monolayer exhibits excellent dynamic and thermal stabilities and is also the global minimum of the 2D Mg2C system, implying the feasibility of its experimental synthesis. With unique band structures, the material may find applications in optoelectronics and electromechanics.", "author_names": [ "Lingbiao Meng", "Shuang Ni", "Minjie Zhou", "Yingjuan Zhang", "Zhaoguo Li", "Weidong Wu" ], "corpus_id": 46878299, "doc_id": "46878299", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Metal semiconductor transition of two dimensional Mg2C monolayer induced by biaxial tensile strain.", "venue": "Physical chemistry chemical physics PCCP", "year": 2017 }, { "abstract": "The existence of two novel hybrid two dimensional (2D) monolayers, 2D B3C2P3 and 2D B2C4P2, has been predicted based on the density functional theory calculations. It has been shown that these materials possess structural and thermodynamic stability. 2D B3C2P3 is a moderate band gap semiconductor, while 2D B2C4P2 is a zero band gap semiconductor. It has also been shown that 2D B3C2P3 has a highly tunable band gap under the effect of strain and substrate engineering. Moreover, 2D B3C2P3 produces low barriers for dissociation of water and hydrogen molecules on its surface, and shows fast recovery after desorption of the molecules. The novel materials can be fabricated by carbon doping of boron phosphide and directly by arc discharge and laser ablation and vaporization. Applications of 2D B3C2P3 in renewable energy and straintronic nanodevices have been proposed.", "author_names": [ "Andrey A Kistanov", "Stepan A Shcherbinin", "Svetlana V Ustiuzhanina", "Marko Huttula", "Wei Cao", "Vladimir R Nikitenko", "Oleg V Prezhdo" ], "corpus_id": 232481830, "doc_id": "232481830", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "First Principles Prediction of Two Dimensional B3C2P3 and B2C4P2: Structural Stability, Fundamental Properties, and Renewable Energy Applications.", "venue": "The journal of physical chemistry letters", "year": 2021 }, { "abstract": "A new carbon based two dimensional crystalline nanostructure was discovered. The nanostructure was facilely constructed by chemical vapor deposition of benzene on Cu(111) in an ultrahigh vacuum chamber. A low temperature scanning tunneling microscopy and spectroscopy study of the nanostructure indicated that it has an orthorhombic superstructure and a semiconductor character with an energy gap of 0.8 eV. An X ray photoelectron spectroscopy study showed that C C(sp(2) bonding is predominantly preserved, suggesting a framework consisting of p conjugated building blocks. The periodic nanostructure was found to be a surprisingly excellent template for isolating and stabilizing magnetic atoms: Co atoms deposited on it can be well dispersed and form locally ordered atomic chains with their atomic magnetism preserved. Therefore the nanostructure may be suitable for organic spintronic applications. The most likely structural model for the nanostructure is proposed with the aid of density functional theory calculations and simulations, suggesting that the 2D nanostructure may consist of polyphenylene chains interconnected by Cu adatoms.", "author_names": [ "Qi Han", "Huan Shan", "Jialiang Deng", "Aidi Zhao", "Bing Wang", "J G Hou" ], "corpus_id": 205915674, "doc_id": "205915674", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Construction of carbon based two dimensional crystalline nanostructure by chemical vapor deposition of benzene on Cu(111)", "venue": "Nanoscale", "year": 2014 }, { "abstract": "Abstract Graphitic carbon nitride (g C3N4, GCN) shows excellent photocatalytic activity for a myriad of reactions due to its unique traits and semiconducting properties. The design of a semiconductor heterojunction by hybridizing GCN and other materials with appropriate band structures has profiled one of the most fascinating approaches to enhance the photocatalytic efficiency of GCN. In our simulation, a metal free heterojunction was developed by incorporating zero dimensional (0D) black phosphorus quantum dots (BPQDs) with two dimensional (2D) GCN. The 0D/2D BPQD/GCN heterojunction was systematically investigated by using density functional theory (DFT) calculations. Various orientations of BPQD on GCN were compared. The electronic structure and charge density distribution of the BPQD/GCN composite were calculated to examine the most favorable configuration. Furthermore, the charge separation and transfer mechanism of this heterojunction structure were discussed from the perspective of computation. Our study reveals that BPQDs and GCN formed a Type II heterojunction with a high stability and robust photocatalytic efficiency. Overall, the present work not only elucidates theoretical guidance for taking the merits of BPQDs and GCN, but also paves a new frontier for engineering metal free 0D/2D heterojunction nanocomposite systems.", "author_names": [ "Zhouzhou Kong", "Xingzhuo Chen", "Wee-Jun Ong", "Xiujian Zhao", "Neng Li" ], "corpus_id": 139971142, "doc_id": "139971142", "n_citations": 47, "n_key_citations": 0, "score": 0, "title": "Atomic level insight into the mechanism of 0D/2D black phosphorus quantum dot/graphitic carbon nitride (BPQD/GCN) metal free heterojunction for photocatalysis", "venue": "", "year": 2019 } ]

[ { "abstract": "In contrast to traditional semiconductors, conjugated polymers provide ease of processing, low cost, physical flexibility and large area coverage1. These active optoelectronic materials produce and harvest light efficiently in the visible spectrum. The same functions are required in the infrared for telecommunications (1,300 1,600 nm) thermal imaging (1,500 nm and beyond) biological imaging (transparent tissue windows at 800 nm and 1,100 nm) thermal photovoltaics >1,900 nm) and solar cells (800 2,000 nm) Photoconductive polymer devices have yet to demonstrate sensitivity beyond ~800 nm (refs 2,3) Sensitizing conjugated polymers with infrared active nanocrystal quantum dots provides a spectrally tunable means of accessing the infrared while maintaining the advantageous properties of polymers. Here we use such a nanocomposite approach in which PbS nanocrystals tuned by the quantum size effect sensitize the conjugated polymer poly[2 methoxy 5 (2' ethylhexyloxy p phenylenevinylene) (MEH PPV) into the infrared. We achieve, in a solution processed device and with sensitivity far beyond 800 nm, harvesting of infrared photogenerated carriers and the demonstration of an infrared photovoltaic effect. We also make use of the wavelength tunability afforded by the nanocrystals to show photocurrent spectra tailored to three different regions of the infrared spectrum.", "author_names": [ "Stephen A McDonald", "Gerasimos Konstantatos", "Shiguo Zhang", "Paul W Cyr", "Ethan J D Klem", "Larissa Levina", "Edward H Sargent" ], "corpus_id": 11957853, "doc_id": "11957853", "n_citations": 1585, "n_key_citations": 8, "score": 1, "title": "Solution processed PbS quantum dot infrared photodetectors and photovoltaics", "venue": "Nature materials", "year": 2005 }, { "abstract": "Colloidal quantum dots (CQDs) enable low cost, high performance optoelectronic devices including photovoltaics, photodetectors, LEDs, and lasers. Continuous wave lasing in the near infrared remains to be realized based on such materials, yet a solution processed NIR laser would be of use in communications and interconnects. In infrared quantum dots, long lived gain is hampered by a high rate of Auger recombination. Here, we report the use of perovskite shells, grown on cores of IR emitting PbS CQDs, and we thus reduce the rate of Auger recombination by up to 1 order of magnitude. We employ ultrafast transient absorption spectroscopy to isolate distinct Auger recombination phenomena and study the effect of bandstructure and passivation on Auger recombination. We corroborate the experimental findings with model based investigations of Auger recombination in various CQD core shell structures. We explain how the band alignment provided by perovskite shells comes close to the optimal required to suppress the Auger rate. These results provide a step along the path toward solution processed near infrared lasers.", "author_names": [ "Rafael Quintero-Bermudez", "Randy P Sabatini", "Marc Lejay", "Oleksandr Voznyy", "Edward H Sargent" ], "corpus_id": 206716110, "doc_id": "206716110", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Small Band Offset Perovskite Shells Increase Auger Lifetime in Quantum Dot Solids.", "venue": "ACS nano", "year": 2017 }, { "abstract": "Operating at room temperature, a solution processed photodetector with near infrared sensitivity would be a significant advancement towards industrial and scientific applications. Polymer inorganic quantum dot (QD) composites are attractive due to combination of the merits of polymeric and inorganic semiconductors in novel electronic and photonic systems. Inorganic QDs are highly suitable as infrared absorbers, and polymer bulk heterojunctions are attractive as solution processable diodes. Herein, we demonstrated a photodetector with a spectral response ranging from 300 nm to 1600 nm using a bulk heterojunction composite of a wide bandgap conjugated polymer with narrow bandgap PbS QDs. Operating at room temperature, the solution processed photodetectors exhibit a detectivity greater than 1010 cm Hz1/2 W 1 and an external quantum efficiency of over 80% in the visible region and 10% in the infrared region. All these device performances are comparable to those of their inorganic counterparts. Thus, our results demonstrate a simple way to fabricate uncooled solution processed broadband photodetectors.", "author_names": [ "Wenzhan Xu", "Hui Ren Peng", "Tao Zhu", "Chao Yi", "Lei Liu", "Xiong Gong" ], "corpus_id": 102496010, "doc_id": "102496010", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "A solution processed near infrared polymer: PbS quantum dot photodetectors", "venue": "", "year": 2017 }, { "abstract": "Abstract Colloidal PbS quantum dots (QDs) are promising candidates for various optoelectronic applications based on solution processed thin film techniques. In this work, a versatile layer by layer (LBL) spray deposition of the QDs is introduced aiming for a future large scale fabrication process of optoelectronic devices. As compared to spin coated QD solids, a smaller inter dot distance and a better ordered superlattice stacking behavior of the QDs are found in the spray deposited QD solids as confirmed by grazing incidence small angle X ray scattering (GISAXS) The spectral mapping combined time resolved photoluminescence analysis indicates a longer charge carrier lifetime and better order of the energy state distribution of the spray deposited QD solid comparing with the spin coated one. Thus, photodetectors based on spray deposition of QD solids demonstrate an excellent device performance, with the responsivity achieving 365.1 A/W and the detectivity reaching up to 1.4 x 1012 Jones under an illumination power of 63.5 mW/cm2 at a wavelength of 1250 nm. The spray deposited device performances indicate a great potential of spray deposition of large sized QDs in large scale fabrications for optoelectronics using longer wavelengths.", "author_names": [ "Wei-fang Chen", "Wei Chen", "Haodong Tang", "Yulong Chen", "Julian Eliah Heger", "Nian Li", "Lucas P Kreuzer", "Yue-Min Xie", "Depeng Li", "Carl J Anthony", "Zoe Pikramenou", "Kar Wei Ng", "Xiao Wei Sun", "Kai Wang", "Peter Muller-Buschbaum" ], "corpus_id": 224879441, "doc_id": "224879441", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Spray deposited PbS colloidal quantum dot solid for near infrared photodetectors", "venue": "", "year": 2020 }, { "abstract": "Harnessing low energy photons is of paramount importance for multi junction high efficiency solar cells as well as for thermo photovoltaic applications. However, semiconductor absorbers with the bandgap lower than 0.8 eV have been limited to III V (InGaAs) or IV (Ge) semiconductors that are characterized by high manufacturing costs and complicated lattice matching requirements in their growth and integration with higher bandgap cells. Here, we have developed solution processed low bandgap photovoltaic devices based on PbS colloidal quantum dots (CQDs) with a bandgap of 0.7 eV suited for both thermo photovoltaics and low energy solar photon harvesting. By matching the spectral response of those cells to that of the infrared solar spectrum, we report a record high short circuit current (JSC) of 37 mA cm 2 under the full solar spectrum and 5.5 mA cm 2 when placed at the back of a silicon wafer resulting in power conversion efficiencies (PCEs) of 6.4% and 0.7% respectively. Moreover, the device reached an above bandgap PCE of ~6% as a thermo photovoltaic cell recorded under a 1000 degC blackbody radiator.", "author_names": [ "Yu Bi", "Arnau Bertran", "Shuchi Gupta", "Inigo Ramiro", "Santanu Pradhan", "Sotirios Christodoulou", "Shanmukh Naidu Majji", "Mehmet Zafer Akgul", "Gerasimos Konstantatos" ], "corpus_id": 58555166, "doc_id": "58555166", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Solution processed infrared and thermo photovoltaics based on 0.7 eV bandgap PbS colloidal quantum dots.", "venue": "Nanoscale", "year": 2019 }, { "abstract": "Lead sulfide (PbS) colloidal quantum dot solar cells (CQDSCs) present the distinctive ability to utilize short wave infrared light, good ambient stability, and convenient solution based fabrication processes and thus attract much attention in the photovoltaic research field. The performance of CQDSCs has been improved by constructing the ZnO/PbS heterojunction, due to suitable band levels and electron mobility of ZnO electron transfer layer (ETL) However, the huge number of defects in low temperature processed ZnO cause an unbalanced carrier related processes, which restrict further performance enhancement and flexible production of CQDSCs. Here, we described a facile method to passivate defects in low temperature sol gel ZnO by introducing polyethylenimine (PEI) into the precursor solution. Versus the original ZnO film, the composite ZnO:PEI films exhibit better crystallization because of the Zn N interaction. A series of electronic analyses have shown that the addition of PEI reduces the work function", "author_names": [ "Lei Wang", "Yuwen Jia", "Yinglin Wang", "Shuaipu Zang", "Shengsheng Wei", "Jinhuan Li", "Xintong Zhang" ], "corpus_id": 139731045, "doc_id": "139731045", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Defect Passivation of Low Temperature Processed ZnO Electron Transport Layer with Polyethylenimine for PbS Quantum Dot Photovoltaics", "venue": "ACS Applied Energy Materials", "year": 2019 }, { "abstract": "Lead sulfide colloidal quantum dots (PbS CQDs) exhibit outstanding optoelectronic properties owing to their low temperature solution processability and bandgap tunability. PbS QD heterojunction detectors suffer from an incomplete interface and bulk passivation. Herein, a simple passivation method based on PbI2 was developed, which can effectively suppress the heterojunction interface and PbS QD surface defects by interface and ligand passivation. Utilizing the present strategies, PbS QD photodetectors can decrease the dark current and simultaneously increase the photocurrent. Such photodiode detectors also showed a fast response on the order of microseconds which is much faster than that of photoconductive CQD detectors (millisecond order) Also, an ultra high specific detectivity of 1013 Jones was obtained. Meanwhile, the energy conversion efficiency of PbI2 based devices reached 8% a twofold value compared to the control one. The convenient and efficient passivation method is expected to hold great potential for high performance QD optoelectronic devices.", "author_names": [ "Keke Qiao", "Yulin Cao", "Xiaokun Yang", "J Khan", "Hui Deng", "Jian Zhang", "Umar Farooq", "Shengjie Yuan", "Haisheng Song" ], "corpus_id": 103520632, "doc_id": "103520632", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Efficient interface and bulk passivation of PbS quantum dot infrared photodetectors by PbI2 incorporation", "venue": "", "year": 2017 }, { "abstract": "Abstract In this paper, we explore the impact of isopropylamine (IPAM) as a short ligand on a solution processed infrared photodetector and a photovoltaic device using lead sulfide (PbS) colloidal quantum dots. Original oleic acid capping is replaced by isopropylamine through a solution phase ligand exchange process. Then a blend of poly[2 methoxy 5 (2 ethylhexyloxy) 1,4 phenylenevinylene] or MEH PPV and the isopropylamine capped PbS colloidal quantum dots is prepared for a photosensitive layer sandwiched by two different electrodes. Results illustrate that contribution of isopropylamine can improve the responsivity of a photodetector and enhance the photovoltaic performance by increasing the open circuit voltage and short circuit current.", "author_names": [ "Taher Ghomian", "Samaneh Farimand", "Jin-Woo Choi" ], "corpus_id": 139450211, "doc_id": "139450211", "n_citations": 11, "n_key_citations": 1, "score": 0, "title": "The effect of isopropylamine capped PbS quantum dots on infrared photodetectors and photovoltaics", "venue": "", "year": 2017 }, { "abstract": "Lead sulfide colloidal quantum dots (PbS CQDs) exhibit outstanding optoelectronic properties owing to their low temperature solution processability and bandgap tunability. PbS QD heterojunction detectors suffer from an incomplete interface and bulk passivation. Herein, a simple passivation method based on PbI2 was developed, which can effectively suppress the heterojunction interface and PbS QD surface defects by interface and ligand passivation. Utilizing the present strategies, PbS QD photodetectors can decrease the dark current and simultaneously increase the photocurrent. Such photodiode detectors also showed a fast response on the order of microseconds which is much faster than that of photoconductive CQD detectors (millisecond order) Also, an ultra high specific detectivity of 10 Jones was obtained. Meanwhile, the energy conversion efficiency of PbI2 based devices reached 8% a twofold value compared to the control one. The convenient and efficient passivation method is expected to hold great potential for high performance QD optoelectronic devices.", "author_names": [ "Keke Qiao", "Yulin Cao", "Xiaokun Yang", "J Khan", "Hui Deng", "Jinshui Zhang", "Umar Farooq", "Shengjie Yuana", "Haisheng Song" ], "corpus_id": 201680708, "doc_id": "201680708", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "and bulk passivation of PbS quantum dot infrared photodetectors by PbI 2 incorporation", "venue": "", "year": 2017 }, { "abstract": "Solution processed semiconductors have opened promising avenues for next generation semiconductor and optoelectronic industries. Colloidal quantum dots (CQDs) as one of the typical materials are widely utilized for the design and development of light emission diodes, photodetectors and solar cells. Recently, an emerging process of PbS QDs ink has been employed to attain world record power conversion efficiency (PCE) by surface passivation using a PbI2 ligand to form PbI2 PbS as well as the process optimization in the field of photovoltaics. However, the bonding and debonding of the ligands on the surface of PbS QDs are dynamic reversible processes in an ink environment. The uncoordinated Pb2+ defects induced by un bonded PbS QDs serve as the recombination sites. Thus, the present ink process leaves much room for the enhancement by surface passivation of PbS QDs. Herein, we devise an efficient strategy with a supplementary phenethylammonium iodide (PEAI) ligand for the formation of the PEAI PbS interface in PbS QDs ink processed solar cells. This newly developed method can not only improve the passivation on QDs surface by iodine ions, but also simultaneously enhance the carrier collection efficiency by a graded energy alignment between PbI2 PbS and PEAI PbS layers. The corresponding power conversion efficiency (PCE) of the optimized device has significantly increased by approximately 20% more than the control device. As a result, such robust and efficient method regarded as a strategic candidate can overcome the bottleneck of imperfect passivation caused by large specific surface area and loose bonding ligands, eventually promoting industrial application of QDs.", "author_names": [ "Xiaokun Yang", "Ji Yang", "Muhammad Irfan Ullah", "Yong Xia", "Gui-jie Liang", "Song Wang", "Jianbing Zhang", "Hsien-Yi Hsu", "Haisheng Song", "Jiang Tang" ], "corpus_id": 221162538, "doc_id": "221162538", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Enhanced Passivation and Carrier Collection in Ink Processed PbS Quantum Dots Solar Cells via Supplementary Ligand Strategy.", "venue": "ACS applied materials interfaces", "year": 2020 } ]

[ { "abstract": "Visible light driven photochemistry has continued to attract heightened interest due to its capacity to efficiently harvest solar energy and its potential to solve the global energy crisis. Plasmonic nanostructures boast broadly tunable optical properties coupled with catalytically active surfaces that offer a unique opportunity for solar photochemistry. Resonant optical excitation of surface plasmons produces energetic hot electrons that can be collected to facilitate chemical reactions. This review sums up recent theoretical and experimental approaches for understanding the underlying photophysical processes in hot electron generation and discusses various electron transfer models on both plasmonic metal nanostructures and plasmonic metal/semiconductor heterostructures. Following that are highlights of recent examples of plasmon driven hot electron photochemical reactions within the context of both cases. The review concludes with a discussion about the remaining challenges in the field and future opportunities for addressing the low reaction efficiencies in hot electron induced photochemistry.", "author_names": [ "Yuchao Zhang", "Shuai He", "Wenxiao Guo", "Yue Hu", "Jiawei Huang", "Justin R Mulcahy", "Wei David Wei" ], "corpus_id": 5184354, "doc_id": "5184354", "n_citations": 458, "n_key_citations": 1, "score": 1, "title": "Surface Plasmon Driven Hot Electron Photochemistry.", "venue": "Chemical reviews", "year": 2018 }, { "abstract": "Photochemistry that can be driven at low incident photon flux on optically excited plasmonic nanoparticles is attracting increasing research interest because of the fundamental need to combine surface reaction and in situ spectroscopy as well as the opportunity that plasmon driven reactions may offer a pathway for efficient conversion of solar energy into fuel. In mechanistic studies of plasmon driven reactions to date, a great deal of emphasis is given to hot electron transfer. The results summarized in this Feature Article indicate that photochemistry on plasmonic nanoparticles can be induced by hot electron transfer from the nanoparticle to an unoccupied orbital of the adsorbate and/or by plasmon pumped electron transition from an occupied molecular orbital to an unoccupied molecular orbital of the adsorbate. The branching photochemical reaction of para aminothiophenol on the plasmonic gold surface depending on the presence of a cetyltrimethylammonium bromide surface ligand that influences the hot elec.", "author_names": [ "Tefera Entele Tesema", "Bijesh Kafle", "Terefe G Habteyes" ], "corpus_id": 104378318, "doc_id": "104378318", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Plasmon Driven Reaction Mechanisms: Hot Electron Transfer versus Plasmon Pumped Adsorbate Excitation", "venue": "The Journal of Physical Chemistry C", "year": 2019 }, { "abstract": "Hot electrons generated through plasmonic excitations in metal nanostructures show great promise for efficiently driving chemical reactions with light. However, the lifetime, yield, and mechanism of action of plasmon generated hot electrons involved in a given photocatalytic process are not well understood. Here, we develop ultrafast surface enhanced Raman scattering (SERS) as a direct probe of plasmon molecule interactions in the plasmon catalyzed dimerization of 4 nitrobenzenethiol to p,p' dimercaptoazobenzene. Ultrafast SERS probing of these molecular reporters in plasmonic hot spots reveals transient Fano resonances, which we attribute to near field coupling of Stokes shifted photons to hot electron driven metal photoluminescence. Surprisingly, we find that hot spots that yield more photoluminescence are much more likely to drive the reaction, which indirectly proves that plasmon generated hot electrons induce the photochemistry. These ultrafast SERS results provide insight into the relative reactivity of different plasmonic hot spot environments and quantify the ultrafast lifetime of hot electrons involved in plasmon driven chemistry.", "author_names": [ "Nathaniel C Brandt", "Emily L Keller", "Renee R Frontiera" ], "corpus_id": 19777456, "doc_id": "19777456", "n_citations": 55, "n_key_citations": 0, "score": 0, "title": "Ultrafast Surface Enhanced Raman Probing of the Role of Hot Electrons in Plasmon Driven Chemistry.", "venue": "The journal of physical chemistry letters", "year": 2016 }, { "abstract": "Direct measurement of hot electron flux from a plasmonic Schottky nanodiode is important for obtaining fundamental insights explaining the mechanism for electronic excitation on a surface. Here, we report the measurement of photoinduced hot electrons on a triangular Au nanoprism on TiO2 under incident light with photoconductive atomic force microscopy (pc AFM) which is direct proof of the intrinsic relation between hot electrons and localized surface plasmon resonance. We find that the local photocurrent measured on the boundary of the Au nanoprism is higher than that inside the Au nanoprism, indicating that field confinement at the boundary of the Au nanoprism acts as a hot spot, leading to the enhancement of hot electron flow at the boundary. Under incident illumination with a wavelength near the absorption peak (645 nm) of a single Au nanoprism, localized surface plasmon resonance resulted in the generation of a higher photoinduced hot electron flow for the Au nanoprism/TiO2, compared with that at a wavelength of 532 nm. We show that the application of a reverse bias results in a higher photocurrent for the Au nanoprism/TiO2, which is associated with a lowering of the Schottky barrier height caused by the image force. These nanoscale measurements of hot electron flux with pc AFM indicate efficient photon energy transfer mediated by surface plasmons in hot electron based energy conversion.", "author_names": [ "Hyunhwa Lee", "Hyunsoo Lee", "Jeong Y Park" ], "corpus_id": 206750180, "doc_id": "206750180", "n_citations": 34, "n_key_citations": 0, "score": 0, "title": "Direct Imaging of Surface Plasmon Driven Hot Electron Flux on the Au Nanoprism/TiO2.", "venue": "Nano letters", "year": 2019 }, { "abstract": "A continuous flow of hot electrons that are not at thermal equilibrium with the surrounding metal atoms is generated by the absorption of photons. Here we show that hot electron flow generated on a gold thin film by photon absorption (or internal photoemission) is amplified by localized surface plasmon resonance. This was achieved by direct measurement of photocurrent on a chemically modified gold thin film of metal semiconductor (TiO(2) Schottky diodes. The short circuit photocurrent obtained with low energy photons is consistent with Fowler's law, confirming the presence of hot electron flows. The morphology of the metal thin film was modified to a connected gold island structure after heating such that it exhibits surface plasmon. Photocurrent and optical measurements on the connected island structures revealed the presence of a localized surface plasmon at 550 20 nm. The results indicate an intrinsic correlation between the hot electron flow generated by internal photoemission and localized surface plasmon resonance.", "author_names": [ "Young Keun Lee", "Chan Ho Jung", "Jonghyurk Park", "Hyungtak Seo", "Gabor A Somorjai", "Jeong Y Park" ], "corpus_id": 20804230, "doc_id": "20804230", "n_citations": 234, "n_key_citations": 1, "score": 0, "title": "Surface plasmon driven hot electron flow probed with metal semiconductor nanodiodes.", "venue": "Nano letters", "year": 2011 }, { "abstract": "A pulse of high kinetic energy electrons (1 3 eV) in metals can be generated after surface exposure to external energy, such as the absorption of light or exothermic chemical processes. These energetic electrons are not at thermal equilibrium with the metal atoms and are called \"hot electrons\" The detection of hot electrons and understanding the correlation between hot electron generation and surface phenomena are challenging questions in the surface science and catalysis community. Hot electron flow generated on a gold thin film by photon absorption (or internal photoemission) appears to be correlated with localized surface plasmon resonance. In this perspective, we outline recent research activities to develop energy conversion devices based on hot electrons and surface plasmons. The chemicurrent or hot electron flows correlate well with the turnover rate of CO oxidation or hydrogen oxidation, measured separately by gas chromatography, suggesting an intrinsic relation between the catalytic reaction and hot electron generation. Photon energy can be directly converted to hot electron flow through the metal semiconductor interface of Pt/TiO2. The flow of hot charge carriers influences the chemistry at the oxide metal interface and the turnover rate in the chemical reaction on metal semiconductor nanostructures. The effect of surface plasmons on the catalytic and photocatalytic activity on metal oxide hybrid nanocatalysts is also highlighted.Graphical Abstract", "author_names": [ "Jeong Y Park", "Sun Mi Kim", "Hyosun Lee", "Brundabana Naik" ], "corpus_id": 95912372, "doc_id": "95912372", "n_citations": 40, "n_key_citations": 0, "score": 0, "title": "Hot Electron and Surface Plasmon Driven Catalytic Reaction in Metal Semiconductor Nanostructures", "venue": "Catalysis Letters", "year": 2014 }, { "abstract": "Abstract Nonradiative surface plasmon decay produces highly energetic electron hole pairs with desirable characteristics, but the measurement and harvesting of nonequilibrium hot holes remain challenging due to ultrashort lifetime and diffusion length. Here, the direct observation of LSPR driven hot holes created in a Au nanoprism/p GaN platform using photoconductive atomic force microscopy (pc AFM) is demonstrated. Significant enhancement of photocurrent in the plasmonic platforms under light irradiation is revealed, providing direct evidence of plasmonic hot hole generation. Experimental and numerical analysis verify that a confined |E| field surrounding a single Au nanoprism spurs resonant coupling between localized surface plasmon resonance (LSPR) and surface charges, thus boosting hot hole generation. Furthermore, geometrical and size dependence on the extraction of LSPR driven hot holes suggests an optimized pathway for their efficient utilization. The direct visualization of hot hole flow at the nanoscale provides significant opportunities for harnessing the underlying nature and potential of plasmonic hot holes.", "author_names": [ "Hyunhwa Lee", "Kyoungjae Song", "Moonsang Lee", "Jeong Y Park" ], "corpus_id": 225046974, "doc_id": "225046974", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "In Situ Visualization of Localized Surface Plasmon Resonance Driven Hot Hole Flux", "venue": "Advanced science", "year": 2020 }, { "abstract": "", "author_names": [ "Jeong Y Park", "Sun Mi Kim", "Hyosun Lee", "Brundabana Naik" ], "corpus_id": 196849970, "doc_id": "196849970", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Hot Electron and Surface Plasmon Driven Catalytic Reaction in Metal Semiconductor Nanostructures", "venue": "", "year": 2015 }, { "abstract": "", "author_names": [ "Sun Mi Kim", "" ], "corpus_id": 103741130, "doc_id": "103741130", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Surface oxide layer and hot electron and surface plasmon driven catalytic reaction pyomyeon sanhwaceunggwa hasjeonja mic pyomyeonpeulrajeumoni yudohaneun hwahagbaneung yeongu", "venue": "", "year": 2014 }, { "abstract": "Light driven synthesis of plasmonic metal nanostructures has garnered broad scientific interests. Although it has been widely accepted that surface plasmon resonance (SPR) generated energetic electrons play an essential role in this photochemical process, the exact function of plasmon generated hot holes in regulating the morphology of nanostructures has not been fully explored. Herein, we discover that those hot holes work with surface adsorbates collectively to control the anisotropic growth of gold (Au) nanostructures. Specifically, it is found that hot holes stabilized by surface adsorbed iodide enable the site selective oxidative etching of Au0, which leads to non uniform growths along different lateral directions to form six pointed Au nanostars. Our studies establish a molecular level understanding of the mechanism behind the plasmon driven synthesis of Au nanostars and illustrate the importance of cooperation between charge carriers and surface adsorbates in regulating the morphology evolution of plasmonic nanostructures.", "author_names": [ "Wenxiao Guo", "Aaron C Johnston-Peck", "Yuchao Zhang", "Yue Hu", "Jiawei Huang", "Wei David Wei" ], "corpus_id": 219173523, "doc_id": "219173523", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Cooperation of Hot Holes and Surface Adsorbates in Plasmon Driven Anisotropic Growth of Gold Nanostars.", "venue": "Journal of the American Chemical Society", "year": 2020 } ]

[ { "abstract": "Mathematical modelling of non linearity due to charge injection phenomenon with variation in desired characteristics of complementary metal oxide semiconductor (CMOS) image sensor (CIS) and correlated double sampling (CDS) circuits is presented. Existing suppression strategies of charge injection effect for CIS and CDS circuits lack in accuracy because of the absence of knowledge of its effect with variation in major device parameters related to switching transistors viz. width (W) length (L) sense node capacitance (Cpd and photon current (I ph) Therefore, variations in these parameters under the effect of charge injection have been experimentally studied. Based on the outcomes, it can be concluded that four parameter logistic regression symmetrical sigmoid function is the best fit for the non linearity introduced. Also, the devised mathematical model could be utilised as an activation function to train the biological neurons in CIS centred biomedical applications. A brief illustration of the same has been included for electrical stimulation of retinal cells. Further, the higher values of I ph, Cpd and scaling of switching transistors as W min and L L min can prove effective in reducing the non linearity. Contrary to previous studies, the higher value of Cpd utilising the normal photodiode found suitable for charge injection suppression in CIS.", "author_names": [ "Ashish Tiwari", "R H Talwekar" ], "corpus_id": 226301354, "doc_id": "226301354", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Analysis and mathematical modelling of charge injection effect for efficient performance of CMOS imagers and CDS circuit", "venue": "IET Circuits Devices Syst.", "year": 2020 }, { "abstract": "Since the introduction of SPICE non linear controlled voltage and current sources, they have become a central feature in the interactive development of behavioural device models and circuit macromodels. The current generation of SPICE based open source general public license circuit simulators, including Qucs, Ngspice and Xyce(c) implements a range of mathematical operators and functions for modelling physical phenomena and system performance. The Qucs equation defined device is an extension of the SPICE style non linear B type controlled source which adds dynamic charge properties to behavioural sources, allowing for example, voltage and current dependent capacitance to be easily modelled. Following, the standardization of Verilog A, it has become a preferred hardware description language where analogue models are written in a netlist format combined with more general computer programming features for sequencing and controlling model operation. In traditional circuit simulation, the generation of a Verilog A model from a schematic, with embedded non linear behavioural sources, is not automatic but is normally undertaken manually. This paper introduces a new approach to the generation of Verilog A compact device models from Qucs circuit schematics using a purpose built analogue module synthesizer. To illustrate the properties and use of the Qucs Verilog A module synthesiser, the text includes a number of semiconductor device modelling examples and in some cases compares their simulation performance with conventional behavioural device models. Copyright (c) 2016 John Wiley Sons, Ltd.", "author_names": [ "Mike Brinson", "Vadim Kuznetsov" ], "corpus_id": 61322401, "doc_id": "61322401", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "A new approach to compact semiconductor device modelling with Qucs Verilog A analogue module synthesis", "venue": "", "year": 2016 }, { "abstract": "In this paper, concepts of mathematics and computer science were applied to electronics engineering field, specifically very large scale integration (VLSI) design and semiconductor industry. Presently one of the major challenges faced by the semiconductor industry is continuously growing leakage current with technology scaling. Transistor is the smallest structural unit of any chip or semiconductor device. Subthreshold leakage current is known as one of the most dominant leakage current components of transistor. In this paper, mathematical relationship between transistor structure and subthreshold leakage current was found. An algorithm was designed for automatic tracking of the transistor structure. Simulation setup was formed by applying some mathematical formula on the outputs of the algorithm. Results of TCAD software simulation were found to be very close to a well known mathematical formula. As complementary metal oxide semiconductor (CMOS) is the most popular technology for semiconductor device fabrication in present days, the same was used for simulation purpose.", "author_names": [ "D Mukherjee", "B V Ramana Reddy" ], "corpus_id": 57590534, "doc_id": "57590534", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Algorithm design, software simulation and mathematical modelling of subthreshold leakage current in CMOS circuits", "venue": "", "year": 2018 }, { "abstract": "the output voltage from the sustainable energy like photovoltaic (PV) arrays and fuel cells will be at less amount of level. This must be boost considerably for practical utilization or grid connection. A conventional boost converter will provides low voltage gain while Quadratic boost converter (QBC) provides high voltage gain. QBC is able to regulate the output voltage and the choice of second inductor can give its current as positive and whereas for boost increases in the voltage will not able to regulate the output voltage. It has low semiconductor device voltage stress and switch usage factor is high. Analysis and design modelingof Quadratic boost converter is proposed in this paper. A power with 200 W is developed with 12 V input voltage and yield 60 V output voltage and the outcomes are approved through recreation utilizing MATLAB/SIMULINK MODEL. Keywords Quadratic Boost converter (QBC) Photovoltaic (PV) DC DC converter.", "author_names": [ "Surya Prabha" ], "corpus_id": 221663331, "doc_id": "221663331", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Mathematical modelling and Performance analysis of Quadratic Boost Converter", "venue": "", "year": 2018 }, { "abstract": "The aim of the proposed paper is discussing problematics related to the thermal modelling of power electronic components. More in detail, the electro thermal relationship is investigated for the selected power diode, while analysis shall serve for system optimization considering thermal performance with the use of highly accurate 3D simulation model. The presented approach describes the procedure of the simulation model development, whereby the main part is discussing necessities relevant for material property identification through the indirect procedure, i.e, material properties are not known from the manufacturer. Electro thermal dependencies are defined within the proposed model, while this model enables parametric changes of the geometrical properties of the device. Added value of this procedure is the possibility of its use in exact determination of the lifetime of a semiconductor component using mathematical models taking into account operational variables (current, voltage, temperature, etc. The proposed model is verified and validated through thermovision experimental measurements within defined operational conditions.", "author_names": [ "Miroslav Pavelek", "Michal Frivaldsky", "Peter Sojka", "Jan Morgos" ], "corpus_id": 219004793, "doc_id": "219004793", "n_citations": 1, "n_key_citations": 0, "score": 1, "title": "Electro Thermal Modelling and Experimental Verification of Power Semiconductor Diode", "venue": "", "year": 2020 }, { "abstract": "Overview and physical equations. Overview of device modelling. Quantum mechanics. Equilibrium thermodynamics and statistical mechanics. Density of states and applications 1. Density of states and applications 2. The transport equations and the device equations. Mathematical and numerical methods. Basic approximation and numerical methods. Fermi and associated integrals. The upwinding method. Solution of equations: the Newton and reduced method. Solution of equations: the phaseplane method. Solution of equations: the multigrid method. Approximate and numerical solutions of the Schrodinger equation. Genetic algorithms and simulated annealing. Grid generation.", "author_names": [ "Eric A B Cole" ], "corpus_id": 118403174, "doc_id": "118403174", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Mathematical and Numerical Modelling of Heterostructure Semiconductor Devices: From Theory to Programming", "venue": "", "year": 2009 }, { "abstract": "A mathematical model describing the coupling of electrical, optical and thermal effects in semiconductor lasers is introduced. Through a systematic asymptotic expansion, the governing system of differential equations is reduced to a single second order boundary value problem. This highly nonlinear equation describes the time independent maximum temperature in the boundary layer adjacent to the mirror facet. The solution of the problem is a multi valued function of current. The graph of the maximum steady state temperature as a function of current gives a fold shaped response curve, which indicates that no bounded steady state exists beyond a critical value of current. For certain device parameters and initial conditions, thermal runaway occurs. A mechanism for the sudden mode of semiconductor laser failure is described in terms of thermal runaway.", "author_names": [ "W R Smith" ], "corpus_id": 54573628, "doc_id": "54573628", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Mathematical modelling of thermal runaway in semiconductor laser operation", "venue": "", "year": 2000 }, { "abstract": "Fermi integrals arise in the mathematical and numerical modelling of microwave semiconductor devices. In particular, associated Fermi integrals involving two arguments arise in the modelling of HEMTs, in which quantum wells form at the material interfaces. The numerical evaluation of these associated integrals is time consuming. In this paper, these associated integrals are replaced by simpler functions which depend on a small number of optimal parameters. These parameters are found by optimizing a suitable cost function using a genetic algorithm with simulated annealing. A new method is introduced whereby the transition probabilities of the simulated annealing process are based on the Bose Einstein distribution function, rather than on the more usual Maxwell Boltzmann statistics or Tsallis statistics. Results are presented for the simulation of a four layer HEMT, and show the effect of the approximation for the associated Fermi integrals. A comparison is made of the convergence properties of the three different statistics used in the simulated annealing process. Copyright (c) 2007 John Wiley Sons, Ltd.", "author_names": [ "Eric A B Cole" ], "corpus_id": 123041607, "doc_id": "123041607", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Integral evaluation in semiconductor device modelling using simulated annealing with Bose Einstein statistics", "venue": "", "year": 2007 }, { "abstract": "Fermi integrals arise in the mathematical and numerical modelling of microwave semiconductor devices. In particular, associated Fermi integrals involving two arguments arise in the modelling of HEMTs, in which quantum wells form at the material interfaces. The numerical evaluation of these associated integrals is time consuming. In this paper, these associated integrals are replaced by simpler functions which depend on a small number of optimal parameters. These parameters are found by optimizing a suitable cost function using a genetic algorithm with simulated annealing. A new method is introduced whereby the transition probabilities of the simulated annealing process are based on the Bose Einstein distribution function, rather than on the more usual Maxwell Boltzmann statistics or Tsallis statistics. Results are presented for the simulation of a four layer HEMT, and show the effect of the approximation for the associated Fermi integrals. A comparison is made of the convergence properties of the three different statistics used in the simulated annealing process. Copyright (c) 2007 John Wiley Sons, Ltd.", "author_names": [ "Eric A B Cole" ], "corpus_id": 124831110, "doc_id": "124831110", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Integral evaluation in semiconductor device modelling using simulated annealing with Bose Einstein statistics: Research Articles", "venue": "", "year": 2007 }, { "abstract": "In this paper mathematical and computational aspects of device modelling are treated. Four main subjects are discussed; the analytical model, the discretizations, the non linear and the linear systems of equations. On the one hand the most commonly used numerical techniques are described; on the other hand several new techniques are presented. Noteworthy new techniques are the generalized upwind box scheme and the mixed variable approach. Aspects such as the choice of variables and the singularly perturbed nature of the problem are treated. Properties of the matrices involved are presented in a systematic way. Throughout the paper a standard one dimensional diode is used to illustrate the concepts involved. Finally several realistic two dimensional examples are given.", "author_names": [ "S J Polak", "Cornelis den Heijer", "Wha Wil Schilders", "Peter A Markowich" ], "corpus_id": 122792889, "doc_id": "122792889", "n_citations": 149, "n_key_citations": 1, "score": 0, "title": "Semiconductor device modelling from the numerical point of view", "venue": "", "year": 1987 } ]

[ { "abstract": "Abstract A full swing high speed hybrid Full Adder (FA) cell based on Gate Diffusion Input (GDI) technique and Conventional Complementary Metal Oxide Semiconductor (CCMOS) logic has been proposed in this work. The design has been verified and compared with ten existing state of the art FAs to validate its performance. Simulations were conducted using Cadence Computer Aided Design (CAD) tool in 45 nm CMOS process. The proposed design shows significant performance improvement in terms of speed and Power Delay Product (PDP) To evaluate performance parameters in large structures, the FAs have been cascaded and extended up to 32 bits. The proposed design, along with five out of ten existing designs worked flawlessly when extended to 32 bits. However, the proposed design achieved the best performance parameters in large cascaded circuits.", "author_names": [ "Mehedi Hasan", "Hasan U Zaman", "Mainul Hossain", "Parag Biswas", "Sharnali Islam" ], "corpus_id": 225696739, "doc_id": "225696739", "n_citations": 11, "n_key_citations": 1, "score": 0, "title": "Gate Diffusion Input technique based full swing and scalable 1 bit hybrid Full Adder for high performance applications", "venue": "", "year": 2020 }, { "abstract": "Gate diffusion input (GDI) method using a simple cell makes it possible to design low power logic gates with reduced chip area and less complexity. In this work, a novel design of single bit optimized reversible logic based magnitude arithmetic unit (RMAU) circuit, using appropriate standard reversible gates with carbon nanotube (CNT) field effect transistors (CNTFETs) based on modified GDI (m GDI) method for nanoscales is presented. In order to optimize the performance of the proposed circuit, and to achieve minimum power consumption and propagation delay, transistor sizes are adjusted using the non dominated sorting genetic algorithm II (NSGA II) in MATLAB tool. The simulation results show improvement in evaluating the figure of merits in worst case delay and power consumption of the proposed optimized arithmetic unit, in comparison with a non optimized RMAU circuit using a similar design method but counterpart structures. The effects of different process parameters (such as the diameter of CNTs) and voltage and temperature (PVT) variations are extensively evaluated by the Monte Carlo procedure in standard 32 nm technology utilizing the Synopsys HSPICE simulator. According to the outcomes obtained, the proposed optimized RMAU circuit is robust against PVT variations and noise tolerable criterions, compared to those competitors with similar design in non optimized conditions. The proposed optimized and non optimized circuits were used in image processing as real environment assessments, and results depicted their excellent ability in being implemented in various large reversible based applications, such as future generations of FPGA chips and CNTFET based computers.", "author_names": [ "Ebrahim Abiri", "Abdolreza Darabi", "Mohammad Reza Salehi", "Ayoub Sadeghi" ], "corpus_id": 216345413, "doc_id": "216345413", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Optimized Gate Diffusion Input Method Based Reversible Magnitude Arithmetic Unit Using Non dominated Sorting Genetic Algorithm II", "venue": "Circuits Syst. Signal Process.", "year": 2020 }, { "abstract": "The priority encoder finds its wide scope as microprocessor interrupt controllers in digital and computer systems, where they classify the highest priority input. A Priority level is assigned to every input. The currently active input that has the highest importance agrees well with the output. A proficient implementation of 4 bit priority encoder using the modified gate diffusion input technique has been proposed in this research work. A simulation was carried out using Cadence 180 nm technology comparison made with complementary CMOS and Modified Gate Diffusion Input technique quality test matrices. This technique is much higher in speed and is a technique with limited power consumption", "author_names": [ "Radha N", "R Dagineeshwari", "B Devadharshini" ], "corpus_id": 219591160, "doc_id": "219591160", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "A Modified Gate Diffusion Input Technique Based Proficient 4 Bit Priority Encoder", "venue": "2020 International Conference on Inventive Computation Technologies (ICICT)", "year": 2020 }, { "abstract": "Gate Diffusion Input (GDI) is a technique of low power combinational circuit design. Complex logic functions like F1, F2, OR, AND, MUX and NOT can be implemented using just two transistors. GDI reduces area, propagation delay and power consumption of digital circuits, and has lower logic complexity than traditional CMOS and existing pass transistor logic techniques. Low power dissipation is achieved by reducing transistor count. Reducing area lowers the interconnect effects. In this paper, first the logic gates (GDI and CMOS) were implemented in Cadence in 90 nm and gate libraries were created for these. To estimate the complexity and scalability of GDI, ISCAS 85 benchmark circuits were synthesized using these libraries and compared in terms of area, power and delay. GDI circuits prove to be better in terms of area and power than their CMOS counterparts though slightly slower. They may be made faster by buffering logic after every few stages.", "author_names": [ "Utsav Vasudevan", "U B Meghana", "Deepali Koppad", "S Vignesh", "M Sowjanya" ], "corpus_id": 232316082, "doc_id": "232316082", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design of Digital Circuit Implementations Using Gate Diffusion Input and CMOS", "venue": "2020 IEEE 7th Uttar Pradesh Section International Conference on Electrical, Electronics and Computer Engineering (UPCON)", "year": 2020 }, { "abstract": "This paper presents a novel approach to the design of Null Convention Logic threshold gates using Gate Diffusion Input design methodology. Power and delay are the metrics of comparison between the proposed Gate Diffusion Input based Null Convention Logic gates and the conventional Null Convention Logic gates developed in literature. The efficiency of the proposed gates is illustrated by the design and simulation of NCL threshold gates using FSGDI and comparing the same with conventional static CMOS gates. The proposed FSGDI NCL gates offered 37% 23% and 44% reduction in average power, average delay and average power delay product. Keywords: FSGDI, full swing gate diffusion input, gate diffusion input, GDI, low power, NCL, NCL threshold gates, null convention logic Cite this Article: Anitha Juliette Albert, Murugan R. Muthammal R. Full swing gate diffusion input based NCL threshold gates. International Journal of Mobile Computing Devices. 2020; 6(1) 13 20p.", "author_names": [ "Anitha Juliette Albert", "R Bala Murugan", "Ramula Muthammal" ], "corpus_id": 225489794, "doc_id": "225489794", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Full Swing Gate Diffusion Input Based NCL Threshold Gates", "venue": "", "year": 2020 }, { "abstract": "Multi threshold null convention logic (MTNCL) is a novel low power paradigm for designing asynchronous null convention logic (NCL) circuits. To further reduce the dynamic power consumption, a new methodology that utilizes gate diffusion input technique is proposed. The proposed approach is used to realize MTNCL gates and a decrease in the transistor count is observed that tend to reduce the dynamic power consumption. Compared to SMTNCL approach, the proposed methodology shows a 5.6% is reduction in the power consumption for the MTNCL gates.", "author_names": [ "Prashanthi Metku", "Minsu Choi", "Yong-bin Kim" ], "corpus_id": 231825341, "doc_id": "231825341", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Gate Diffusion Input Multi Threshold Null Convention Logic Circuit Design Approach", "venue": "2020 International SoC Design Conference (ISOCC)", "year": 2020 }, { "abstract": "Low Power Fin Field Effect Transistor Based Combinational Circuits Design Using Gate Diffusion Input Method Thamizhpriya Muthamizhselvan and Krithiga Sukumaran 1 PG ScholarApplied Electronics, Thanthai Periyar Government Institute of Technology Vellore, T. N India 2 Assistant Professor, Department of ECE, Thanthai Periyar Government Institute of Technology Vellore, T. N India E mail: [email protected], [email protected]", "author_names": [ "Thamizhpriya Muthamizhselvan", "Krithiga Sukumaran" ], "corpus_id": 214720005, "doc_id": "214720005", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Low Power Fin Field Effect Transistor Based Combinational Circuits Design Using Gate Diffusion Input Method", "venue": "", "year": 2020 }, { "abstract": "The rapid growth in the use of portable systems has sparked research and development in the field of microelectronics especially for power consumption. Since battery technology does not match the speed of microelectronics, Low power technology has become an important technological factor. MGDI is a minimum power architecture design, which is quite a Gate Diffusion Input (GDI) change and is the lowest design method optimal for rapid, low power circuitry model using a reduced number of a transistor. Here, primitive cells AND, OR, and XOR gates, full adders, full subtractors, and 4x4 multiplier have been proposedusing the 180nm technology dependent MGDI in Cadence Virtuoso device. The main downside associated with GDI is that this strategy cannot resolve the bulk terminal which is not sufficiently biased. So that the number transistor count and delay will be reduced.", "author_names": [ "S N", "Radha N" ], "corpus_id": 225603523, "doc_id": "225603523", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design and Implementation of Primitive Cells, Full Adder, Full Subtractor, and Multiplier using Modified Gate Diffusion Input Logic", "venue": "2020 International Conference on Electronics and Sustainable Communication Systems (ICESC)", "year": 2020 }, { "abstract": "GDI technique allows minimization of area and power consumption of digital circuits. The reversible gate preserves same parity between output and input vectors is called fault tolerant but the dimension should be 3. In this design, Peres Gate is designed using Gate Diffusion Input using 8 transistors. The proposed new Peres Gate is used to design full adder with power efficient and fault tolerant. In this work power consumption 51.62mW is achieved for supply voltage 1V and the total area is 492mm2. The schematic is designed in DSCH 2 and layout is done in Microwind 2.", "author_names": [ "Somashekhar Malipatil", "Avinash Gour", "Vikas Maheshwari" ], "corpus_id": 228093355, "doc_id": "228093355", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Fault Tolerant Reversible Full Adder Design Using Gate Diffusion Input", "venue": "2020 International Conference on Smart Technologies in Computing, Electrical and Electronics (ICSTCEE)", "year": 2020 }, { "abstract": "Gate diffusion input (GDI) is a new technology of digital circuit design for low power. Compared with traditional CMOS technology, GDI technology can reduce the power consumption, the propagation delay and the circuit area. This work uses the GDI technology to build a 16 bit arithmetic logic unit (ALU) to perform logic operations (AND, OR, NAND and XOR) and math operations (addition, subtraction, adding 1 and subtracting 1) and finally compares it with traditional CMOS circuits.", "author_names": [ "Yihang Duanmu", "Jianguo Yang", "Jinbao Li", "Xiaoyong Xue", "Ming-e Jing", "Xiaoyang Zeng" ], "corpus_id": 229374070, "doc_id": "229374070", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "A 16 bit Arithmetic Logic Unit Design by Using Gate Diffusion Input", "venue": "2020 IEEE 15th International Conference on Solid State Integrated Circuit Technology (ICSICT)", "year": 2020 } ]

[ { "abstract": "The increasing demand for light emitting diodes (LEDs) has been driven by a number of application categories, including display backlighting, communications, medical services, signage, and general illumination. The construction of LEDs is somewhat similar to microelectronics, but there are functional requirements, materials, and interfaces in LEDs that make their failure modes and mechanisms unique. This paper presents a comprehensive review for industry and academic research on LED failure mechanisms and reliability to help LED developers and end product manufacturers focus resources in an effective manner. The focus is on the reliability of LEDs at the die and package levels. The reliability information provided by the LED manufacturers is not at a mature enough stage to be useful to most consumers and end product manufacturers. This paper provides the groundwork for an understanding of the reliability issues of LEDs across the supply chain. We provide an introduction to LEDs and present the key industries that use LEDs and LED applications. The construction details and fabrication steps of LEDs as they relate to failure mechanisms and reliability are discussed next. We then categorize LED failures into thirteen different groups related to semiconductor, interconnect, and package reliability issues. We then identify the relationships between failure causes and their associated mechanisms, issues in thermal standardization, and critical areas of investigation and development in LED technology and reliability.", "author_names": [ "Moon-Hwan Chang", "Diganta Das", "P V Varde", "Michael G Pecht" ], "corpus_id": 1741153, "doc_id": "1741153", "n_citations": 551, "n_key_citations": 13, "score": 1, "title": "Light emitting diodes reliability review", "venue": "Microelectron. Reliab.", "year": 2012 }, { "abstract": "Abstract This paper reviews the rapid progress being made in the developments of organic/inorganic blue light emitting diodes (LEDs) Blue LEDs exhibits outstanding electrical and optical properties such as low forward driving voltage, high light output power, high brightness and high internal quantum efficiency (IQE) This article highlights the rapid advancements being made in the developments of organic/inorganic blue LEDs over the last five decades, efficiency enhancement techniques, efficiency droop in blue LEDs and the techniques to alleviate efficiency droop, recent developments in flexible blue LEDs, degradation mechanisms and reliability issues in blue LEDs, challenges in fabrication and packaging of blue LEDs and it also throw light on the applications of blue LEDs. Their uniqueness in terms of low forward driving voltage, high light output power and brightness and large modulation bandwidth has fuelled the incorporation of blue LEDs in a wide variety of applications such as visible light communication (VLC) solid state lighting (SSL) cellular phone displays, liquid crystal display backlights, flexible flat panel displays, outdoor full colour displays, indicators, smart TVs, projection displays and implantable biomedical devices.", "author_names": [ "Maidhily Manikandan", "D Nirmal", "J Ajayan", "P MohanKumar", "P Prajoon", "L Arivazhagan" ], "corpus_id": 209988273, "doc_id": "209988273", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "A review of blue light emitting diodes for future solid state lighting and visible light communication applications", "venue": "", "year": 2019 }, { "abstract": "This chapter presents an extensive review of the literature on the degradation processes of GaN based UV A, UV B, and UV C LEDs. For the state of the art devices, the main open issue is the increase in Shockley Read Hall non radiative recombination inside the quantum well, originating from local generation of defects or from diffusion processes of dopant atoms or foreign impurities. Temperature acts as a significant acceleration factor, especially in lower wavelength devices, affected by a higher turn on voltage. Changes in the chemical structure of the package and of the encapsulant, induced by the high energy of the photons, may lead to a lower reflectivity and transmittance, thus limiting the overall reliability of the devices.", "author_names": [ "Carlo De Santi", "Desiree Monti", "Pradip Dalapati", "Matteo Meneghini", "Gaudenzio Meneghesso", "Enrico Zanoni" ], "corpus_id": 139655471, "doc_id": "139655471", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Reliability of Ultraviolet Light Emitting Diodes", "venue": "", "year": 2019 }, { "abstract": "Abstract Currently, the major commercial white light emitting diode is the phosphor converted LED made of blue emitting chip and Y 3 Al 5 O 12 :Ce 3+ yellow phosphor dispersed in organic silicone. However, the organic binder in high power device ages easily and turns yellow due to accumulated heat emitted from chip, which adversely affects the device properties such as luminous efficacy and color coordination, and therefore reduces its long term reliability as well as lifetime. In this mini review article, we provide an overview of recent progresses in developing transparent inorganic glass ceramics phosphors excitable by blue chip, as an alternative to conventional polymer based phosphor converter, for construction of high power white light emitting diodes. Two kinds of synthesis routes, glass crystallization and low temperature co sintering, are discussed in detail. Afterwards, the materials design, structure/property optimization as well as glass ceramic based WLED devices construction are summarized. Finally, challenges and future advances for the realization of transparent glass ceramics in commercial applications will be presented.", "author_names": [ "Daqin Chen", "Weidong Xiang", "Xiaojuan Liang", "Jiasong Zhong", "Hua Yu", "Mingye Ding", "Hongwei Lu", "Zhen-guo Ji" ], "corpus_id": 136588252, "doc_id": "136588252", "n_citations": 354, "n_key_citations": 0, "score": 0, "title": "Advances in Transparent Glass Ceramic Phosphors for White Light Emitting Diodes A Review", "venue": "", "year": 2015 }, { "abstract": "<jats:p><jats:fig position=\"anchor\"<jats:graphic xmlns:xlink=\"http:/www.w3.org/1999/xlink\" mime subtype=\"png\" mimetype=\"image\" position=\"float\" xlink:href=\"S0884291419003315_figAb.png\" /jats:fig>/jats:p>", "author_names": [ "Yun Li", "Kun Cao", "Rong Chen" ], "corpus_id": 210255915, "doc_id": "210255915", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Thin film encapsulation for the organic light emitting diodes display via atomic layer deposition", "venue": "Journal of Materials Research", "year": 2019 }, { "abstract": "Organic light emitting diode (LED) technology has reached a point where performance levels are adequate for a number of applications. This review examines the key scientific issues that underlie the operation of such LEDs. The most advanced LEDs are multilayer devices, with the different layers possessing specialized carrier transport/optical properties. A combination of these materials results in the highly efficient devices that have now been reported by several laboratories. The important issue of reliability and some possible applications for organic LEDs are surveyed.", "author_names": [ "Ananth Dodabalapur" ], "corpus_id": 221894468, "doc_id": "221894468", "n_citations": 156, "n_key_citations": 0, "score": 0, "title": "Organic light emitting diodes", "venue": "", "year": 1997 }, { "abstract": "A review is presented of the operation and characteristics of electroluminescent p n junctions which are specifically designed for incoherent emission in the visible region of the optical spectrum. Recombination mechanisms in direct and indirect bandgap semiconductors, optical losses and reliability, efficiency and brightness considerations, and material synthesis are treated in sufficient depth to understand their role in the over all performance of visible light emitting diodes (LEDs) The paper is concluded with a summary of the state of the art for each of the various types of LEDs presently under development or commercially available.", "author_names": [ "Charles J Nuese", "Henry Kressel", "Ivan Ladany" ], "corpus_id": 97850512, "doc_id": "97850512", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Light Emitting Diodes and Semiconductor Materials for Displays", "venue": "", "year": 1973 }, { "abstract": "Lead halide perovskites are a remarkable class of materials that have emerged over the past decade as being suitable for application in a broad range of devices, such as solar cells, light emitting diodes, lasers, transistors, and memory devices, among others. While they are often solution processed semiconductors deposited at low temperatures, perovskites exhibit properties one would only expect from highly pure inorganic crystals that are grown at high temperatures. This unique phenomenon has resulted in fast paced progress toward record device performance; unfortunately, the basic science behind the remarkable nature of these materials is still not well understood. This review assesses the current understanding of the photoluminescence (PL) properties of metal halide perovskite materials and highlights key areas that require further research. Furthermore, the need to standardize the methods for characterization of PL in order to improve comparability, reliability and reproducibility of results is emphasized.", "author_names": [ "Katelyn P Goetz", "Alexander D Taylor", "Fabian Paulus", "Yana Vaynzof" ], "corpus_id": 216506997, "doc_id": "216506997", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Shining Light on the Photoluminescence Properties of Metal Halide Perovskites", "venue": "", "year": 2020 }, { "abstract": "Currently available reliability test standards (and specifications) for LED packages and systems have mainly been focused on the evaluation of lumen maintenance lifetimes. A brief review on these published standards is given in Sect. 4.1. Then some advanced methods for LED lumen maintenance lifetime estimation by taking into the statistical effects into account are discussed in Sect. 4.2. Afterward Sects. 4.3 and 4.4 in which part of the materials are excerpted from reference (Qian et al. Reliab. Eng. Syst. Saf. 147:84 92, 2016; Qian et al. Prediction of Lumen Depreciation and Color Shift for Phosphor converted White Light Emitting Diodes Based on a Spectral Power Distribution Analysis Method, IEEE Access, to Be Published, (n.d. present two of the hot topics in the reliability field. In Sect. 4.3, a temperature driven accelerated test method within 2000 h is proposed instead of the 6000 h test methods to qualify the LED luminaires and lamps with an expected lumen maintenance lifetime of 25,000 h. And in Sect. 4.4, a spectral power distribution (SPD) analysis based method is proposed to simultaneously predict the lumen depreciation and color shift of phosphor converted white LEDs (pc LEDs) In the end, concluding remarks of this chapter are summarized in Sect. 4.5.", "author_names": [ "Cheng Qian", "J J Fan", "Xuejun Fan", "Guoqi Zhang" ], "corpus_id": 195949554, "doc_id": "195949554", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Advances in Reliability Testing and Standards Development for LED Packages and Systems", "venue": "", "year": 2018 }, { "abstract": "We review the failure modes and mechanisms of gallium nitride (GaN) based light emitting diodes (LEDs) A number of reliability tests are presented, and specific degradation mechanisms of state of the art LED structures are analyzed. In particular, we report recent results concerning the following issues: 1) the degradation of the active layer induced by direct current stress due to the increase in nonradiative recombination; 2) the degradation of LEDs submitted to reverse bias stress tests; 3) the catastrophic failure of advanced LED structures related to electrostatic discharge events; 4) the degradation of the ohmic contacts of GaN based LEDs; and 5) the degradation of the optical properties of the package/phosphors system of white LEDs. The presented results provide important information on the weaknesses of LED technology and on the design of procedures for reliability evaluation. Results are compared with literature data throughout the text.", "author_names": [ "Matteo Meneghini", "Augusto Tazzoli", "Giovanna Mura", "Gaudenzio Meneghesso", "Enrico Zanoni" ], "corpus_id": 22899725, "doc_id": "22899725", "n_citations": 216, "n_key_citations": 8, "score": 0, "title": "A Review on the Physical Mechanisms That Limit the Reliability of GaN Based LEDs", "venue": "IEEE Transactions on Electron Devices", "year": 2010 } ]

[ { "abstract": "A fundamental aim in the field of catalysis is the development of new modes of small molecule activation. One approach toward the catalytic activation of organic molecules that has received much attention recently is visible light photoredox catalysis. In a general sense, this approach relies on the ability of metal complexes and organic dyes to engage in single electron transfer (SET) processes with organic substrates upon photoexcitation with visible light. Many of the most commonly employed visible light photocatalysts are polypyridyl complexes of ruthenium and iridium, and are typified by the complex tris(2,2' bipyridine) ruthenium(II) or Ru(bpy)32+ (Figure 1) These complexes absorb light in the visible region of the electromagnetic spectrum to give stable, long lived photoexcited states.1,2 The lifetime of the excited species is sufficiently long (1100 ns for Ru(bpy)32+ that it may engage in bimolecular electron transfer reactions in competition with deactivation pathways.3 Although these species are poor single electron oxidants and reductants in the ground state, excitation of an electron affords excited states that are very potent single electron transfer reagents. Importantly, the conversion of these bench stable, benign catalysts to redox active species upon irradiation with simple household lightbulbs represents a remarkably chemoselective trigger to induce unique and valuable catalytic processes. Figure 1 Ruthenium polypyridyl complexes: versatile visible light photocatalysts. The ability of Ru(bpy)32+ and related complexes to function as visible light photocatalysts has been recognized and extensively investigated for applications in inorganic and materials chemistry. In particular, photoredox catalysts have been utilized to accomplish the splitting of water into hydrogen and oxygen4 and the reduction of carbon dioxide to methane.5 Ru(bpy)32+ and its analogues have been used (i) as components of dye sensitized solar cells6 and organic light emitting diodes,7 (ii) to initiate polymerization reactions,8 and (iii) in photo dynamic therapy.9 Until recently, however, these complexes had been only sporadically employed as photocatalysts in the area of organic synthesis. The limited exploration of this area is perhaps surprising, as single electron, radical processes have long been employed in C C bond construction and often provide access to reactivity that is complementary to that of closed shell, two electron pathways.10 In 2008, concurrent reports from the Yoon group and our own lab detailed the use of Ru(bpy)32+ as a visible light photoredox catalyst to perform a [2 2] cycloaddition11 and an a alkylation of aldehydes,12 respectively. Shortly thereafter, Stephenson and co workers disclosed a photoredox reductive dehalogenation of activated alkyl halides mediated by the same catalyst.13 The combined efforts of these three research groups have helped to initiate a renewed interest in this field, prompting a diversity of studies into the utility of photoredox catalysis as a conceptually novel approach to synthetic organic reaction development. Much of the promise of visible light photoredox catalysis hinges on its ability to achieve unique, if not exotic bond constructions that are not possible using established protocols. For instance, photoredox catalysis may be employed to perform overall redox neutral reactions. As both oxidants and reductants may be transiently generated in the same reaction vessel, photoredox approaches may be used to develop reactions requiring both the donation and the reception of electrons at disparate points in the reaction mechanism. This approach stands in contrast to methods requiring stoichiometric chemical oxidants and reductants, which are often incompatible with each other, as well as to electrochemical approaches, which are not amenable to redox neutral transformations. Furthermore, single electron transfer events often provide access to radical ion intermediates having reactivity patterns fundamentally different from those of their ground electronic or excited states.14 Access to these intermediates using other means of activation is often challenging or requires conditions under which their unique reactivity cannot be productively harnessed. At the same time, photoredox catalysts such as Ru(bpy)32+ may also be employed to generate radicals for use in a diverse range of established radical chemistries. Photoredox reactions occur under extremely mild conditions, with most reactions proceeding at room temperature without the need for highly reactive radical initiators. The irradiation source is typically a commercial household light bulb, a significant advantage over the specialized equipment required for processes employing high energy ultraviolet (UV) light. Additionally, because organic molecules generally do not absorb visible light, there is little potential for deleterious side reactions that might arise from photoexcitation of the substrate itself. Finally, photoredox catalysts may be employed at very low loadings, with 1 mole or less being typical. This Review will highlight the early work on the use of transition metal complexes as photoredox catalysts to promote reactions of organic compounds (prior to 2008) as well as cover the surge of work that has appeared since 2008. We have for the most part grouped reactions according to whether the organic substrate undergoes reduction, oxidation, or a redox neutral reaction and throughout have sought to highlight the variety of reactive intermediates that may be accessed via this general reaction manifold.15 Studies on the use of transition metal complexes as visible light photocatalysts for organic synthesis have benefited tremendously from advances in the related fields of organic and semiconductor photocatalysis. Many organic molecules may function as visible light photocatalysts; analogous to metal complexes such as Ru(bpy)32+ organic dyes such as eosin Y, 9,10 dicyanoanthracene, and triphenylpyrylium salts absorb light in the visible region to give excited states capable of single electron transfer. These catalysts have been employed to achieve a vast range of bond forming reactions of broad utility in organic synthesis.16 Visible light photocatalysis has also been carried out with heterogeneous semiconductors such as mesoporous carbon nitride17 and various metal oxides and sulfides.18 These approaches are often complementary to photoredox catalysis with transition metal polypyridyl complexes, and we have referred to work in these areas when it is similar to the chemistry under discussion. However, an in depth discussion of the extensive literature in these fields is outside the scope of this Review, and readers are directed to existing reviews on these topics.16 18", "author_names": [ "Christopher K Prier", "Danica A Rankic", "David W C MacMillan" ], "corpus_id": 206897978, "doc_id": "206897978", "n_citations": 4145, "n_key_citations": 3, "score": 0, "title": "Visible light photoredox catalysis with transition metal complexes: applications in organic synthesis.", "venue": "Chemical reviews", "year": 2013 }, { "abstract": "This Review is aimed at synthetic organic chemists who may be familiar with organometallic catalysis but have no experience with biocatalysis, and seeks to provide an answer to the perennial question: if it is so attractive, why wasn't it extensively used in the past? The development of biocatalysis in industrial organic synthesis is traced from the middle of the last century. Advances in molecular biology in the last two decades, in particular genome sequencing, gene synthesis and directed evolution of proteins, have enabled remarkable improvements in scope and substantially reduced biocatalyst development times and cost contributions. Additionally, improvements in biocatalyst recovery and reuse have been facilitated by developments in enzyme immobilization technologies. Biocatalysis has become eminently competitive with chemocatalysis and the biocatalytic production of important pharmaceutical intermediates, such as enantiopure alcohols and amines, has become mainstream organic synthesis. The synthetic space of biocatalysis has significantly expanded and is currently being extended even further to include new to nature biocatalytic reactions.", "author_names": [ "Roger Arthur Sheldon", "Dean Brady" ], "corpus_id": 91189449, "doc_id": "91189449", "n_citations": 111, "n_key_citations": 0, "score": 1, "title": "Broadening the Scope of Biocatalysis in Sustainable Organic Synthesis.", "venue": "ChemSusChem", "year": 2019 }, { "abstract": "Nature is capable of storing solar energy in chemical bonds via photosynthesis through a series of C C, C O and C N bond forming reactions starting from CO2 and light. Direct capture of solar energy for organic synthesis is a promising approach. Lead (Pb) halide perovskite solar cells reach 24.2% power conversion efficiency, rendering perovskite a unique type material for solar energy capture. We argue that photophysical properties of perovskites already proved for photovoltaics, also should be of interest in photoredox organic synthesis. Because the key aspects of these two applications are both relying on charge separation and transfer. Here we demonstrated that perovskites nanocrystals are exceptional candidates as photocatalysts for fundamental organic reactions, for example C C, C N and C O bond formations. Stability of CsPbBr3 in organic solvents and ease of tuning their bandedges garner perovskite a wider scope of organic substrate activations. Our low cost, easy to process, highly efficient, air tolerant and bandedge tunable perovskites may bring new breakthrough in organic chemistry.While photoredox catalysis provides organic chemistry new avenues for chemical reactions, typical photocatalysts require expensive noble metals and show modest stabilities. Here, authors examine lead halide perovskites nanocrystals as stable and tunable photoredox catalysts for organic synthesis.", "author_names": [ "Xiaolin Zhu", "Yixiong Lin", "Jovan San Martin", "Yue Sun", "Dian Zhu", "Yong Yan" ], "corpus_id": 195737578, "doc_id": "195737578", "n_citations": 107, "n_key_citations": 0, "score": 0, "title": "Lead halide perovskites for photocatalytic organic synthesis", "venue": "Nature Communications", "year": 2019 }, { "abstract": "Clear directions for a robotic platform The chemistry literature contains more than a century's worth of instructions for making molecules, all written by and for humans. Steiner et al. developed an autonomous compiler and robotic laboratory platform to synthesize organic compounds on the basis of standardized methods descriptions (see the Perspective by Milo) The platform comprises conventional equipment such as round bottom flasks, separatory funnels, and a rotary evaporator to maximize its compatibility with extant literature. The authors showcase the system with short syntheses of three common pharmaceuticals that proceeded comparably to manual synthesis. Science, this issue p. eaav2211; see also p. 122 A compiler directs a robotic platform to conduct short organic syntheses using standard protocols and laboratory equipment. INTRODUCTION Outside of a few well defined areas such as polypeptide and oligonucleotide chemistry, the automation of chemical synthesis has been limited to large scale bespoke industrial processes, with laboratory scale and discovery scale synthesis remaining predominantly a manual process. These areas are generally defined by the ability to synthesize complex molecules by the successive iteration of similar sets of reactions, allowing the synthesis of products by the automation of a relatively small palette of standardized reactions. Recent advances in areas such as flow chemistry, oligosaccharide synthesis, and iterative cross coupling are expanding the number of compounds synthesized by automated methods. However, there is no universal and interoperable standard that allows the automation of chemical synthesis more generally. RATIONALE We developed a standard approach that mirrors how the bench chemist works and how the bulk of the open literature is reported, with the round bottomed flask as the primary reactor. We assembled a relatively small array of equipment to accomplish a wide variety of different syntheses, and our abstraction of chemical synthesis encompasses the four key stages of synthetic protocols: reaction, workup, isolation, and purification. Further, taking note of the incomplete way chemical procedures are reported, we hypothesized that a standardized format for reporting a chemical synthesis procedure, coupled with an abstraction and formalism linking the synthesis to physical operations of an automated robotic platform, would yield a universal approach to a chemical programming language. We call this architecture and abstraction the Chemputer. RESULTS For the Chemputer system to accomplish the automated synthesis of target molecules, we developed a program, the Chempiler, to produce specific, low level instructions for modular hardware of our laboratory scale synthesis robot. The Chempiler takes information about the physical connectivity and composition of the automated platform, in the form of a graph using the open source GraphML format, and combines it with a hardware independent scripting language [chemical assembly (ChASM) language] which provides instructions for the machine operations of the automated platform. The Chempiler software allows the ChASM code for a protocol to be run without editing on any unique hardware platform that has the correct modules for the synthesis. Formalization of a written synthetic scheme by using a chemical descriptive language (XDL) eliminates the ambiguous interpretation of the synthesis procedures. This XDL scheme is then translated into the ChASM file for a particular protocol. An automated robotic platform was developed, consisting of a fluidic backbone connected to a series of modules capable of performing the operations necessary to complete a synthetic sequence. The backbone allows the efficient transfer of the required chemicals into and out of any module of the platform, as well as the flushing and washing of the entire system during multistep procedures in which the modules are reused multiple times. The modules developed for the system consist of a reaction flask, a jacketed filtration setup capable of being heated or cooled, an automated liquid liquid separation module, and a solvent evaporation module. With these four modules, it was possible to automate the synthesis of the pharmaceutical compounds diphenhydramine hydrochloride, rufinamide, and sildenafil without human interaction, in yields comparable to those achieved in traditional manual syntheses. CONCLUSION The Chemputer allows for an abstraction of chemical synthesis, when coupled with a high level chemical programming language, to be compiled by our Chempiler into a low level code that can run on a modular standard robotic platform for organic synthesis. The software and modular hardware standards permit synthetic protocols to be captured as digital code. This code can be published, versioned, and transferred flexibly between physical platforms with no modification. We validated this concept by the automated synthesis of three pharmaceutical compounds. This represents a step toward the automation of bench scale chemistry more generally and establishes a standard aiming at increasing reproducibility, safety, and collaboration. Abstraction of organic synthesis to the Chemputer software and hardware standards. The Chemputer system can perform multistep organic synthesis protocols on the bench by using a modular system with hardware and software standards. The synthesis of complex organic compounds is largely a manual process that is often incompletely documented. To address these shortcomings, we developed an abstraction that maps commonly reported methodological instructions into discrete steps amenable to automation. These unit operations were implemented in a modular robotic platform by using a chemical programming language that formalizes and controls the assembly of the molecules. We validated the concept by directing the automated system to synthesize three pharmaceutical compounds, diphenhydramine hydrochloride, rufinamide, and sildenafil, without any human intervention. Yields and purities of products and intermediates were comparable to or better than those achieved manually. The syntheses are captured as digital code that can be published, versioned, and transferred flexibly between platforms with no modification, thereby greatly enhancing reproducibility and reliable access to complex molecules.", "author_names": [ "Sebastian Steiner", "Jakob Wolf", "Stefan Glatzel", "Anna Andreou", "Jaroslaw M Granda", "Graham Keenan", "Trevor Hinkley", "Gerardo Aragon-Camarasa", "Philip J Kitson", "Davide Angelone", "Leroy Cronin" ], "corpus_id": 54166255, "doc_id": "54166255", "n_citations": 145, "n_key_citations": 2, "score": 0, "title": "Organic synthesis in a modular robotic system driven by a chemical programming language", "venue": "Science", "year": 2019 }, { "abstract": "AbstractDespite decades of ground breaking research in academia, organic synthesis is still a rate limiting factor in drug discovery projects. Here we present some current challenges in synthetic organic chemistry from the perspective of the pharmaceutical industry and highlight problematic steps that, if overcome, would find extensive application in the discovery of transformational medicines. Significant synthesis challenges arise from the fact that drug molecules typically contain amines and N heterocycles, as well as unprotected polar groups. There is also a need for new reactions that enable non traditional disconnections, more C H bond activation and late stage functionalization, as well as stereoselectively substituted aliphatic heterocyclic ring synthesis, C X or C C bond formation. We also emphasize that syntheses compatible with biomacromolecules will find increasing use, while new technologies such as machine assisted approaches and artificial intelligence for synthesis planning have the potential to dramatically accelerate the drug discovery process. We believe that increasing collaboration between academic and industrial chemists is crucial to address the challenges outlined here.Organic synthesis is a rate limiting factor in drug discovery, so the pharmaceutical industry heavily relies on academic research. This Perspective highlights some of the most pressing challenges to be overcome from the industrial viewpoint such as the development of reactions tolerating specific functionalities and encourages stronger industry academia relationships. Credit: Pills image: Profimedia.CZ a.s. Alamy Stock Photo; Factory image: Diana Johanna Velasquez Alamy Stock Vector; Graduate hat: Michael Burrell Alamy Stock Photo; Conical flask: Astex.", "author_names": [ "David C Blakemore", "Luis Castro", "Ian Churcher", "David Charles Rees", "Andrew William Thomas", "David M Wilson", "Anthony Wood" ], "corpus_id": 4189727, "doc_id": "4189727", "n_citations": 417, "n_key_citations": 2, "score": 0, "title": "Organic synthesis provides opportunities to transform drug discovery", "venue": "Nature Chemistry", "year": 2018 }, { "abstract": "Visible light photocatalysis has evolved over the last decade into a widely used method in organic synthesis. Photocatalytic variants have been reported for many important transformations, such as cross coupling reactions, a amino functionalizations, cycloadditions, ATRA reactions, or fluorinations. To help chemists select photocatalytic methods for their synthesis, we compare in this Review classical and photocatalytic procedures for selected classes of reactions and highlight their advantages and limitations. In many cases, the photocatalytic reactions proceed under milder reaction conditions, typically at room temperature, and stoichiometric reagents are replaced by simple oxidants or reductants, such as air, oxygen, or amines. Does visible light photocatalysis make a difference in organic synthesis? The prospect of shuttling electrons back and forth to substrates and intermediates or to selectively transfer energy through a visible light absorbing photocatalyst holds the promise to improve current procedures in radical chemistry and to open up new avenues by accessing reactive species hitherto unknown, especially by merging photocatalysis with organo or metal catalysis.", "author_names": [ "Leyre Marzo", "Santosh K Pagire", "Oliver Reiser", "Burkhard Konig" ], "corpus_id": 3396984, "doc_id": "3396984", "n_citations": 630, "n_key_citations": 0, "score": 0, "title": "Visible Light Photocatalysis: Does It Make a Difference in Organic Synthesis?", "venue": "Angewandte Chemie", "year": 2018 }, { "abstract": "Abstract The direct synthetic organic use of electricity is currently experiencing a renaissance. More synthetically oriented laboratories working in this area are exploiting both novel and more traditional concepts, paving the way to broader applications of this niche technology. As only electrons serve as reagents, the generation of reagent waste is efficiently avoided. Moreover, stoichiometric reagents can be regenerated and allow a transformation to be conducted in an electrocatalytic fashion. However, the application of electroorganic transformations is more than minimizing the waste footprint, it rather gives rise to inherently safe processes, reduces the number of steps of many syntheses, allows for milder reaction conditions, provides alternative means to access desired structural entities, and creates intellectual property (IP) space. When the electricity originates from renewable resources, this surplus might be directly employed as a terminal oxidizing or reducing agent, providing an ultra sustainable and therefore highly attractive technique. This Review surveys recent developments in electrochemical synthesis that will influence the future of this area.", "author_names": [ "Anton Wiebe", "Tile Gieshoff", "Sabine Moehle", "Eduardo Rodrigo", "Michael Zirbes", "Siegfried R Waldvogel" ], "corpus_id": 3724646, "doc_id": "3724646", "n_citations": 450, "n_key_citations": 0, "score": 0, "title": "Electrifying Organic Synthesis", "venue": "Angewandte Chemie", "year": 2018 }, { "abstract": "Continuous flow photochemistry in microreactors receives a lot of attention from researchers in academia and industry as this technology provides reduced reaction times, higher selectivities, straightforward scalability, and the possibility to safely use hazardous intermediates and gaseous reactants. In this review, an up to date overview is given of photochemical transformations in continuous flow reactors, including applications in organic synthesis, material science, and water treatment. In addition, the advantages of continuous flow photochemistry are pointed out and a thorough comparison with batch processing is presented.", "author_names": [ "Dario Cambie", "Cecilia Bottecchia", "Natan J W Straathof", "Volker Hessel", "Timothy Noel" ], "corpus_id": 206535785, "doc_id": "206535785", "n_citations": 692, "n_key_citations": 2, "score": 0, "title": "Applications of Continuous Flow Photochemistry in Organic Synthesis, Material Science, and Water Treatment.", "venue": "Chemical reviews", "year": 2016 }, { "abstract": "Photocatalysis, the use of light to promote organic transformations, is a field of catalysis that has received limited attention despite existing for over 100 years. With the revolution of photoredox catalysis in 2008, the rebirth or awakening of the field of photoorganocatalysis has brought new ideas and reactions to organic synthesis. This review will focus on the sudden outburst of literature regarding the use of small organic molecules as photocatalysts after 2013. In particular, it will focus on acridinium salts, benzophenones, pyrylium salts, thioxanthone derivatives, phenylglyoxylic acid, BODIPYs, flavin derivatives, and classes of organic molecules as catalysts for the photocatalytic generation of C C and C X bonds.", "author_names": [ "Ioanna K Sideri", "Errika Voutyritsa", "Christoforos G Kokotos" ], "corpus_id": 47011586, "doc_id": "47011586", "n_citations": 87, "n_key_citations": 0, "score": 0, "title": "Photoorganocatalysis, small organic molecules and light in the service of organic synthesis: the awakening of a sleeping giant.", "venue": "Organic biomolecular chemistry", "year": 2018 }, { "abstract": "Ionic liquids (ILs) have now been acknowledged as reaction media for biotransformations. The first three examples were reported in this field in 2000, and since then, numerous applications have been reported for biocatalytic reactions using ILs. Two topics using ILs for enzymatic reactions have been reviewed from the standpoint of biocatalyst mediating organic synthesis; the first is \"Biocatalysis in Ionic Liquids\" which includes various types of biocatalytic reactions in ILs (section 2) (1) recent examples of lipase mediated reactions using ILs as reaction media for biodiesel oil production and for sugar ester production, (2) oxidase catalyzed reactions in ILs, (3) laccase catalyzed reactions, (4) peroxidase catalyzed reactions, (4) cytochrome mediated reactions, (5) microbe mediated hydrations, (6) protease catalyzed reactions, (8) whole cell mediated asymmetric reduction of ketones, (10) acylase catalyzed reactions, (11) glycosylation or cellulase mediated hydrolysis of polysaccharides, (12) hydroxynitrile lyase catalyzed reaction, (13) fluorinase or haloalkane dehydrogenase catalyzed reaction, (14) luciferase catalyzed reactions, and (15) biocatalytic promiscuity of enzymatic reactions for organic synthesis using ILs. The second is \"Enzymes Activated by Ionic Liquids for Organic Synthesis\" particularly describing the finding story of activation of lipases by the coating with a PEG substituted IL (section 3) The author's opinion toward \"Future Perspectives of Using ILs for Enzymatic Reactions\" has also been discussed in section 4.", "author_names": [ "Toshiyuki Itoh" ], "corpus_id": 206540123, "doc_id": "206540123", "n_citations": 169, "n_key_citations": 2, "score": 0, "title": "Ionic Liquids as Tool to Improve Enzymatic Organic Synthesis.", "venue": "Chemical reviews", "year": 2017 } ]

[ { "abstract": "In recent years, semiconductor photocatalytic process has shown a great potential as a low cost, environmental friendly and sustainable treatment technology to align with the \"zero\" waste scheme in the water/wastewater industry. The ability of this advanced oxidation technology has been widely demonstrated to remove persistent organic compounds and microorganisms in water. At present, the main technical barriers that impede its commercialisation remained on the post recovery of the catalyst particles after water treatment. This paper reviews the recent R&D progresses of engineered photocatalysts, photoreactor systems, and the process optimizations and modellings of the photooxidation processes for water treatment. A number of potential and commercial photocatalytic reactor configurations are discussed, in particular the photocatalytic membrane reactors. The effects of key photoreactor operation parameters and water quality on the photo process performances in terms of the mineralization and disinfection are assessed. For the first time, we describe how to utilize a multi variables optimization approach to determine the optimum operation parameters so as to enhance process performance and photooxidation efficiency. Both photomineralization and photo disinfection kinetics and their modellings associated with the photocatalytic water treatment process are detailed. A brief discussion on the life cycle assessment for retrofitting the photocatalytic technology as an alternative waste treatment process is presented. This paper will deliver a scientific and technical overview and useful information to scientists and engineers who work in this field.", "author_names": [ "Meng Nan Chong", "Bo Jin", "Christopher W K Chow", "Christopher P Saint" ], "corpus_id": 11490118, "doc_id": "11490118", "n_citations": 3562, "n_key_citations": 105, "score": 0, "title": "Recent developments in photocatalytic water treatment technology: a review.", "venue": "Water research", "year": 2010 }, { "abstract": "Among various water purification and recycling technologies, adsorption is a fast, inexpensive and universal method. The development of low cost adsorbents has led to the rapid growth of research interests in this field. The present protocol describes salient features of adsorption and details experimental methodologies for the development and characterization of low cost adsorbents, water treatment and recycling using adsorption technology including batch processes and column operations. The protocol describes the development of inexpensive adsorbents from waste materials, which takes only 1 2 days, and an adsorption process taking 15 120 min for the removal of pollutants. The applications of batch and column processes are discussed, along with suggestions to make this technology more popular and applicable.", "author_names": [ "Imran Ali", "V K Gupta" ], "corpus_id": 6436105, "doc_id": "6436105", "n_citations": 1017, "n_key_citations": 10, "score": 0, "title": "Advances in water treatment by adsorption technology", "venue": "Nature Protocols", "year": 2007 }, { "abstract": "Reverse osmosis membrane technology has developed over the past 40 years to a 44% share in world desalting production capacity, and an 80% share in the total number of desalination plants installed worldwide. The use of membrane desalination has increased as materials have improved and costs have decreased. Today, reverse osmosis membranes are the leading technology for new desalination installations, and they are applied to a variety of salt water resources using tailored pretreatment and membrane system design. Two distinct branches of reverse osmosis desalination have emerged: seawater reverse osmosis and brackish water reverse osmosis. Differences between the two water sources, including foulants, salinity, waste brine (concentrate) disposal options, and plant location, have created significant differences in process development, implementation, and key technical problems. Pretreatment options are similar for both types of reverse osmosis and depend on the specific components of the water source. Both brackish water and seawater reverse osmosis (RO) will continue to be used worldwide; new technology in energy recovery and renewable energy, as well as innovative plant design, will allow greater use of desalination for inland and rural communities, while providing more affordable water for large coastal cities. A wide variety of research and general information on RO desalination is available; however, a direct comparison of seawater and brackish water RO systems is necessary to highlight similarities and differences in process development. This article brings to light key parameters of an RO process and process modifications due to feed water characteristics.", "author_names": [ "Lauren F Greenlee", "Desmond F Lawler", "Benny D Freeman", "Benoit Marrot", "Philippe Moulin" ], "corpus_id": 26107135, "doc_id": "26107135", "n_citations": 2184, "n_key_citations": 75, "score": 0, "title": "Reverse osmosis desalination: water sources, technology, and today's challenges.", "venue": "Water research", "year": 2009 }, { "abstract": "One of the most pervasive problems afflicting people throughout the world is inadequate access to clean water and sanitation. Problems with water are expected to grow worse in the coming decades, with water scarcity occurring globally, even in regions currently considered water rich. Addressing these problems calls out for a tremendous amount of research to be conducted to identify robust new methods of purifying water at lower cost and with less energy, while at the same time minimizing the use of chemicals and impact on the environment. Here we highlight some of the science and technology being developed to improve the disinfection and decontamination of water, as well as efforts to increase water supplies through the safe re use of wastewater and efficient desalination of sea and brackish water.", "author_names": [ "Mark A Shannon", "Paul W Bohn", "Menachem Elimelech", "John G Georgiadis", "Benito J Marinas", "Anne M Mayes" ], "corpus_id": 4424103, "doc_id": "4424103", "n_citations": 5562, "n_key_citations": 65, "score": 1, "title": "Science and technology for water purification in the coming decades", "venue": "Nature", "year": 2008 }, { "abstract": "The global population is increasing and because of this, the world may experience great fresh water scarcity. Our water resources are limited and, hence, water treatment and recycling methods are the only alternatives for getting fresh water in the coming decades. Therefore, there is a great need for the development of a suitable, inexpensive and rapid wastewater treatment techniques and reuse or conservation methods in the present century. The different types of water treatment and recycling techniques have been discussed in terms of their basic principles, applications, costs, maintenance and suitability. Additionally, a systematic approach to water treatment and recycling involving their understanding, evaluation and selection parameters has been presented. A brief guideline for the selection of the appropriate technologies for specific applications has been evaluated. This review adds to the global discussions on water scarcity solutions.", "author_names": [ "Vinod K Gupta", "Imran Ali", "Tawfik A Saleh", "Arunima Nayak", "Shilpi Agarwal" ], "corpus_id": 95114694, "doc_id": "95114694", "n_citations": 1108, "n_key_citations": 22, "score": 0, "title": "Chemical treatment technologies for waste water recycling an overview", "venue": "", "year": 2012 }, { "abstract": "Morpholino phosphorodiamidate antisense oligonucleotides (MOs) and short interfering RNAs (siRNAs) are commonly used platforms to study gene function by sequence specific knockdown. Both technologies, however, can elicit undesirable off target effects. We have used several model genes to study these effects in detail in the zebrafish, Danio rerio. Using the zebrafish embryo as a template, correct and mistargeting effects are readily discernible through direct comparison of MO injected animals with well studied mutants. We show here indistinguishable off targeting effects for both maternal and zygotic mRNAs and for both translational and splice site targeting MOs. The major off targeting effect is mediated through p53 activation, as detected through the transferase mediated dUTP nick end labeling assay, acridine orange, and p21 transcriptional activation assays. Concurrent knockdown of p53 specifically ameliorates the cell death induced by MO off targeting. Importantly, reversal of p53 dependent cell death by p53 knockdown does not affect specific loss of gene function, such as the cell death caused by loss of function of chordin. Interestingly, quantitative reverse transcriptase PCR, microarrays and whole mount in situ hybridization assays show that MO off targeting effects are accompanied by diagnostic transcription of an N terminal truncated p53 isoform that uses a recently recognized internal p53 promoter. We show here that MO off targeting results in induction of a p53 dependent cell death pathway. p53 activation has also recently been shown to be an unspecified off target effect of siRNAs. Both commonly used knockdown technologies can thus induce secondary but sequence specific p53 activation. p53 inhibition could potentially be applicable to other systems to suppress off target effects caused by other knockdown technologies.", "author_names": [ "Mara E Robu", "Jon D Larson", "Aidas Nasevicius", "Soraya Beiraghi", "Charles Brenner", "Steven Arthur Farber", "Stephen C Ekker" ], "corpus_id": 9914091, "doc_id": "9914091", "n_citations": 1019, "n_key_citations": 101, "score": 0, "title": "p53 Activation by Knockdown Technologies", "venue": "PLoS genetics", "year": 2007 }, { "abstract": "1. Introduction 2. Theoretical foundations 3. Propagation and focusing of optical fields 4. Spatial resolution and position accuracy 5. Nanoscale optical microscopy 6. Near field optical probes 7. Probe sample distance control 8. Light emission and optical interaction in nanoscale environments 9. Quantum emitters 10. Dipole emission near planar interfaces 11. Photonic crystals and resonators 12. Surface plasmons 13. Forces in confined fields 14. Fluctuation induced phenomena 15. Theoretical methods in nano optics Appendices Index.", "author_names": [ "Lukas Novotny", "Bert Hecht" ], "corpus_id": 29065627, "doc_id": "29065627", "n_citations": 3553, "n_key_citations": 332, "score": 0, "title": "Principles of nano optics", "venue": "", "year": 2006 }, { "abstract": "The elimination of selected pharmaceuticals (bezafibrate, clofibric acid, carbamazepine, diclofenac) during drinking water treatment processes was investigated at lab and pilot scale and in real waterworks. No significant removal of pharmaceuticals was observed in batch experiments with sand under natural aerobic and anoxic conditions, thus indicating low sorption properties and high persistence with nonadapted microorganisms. These results were underscored by the presence of carbamazepine in bank filtrated water with anaerobic conditions in a waterworks area. Flocculation using iron(III) chloride in lab scale experiments (Jar test) and investigations in waterworks exhibited no significant elimination of the selected target pharmaceuticals. However, ozonation was in some cases very effective in eliminating these polar compounds. In lab scale experiments, 0.5 mg/L ozone was shown to reduce the concentrations of diclofenac and carbamazepine by more than 90% while bezafibrate was eliminated by 50% with a 1.5 mg/L ozone dose. Clofibric acid was stable even at 3 mg/L ozone. Under waterworks conditions, similar removal efficiencies were observed. In addition to ozonation, filtration with granular activated carbon (GAC) was very effective in removing pharmaceuticals. Except for clofibric acid, GAC in pilot scale experiments and waterworks provided a major elimination of the pharmaceuticals under investigation.", "author_names": [ "Thomas A Ternes", "Martin Meisenheimer", "Derek McDowell", "Frank Sacher", "H J Brauch", "Brigitte Haist-Gulde", "Gudrun Preuss", "U Wilme", "Ninette Zulei-Seibert" ], "corpus_id": 9337900, "doc_id": "9337900", "n_citations": 1129, "n_key_citations": 46, "score": 0, "title": "Removal of pharmaceuticals during drinking water treatment.", "venue": "Environmental science technology", "year": 2002 }, { "abstract": "Abstract Although micro and nano bubble technology has been attracting attention in many fields, the state of water after the introduction of those bubbles is still not clear. In this study, the existence and stabilization of nano bubbles after the generation of bubbles were investigated. The presence of nano sized particles was detected through dynamic light scattering for days, when pure oxygen was used to generate the bubbles, and for less than 1 h, in the case of air bubbles. NMR spin lattice relaxation time increased with the introduction of micro and nano bubbles in manganese ions solution, indicating the presence of a gas liquid interface which adsorbed the manganese ions. Furthermore, the zeta potential measured in the water after the introduction of oxygen micro and nano bubbles was in the range from 45 mV to 34 mV and from 20 mV to 17 mV in water bubbled with air, indicating the presence of stable electrically charged particles. This study suggested a strong possibility of the existence of nano bubbles in water for a long time. The stability of nano bubbles is supported by the electrically charged liquid gas interface, which creates repulsion forces that prevent the bubble coalescence, and by the high dissolved gas concentration in the water, which keeps a small concentration gradient between the interface and the bulk liquid.", "author_names": [ "Fernanda Yumi Ushikubo", "T Furukawa", "Ryo Nakagawa", "Masato Enari", "Yoshio Makino", "Yoshinori Kawagoe", "Takeo Shiina", "Seiichi Oshita" ], "corpus_id": 97545746, "doc_id": "97545746", "n_citations": 245, "n_key_citations": 11, "score": 0, "title": "Evidence of the existence and the stability of nano bubbles in water", "venue": "", "year": 2010 }, { "abstract": "Spray drying technology is widely known and used to transform liquids (solutions, emulsions, suspension, slurries, pastes or even melts) into solid powders. Its main applications are found in the food, chemical and materials industries to enhance ingredient conservation, particle properties, powder handling and storage etc. However, spray drying can also be used for specific applications in the formulation of pharmaceuticals for drug delivery (e.g. particles for pulmonary delivery) Buchi is a reference in the development of spray drying technology, notably for laboratory scale devices. This study presents the Nano Spray Dryer B 90, a revolutionary new sprayer developed by Buchi, use of which can lower the size of the produced dried particles by an order of magnitude attaining submicron sizes. In this paper, results are presented with a panel of five representative polymeric wall materials (arabic gum, whey protein, polyvinyl alcohol, modified starch, and maltodextrin) and the potentials to encapsulate nano emulsions, or to formulate nano crystals (e.g. from furosemide) are also shown.", "author_names": [ "Xiang Li", "Nicolas Anton", "Cordin Arpagaus", "Fabrice Belleteix", "Thierry F Vandamme" ], "corpus_id": 45205199, "doc_id": "45205199", "n_citations": 287, "n_key_citations": 15, "score": 0, "title": "Nanoparticles by spray drying using innovative new technology: the Buchi nano spray dryer B 90.", "venue": "Journal of controlled release official journal of the Controlled Release Society", "year": 2010 } ]

[ { "abstract": "This review describes a new paradigm of electronics based on the spin degree of freedom of the electron. Either adding the spin degree of freedom to conventional charge based electronic devices or using the spin alone has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices. To successfully incorporate spins into existing semiconductor technology, one has to resolve technical issues such as efficient injection, transport, control and manipulation, and detection of spin polarization as well as spin polarized currents. Recent advances in new materials engineering hold the promise of realizing spintronic devices in the near future. We review the current state of the spin based devices, efforts in new materials fabrication, issues in spin transport, and optical spin manipulation.", "author_names": [ "Stuart A Wolf", "David D Awschalom", "Robert A Buhrman", "J M Daughton", "Stephan von Molnar", "Michael L Roukes", "Almadena Yu Chtchelkanova", "Daryl M Treger" ], "corpus_id": 14010432, "doc_id": "14010432", "n_citations": 8448, "n_key_citations": 39, "score": 1, "title": "Spintronics: A Spin Based Electronics Vision for the Future", "venue": "Science", "year": 2001 }, { "abstract": "", "author_names": [ "Almadena Yu Chtchelkanova", "Stuart A Wolf", "Daryl M Treger" ], "corpus_id": 138390698, "doc_id": "138390698", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Spintronics Spin Based Electronics", "venue": "", "year": 2002 }, { "abstract": "Abstract Fundamental limitation of current charge based electronics technology is imminent as the technology progresses ever faster than before. Spin based electronics or spintronics, which is a new field of electronics utilizing additional spin degree of freedom, is one of many technology options to fundamentally solve the limitation of current electronics. In this paper, current programs and accomplishments of spintronics research in Korea are briefly reviewed. In particular, research accomplishments achieved at KIST are described.", "author_names": [ "S H Lim", "Suk Hee Han", "K H Shin" ], "corpus_id": 123138416, "doc_id": "123138416", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Spin based electronics and its activities and progress", "venue": "", "year": 2006 }, { "abstract": "", "author_names": [ "William A Goddard", "Donald W Brenner", "Sergey Edward Lyshevski", "G J Iafrate" ], "corpus_id": 223185226, "doc_id": "223185226", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Spintronics Spin Based Electronics", "venue": "", "year": 2002 }, { "abstract": "Organic semiconductors are studied intensively for applications in electronics and optics, and even spin based information technology, or spintronics. Fundamental quantities in spintronics are the population relaxation time (T1) and the phase memory time (T2) T1 measures the lifetime of a classical bit, in this case embodied by a spin oriented either parallel or antiparallel to an external magnetic field, and T2 measures the corresponding lifetime of a quantum bit, encoded in the phase of the quantum state. Here we establish that these times are surprisingly long for a common, low cost and chemically modifiable organic semiconductor, the blue pigment copper phthalocyanine, in easily processed thin film form of the type used for device fabrication. At 5 K, a temperature reachable using inexpensive closed cycle refrigerators, T1 and T2 are respectively 59 ms and 2.6 ms, and at 80 K, which is just above the boiling point of liquid nitrogen, they are respectively 10 ms and 1 ms, demonstrating that the performance of thin film copper phthalocyanine is superior to that of single molecule magnets over the same temperature range. T2 is more than two orders of magnitude greater than the duration of the spin manipulation pulses, which suggests that copper phthalocyanine holds promise for quantum information processing, and the long T1 indicates possibilities for medium term storage of classical bits in all organic devices on plastic substrates.", "author_names": [ "Marc Warner", "Salahud Din", "Igor S Tupitsyn", "Gavin W Morley", "A M Stoneham", "Jules A Gardener", "Zhenlin Wu", "Andrew J Fisher", "Sandrine Heutz", "Christopher W M Kay", "Gabriel Aeppli" ], "corpus_id": 4467253, "doc_id": "4467253", "n_citations": 187, "n_key_citations": 3, "score": 0, "title": "Potential for spin based information processing in a thin film molecular semiconductor", "venue": "Nature", "year": 2013 }, { "abstract": "In very near future human blood will be streaming with tiny nanorobots to get exact information about the infected cells or as intelligent drug delivery system and transmit the information to wireless cloud. Accordingly, low power and low dimensional electronics technology needs to be incorporated in a single agenda to show the path for development of these types of robots. Hence, the idea is to build low power, low dimensional nano robotic system which can be achieved by new generation ULSI hardware implementation. As an attempt towards this, here we present a straintronics based nano robotic system and its ULSI architecture. Straintronics or strain based spin electronics is an emerging field of IC fabrication technology for modern and future electronics. In straintronics data manipulate, control and store with spin degree of freedom. Electron spin instead of electron charge carries information in these devices. Hence, it requires very low power to operate and also the device can generate its own power from any stress upon it. This aspect offers opportunities for development of new generation of nano robotic devices with spin based electronics.", "author_names": [ "Sampreet Sarkar", "Syed Intekhab Alam", "Varun Ravindran", "Arpan Banerjee", "Arghya Debnath", "Ankush Ghosh" ], "corpus_id": 90263626, "doc_id": "90263626", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Spintronics based Systems for AI Nano Robots", "venue": "2018 International Conference on Computing, Power and Communication Technologies (GUCON)", "year": 2018 }, { "abstract": "Recent results in magnonics a topical and rapidly developing branch of spintronics and magnetoelectronics are presented. The paper describes measurement techniques and theoretical approaches used to explore physical processes associated with the spin wave propagation in complex nano and micro dimensional magnetic structures. The results of the application of magnetic structures in signal processing and transmission systems are discussed. In particular, results on spin wave propagation in distributed magnetic periodic structures, lumped systems, coupled waveguide structures, and controllable magnonic structures are considered. Specific examples of circuitry based on magnonic structures are discussed, and possibilities for further developing this circuitry are explored.", "author_names": [ "Sergey Nikitov", "D V Kalyabin", "Ivan Lisenkov", "Andrei Slavin", "Yu N Barabanenkov", "Sergey Osokin", "Alexandr V Sadovnikov", "E N Beginin", "Mariya A Morozova", "Y Filimonov", "Y V Khivintsev", "S L Vysotsky", "V K Sakharov", "E S Pavlov" ], "corpus_id": 123749702, "doc_id": "123749702", "n_citations": 114, "n_key_citations": 0, "score": 0, "title": "Magnonics: a new research area in spintronics and spin wave electronics", "venue": "", "year": 2015 }, { "abstract": "Advancement in molecular electronics opens up another new domain with a new possibility of realizing its spin polarized version, which is called molecular spintronics. This novel domain has a range of applications such as high capacity storage devices and quantum computers. Several contemporary researchers have considered porphyrin molecules and their derivatives as potential candidates for molecular devices. Herein, using the first principles calculations, we propose a porphyrin nanoribbon based system for spin filtering applications. Such a system shows robust half metallicity and also exhibits itinerant magnetism. Our calculated spin transport properties exhibit that our device can give 100% spin polarizing efficiency, which is very promising for next generation spin filtering applications.", "author_names": [ "Gargee Bhattacharyya", "Rameshwar L Kumawat", "Biswarup Pathak" ], "corpus_id": 220501511, "doc_id": "220501511", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Porphyrin nanoribbon based spin filtering devices.", "venue": "Physical chemistry chemical physics PCCP", "year": 2020 }, { "abstract": "Spin based electronics, or spintronics, seeks to utilize the electron degree of freedom in order to perform logic, computation, or information storage. Proximity based interactions between nearby systems (i.e. films, adsorbates, molecules) and candidate spintronic materials (i.e. GaAs, graphene) could lead to the realization of novel phenomena. Such effects, which rely on atomic orbital overlap, require highly controlled surfaces and interfaces which can be achieved using molecular beam epitaxy (MBE) Here, this dissertation examines the feasibility of integrating high quality single crystal ferromagnetic insulators with oxide interfaces, the semiconductor GaAs, and graphene. Graphene, a single atomic layer of sp 2 bonded carbon with conducting &pi orbitals that extend out of the plane, is highly surface sensitive and can be considered an ideal material for investigating novel spin based proximity related behavior. In particular, the interactions of functional oxides or adsorbates with graphene could lead to induced exchange splitting, magnetism, and spin orbit coupling. High quality crystalline deposition of the ferromagnetic insulator EuO is investigated with the primary focus of realizing high quality abrupt interfaces between the functional oxide and the spintronic material of choice. In this dissertation, stiochiometric EuO films are investigated on a wide variety of substrates including the spintronic relavent materials GaAs, 2 D planes of TiO2, and sp 2 bonded carbon. The integration of EuO on these materials is a key advance towards experimental observation of the exchange proximity effect.The atomic scale control over deposition provided by MBE allows for the investigation of submonolayer adsorbates (adatoms) and their interactions with graphene. In order to understand the effect of the adsorbates on spin based properties and phenomena, we have performed systematic in situ deposition of adatoms onto graphene non local spin valves. Atomic hydrogen induces magnetic moments in graphene that couple via exchange to the injected spin current. This coupling results in an exchange field which causes the spins to precess rapidly with an effectively enhanced electron g factor. These results demonstrate the power of molecular beam epitaxy in realizing novel graphene properties and functionality through careful control over the key interfaces and proximity materials.", "author_names": [ "Adrian G Swartz" ], "corpus_id": 137320435, "doc_id": "137320435", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Investigation of Spin Based Phenomena in Candidate Spintronic Materials by Molecular Beam Epitaxy", "venue": "", "year": 2013 }, { "abstract": "The electronic device industry is an age old industry. Several new electronic ICs evolved day by day with more and more components being cramped into smaller and smaller spaces. Presently, advanced VLSI and ULSI devices are made commercially available to the consumers. On the other hand, the micro electronics industry suffers from physical limitation as well as from technological limitation. Thereby, the search for new device principle cannot be avoided. In this regard Spintronics technology is vividly significant as it employs spin degree of freedom in quantum dot. Since the last decade Spintronics ushered numerous scope in device vicinity. Even though the hands of researchers are tied as there is no simulator for simulating Spintronics circuits and spin based logic devices. The authors now propose a MATLAB based tool which can be incorporated in SIMULINK for simulation of single spin logic devices. Here, GUI based approach is made to create spin environment to design dynamic part of simulation.", "author_names": [ "Jayanta Gope", "B Kar", "S Chowdhury Koly", "R Shome", "Sanjay Bhadra", "Anirban Bhattacharyya", "R Banerjee" ], "corpus_id": 3054383, "doc_id": "3054383", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "MATLAB GUI based simulation framework for spintronics", "venue": "2017 IEEE 8th Annual Ubiquitous Computing, Electronics and Mobile Communication Conference (UEMCON)", "year": 2017 } ]

[ { "abstract": "Abstract The modelling and simulation of low dimensional nanoelectronic devices is important, because the semiconductor industry has scaled transistors down to the sub 10 n m regime. The top of the barrier (ToB) transistor model has been developed and used to model transistors that are composed of various semiconducting materials. In this paper, a brief overview of the ToB transistor model is presented. The main objective of this paper is to provide a focused review on the device modelling milestones that have been achieved using the ToB transistor model. The accuracy of a few of these models is assessed by computing the normalised root mean square deviation. The ToB transistor model is widely used for computational studies on low dimensional field effect transistors with various channel materials, such as ultra thin bodies, two dimensional materials and one dimensional materials. The ToB transistor model is also useful for extensive research in circuit level simulations. In summary, this nanoscale model helps researchers to identify and evaluate the potential nanomaterials for future nanoelectronic applications.", "author_names": [ "Mu Wen Chuan", "Kien Liong Wong", "Afiq Hamzah", "Shahrizal Rusli", "Nurul Ezaila Alias", "Cheng Siong Lim", "Michael L P Tan" ], "corpus_id": 213705250, "doc_id": "213705250", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "A review of the top of the barrier nanotransistor models for semiconductor nanomaterials", "venue": "", "year": 2020 }, { "abstract": "In this study, we will compare the study done by different researchers on the semiconductor II VI group material by using different models including DMR (Diffusivity Mobility Ratio) We will check out the DMR and other model parameters used to compare the performance of semiconductor II VI group material. The basic formulation and the study of these models will help us to understand the basic properties of the nanomaterials studied so far. Keywords: DMR, Einstein relation, models, nanomaterial, semiconductor material group II VI", "author_names": [ "Rahul Jain", "Kh Gopal Krishna Singh" ], "corpus_id": 127554516, "doc_id": "127554516", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Comparative study of models for II VI group semiconductor nanomaterials using DMR", "venue": "", "year": 2018 }, { "abstract": "As synthesized colloidal indium nitride (InN) nanocrystals are degenerately doped with carrier densities large enough to lead to strong localized surface plasmon resonances (LSPR) in the infrared. Intriguingly, the LSPR energy is almost independent of carrier density, which premises that simple classical models that are often used to describe metallic systems inadequately describe the plasmonic response of InN nanoparticles. Here, an oxidative titration approach is used to directly quantify carrier densities in colloidal InN nanocrystals, eliminating the need to rely on any specific model. A size independent carrier density value of (7.4 0.4) x 1020 cm 3 is obtained for diameters varying between 4 and 9 nm, corresponding to about 30 to 300 electrons per nanocrystal, depending on size. Upon oxidation with nitrosonium salts, the carrier density in InN nanocrystals can be reduced to (3.9 0.3) x 1020 cm 3, also independent of size. The unusual plasmonic signatures of colloidal InN nanocrystals are shown t.", "author_names": [ "Zhihui Liu", "Remi Beaulac" ], "corpus_id": 104018338, "doc_id": "104018338", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Nature of the Infrared Transition of Colloidal Indium Nitride Nanocrystals: Nonparabolicity Effects on the Plasmonic Behavior of Doped Semiconductor Nanomaterials", "venue": "", "year": 2017 }, { "abstract": "Nanotechnology and engineered nanomaterials (ENM) empower existing technologies. One of the great examples are III V semiconductor nanowires (NW) which have a broad application range. The occupational safety and hazard organizations draw attention to ENM, as their physical and chemical characteristics differ from the ones of bulk materials. Additionally, the NW high aspect ratio geometry is of great concern, since it resembles the morphology of asbestos. Moreover, due to their small size, ENM materials are hard to detect and identify using conventional methods. During ENM technology development and large scale production, the highest risk of human exposure is via inhalation. Therefore, we need to study how NW affect lung tissue using experimental exposure models. The work in this thesis aimed at filling the knowledge gap in ENM detection and identification, as well as understanding III V semiconductor NW effects in in vitro and in vitro models.We have used enhanced darkfield microscopy hyperspectral imaging method to detect and identify ceria nanoparticles in three differently prepared samples, and compared different combinations of data analysis methods. The remaining part of the thesis was devoted to the study of the III V semiconductor NW effects on cells and tissue in vitro and in vivo. We have exposed two types of cell cultures (primary human lung (SAE) and human lung adenocarcinoma cell line (A549) to gallium phosphide (GaP) NW. We observed that both type of cells are capable to engulf NW after 2 days, and that NW do not have any effect on the SAE and A549 cell morphology after 7 and 5 days, respectively. The NW concentrations used in this work are not toxic to A549 cells, since we did not see a change in cell mobility, viability or changes in ROS levels. After inhibiting specific endocytosis pathways in A549 cells, we showed that NW are actively taken up via phagocytosis and/or macropinocytosis.Additionally, we have performed in vivo mice exposure to GaP NW via intratracheal instillation. We have observed that NW induce an inflammation and allergic reaction of similar levels as the ones observed after exposure to carcinogenic multiwall carbon nanotubes. Additionally, we show that NW are capable to cross tissue barriers and reach distant organs after 28 days, however without introducing changes to the organ tissues. Lastly, we have performed a pilot study, where we investigated the effect of NW photodiodes on A549 cells. We observed that the presence of light inhibits cell proliferation. Furthermore, we show that the chemical make up of the photodiodes is important, since some photodiodes dissolve in water based cell culturing media and release toxic compounds. (Less)", "author_names": [ "Laura Abariute" ], "corpus_id": 104443633, "doc_id": "104443633", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Engineered nanomaterials in in vivo and in vitro models", "venue": "", "year": 2018 }, { "abstract": "In designing and optimizing new generation nanomaterials and related quantum devices, dissipation versus decoherence phenomena are often accounted for via local scattering models, such as relaxation time and Boltzmann like schemes. Here we show that the use of such local scattering approaches within the Wigner function formalism may lead to unphysical results, namely anomalous suppression of intersubband relaxation, incorrect thermalization dynamics, and violation of probability density positivity. Furthermore, we propose a quantum mechanical generalization of relaxation time and Boltzmann like models, resulting in nonlocal scattering superoperators that enable one to overcome such limitations.", "author_names": [ "Rita Claudia Iotti", "Fabrizio Dolcini", "Fausto Rossi" ], "corpus_id": 59362146, "doc_id": "59362146", "n_citations": 15, "n_key_citations": 1, "score": 0, "title": "Wigner function formalism applied to semiconductor quantum devices: Need for nonlocal scattering models", "venue": "", "year": 2017 }, { "abstract": "Rationale: Despite growing use of engineered nanomaterials (ENM) in applications from electronics to medicine, the potential risk to human health remains a critical concern within clinical use. ENM exposure during pregnancy can potentially cause reproductive toxicity even at levels that produce no measurable harm to animals in normal conditions. Methods: Phospholipid micelle encapsulated CdSe/CdS/ZnS semiconductor nanocrystals with an average hydrodynamic diameter of 60 nm were intravenously injected during pregnancy in both rodent and nonhuman primate animal models. Cadmium concentration levels and maternal haematological and biochemical markers were determined, along with histopathological examination of major organs. Results: Nanocrystals were found to have crossed the placenta from mother to fetus in both rodents and nonhuman primates. However, the animal models display different responses with respect to reproductive toxicity. In the rodent model, toxicity symptoms are absent in treated subjects, with no observed gestational or fetal abnormalities and complications. A significantly higher miscarriage rate of 60% is recorded for macaques after prenatal nanoparticle administration. There was a miscarriage rate of 15% in the general population despite only ~0.16% of the initial cadmium dose present in the fetus. Blood and biochemical markers of treated macaques indicate acute hepatocellular injury within a week after nanoparticle administration. Histology of major organs of the miscarried macaque fetuses show no abnormalities. Conclusion: The potential of nanomaterials to cross the placenta and impact fetal survival in primates suggest the necessity of precautionary measures to prevent gestational exposure of ENMs.", "author_names": [ "Ling Ye", "Rui Hu", "Liwei Liu", "Jianwei Liu", "Jing Liu", "Hongyan Chen", "Ya-zhuo Hu", "Ya-qian Liu", "Xin Liu", "Cui Liu", "Danny Jian Hang Tng", "Yuanguang Meng", "Junle Qu", "Mark T Swihart", "Ken-Tye Yong" ], "corpus_id": 54175248, "doc_id": "54175248", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Comparing Semiconductor Nanocrystal Toxicity in Pregnant Mice and Non Human Primates", "venue": "Nanotheranostics", "year": 2019 }, { "abstract": "This paper presents a methodology to quantify oxidizing and reducing gases using n type and p type chemiresistive sensors, respectively. Low temperature sensor heating with pulsed UV or visible light modulation is used together with the application of the fast Fourier transform (FFT) to extract sensor response features. These features are further processed via principal component analysis (PCA) and principal component regression (PCR) for achieving gas discrimination and building concentration prediction models with R2 values up to 98% and RMSE values as low as 5% for the total gas concentration range studied. UV and visible light were used to study the influence of the light wavelength in the prediction model performance. We demonstrate that n type and p type sensors need to be used together for achieving good quantification of oxidizing and reducing species, respectively, since the semiconductor type defines the prediction model's effectiveness towards an oxidizing or reducing gas. The presented method reduces considerably the total time needed to quantify the gas concentration compared with the results obtained in a previous work. The use of visible light LEDs for performing pulsed light modulation enhances system performance and considerably reduces cost in comparison to previously reported UV light based approaches.", "author_names": [ "Ernesto Gonzalez", "Juan Casanova-Chafer", "Aanchal Alagh", "Alfonso Romero", "Xavier Vilanova", "Selene Acosta", "Damien Cossement", "Carla Bittencourt", "Eduard Llobet" ], "corpus_id": 235298853, "doc_id": "235298853", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "On the Use of Pulsed UV or Visible Light Activated Gas Sensing of Reducing and Oxidising Species with WO3 and WS2 Nanomaterials", "venue": "Sensors", "year": 2021 }, { "abstract": "Abstract Zn 1 x Er x O polycrystalline nanoparticles with various compositions x 0.01 0.02 0.03 0.04 0.05 and 0.10 were prepared using sol gel techniques, for which zinc acetate dihydrate and erbium 2 4 pentanedionate are used as precursors. Nanoparticles were pressed under a pressure of 4 tons for 5 min into disk shaped compacts with 2 mm thicknesses and 10 mm diameters. The pressed samples were annealed at 400 degC for 30 min. X ray diffraction (XRD) scanning electron microscopy (SEM) and Vickers microhardness analyses of the produced Er doped ZnO bulk nanomaterials were performed. Specifically, in this study we focused on the analysis of their mechanical properties. Undoped and Er doped bulk samples were investigated according to Meyer's law; the proportional sample resistance (PSR) elastic/plastic deformation (EPD) and indentation induced cracking (IIC) models; and the Hays Kendal (HK) approach. As a result, the IIC model was more suitable to determine the micromechanical properties and the reverse indentation size effect R ISE behavior of Er doped ZnO semiconductors.", "author_names": [ "Elif Asikuzun", "O Ozturk" ], "corpus_id": 139429705, "doc_id": "139429705", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Comparison of theoretical and experimental microhardness of tetrahedral binary Zn1 xErxO semiconductor polycrystalline nanoparticles", "venue": "Ceramics International", "year": 2019 }, { "abstract": "In the last two decades, colloidal semiconductor nanocrystals have emerged as a phenomenal research topic due to their size dependent optoelectronic properties and to their outstanding versatility in many technological applications. In this review, we provide an historical account of the most relevant computational works that have been carried out to understand atomistically the electronic structure of these materials, including the main requirements needed for the preparation of nanocrystal models that align well with the experiments. We further discuss how the advancement of these computational tools has affected the analysis of these nanomaterials over the years. We focus our review on the three main families of colloidal semiconductor nanocrystals: group II VI and IV VI metal chalcogenides, group III V metal pnictogenides and metal halides, in particular lead based halide perovskites. We discuss the most recent research frontiers and outline the future outlooks expected in this field from a computational perspective.", "author_names": [ "R Pascazio", "Juliette Zito", "I Infante" ], "corpus_id": 235072989, "doc_id": "235072989", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "An Overview of Computational Studies on Colloidal Semiconductor Nanocrystals.", "venue": "Chimia", "year": 2021 }, { "abstract": "On decreasing size down to nanoscale, the physical, optical and quantum mechanical properties of the materials no longer remain constant but become tuneable. In order to understand these unusual properties of nanomaterials, some theoretical models and experiments have been proposed from various perspectives. The explanation of energy band gap increment can be presented in terms of quantum confinement effect. A simple model based on cohesive and activation energy, free from adjustable parameters to calculate the size and shape dependent band gap expansion is derived for the semiconductor nanocompounds. The model predicts that the energy band gap increases on decreasing the size of the particle of nanomaterial semiconductors. Also, it is seen that the effects of shape alter the band gap energy of nanomaterials and this effect on band gap energy becomes larger with the decrease in particle size. Our predictions are very consistent with the available experimented data and the simulation results.", "author_names": [ "Madan Singh", "Abhishek Singhal" ], "corpus_id": 195697674, "doc_id": "195697674", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Modeling of Shape and Size Effects for the Band Gap of Semiconductor Nanoparticles", "venue": "2018 2nd International Conference on Micro Electronics and Telecommunication Engineering (ICMETE)", "year": 2018 } ]

[ { "abstract": "Atomic force microscopy based infrared spectroscopy (AFM IR) is a rapidly emerging technique that provides chemical analysis and compositional mapping with spatial resolution far below conventional optical diffraction limits. AFM IR works by using the tip of an AFM probe to locally detect thermal expansion in a sample resulting from absorption of infrared radiation. AFM IR thus can provide the spatial resolution of AFM in combination with the chemical analysis and compositional imaging capabilities of infrared spectroscopy. This article briefly reviews the development and underlying technology of AFM IR, including recent advances, and then surveys a wide range of applications and investigations using AFM IR. AFM IR applications that will be discussed include those in polymers, life sciences, photonics, solar cells, semiconductors, pharmaceuticals, and cultural heritage. In the Supporting Information the authors provide a theoretical section that reviews the physics underlying the AFM IR measurement and detection mechanisms.", "author_names": [ "Alexandre Dazzi", "Craig B Prater" ], "corpus_id": 29301657, "doc_id": "29301657", "n_citations": 354, "n_key_citations": 8, "score": 3, "title": "AFM IR: Technology and Applications in Nanoscale Infrared Spectroscopy and Chemical Imaging.", "venue": "Chemical reviews", "year": 2017 }, { "abstract": "Single molecule atomic force microscopy (AFM) was used to investigate the mechanical properties of titin, the giant sarcomeric protein of striated muscle. Individual titin molecules were repeatedly stretched, and the applied force was recorded as a function of the elongation. At large extensions, the restoring force exhibited a sawtoothlike pattern, with a periodicity that varied between 25 and 28 nanometers. Measurements of recombinant titin immunoglobulin segments of two different lengths exhibited the same pattern and allowed attribution of the discontinuities to the unfolding of individual immunoglobulin domains. The forces required to unfold individual domains ranged from 150 to 300 piconewtons and depended on the pulling speed. Upon relaxation, refolding of immunoglobulin domains was observed.", "author_names": [ "M Rief", "Mathias Gautel", "Filipp Oesterhelt", "J M Fernandez", "Hermann Eduard Gaub" ], "corpus_id": 7628383, "doc_id": "7628383", "n_citations": 2561, "n_key_citations": 120, "score": 0, "title": "Reversible unfolding of individual titin immunoglobulin domains by AFM.", "venue": "Science", "year": 1997 }, { "abstract": "Currently, biomechanics of living cells is in the focus of interest due to noticeable capability of such techniques like atomic force microscopy (AFM) to probe cellular properties at the single cell level directly on living cells. The research carried out, so far, delivered data showing, on the one hand, the use of cellular mechanics as a biomarker of various pathological changes, which, on the other hand, reveal relative nature of biomechanics. In the AFM, the elastic properties of living cells are delivered from indentation experiments and described quantitatively by Young's modulus defined here as a measure of cellular deformability. Here, the AFM studies directly comparing the mechanical properties of normal and cancerous cells are summarized and presented together with a few important issues related to the relativeness of Young's modulus.", "author_names": [ "Malgorzata Lekka" ], "corpus_id": 11931031, "doc_id": "11931031", "n_citations": 205, "n_key_citations": 7, "score": 0, "title": "Discrimination Between Normal and Cancerous Cells Using AFM", "venue": "BioNanoScience", "year": 2016 }, { "abstract": "High resolution Atomic Force Microscopy (AFM) and Scanning Tunnelling Microscopy (STM) imaging with functionalized tips is well established, but a detailed understanding of the imaging mechanism is still missing. We present a numerical STM/AFM model, which takes into account the relaxation of the probe due to the tip sample interaction. We demonstrate that the model is able to reproduce very well not only the experimental intra and intermolecular contrasts, but also their evolution upon tip approach. At close distances, the simulations unveil a significant probe particle relaxation towards local minima of the interaction potential. This effect is responsible for the sharp sub molecular resolution observed in AFM/STM experiments. In addition, we demonstrate that sharp apparent intermolecular bonds should not be interpreted as true hydrogen bonds, in the sense of representing areas of increased electron density. Instead they represent the ridge between two minima of the potential energy landscape due to neighbouring atoms.", "author_names": [ "Prokop Hapala", "Georgy Kichin", "Christian Wagner", "F Stefan Tautz", "Ruslan Temirov", "Pavel Jelinek" ], "corpus_id": 53610973, "doc_id": "53610973", "n_citations": 278, "n_key_citations": 7, "score": 0, "title": "Mechanism of high resolution STM/AFM imaging with functionalized tips", "venue": "", "year": 2014 }, { "abstract": "A current challenge in the life sciences is to understand how biological systems change their structural, biophysical and chemical properties to adjust functionality. Addressing this issue has been severely hampered by the lack of methods capable of imaging biosystems at high resolution while simultaneously mapping their multiple properties. Recent developments in force distance (FD) curve based atomic force microscopy (AFM) now enable researchers to combine (sub)molecular imaging with quantitative mapping of physical, chemical and biological interactions. Here we discuss the principles and applications of advanced FD based AFM tools for the quantitative multiparametric characterization of complex cellular and biomolecular systems under physiological conditions.", "author_names": [ "Yves F Dufrene", "David Martinez-Martin", "Izhar D Medalsy", "David Alsteens", "Daniel J Muller" ], "corpus_id": 7999717, "doc_id": "7999717", "n_citations": 327, "n_key_citations": 8, "score": 0, "title": "Multiparametric imaging of biological systems by force distance curve based AFM", "venue": "Nature Methods", "year": 2013 }, { "abstract": "The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge balancing anions in the interlayer. It is known that these phases present different hydration states (i.e. varying water content) depending on the relative humidity (RH) temperature and anion type, which might be linked to volume changes (swelling and shrinkage) Unfortunately the stability conditions of these phases are insufficiently reported. This paper presents novel experimental results on the different hydration states of the most important AFm phases: monocarboaluminate, hemicarboaluminate, stratlingite, hydroxy AFm and monosulfoaluminate, and the thermodynamic properties associated with changes in their water content during absorption/desorption. This data opens the possibility to model the response of cementitious systems during drying and wetting and to engineer systems more resistant to harsh external conditions. (C) 2015 Elsevier Ltd. All rights reserved.", "author_names": [ "Luis G Baquerizo", "Thomas Matschei", "Karen Scrivener", "Mahsa Saeidpour", "Lars Wadso" ], "corpus_id": 97636564, "doc_id": "97636564", "n_citations": 125, "n_key_citations": 2, "score": 0, "title": "Hydration states of AFm cement phases", "venue": "", "year": 2015 }, { "abstract": "Polymer and life science applications of a technique that combines atomic force microscopy (AFM) and infrared (IR) spectroscopy to obtain nanoscale IR spectra and images are reviewed. The AFM IR spectra generated from this technique contain the same information with respect to molecular structure as conventional IR spectroscopy measurements, allowing significant leverage of existing expertise in IR spectroscopy. The AFM IR technique can be used to acquire IR absorption spectra and absorption images with spatial resolution on the 50 to 100 nm scale, versus the scale of many micrometers or more for conventional IR spectroscopy. In the life sciences, experiments have demonstrated the capacity to perform chemical spectroscopy at the sub cellular level. Specifically, the AFM IR technique provides a label free method for mapping IR absorbing species in biological materials. On the polymer side, AFM IR was used to map the IR absorption properties of polymer blends, multilayer films, thin films for active devices such as organic photovoltaics, microdomains in a semicrystalline polyhydroxyalkanoate copolymer, as well as model pharmaceutical blend systems. The ability to obtain spatially resolved IR spectra as well as high resolution chemical images collected at specific IR wavenumbers was demonstrated. Complementary measurements mapping variations in sample stiffness were also obtained by tracking changes in the cantilever contact resonance frequency. Finally, it was shown that by taking advantage of the ability to arbitrarily control the polarization direction of the IR excitation laser, it is possible to obtain important information regarding molecular orientation in electrospun nanofibers.", "author_names": [ "Alexandre Dazzi", "Craig B Prater", "Qichi Hu", "D Bruce Chase", "John F Rabolt", "Curtis Marcott" ], "corpus_id": 13778137, "doc_id": "13778137", "n_citations": 317, "n_key_citations": 7, "score": 0, "title": "AFM IR: Combining Atomic Force Microscopy and Infrared Spectroscopy for Nanoscale Chemical Characterization", "venue": "Applied spectroscopy", "year": 2012 }, { "abstract": "The stiffness of cancer cells and its changes during metastasis are very important for understanding the pathophysiology of cancer cells and the mechanisms of metastasis of cancer. As the first step of the studies on the mechanics of cancer cells during metastasis, we determined the elasticity and stiffness of cancer cells with an indentation method using an atomic force microscope (AFM) and compared with those of normal cells. In most of the past AFM studies, Young's elastic moduli of cells have been calculated from force indentation data using Hertzian model. As this model is based on several important assumptions including infinitesimal strain and Hooke's linear stress strain law, in the exact sense it cannot be applied to cells that deform very largely and nonlinearly. To overcome this problem, we previously proposed an equation F=a[exp(bd) 1] to describe relations between force (F) and indentation (d) where a and b are parameters relating with cellular stiffness. In the present study, we applied this method to cancer cells instead of Young's elastic modulus. The conclusions obtained are: 1) AFM indentation test data of cancer cells can be very well described by the above equation, 2) cancer cells are softer than normal cells, and 3) there are no significant locational differences in the stiffness of cancer cells between the central and the peripheral regions. These methods and results are useful for studying the mechanics of cancer cells and the mechanisms of metastasis.", "author_names": [ "Kozaburo Hayashi", "Mayumi Iwata" ], "corpus_id": 26019858, "doc_id": "26019858", "n_citations": 92, "n_key_citations": 2, "score": 0, "title": "Stiffness of cancer cells measured with an AFM indentation method.", "venue": "Journal of the mechanical behavior of biomedical materials", "year": 2015 }, { "abstract": "An atomic force microscope (AFM) is an extremely versatile investigative tool in the field of nanotechnology, the performance of which is significantly influenced by its conventional zig zag raster pattern scanning method. In this paper, in order to increase its imaging speed, we consider the use of a sinusoidal scanning method, i.e. a spiral scanning method with an improved model predictive control (MPC) scheme. In this approach, spirals are generated by applying waves, each with a single frequency and slowly varying amplitude, in the X piezo (sine wave) and Y piezo (cosine wave) of the piezoelectric tube scanner (PTS) of the AFM. As these input signals are single frequencies, the scanning can proceed faster than traditional raster scanning, without exciting the resonant mode of the PTS. The proposed MPC controller reduces the phase error between the reference position input and measured output sinusoids and provides better tracking of the reference signal. Also, a notch filter is designed and included in the feedback loop to suppress vibrations of the PTS at the resonant frequency. The experimental results show that, using the proposed method, the AFM is able to scan a 6 mm radius image within 2.04 s with a quality better than that obtained using the conventional raster pattern scanning method.", "author_names": [ "M S Rana", "Hemanshu Roy Pota", "Ian R Petersen" ], "corpus_id": 34730060, "doc_id": "34730060", "n_citations": 69, "n_key_citations": 2, "score": 0, "title": "Performance of Sinusoidal Scanning With MPC in AFM Imaging", "venue": "IEEE/ASME Transactions on Mechatronics", "year": 2015 }, { "abstract": "The ability to perturb individual cells and to obtain information at the single cell level is of central importance for addressing numerous biological questions. Atomic force microscopy (AFM) offers great potential for this prospering field. Traditionally used as an imaging tool, more recent developments have extended the variety of cell manipulation protocols. Fluidic force microscopy (FluidFM) combines AFM with microfluidics via microchanneled cantilevers with nano sized apertures. The crucial element of the technology is the connection of the hollow cantilevers to a pressure controller, allowing their operation in liquid as force controlled nanopipettes under optical control. Proof of concept studies demonstrated a broad spectrum of single cell applications including isolation, deposition, adhesion and injection in a range of biological systems.", "author_names": [ "Orane Guillaume-Gentil", "Eva Potthoff", "Dario Ossola", "Clemens M Franz", "Tomaso Zambelli", "Julia A Vorholt" ], "corpus_id": 20705558, "doc_id": "20705558", "n_citations": 114, "n_key_citations": 1, "score": 0, "title": "Force controlled manipulation of single cells: from AFM to FluidFM.", "venue": "Trends in biotechnology", "year": 2014 } ]

[ { "abstract": "This paper presents an analog front end transceiver for an ultrasound imaging system based on a high voltage (HV) transmitter, a low noise front end amplifier (RX) and a complementary metal oxide semiconductor, aluminum nitride, piezoelectric micromachined ultrasonic transducer (CMOS AlN PMUT) The system was designed using the 0.13 mm Silterra CMOS process and the MEMS on CMOS platform, which allowed for the implementation of an AlN PMUT on top of the CMOS integrated circuit. The HV transmitter drives a column of six 80 mm square PMUTs excited with 32 V in order to generate enough acoustic pressure at a 2.1 mm axial distance. On the reception side, another six 80 mm square PMUT columns convert the received echo into an electric charge that is amplified by the receiver front end amplifier. A comparative analysis between a voltage front end amplifier (VA) based on capacitive integration and a charge sensitive front end amplifier (CSA) is presented. Electrical and acoustic experiments successfully demonstrated the functionality of the designed low power analog front end circuitry, which outperformed a state of the art front end application specific integrated circuit (ASIC) in terms of power consumption, noise performance, and area.", "author_names": [ "Ivan Zamora", "Eyglis Ledesma", "Arantxa Uranga", "Nuria Barniol" ], "corpus_id": 211523967, "doc_id": "211523967", "n_citations": 9, "n_key_citations": 2, "score": 0, "title": "Miniaturized 0.13 mm CMOS Front End Analog for AlN PMUT Arrays", "venue": "Sensors", "year": 2020 }, { "abstract": "This article presents a fully integrated ultrasound system based on a single piezoelectric micromachined ultrasonic transducer (PMUT) monolithically fabricated with a <inline formula> <tex math notation=\"LaTeX\"$0.13~\\mu \\text{m} /tex math>/inline formula> complementary metal oxide semiconductor (CMOS) process analog front end circuitry. The PMUT consists of an aluminum nitride, AlN, squared device with <inline formula> <tex math notation=\"LaTeX\"$80~\\mu \\text{m} /tex math>/inline formula> side that resonates at 2.4 MHz in liquid environment. The monolithic integration of the PMUT with the CMOS circuitry allows a reduction of the parasitic capacitance, a reduction of the electronic noise contribution and a clear improvement in the Signal to Noise ratio (SNR 27 dB better) compared to a non integrated equivalent system. A pulse echo experiment with the single PMUT on CMOS for transmitting and sensing simultaneously is demonstrated, ensuring a 17.3 dB SNR, higher than the minimal necessary for accurate fingerprint images, paving the way towards a pixel sized imaging system with no need of multiple simultaneous PMUTs transmitters. Consuming only 0.3 mW and getting an input referred noise of 3.26 mPa/<inline formula> <tex math notation=\"LaTeX\"\\surd /tex math>/inline formula>Hz at 2.4 MHz, the proposed pulse echo system achieves a competitive noise efficient factor in comparison with the state of the art.", "author_names": [ "Ivan Zamora", "Eyglis Ledesma", "Arantxa Uranga", "Nuria Barniol" ], "corpus_id": 221193488, "doc_id": "221193488", "n_citations": 7, "n_key_citations": 3, "score": 0, "title": "Monolithic Single PMUT on CMOS Ultrasound System With +17 dB SNR for Imaging Applications", "venue": "IEEE Access", "year": 2020 }, { "abstract": "Microelectromechanical system (MEMS) based mass sensors are proposed as potential candidates for highly sensitive chemical and gas detection applications owing to their miniaturized structure, low power consumption, and ease of integration with readout circuits. This paper presents a new approach in developing micromachined mass sensors based on capacitive and piezoelectric transducer configurations for use in low concentration level gas detection in a complex environment. These micromachined sensors operate based on a shift in their center resonant frequencies. This shift is caused by a change in the sensor's effective mass when exposed to the target gas molecules, which is then correlated to the gas concentration level. In this work, capacitive and piezoelectric based micromachined sensors are investigated and their principle of operation, device structures and configurations, critical design parameters and their candidate fabrication techniques are discussed in detail.", "author_names": [ "Haleh Nazemi", "Jenitha Antony Balasingam", "Siddharth Swaminathan", "Kenson Ambrose", "Muhammad Umair Nathani", "Tara Ahmadi", "Yameema Babu Lopez", "Arezoo Emadi" ], "corpus_id": 215410352, "doc_id": "215410352", "n_citations": 12, "n_key_citations": 1, "score": 0, "title": "Mass Sensors Based on Capacitive and Piezoelectric Micromachined Ultrasonic Transducers CMUT and PMUT", "venue": "Sensors", "year": 2020 }, { "abstract": "In this work, a waterproof tent plate piezoelectric micromachined ultrasonic transducer (PMUT) with enhanced performance as actuator and sensor in comparison with standard clamped PMUT is presented. The squared AlN PMUT has four linear holes that are sealed by the passive layer allowing to increase the movement and giving the capability to work in liquid environment. The dimension of the holes was optimized to increase the PMUT displacement at least twice in relation with the regular clamped device. The acoustic performance of the PMUT was simulated in COMSOL Multiphysics and the results were experimentally verified under liquid operation. The experimental transmitting sensitivity, 3.9 kPa/V, as well as the sensor sensitivity, 13.4 V/MPa, provide a 2x factor improvement in contrast with the clamped PMUT with competitive values. Additionally, the presented tent plate PMUT provides advantages in relation with the area, cost, power consumption and imaging quality thanks to the capability to be monolithically integrated over CMOS substrates.", "author_names": [ "Eyglis Ledesma", "Ivan Zamora", "Arantxa Uranga", "Nuria Barniol" ], "corpus_id": 219459962, "doc_id": "219459962", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Tent Plate AlN PMUT With a Piston Like Shape Under Liquid Operation", "venue": "IEEE Sensors Journal", "year": 2020 }, { "abstract": "In this paper, we present the design, fabrication, and characterization of a compact <inline formula> <tex math notation=\"LaTeX\"$4\\times 4$ /tex math>/inline formula> piezoelectric micromachined ultrasonic transducer (pMUT) array and its application to photoacoustic imaging. The uniqueness of this pMUT array is the integration of a <inline formula> <tex math notation=\"LaTeX\"$4~\\mu \\text{m} /tex math>/inline formula> thick ceramic PZT, having significantly higher piezoelectric coefficient and lower stress than sol gel or sputtered PZT. The fabricated pMUT array has a small chip size of only <inline formula> <tex math notation=\"LaTeX\"$1.8\\times1.6$ /tex math>/inline formula> mm² with each pMUT element having a diameter of <inline formula> <tex math notation=\"LaTeX\"$210~\\mu \\text{m} /tex math>/inline formula> The fabricated device was characterized with electrical impedance measurement and acoustic sensing test. Photoacoustic imaging has also been successfully demonstrated on an agar phantom with a pencil lead embedded using the fabricated pMUT array. [2020 0087]", "author_names": [ "Haoran Wang", "Zhenfang Chen", "Hao Yang", "Huabei Jiang", "Huikai Xie" ], "corpus_id": 222219562, "doc_id": "222219562", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "A Ceramic PZT Based PMUT Array for Endoscopic Photoacoustic Imaging", "venue": "Journal of Microelectromechanical Systems", "year": 2020 }, { "abstract": "This paper presents the design and fabrication method to render a silicon on insulator (SOI) based pMUT array bendable. The proposed method can be applied to silicon based pMUT arrays with different acoustical specifications. A bendable array based on the proposed method is highly conformal to the target structure. The bendable structure is made out of several silicon islands containing a pMUT array and are connected to each other by silicon springs. The silicon springs are realized by deep reactive ion etching (DRIE) that was also used to create the pMUT membranes. The fabrication process requires one additional photomask step compared to a process that realizes only pMUTs. Since the pMUT arrays are fabricated on silicon islands with the thickness of the entire SOI wafer, therefore their performance is not compromised. As a case study, a bendable array was designed and fabricated to be wrapped around a <inline formula> <tex math notation=\"LaTeX\"$5\\times 5\\times 5$ /tex math>/inline formula> mm³ 3D printed cube. Therefore, each bendable array has 6 islands with a dimension of <inline formula> <tex math notation=\"LaTeX\"$3\\times 3$ /tex math>/inline formula> mm² including <inline formula> <tex math notation=\"LaTeX\"$3\\times 3$ /tex math>/inline formula> pMUT array, of which each pMUT has a diameter of 410 <inline formula> <tex math notation=\"LaTeX\"\\mu \\text{m} /tex math>/inline formula> and a thickness of 6 <inline formula> <tex math notation=\"LaTeX\"\\mu \\text{m} /tex math>/inline formula> with a 1 <inline formula> <tex math notation=\"LaTeX\"\\mu \\text{m} /tex math>/inline formula> Lead Zirconate Titanate (PZT) layer as the piezoelectric material. The silicon springs in between each island have a spring constant of 2.3 (N/m) in their folding direction. This compliant structure enables a 90deg bending with a bending radius of 1 mm. The pMUT elements in the array resulted in a displacement response of 2.1 <inline formula> <tex math notation=\"LaTeX\"\\mu \\text{m} /tex math>/inline formula>/V and a Q factor of 104 at 426 kHz, when all arrays were excited all together. [2019 0224]", "author_names": [ "Sina Sadeghpour", "Bram Lips", "Michael Kraft", "Robert Puers" ], "corpus_id": 216231579, "doc_id": "216231579", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Bendable Piezoelectric Micromachined Ultrasound Transducer (PMUT) Arrays Based on Silicon On Insulator (SOI) Technology", "venue": "Journal of Microelectromechanical Systems", "year": 2020 }, { "abstract": "A compact single cell piezoelectric micromachined ultrasound transducer (PMUT) with dual electrodes is designed, fabricated, and used to measure the density of a fluid mixture mimicking the range of human blood density variation. The sensor's novelty lies in its compactness enabled by on device sensing and actuation due to the dual electrodes. The active material used here is thin film PZT which is protected from the fluid environment with an appropriate coating. The results obtained show a linear response of the sensor output over the density range of interest with no appreciable degradation in the signal due to immersion in a fluid. The sensitivity of the sensor is 191 Hz/Kg/m3. These single cell PMUTs are, therefore, potential candidates for fluid density monitoring in industrial or biomedical applications.", "author_names": [ "Kaustav Roy", "Avinandan Mandal", "Anuj Ashok", "Harshvardhan Gupta", "Vijayendra Shastri", "Rudra Pratap" ], "corpus_id": 227064632, "doc_id": "227064632", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "A Single Cell PMUT as a Bio Fluid Density Sensor", "venue": "2020 IEEE International Ultrasonics Symposium (IUS)", "year": 2020 }, { "abstract": "This work presents a new type of piezoelectric micromachined ultrasonic transducer (PMUT) based on a bi stable MEMS membrane structure with integrated aluminum nitride (AlN) actuators. By switching the membrane between both stable ground states, large, design dependent membrane center displacements in the range of $10~\\mu \\text{m} can be achieved, which result in sound pressure levels of up to 96.8 dB in the ultrasonic range at frequencies between 30 and 60 kHz at a distance of 10.5 mm. This bi stable operation mode can be triggered by moderate voltage levels of up to 40 V, which is not uncommon for PMUT devices. The usage of AlN compared to the more commonly utilized lead zirconate titanates (PZT) significantly simplifies the device integration process and ensures CMOS compatibility. A comprehensive comparison with similar devices in literature shows that despite the lower piezoelectric coefficients of AlN compared to PZT, this bi stable actuation approach features exceptionally high stroke levels with a correspondingly high overall sound pressure level. [2020 0104]", "author_names": [ "Michael Schneider", "M Dorfmeister", "Philipp Moll", "Manfred Kaltenbacher", "Ulrich Schmid" ], "corpus_id": 222221629, "doc_id": "222221629", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Bi Stable Aluminum Nitride Based Piezoelectric Micromachined Ultrasonic Transducer (PMUT)", "venue": "Journal of Microelectromechanical Systems", "year": 2020 }, { "abstract": "This work presents theoretical analysis and finite element simulations of a novel piezoelectric micromachined ultrasonic transducer (pMUT) design. A pMUT with free boundary condition is introduced for the first time and compared with conventional pMUTs of fixed boundary. For the same transducer dimensions, the proposed design has more than 2.5x electromechanical coupling coefficient compared to that from traditional clamped boundary design due to increased mechanical capacitance by the free edge. The cavity underneath the disc behaves as an acoustic resonator. By matching the frequencies of mechanical and acoustical resonances, the fractional bandwidth of the free boundary pMUT has 13x more fractional bandwidth compared to that of the fixed boundary design. In addition, the internal stresses created during microfabrication are expected to be released with the free edges. These results indicate that free pMUTs have the potential for high performance ultrasonic transducer applications.", "author_names": [ "Sedat Pala", "Liwei Lin" ], "corpus_id": 227064262, "doc_id": "227064262", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Piezoelectric Micromachined Ultrasonic Transducers (pMUT) with Free Boundary", "venue": "2020 IEEE International Ultrasonics Symposium (IUS)", "year": 2020 }, { "abstract": "This paper proposed impact of geometrical dimension for circular shaped aluminum nitride (AIN) based piezoelectric micromachined ultrasonic transducer (PMUT) for achieving best operating performance. The PMUT is focusing on 25 35 MHz frequency for biomedical application. Thus, this paper investigates the minimum geometrical dimension of PMUT with limitation of CMOS compatible process by using finite element analysis (FEA) ONSCALE software. This paper proposed comparative study that focused on AlN thickness and substrate diameter for PMUT in order to determine better design for better PMUT performance. Finite element analysis (FEA) of ONSCALE software was used for numerical analysis simulation. The simulation was carried out for AlN thickness and substrate diameter for impact study on PMUT performance with CMOS limitation. The PMUT displacement performances and frequencies for different AIN thickness and substrate diameter are analyzed. Firstly, the PMUT performance is analyzed for AlN thickness when the substrate diameter and cavity height are fixed. Secondly, the PMUT performance is analyzed for substrate diameter when the AlN thickness and cavity height are fixed. In this work, for frequency 25 35 MHz, the maximum PMUT displacement is achieved at AlN thickness \\mathbf{1.1} \\mu\\mathbf{m} substrate diameter \\mathbf{22.5} \\mu\\mathbf{m} and cavity height \\mathbf{3.0} \\mu\\mathbf{m} The substrate diameter has no impact for PMUT displacement when the AlN thickness and cavity height is fixed. This work provides helpful information for designing PMUT for better performance of displacement.", "author_names": [ "Muhammad Naim Haron", "Mohamad Adzhar Md Zawawi", "Mohamed Fauzi Packeer", "Asrulnizam Bin Abd Manaf" ], "corpus_id": 219858636, "doc_id": "219858636", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Geometrical dimension impact for performance of CMOS based circular shape aluminum nitride (AlN) piezoelectric micromachined ultrasonic transducer (PMUT)", "venue": "2020 4th IEEE Electron Devices Technology Manufacturing Conference (EDTM)", "year": 2020 } ]

[ { "abstract": "Abstract A Photovoltaic cell is an electrical gadget that changes over light legitimately into power by photovoltaic impact. Semiconductor materials are the fundamental materials they are made of. Cells are intended to deal with daylight and are made of single intersection or multijunction for different retention and charge partition instrument. Sun based cell configuration includes determining the parameters of a solar cell structure to expand proficiency. Effectiveness of a sun oriented cell basically relies upon Grid components (Ribbon, Busbar, Pad and Finger) Textures, materials and formats. Ray Tracing and Surface Morphology with different periodicity also influences the efficiency of Solar Cell due to change in Photo Current Densities. In this paper, SEM investigation and surface morphology are performed on lattice components of both mono and poly crystalline sunlight based cells which legitimately impacts cell effectiveness.", "author_names": [ "Suresh Kumar Tummala", "Satyanarayana Kosaraju" ], "corpus_id": 216180251, "doc_id": "216180251", "n_citations": 11, "n_key_citations": 0, "score": 1, "title": "SEM analysis of grid elements in mono crystalline and poly crystalline based solar cell", "venue": "", "year": 2020 }, { "abstract": "Abstract A copolymer of hydrochloric acid doped o anthranilic acid with o aminophenol (PAAOAP) was prepared in a highly acidic medium based on the oxidative polymerization in the presence of polyethylene glycol (PEG 200) as a soft template by ferric chloride initiator. The resulting doped hydrochloric acid copolymer (PAAOAP) was characterized by several techniques including FTIR, XRD, SEM, TGA, and UV Vis NIR spectrophotometer. A PAAOAP thin film was prepared by spin coating technique with a thickness of 200 3 nm. By applying the specific fabrication conditions summarized in the synthesis of polymer solar cell part and post production annealing at 323 k, the polymer solar cells were established with a power conversion efficiency of 8.23% Interesting thermal stability was studied for these devices. To improve the performance of heterojunction diodes, specific thermal annealing was employed. As a result, the conducting polymer crystallinity and nanoscale morphology were significantly enhanced resulting in improving the collection of charges at the electrode. By this way, the device efficiency was increased by reducing the series resistance of the polymer solar cells.", "author_names": [ "M Sh Zoromba", "Mohammed A Tashkandi", "Abdulmohsen Al Alshehri", "Mohammed H Abdel-Aziz", "Mohamed Bassyouni", "Safia A Mahmoud", "Ahmed Ben Slimane", "Ahmed F Al-Hossainy" ], "corpus_id": 218914862, "doc_id": "218914862", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Polymer solar cell based on doped o anthranilic acid and o aminophenol copolymer", "venue": "", "year": 2020 }, { "abstract": "Abstract ZnO nanorods doped with different concentrations of Ag and Nd (1 7% were synthesized by hydrothermal method. In this article we describe the synthesis, characterization and applications of pristine ZnO, Ag doped ZnO and Nd doped ZnO nanorods in hybrid bulk heterojunction solar cells. Their optical, structural, and morphological properties were analyzed by using UV Visible spectroscopy, X ray diffraction (XRD) Scanning electron microscopy (SEM) and Energy dispersive X ray spectroscopy (EDX) The X ray diffraction analysis reveals that the pristine and doped ZnO nanorods were crystallized in a hexagonal wurtzite structure. SEM images supplemented with EDX were used to explore the morphology, size and chemical composition of pristine ZnO, Ag doped ZnO and Nd doped ZnO samples. UV visible absorption spectra showed that bathochromic shift occurred when ZnO nanorods were doped with Ag and Nd up to a certain limit of dopant concentration. Doped ZnO nanorods were found more conducting than prisitne ZnO nanorods. This work also represents the chemical modification of pristine ZnO, Ag doped ZnO, and Nd doped ZnO nanorods with a bromopyrogallol red dye (Br PGR) which is not reported yet. The pristine and doped samples were sensitized with Br PGR and the material so sensitized was tested in solar cell. The optical properties of grafted samples were thoroughly studied by using UV visible spectroscopy. The Nano hybrid material was tested as a photoactive blend of the DSSCs and their current voltage measurements (I V) were performed to examine the effect of pristine and doped ZnO nanorods on the performance of solar cells. Moreover current voltage (I V) measurements confirmed the boosting of efficiency in pristine and doped ZnO nanorods based DSSCs owing to their sensitization with Br PGR. Maximum power conversion efficiency of 1% was recorded for Ag doped ZnO nanorods.", "author_names": [ "Abdus Saboor", "Syed Mujtaba Shah", "Hazrat Hussain" ], "corpus_id": 104351929, "doc_id": "104351929", "n_citations": 39, "n_key_citations": 1, "score": 0, "title": "Band gap tuning and applications of ZnO nanorods in hybrid solar cell: Ag doped verses Nd doped ZnO nanorods", "venue": "Materials Science in Semiconductor Processing", "year": 2019 }, { "abstract": "Abstract Zinc oxide (ZnO) is a potential semiconductor being investigated for a variety of applications as many are dependent upon its typical shape. Using hydrothermal method, ZnO nanorods are grown using equimolar solutions of Zinc nitrate and Hexamethylenetetramine (HMTA) This study aims to investigate the effects of temperature on morphology of the zinc oxide structures. HMTA beyond acting as a pH buffer, creates a steric interference at lower temperature which gives space for nanorod growth. At higher temperature, this effect is dominated by the excess of ammonia involvement cancelling the non polar chelation thereby resulting in rice shaped structures. These structures were characterized by SEM, XRD, RAMAN spectroscopy, UV Vis spectroscopy and photoluminescence. The dye sensitized solar cell (DSSC) performance is also studied. It is stipulated that though the nanorods show better efficiency, microrice has potential space for improvement.", "author_names": [ "A Saranya", "T Devasena", "H Sivaram", "Ramasamy Jayavel" ], "corpus_id": 103476164, "doc_id": "103476164", "n_citations": 23, "n_key_citations": 0, "score": 0, "title": "Role of hexamine in ZnO morphologies at different growth temperature with potential application in dye sensitized solar cell", "venue": "Materials Science in Semiconductor Processing", "year": 2019 }, { "abstract": "Abstract In this study, superstrate type ITO/TiO2/In2S3/C2ZnSnS4 thin film solar cells were investigated. We obtained thin film solar cells by using the facile, vacuum free solution process which has no require complex system. The C2ZnSnS4(CZTS) thin film was produced by solution process and dip coating technique on the glass substrate and annealed at 515 degC for 30 min under argon condition. The CZTS thin film was characterized by means of XRD, micro Raman, XPS, SEM EDX, AFM and UV Visible Spectrometer tools. The XRD result showed that the CZTS quaternary semiconductor crystallized in the kesterite phase formation. The Raman and X ray photo electron studies were conducted to support the formation of crystalline structure. The SEM and AFM images showed that the surfaces of substrate were covered with sub micron sized CZTS absorber without any cracks. The optical study revealed that the CZTS has a suitable band gap energy about ~1.65 eV for solar cell applications. All the layers of the CZTS solar cells including the transparent conductive oxide (TCO) ITO, TiO2/In2S3 buffers and CZTS absorber layers were also coated on the soda lime glass by the solution process, respectively. The ITO/TiO2/In2S3/CZTS device exhibited the solar conversion efficiency of 0.7% which was the first device that all layers including TCO obtained by means of the non vacuum processed solution method.", "author_names": [ "Ahmet Tumbul", "Ferhat Gurkan Aslan", "Abdullah Goktas", "Ibrahim Mutlu" ], "corpus_id": 139338012, "doc_id": "139338012", "n_citations": 30, "n_key_citations": 0, "score": 0, "title": "All solution processed superstrate type Cu2ZnSnS4 (CZTS) thin film solar cell: Effect of absorber layer thickness", "venue": "Journal of Alloys and Compounds", "year": 2019 }, { "abstract": "Abstract Silver:zinc nanocomposite (Ag:Zn BMNC) was successfully synthesized by chemical reduction method and employed in various layers of the device structure to fabricate efficient thin film organic solar cell. The photoactive layer of the solar cell is composed of poly(3 hexylthiophene) and [6,6] phenyl C61 butyric acidmethyl ester (P3HT:PCBM) The nanocomposites, loaded at various layers of the device structure, appeared to have different influences on the performance of the solar cells. The optical and electrical properties of the nano particles are found to be favourable to harvest solar radiation because of the local plasmon resonance effect (LPSR) of the metal nano particles. The concentration of Ag:Zn nano particle has been successfully optimized to achieve a high device performance which led to a power conversion efficiency as high as 5% under ambient laboratory condition. The x ray diffraction (XRD) Scanning and Tunnelling electron microscopies (SEM and TEM) were employed to investigate the nature of the nano composite.", "author_names": [ "Elhadi A A Arbab", "Genene Tessema Mola" ], "corpus_id": 106390991, "doc_id": "106390991", "n_citations": 19, "n_key_citations": 0, "score": 0, "title": "Metals decorated nanocomposite assisted charge transport in polymer solar cell", "venue": "Materials Science in Semiconductor Processing", "year": 2019 }, { "abstract": "Abstract This paper presents the impact of thickness of RF sputtered CdTe thin film as an absorber layer through structural and optical characterization in ZnxCd1 xS/CdTe solar cells at lower concentration of zinc (Zn) The crystallographic, morphological and optical properties of CdTe thin film fabricated on top of bare soda lime glass were elucidated by X ray diffraction (XRD) scanning electron microscopy (SEM) atomic force microscopy (AFM) and ultraviolet (UV) spectrophotometer. XRD spectra shows that crystallinity increases in thicker samples and the CdTe (1 1 1) diffraction peak intensity centered at 23.825deg increases with the increase of film thickness confirming the zinc blend structure of CdTe thin film. The window layer ZnxCd1 xS was fabricated with optimum deposition conditions by co sputtering of ZnS and CdS. The complete cell was fabricated by RF magnetron sputtering with the cell configuration of glass/FTO/ZnxCd1 xS/ZnTe/Ag. With the increasing thicknesses of CdTe the cell efficiency increases with the highest efficiency of 8.79% for 3.5 mm of CdTe. This paves the way of novel window of ZnCdTe for smoothening the junction mismatches in hetero junction CdTe thin film solar cells.", "author_names": [ "Mohammad S Hossain", "Kazi Sajedur Rahman", "Mohammad Rezaul Karim", "Mohammed Omer Aijaz", "Mushtaq Ahmad Dar", "Muhammad Ali Shar", "Halina Misran", "Nowshad Amin" ], "corpus_id": 127231701, "doc_id": "127231701", "n_citations": 20, "n_key_citations": 0, "score": 0, "title": "Impact of CdTe thin film thickness in ZnxCd1 xS/CdTe solar cell by RF sputtering", "venue": "Solar Energy", "year": 2019 }, { "abstract": "Poly(ortho phenylenediamine) (PoPDA) microrods with ladder type structure are synthesized in acidic medium (pH 0.5) at room temperature based on a developed and facile method. The molecular structure, thermal stability, and surface morphology of the microrods shaped PoPDA were described by different characterization techniques comprising FTIR, TGA, 1HNMR, and SEM. Optimized thin films of PoPDA were successfully fabricated by thermal deposition method. The thin film was characterized by XRD and AFM. Au/PoPDA/p Si/Al heterojunction diodes have been successfully fabricated. Dark current voltage and capacitance voltage characteristics were applied to get the particular parameters of the devices. Photovoltaic features of Au/PoPDA/p Si/Al heterojunction at various intensities of white light illumination are studied. Under optimized conditions, the fabricated planar heterojunction solar cells utilizing a 95 10 nm of PoPDA film exhibited a power conversion efficiency (PCE) of 5.64% (JSC 41.78 A/m2, VOC 0.36 V, and FF 28.11% The relatively small FF (at room temperature with IP) and Rs of the devices designate that by increasing of the absolute temperature, the photovoltaic performance of the solar cells can be improved.", "author_names": [ "M Sh Zoromba", "Mohamed Helmy Abdel-Aziz", "Mohamed Bassyouni", "Haitham Bahaitham", "Ahmed F Al-Hossainy" ], "corpus_id": 105117054, "doc_id": "105117054", "n_citations": 37, "n_key_citations": 1, "score": 0, "title": "Poly(o phenylenediamine) thin film for organic solar cell applications", "venue": "Journal of Solid State Electrochemistry", "year": 2018 }, { "abstract": "Abstract A highly efficient photovoltaic nanocomposite device is demonstrated by fabrication of structural clusters of silver nanoparticles (Ag NPs) on silicon solar cells via a boil deposition method. The efficiency of silicon solar cell was augmented by coating Ag NPs ultra thin film deposition on silicon solar cell. Chemically synthesized silver NP's, their consumption on a silicon thin layer and the operation of photovoltaic nanocomposite device were characterized by using several electron probe microscopic pectroscopic and spectrometric techniques viz. x ray diffraction (XRD) scanning electron microscopy (SEM) high resolution transmission electron microscopy (HR TEM) Photoluminescence, UV visible absorption, dielectric, current vs. voltage I V and capacitance vs. voltage C V characteristics. Poly dispersed nature of 'Ag' nanoparticles established the anisotropy of these NPs when coated on silicon solar cells. Their efficiency enhancement was confirmed from HR TEM image via time domain finite difference technique to deliberate the particle distribution effect on an ultra thin film of silicon solar cell, indicating the sufficient enrichment in the efficiency of solar cell. Furthermore, the current work explores the developement of novel glass frits for utilization in next generation of high efficiency smart solar cells.", "author_names": [ "Theivasanthi Thirugnanasambandan", "Kaushik Pal", "Anjali Sidhu", "M Abd Elkodous", "H Lakshmi Ram Prasath", "K Kulasekarapandian", "Abbas Ayeshamariam", "Jaison Jeevanandam" ], "corpus_id": 140053522, "doc_id": "140053522", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "Aggrandize efficiency of ultra thin silicon solar cell via topical clustering of silver nanoparticles", "venue": "", "year": 2018 }, { "abstract": "Abstract In the present study, we synthesized TiO2 nanofibers (NFs) by electrospinning technique and they were subject to solvosonication process using glycerol as a pore forming agent to produce porous TiO2 NFs. The prepared porous TiO2 NFs are seen to improve the light harvesting capability as a result of enhanced light scattering inside the TiO2 NFs and offer a high surface area for maximum adsorption of pre synthesized CdSe ~4 nm) QDs. The FE SEM and BET analysis were performed to confirm the surface texture and surface area of porous TiO2 NFs, respectively. Finally, QDSSCs were fabricated using these porous TiO2 NFs sensitized with CdSe QDs as the photoanode, Cu2S nanoparticles as the counter electrode and polysulfide redox couple (S2 /Sx2 as the electrolyte. The porous TiO2 NFs obtained by solvosonication at the time duration of 90 min has enhanced photocurrent density (Jsc) of 9.21 mA/cm2 with high power conversion efficiency (e) of 2.15% than the conventional TiO2 NFs (e 1.50%", "author_names": [ "Nisha Singh", "Zaahir Salam", "A Subasri", "Narayanappa Sivasankar", "Angaiah Subramania" ], "corpus_id": 104045444, "doc_id": "104045444", "n_citations": 40, "n_key_citations": 0, "score": 0, "title": "Development of porous TiO2 nanofibers by solvosonication process for high performance quantum dot sensitized solar cell", "venue": "", "year": 2018 } ]

[ { "abstract": "Abstract This chapter addresses the issues of the electron beam radiation damage that are commonly encountered during physical failure analysis (PFA) in the modern semiconductor industry by scanning electron microscopy, focus ion beam, and transmission electron microscopy. We discussed the effects of electron beam radiation on the phase, microstructure, and compositions of some typical electron beam sensitive materials used in semiconductor devices, such as low k and ultralow k dielectrics, silicon nitrides, and CoFeB ferromagnetic materials. Based on the detailed case study and analysis, we elaborated on the underlying mechanisms associated with the electron radiation of different materials. Meanwhile, comprehensive technical solutions were proposed to minimize the electron beam radiation damages during the PFA of these special types of materials.", "author_names": [ "Binghai Liu", "Xiaomin Li", "Younan Hua", "Nan Cho", "Zhili Dong", "Yuzhe Zhao", "Kenny Ong", "Zhiqiang Mo" ], "corpus_id": 210754799, "doc_id": "210754799", "n_citations": 1, "n_key_citations": 0, "score": 1, "title": "Electron beam radiation and its impacts to failure analysis in semiconductor industry", "venue": "", "year": 2020 }, { "abstract": "In view of the external thread fracture during casing running in a well in Xinjiang Oilfield, the failure reasons of thread fracture were analyzed by combining the theory with experiment, and the casing safe service window with harsh working conditions was given. The operation of the failed casing and determined the actual working conditions of the casing threaded joints during the running process were investigated in this paper. According to the theoretical method, the boundary conditions and load conditions of the fracture casing joint in service were determined. With the aid of full scale physical simulation test device, as well as the above boundary conditions and load conditions, the same batch casing tensile bearing characteristics were determined. Through nondestructive testing, the metallographic observation, scanning electron microscopy, spectral analysis and up and down test, the main controlling factors of casing thread fracture were determined. By the finite element analysis, the casing threads service state under axial tension and bending loads was established, the safety performance of threads under ideal working conditions was studied, and the fatigue mechanism of threads was revealed. Combined with the analysis results, the corresponding relationship between the casing tensile bearing characteristics and safety factor was given, which provides technical support for the safe service selection of casing body and thread under harsh conditions, saving cost and shortening the well construction period.", "author_names": [ "Rong Li Nan", "Xin Sun", "Bo Zhao Shu", "Hang Wang", "Shang-yu Yang", "Cai Hong Lu", "Li Hong Han" ], "corpus_id": 219311212, "doc_id": "219311212", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Threaded Failure Analysis for Three Dimensional Horizontal Wells Casing", "venue": "", "year": 2020 }, { "abstract": "Friction and wear take place on two solid surfaces in sliding contact as a result of the mechanical, thermal, and chemical interactions with the participation of environmental species. These interactions lead to the formation of a tribo layer or tribofilm, which attaches on the worn surfaces, and consequently, contributes to the variation of the friction and wear behaviour. Electron microscopy and the associated spectroscopic analyses are powerful in probing these matters in spatial resolutions from micro to atomic scale. This article provides a review of the author's work in the wear and friction mechanisms of physical vapour deposition (PVD) hard coatings, in which various scanning electron microscope (SEM)and transmission electron microscope (TEM) based microscopic and spectroscopic techniques were employed. Understanding on the failure mechanisms and the origin of self adaptive friction has been improved to the nano scale. Other related issues are also discussed, such as sample preparation techniques for cross sectional electron microscopy, energy dispersive X ray spectroscopy, and electron energy loss spectroscopy.", "author_names": [ "Quanshun Luo" ], "corpus_id": 52085420, "doc_id": "52085420", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Electron Microscopy and Spectroscopy in the Analysis of Friction and Wear Mechanisms", "venue": "", "year": 2018 }, { "abstract": "Friction and wear take place on two solid surfaces in sliding contact as a result of the mechanical, thermal, and chemical interactions with the participation of environmental species. These interactions lead to the formation of a tribo layer or tribofilm, which attaches on the worn surfaces, and consequently, contributes to the variation of the friction and wear behaviour. Electron microscopy and the associated spectroscopic analyses are powerful in probing these matters in spatial resolutions from micro to atomic scale. This article provides a review of the author's work in the wear and friction mechanisms of physical vapour deposition (PVD) hard coatings, in which various scanning electron microscope (SEM) and transmission electron microscope (TEM) based microscopic and spectroscopic techniques were employed. Understanding on the failure mechanisms and the origin of self adaptive friction has been improved to the nano scale. Other related issues are also discussed, such as sample preparation techniques for cross sectional electron microscopy, energy dispersive X ray spectroscopy, and electron energy loss spectroscopy.", "author_names": [ "Quanshun Luo" ], "corpus_id": 116636736, "doc_id": "116636736", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Electron Microscopy and Spectroscopy in the Analysis of Friction and Wear Mechanisms", "venue": "", "year": 2018 }, { "abstract": "The elbow plays a crucial role in changing the flow direction of the medium in pipeline system and is one of the most commonly used pipeline components in the oil and gas transportation. This paper focuses on the corrosive failure mechanism of the elbow of regeneration tower of LPG desulfurization unit in a refinery. Aiming at the failure elbow, based on the macro and micro perspectives, the physical laws of the inner layer of the elbow, including the distribution of corrosion holes and wall thickness, are summarized and analyzed. The further characterization methods were used to study the corrosion mechanism, including mechanical properties, metallographic examination, X ray diffraction analysis (XRD) scanning electron microscopy (SEM) and energy spectrum analysis (EDS) Taking the thief hole as center, the elbow was divided into 4 rows. It is found that the maximum diameter was 21.1 mm while the minimum was 7.76 mm, and the vast majority of holes were 16 19 mm. The average size of the middle section was larger, meanwhile, possessed most holes over 19 mm. The corrosion thickness first increased then decreased along the flow direction and reached the maximum in completely destroyed area of the 1st and 2nd row. The corrosion thickness increased gradually along the flow direction of the 3rd and 4th row. Erosion corrosion is the main cause of elbow failure. Fluid erosion plays a dominant role in the failure process while electrochemical corrosion plays a dominant role in the formation of corrosion holes. Besides, the presence of heat stable salts (HSS) also aggravates the corrosion of elbow.", "author_names": [ "Zou Jianwen", "Shao Guoqing", "Wang Chuan-sheng" ], "corpus_id": 210287660, "doc_id": "210287660", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Corrosion Failure Analysis of Elbow in LPG Desulfurization Unit", "venue": "", "year": 2019 }, { "abstract": "This tutorial will describe the novel technique of using leading edge 3D X Ray Microscopy (XRM) technology to complement physical cross section in Failure Analysis (FA) and 3DIC package development workflows. Contrary to popular believe that \"3D X Ray\" is too slow, we explain how XRM, a new 3D X Ray variant technique differs from conventional 3D X Ray Micro Computed Tomography (MicroCT) and can be optimized to provide non destructive, near SEM imaging of a sample within 10300min throughput time (TPT) depending on its physical properties material composition, critical feature dimensions, and sample size. The specifics of the inspection technique itself and how X rays interact with the sample to achieve high quality images will be discussed. Example images comparing and correlating optical and Scanning Electron Microscope (SEM) images taken from a physical crosssection and a virtual cross section images taken from XRM scans will be shown (Figures 1 and 2)", "author_names": [ "Luke Hunter" ], "corpus_id": 37686039, "doc_id": "37686039", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Non Destructive 3D X Ray Microscopy to Complement Physical Cross Section in the Failure Analysis and Package Development Workflows", "venue": "", "year": 2013 }, { "abstract": "With the development of IC manufacturing industry, plastic encapsulated MOS components have been widely applied. Since higher performance requirement from users, the research on the reliability of plastic encapsulated MOS components is especially important. Through researching the common failure mechanism of plastic encapsulated MOS component, the physical and chemical processes of each failure mechanism are analyzed. In addition, some researches on the relationship among EOS (Electrical Over Stress) EM(Electro migration) and ESD(Electrostatic discharge) have been completed. By study about the methods of failure analysis of plastic encapsulated MOS component, SAM (Scanning Acoustic Microscope) and SEM(Scanning Electron Microscope) are identified as the most important methods in failure analysis. According to the achievement of these researches, the procedure of failure analysis has been optimized by adding microscopy sample preparation. This improvement makes the analysis in chip surface extend to chip section. In the case study, with this new procedure, a plastic encapsulated MOSFET has been analyzed. As a result, this failure is caused by the source drain breakdown. Combining with the mechanism of EOS and EM, the direction of current in PN junction which is breakdown has been identified.", "author_names": [ "Yang Yang", "Liangxue Cai", "Peng Li", "Haotian Lu" ], "corpus_id": 22854739, "doc_id": "22854739", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Failure analysis of plastic encapsulated MOS component from chip section", "venue": "2017 Second International Conference on Reliability Systems Engineering (ICRSE)", "year": 2017 }, { "abstract": "Abstract In the recent years, localization of subtle defects has required device electrical data. Nanoprobing systems based on scanning electron microscopy (SEM) or atomic force microscopy (AFM) have become a significant tool for device measurement in failure analysis (FA) Labs. Failure Analysts can use electrical characteristics to isolate failure location in the metal oxide semiconductor field effect transistor (MOSFET) The missing lightly doped drain (LDD) implant is an example of a critical failure mechanism for the MOSFET and cell in the SRAM which is localized using nanoprobing. In this article, device data analysis and theoretical deductions are discussed related to missing LDD doping. Device data is used to propose a full set of characteristic for missing LDD. The simulation from a mature tool is able to support the electrical characteristics. The capability and challenge of the following physical FA to reveal the defect are also discussed.", "author_names": [ "Li-Lung Lai", "Xiaojing Wu" ], "corpus_id": 2525810, "doc_id": "2525810", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The device characteristics of missing LDD implantation via nanoprobing techniques for localized failure analysis", "venue": "Microelectron. Reliab.", "year": 2015 }, { "abstract": "The automobile power steering pump failure was an accident caused by multiple parts fracture coexistence.Means such as chemical compositions analysis,hardness test,macro and micro analysis,scanning electron microscopy and energy spectrum analysis,as well as other approaches were used to analyze the failure causes of an automobile power steering pump.According to the results obtained from physical testing and chemical analysis,and considering the functions and load capacity of each part when the pump was in operation,it was found out that the blade was the primary fracture part,and the reason for the blade fracture was that there were severe long string shape inclusion defect in the blade.", "author_names": [ "Dunlop Da", "Cnr Grou" ], "corpus_id": 139068132, "doc_id": "139068132", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Failure Analysis on an Automobile Power Steering Pump", "venue": "", "year": 2015 }, { "abstract": "This paper presents an investigation into the reliability and physical degradation mechanisms associated with the loss of battery performance. Cells from two different manufactures underwent cycle life testing until failure (defined as a 20% decrease in nominal capacity) Designated samples from each battery type were subjected to one of two different discharge methods, one at a constant discharge rate of 1C and the other at a constant discharge rate of 0.5C. A third group of batteries were collected and examined after undergoing catastrophic failure in field applications. The tape pull test (to test adhesion/cohesion of electrode material to current collectors) is introduced for the first time in battery literature. Other analysis techniques such as x ray imaging and environmental scanning electron microscopy were used to investigate the structural and chemical degradation of all the samples. Statistical analysis was performed on the cycle life data to evaluate battery reliability.", "author_names": [ "Nicholas Dane Williard", "", "Michael D Osterman", "Michael G Pecht" ], "corpus_id": 7443696, "doc_id": "7443696", "n_citations": 16, "n_key_citations": 1, "score": 0, "title": "Reliability and failure analysis of Lithium Ion batteries for electronic systems", "venue": "2012 13th International Conference on Electronic Packaging Technology High Density Packaging", "year": 2012 } ]

[ { "abstract": "We experimentally investigate delay based photonic reservoir computing using semiconductor lasers with optical feedback and injection. We apply different types of temporal mask signals, such as digital, chaos, and colored noise mask signals, as the weights between the input signal and the virtual nodes in the reservoir. We evaluate the performance of reservoir computing by using a time series prediction task for the different mask signals. The chaos mask signal shows superior performance than that of the digital mask signals. However, similar prediction errors can be achieved for the chaos and colored noise mask signals. Mask signals with larger amplitudes result in better performance for all mask signals in the range of the amplitude accessible in our experiment. The performance of reservoir computing is strongly dependent on the cut off frequency of the colored noise mask signals, which is related to the resonance of the relaxation oscillation frequency of the laser used as the reservoir.", "author_names": [ "Yoma Kuriki", "Joma Nakayama", "Kosuke Takano", "Atsushi Uchida" ], "corpus_id": 4138190, "doc_id": "4138190", "n_citations": 48, "n_key_citations": 1, "score": 1, "title": "Impact of input mask signals on delay based photonic reservoir computing with semiconductor lasers.", "venue": "Optics express", "year": 2018 }, { "abstract": "Abstract With the characteristics of high capital investment and complicated manufacturing processes, effectively planning and analyzing the available capacity is a crucial challenge in semiconductor industry. However, the fab management staffs usually believe that the ideal planned capacity, generated by static capacity planning approach, is too optimistic to achieve, in particular, many abnormal events (e.g. machine breakdown) occurring in fab are not reasonably considered. Therefore, this paper aims at proposing a capacity impact analysis (CIA) approach based on a reasonable capacity plan generated by an object oriented capacity planning simulation system. As such it analyzes the impact of the identified critical available time (AT) fluctuation of machines, the level of AT% and the loading of machine on overall capacity and output performance (e.g. wafer out, utilization, WIP) in a fab. The simulation experiment shows that a capacity performance is highly affected by the machines belonging to a single machine multiple layers (SM) machine group, and the level of AT% (i.e. not the AT fluctuation) Therefore, fab management staff should put more attention on the promised AT or increasing the level of AT% of the \"key\" machines to maintain a high throughput.", "author_names": [ "Li-Chih Wang", "Pei-Chun Chu", "Siying Lin" ], "corpus_id": 115439959, "doc_id": "115439959", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Impact of capacity fluctuation on throughput performance for semiconductor wafer fabrication", "venue": "Robotics and Computer Integrated Manufacturing", "year": 2019 }, { "abstract": "Wafer circuit probing (CP) testing is one of the most important processes for semiconductor manufacturing to ensure the wafers are of good quality. However, the outcomes of CP measurements are not always as good as expected. Engineers take lots of efforts to diagnose CP measurement and classify the features so that make the root cause more evident. In searching the root cause for low yield wafers, gathering the bad wafers and finding their correlation between yields and stages for each process is a common procedure to check whether the stage or the corresponding equipment is the one of the factors that lowers the yield significantly. A system was developed to realize the procedure that defines wafer status and points out the problems that make the yield lower. Once a wafer was inputted into this system, a diagnosis for the wafer will be made automatically. And hence this system was named auto commonality, which means grouping the bad wafers and finding the root cause then making decisions without any manpower.", "author_names": [ "Ji Fu Kung", "Yung Chien Kung", "Jing Pei Lin", "Ming Wei Chen", "Te Hsuan Chen", "Hsiao Ying Yang", "Pei Wen Chen" ], "corpus_id": 215721699, "doc_id": "215721699", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Mining Factors Impact Wafer Circuit Probing Via Neural Network and Statistics for Semiconductor Device Fabrication", "venue": "2019 Joint International Symposium on e Manufacturing Design Collaboration(eMDC) Semiconductor Manufacturing (ISSM)", "year": 2019 }, { "abstract": "P ERCHED AS WE are on the crest of the current tech and computing enrollment boom, it is hard to remember the dark days of the early 2000s. The NASDAQ Index peaked on March 10, 2000, declining almost 80% over the next two years. The stock market crash in the U.S. caused the loss of $5 trillion in the market valuations from 2000 to 2002. Computing enrollments in North America went into a steep dive. At the same time, the Internet enabled the globalization of software production giving rise to the phenomenon of offshore outsourcing. There were daily stories in the media describing major shifts in employment that were occurring largely as a result of software off shoring. Combined with the dot com bust, these reports raised concerns about the future of information technology (IT) as a viable field of study and work in developed countries. In response to these concerns, ACM Council commissioned a Task Force in 2004 to \" look at the facts behind the rapid globalization of IT and the migration of jobs resulting from out sourcing and offshoring. \" The Task Force, co chaired by Frank Mayadas and myself, with the assistance of Wil liam Aspray as Editor, issued its report Globalization and Offshoring of Software in 2006. The report concluded that there is no real reason to believe that IT jobs are migrating away from developed countries. The passing decade has vindicated that conclusion. But while the report conceded that \" trade gains may be distributed differentially \" meaning some individuals gain and some lose, some localities gain and some lose; it was focused narrowly on the IT industry. Had we looked at the broader impact of globalization on the economy, we might have reached somewhat less sanguine conclusions. Globalization exerted tremendous competitive pressure on manufacturing in developed countries. It is instructive to examine the response to this competitive pressure, taking U.S. manufacturing as an example. To survive in the intensely competitive global economy, U.S. manufacturing had to increase its productivity dramatically, substituting technology for labor. U.S. manufacturing productivity roughly doubled between 1995 and 2015. As a result, while U.S. manufacturing output today is essentially at an all time high, employment peaked around 1980, and has been declining precipitously since 1995. Neoclassical economists argue that when technology destroys jobs \" people find other jobs, albeit possibly after a long period of painful adjustment. \" They are definitely right about the painful", "author_names": [ "Moshe Y Vardi" ], "corpus_id": 8325949, "doc_id": "8325949", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Globalization, computing, and their political impact", "venue": "Commun. ACM", "year": 2016 }, { "abstract": "The use of social media platforms in political campaigns has widely been studied. Many scholars have provided evidence about the impact of Twitter, Facebook and YouTube. So far; some of them have argued on the uselessness of these technologies about changing vote decisions, candidates' perception or political information efficacy. Most recently, the sentiment analysis has provided new paths to understand the link between the social media technology and voters. This paper analyzes data collected from Facebook's posts (4128 posts) and their emoticons love, hate, anger, likes, etc. that reveals some kind of sentiment from the users in a local government campaign in the central State of Mexico, which took place in June 2017. Findings show that political parties have a large impact with few posts, but in general, this paper reveals that voters' perception of candidates in Facebook is bad for the winner political party, since despite of this situation, the political party with the best sentiment impact, could not win the elections.", "author_names": [ "Rodrigo Sandoval-Almazan", "David Valle Cruz" ], "corpus_id": 195348601, "doc_id": "195348601", "n_citations": 19, "n_key_citations": 1, "score": 0, "title": "Facebook impact and sentiment analysis on political campaigns", "venue": "DG.O", "year": 2018 }, { "abstract": "Semiconductor manufacturing (fab) is a highly complex, cost intensive and competitive industry. For a fab, batch factor for furnace tools is a key fab performance metric for capacity and cycle time assessment. Batch production is one of the manufacturing methods where, a group of wafers can be processed together in a batch in a given timeframe. Furnace tools have the ability to batch the wafers together. In this paper, we propose to establish the relationship between batch factor and cycle time to calculate the optimal batch factor within the permissible limits of cycle time. Most furnace tools need to wait for the same kind of wafers to improve its batch factor. Thus, to achieve large batch factor, the cycle time of the WIP at these furnace tools inadvertently becomes high. This creates a need to know how high batch factor can increase without adversely affecting the cycle time and help in making optimized batching decisions.", "author_names": [ "Nivedha Rajasekaran", "Vikram Arjunwadkar", "Richard Man" ], "corpus_id": 221568074, "doc_id": "221568074", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Empirical Relationship between Cycle time Impact and Batching on Furnaces in Semiconductor Foundry", "venue": "2020 31st Annual SEMI Advanced Semiconductor Manufacturing Conference (ASMC)", "year": 2020 }, { "abstract": "Citizens' perception of politicians and political issues is increasingly influenced by social media. However, little is known about the potential of second order effects of social media in parts of the world where the majority of voting citizens are not online. In this paper, we examine whether a politician can move to communicating through social media as their primary means of outreach, and still present their message to the mainstream population through traditional media. By studying of the use of Twitter by Indian Prime Minister Narendra Modi between 2009 and 2015, the second most followed elected official in the world, we present evidence of the impact of social media on print news. We use computational text mining techniques to automatically identify print news reports that use Modi's tweets as a source, alongside manual qualitative coding of tweets to analyze the role of tweet themes in print news coverage. We conclude that while Modi's social media messaging does get coverage in the print news, it is his more \"newsworthy\" tweets, such as references to celebrities, other politicians, or major events such as holidays that have a greater likelihood of coverage.", "author_names": [ "Sunandan Chakraborty", "Joyojeet Pal", "Priyank Chandra", "Daniel M Romero" ], "corpus_id": 49347357, "doc_id": "49347357", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Political Tweets and Mainstream News Impact in India: A Mixed Methods Investigation into Political Outreach", "venue": "COMPASS", "year": 2018 }, { "abstract": "We studied the topical preferences of social media campaigns of India's two main political parties by examining the tweets of 7382 politicians during the key phase of campaigning between Jan May of 2019 in the run up to the 2019 general election. First, we compare the use of self promotion and opponent attack, and their respective success online by categorizing 1208 most commonly used hashtags accordingly into the two categories. Second, we classify the tweets applying a qualitative typology to hashtags on the subjects of nationalism, corruption, religion and development. We find that the ruling BJP tended to promote itself over attacking the opposition whereas the main challenger INC was more likely to attack than promote itself. Moreover, while the INC gets more retweets on average, the BJP dominates Twitter's trends by flooding the online space with large numbers of tweets. We consider the implications of our findings hold for political communication strategies in democracies across the world.", "author_names": [ "Anmol Panda", "Ramaravind Kommiya Mothilal", "Monojit Choudhury", "Kalika Bali", "Joyojeet Pal" ], "corpus_id": 218982480, "doc_id": "218982480", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Topical Focus of Political Campaigns and its Impact: Findings from Politicians' Hashtag Use during the 2019 Indian Elections", "venue": "Proc. ACM Hum. Comput. Interact.", "year": 2020 }, { "abstract": "Integrating uses and gratifications theory and the cognitive/communication mediation model: this study examines Chinese students' use of social media and subsequent impact on political participation. An integrative framework is proposed where media use, political expression, and political cognitions (efficacy and knowledge) play important mediating roles between audience motivations and participation. Structural equation analyses showed support for the integrated model. Guidance and social utility motivations exhibited different indirect effects on online and offline participation through social media news, discussion, and political efficacy. Entertainment motivations exhibited no direct or indirect effects. Contrary to expectations and previous literature, surveillance motivations exhibited negative direct and indirect effects on offline participation, which may be attributed to the particular Chinese social and political context. Implications of the findings are discussed.", "author_names": [ "Zhuo Chen", "Michael Chan" ], "corpus_id": 33260473, "doc_id": "33260473", "n_citations": 17, "n_key_citations": 2, "score": 0, "title": "Motivations for Social Media Use and Impact on Political Participation in China: A Cognitive and Communication Mediation Approach", "venue": "Cyberpsychology Behav. Soc. Netw.", "year": 2017 }, { "abstract": "We consider the problem of managing output in semiconductor wafer fabrication facilities when a new product is introduced alongside a current product. We propose a mathematical model of the impact of the new product on the distribution of the effective processing time, and use a simple Excel simulation to illustrate the impact of different release control policies on output under product transitions.", "author_names": [ "Atchyuta Bharadwaj Manda", "Reha Uzsoy", "Karl G Kempf", "Sukgon Kim" ], "corpus_id": 12230194, "doc_id": "12230194", "n_citations": 9, "n_key_citations": 2, "score": 0, "title": "Modeling the impact of new product introduction on the output of semiconductor wafer fabrication facilities", "venue": "2016 Winter Simulation Conference (WSC)", "year": 2016 } ]

[ { "abstract": "In high performance magnetic resonance imaging systems, the gradient driver is required to supply the gradient coil with a large current >600 A) and a high voltage >2000 V) to achieve a strong gradient field and a fast slew rate. In addition, extremely high fidelity for reproducing the current command from the central system is very critical to imaging quality. This paper presents the solutions for the different elements of the driver: 1) high bandwidth (BW) power inverter; 2) ripple cancelation filter; 3) multioutput power supply (PS) and 4) digital control. A high BW power inverter requires a stacked bridges structure to achieve a high output ripple frequency with the existing commercial power semiconductor modules. The high voltage and the high frequency for large power modules can be obtained easier and with lower loss using the new silicon carbide devices. The control needs a digital implementation and a very fast processor. Digital control provides compensation and feedforward to improve the response. A capability improvement is obtained by reducing the switching frequency when large currents with a very low frequency variation are needed. The control can handle it very well, but the filter has to be designed to eliminate more than one ripple frequency. Finally, many PS solutions have been used for multiple isolated outputs, but digital control compensation permits the use of much simpler unregulated PS and keeps the performance. A 2 MVA, 900 A/1200 V, platform has been built and fully tested. The experimental results proved the validity of the proposed structure and the modulation technique.", "author_names": [ "J A Sabate", "Ruxi Rudy Wang", "Fengfeng Tao", "Song Chi" ], "corpus_id": 26124717, "doc_id": "26124717", "n_citations": 18, "n_key_citations": 0, "score": 1, "title": "Magnetic Resonance Imaging Power: High Performance MVA Gradient Drivers", "venue": "IEEE Journal of Emerging and Selected Topics in Power Electronics", "year": 2016 }, { "abstract": "A high power, high efficiency switching amplifier capable of generating arbitrary gradient coil waveforms for a magnetic resonance imaging system is described. A high frequency \"partial voltage\" buck regulator feeds a \"full voltage\" full bridge inverter to relieve the full bridge of the necessity of switching when high voltage is needed by the load. When high voltage is needed, the partial voltage buck circuit that employs faster lower voltage IGBT devices assumes the switching duty. When low voltage is needed, the high voltage bridge inverter, operating from a low voltage DC bus, assumes the switching duty. Since switching losses are approximately proportional to bridge input voltage, the switching losses incurred by the inverter are minimized.", "author_names": [ "Robert Steigerwald", "William Frederick Wirth" ], "corpus_id": 109670178, "doc_id": "109670178", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "High power, high performance switching amplifier for driving magnetic resonance imaging gradient coils", "venue": "2000 IEEE 31st Annual Power Electronics Specialists Conference. Conference Proceedings (Cat. No.00CH37018)", "year": 2000 }, { "abstract": "Access to scanners for magnetic resonance imaging (MRI) is typically limited by cost and by infrastructure requirements. Here, we report the design and testing of a portable prototype scanner for brain MRI that uses a compact and lightweight permanent rare earth magnet with a built in readout field gradient. The 122 kg low field (80 mT) magnet has a Halbach cylinder design that results in a minimal stray field and requires neither cryogenics nor external power. The built in magnetic field gradient reduces the reliance on high power gradient drivers, lowering the overall requirements for power and cooling, and reducing acoustic noise. Imperfections in the encoding fields are mitigated with a generalized iterative image reconstruction technique that leverages previous characterization of the field patterns. In healthy adult volunteers, the scanner can generate T1 weighted, T2 weighted and proton density weighted brain images with a spatial resolution of 2.2 x 1.3 x 6.8 mm3. Future versions of the scanner could improve the accessibility of brain MRI at the point of care, particularly for critically ill patients.", "author_names": [ "Clarissa Zimmerman Cooley", "Patrick C McDaniel", "Jason P Stockmann", "Sai Abitha Srinivas", "Stephen F Cauley", "Monika Sliwiak", "Charlotte R Sappo", "Christopher F Vaughn", "Bastien Guerin", "Matthew S Rosen", "Michael H Lev", "Lawrence L Wald" ], "corpus_id": 227158296, "doc_id": "227158296", "n_citations": 11, "n_key_citations": 2, "score": 0, "title": "A portable scanner for magnetic resonance imaging of the brain.", "venue": "Nature biomedical engineering", "year": 2020 }, { "abstract": "As radiologists demand increased power, speed, and duty cycle from their magnetic resonance imaging (MRI) systems, thermal management of the gradient driver sub system becomes more challenging. MRI systems contain three IGBT based gradient drivers that apply current waveforms to an inductive load located inside a cylindrical magnet. The effectiveness of the gradient driver cooling system determines the power, speed, and duty cycle of the MRI system. MRI gradient drivers are unique in the world of power electronics in that they must be able to generate arbitrary current waveforms with extremely high fidelity. This high fidelity requirement means that the IGBTs must switch at frequencies greater than >10 kHz, resulting in die level heat fluxes approaching 100W/cm2, dictating the use of liquid cooling. The gradient driver cooling system design is further challenged by a continuing loss of die level thermal time constant as IGBT manufacturers incorporate thinner die with each new generation of IGBTs. The loss of die level thermal time constant results in higher IGBT junction temperature excursions, placing more demands on cold plate performance. Numerous experiments were performed to characterize IGBT switching losses and transient thermal behavior. The data was used to create an electrical/thermal model to predict heat generation, junction temperature rise, and reliability. Monte Carlo simulations were performed on the electrical/thermal model to assess the impact of variations in IGBT manufacturing, cooling system performance, and scan sequences in order to derive requirements for a cold plate design. Cold plate performance was experimentally verified and the design was deemed robust, or insensitive to sources of variation", "author_names": [ "G K Morris", "J A Galie" ], "corpus_id": 1527474, "doc_id": "1527474", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Design of a robust cold plate for high power gradient drivers in magnetic resonance imaging systems", "venue": "Thermal and Thermomechanical Proceedings 10th Intersociety Conference on Phenomena in Electronics Systems, 2006. ITHERM 2006.", "year": 2006 }, { "abstract": "In high performance magnetic resonance imaging (MRI) systems, the gradient driver is required to supply the gradient coil with large amplitude >600A) and high slew rate >2A/us) current waveform. In addition, extremely high fidelity for reproducing the current command from the central system is very critical for imaging quality. This paper presents an improved gradient driver structure and a new modulation scheme, with which the switching frequency will vary according to the slew rate of the current command. The corresponding output filter design is also introduced. With the proposed technique the switching loss can be reduced and evenly distributed in all the bridges, therefore the utilization ratio of the semiconductor devices is improved and the number of devices in parallel can be reduced. A 2 MVA platform has been built and fully tested. The experimental results proved the validity of the proposed structure and modulation technique.", "author_names": [ "Rixin Lai", "J A Sabate", "Song Chi", "Wesley M Skeffington" ], "corpus_id": 45645310, "doc_id": "45645310", "n_citations": 18, "n_key_citations": 1, "score": 0, "title": "High performance gradient driver for magnetic resonance imaging system", "venue": "2011 IEEE Energy Conversion Congress and Exposition", "year": 2011 }, { "abstract": "This paper presents a magnetic resonance imaging gradient amplifier power supply with a series resonant converter (SRC) using an innovative optimal phase shift control. This provides very fast response by eliminating the dynamics associated with the resonant tank. One phase leg has zero voltage switching; the other leg has both zero voltage and zero current switching. This ensures very low switching losses. The switched gradient amplifier load presents specific challenges: multiple outputs with good cross regulation, and very fast load transient response. All load currents vary independently from no load to full load, and output voltages must be tightly regulated for all conditions. The solution presented uses post regulators for half of the output voltages. Several post regulator options are compared based on performance and reliability. The proposed approach has high power density and excellent performance.", "author_names": [ "J A Sabate", "Michael Joseph Schutten", "Qiming Li", "William Frederick Wirth" ], "corpus_id": 109570646, "doc_id": "109570646", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Resonant power supply for magnetic resonance imaging gradient drivers", "venue": "IEEE 34th Annual Conference on Power Electronics Specialist, 2003. PESC '03.", "year": 2003 }, { "abstract": "The magnetic resonance imaging (MRI) gradient driver is a high performance inverter that provides large currents, >1000A, for the gradient magnetic fields used for imaging. It is challenging to achieve the required performance with the fast transitions on current pulses driven with high voltages, >2000V, for fast imaging. The currents provided by the driver are defined by the imaging procedure and are always changing from zero to maximum current, resulting on pulsating load from zero load to 10 times the rated power. The accuracy for the currents supplied to the gradient coils requires regulated voltages provided to the inverter not to sag below 10% of rated value. To avoid voltage sag and to limit peak power draw from the facility power utilities, the system has capacitors for energy storage at the inverter supply voltages and at the input of the power supplies for the inverter. The paper presents the power architecture for power supplies, inverter (gradient amplifier) and energy storage, and how the energy storage is optimized to avoid excessive demands on facility power feed that have to be designed for peak power. The architecture and energy storage selections reduced the input current and minimized the voltage sagging at the inverter input. The solution was implemented, and the results are presented here when operating standard imaging sequences.", "author_names": [ "Yash Veer Singh", "J A Sabate", "Ruxi Rudy Wang" ], "corpus_id": 169031915, "doc_id": "169031915", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Capacitive Energy Storage for Magnetic Resonant Imaging Gradient Driver", "venue": "2019 IEEE Applied Power Electronics Conference and Exposition (APEC)", "year": 2019 }, { "abstract": "Gradient coils for magnetic resonance imaging (MRI) require large currents 500 A) for the gradient field strength, as well as high voltage 1600 V) for fast slew rates. Additionally, extremely high fidelity, reproducing the command signal, is critical for image quality. A new driver topology recently proposed can provide the high power and operate at high switching frequency allowing high bandwidth control. The paper presents additional improvements to the new driver architecture, and more importantly, describes the digital control design and implementation, crucial to achieve the required performance level. The power stage and control have been build and tested with the experimental results showing that the performance achieved with the new digital control capability, more than fulfills the system requirements", "author_names": [ "J A Sabate", "Luis Garces", "Paul Michael Szczesny", "Qiming Li", "William Frederick Wirth" ], "corpus_id": 13589195, "doc_id": "13589195", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "High bandwidth high power gradient driver for magnetic resonance imaging with digital control", "venue": "Twentieth Annual IEEE Applied Power Electronics Conference and Exposition, 2005. APEC 2005.", "year": 2005 }, { "abstract": "A switch mode gradient amplifier based on dual parallel H bridge topology was presented.Dynamic dead time control method was proposed to reduce the reverse recovery current of power MOSFET.The output filter was designed and optimized for both common and differential mode with good damping and small losses.Further a high performance current tracking controller,combing with state feedback,feed forward and nonlinear PI regulations,was proposed based on the decoupling of common and differential mode of the gradient amplifier model.To ease the requirements of sampling system,a simple PI controller was applied instead of the tracking controller during the steady period.Finally,a dual DSP control system was designed to implement the control algorithm,and a 200 A/150 V gradient amplifier was built in the laboratory.Experimental results show that only 1% overshoot occurs when tracking a trapezium current with 200 A amplitude and 200 ms rising time;the low frequency noise is in the order of mA when outputing DC current.", "author_names": [ "Jiang Xiaohua" ], "corpus_id": 113349700, "doc_id": "113349700", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Digital Controlled Gradient Amplifier for Magnetic Resonance Imaging", "venue": "", "year": 2010 }, { "abstract": "In Magnetic Resonance Imaging system, the most powerful device is gradient driver, which is also one of the key components to realize fast imaging with high quality. To meet the requirements of high end MRI products, the power rating of the gradient driver increase from several hundred kVA to 1MVA and even higher in the future. Commonly the gradient driver applies full bridge cascade technology and needs a lot isolated DC source with high power capability. To provide solution to this requirement, several technology platforms have been developed. This paper presents one of the most attractive options. In the proposed power supply structure, an AC pre regulator and a multi winding transformer are combined together with diode rectifiers to provide multiple isolated DC outputs. The AC pre regulator compensates the utility voltage variation by injecting voltage to the input line through a series transformer, and that make the multi winding transformer get a stable input. With this solution, the DC outputs voltage is only determined by the transformer leakage inductance and load current. Compared with high frequency DC DC conversion methods, this scheme does not need high frequency magnetic devices and capacitors, which are difficult to build and high cost for high power application. The switching devices (IGBTs) in this option can also operate at a much lower frequency (several kHz) to reduce the switching loss, and lower switching frequency also benefit the device selection. Beside that the rectifiers applied at the secondaries of the multi winding transformer operate at line frequency and that benefits the device selection and cost too. Here in this paper, the control algorithm of the power supply is presented and discussed. Both its self performance and co operation with the amplifier are evaluated with Saber simulation. The results indicate the attractiveness of the proposed scheme.", "author_names": [ "Pengcheng Zhu", "Yunfeng Liu", "J A Sabate" ], "corpus_id": 43122006, "doc_id": "43122006", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Multi output power supply with series voltage compensation capability for Magnetic Resonance Imaging system", "venue": "2009 IEEE 6th International Power Electronics and Motion Control Conference", "year": 2009 } ]

[ { "abstract": "Electrolyte layer, made up of an ionic conductor with ignorable electronic conductivity, plays vital roles in transporting ions as well as blocking electron passage in electrochemical devices like a solid oxide fuel cell (SOFC) The electronic conductivity of the electrolyte has been always blamed for bringing in the short circuiting problem. In this study, however, we demonstrate that the dominant issue is not the electronic conductivity of electrolytes but the energy band diagram of the device. Using a semiconductor TiO2 thin film as an electrolyte, we present a novel design of fuel cell devices from the perspective of the energy band structure and alignment. A TiO2 thin film was fabricated by a mass productive spin coating method. An OCV of 1.1 V and maximum power output of 364 mW cm 2 at 550 degC were achieved, which proves that TiO2 plays the role of an electrolyte with sufficient ionic transportation while no electronic short circuiting problem occurs. The online intercalation of Li into TiO2 enables the creation of more oxygen vacancies. Additionally, proton incorporation and conducting mechanisms in TiO2 have been verified and discussed. This work provides a new method for suppressing the electronic conductivity of electrolytes as well as developing functional electrolytes from a well known semiconductor for advanced low temperature SOFCs.", "author_names": [ "Wenjing Dong", "Yuzhu Tong", "Bin Zhu", "Haibo Xiao", "Lili Wei", "Chaoyu Huang", "Baoyuan Wang", "Xunying Wang", "Jung-Sik Kim", "Haixia Wang" ], "corpus_id": 198328025, "doc_id": "198328025", "n_citations": 30, "n_key_citations": 0, "score": 1, "title": "Semiconductor TiO2 thin film as an electrolyte for fuel cells", "venue": "", "year": 2019 }, { "abstract": "This is the first time we report that simply air plasma treatment can also enhances the optical absorbance and absorption region of titanium oxide (TiO2) films, while keeping them transparent. TiO2 thin films having moderate doping of Fe and Co exhibit significant enhancement in the aforementioned optical properties upon air plasma treatment. The moderate doping could facilitate the formation of charge trap centers or avoid the formation of charge recombination centers. Variation in surface species viz. Ti3+ Ti4+ O2 oxygen vacancies, OH group and optical properties was studied using X ray photon spectroscopy (XPS) and UV Vis spectroscopy. The air plasma treatment caused enhanced optical absorbance and optical absorption region as revealed by the formation of Ti3+ and oxygen vacancies in the band gap of TiO2 films. The samples were treated in plasma with varying treatment time from 0 to 60 seconds. With the increasing treatment time, Ti3+ and oxygen vacancies increased in the Fe and Co doped TiO2 films leading to increased absorbance; however, the increase in optical absorption region/red shift (from 3.22 to 3.00 eV) was observed in Fe doped TiO2 films, on the contrary Co doped TiO2 films exhibited blue shift (from 3.36 to 3.62 eV) due to Burstein Moss shift.", "author_names": [ "Bandna Bharti", "Santosh Kumar", "Heung-no Lee", "Rajesh Kumar" ], "corpus_id": 9354884, "doc_id": "9354884", "n_citations": 474, "n_key_citations": 5, "score": 0, "title": "Formation of oxygen vacancies and Ti3+ state in TiO2 thin film and enhanced optical properties by air plasma treatment", "venue": "Scientific reports", "year": 2016 }, { "abstract": "Graphene oxide platelets synthesized by using a chemical exfoliation method were deposited on anatase TiO2 thin films. Postannealing of the graphene oxide/TiO2 thin films at 400 degC in air resulted in partial formation of a Ti C bond between the platelets and their beneath thin film. By using atomic force microscopy and X ray photoelectron spectroscopy analyses, UV visible light induced photocatalytic reduction of the graphene oxide platelets of the annealed graphene oxide/TiO2 thin films immersed in ethanol was studied for the different irradiation times. After 4 h of photocatalytic reduction, the vertical space between the platelets decreased from about 1.1 to less than 0.8 nm and the concentration of the C O bond was reduced 85% indicating effective reduction of the graphene oxide platelets to the graphene ones. The graphene oxide/TiO2 thin films reduced at different irradiation times were utilized as nanocomposite photocatalysts for degradation of E. coli bacteria in an aqueous solution under solar li.", "author_names": [ "Omid Akhavan", "Elham Ghaderi" ], "corpus_id": 95198859, "doc_id": "95198859", "n_citations": 765, "n_key_citations": 5, "score": 1, "title": "Photocatalytic Reduction of Graphene Oxide Nanosheets on TiO2 Thin Film for Photoinactivation of Bacteria in Solar Light Irradiation", "venue": "", "year": 2009 }, { "abstract": "In the present study, a selectively exposed (101) crystal facet engineered TiO2 photoanode is investigated for the higher efficiency of the hydrogen evolution reaction. To date, even though the photoelectrochemical performance (PEC) dependent on exposed crystal facets has been calculated and demonstrated in semiconducting microcrystals, selectively exposed crystal facets of photocatalyst thin films have not been reported yet. Herein, we demonstrate a TiO2 thin film photoanode with 100% exclusively exposed crystal facets and suggest a methodology to obtain metal oxide thin film photoanodes with selectively exposed crystal facets. A selectively exposed crystal facet manipulated metal oxide thin film photoanode is fabricated over pre synthesized microcrystals through a three step strategy: (1) hydrothermal synthesis of microcrystals, (2) positioning of microcrystals via polymer induced manual assembly, and (3) fabrication of selectively exposed crystal facets of a TiO2 thin film through a secondary growth hydrothermal reaction. Based on the synthesis of representative TiO2 microcrystals with dominantly exposed (101) (100) and (001) crystal facets, the selectively exposed crystal faceted TiO2 thin film photoanode is comparatively investigated for practical PEC performance. The photocurrent density of the selectively exposed (101) crystal faceted TiO2 thin film photoanode is determined as 0.13 mA cm 2 and has an 18% conversion efficiency of incident photon to current at a 0.65 V Ag/AgCl potential under AM 1.5G illumination. Its photoelectrochemical hydrogen production reached 0.07 mmol cm 2 for 12 h, which is higher than those of (100) and (001) faceted photoelectrodes.", "author_names": [ "Chang Woo Kim", "So-Jin Yeob", "Hui-Ming Cheng", "Young Soo Kang" ], "corpus_id": 93390578, "doc_id": "93390578", "n_citations": 63, "n_key_citations": 1, "score": 0, "title": "A selectively exposed crystal facet engineered TiO2 thin film photoanode for the higher performance of the photoelectrochemical water splitting reaction", "venue": "", "year": 2015 }, { "abstract": "TiO2 thin film based, chemiresistive sensors for NO2 gas which operate at room temperature under ultraviolet (UV) illumination have been demonstrated in this work. The rf sputter deposited and post annealed TiO2 thin films have been characterized by atomic force microscopy, X ray photoelectron spectroscopy, and X ray diffraction to obtain surface morphology, chemical state, and crystal structure, respectively. UV vis absorption spectroscopy and Tauc plots show the optical properties of the TiO2 films. Under UV illumination, the NO2 sensing performance of the TiO2 films shows a reversible change in resistance at room temperature. The observed change in electrical resistivity can be explained by the modulation of surface adsorbed oxygen. This work is the first demonstration of a facile TiO2 sensor for NO2 analyte that operates at room temperature under UV illumination.", "author_names": [ "Ting Xie", "Nichole F Sullivan", "Kristen Lisa Steffens", "Baomei Wen", "Guannan Liu", "Ratan K Debnath", "Albert V Davydov", "Romel D Gomez", "Abhishek Motayed" ], "corpus_id": 4657270, "doc_id": "4657270", "n_citations": 58, "n_key_citations": 2, "score": 0, "title": "UV assisted room temperature chemiresistive NO2 sensor based on TiO2 thin film.", "venue": "Journal of alloys and compounds", "year": 2015 }, { "abstract": "To examine the special features of the antibacterial effect for a thin transparent titanium dioxide (TiO2) film, the photocatalytic degradation of endotoxin, which is a pyrogenic constituent of Escherichia coli (E. coli) as well as its bactericidal activity, was investigated. The TiO2 films were prepared from titanium isopropoxide solution, annealing at 500 degC. The bactericidal activity for E. coli cells was estimated by survival ratio calculated from the number of viable cells which form colonies on the nutrient agar plates. The endotoxin concentration was determined by the Limulus tests. When E. coli cells were killed by the TiO2 photocatalyst under UV irradiation, the endotoxin from the cells was also degraded efficiently. This result shows that the TiO2 photocatalyst has both bactericidal activity and decomposing activity for the endotoxin (i.e. detoxifying activity) The bactericidal effect of the TiO2 thin film results from both inactivating the viability of the bacteria and the destruction of the.", "author_names": [ "Kayano Sunada", "Yoshihiko Kikuchi", "+ and Kazuhito Hashimoto", "Akira Fujishima" ], "corpus_id": 94721490, "doc_id": "94721490", "n_citations": 737, "n_key_citations": 14, "score": 0, "title": "Bactericidal and Detoxification Effects of TiO2 Thin Film Photocatalysts", "venue": "", "year": 1998 }, { "abstract": "We develop a simple approach to fabricate graphene loaded TiO(2) thin films on glass substrates by the spin coating technique. Our graphene loaded TiO(2) films were highly conductive and transparent and showed enhanced photocatalytic activities. More significantly, graphene/TiO(2) films displayed superhydrophilicity within a short time even under a white fluorescent light bulb, as compared to a pure TiO(2) film. The enhanced photocatalytic activity of graphene/TiO(2) films is attributed to its efficient charge separation, owing to electrons injection from the conduction band of TiO(2) to graphene. The electroconductivity of the graphene loaded TiO(2) thin film also contributes to the self cleaning function by its antifouling effect against particulate contaminants. The present study reveals the ability of graphene as a low cost cocatalyst instead of expensive noble metals (Pt, Pd) and further shows its capability for the application of self cleaning coatings with transparency. The promising characteristics of (inexpensive, transparent, conductive, superhydrophilic, and highly photocatalytically active) graphene loaded TiO(2) films may have the potential use in various indoor applications.", "author_names": [ "Srinivasan Anandan", "Tata Narasinga Rao", "Marappan Sathish", "Dinesh Rangappa", "Itaru Honma", "Masahiro Miyauchi" ], "corpus_id": 19209292, "doc_id": "19209292", "n_citations": 181, "n_key_citations": 1, "score": 0, "title": "Superhydrophilic graphene loaded TiO2 thin film for self cleaning applications.", "venue": "ACS applied materials interfaces", "year": 2013 }, { "abstract": "Flat anatase TiO2 thin film deposited at room temperature shows the natural hydrophobicity, which is destroyed by 400 degC vacuum annealing. On the basis of the analysis of surface composition and structure, the origin of hydrophobicity of the flat TiO2 film can be identified as (1) approximately fully stoichiometric TiO2 and (2) hydrocarbon adsorbates on the film surface. We further validate that interfacial water molecules near the surface of the as prepared TiO2 film are oriented in the hydrophobic hydration structure via Fourier transform infrared/attenuated total reflection. Moreover, the as prepared TiO2 film also shows a smart surface reversibly switched between hydrophobicity and super hydrophilicity. During the recovery process of hydrophobicity, the irradiated films show the wettability with water contact angle of 107 1.7, 72 2.5, 80 1.1, and 17 1.3deg corresponding to after a week of exposure to ambient air, O2, CF4, and Ar, respectively. It can be strongly reinforced that the stoichiometry and the adsorbates both play an important role in forming the hydrophobic TiO2 films.", "author_names": [ "Jianzha Zheng", "Shanhu Bao", "Yu Guo", "Ping Jin" ], "corpus_id": 2691612, "doc_id": "2691612", "n_citations": 50, "n_key_citations": 0, "score": 0, "title": "Natural hydrophobicity and reversible wettability conversion of flat anatase TiO2 thin film.", "venue": "ACS applied materials interfaces", "year": 2014 }, { "abstract": "Titanium dioxide (TiO2) has been widely used in the photodegradation of organic contaminants and wastewater treatment in recent years. However, the mechanism of photocatalytic reaction on TiO2 surfaces is still poorly understood, especially for the reactions under real environmental conditions. In the present study, the sum frequency generation vibrational spectroscopy, a surface specific tool, has been employed to in situ study the dissociation and photooxidation reaction of CH3OH on TiO2 thin film, which served as a model system of photooxidizing organic compounds. The experimental results show that mixing O2 with CH3OH promotes more CH3OH dissociation to produce CH3O, and UV light can not only induce CH3OH dissociation to CH3O but also generate large nonresonance. To mimic the photodegradation process of organics, removing methoxy on the TiO2 thin film has been investigated under both aerobic and anaerobic conditions. We have observed two types of methoxy, photocatalytically reactive under both conditi.", "author_names": [ "Ran-ran Feng", "Anan Liu", "Shuo Liu", "Jiao-jian Shi", "Ruidan Zhang", "Zefeng Ren" ], "corpus_id": 101850198, "doc_id": "101850198", "n_citations": 25, "n_key_citations": 0, "score": 0, "title": "In Situ Studies on the Dissociation and Photocatalytic Reactions of CH3OH on TiO2 Thin Film by Sum Frequency Generation Vibrational Spectroscopy", "venue": "", "year": 2015 }, { "abstract": "Abstract Single phase rutile type TiO2 thin films with a high refractive index (n) and a low extinction coefficient (k) prepared on glass are expected to improve the performance of anti reflection coatings. In this study, TiO2 thin films were prepared by the pulsed laser deposition (PLD) method at temperatures ranging from room temperature to 600 degC under an oxygen partial pressure of 1 9 Pa or a 10 5 Pa vacuum, and their crystal structure, microstructure and optical properties were investigated. A single phase rutile type TiO2 thin film was successfully prepared on a glass substrate by depositing at room temperature in a vacuum followed by post annealing at 450 degC in air. A nanocrystalline oxygen deficient phase in the as deposited films plays an important role in the formation of the single rutile phase during post annealing. The single phase rutile type TiO2 thin films showed excellent optical properties, with n 3.14 and k", "author_names": [ "Akihiro Ishii", "Yoko Nakamura", "Itaru Oikawa", "Atsunori Kamegawa", "Hitoshi Takamura" ], "corpus_id": 94103349, "doc_id": "94103349", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "Low temperature preparation of high n TiO2 thin film on glass by pulsed laser deposition", "venue": "", "year": 2015 } ]

[ { "abstract": "High resolution spectroscopy not only can identify atoms and molecules but also can provide detailed information on their chemical and physical environment and relative motion. In the terahertz frequency region of the electromagnetic spectrum, where many molecules have fundamental vibrational modes, there is a lack of powerful sources with narrow linewidths that can be used for absorption measurements or as local oscillators in heterodyne detectors. The most promising solid state source is the THz frequency quantum cascade laser (QCL) however, the linewidth of this compact semiconductor laser is typically too broad for many applications, and its frequency is not directly referenced to primary frequency standards. In this work, we injection lock a QCL operating at 2 THz to a compact fiber based telecommunications wavelength frequency comb, where the comb line spacing is referenced to a microwave frequency reference. This results in the QCL frequency locking to an integer harmonic of the microwave reference, and the QCL linewidth reducing to the multiplied linewidth of the microwave reference, <100 Hz. Furthermore, we perform phase resolved detection of the locked QCL and measure the phase noise of the locked system to be 75 dBc/Hz at 10 kHz offset from the 2 THz carrier.", "author_names": [ "Joshua R Freeman", "Lalitha Ponnampalam", "Haymen Shams", "Reshma A Mohandas", "Cyril C Renaud", "Paul Dean", "Lihang Li", "Alexander Giles Davies", "Alwyn J Seeds", "Edmund H Linfield" ], "corpus_id": 113406014, "doc_id": "113406014", "n_citations": 11, "n_key_citations": 0, "score": 1, "title": "Injection locking of a terahertz quantum cascade laser to a telecommunications wavelength frequency comb", "venue": "", "year": 2017 }, { "abstract": "Quantum Cascade lasers (QCLs) relying on intersubband transitions in semiconductor quantum well structures, show very short carrier lifetimes of the order of picoseconds [1] As a consequence, relaxation oscillations remain over damped up to modulation frequencies of several tens of GHz [2] enabling efficient amplitude modulation of the gain medium in this frequency range. These properties make QCLs ideally suited for RF injection locking. We demonstrate that the round trip frequency of THz QCLs, as observed from the beatnote, can be injection locked by RF modulating the bias current. Within a certain locking range we observe mutual phase locking of approximately 20 longitudinal modes for significantly lower RF powers than in previous studies [3] Apart from injection locking, we demonstrate beatnote control by means of an external cavity.", "author_names": [ "P Taeschler", "Andres Forrer", "David Stark", "T Olariu", "Mattias Beck", "Jerome Faist", "Giacomo Scalari" ], "corpus_id": 204821260, "doc_id": "204821260", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Low RF Power Injection Locking and Beatnote Control of Terahertz Quantum Cascade Laser Frequency Combs", "venue": "2019 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)", "year": 2019 }, { "abstract": "Absolute frequency and phase control of a coherent terahertz (THz) source is desirable for high resolution spectroscopy of atoms and molecules, coherent communications and advanced imaging techniques. Here we report on the phase control of a 2.0 THz quantum cascade laser (QCL) The QCL is optical injection locked (OIL) to an infrared frequency comb, which is generated by the successive modulation of a 'C band' laser in a recirculating fibre loop. A stable microwave source defines the spacing between the comb lines resulting in the QCL being locked to an integer harmonic of the microwave frequency; the reference frequency. Within the locking range the frequency of the injection locked QCL is locked to the reference frequency, whereas the phase of the QCL undergoes a 'p' phase shift across the locking range. In this work, we control the phase of the QCL by introducing a phase lock loop to the OIL system to provide feedback to the QCL current forming an optical injection phase locked loop. This has several advantages over the bare OIL system: (1) the underlying frequency of the QCL is stabilised so that the QCL remains within the locking range for long periods of time. (2) The QCL frequency and phase track the microwave frequency so that the QCL may be tuned with extremely high precision. (3) By changing the locking point for the PLL the phase of QCL relative to the reference frequency could be controlled within a range 0.4p, limited by the PLL, with a constant amplitude.", "author_names": [ "Reshma Anamari Mohandas", "Lalitha Ponnampalam", "Lianhe Li", "Cyril C Renaud", "Alwyn J Seeds", "Paul Dean", "Edmund H Linfield", "Giles Davies", "Joshua R Freeman" ], "corpus_id": 126597294, "doc_id": "126597294", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Phase control of a terahertz quantum cascade laser using an optical injection phase lock loop (Conference Presentation)", "venue": "Novel In Plane Semiconductor Lasers XVIII", "year": 2019 }, { "abstract": "The ability to engineer quantum cascade lasers (QCLs) with ultrabroad gain spectra, and with a full compensation of the group velocity dispersion, at terahertz (THz) frequencies, is key for devising monolithic and miniaturized optical frequency comb synthesizers (FCSs) in the far infrared. In THz QCLs four wave mixing, driven by intrinsic third order susceptibility of the intersubband gain medium, self locks the optical modes in phase, allowing stable comb operation, albeit over a restricted dynamic range ~20% of the laser operational range) Here, we engineer miniaturized THz FCSs, comprising a heterogeneous THz QCL, integrated with a tightly coupled, on chip, solution processed, graphene saturable absorber reflector that preserves phase coherence between lasing modes, even when four wave mixing no longer provides dispersion compensation. This enables a high power (8 mW) FCS with over 90 optical modes, through 55% of the laser operational range. We also achieve stable injection locking, paving the way to a number of key applications, including high precision tunable broadband spectroscopy and quantum metrology.", "author_names": [ "Francesco P Mezzapesa", "Katia Garrasi", "Johannes Schmidt", "Luca Salemi", "Valentino Pistore", "L Li", "A G Davies", "Edmund H Linfield", "Michael Riesch", "Christian Jirauschek", "Tian Carey", "Felice Torrisi", "Andrea C Ferrari", "Mathias Nest", "CNR-Istituto Nanoscienze", "Scuola Normale Superiore", "", "School of Electronic", "Electrical Engineering", "University of Leeds", "Department of Electrical", "Computer Engineering", "Technical University of Munich", "Cambridge Graphene Centre", "University of Cambridge" ], "corpus_id": 227127019, "doc_id": "227127019", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Terahertz Frequency Combs Exploiting an On Chip, Solution Processed, Graphene Quantum Cascade Laser Coupled Cavity", "venue": "ACS photonics", "year": 2020 }, { "abstract": "Due to intersubband transitions, the quantum cascade laser (QCL) is free of relaxations and able to work under fast modulations. In this work, the authors investigate the fast modulation properties of a continuous wave (cw) terahertz QCL emitting around 3 THz ~100 mm) Both simulation and experimental results show that the 3 dB modulation bandwidth for the device can reach 11.5 GHz and the modulation response curve is relatively flat upto ~16 GHz. The radio frequency (RF) injection measurements verify that around the laser threshold the inter mode beat note interacts strongly with the RF signal and the laser can be modulated at the round trip frequency of 15.5 GHz.", "author_names": [ "Li Gu", "Wenjian Wan", "Y H Zhu", "Zhanglong Fu", "Hua Li", "Juncheng Cao" ], "corpus_id": 114184383, "doc_id": "114184383", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "High frequency modulation and injection locking of terahertz quantum cascade lasers", "venue": "", "year": 2017 }, { "abstract": "Abstract We report a homogeneous quantum cascade laser (QCL) emitting at terahertz (THz) frequencies, with a total spectral emission of about 0.6 THz, centered around 3.3 THz, a current density dynamic range J dr 1.53, and a continuous wave output power of 7 mW. The analysis of the intermode beatnote unveils that the devised laser operates as an optical frequency comb (FC) synthesizer over the whole laser operational regime, with up to 36 optically active laser modes delivering ~200 uW of optical power per optical mode, a power level unreached so far in any THz QCL FC. A stable and narrow single beatnote, reaching a minimum linewidth of about 500 Hz, is observed over a current density range of 240 A/cm2 and even across the negative differential resistance region. We further prove that the QCL FC can be injection locked with moderate radio frequency power at the intermode beatnote frequency, covering a locking range of 1.2 MHz. The demonstration of stable FC operation, in a QCL, over the full current density dynamic range, and without any external dispersion compensation mechanism, makes our proposed homogenous THz QCL an ideal tool for metrological applications requiring mode hop electrical tunability and a tight control of the frequency and phase jitter.", "author_names": [ "Alessandra Di Gaspare", "Leonardo Viti", "Harvey E Beere", "David Ritchie", "Miriam Serena Vitiello" ], "corpus_id": 224891819, "doc_id": "224891819", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Homogeneous quantum cascade lasers operating as terahertz frequency combs over their entire operational regime", "venue": "", "year": 2020 }, { "abstract": "We demonstrate that the cavity resonance frequency the round trip frequency of terahertz quantum cascade lasers can be injection locked by direct modulation of the bias current using an RF source. Metal metal and single plasmon waveguide devices with roundtrip frequencies up to 35GHz have been studied, and show locking ranges above 200MHz. Inside this locking range the laser round trip frequency is phase locked, with a phase noise determined by the RF synthesizer. We find a square root dependence of the locking range with RF power in agreement with classical injection locking theory. These results are discussed in the context of mode locking operation.", "author_names": [ "Pierre Gellie", "Stefano Barbieri", "Jean-Francois Lampin", "Pascal G Filloux", "C Manquest", "Carlo Sirtori", "Isabelle Sagnes", "Suraj P Khanna", "Edmund H Linfield", "Harvey E Beere", "David A Ritchie" ], "corpus_id": 28065843, "doc_id": "28065843", "n_citations": 81, "n_key_citations": 2, "score": 0, "title": "Injection locking of terahertz quantum cascade lasers up to 35GHz via RF amplitude modulation", "venue": "35th International Conference on Infrared, Millimeter, and Terahertz Waves", "year": 2010 }, { "abstract": "We demonstrate that the cavity resonance frequency the round trip frequency of terahertz quantum cascade lasers can be injection locked by direct modulation of the bias current using an RF source. Metal metal and single plasmon waveguide devices with roundtrip frequencies up to 35GHz have been studied, and show locking ranges above 200MHz. Inside this locking range the laser round trip frequency is phase locked, with a phase noise determined by the RF synthesizer. We find a square root dependence of the locking range with RF power in agreement with classical injection locking theory. These results are discussed in the context of mode locking operation.", "author_names": [ "Pierre Gellie", "Stefano Barbieri", "Jean-Francois Lampin", "Pascal G Filloux", "C Manquest", "Carlo Sirtori", "Isabelle Sagnes", "Suraj P Khanna", "Edmund H Linfield", "Harvey E Beere", "David A Ritchie" ], "corpus_id": 123269103, "doc_id": "123269103", "n_citations": 9, "n_key_citations": 3, "score": 0, "title": "Injection locking of terahertz quantum cascade lasers up to 35GHz via RF amplitude modulation", "venue": "", "year": 2010 }, { "abstract": "It is demonstrated that the cavity resonance frequency the round trip frequency of terahertz quantum cascade lasers can be injection locked by direct modulation of the bias current using an RF source. Metal metal and single plasmon waveguide devices with round trip frequencies up to 35 GHz have been studied, and show locking ranges above 200 MHz. A square root dependence of the locking range with RF power was found to be in agreement with classical injection locking theory. Inside this locking range the laser round trip frequency is phase locked, with a phase noise determined by the RF synthesiser, leading to the generation of modelocked pulses with low timing jitter.", "author_names": [ "Pierre Gellie", "Jean-Francois Lampin", "Carlo Sirtori", "Stefano Barbieri" ], "corpus_id": 111018585, "doc_id": "111018585", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "RF injection locking of terahertz quantum cascade lasers", "venue": "", "year": 2010 }, { "abstract": "We report on the Doppler free saturation spectroscopy of a molecular transition at 3.3 THz based on a quantum cascade laser and an absorption cell in a collinear pump probe configuration. A Lamb dip with a sub Doppler linewidth of 170 kHz is observed for a rotational transition of HDO. We found that a certain level of external optical feedback is tolerable as long as the free spectral range of the external cavity is large compared to the width of the absorption line. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement OCIS codes: (140.5965) Semiconductor lasers, quantum cascade; (280.4788) Optical sensing and sensors; (300.6320) Spectroscopy, high resolution; (300.6495) Spectroscopy, terahertz. References and links 1. M. S. Vitiello, L. Consolino, S. Bartalini, A. Taschin, A. Tredicucci, M. Inguscio, and P. De Natale, \"Quantum limited frequency fluctuations in a terahertz laser,\" Nat. Photonics 6, 525 528 (2012) 2. J. L. Kloosterman, D. J. Hayton, Y. Ren, T. Y. Kao, J. N. Hovenier, J. R. Gao, T. M. Klapwijk, Q. Hu, C. K. Walker, and J. L. Reno, \"Hot electron bolometer heterodyne receiver with a 4.7 THz quantum cascade laser as a local oscillator,\" Appl. Phys. Lett. 102, 011123 (2013) 3. H. Richter, M. Wienold, L. Schrottke, K. Biermann, H. T. Grahn, and H. W. Hubers, \"4.7 THz local oscillator for the GREAT heterodyne spectrometer on SOFIA,\" IEEE Trans. Terahertz Sci. Technol. 5, 539 545 (2015) 4. D. Buchel, P. Putz, K. Jacobs, M. Schultz, U. U. Graf, C. Risacher, H. Richter, O. Ricken, H. W. Hubers, R. Gusten, C. E. Honingh, and J. Stutzki, \"4.7 THz superconducting hot electron bolometer waveguide mixer,\" IEEE Trans. Terahertz Sci. Technol. 5, 207 214 (2015) 5. C. Risacher, R. Gusten, J. Stutzki, H. W. Hubers, D. Buchel, U. U. Graf, S. Heyminck, C. E. Honingh, K. Jacobs, B. Klein, T. Klein, C. Leinz, P. Putz, N. Reyes, O. Ricken, H. J. Wunsch, P. Fusco, and S. Rosner, \"First supra THz heterodyne array receivers for astronomy with the SOFIA observatory,\" IEEE Trans. Terahertz Sci. Technol. 6, 199 211 (2016) 6. L. Rezac, P. Hartogh, R. Gusten, H. Wiesemeyer, H. W. Hubers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, \"First detection of the 63 mm atomic oxygen line in the thermosphere ofMars with GREAT/SOFIA,\" Astron. Astrophys. 580, L10 (2015) 7. J. Remillard, D. Uy, W. Weber, F. Capasso, C. Gmachl, A. Hutchinson, D. Sivco, J. Baillargeon, and A. Cho, \"Sub Doppler resolution limited Lamb dip spectroscopy of NO with a quantum cascade distributed feedback laser,\" Opt. Express 7, 243 248 (2000) 8. N. Mukherjee, R. Go, and C. K. N. Patel, \"Linewidth measurement of external grating cavity quantum cascade laser using saturation spectroscopy,\" Appl. Phys. Lett. 92, 111116 (2008) 9. S. Bartalini, S. Borri, and P. De Natale, \"Doppler free polarization spectroscopy with a quantum cascade laser at 4.3 mm,\" Opt. Express 17, 7440 7449 (2009) 10. R. J. Walker, J. Kirkbride, J. H. van Helden, D. Weidmann, and G. A. D. Ritchie, \"Sub Doppler spectroscopy with an external cavity quantum cascade laser,\" Appl. Phys. B 112, 159 167 (2013) 11. J. C. Pearson, B. J. Drouin, A. Maestrini, I. Mehdi, J. Ward, R. H. Lin, S. Yu, J. J. Gill, B. Thomas, C. Lee, G. Chattopadhyay, E. Schlecht, F. W. Maiwald, P. F. Goldsmith, and P. Siegel, \"Demonstration of a room temperature 2.48 2.75 THz coherent spectroscopy source,\" Rev. Sci. Instrum. 82, 093105 (2011) 12. G. Cazzoli and C. Puzzarini, \"Sub Doppler resolution in the THz frequency domain: 1 kHz accuracy at 1 THz by exploiting the Lamb dip technique,\" J. Phys. Chem. A 117, 13759 13766 (2013) Vol. 26, No. 6 19 Mar 2018 OPTICS EXPRESS 6692 #315862 https:/doi.org/10.1364/OE.26.006692 Journal (c) 2018 Received 18 Dec 2017; revised 14 Feb 2018; accepted 14 Feb 2018; published 5 Mar 2018 13. L. Consolino, A. Campa, M. Ravaro, D. Mazzotti, M. S. Vitiello, S. Bartalini, and P. De Natale, \"Saturated absorption in a rotational molecular transition at 2.5 THz using a quantum cascade laser,\" Appl. Phys. Lett. 106, 021108 (2015) 14. M. Wienold, L. Schrottke, M. Giehler, R. Hey, W. Anders, and H. T. Grahn, \"Low voltage terahertz quantum cascade lasers based on LO phonon assisted interminiband transitions,\" Electron. Lett. 45, 1030 1031 (2009) 15. H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Muller, \"Submillimeter, millimeter, and microwave spectral line catalog,\" J. Quant. Spectrosc. Radiat. Transfer 60, 883 890 (1998) 16. W. Demtroder, Laser spectroscopy, vol. 2 (Springer, 2008) 17. V. S. Letokhov and V. P. Chebotayev, Nonlinear laser spectroscopy (Springer, 1977) 18. H. Richter, S. G. Pavlov, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, D. A. Ritchie, and H. W. Hubers, \"Submegahertz frequency stabilization of a terahertz quantum cascade laser to a molecular absorption line,\" Appl. Phys. Lett. 96, 071112 (2010) 19. N. van Marrewijk, B. Mirzaei, D. Hayton, J. R. Gao, T. Y. Kao, Q. Hu, and J. L. Reno, \"Frequency locking and monitoring based on bi directional terahertz radiation of a 3rd order distributed feedback quantum cascade laser,\" J. Infrared Millim. Terahertz Waves 36, 1210 1220 (2015) 20. H. W. Hubers, H. Richter, R. Eichholz, M. Wienold, K. Biermann, L. Schrottke, and H. T. Grahn, \"Heterodyne spectroscopy of frequency instabilities in terahertz quantum cascade lasers induced by optical feedback,\" IEEE J. Sel. Top. Quantum Electron. 23, 1800306 (2017) 21. R. Lang and K. Kobayashi, \"External optical feedback effects on semiconductor injection laser properties,\" IEEE J. Quantum Electron. QE 16, 347 355 (1980) 22. A. D. Rakic, T. Taimre, K. Bertling, Y. L. Lim, P. Dean, D. Indjin, Z. Ikonic, P. Harrison, A. Valavanis, S. P. Khanna, M. Lachab, S. J. Wilson, E. H. Linfield, and A. G. Davies, \"Swept frequency feedback interferometry using terahertz frequency QCLs: a method for imaging and materials analysis,\" Opt. Express 21, 22194 22205 (2013) 23. M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H. W. Hubers, \"Real time terahertz imaging through self mixing in a quantum cascade laser,\" Appl. Phys. Lett. 109, 011102 (2016)", "author_names": [ "W M", "", "A T", "S L", "Guo H-T" ], "corpus_id": 198949456, "doc_id": "198949456", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Doppler free spectroscopy with a terahertz quantum cascade laser", "venue": "", "year": 2018 } ]

[ { "abstract": "A structurally stable crystalline carbon allotrope is predicted by means of the first principles calculations. This allotrope can be derived by substituting each atom in diamond with a carbon tetrahedron, and possesses the same space group Fd3m as diamond, which is thus coined as T carbon. The calculations on geometrical, vibrational, and electronic properties reveal that T carbon, with a considerable structural stability and a much lower density 1.50 g/cm3, is a semiconductor with a direct band gap about 3.0 eV, and has a Vickers hardness 61.1 GPa lower than diamond but comparable with cubic boron nitride. Such a form of carbon, once obtained, would have wide applications in photocatalysis, adsorption, hydrogen storage, and aerospace materials.", "author_names": [ "Xian-Lei Sheng", "Qing-Bo Yan", "Fei Ye", "Qing-Rong Zheng", "Gang Su" ], "corpus_id": 22068905, "doc_id": "22068905", "n_citations": 291, "n_key_citations": 3, "score": 1, "title": "T carbon: a novel carbon allotrope.", "venue": "Physical review letters", "year": 2011 }, { "abstract": "Abstract A novel carbon allotrope, denoted P2/m C54, is proposed in this work. The structural properties, mechanical properties, mechanical and dynamical stability, relative formation enthalpy, anisotropy in Young's modulus and electronic properties for P2/m C54 are investigated in this work. First, P2/m C54 is found to remain mechanically and dynamically stable below 100 GPa, with a relative formation enthalpy that is 0.729 eV/atom less than that of T carbon. The bulk modulus, shear modulus and Young's modulus of P2/m C54 are calculated to be 345 GPa, 332 GPa and 754 GPa, respectively; the hardness of P2/m C54 is calculated to be 54.1 GPa and 70.4 GPa using Chen's model and Lyakhov and Oganov's model, respectively. All these calculations suggest that P2/m C54 is a potential superhard material. Furthermore, the band gap of P2/m C54 is determined to be 4.95 eV; in other words, P2/m C54 is an indirect band gap semiconductor material with a wide band gap at ambient pressure.", "author_names": [ "Xiaozhen Li", "Mengjiang Xing" ], "corpus_id": 214208096, "doc_id": "214208096", "n_citations": 27, "n_key_citations": 0, "score": 0, "title": "Prediction of a novel carbon allotrope from first principle calculations: A potential superhard material in monoclinic symmetry", "venue": "", "year": 2020 }, { "abstract": "Through first principles calculations, we predict a new superhard carbon allotrope named C 20 T, which possesses a cubic T symmetry with space group No.198(P213) This new carbon allotrope has an all sp (3) hybridized bonding network with 20 atoms in its primitive unit cell. The dynamic, mechanical, and thermal stabilities of this new carbon phase at zero pressure are confirmed by using a variety of state of the art theoretical calculations. Interestingly, despite the fact that C 20 T carbon has a porous structure with large cavities, our calculations identify its superhard properties with the Vickers hardness of 72.76 Gpa. The ideal tensile and shear strength of C 20 T carbon are calculated to be 71.1 and 55.2 GPa respectively, comparable to that of c BN. Electronic band calculations reveal that this new carbon allotrope is a transparent insulator with an indirect band gap of 5.44 eV. These results broaden our understanding of superhard carbon allotropes.", "author_names": [ "Jia-Qi Wang", "Chunxiang Zhao", "Chunyao Niu", "Qiang Sun", "Yu Jia" ], "corpus_id": 6478784, "doc_id": "6478784", "n_citations": 32, "n_key_citations": 0, "score": 0, "title": "C 20 T carbon: a novel superhard sp (3) carbon allotrope with large cavities.", "venue": "Journal of physics. Condensed matter an Institute of Physics journal", "year": 2016 }, { "abstract": "By means of ab initio computations and the global minimum structure search method, we have investigated structural, mechanical, and electronic properties of D carbon, a crystalline orthorhombic sp3 carbon allotrope (space group Pmma D2h5 with 6 atoms per cell) Total energy calculations demonstrate that D carbon is energetically more favorable than the previously proposed T6 structure (with 6 atoms per cell) as well as many others. This novel phase is dynamically, mechanically, and thermally stable at zero pressure and more stable than graphite beyond 63.7 GPa. D carbon is a semiconductor with a bandgap of 4.33 eV, less than diamond's gap (5.47 eV) The simulated X ray diffraction pattern is in satisfactory agreement with previous experimental data in chimney or detonation soot, suggesting its possible presence in the specimen.", "author_names": [ "Dong Fan", "Shaohua Lu", "Andrey A Golov", "Artem A Kabanov", "Xiaojun Hu" ], "corpus_id": 52812590, "doc_id": "52812590", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "D carbon: Ab initio study of a novel carbon allotrope.", "venue": "The Journal of chemical physics", "year": 2018 }, { "abstract": "A novel cubic porous carbon allotrope C96 carbon with intriguing physical properties was predicted. It has 96 atoms in the conventional cell, possessing a Pmm space group. The basic building block of C96 carbon is a planar six membered carbon ring. The structural stability, mechanical properties, and dynamical properties of C96 carbon were extensively studied. It is a semiconductor (1.85 eV) with a lower density (2.7 g cm 3) and a larger bulk modulus (279 GPa) and is stable under ambient conditions. The hardness of C96 carbon (25 GPa) is larger than that of T carbon (5.6 GPa) Due to the structural porous feature and lower density, C96 carbon can also be expected to be a good hydrogen storage material.", "author_names": [ "Da Li", "Fubo Tian", "Binhua Chu", "Defang Duan", "Shuli Wei", "Yunzhou Lv", "Huadi Zhang", "Lu Cai Wang", "Nan Lu", "Bingbing Liu", "Tian Cui" ], "corpus_id": 98021719, "doc_id": "98021719", "n_citations": 32, "n_key_citations": 1, "score": 0, "title": "Cubic C96: a novel carbon allotrope with a porous nanocube network", "venue": "", "year": 2015 }, { "abstract": "Abstract Based on density functional theory, a novel carbon allotrope in the Pm 3m space group with cubic symmetry (denoted as cP144 carbon below) is proposed in this work; the conventional cell of the allotrope contains 144 carbon atoms, and its structural properties, mechanical anisotropy properties, electronic properties, and mechanical properties are also predicted. The cP144 carbon is dynamically and mechanically stable, and the related enthalpy of cP144 carbon is smaller than that of T carbon, Y carbon, TY carbon, TII carbon, YII carbon and TYII carbon. cP144 carbon is a carbon material with a microporous structure, and the maximum distance of the microporous structure is 12.172 A together with a minimum distance of 9.918 A. cP144 carbon may be used for hydrogen and lithium storage materials. The electronic band structure calculations showed that cP144 carbon is a direct band gap semiconductor material with a band gap of 0.34 eV; such a material can also be considered a photoelectric material. The density of cP144 (1.149 g/cm3) is only approximately two thirds that of T carbon. The bulk modulus of cP144 carbon is 101 GPa higher than that of Y carbon and TY carbon.", "author_names": [ "Qingyang Fan", "Yingxiu Zhao", "Xinhai Yu", "YanXing Song", "Wei Zhang", "Sining Yun" ], "corpus_id": 216194685, "doc_id": "216194685", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Physical properties of a novel microporous carbon material", "venue": "", "year": 2020 }, { "abstract": "A novel allotrope of carbon with P2/m symmetry was identified during an ab initio minima hopping structural search which we call M10 carbon. This structure is predicted to be more stable than graphite at pressures above 14.4 GPa and consists purely of sp3 bonds. It has a high bulk modulus and is almost as hard as diamond. A comparison of the simulated X ray diffraction pattern shows a good agreement with experimental results from cold compressed graphite.", "author_names": [ "Maximilian Amsler", "Jose A Flores-Livas", "Miguel A L Marques", "Silvana Botti", "Stefan Goedecker" ], "corpus_id": 118529757, "doc_id": "118529757", "n_citations": 14, "n_key_citations": 1, "score": 0, "title": "Prediction of a novel monoclinic carbon allotrope", "venue": "", "year": 2012 }, { "abstract": "Owing to the various ways of chemical bonding, carbon can form abundant allotropes with different frameworks, which harbor rich mechanical and electronic properties. Taking the cage like isomer of C16cluster as building block, we design a new low density carbon allotrope, which has the tetragonal symmetry (I4/mmm) and a 56 atoms unit cell, hence termed as T C56. Our first principles calculations reveal that T C56is not only energetically, dynamically, thermally (above 1800 K) and mechanically stable, but even more stable than the experimentally synthesized C20 sc and T carbon. Remarkably, although the framework of T C56is low density (2.72g/cm3) it exhibits novel superhard properties with a Vickers hardness of 48.71 GPa. The obtained Yang's modulus and ideal strength shows that T C56is mechanically anisotropic. In particular, our analysis of electronic and optical properties suggest that T C56is a transparent indirect semiconductor with a wide bandgap of 3.18 eV (HSE06) These findings highlight a distinct carbon allotrope, having promising applications for optical and aerospace devices due to its light, transparent, superhard features.", "author_names": [ "Yanqing Guo", "Leyuan Cui", "Ding Zhao", "T L Song", "Xin Cui", "Zhifeng Liu" ], "corpus_id": 209676826, "doc_id": "209676826", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "T C56: A low density transparent superhard carbon allotrope assembled from C16 cage like cluster.", "venue": "Journal of physics. Condensed matter an Institute of Physics journal", "year": 2020 }, { "abstract": "A novel allotrope of carbon with P2/m symmetry was identified during an ab initio minimahopping structural search which we call M10 carbon. This structure is predicted to be more stable than graphite at pressures above 14.4 GPa and consists purely of sp bonds. It has a high bulk modulus and is almost as hard as diamond. A comparison of the simulated X ray diffraction pattern shows a good agreement with experimental results from cold compressed graphite. Graphite and diamond are the thermodynamically most stable forms of carbon at ambient conditions. However, carbon can be found in a vast structural variety due to its flexibility to form sp spand sphybridized bonds: hexagonal diamond, nano diamond, carbon foams, fullerenes and nanotubes are just some examples of known carbon allotropes. Experimental evidences of a novel super hard carbon phase have been reported in literature when graphite is compressed at room temperatures. Changes in resistivity [1] optical transmittance [2,3] optical reflectivity [4] X ray diffraction (XRD) patterns [5 7] and in the raman spectra [8,9] indicate a phase transition in the range of 10 to 25GPa. Recently, several candidate structures have been proposed to match these experimental observations [10] such as M carbon [11] bct C4 carbon [12] W carbon [13] and Z carbon [8,14] Although Z carbon is thermodynamically the most promising structure, a final and conclusive determination has not yet been possible. In this article we report on a novel carbon allotrope discovered with the recently developed minima hopping crystal structure prediction method (MHM) [15,16] The MHM is capable to predict the most stable and metastable structures given solely the chemical composition of a system. Short molecular dynamics simulations are used to escape from local minima, and local geometry relaxations are performed to identify stable configurations. High efficiency of the escape step is ensured by aligning the initial molecular dynamics velocities along soft mode directions, and revisiting already explored regions of the potential energy surface is avoided by a feedback mechanism. The minima hopping method has been successfully used in a wide range of applications [8,17 21] a e mail: silvana.botti@univ lyon1.fr b e mail: [email protected] During our MHM simulations, the energies and the Hellman Feynman forces were evaluated at the density functional theory (DFT) level within the local density approximation (LDA) and the all electron projectoraugmented wave method was employed as implemented in the abinit code [22,23] The most promising structures were further relaxed using norm conserving HartwigsenGoedecker Hutter (HGH) pseudopotentials [24] The total energy was converged within less than 1 meV per atom by a plane wave cut off energy of 2100 eV and well converged Monkhorst Pack k point meshes. We reconfirmed the energy ordering with two other exchangecorrelation functionals within the generalized gradient approximation, namely PBE [25] and PBEsol [26] Several MHM simulations were carried out with cells containing up to 8 atoms at 15 GPa within an unconstrained and thorough structural search, starting from different input configurations. We identified a novel, monoclinic carbon phase with P2/m symmetry, which we call M10 carbon. It consists solely of sp bonds and contains 8 atoms per cell. At ambient pressure, the unit cell parameters are given by a 4.080 A, b 2.498 A, c 4.728 A, a g 90* and b 73.96* Two carbon atoms each occupy the crystallographic 2n sites at 0.1, 0.5, 0.113) and 0.132, 0.5, 0.421) and the 2m sites at 0.333, 0, 0.466) and 0.325, 0, 0.117) The overall structure is closely related to M carbon, also consisting of 5and 7 membered rings along the b axis, while 6 membered rings are formed along the c axis. In contrast to M carbon, the 5 rings share the long edge, whereas in M10 carbon they share the short edge. The structure is illustrated in Figure 1. The dynamical stability was investigated by analyzing the phonon dispersion within the whole Brillouin zone. Density functional perturbation theory [27] as Page 2 of 3 Eur. Phys. J. B (2013) 86: 383 Fig. 1. The structure of M10 carbon from two different angles. The left panel shows the 5and 7 membered rings, while the right panel reveals the 6 membered rings. 200 100 0 100 200 300 0 5 10 15 20 25 D m eV Pressure (GPa) Graphite bct C4 M carbon W carbon Hex diamond Cub diamond Z carbon M10 carbon Fig. 2. Enthalpy differences per atom with respect to graphite of several carbon allotropes are shown as a function of pressure. The most promising candidate is Z carbon since it crosses the graphite line at roughly 10 GPa. However, M10 carbon becomes thermodynamically accessible above 14.4 GPa. implemented in abinit, was employed with a 12x12x12 k point sampling and a 4 x 4 x 4 q point mesh. No imaginary phonon frequencies were found, confirming the lattice stability of the phase. The thermodynamical stability of M10 carbon was investigated by computing its enthalpy within a wide pressure range. In Figure 2, the enthalpies of all proposed candidates for cold compressed graphite are plotted with respect to graphite as a function of pressure, neglecting the zero point vibrational energies. M10 carbon becomes enthalpically favorable over graphite above a pressure of 14.4 GPa. As expected from the structural similarities with M carbon, both M10and M carbon are very close in enthalpy throughout the whole pressure range with an enthalpy difference of merely 3.9 meV/atom at 15 GPa. The vibrational contribution to the free energy within the harmonic approximation at 300 K reduces this value insignificantly by 0.003 meV/atom. In Table 1, we compare the structural properties of M10 carbon with other carbon allotropes. The bulk moduli B0 were computed using the Murnaghan equation, and the Vickers hardnesses Hv were estimated with the method of Gao et al. [28] Like all of the investigated Table 1. Calculated and experimental data (where available) of the bulk moduli B0 (in GPa) Vickers Hardness Hv (in GPa) and volumes per atom V0 (in A /atom) at 0 GPa for bct C4, M W Z M10 carbon and diamond. Structure Method B0 (GPa) Hv (GPa) V0 (A) bct C4 this work 428.2 93.5 5.82 LDA [13] 433.7 5.83 M carbon this work 428.4 93.9 5.77 LDA [11] 431.2 83.1 5.78 W carbon this work 427.5 94.2 5.75 LDA [13] 444.5 5.76 Cub diamond this work 463.0 97.8 5.51 LDA [13] 466.3 5.52 Expt. 446 60 120b 5.67 Z carbon LDA [8] 441.5 95.4 5.66 M10 carbon this work 423.7 93.5 5.79 a Reference [29] b reference [30] Fig. 3. The simulated XRD patterns are compared with the experimental results from reference [7] of cold compressed graphite. While at 13.7 GPa graphite was used to compute the simulated XRD pattern, M10 carbon was used for the simulation at 23.9 GPa. structures, M10 carbon is nearly as hard as diamond and has a very high bulk modulus, which could well account for ring cracks in diamond anvil cells [7] Furthermore, an analysis of the electronic band tructure was carried out, showing that M10 carbon is a wide band gap semiconductor with an indirect PBE gap of 4.4 eV at 0 GPa. Finally, we compare the XRD pattern of M10 carbon to experimental measurements from reference [7] as illustrated in Figure 3. The simulated pattern gives a good match to the experimental spectrum and could well explain the observed changes. It can, therefore, be expected that M10 carbon is present in samples of coldcompressed graphite above 14.4 GPa. However, other carbon allotropes show a similarly good agreement and thus the XRD pattern alone is by no way a conclusive evidence. In conclusion, we present a novel carbon allotrope that we call M10 carbon. It is a transparent, super hard material which becomes enthalpically favorable over Eur. Phys. J. B (2013) 86: 383 Page 3 of 3 graphite at pressures above 14.4 GPa. Both the structural and enthalpical properties are very similar to the previously proposed M carbon [11] The XRD pattern is in good agreement with experimental measurements, and although other carbon allotropes are enthalpically preferred at lower pressures, it could well be synthesized in samples of cold compressed graphite. Financial support provided by the Swiss National Science Foundation is gratefully acknowledged. Computational resources were provided by the Swiss National Supercomputing Center (CSCS) in Lugano and IDRIS GENCI (project x2012096017) in France.", "author_names": [ "Maximilian Amsler", "Jose A Flores-Livas", "Miguel A L Marques", "Silvana Botti", "Stefan Goedecker" ], "corpus_id": 55094254, "doc_id": "55094254", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "THE EUROPEAN PHYSICAL JOURNAL B Prediction of a novel monoclinic carbon allotrope", "venue": "", "year": 2013 }, { "abstract": "A novel stable carbon allotrope is predicted by using first principles calculations. This allotrope is obtained by replacing one of the two atoms in the primitive cell of diamond with a carbon tetrahedron, thus it contains five atoms in one primitive cell, termed T5 carbon. The stabilities of T5 carbon are checked in structural, thermal, vibrational and energy calculations. The calculations on electronic, thermal, and mechanical properties reveal that T5 carbon is a semiconductor with an indirect band gap of 3.18 eV, and has a lattice thermal conductivity of 409 W/mK. More importantly, the Vickers hardness of T5 carbon is 76.5 GPa which is lower than that of diamond but larger than those of T carbon and cubic boron nitride, confirming the superhard properties of T5 carbon, suggesting its wide applications in mechanical devices.", "author_names": [ "Xian-Yong Ding", "Chao Zhang", "Dong-qi Wang", "Bingsheng Li", "Qingping Wang", "Zhi Gen Yu", "Kah-Wee Ang", "Yong-Wei Zhang" ], "corpus_id": 218538035, "doc_id": "218538035", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A potential superhard carbon allotrope: T5 carbon", "venue": "", "year": 2020 } ]

[ { "abstract": "Photonic integrated circuits (PICs) are attractive platforms to perform large scale quantum information processing. While highly functional PICs (e.g. silicon based photonic circuits) and high performance single photon sources (SPSs, e.g. compound semiconductor quantum dots (QDs) have been independently demonstrated, their combination for single photon based applications has still been limited. This is largely due to the complexities of introducing SPSs into existing PIC platforms, which are generally realized with different materials and using distinct fabrication protocols. Here, we report a novel approach to combine SPSs and PICs prepared independently. We employ transfer printing, by which multiple desired SPSs can be integrated in a simple pick and place manner with a theoretical waveguide coupling efficiency >99% fulfilling the demanding requirements of large scale quantum applications. Experimentally, we demonstrated QD based SPSs with high waveguide coupling efficiencies, together with the integration of two SPSs into a waveguide. Our approach will accelerate scalable fusion between modern PICs and cutting edge quantum technologies.", "author_names": [ "Ryota Katsumi", "Yasutomo Ota", "Masahiro Kakuda", "Satoshi Iwamoto", "Yasuhiko Arakawa" ], "corpus_id": 67289254, "doc_id": "67289254", "n_citations": 40, "n_key_citations": 1, "score": 1, "title": "Transfer printed single photon sources coupled to wire waveguides", "venue": "", "year": 2018 }, { "abstract": "We report quantum dot single photon sources coupled to glass clad wire waveguides by transfer printing, which enables the heterogeneous source integration in a simple pick and place manner. A high waveguide coupling efficiency >60% is experimentally demonstrated.", "author_names": [ "Ryota Katsumi", "Yasutomo Ota", "Masahiro Kakuda", "Satoshi Iwamoto", "Yasuhiko Arakawa" ], "corpus_id": 51982047, "doc_id": "51982047", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Quantum dot single photon sources transfer printed on wire waveguides", "venue": "2018 Conference on Lasers and Electro Optics (CLEO)", "year": 2018 }, { "abstract": "Single photon sources are key components for various quantum information processings. For practical quantum applications, bright single photon sources with efficient fiber optical interfaces are highly required. Here, bright fiber coupled single photon sources based on InAs quantum dots are demonstrated through the k vector matching between a microfiber mode and a normal mode of the linear photonic crystal cavity. One of the modes of the linear photonic crystal cavity whose k vector is similar to that of the microfiber mode is employed. From independent transmission measurement, the coupling efficiency directly into the fiber of 58% is obtained. When the quantum dot and cavity system is non resonantly pumped with 80 MHz pulse train, a raw count rate of 1.81 MHz is obtained with g(0) 0.46. Resonant pump is expected to improve the rather high g(0) value. Time resolved photoluminescence is also measured to confirm the three fold Purcell enhancement. This system provides a promising route for efficient direct fiber collections of single photons for quantum information processing. (c) 2016 Optical Society of America OCIS codes: (230.5590) Quantum well, wire and dot devices; (230.5298) Photonic crystals; (270.0270) Quantum Optics; References and links 1. N. Gisin, G. G. Ribordy, W. Tittel, and H. Zbinden, \"Quantum cryptography,\" Rev. Mod. Phys. 74, 145 195 (2002) 2. E. Knill, R. Laflamme, and G. J. Milburn, \"A scheme for efficient quantum computation with linear optics,\" Nature 409, 46 52 (2001) 3. S. Buckley, K. Rivoire, and J. Vuckovic, \"Engineered quantum dot single photon sources,\" Rep. Prog. Phys. 75, 126503 (2012) 4. M. Pelton, C. Santori, J. Vuckovic, B. Zhang, G. Solomon, J. Plant, and Y. Yamamoto, \"Efficient Source of Single Photons: A Single Quantum Dot in a Micropost Microcavity,\" Phys. Rev. Lett. 89, 233602 (2002) 5. C. Santori, D. Fattal, J. Vuckovic, G. S. Solomon, and Y. Yamamoto, \"Single photon generation with InAs quantum dots,\" New J. Phys. 6, 89 89 (2004) 6. W. H. Chang, W. Y. Chen, H. S. Chang, T. P. Hsieh, J. I. Chyi, and T. M. Hsu, \"Efficient Single Photon Sources Based on Low Density Quantum Dots in Photonic Crystal Nanocavities,\" Phys. Rev. Lett. 96, 117401 (2006) 7. S. Strauf, N. G. Stoltz, M. T. Rakher, L. A. Coldren, P. M. Petroff, and D. Bouwmeester, \"High frequency single photon source with polarization control,\" Nature Photonics 1, 704 708 (2007) 8. J. Claudon, J. Bleuse, N. S. Malik, M. Bazin, P. Jaffrennou, N. Gregersen, C. Sauvan, P. Lalanne, and J. M. Gerard, \"A highly efficient single photon source based on a quantum dot in a photonic nanowire,\" Nature Photonics 4, 174 177 (2010) 9. A. Laucht, S. Putz, T. Gunthner, N. Hauke, R. Saive, S. Frederick, M. Bichler, M. C. Amann, A. Holleitner, M. Kaniber, and J. Finley, \"A Waveguide Coupled On Chip Single Photon Source,\" Phys. Rev. X 2, 011014 (2012) 10. O. Gazzano, S. M. de Vasconcellos, and C. Arnold, \"Bright solid state sources of indistinguishable single photons,\" Nature Communications (2013) 11. K. H. Madsen, S. Ates, J. Liu, A. Javadi, S. M. Albrecht, I. Yeo, S. Stobbe, and P. Lodahl, \"Efficient outcoupling of high purity single photons from a coherent quantum dot in a photonic crystal cavity,\" Phys. Rev. B 90, 155303 (2014) 12. L. Sapienza, M. Davanco, A. Badolato, and K. Srinivasan, \"Nanoscale optical positioning of single quantum dots for bright and pure single photon emission,\" Nature Communications 6, 7833 (2015) 13. P. Lodahl, S. Mahmoodian, and S. Stobbe, \"Interfacing single photons and single quantum dots with photonic nanostructures,\" Rev. Mod. Phys. 87, 347 400 (2015) 14. S. Unsleber, C. Schneider, S. Maier, Y. M. He, S. Gerhardt, C. Y. Lu, J. W. Pan, M. Kamp, and S. Hofling, \"Deterministic generation of bright single resonance fluorescence photons from a Purcellenhanced quantum dot micropillar system,\" Optics Express 23, 32977 (2015) 15. M. Gschrey, A. Thoma, P. Schnauber, M. Seifried, R. Schmidt, B. Wohlfeil, L. K. U. ger, J. H. Schulze, T. Heindel, S. Burger, F. Schmidt, A. Strittmatter, S. Rodt, and S. Reitzenstein, \"Highly indistinguishable photons from deterministic quantum dot microlenses utilizing threedimensional in situ electron beam lithography,\" Nature Communications 6, 1 8 (2015) 16. X. Ding, Y. He, Z. C. Duan, N. Gregersen, M. C. Chen, S. Unsleber, S. Maier, C. Schneider, M. Kamp, S. Hofling, C. Y. Lu, and J. W. Pan, \"On Demand Single Photons with High Extraction Efficiency and NearUnity Indistinguishability from a Resonantly Driven Quantum Dot in a Micropillar,\" Phys. Rev. Lett. 116, 020401 (2016) 17. N. Somaschi, V. Giesz, L. De Santis, L. J. C, A. M. P, G. Hornecker, P. S. L, T. Grange, C. Anton, J. Demory, C. Gomez, I. Sagnes, L. K. N. D, A. Lemaitre, A. Auffeves, W. A. G, L. Lanco, and P. Senellart, \"Near optimal single photon sources in the solid state,\" Nature Photonics 10, 340 345 (2016) 18. J. L. O'Brien, A. Furusawa, and J. Vuckovic, \"Photonic quantum technologies,\" Nature Photonics 3, 687 695 (2009) 19. M. Davanco, M. T. Rakher, W. Wegscheider, D. Schuh, A. Badolato, and K. Srinivasan, \"Efficient quantum dot single photon extraction into an optical fiber using a nanophotonic directional coupler,\" Appl. Phys. Lett. 99, 121101 (2011) 20. M. Fujiwara, K. Toubaru, T. Noda, H. Q. Zhao, and S. Takeuchi, \"Highly Efficient Coupling of Photons from Nanoemitters into Single Mode Optical Fibers,\" Nano Lett. 11, 4362 4365 (2011) 21. L. Liebermeister, F. Petersen, A. von Munchow, D. Burchardt, J. Hermelbracht, T. Tashima, A. W. Schell, O. Benson, T. Meinhardt, A. Krueger, A. Stiebeiner, A. Rauschenbeutel, H. Weinfurter, and M. Weber, \"Tapered fiber coupling of single photons emitted by a deterministically positioned single nitrogen vacancy center,\" Appl. Phys. Lett. 104, 031101 (2014) 22. S. Ates, I. Agha, A. Gulinatti, I. Rech, A. Badolato, and K. Srinivasan, \"Improving the performance of bright quantum dot single photon sources using temporal filtering via amplitude modulation,\" Sci. Rep. 3, 1397 (2013) 23. B. H. Ahn, C. M. Lee, H. J. Lim, T. W. Schlereth, M. Kamp, S. Hofling, and Y. H. Lee, \"Direct fibercoupled single photon source based on a photonic crystal waveguide,\" Appl. Phys. Lett. 107, 081113 (2015) 24. C. M. Lee, H. J. Lim, C. Schneider, S. Maier, S. Hofling, M. Kamp, and Y. H. Lee, \"Efficient single photon source based on m fibre coupled tunable microcavity,\" Sci. Rep. 5, 14309 (2015) 25. J. Johansen, S. Stobbe, I. Nikolaev, T. Lund Hansen, P. Kristensen, J. Hvam, W. Vos, and P. Lodahl, \"Size dependence of the wavefunction of self assembled InAs quantum dots from time resolved optical measurements,\" Phys. Rev. B 77, 073303 (2008) 26. M. Davanco, C. S. Hellberg, S. Ates, A. Badolato, and K. Srinivasan, \"Multiple time scale blinking in InAs quantum dot single photon sources,\" Phys. Rev. B 89, 161303 (2014) 27. M. Arcari, I. Sollner, A. Javadi, S. Lindskov Hansen, S. Mahmoodian, J. Liu, H. Thyrrestrup, E. H. Lee, J. D. Song, S. Stobbe, and P. Lodahl, \"Near Unity Coupling Efficiency of a Quantum Emitter to a Photonic Crystal Waveguide,\" Phys. Rev. Lett. 113, 093603 (2014) 28. D. Englund, D. Fattal, E. Waks, G. Solomon, B. Zhang, T. Nakaoka, Y. Arakawa, Y. Yamamoto, and J. Vuckovic, \"Controlling the Spontaneous Emission Rate of Single Quantum Dots in a Two Dimensional Photonic Crystal,\" Phys. Rev. Lett. 95, 013904 (2005) 29. S. H. Kim, G. H. Kim, S. K. Kim, H. G. Park, Y. H. Lee, and S. B. Kim, \"Characteristics of a stick waveguide resonator in a two dimensional photonic crystal slab,\" J. Appl. Phys. 95, 411 (2004) 30. R. Nagai and T. Aoki, \"Ultra low loss tapered optical fibers with minimal lengths,\" Opt. Express 22, 28427 28436 (2014) 31. H. A. Haus, \"Waves and Fields in Optoelectronics,\" Prentice Hall (1984) 32. J. D. Joannopoulos, S. G. Johnson, J. N. Winn, and R. D. Meade, Photonic Crystals (Princeton University Press, 2011) 33. H. J. Lim, H. J. Lim, C. M. Lee, C. M. Lee, B. H. Ahn, B. H. Ahn, Y. H. Lee, and Y. H. Lee, \"Dual rail nanobeam microfiber coupled resonator,\" Optics Express 21, 6724 (2013) 34. M. W. Lee, C. Grillet, C. G. Poulton, C. Monat, C. L. C. Smith, E. Maegi, D. Freeman, S. Madden, B. Luther Davies, and B. J. Eggleton, \"Characterizing photonic crystal waveguides with an expanded k space evanescent coupling technique,\" Optics Express 16, 13800 13808 (2008) 35. M. Winger, T. Volz, G. Tarel, S. Portolan, A. Badolato, K. Hennessy, E. Hu, A. Beveratos, J. Finley, V. Savona, and A. Imamoglu, \"Explanation of Photon Correlations in the Far Off Resonance Optical Emission from a Quantum Dot Cavity System,\" Phys. Rev. Lett. 103, 207403 (2009) 36. A. Laucht, M. Kaniber, A. Mohtashami, N. Hauke, M. Bichler, and J. J. Finley, \"Temporal monitoring of nonresonant feeding of semiconductor nanocavity modes by quantum dot multiexciton transitions,\" Phys. Rev. B 81, 241302 (2010) 37. E. Peter, S. Laurent, J. Bloch, J. Hours, S. Varoutsis, I. Robert Philip, A. Beveratos, A. Lemaitre, A. Cavanna, G. Patriarche, P. Senellart, and D. Martrou, \"Fast radiative quantum dots: From single to multiple photon emission,\" Appl. Phys. Lett. 90, 223118 (2007) 38. E. Stock, W. Unrau, A. Lochmann, J. A. Tofflinger, M. Ozturk, A. I. Toropov, A. K. Bakarov, V. A. Haisler, and D. Bimberg, \"High speed single photon source based on self organized quantum dots,\" Semicond. Sci. Technol. 26, 014003 (2010) 39. S. Mosor, J. Hendrickson, B. C. Richards, J. Sweet, G. Khitrova, H. M. Gibbs, T. Yoshie, A. Scherer, O. B. Shchekin, and D. G. Deppe, \"Scanning a photonic crystal slab nanocavity by condensation of xenon,\" Appl. Phys. Lett. 87, 141105 (2005) 40. A. Rastelli, F. Ding, J. D. Plumhof, S. Kumar, R. Trotta, C. Deneke, A. Malachias, P. Atkinson, E. Zallo, T. Zander, A. Herklotz, R. Singh, V. Krapek, J. R. Schroter, S. Kiravittaya, M. Benyoucef, R. Hafenbrak, K. D. Jons, D. J. Thurmer, D. Grimm, G. Bester, K. Dorr, P. Michler, and O. G. Schmidt, \"Controlling quantum dot emission by", "author_names": [ "", "H -" ], "corpus_id": 46175889, "doc_id": "46175889", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Microfiber microcavity system for efficient single photon", "venue": "", "year": 2016 }, { "abstract": "Silicon nitride is a well established material for photonic devices and integrated circuits. It displays a broad transparency window spanning from the visible to the mid IR and waveguides can be manufactured with low losses. An absence of nonlinear multi photon absorption in the erbium lightwave communications band has enabled various nonlinear optic applications in the past decade. Silicon nitride is a dielectric material whose optical and mechanical properties strongly depend on the deposition conditions. In particular, the optical bandgap can be modified with the gas flow ratio during low pressure chemical vapor deposition (LPCVD) Here we show that this parameter can be controlled in a highly reproducible manner, providing an approach to synthesize the nonlinear Kerr coefficient of the material. This holistic empirical study provides relevant guidelines to optimize the properties of LPCVD silicon nitride waveguides for nonlinear optics applications that rely on the Kerr effect. References and links 1. D. T. Spencer, J. F. Bauters, M. J. R. Heck, and J. E. Bowers, \"Integrated waveguide coupled Si3N4 resonators in the ultrahigh Q regime,\" Optica 1(3) 153 157 (2014) 2. J. F. Bauters, M. J. R. Heck, D. D. John, J. S. Barton, C. M. Bruinink, A. Leinse, R. G. Heideman, D. J. Blumenthal, and J. E. Bowers, \"Planar waveguides with less than 0.1 dB/m propagation loss fabricated with wafer bonding,\" Opt. Express 19(24) 24090 24101 (2011) 3. Purnawirman, J. Sun, T. N. Adam, G. Leake, D. Coolbaugh, J. D. B. Bradley, E. S. Hosseini, and M. R. Watts, \"Cand L band erbium doped waveguide lasers with wafer scale silicon nitride cavities,\" Opt. Lett. 38(11) 1760 1763 (2013) 4. W. D. Sacher, Z. Yong, J. C. Mikkelsen, A. Bois, Y. Yang, J. C. Mak, P. Dumais, D. Goodwill, C. Ma, J. Jeong, E. Bernier, and J. K. Poon, \"Multilayer silicon nitride on silicon integrated photonic platform for 3D photonic circuits,\" Conference on Lasers and Electro Optics JTH4C.3 (2016) 5. A. Z. Subramanian, P. Neutens, A. Dhakal, R. Jansen, T. Claes, X. Rottenberg, F. Peyskens, S. Selvaraja, P. Helin, B. Du Bois, K. Leyssens, S. Severi, P. Deshpande, R. Baets, and P. Van Dorpe, \"Low loss singlemode PECVD silicon nitride photonic wire waveguides for 532 900 nm wavelength window fabricated within a CMOS pilot line,\" IEEE Photonics J. 5(6) 2202809 (2013) 6. S. Romero Garcia, F. Merget, F. Zhong, H. Finkelstein, and J. Witzens, \"Silicon nitride CMOS compatible platform for integrated photonics applications at visible wavelengths,\" Opt. Express 21(12) 14036 14046 (2013) 7. R. Heiderman, M. Hoekman, and E. Schreuder, \"TriPleX based integrated optical ring resonators for lab on a chip and environmental detection,\" IEEE J. Quantum Electron. 18(5) 1583 1596 (2012) 8. K. Ikeda, R. E. Saperstein, N. Alic, and Y. Fainman, \"Thermal and Kerr nonlinear properties of plasma deposited silicon nitride/ silicon dioxide waveguides,\" Opt. Express 16(17) 12987 12994 (2008) 9. J. S. Levy, A. Gondarenko, M. A. Foster, A. C. Turner Foster, A. L. Gaeta, and M. Lipson, \"CMOS compatible multiple wavelength oscillator for on chip optical interconnects,\" Nature Phot. 4, 37 40 (2010) 10. T. Herr, K. Hartinger, J. Riemensberger, C. Y.Wang, E. Gavartin, R. Holzwarth,M. L. Gorodetsky, and T. J. Kippenberg, \"Universal formation dynamics and noise of Kerr frequency combs in microresonators,\" Nature Phot. 6, 480 487 (2012) 11. F. Ferdous, H. Miao, D. E. Leaird, K. Srinivasan, J. Wang, L. Chen, L. T. Varghese, and A. M. Weiner, \"Spectral line by line pulse shaping of an on chip microresonator frequency comb,\" Nature Phot. 5, 770 776 (2011) 12. R. Halir, Y. Okawachi, J. S. Levy, M. A. Foster, M. Lipson, and A. L. Gaeta, \"Ultrabroadband supercontinuum generation in a CMOS compatible platform,\" Opt. Lett. 37(10) 1685 1687 (2012) 13. J. P. Epping, T. Hellwig, M. Hoekman, R. Matemann, A. Leinse, R. G. Heideman, A. van Rees, P. J. M. van der Slot, C. J. Lee, C. Fallnich, and K. J. Boller, \"On chip visible to infrared supercontinuum generation with more than 495 THz spectral bandwidth,\" Opt. Express 23(15) 19596 19604 (2017) ar X iv :1 70 3. 05 58 6v 1 ph ys ic s. op tic s] 1 6 M ar 2 01 7 14. C. J. Kruckel, V. Torres Company, P. A. Andrekson, D. T. Spencer, J. F. Bauters, M. J. R. Heck, and J. E. Bowers, \"Continuous wave pumped wavelength conversion in low loss silicon nitride waveguides,\" Opt. Lett. 40(6) 875 878 (2015) 15. Q. Li, M. Davanco, and K. Srinivasan, \"Efficient and low noise single photon level frequency conversion interfaces using silicon nanophotonics,\" Nature Phot. 10, 406 414 (2016) 16. T. Makino, \"Composition and structure control by source gas ratio in LPCVD SiNx,\" J. Electrochem. Soc. Solid state science and technology 130(2) 450 455 (1983) 17. J. G. E. Gardeniers, H. A. C. Tilmans, and C. C. G. Visser, \"LPCVD silicon rich silicon nitride films for applications in micromechanics, studied with statistical experimental design,\" J. Vac. Sci. Technol. A 14(5) 2879 2892 (1996) 18. Y. Toivola, J. Thurn, R. F. Cook, G. Cibuzar, and K. Roberts, \"Influence of deposition conditions on mechanical properties of low pressure chemical vapor deposited low stress silicon nitride films,\" Journ. of Appl. Sc. 94(10) 6915 6922 (2003) 19. J. M. Olson, \"Analysis of LPCVD process conditions for the deposition of low stress silicon nitride. Part I: preliminary LPCVD experiments,\" Mat. Sc. in Semicond. Proc. 5(1) 51 60 (2002) 20. C. J. Kruckel, A. Fulop, T. Klintberg, J. Bengtsson, P. A. Andrekson, and V. Torres Company, \"Linear and nonlinear characterization of low stress high confinement silicon rich nitride waveguides,\" Opt. Express 23(20) 25828 25837 (2015) 21. C. Lacava, S. Stankovic, A. Z. Khokhar, T. Dominguez, F. Y. Gardes, G. T. Reed, D. J. Richardson, and P. Petropoulos, \"Si rich silicon nitride for nonlinear signal processing applications,\" Scient. Rep. 7(22) 1 13 (2017) 22. K. J. A. Ooi, D. K. T. Ng, T. Wang, A. K. L. Chee, S. K. Ng, Q. Wang, L. K. Ang, A. M. Agrawal, L. C. Kimerling, and D. T. H. Tan, \"Pushing the limits of CMOS optical parametric amplifiers with USRN:Si7N3 above the two photon absorption edge,\" Nature Comm. 8(13878) (2017) 23. F. Ferdous, H. Miao, D. E. Leaird, K. Srinivasan, J. Wang, L. Chen, L. T. Varghese, and A. M. Weiner, \"Spectral line by line pulse shaping of an on chip microresonator frequency comb,\" Nature Phot. 5, 770 776 (2011) 24. M. H. P. Pfeiffer, A. Kordts, V. Brasch, M. Zervas, M. Geiselman, J. D. Jost, and T. J. Kippenberg, \"Photonic Damascene process for integrated high Q microresonator based nonlinear photonics,\" Optica 3(1) 20 25 (2016) 25. K. Hyun Nam, I. H. Park, and S. Hwan Ko, \"Patterning by controlled cracking,\" Nature 485, 221 224 (2012) 26. K. Luke, Y. Okawachi, M. R. E. Lamont, A. L. Gaeta, and M. Lipson, \"Broadband mid infrared frequency comb generation in a Si3N4 microresonator,\" Opt. Lett. 40(21) 4823 4826 (2015) 27. Y. Xuan, Y. Liu, L. T. Varghese, A. J. Metcalf, X. Xue, P. H. Wang, K. Han, J. A. Jaramillo Villegas, A. Al Noman, C. Wang, S. Kim, Y. J. Lee, B. Niu, L. Fan, J. Wang, D. E. Leaird, A. M. Weiner, and M. Qi, \"High Q silicon nitride microresonators exhibiting low power frequency comb initiation,\" Optica 3(11) 1171 1180 (2016) 28. G. E. Jellison Jr. and F. A. Modine, \"Parametrization of the optical functions of amorphous materials in the interband region,\" Appl. Phys. Lett. 69(3) 371 373 (1996) 29. K. N. Andersen, W. E. Svendsen, T. Stimpel Lindner, T.Sulima, and H. Baumgaertner, \"Annealing and deposition effects of the chemical composition of silicon rich nitride,\" Appl. Surf. Sc. 243(1 4) 401 408 (2005) 30. M. A. Foster, A. C. Turner, R. Salem, M. Lipson, and A. L. Gaeta, \"Broad band continuous wave parametric wavelength conversion in silicon nanowaveguides,\" Opt. Express 15(20) 12949 12958 (2007) 31. J.M. Chavez Boggio, D. Bodenmoller, T. Fremberg, R. Haynes,M.M. Roth, R. Eisermann,M. Lisker, L. Zimmermann, and M. Bohm, \"Dispersion engineered silicon nitride waveguides by geometrical and refractive index optimization,\" J. Opt. Soc. Am. B 31(11) 2846 2857 (2014) 32. A. Boskovic, S. V. Chernikov, J. R. Taylor, L. Gruner Nielsen, and O. A. Levring, \"Direct continuous wave measurement of n2 in various types of telecommunication fiber at 1.55 mm,\" Opt. Lett. 21(24) 1966 1968 (1996) 33. X. Liu, M. Pu, B. Zhou, C. J. Kruckel, A. Fulop, V. Torres Company, andM. Bache, \"Octave spanning supercontinuum generation in a silicon rich nitride waveguide,\" Opt. Lett. 41(12) 2719 2722 (2016) 34. M. Sheik Bahae, D. J. Hagan, and E. W. Van Stryland, \"Dispersion and band gap scaling of the electronic Kerr effect in solids associated with two photon absorption,\" Phys. Rev. Lett. 65(1) 96 99 (1990) 35. K. Tanaka, and A. Saitoh, \"Optical nonlinearity in glasses: the origin and photo excitation effects,\" J. Mater Sci: Mater Electron 18(Suppl 1) 75 79 (2007) 36. J. Leuthold, C. Koos, and W. Freude, \"Nonlinear silicon photonics,\" Nature Phot. 4, 535 544 (2010) 37. A. D. Bristow, N. Rotenberg, and H. M. van Driel, \"Two photon absorption and Kerr coefficients of silicon for 850 2200 nm,\" Appl. Phys. Lett. 90, 191104 3 (2007) 38. R. H. Stolen, and C. Lin, \"Self phase modulation in silica optical fibers,\" Phys. Rev. A 17(4) 1448 1453 (1978) 39. G. L. Tan, M. F. Lemon, D. J. Jones, and R. H. French, \"Optical properties and London dispersion interaction of amorphous and crystalline SiO2 determined by vacuum ultraviolet spectroscopy and spectroscopic ellipsometry,\" Phys. Rev. B 72(20) 205117 10 (2005) 40. K. Narayanan, and S. F. Preble, \"Optical nonlinearities in hydrogenated amorphous silicon waveguides,\" Opt. Express 18(9) 8998 9005 (2010) 41. B. Kuyken, H. Ji, S. Clemmen, S. K. Selvaraja, H. Hu, M. Pu, M. Galili, P. Jeppesen, G. Morthier, S. Massar, L. K. Oxenlowe, G. Roelkens, and R. Baets, \"Nonlinear properties of and nonlinear processing in hydrogenated amorphous silicon wavegui", "author_names": [ "", "K J" ], "corpus_id": 199519708, "doc_id": "199519708", "n_citations": 3, "n_key_citations": 2, "score": 0, "title": "Optical bandgap engineering in nonlinear silicon nitride waveguides", "venue": "", "year": 2018 }, { "abstract": "We report results on the possibility of subwavelength coherent control of light in coupled plasmonic nanoresonators on dielectric waveguides. Our calculations show that subwavelength regions of the plasmonic structure, spatially separated by a few nanometers, can be individually addressed by controlling the relative phase of the injected fields. We also show the complementary possibility to efficiently inject a guided mode into a planar dielectric waveguide by collecting the radiation emitted by wire like and/or point like sources, placed into the resonators. For example, this configuration provides a useful and powerful tool to control the emission of the localized sources such as stripes of fluorescent molecules or quantum dots placed in the gaps between the plasmonic structures. Possible applications of the considered study include plasmonic logic gates, integrated sensors for single molecule fluorescence, and ready to use devices based on plasmonic single photon sources.", "author_names": [ "Salvatore Tuccio", "Marco Centini", "A Benedetti", "Concita Sibilia" ], "corpus_id": 121778679, "doc_id": "121778679", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Subwavelength coherent control and coupling of light in plasmonic nanoresonators on dielectric waveguides", "venue": "", "year": 2013 }, { "abstract": "Quantum plasmonics opens the option to integrate complex quantum optical circuitry onto chip scale devices. In the past, often external light sources were used and nonclassical light was coupled in and out of plasmonic structures, such as hole arrays or waveguide structures. Another option to launch single plasmonic excitations is the coupling of single emitters in the direct proximity of, e.g. a silver or gold nanostructure. Here, we present our attempts to integrate the research of single emitters with wet chemically grown silver nanowires. The emitters of choice are single organic dye molecules under cryogenic conditions, which are known to act as high brightness and extremely narrow band single photon sources. Another advantage is their high optical nonlinearity, such that they might mediate photon photon interactions on the nanoscale. We report on the coupling of a single molecule fluorescence emission through the wire over the length of several wavelengths. The transmission of coherently emitted ph.", "author_names": [ "Ilja Gerhardt", "Bernhard Grotz", "Petr Siyushev", "Jorg Wrachtrup" ], "corpus_id": 125465693, "doc_id": "125465693", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Coherent interaction of single molecules and plasmonic nanowires", "venue": "", "year": 2017 }, { "abstract": "Recent breakthroughs in solid state photonic quantum technologies enable generating and detecting single photons with near unity efficiency as required for a range of photonic quantum technologies. The lack of methods to simultaneously generate and control photons within the same chip, however, has formed a main obstacle to achieving efficient multi qubit gates and to harness the advantages of chip scale quantum photonics. Here we propose and demonstrate an integrated voltage controlled phase shifter based on the electro optic effect in suspended photonic waveguides with embedded quantum emitters. The phase control allows building a compact Mach Zehnder interferometer with two orthogonal arms, taking advantage of the anisotropic electro optic response in gallium arsenide. Photons emitted by single self assembled quantum dots can be actively routed into the two outputs of the interferometer. These results, together with the observed sub microsecond response time, constitute a significant step towards chip scale single photon source de multiplexing, fiber loop boson sampling, and linear optical quantum computing. (c) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement OCIS codes: (230.5590) Quantum well, wire and dot devices; (230.3120) Integrated optics devices; (230.2090) Electro optical devices; (250.7360) Waveguide modulators. References and links 1. J. L. O'Brien, A. Furusawa, and J. Vuckovic, \"Photonic quantum technologies,\" Nat. Photonics 3(12) 687 695 (2009) 2. P. Lodahl, S. Mahmoodian, and S. Stobbe, \"Interfacing single photons and single quantum dots with photonic nanostructures,\" Rev. Mod. Phys. 87(2) 347 400 (2015) 3. C. P. Dietrich, A. Fiore, M. G. Thompson, M. Kamp, and S. Hofling, \"GaAs integrated quantum photonics: Towards compact and multi functional quantum photonic integrated circuits,\" Laser Photonics Rev. 10(6) 870 894 (2016) 4. M. Arcari, I. Sollner, A. Javadi, S. Lindskov Hansen, S. Mahmoodian, J. Liu, H. Thyrrestrup, E. H. Lee, J. D. Song, S. Stobbe, and P. Lodahl, \"Near unity coupling efficiency of a quantum emitter to a photonic crystal waveguide,\" Phys. Rev. Lett. 113, 093603 (2014) 5. J. P. Sprengers, A. Gaggero, D. Sahin, S. Jahanmirinejad, G. Frucci, F. Mattioli, R. Leoni, J. Beetz, M. Lermer, M. Kamp, S. Hofling, R. Sanjines, and A. Fiore, \"Waveguide superconducting single photon detectors for integrated quantum photonic circuits,\" Appl. Phys. Lett. 99, 181110 (2011) 6. F. Marsili, V. B. Verma, J. A. Stern, S. Harrington, A. E. Lita, T. Gerrits, I. Vayshenker, B. Baek, M. D. Shaw, R. P. Mirin, and S. W. Nam, \"Detecting single infrared photons with 93% system efficiency,\" Nat. Photonics 7(3) 210 214 (2013) 7. E. Knill, R. Laflamme, and G. J. Milburn, \"A scheme for efficient quantum computation with linear optics,\" Nature 409(6816) 46 52 (2001) 8. H. Wang, Y. He, Y. H. Li, Z. E. Su, B. Li, H. L. Huang, X. Ding, M. C. Chen, C. Liu, J. Qin, J. P. Li, Y. M. He, C. Schneider, M. Kamp, C. Z. Peng, S. Hofling, C. Y. Lu, and J. W. Pan, \"High efficiency multiphoton boson sampling,\" Nat. Photonics 11, 361 365 (2017) 9. K. R. Motes, A. Gilchrist, J. P. Dowling, and P. P. Rohde, \"Scalable boson sampling with time bin encoding using a loop based architecture,\" Phys. Rev. Lett. 113, 120501 (2014) 10. F. Lenzini, B. Haylock, J. C. Loredo, R. A. Abrahao, N. A. Zakaria, S. Kasture, I. Sagnes, A. Lemaitre, H. P. Phan, D. V. Dao, P. Senellart, M. P. Almeida, A. G. White, and M. Lobino, \"Active demultiplexing of single photons from a solid state source,\" Laser Photonics Rev. 11, 1600297 (2017) 11. N. Somaschi, V. Giesz, L. D. Santis, J. C. Loredo, M. P. Almeida, G. Hornecker, S. L. Portalupi, T. Grange, C. Anton, J. Demory, C. Gomez, I. Sagnes, N. D. Lanzillotti Kimura, A. Lemaitre, A. Auffeves, A. G. White, L. Lanco, and P. Senellart, \"Near optimal single photon sources in the solid state,\" Nat. Photonics 10(5) 340 345 (2016) 12. G. Kirsanske, H. Thyrrestrup, R. S. Daveau, C. L. Dreessen, T. Pregnolato, L. Midolo, P. Tighineanu, A. Javadi, S. Stobbe, R. Schott, A. Ludwig, A. D. Wieck, S. I. Park, J. D. Song, A. V. Kuhlmann, I. Sollner, M. C. Lobl, R. J. Warburton, and P. Lodahl, \"Indistinguishable and efficient single photons from a quantum dot in a planar nanobeam waveguide,\" Phys. Rev. B 96, 165306 (2017) 13. C. Bentham, I. E. Itskevich, R. J. Coles, B. Royall, E. Clarke, J. O'Hara, N. Prtljaga, A. M. Fox, M. S. Skolnick, and L. R. Wilson, \"On chip electrically controlled routing of photons from a single quantum dot,\" Appl. Phys. Lett. 106, 221101 (2015) 14. I. J. Luxmoore, N. A. Wasley, A. J. Ramsay, A. C. T. Thijssen, R. Oulton, M. Hugues, A. M. Fox, and M. S. Skolnick, \"Optical control of the emission direction of a quantum dot,\" Appl. Phys. Lett. 103, 241102 (2013) 15. I. Sollner, S. Mahmoodian, S. L. Hansen, L. Midolo, A. Javadi, G. Kirsanske, T. Pregnolato, H. El Ella, E. H. Lee, J. D. Song, S. Stobbe, and P. Lodahl, \"Deterministic photon emitter coupling in chiral photonic circuits,\" Nat. Nanotechnol. 10, 775 778 (2015) 16. J. W. Silverstone, D. Bonneau, K. Ohira, N. Suzuki, H. Yoshida, N. Iizuka, M. Ezaki, C. M. Natarajan, M. G. Tanner, R. H. Hadfield, V. Zwiller, G. D. Marshall, J. G. Rarity, J. L. O'Brien, and M. G. Thompson, \"On chip quantum interference between silicon photon pair sources,\" Nat. Photonics 8(2) 104 108 (2014) 17. M. Poot and H. X. Tang, \"Broadband nanoelectromechanical phase shifting of light on a chip,\" Appl. Phys. Lett. 104, 061101 (2014) 18. J. Wang, A. Santamato, P. Jiang, D. Bonneau, E. Engin, J. W. Silverstone, M. Lermer, J. Beetz, M. Kamp, S. Hofling, M. G. Tanner, C. M. Natarajan, R. H. Hadfield, S. N. Dorenbos, V. Zwiller, J. L. O'Brien, and M. G. Thompson, \"Gallium arsenide (GaAs) quantum photonic waveguide circuits,\" Opt. Commun. 327, 49 55 (2014) 19. H. Jin, F. M. Liu, P. Xu, J. L. Xia, M. L. Zhong, Y. Yuan, J. W. Zhou, Y. X. Gong, W. Wang, and S. N. Zhu, \"On chip generation and manipulation of entangled photons based on reconfigurable Lithium Niobate waveguide circuits,\" Phys. Rev. Lett. 113, 103601 (2014) 20. P. R. Sharapova, K. H. Luo, H. Herrmann, M. Reichelt, T. Meier, and C. Silberhorn, \"Generation and active manipulation of qubits in LiNbO3 based integrated circuits,\" https:/arxiv.org/abs/1704.03769. 21. K. Liu, C. R. Ye, S. Khan, and V. J. Sorger, \"Review and perspective on ultrafast wavelength size electro optic modulators,\" Laser Photonics Rev. 9(2) 172 194 (2015) 22. J. C. Campbell, F. A. Blum, D. W. Shaw, and K. L. Lawley, \"GaAs electro optic directional coupler switch,\" Appl. Phys. Lett. 27(4) 202 205 (1975) 23. A. J. Bennett, R. B. Patel, J. Skiba Szymanska, C. A. Nicoll, I. Farrer, D. A. Ritchie, and A. J. Shields, \"Giant Stark effect in the emission of single semiconductor quantum dots,\" Appl. Phys. Lett. 97, 031104 (2010) 24. S. G. Carter, T. M. Sweeney, M. Kim, C. S. Kim, D. Solenov, S. E. Economou, T. L. Reinecke, L. Yang, A. S. Bracker, and D. Gammon, \"Quantum control of a spin qubit coupled to a photonic crystal cavity,\" Nat. Photonics 7(4) 329 334 (2013) 25. R. Syms and J. Cozens, Optical Guided Waves and Devices (McGraw Hill, 1992) 26. S. S. Lee, R. V. Ramaswamy, and V. S. Sundaram, \"Analysis and design of high speed high efficiency GaAs AlGaAs double heterostructure waveguide phase modulator,\" IEEE J. Quantum Elect. 27(3) 726 736 (1991) 27. C. Berseth, C. Wuethrich, and F. K. Reinhart, \"The electro optic coefficients of GaAs: Measurements at 1.32 and 1.52 mm and study of their dispersion between 0.9 and 10 mm,\" J. Appl. Phys. 71(6) 2821 2825 (1992) 28. H. C. Casey, D. D. Sell, and K. W. Wecht, \"Concentration dependence of the absorption coefficient for nand p type GaAs between 1.3 and 1.6 eV,\" J. Appl. Phys. 46(1) 250 257 (1975) 29. G. E. Stillman, C. M. Wolfe, C. O. Bozler, and J. A. Rossi, \"Electroabsorption in GaAs and its application to waveguide detectors and modulators,\" Appl. Phys. Lett. 28(9) 544 546 (1976) 30. Y. A. Vlasov, M. O'Boyle, H. F. Hamann, and S. J. McNab, \"Active control of slow light on a chip with photonic crystal waveguides,\" Nature 438(7064) 65 69 (2005) 31. L. B. Soldano and E. C. M. Pennings, \"Optical multi mode interference devices based on self imaging: principles and applications,\" J. Lightwave Technol. 13(4) 615 627 (1995) 32. G. Simpson, \"A generalized n port cascade connection,\" in Microwave Symposium Digest, 1981 IEEE MTT S International, (IEEE, 1981) pp. 507 509. 33. L. Midolo, T. Pregnolato, G. Kirsanske, and S. Stobbe, \"Soft mask fabrication of gallium arsenide nanomembranes for integrated quantum photonics,\" Nanotechnology 26, 484002 (2015) 34. D. Press, K. De Greve, P. L. McMahon, T. D. Ladd, B. Friess, C. Schneider, M. Kamp, S. Hofling, A. Forchel, and Y. Yamamoto, \"Ultrafast optical spin echo in a single quantum dot,\" Nat. Photonics 4(6) 367 370 (2010) 35. F. Pagliano, Y. Cho, T. Xia, F. v. Otten, R. Johne, and A. Fiore, \"Dynamically controlling the emission of single excitons in photonic crystal cavities,\" Nat. Commun. 5, 5786 (2014) 36. D. Parrain, C. Baker, G. Wang, B. Guha, E. Gil Santos, A. Lemaitre, P. Senellart, G. Leo, S. Ducci, and I. Favero, \"Origin of optical losses in gallium arsenide disk whispering gallery resonators,\" Opt. Express 23(15) 19656 19672 (2015) 37. C. P. Michael, K. Srinivasan, T. J. Johnson, and O. Painter, \"Wavelengthand material dependent absorption in GaAs and AlGaAs microcavities,\" Appl. Phys. Lett. 90, 051108 (2007) 38. L. M. Duan and H. J. Kimble, \"Scalable photonic quantum computation through cavity assisted interactions,\" Phys. Rev. Lett. 92, 127902 (2004) 39. L. Sapienza, M. Davanco, A. Badolato, and K. Srinivasan, \"Nanoscale optical positioning of single quantum dots for bright and pure single photon emission,\" Nat. Commun. 6, 7833 (2015)", "author_names": [ "", "H L" ], "corpus_id": 39313547, "doc_id": "39313547", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Electro optic routing of photons from a single quantum dot in photonic integrated circuits Midolo,", "venue": "", "year": 2018 }, { "abstract": "We demonstrate single photon counting of terahertz (THz) waves transmitted from a local THz point source through a coplanar two wire waveguide on a GaAs/AlGaAs single heterostructure crystal. In the electrically driven all in one chip, quantum Hall edge transport is used to achieve a noiseless injection current for a monochromatic point source of THz fields. The local THz fields are coupled to a coplanar two wire metal waveguide and transmitted over a macroscopic scale greater than the wavelength (38 mm in GaAs) THz waves propagating on the waveguide are counted as individual photons by a quantum dot single electron transistor on the same chip. Photon counting on integrated high frequency circuits will open the possibilities for on chip quantum optical experiments.", "author_names": [ "Kenji Ikushima", "Atsushi Ito", "Shun Okano" ], "corpus_id": 59354391, "doc_id": "59354391", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Generation, transmission, and detection of terahertz photons on an electrically driven single chip", "venue": "", "year": 2014 }, { "abstract": "The development of new photonic materials that combine diverse optical capabilities is needed to boost the integration of different quantum and classical components within the same chip. Amongst all candidates, the superior optical properties of cubic silicon carbide (3C SiC) could be merged with its crystalline point defects, enabling single photon generation, manipulation and light matter interaction on a single device. The development of photonics devices in SiC has been limited by the presence of the silicon substrate, over which thin crystalline films are heteroepitaxially grown. By employing a novel approach in the material fabrication, we demonstrate grating couplers with coupling efficiency reaching 6 dB, sub mm waveguides and high intrinsic quality factor (up to 24,000) ring resonators. These components are the basis for linear optical networks and essential for developing a wide range of photonics component for non linear and quantum optics. c (c) 2017 Optical Society of America OCIS codes: (130.3120) Integrated optics devices; (130.3130) Integrated optics materials; (130.4310) Nonlinear. References and links 1. J. L. O'Brien, A. Furusawa, and J. Vuckovic, \"Photonic quantum technologies,\" Nat. Photonics 3, 687 695 (2009) 2. M. Davanco, J. Liu, L. Sapienza, C. Z. Zhang, J. V. D. M. Cardoso, V. Verma, R. Mirin, S. W. Nam, L. Liu, and K. Srinivasan, \"A heterogeneous iii v/silicon integration platform for on chip quantum photonic circuits with single quantum dot devices,\" arXiv preprint arXiv:1611.07654 (2016) 3. F. De Leonardis, R. A. Soref, and V. M. Passaro, \"Dispersion of nonresonant third order nonlinearities in silicon carbide,\" Sci. Rep. 7 (2017) 4. I. Wu and G. Guo, \"Second harmonic generation and linear electro optical coefficients of SiC polytypes and nanotubes,\" Phys. Rev. B 78, 035447 (2008) 5. L. G. Helt, M. Liscidini, and J. E. Sipe, \"How does it scale? comparing quantum and classical nonlinear optical processes in integrated devices,\" J. Opt. Soc. Am. B 29, 2199 2212 (2012) 6. C. A. Husko, A. S. Clark, M. J. Collins, A. De Rossi, S. Combrie, G. Lehoucq, I. H. Rey, T. F. Krauss, C. Xiong, and B. J. Eggleton, \"Multi photon absorption limits to heralded single photon sources,\" Sci. Rep. 3, 3087 (2013) 7. X. Tang, K. G. Irvine, D. Zhang, and M. G. Spencer, \"Linear electro optic effect in cubic silicon carbide,\" Appl. Phys. Lett. 59, 1938 (1991) 8. A. Vonsovici, G. T. Reed, and A. G. Evans, \"b SiC on insulator waveguide structures for modulators and sensor systems,\" Mater. Sci. Semiconductor Processing 3, 367 374 (2000) 9. A. L. Falk, B. B. Buckley, G. Calusine, W. F. Koehl, V. V. Dobrovitski, A. Politi, C. a. Zorman, P. X. L. Feng, and D. D. Awschalom, \"Polytype control of spin qubits in silicon carbide,\" Nat. Commun. 4, 1819 (2013) 10. F. Fuchs, V. a. Soltamov, S. Vath, P. G. Baranov, E. N. Mokhov, G. V. Astakhov, and V. Dyakonov, \"Silicon carbide light emitting diode as a prospective room temperature source for single photons,\" Sci. Rep. 3, 1637 (2013) 11. S. Castelletto, B. C. Johnson, V. Ivady, N. Stavrias, T. Umeda, a. Gali, and T. Ohshima, \"A silicon carbide roomtemperature single photon source,\" Nat. Mater. 13, 151 156 (2014) 12. G. Calusine, A. Politi, and D. D. Awschalom, \"Cavity Enhanced Measurements of Defect Spins in Silicon Carbide,\" Phys. Rev. Appl. 6, 014019 (2016) 13. V. Bratus' R. Melnik, S. Okulov, V. Rodionov, B. Shanina, and M. Smoliy, \"A new spin one defect in cubic SiC,\" Physica B: Condensed Matter 404, 4739 4741 (2009) 14. N. Son, E. Sorman, W. Chen, M. Singh, C. Hallin, O. Kordina, B. Monemar, E. Janzen, and J. Lindstrom, \"Dominant recombination center in electron irradiated 3c sic,\" J. Appl. Phys. 79, 3784 3786 (1996) 15. C. M. Zetterling, ed. Process Technology for Silicon Carbide Devices (Institution of Engineering and Technology, 2002) 16. S. Nishino, H. Suhara, H. Ono, and H. Matsunami, \"Epitaxial growth and electric characteristics of cubic sic on silicon,\" J. Appl. Phys. 61, 4889 4893 (1987) 17. J. Cardenas, M. Yu, Y. Okawachi, C. B. Poitras, R. K. Lau, A. Dutt, A. L. Gaeta, and M. Lipson, \"Optical nonlinearities in high confinement silicon carbide waveguides,\" Opt. Lett. 40, 4138 4141 (2015) 18. M. Bosi, G. Attolini, M. Negri, C. Frigeri, E. Buffagni, C. Ferrari, T. Rimoldi, L. Cristofolini, L. Aversa, R. Tatti, and R. Verucchi, \"Optimization of a buffer layer for cubic silicon carbide growth on silicon substrates,\" J. Crystal Growth 383, 84 94 (2013) Vol. 25, No. 10 15 May 2017 OPTICS EXPRESS 10735 #283329 https:/doi.org/10.1364/OE.25.010735 Journal (c) 2017 Received 13 Jan 2017; revised 10 Mar 2017; accepted 10 Mar 2017; published 1 May 2017 19. R. Anzalone, G. D'arrigo, M. Camarda, C. Locke, S. Saddow, and F. La Via, \"Advanced residual stress analysis and fem simulation on heteroepitaxial 3c sic for mems application,\" Journal of Microelectromechanical Systems 20, 745 752 (2011) 20. Q. Li, M. Davanco, and K. Srinivasan, \"Efficient and low noise single photon level frequency conversion interfaces using silicon nanophotonics,\" Nat. Photonics 10, 406 414 (2016) 21. X. Tang, K. Wongchotigul, and M. G. Spencer, \"Optical waveguide formed by cubic silicon carbide on sapphire substrates,\" Appl. Phys. Lett. 58, 917 (1991) 22. F. Xia, M. Rooks, L. Sekaric, and Y. Vlasov, \"Ultra compact high order ring resonator filters using submicron silicon photonic wires for on chip optical interconnects,\" Opt. Express 15, 11934 11941 (2007) 23. Q. Xu, B. Schmidt, S. Pradhan, and M. Lipson, \"Micrometre scale silicon electro optic modulator,\" Nature 435, 325 327 (2005) 24. Z. Yang, P. Chak, A. D. Bristow, H. M. van Driel, R. Iyer, J. S. Aitchison, A. L. Smirl, and J. E. Sipe, \"Enhanced second harmonic generation in AlGaAs microring resonators,\" Opt. Lett. 32, 826 828 (2007) 25. P. S. Kuo, J. Bravo Abad, and G. S. Solomon, \"Second harmonic generation using quasi phasematching in a gaas whispering gallery mode microcavity,\" Nat. Commun. 5 (2014) 26. X. Lu, J. Y. Lee, P. X. L. Feng, and Q. Lin, \"Silicon carbide microdisk resonator,\" Opt. Lett. 38, 1304 1306 (2013) 27. J. Cardenas, M. Zhang, C. T. Phare, S. Y. Shah, C. B. Poitras, B. Guha, and M. Lipson, \"High q sic microresonators,\" Opt. Express 21, 16882 16887 (2013) 28. T. Shoji, T. Tsuchizawa, T. Watanabe, K. Yamada, and H. Morita, \"Low loss mode size converter from 0.3 mm square si wire waveguides to singlemode fibres,\" Electron. Lett. 38, 1669 1670 (2002) 29. A. Bozzola, L. Carroll, D. Gerace, I. Cristiani, and L. C. Andreani, \"Optimising apodized grating couplers in a pure soi platform to 0.5 db coupling efficiency,\" Opt. Express 23, 16289 16304 (2015) 30. W. S. Zaoui, A. Kunze, W. Vogel, M. Berroth, J. Butschke, F. Letzkus, and J. Burghartz, \"Bridging the gap between optical fibers and silicon photonic integrated circuits,\" Opt. Express 22, 1277 1286 (2014) 31. K. M. Jackson, J. Dunning, C. A. Zorman, M. Mehregany, and W. N. Sharpe, \"Mechanical properties of epitaxial 3c silicon carbide thin films,\" J. Microelectromechanical Systems 14, 664 672 (2005) 32. P. Rabiei, W. Steier, C. Zhang, and L. Dalton, \"Polymer micro ring filters and modulators,\" J. Lightwave Technol. 20, 1968 1975 (2002) 33. G. Calusine, A. Politi, and D. D. Awschalom, \"Silicon carbide photonic crystal cavities with integrated color centers,\" Appl. Phys. Lett. 105, 011123 (2014) 34. S. Yamada, B. S. Song, S. Jeon, J. Upham, Y. Tanaka, T. Asano, and S. Noda, \"Second harmonic generation in a silicon carbide based photonic crystal nanocavity,\" Opt. Lett. 39, 1768 1771 (2014) 35. D. O. Bracher and E. L. Hu, \"Fabrication of HighQ Nanobeam Photonic Crystals in Epitaxially Grown 4H SiC,\" Nano Lett. 15, 6202 6207 (2015) 36. F. Van Laere, T. Claes, J. Schrauwen, S. Scheerlinck, W. Bogaerts, D. Taillaert, L. O'Faolain, D. Van Thourhout, and R. Baets, \"Compact focusing grating couplers for silicon on insulator integrated circuits,\" Photonics Technol. Lett. 19, 1919 1921 (2007)", "author_names": [ "" ], "corpus_id": 203743140, "doc_id": "203743140", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Linear integrated optics in 3C silicon carbide", "venue": "", "year": 2017 }, { "abstract": "We introduce a theoretical formalism to calculate the spontaneous emission rate enhancements (Purcell effect) and propagation mode b factors from a quantum dot in a planar photoniccrystal waveguide. Impressive Purcell factors and broadband enhanced b factors are predicted. c (c) 2007 Optical Society of America OCIS codes:(230.7400) Waveguides, slab; (270.5580) Quantum electrodynamics Confining single quantum dots (QD's) in high index contrast photonic crystals (PC's) has recently became an active area of research, which is largely due to the continued success in the fabrication of such structures. The ability to couple single QD's to nanophotonic materials and photonic dots is not only of fundamental importance but can also lead to novel applications including single photon sources [1] low threshold lasers and optical amplifiers. With regard to enhancing the emission rate of a single photon emitter, it is well established that a modified electromagnetic vacuum of the surrounding environment can have a profound influence on the emission rates of a localized emitter. Therefore, an increase in the local density of states (LDOS) created by a cavity can lead to enhanced spontaneous emission of a single photon through the Purcell effect [2] Since the pioneering works of Yablonovitch [3] and John [4] it is also known that periodic dielectric media such as PC's can create photonic bandgaps that may substantially influence the LDOS that a photon feels. From a practical viewpoint, the planar semiconductor PC's currently show enormous promise since they exhibit large quality factors (Q 10) and very small effective mode volumes Veff 0.05 mm) [5] Indeed PC nanocavities are now facilitating new regimes of cavity QED [6, 7] However, to better exploit the single photon emission potential of QD's in planar PC's, improvements in the microcavity excitation, enhanced cavity coupling and efficient extraction of the emitted photons are all required. While enhanced emission and 'strong coupling' in closed cavitydefect modes are to be expected, less obvious it what can be achieved with a waveguide mode or an open cavitywhere excitation and extraction can be also extremely efficient, and everything can be performed in the planeand fully integrated. Having complete knowledge of the photon emission factor into an optical mode from a single QD is a highly desired property, yet presents a considerable challenge for an open cavity system as one must fully understand photon coupling to all available modes that contribute to a particular frequency. In addition, one needs to determine the LDOS as a function of position. For regular planar waveguiding structures, it has proven useful to separate out the various mode contributions in order to highlight the underlying mechanisms of spontaneous emission [8] Recently, signatures of spontaneous emission enhancement of single QD emission in a PC waveguide have been demonstrated experimentally [9] though the Purcell factors were rather modest since the QD was coupled to a leaky mode with a large effective mode volume. Nevertheless, there is a lot of interesting physics behind this effect, and it also relates to earlier predictions about wire waveguides having a divergent like LDOS [10] In this work, we present a general theoretical formalism with rigorous calculations to study Purcell factors and propagation modeb factors for planar PC waveguides, where the b is defined as the fraction of the emitted light 0 0.1 0.2 0.3 0.4 0.5 180 190 200 210 220 230 k (2p/a) f T H z] (a) Y Y 0 X X 0 Y Y 0 (nm) X X 0 (n m 200 0 200 100 0 100 5 10 15 20 25 30 (c) (b)", "author_names": [ "Stephen H Hughes", "V S C Manga Rao" ], "corpus_id": 45078457, "doc_id": "45078457", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Purcell factors and b factors in photonic crystal waveguides", "venue": "", "year": 2006 } ]

[ { "abstract": "A bottleneck limiting the widespread application of semiconductor nanocrystal solids is their poor conductivity. We report that the conductivity of thin films of n type CdSe nanocrystals increases by many orders of magnitude as the occupation of the first two electronic shells, 1Se and 1Pe, increases, either by potassium or electrochemical doping. Around half filling of the 1Se shell, a peak in the conductivity is observed, indicating shell to shell transport. Introducing conjugated ligands between nanocrystals increases the conductivities of these states to ~10 2 siemens per centimeter.", "author_names": [ "Dong Yu", "Congjun Wang", "Philippe Guyot-Sionnest" ], "corpus_id": 33819795, "doc_id": "33819795", "n_citations": 430, "n_key_citations": 6, "score": 1, "title": "n Type Conducting CdSe Nanocrystal Solids", "venue": "Science", "year": 2003 }, { "abstract": "We present a general synthesis for a family of n type transparent conducting oxide nanocrystals through doping with aliovalent cations. These monodisperse nanocrystals exhibit localized surface plasmon resonances tunable in the mid and near infrared with increasing dopant concentration. We employ a battery of electrical measurements to demonstrate that the plasmonic resonance in isolated particles is consistent with the electronic properties of oxide nanocrystal thin films. Hall and Seebeck measurements show that the particles form degenerately doped n type solids with free electron concentrations in the range of 1019 to 1021 cm 3. These heavily doped oxide nanocrystals are used as the building blocks of conductive, n type thin films with high visible light transparency.", "author_names": [ "Benjamin T Diroll", "Thomas R Gordon", "E Ashley Gaulding", "D R Klein", "Taejong Paik", "Hyeong Jin Yun", "E D Goodwin", "Divij Damodhar", "Cherie R Kagan", "Christopher B Murray" ], "corpus_id": 102321644, "doc_id": "102321644", "n_citations": 33, "n_key_citations": 1, "score": 0, "title": "Synthesis of N Type Plasmonic Oxide Nanocrystals and the Optical and Electrical Characterization of their Transparent Conducting Films", "venue": "", "year": 2014 }, { "abstract": "Electrical 1/f noise is measured in thin films of CdSe, CdSe/CdS, ZnO, HgTe quantum dots and Au nanocrystals. The 1/f noise, normalized per nanoparticle, shows no systematic dependence on the nanoparticle material and the coupling material. However, over 10 orders of magnitude, it correlates well with the nearest neighbor conductance suggesting some universal magnitude of the 1/f noise in these granular conductors. In the hopping regime, the main mechanism of 1/f noise is determined to be mobility fluctuated. In the metallic regime obtained with gold nanoparticle films, the noise drops to a similar level as bulk gold films and with a similar temperature dependence.", "author_names": [ "Heng Liu", "Emmanuel Lhuillier", "Philippe Guyot-Sionnest" ], "corpus_id": 122087265, "doc_id": "122087265", "n_citations": 44, "n_key_citations": 0, "score": 0, "title": "1/f noise in semiconductor and metal nanocrystal solids", "venue": "", "year": 2014 }, { "abstract": "The temperature and electrical field dependent conductivity of n type CdSe nanocrystal thin films is investigated. In the low electrical field regime, the conductivity follows sigma approximately exp( (T(/T)(1/2) in the temperature range 10<T<120 K. At high electrical field, the conductivity is strongly field dependent. At 4 K, the conductance increases by 8 orders of magnitude over one decade of bias. At a very high field, conductivity is temperature independent with sigma approximately exp( (E(/E)(1/2) The complete behavior is very well described by variable range hopping with a Coulomb gap.", "author_names": [ "Dong Yu", "Congjun Wang", "Brian L Wehrenberg", "Philippe Guyot-Sionnest" ], "corpus_id": 10565090, "doc_id": "10565090", "n_citations": 296, "n_key_citations": 5, "score": 0, "title": "Variable range hopping conduction in semiconductor nanocrystal solids.", "venue": "Physical review letters", "year": 2004 }, { "abstract": "Submitted for the MAR05 Meeting of The American Physical Society Electron transport of n type semiconductor nanocrystal thin films DONG YU, CONGJUN WANG, BRIAN WEHRENBERG, PHILIPPE GUYOT SIONNEST, JAMES FRANK INSTITUTE, UNIVERSITY OF CHICAGO TEAM The conductivity of thin films of n type colloidal CdSe nanocrystals increases by up to 12 orders of magnitude as the occupation of the first two electronic shells 1Se and 1Pe increases, either by potassium or electrochemical doping. [D. Yu, C. Wang, P. Guyot Sionnest, Science 300, 1277 (2003) In the low electrical field regime, the conductivity follows s exp( (T /T )1/2) in the temperature range 10K<T<120K. At higher electrical field, the conductivity becomes strongly field dependent. At 4K, the conductance increases by eight orders of magnitude over one decade of bias. At extremely high field conductivity becomes temperature independent, where s exp( (E*/E)1/2) The conduction behavior follows Efros Shklovskii's variable range hopping model with Coulomb gap very well and the parameters determined by experiment agree well with the theoretical prediction. [D. Yu, C. Wang, B. Wehrenberg, P. GuyotSionnest, Phys. Rev. Lett. 92, 216802 (2004) Our current interest is to dope magnetic impurities like Mn2+ inside the NCs. The doped magnetic spins provide strong local magnetic field and large magnetoresistive effect is expected.", "author_names": [ "Dong Yu", "Congjun Wang", "Brian L Wehrenberg", "Philippe Guyot-Sionnest" ], "corpus_id": 100604670, "doc_id": "100604670", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Electron transport of n type semiconductor nanocrystal thin films", "venue": "", "year": 2005 }, { "abstract": "Biomolecules labeled with luminescent colloidal semiconductor quantum dots (QDs) have potential for use in numerous applications, including fluoro immunoassays and biological imaging. QD labels exhibit size tunable narrow band luminescent emission and high resistance to photodegradation. They also exhibit efficient Forster energy transfer between neighboring QDs of different sizes and their emission is readily quenched by bound fluorescent dyes. In this paper, we describe preliminary results aimed at defining conditions for the design and preparation of nanoscale QD bio conjugate sensors based on fluorescence quenching. We envision building sensor assemblies that employ quantum dots linked with dye labeled biological receptors that utilize donor acceptor energy transfer between QDs and receptors for conducting recognition based assays. In particular, we report the effects of varying the concentration of energy acceptors bound to nanocrystal surfaces under both soluble and solid phase conditions on quenching phenomena.", "author_names": [ "Phan T Tran", "Ellen R Goldman", "George P Anderson", "J Matthew Mauro", "Hedi Mattoussi" ], "corpus_id": 3016710, "doc_id": "3016710", "n_citations": 104, "n_key_citations": 1, "score": 0, "title": "Use of Luminescent CdSe ZnS Nanocrystal Bioconjugates in Quantum Dot Based Nanosensors", "venue": "", "year": 2002 }, { "abstract": "In order to deposit colloidal nanocrystals on different substrates, a large variety of methodologies have been developed, such as dipcoating, spin coating, or spray coating. The deposition of CdSe/CdS core shell nanorods (NRs) with a conventional office printer onto conducting tin doped indium oxide glass surfaces is presented. This involves the preparation of water based inks containing the NRs. To improve the connection between the CdSe/CdS NRs and the underlying substrates, the glass surfaces were modified by means of silanes. Homogeneous films were obtained by consecutively printing several layers of CdSe/CdS NRs.", "author_names": [ "Franziska Lubkemann", "Ralf Anselmann", "Torben Kodanek", "Nadja C Bigall" ], "corpus_id": 100524314, "doc_id": "100524314", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Inkjet Printing of Aqueous Photoluminescent CdSe/CdS Nanorods on Solid Substrates", "venue": "", "year": 2017 }, { "abstract": "Al and In doped CdSe nanocrystals were synthesized using a three part core shell synthesis. CdSe core nanocrystals were first prepared, then allowed to react with dopant precursors in the presence of weakly binding ligands, and finally overcoated with an additional shell of CdSe. The addition of Al dopants quickened shell overgrowth and led to more monodisperse nanocrystals while the addition of In dopants produced more polydisperse particles, as seen by absorption spectroscopy. Elemental analysis combined with chemical etching revealed the dopants were inside the particles and solid state 27Al nuclear magnetic resonance (NMR) spectra indicated that the Al impurities were well dispersed. When the Al doped nanocrystals were processed into thin film transistors, enhanced n type transport was observed with a rise in the Fermi level compared to undoped particles.", "author_names": [ "Andrew W Wills", "Moon-Sung Kang", "Katherine M Wentz", "Sophia E Hayes", "Ayaskanta Sahu", "Wayne L Gladfelter", "David J Norris" ], "corpus_id": 97575286, "doc_id": "97575286", "n_citations": 27, "n_key_citations": 0, "score": 0, "title": "Synthesis and characterization of Al and In doped CdSe nanocrystals", "venue": "", "year": 2012 }, { "abstract": "CdSe nanorods (NRs) with an average length of 120 nm were prepared by a solvothermal process and associated to TiO2 nanoparticles (Aeroxide(r) P25) by annealing at 300 degC for 1 h. The content of CdSe NRs in CdSe/TiO2 composites was varied from 0.5 to 5 wt The CdSe/TiO2 heterostructured materials were characterized by XRD, TEM, SEM, XPS, UV visible spectroscopy and Raman spectroscopy. TEM images and XRD patterns show that CdSe NRs with wurtzite structure are associated to TiO2 particles. The UV visible spectra demonstrate that the narrow bandgap of CdSe NRs serves to increase the photoresponse of CdSe/TiO2 composites until 725 nm. The CdSe (2 wt /TiO2 composite exhibits the highest photocatalytic activity for the degradation of rhodamine B in aqueous solution under simulated sunlight or visible light irradiation. The enhancement in photocatalytic activity likely originates from CdSe sensitization of TiO2 and the heterojunction between these materials which facilitates electron transfer from CdSe to TiO2. Due to its high stability (up to ten reuses without any significant loss in activity) the CdSe/TiO2 heterostructured catalysts show high potential for real water decontamination. Introduction The development of efficient photocatalysts to address environmental and energy needs, such as degradation of harmful organic compounds in water and in the air or the conversion of solar energy to chemical energy, for example, via water splitting to produce hydrogen, is the topic of numerous current research projects. Titanium dioxide (TiO2) has been widely inBeilstein J. Nanotechnol. 2017, 8, 2741 2752. 2742 vestigated over the last three decades and has been demonstrated to be of high potential [1,2] However, TiO2 suffers from two main drawbacks. First, due to its wide bandgap (Eg 3.2 and 3.0 eV for anatase and rutile, respectively) TiO2 can only be activated by light with a wavelength of less than 390 nm to trigger the electron hole separation. Second, TiO2 exhibits a low quantum efficiency due to the fast recombination of photogenerated charge carriers (electrons and holes) To address these problems, a number of studies have been devoted to the improvement of light absorption and charge separation by hybridizing TiO2 with narrow bandgap semiconductors, doping with metal or nonmetal elements, association with noble metal particles, or constructing heterojunctions between TiO2 and graphene based materials or carbon nitride (C3N4) acting as electron transport materials [3 5] All of these strategies have the common goal of decreasing the charge carrier recombination rate by increasing the spatial charge separation. The interfacial electron transfer between two semiconductors has gained significant interest because the heterojunction improves both the optical absorption in the visible range and the charge separation yield and thus the charge carrier lifetime [3 8] The photocatalytic activity is enhanced because oxidation of water by holes and reduction of oxygen by electrons are retained at two different sites. Recently, many groups demonstrated that the creation of a heterojunction between TiO2 and CdS, CdSe or alloyed CdSeS nanoparticles allows the optical absorption of TiO2 to be extended into the visible light range and increases the photoconversion efficiency by improving the charge transfer [9 37] CdSe is one of the most commonly used semiconductors due to its narrow bandgap (1.7 eV) and its band energies are located at relatively low potential. Despite the large number of reports describing the sensitization of TiO2 (used in the form of spherical particles, films, wires, tubes, etc. with CdSe nanocrystals (generally quantum dots or spherical nanoclusters) [9 37] very little attention has been devoted to the influence of CdSe crystal morphology on the photocatalytic activity of the CdSe/TiO2 heterostructured photocatalysts. CdSe nanorods (NRs) and wires are of high interest for use as sensitizers for photocatalytic applications due to their high surface area, higher optical absorption cross section (as compared to spherical particles) and easier charge carrier separation [38] Only a couple of reports describe the association of CdSe NRs with TiO2. Luo et al. used chemical vapor deposition to associate CdS, CdSe or CdSeS rods to TiO2 NRs arrays and demonstrated that the CdSeS/TiO2 heterostructure exhibits the highest performances as photoelectrode [39] More recently, small CdSe NRs [40] or type II CdSe/CdSexTe1 x NRs [41] were also used as light harvesters to develop TiO2 based solar cells. Core/shell TiO2/CdSe NRs were also prepared by growing CdSe quantum dots onto TiO2 NRs at high temperature [42] In this paper, we report an investigation on the synthesis of CdSe NR sensitized TiO2 nanoparticles and on the use of these materials for the degradation of rhodamine B (RhB) in aqueous solution. Our results demonstrate that the composite containing 2 wt CdSe NRs exhibits the optimal photocatalytic activity under solar or visible light irradiation. Moreover, the photocatalytic response was maintained after ten cycles in simulated sunlight. A possible mechanism is also discussed. Experimental Chemicals Cadmium acetate (Cd(OAc) 99.995% Sigma) sodium selenite (Na2SeO3, 99% Sigma) diethylenetriamine (99% Sigma) TiO2 nanoparticles (Sigma Aldrich, Aeroxide(r) P25, CAS: 13463 67 7) rhodamine B (RhB, >95% Sigma) tert butanol (t BuOH, >99.5% Sigma) p benzoquinone >98% Sigma) and ethanol >99% anhydrous) were used as received without additional purification. All solutions were prepared using Milli Q water (18.2 MO*cm, Millipore) as the solvent. Synthesis of CdSe nanorods CdSe NRs were synthetized via a solvothermal method according to the protocol described by Li et al. [43] with slight modifications. Briefly, diethylenetriamine (34.3 mL) and water (5.8 mL) were mixed in a reaction flask and the mixture stirred for 5 min. Next, Cd(OAc)2 (0.266 g, 1 mmol) and Na2SeO3 (0.173 g, 1 mmol) were added and the mixture further stirred for 30 min at room temperature to ensure complete dissolution of precursors. Next, the solution was transferred to a teflonlined stainless steel autoclave with 100 mL capacity and heated to 180 degC for 12 h. After cooling to room temperature, the CdSe NRs were recovered by centrifugation (4000 rpm for 15 min) washed with water (5 x 10 mL) then with ethanol (2 x 10 mL) and finally dried at 50 degC for 12 h. Preparation of CdSe/TiO2 composites CdSe/TiO2 composites with a varied content of CdSe NRs (0.5, 1, 2 and 5 wt were prepared. For the CdSe (2 wt /TiO2 composite, commercial Aeroxide(r) P25 TiO2 nanoparticles (250 mg) and CdSe NRs (5 mg) were dispersed by sonication in 5 mL water for 30 min. Next, the mixture was heated to 70 degC to evaporate water. The solid obtained was washed with water (3 x 10 mL) with ethanol (3 x 5 mL) and then calcined under air at 300 degC for 1 h to couple the CdSe NRs with TiO2. CdSe/TiO2 composites with different wt CdSe NRs were prepared using a similar synthetic procedure. Beilstein J. Nanotechnol. 2017, 8, 2741 2752. 2743 Photocatalytic activity measurements The photocatalytic activity of CdSe/TiO2 composites was evaluated by the degradation of RhB in aqueous solution. Sylvania LuxLine FHO T5 neon tubes were used as the simulated solar light source (light intensity 5 mW/cm2) A polycarbonate filter was added for experiments conducted under visible light irradiation (light intensity 10 mW/cm2) In a typical experiment, 50 mg of the CdSe/TiO2 composite were dispersed in 50 mL of aqueous solution of RhB (10 mg/L) in a 70 mL glass flask and the mixture was magnetically stirred in the dark under ambient conditions for 45 min to reach a thorough adsorption desorption equilibrium. After that period, the light was turned on. Aliquots of 2 mL were taken at regular time intervals and centrifuged (4000 rpm for 2 min) to remove the CdSe/TiO2 photocatalyst. The relative concentration of RhB in the solution was determined by comparing its UV visible absorption at 554 nm with that of the starting solution. The mechanism of RhB photodegradation in aqueous solution was investigated through the use of scavengers. t BuOH and p benzoquinone, used as hydroxyl and superoxide scavengers, were used at concentrations of 1 and 10 mM, respectively. Characterization Transmission electron microscopy (TEM) investigations were performed with a JEOL ARM 200F Cold FEG TEM/STEM (point resolution 0.19 nm in TEM mode and 0.078 nm in STEM mode) fitted with a GIF Quatum ER. For each sample, one drop of a dispersed solution was deposited on holey carbon grids and imaged. Scanning electron microscopy (SEM) images were prepared using a JEOL SEM JSM 6490 LV. The crystalline phase of the powders was determined by powder X ray diffraction (XRD) on an X'Pert MPD diffractometer (Panalytical AXS) with a goniometer radius of 240 mm, fixed divergence slit module (1/2deg divergence slit, 0.04 rd Sollers slits) and an X'Celerator as a detector. The samples were placed on a silicon zero background sample holder and the XRD patterns were recorded at room temperature using Cu Ka radiation (l 0.15418 nm) XPS analysis was conducted on a Gammadata Scienta (Uppsala, Sweden) SES 200 2 spectrometer under ultra high vacuum conditions (P 10 9 mbar) For all peak fitting procedures the CASA XPS software (Casa Software Ltd, Teignmouth, UK, http:/www.casaxps.com) was used and the areas of each component were modified according to classical Scofield sensitivity factors. All the optical measurements were performed at room temperature (20 1 degC) under ambient conditions. The absorption spectra of liquid samples were recorded on a Thermo Scientific Evolution 220 UV visible spectrophotometer. Diffuse reflectance spectra (DRS) were recorded on a Shimadzu 2600 UV visible spectrophotometer. BaSO4 powder was used as a standard for baseline measurements and spectra were recorded in a range of 250 1400 nm.", "author_names": [ "Fakher Laatar", "Hatem Moussa", "Halima Alem", "Lavinia Balan", "Emilien Girot", "Ghouti Medjahdi", "Hatem Ezzaouia", "Raphael Schneider" ], "corpus_id": 38694510, "doc_id": "38694510", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "CdSe nanorod TiO 2 nanoparticle heterojunctions with enhanced solar and visible light photocatalytic activity", "venue": "", "year": 2017 }, { "abstract": "A transformative approach is required to meet the demand of economically viable solar cell technology. By making use of recent advances in semiconductor nanocrystal research, we have now developed a one coat solar paint for designing quantum dot solar cells. A binder free paste consisting of CdS, CdSe, and TiO(2) semiconductor nanoparticles was prepared and applied to conducting glass surface and annealed at 473 K. The photoconversion behavior of these semiconductor film electrodes was evaluated in a photoelectrochemical cell consisting of graphene Cu(2)S counter electrode and sulfide/polysulfide redox couple. Open circuit voltage as high as 600 mV and short circuit current of 3.1 mA/cm(2) were obtained with CdS/TiO(2) CdSe/TiO(2) electrodes. A power conversion efficiency exceeding 1% has been obtained for solar cells constructed using the simple conventional paint brush approach under ambient conditions. Whereas further improvements are necessary to develop strategies for large area, all solid state devices, this initial effort to prepare solar paint offers the advantages of simple design and economically viable next generation solar cells.", "author_names": [ "Matthew Genovese", "Ian Lightcap", "Prashant V Kamat" ], "corpus_id": 8859259, "doc_id": "8859259", "n_citations": 90, "n_key_citations": 1, "score": 0, "title": "Sun believable solar paint. A transformative one step approach for designing nanocrystalline solar cells.", "venue": "ACS nano", "year": 2012 } ]

[ { "abstract": "", "author_names": [ "Ding Li", "Liefeng Feng", "Wei Yang", "Xiufang Yang", "Xiaodong Hu", "Cunda Wang" ], "corpus_id": 212995778, "doc_id": "212995778", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Redefinition the quasi Fermi energy levels separation of electrons and holes inside and outside quantum wells of GaN based multi quantum well semiconductor laser diodes", "venue": "", "year": 2020 }, { "abstract": "", "author_names": [ "Dorin Dadarlat", "Rodica M Candea", "M Barlea" ], "corpus_id": 119822438, "doc_id": "119822438", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Majority carrier concentration and quasi Fermi level for Pb1 xSnxTe DH diode lasers", "venue": "", "year": 1983 }, { "abstract": "We show that the bifurcations between dynamical states originating in the nonlinear dynamics of an external cavity semiconductor laser at constant current can be detected by its terminal voltage V. We experimentally vary the intensity fed back into the gain medium by the external cavity and show that the dc component V(dc) of V tracks the optical intensity based bifurcation diagram. It is shown using computational results based upon the Lang Kobayashi model that whereas optical intensity accesses the dynamical state variable |E| V is related to population inversion carrier density N. The change in feedback strength affects N and thereby the quasi Fermi energy level difference at the p i n junction band gap of the gain medium. The change in the quasi Fermi energy level thereby changes the terminal voltage V. Thus V is shown to provide information on the change in the dynamical state variable N, which complements the more conventionally probed optical intensity.", "author_names": [ "Aakash A Sahai", "B Y Kim", "Daeyoung Choi", "Alexandre Locquet", "David S Citrin" ], "corpus_id": 44452990, "doc_id": "44452990", "n_citations": 12, "n_key_citations": 0, "score": 1, "title": "Mapping the nonlinear dynamics of a laser diode via its terminal voltage.", "venue": "Optics letters", "year": 2014 }, { "abstract": "Analysis of spontaneous emission spectra of GaInP quantum well laser diodes above and below threshold show that the quasi Fermi level separation pins within the quantum wells but not throughout the whole device structure. By reproducing the temperature and cavity length dependence of the external differential efficiency using these measurements it is shown that a value of internal differential efficiency which is nonunity is due to current spreading and incomplete carrier injection and that the temperature dependence is due to the temperature dependence of the efficiency with which carriers are injected into the quantum well.", "author_names": [ "Peter M Smowton", "Peter Blood" ], "corpus_id": 39995089, "doc_id": "39995089", "n_citations": 16, "n_key_citations": 3, "score": 1, "title": "Fermi level pinning and differential efficiency in GaInP quantum well laser diodes", "venue": "", "year": 1997 }, { "abstract": "Signal monitoring characteristics of terminal voltage change across laser diode optical switches (LDSW) have been studied. The terminal voltage changes are caused by the photovoltaic effect in the OFF state and by the quasi Fermi level change in the ON state. The baseband frequency response characteristics are analyzed by small signal analysis and coincide well with the measured characteristics. The 6 dB down frequency response bandwidths are verified to be very wide in both the ON and OFF states.", "author_names": [ "Masahiro Ikeda" ], "corpus_id": 110959755, "doc_id": "110959755", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Signal monitoring characteristics for laser diode optical switches", "venue": "", "year": 1985 }, { "abstract": "Signal monitoring characteristics of terminal voltage change across laser diode optical switches (LDSW) have been studied. The terminal voltage changes are caused by the photovoltaic effect in the OFF state and by the quasi Fermi level change in the ON state. The baseband frequency response characteristics are analyzed by small sig nal analysis and coincide well with the measured characteristics, The 6 dB down frequency response bandwidths are verified to be very wide in both the ON and OFF states.", "author_names": [ "Nippon Telegraph" ], "corpus_id": 110516636, "doc_id": "110516636", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Signal Monitoring Characteristics for Laser Diode Optical Switches", "venue": "", "year": 1985 }, { "abstract": "Abstract Two dimensional semiconductors have emerged as promising candidates for next generation optoelectronics due to their excellent carrier transport and strong light matter interaction. Meanwhile, the feasibility of arbitrary van der Waals integration enables the construction of devices with designable interface properties. In this work, WSe2/WS2 heterostructures with type II band alignment were fabricated for high performance self powered photodetector and photovoltaics. Due to the ambipolar nature of WSe2, the junction property could be efficiently modulated with electrostatic doping. Under optimized gate voltage and 532 nm laser illumination, the heterojunction yields a high open circuit voltage of 0.58 V, the power conversion efficiency of 2.4% and external quantum efficiency of 50.2% The modulation of the photovoltaic response is demonstrated to be a combined effect of quasi Fermi level tuning at the interface and channel conductivity change. Moreover, the diode exhibits spectral photoresponse from visible to the near infrared region when it functions as a self powered photodetector. The photoresponsivity reaches 216 mA/W and the rise and fall time are 80 ms and 90 ms, respectively. This work not only advances our fundamental understanding of device physics in van der Waals solar cells but also uncovers the great potential applications of WSe2/WS2 heterojunction in solar energy conversion and photodetectors.", "author_names": [ "Pei Lin", "Jinke Yang" ], "corpus_id": 219918894, "doc_id": "219918894", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Tunable WSe2/WS2 van der Waals heterojunction for self powered photodetector and photovoltaics", "venue": "Journal of Alloys and Compounds", "year": 2020 }, { "abstract": "Owing to the dependence of the difference of quasi Fermi levels on the carrier densities inside the diode, it is anticipated that, accompanying the appearance of an optical hysteresis loop on the P v (output power oscillation frequency) curve of a tunable external cavity semiconductor laser, a hysteresis loop of the voltage across (or current passing) the diode should be expected.", "author_names": [ "Yan Deng", "Jianguo Chen", "Dayi Li" ], "corpus_id": 232659082, "doc_id": "232659082", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Bistability of current passing diode of a tunable external cavity semiconductor laser", "venue": "", "year": 2002 }, { "abstract": "We present an efficient 3D simulation method for a nitride based visible light laser diode. The method involves the separation of the overall device simulation into coupled simplified models for the quantum wells, thep n junction, the bulk regions, and the thermal environment, each solved on a different mesh. I. SIMULATION PROCEDURE Drift diffusion simulation of complex 3D laser structures is a timeand resource intensive computational task. In order to accomplish a relatively fast 3D simulation of the laser diode, the laser simulation problem is separated into a set of subproblems, each of which can be solved on a different spatial domain [1] [2] The coupling between these sub problems is generally weak and can be restricted to a subset of the points on the larger domain. The sub problems are as follows, in order of increasing domain size: quantum well density of states, stimulated and spontaneous recombination in the k p approximation [3] p n junction recombination and optical gain in the quasiequilibrium approximation; bulk region carrier transport in the unipolar drift current approximation; optical mode calculation and a photon rate equation; thermal transport simulation using the continuity equation for heat flux. Each of these sub problems is described in more detail below. The quantum well density of states and recombination rates are calculated using a 6 band k *p solver including strain. The self consistent electric potential (including the bending due to piezoelectric and spontaneous polarization fields) is passed to thek *p solver from the quasi equilibriump n junction solver described in the next paragraph. The Hamiltonian is discretized using the real space finite difference procedure, and solved to obtain the eigenstates in the well. The bound state energies and wavefunctions are used in conjunction with the electron and hole quasi Fermi levels passed from the p n junction solver to calculate the dark recombination, spontaneous recombination, and optical gain of the quantum well. The p n junction is simulated using a set of parallel 1D models in the quasi equilibrium approximation. Each 1D model represents a patch of the p n junction, as shown in Fig. 1. The recombination and gain of a p n junction patch are calculated as follows. Starting from equilibrium, the strain and polarization of thep n junction region are calculated, and the nonlinear 1D Poisson equation with self consistent electron and hole concentrations is solved in the growth direction using the finite element discretization procedure [4] Although the p n junction requires fine spatial meshing, the use of 1D models greatly reduces the problem size, while neglecting current spreading in the active layer. The bias applied to the patch is increased in steps, and the electron and hole quasiFermi levels are assumed to be spatially invariant and equal to then side andp side Fermi levels, respectively. The nonlinear Poisson equation is solved again for each bias step. The dark recombination, spontaneous recombination, and optical gain of the active layer patch are calculated and stored in a look up table for a range of applied bias conditions and temperatures. This data is later used as described in the next paragraph. The carrier transport in the bulk regions of the device bounding the active region are modeled in 3D, in order to obtain current spreading and series resistance in complex laser diode structures. The drift continuity equation is solved for the majority carrier population using the finite element discretization procedure. At the boundaries of the p n junction region, the current through each p n junction patch is obtained from the recombination rates and optical gain from the lookup table described above, along with the photon number from the photon rate equation: j e(R R gNG) (1) whereR are the dark/radiative spontaneous recombination rates,N is the number of photons in the resonator, G andg are the modal gain and the overlap factor, respectively. The optical mode calculation, necessary to calculate modal overlap factors and the photon lifetime of the lasing mode, can be carried out using a variety of approaches, e.g. [5] The photon rate equation is given by many authors, e.g. [6] The thermal transport simulation is modeled using a thermal continuity equation [7] Heat generation due to Joule heating is calculated in the bulk regions, while the heat generation in the p n junction region is calculated from energy balance considerations: the total power dissipated in the p n junction region minus the power loss due to optical recombination. The thermal continuity equation is discretized using finite elements, and the mesh is a superset of the mesh used for bulk carrier transport. Self consistency between all the layers of models is achieved by iteration. The active layer and bulk transport are solved simultaneously using the Newton method [8] while the NUSOD 2009 Postdeadline Paper", "author_names": [ "Michael Povolotskyi", "B J Connors", "Benjamin Klein" ], "corpus_id": 221704855, "doc_id": "221704855", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Efficient multiscale simulation of InGaN laser diodes", "venue": "", "year": 2018 }, { "abstract": "We identify that the stimulated emission of GaN laser diodes (LDs) emerges far below the traditionally recognized threshold from both optical and electrical experiments. Below the threshold, the linear polarized stimulated emission has been the dominating part of overall emission and closely related to resonant cavity. Its intensity increases super linearly with current while that of spontaneous emission increases almost linearly. Moreover, the separation of quasi Fermi levels of electrons and holes across the active region has already exceeded the photon emission energy, namely, realized the population inversion.", "author_names": [ "Ding Li", "Hua Zong", "Wei Yang", "Liefeng Feng", "Juan He", "Weimin Du", "Cunda Wang", "Ya-Hong Xie", "Zhijian Yang", "Bo Shen", "Guoyi Zhang", "Xiaodong Hu" ], "corpus_id": 34607198, "doc_id": "34607198", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Stimulated emission in GaN based laser diodes far below the threshold region.", "venue": "Optics express", "year": 2014 } ]

[ { "abstract": "The photocatalytic splitting of water into hydrogen and oxygen using solar energy is a potentially clean and renewable source for hydrogen fuel. The first photocatalysts suitable for water splitting, or for activating hydrogen production from carbohydrate compounds made by plants from water and carbon dioxide, were developed several decades ago. But these catalysts operate with ultraviolet light, which accounts for only 4% of the incoming solar energy and thus renders the overall process impractical. For this reason, considerable efforts have been invested in developing photocatalysts capable of using the less energetic but more abundant visible light, which accounts for about 43% of the incoming solar energy. However, systems that are sufficiently stable and efficient for practical use have not yet been realized. Here we show that doping of indium tantalum oxide with nickel yields a series of photocatalysts, In1 xNixTaO4 (x 0 0.2) which induces direct splitting of water into stoichiometric amounts of oxygen and hydrogen under visible light irradiation with a quantum yield of about 0.66% Our findings suggest that the use of solar energy for photocatalytic water splitting might provide a viable source for 'clean' hydrogen fuel, once the catalytic efficiency of the semiconductor system has been improved by increasing its surface area and suitable modifications of the surface sites.", "author_names": [ "Zhi-gang Zou", "Jinhua Ye", "Kazuhiro Sayama", "Hironori Arakawa" ], "corpus_id": 4357182, "doc_id": "4357182", "n_citations": 2442, "n_key_citations": 3, "score": 1, "title": "Direct splitting of water under visible light irradiation with an oxide semiconductor photocatalyst", "venue": "Nature", "year": 2001 }, { "abstract": "The photocatalytic splitting of water into hydrogen and oxygen using solar energy is a potentially clean and renewable source for hydrogen fuel. The first photocatalysts suitable for water splitting, or for activating hydrogen production from carbohydrate compounds made by plants from water and carbon dioxide, were developed several decades ago. But these catalysts operate with ultraviolet light, which accounts for only 4% of the incoming solar energy and thus renders the overall process impractical. For this reason, considerable efforts have been invested in developing photocatalysts capable of using the less energetic but more abundant visible light, which accounts for about 43% of the incoming solar energy. However, systems that are sufficiently stable and efficient for practical use have not yet been realized. Here we show that doping of indium tantalum oxide with nickel yields a series of photocatalysts, In(1 x)Ni(x)TaO(4) (x 0 0.2) which induces direct splitting of water into stoichiometric amounts of oxygen and hydrogen under visible light irradiation with a quantum yield of about 0.66% Our findings suggest that the use of solar energy for photocatalytic water splitting might provide a viable source for 'clean' hydrogen fuel, once the catalytic efficiency of the semiconductor system has been improved by increasing its surface area and suitable modifications of the surface sites.", "author_names": [ "Zhi-gang Zou", "Jinhua Ye", "Kazuhiro Sayama", "Hironori Arakawa" ], "corpus_id": 197160051, "doc_id": "197160051", "n_citations": 174, "n_key_citations": 4, "score": 0, "title": "Direct Splitting of Water under Visible Light Irradiation with an Oxide Semiconductor Photocatalyst.", "venue": "", "year": 2002 }, { "abstract": "The photocatalytic splitting of water into hydrogen and oxygen using solar energy is one of the most attractive renewable sources of hydrogen fuel. Therefore, considerable efforts have been paid in developing photocatalysts capable of using visible light, which accounts for about 43% of the solar energy. However such a photocatalyst has not been developed so far. We have developed a new Ni doped indium tantalum oxide photocatalyst, In1 x Nix TaO4 (x 0.0~0.2) which induced direct splitting of water into stoichiometric amount of oxygen and hydrogen under visible light irradiation with a quantum yield of about 0.66% at 420.7 nm. We have also developed a new two step water splitting system using two different semiconductor photocatalysts, Pt/WO3 photocatalyst for oxygen evolution and Pt/SrTiO3 (Cr Ta doped) photocatalyst for hydrogen evolution, and a redox mediator, I /IO3 mimicking the Z scheme mechanism of the natural photosynthesis. The quantum yield of this system was about 0.1% at 420.7nm. Both photocatalytic methods are the first examples for visible light water splitting system in the world.Copyright (c) 2003 by ASME", "author_names": [ "Hironori Arakawa", "Zhi-gang Zou", "Kazuhiro Sayama", "Ryu Abe" ], "corpus_id": 98127141, "doc_id": "98127141", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Solar Hydrogen Production: Direct Water Splitting Into Hydrogen and Oxygen by New Photocatalysts Under Visible Light Irradiation", "venue": "", "year": 2003 }, { "abstract": "Abstract The research on a new series of solid photocatalysts with different crystal structures was reviewed. The first system is A2B2O7 pyrochlore crystal type: Bi2MNbO7 (M=Al, Ga, In and Y, rare earth, and Fe) which is cubic system and space group Fd3m. The second system is ABO4 stibotantalite crystal type: BiMO4 (M=Nb5+ Ta5+ in which both the triclinic system with space group P1 in the case of M=Ta and the orthorhombic system with space group Pnna in the case of M=Nb. The third system is ABO4 wolframite crystal type: InMO4 (M=Nb5+ Ta5+ which is monoclinic system and space group P2/a. Although these photocatalysts crystallize in the different crystal structure, they contain the same octahedral TaO6 and/or NbO6 in the different photocatalysts. The band structure of the photocatalysts is defined by Ta/Nb d level for a conduction band and O 2p level for a valence band. The band gaps of the photocatalysts were estimated to be between 2.7 and 2.4 eV. Metal doped InTaO4 photocatalysts were also investigated. Under visible light (l>420 nm) or ultra violet irradiation, the H2 and/or O2 evolutions were observed from pure water as well as aqueous CH3OH/H2O and AgNO3 solutions. The photocatalytic activity increases significantly by loading co catalysts such as Pt, RuO2 and NiOx on the surface of the photocatalysts. Finally, direct water splitting into H2 and O2 under visible light irradiation was firstly established using newly synthesized NiOx (partly oxidized nickel) promoted In0.9Ni0.1TaO4 photocatalyst.", "author_names": [ "Zhi-gang Zou", "Hironori Arakawa" ], "corpus_id": 95404805, "doc_id": "95404805", "n_citations": 219, "n_key_citations": 1, "score": 0, "title": "Direct water splitting into H2 and O2 under visible light irradiation with a new series of mixed oxide semiconductor photocatalysts", "venue": "", "year": 2003 }, { "abstract": "Abstract Green and efficient energy technologies are a key point where nanoscience could make a difference in the paradigm shift from fossil fuels to renewable sources. One attractive possibility is the utilization of solar energy to obtain electricity or chemical fuel based on the ability of semiconductor nanomaterials to function as photocatalysts promoting various oxidation and reduction reactions under sunlight. We report on a novel class of Bi based photocatalysts for hydrogen production via water splitting. A screening DFT investigation was performed on the Bi2(MO4)3 (M Cr, Mo, and W) systems. The Bi2(CrO4)3 system exhibits the smallest band gap energy, the highest dielectric constant, and the highest absorption in visible region among the other counterpart materials. Consequently, Bi2(CrO4)3 nanoparticles were synthesized via a simple one pot method at room temperature and characterized by XRD, XPS, DRS, FE SEM, HR TEM, and Raman spectroscopy. The as prepared yellow Bi2(CrO4)3 nanoparticles exhibited a direct band gap energy of 2.45 eV. The photoactivity of the as prepared Bi2(CrO4)3 nanoparticles was tested toward the photocatalytic hydrogen production, where reasonable rates of 522.44, 174.15, and 88.24 mmol/g/h were achieved under UV, AM 1.5, and visible irradiations, respectively in the absence of any hole scavengers. Those rates are higher than those reported for Bi based photocatalysts.", "author_names": [ "Mahmoud Hamza", "Ayat N El-Shazly", "Sarah A Tolba", "Nageh K Allam" ], "corpus_id": 209710842, "doc_id": "209710842", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Novel Bi based photocatalysts with unprecedented visible light driven hydrogen production rate: Experimental and DFT insights", "venue": "", "year": 2020 }, { "abstract": "Developing new technology to utilize solar power as alternative energy is imperative to meet the challenge of fossil fuel consumption and consequently environmental contamination. Photocatalytic overall water splitting is regarded as an ideal reaction for realizing solar to chemical energy conversion. Up to date, many particle suspension systems have been studied on a laboratory scale with inorganic semiconductors including metal oxides, (oxy)nitrides, and oxysulfides under ultra violet (UV) light irradiation [1] However, the solar to hydrogen energy conversion efficiency (STH) offered by these efforts is far from the requirements of scale up industrialization since visible light photons are not efficiently used. When Wang et al. [2] firstly reported g C3N4 for water splitting in 2009, conjugated polymers were merging as a promising candidate due to their easily tunable electronic properties over the inorganic counterparts for better visible light response [3] Realizing overall water splitting using g C3N4 based materials is attractive but proved to be challenging. As a single component photocatalyst, constructing spatially separated oxidation and reduction centers has been demonstrated to achieve the overall water splitting [4] Besides, the incorporation of carbon dots (C dots) promoting the H2O2 decomposition, is also an effective way to reach the overall water splitting [5] Z scheme, mimicking the natural photosynthesis process, provides an effective route to enhance the charge separation by forming a heterojunction from two semiconductors. The matching energy diagram and the efficient charge transfer are critical factors for the photocatalytic system, which depends on the types of both semiconductors and their contact interface. Significant progress has been made by Shen's group [6] through constructing two dimensional/two dimensional (2D/2D) Z scheme heterostructures of the carbon nitride based polymers. In this work, ultrathin carbon nitride nanosheets (CNN) with different band structures by modulating the levels of boron dopants and nitrogen defects were prepared to act as H2and O2 evolving photocatalysts, respectively (Figure 1(a) Through electrostatic self assembly and p p stacking, the boron doped and nitrogen deficient carbon nitride 2D nanosheets (BDCNN) are effectively coupled together to achieve a g C3N4 based 2D/2D Zscheme heterostructure. It enables overall water splitting to be realized due to their ultrathin nanostructures, strong interfacial interaction, and staggered band alignment (Figure 1 (b d) With the help of Pt and Co(OH)2 cocatalysts, this gC3N4 based heterostructure achieved a STH of 1.16% standing at the highest level reported for polymer photocatalysts for overall water splitting (Figure 1(e) The superior performance is experimentally and theoretically evidenced to originate from the direct Z scheme charge transfer pathway with the band structures of both the H2and O2 evolving components well optimized, which endows this g C3N4 based heterostructure with excellent charge transfer efficiency for facilitating charge separation and enough driving forces for the water redox reactions to simultaneously produce O2 and H2. This work rationally combines", "author_names": [ "Xupeng Zong", "Wenshuai Jiang", "Zaicheng Sun" ], "corpus_id": 233016305, "doc_id": "233016305", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Efficient photocatalytic overall water splitting achieved with polymeric semiconductor based Z scheme heterostructures", "venue": "Science China Chemistry", "year": 2021 }, { "abstract": "Direct water splitting into H2 and O2 using photocatalysts by harnessing sunlight is very appealing to produce storable chemical fuels. Conjugated polymers, which have tunable molecular structures and optoelectronic properties, are promising alternatives to inorganic semiconductors for water splitting. Unfortunately, conjugated polymers that are able to efficiently split pure water under visible light (400 nm) via a four electron pathway have not been previously reported. This study demonstrates that 1,3 diyne linked conjugated microporous polymer nanosheets (CMPNs) prepared by oxidative coupling of terminal alkynes such as 1,3,5 tris (4 ethynylphenyl) benzene (TEPB) and 1,3,5 triethynylbenzene (TEB) can act as highly efficient photocatalysts for splitting pure water (pH 7) into stoichiometric amounts of H2 and O2 under visible light. The apparent quantum efficiencies at 420 nm are 10.3% and 7.6% for CMPNs synthesized from TEPB and TEB, respectively; the measured solar to hydrogen conversion efficiency using the full solar spectrum can reach 0.6% surpassing photosynthetic plants in converting solar energy to biomass (globally average 0.10% First principles calculations reveal that photocatalytic H2 and O2 evolution reactions are energetically feasible for CMPNs under visible light irradiation. The findings suggest that organic polymers hold great potential for stable and scalable solar fuel generation.", "author_names": [ "Li-xi Wang", "Yangyang Wan", "Yanjun Ding", "Sikai Wu", "Yongde Zhang", "Xinlei Zhang", "Guoqing Zhang", "Yujie Xiong", "Xiaojun Wu", "Jinlong Yang", "Hangxun Xu" ], "corpus_id": 205281311, "doc_id": "205281311", "n_citations": 171, "n_key_citations": 0, "score": 0, "title": "Conjugated Microporous Polymer Nanosheets for Overall Water Splitting Using Visible Light.", "venue": "Advanced materials", "year": 2017 }, { "abstract": "Photocatalytic water splitting using semiconductor materials has attracted considerable interest due to its potential for clean production of H2 from water through the conversion of abundant solar energy into chemical energy. This article briefly analyzed the trend and progress in the research and development of visible light responsive photocatalysts for water splitting in the past few years. Particularly, metal sulfides and composite photocatalysts were discussed. This brief review article aims at facilitating a search of stable and efficient photocatalysts for water splitting, and revealing fundamental insight into the development of novel visible light adsorbing photocatalysts. Keyword: water splitting, visible light, hydrogen production, metal sulfide Hydrogen (H2) production using visible light photocatalyst for water splitting has attracted considerable attention due to the growing demand for environmentally friendly and sustainable energy sources. The number of journal articles on water splitting for H2 production dramatically increased over the past few years (Fig.1) highlighting the tremendous interests in photocatalytic water splitting as a means of producing renewable clean energy production with minimum carbon footprint. Since the early 1970s, intensive efforts have been directed toward research and development of various photocatalytic materials for water splitting for H2 production. Most traditional photocatalysts, such as TiO2 and ZnGa2O4, have relatively large band gaps and thus can capture only ultraviolet (UV) irradiation, which accounts for a small fraction of solar irradiation. To overcome this limitation, many types of visible light absorbing materials with narrower band gaps, such as mixed oxides, oxynitride, and metal sulfides, are developed as shown in Fig. 2. Until today, developing visible light photocatalysts remains the focus in this field. As shown in Fig. 1, the number of journal articles on visible light driven photocatalyst between 2006 and 2010 is almost 5 times the number of journal articles published between 1981 and 1985. It is also worth noting that before 2000, the publications on water splitting under UV irradiation outnumbered those under visible light. By contrast, after 2000, much more attention is being directed toward water splitting under visible light, especially in the past five years. Moreover, the number of journal articles on UV driven water splitting has declined over that past 5 years. This article compared the quantum yield (QY) and H2 productivity in different novel visible light adsorbing photocatalytic systems that were developed in the past few years. This article also examined the colloidal stability or durability, quantum efficiency, and potential environmental impacts between different studies, which laid groundwork toward developing and designing new rationale Fig. 1. The number of journal articles on water splitting published with years. VIS: visible light. UV: ultraviolet. NSTI Nanotech 2013, www.nsti.org, ISBN 978 1 4822 0586 2 Vol. 3, 2013 584 visible light responsive photocatalysts. 1. Visible light driven metal sulfide photocatalyst for water splitting Metal sulfides are attractive materials as candidates of visible light driven photocatalysts due to the narrow band gaps and negative valence band potentials. Despite the excellent visible light photocatalytic activity, they often exhibit poor photostability and undergo photocorrosion with prolonged light illumination. Yet the photocorrosion can be suppressed in the presence of sacrificial reagents. Many metal sulfide photocatalysts have been successful for H2 evolution in the presence of sacrificial reagents as demonstrated in Table 1. For instance, CdS is one of the most popular photocatalysts, 4 because of its appropriate band gap (2.4eV) and electronic structures (e.g. the conduction band is 0.9 eV in reference to NHE at PH=7, the valence band is +1.5 eV in reference to NHE at PH=7) Different photocatalysts led to dramatically different QYs for different systems (Table 1) In addition, it is actually challenging to quantitatively compare the H2 production efficiency and productivity due to the lack of a common measure or indicator. So, H2 productivity expressed with different units (i.e. mmol/h, mmol/mg/h, and mmol/m/h) were proposed and calculated in Table 1. Due to the availability of data or experimental details in the reference articles, we were able to obtain some of the H2 productivity quantities, which appeared to vary significantly with photocatalytic systems. Yan et al. reported that a quantum yield of 93% at 420 nm using the Pt PdS/CdS photocatalyst in the presence of the sacrificial reagent of Na2S and Na2SO3 which is the highest photocatalytic activity so far. Accordingly, its H2 productivity seems to be the highest. However, Graphene CdS and CdSeZnS/Zr/Ti/phosphate, if evaluated by the H2 production rate per unit photocatalyst mass, would apparently yield much greater H2 than Pt PdS/CdS. Thus, it is important develop holistic evaluation methods to access the H2 productivity for different photocatalytic systems. 2. Water splitting for H2 production using composite photocatalysts Clearly, efficient photocatalytic water splitting systems require stable photocatalysts that have photocatalytic activity with repeated consecutive use. Most recently, many efforts have focused on the design of novel semiconductor materials and the optimization of chemical composition and microstructures to increase the photostability and quantum yield. For example, multicomponent sulfides, such as ZnIn2S4, 6 and (CuAg)xIn2xZn2(1 2x)S2 7, 8 have been studied as a new class of visible light driven photocatalysts for water splitting and H2 production. Zhang et al. recently developed a visible light responsive photocatalyst (Ru/(CuAg)0.15In0.3Zn1.4S2) and successfully achieved H2 evolution in the presence of KI as the sacrificial reagent. The study also examined the kinetics of photocatalytic generation of H2, stability and reusability of the catalyst over multiple cycles of H2 production and catalyst regeneration, which is not commonly reported elsewhere. The examination of stability and longevity of photocatalytic H2 production is important and necessary to quantitatively compare the actual H2 productivity from different photocatalytic systems. The photocatalyst reported by Zhang et al was well crystallized particles (30 50 nm in diameter) with high photocatalytic activity and broad visible light absorbance (from 400 nm up to 650 nm) The highest H2 production rate was approximately 190 6.5 mmol*h at the initial pH of 4 Fig. 2. The number of journal articles on different popular visible light responsive photocatalysts published from 2007 to 2012. NSTI Nanotech 2013, www.nsti.org, ISBN 978 1 4822 0586 2 Vol. 3, 2013 585 and 0.2 M KI as electron donor. The highest QY (QY under the wavelength of 420+ 5 nm) was 4.6 0.3% Although this QY does not seem to be stunning and even lower than those of some similar catalysts, such as Pt/CdS (QY 24% and (CuAg)0.15In0.3Zn1.4S2 (QY 7% the catalyst exhibited relatively good colloidal stability and was able to capture a wide spectrum of the solar irradiation (400 650 nm) Most importantly, this article provided systematic investigations on the longevity of the photocatalyst with consecutive reaction cycles. The study monitored the particle size distribution and metal ion release during the photocatalytic H2 production, which help understand why the H2 production rate decreased from 190 to 120 mmol*h with over different reaction cycles. It was experimentally observed that the photocatalyst particles underwent pronounced aggregation, which led to the increase in particle size; and a significant release of metal ions was observed during H2 production, which led to a loss of the catalyst mass and potential changes in the photocatalytic activity. Consequently, these processes may result in the decrease of photocatalytic activity and stability. 3. Conclusion Solar water splitting for H2 production is important to obtain clean energy in the future. Nowadays, there are many photocatalysts have been developed, and the focus is largely on the novel material synthesis and improvement of photocatalytic activity. In the future, it is necessary to take the stability and reusability of photocatalysts into consideration. In addition, applications of photocatalyst materials made of earth abundant elements would be more attractive and critical for energy sustainability. Table 1. Comparison of hydrogen evolution with different visible light responsive photocatalysts Catalyst Light source QY H2 Productivity Ref. mmol/h mmol/mg/h mmol/m/h Pt/CdS/TiO2 N.A. 20 54 0.68 N.A. 1 Pt PdS/CdS =420 nm 93 8770 29.23 N.A. 2 Pt/[In(OH)ySz]:Zn =420 nm 0.59 67 0.22 N.A. 12 PPy/CdS =430 nm N.A. 110 0.73 N.A. 13 Graphene CdS 420 nm 22.5 1120 556 N.A. 14 CdSeZnS/Zr/Ti/phosphate 420 nm 9.6 714 35.71 N.A. 15 CdS/TiO2 420 nm 43.4 402 N.A. N.A. 16 (Cd0.8Zn0.2)S =420 nm N.A. 302 3.02 N.A. 17", "author_names": [ "Yongsheng Chen", "John C Crittenden", "J Huang", "Daisuke Minakata", "Peng Wang", "Guangshan Zhang", "Wen Zhang" ], "corpus_id": 155789965, "doc_id": "155789965", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Water Splitting for H2 Production using Visible light responsive Photocatalysts", "venue": "", "year": 2013 }, { "abstract": "57 Water splitting using a photocatalyst for direct solar hydrogen production from sunlight and water, has been regarded as an important approach to artificial photosynthesis.1,2 Solar hydrogen, which is the simplest solar fuel, can then be converted to various energy carriers such as organic hydrides, methanol, methane, and ammonia for transportation and storage. Thus, energy systems based on solar hydrogen can lead to a stable, secure, and ecologically friendly society. Although solar fuel production using electricity from photovoltaic cells and concentrated solar thermal power is an existing technology, direct synthesis of solar fuels by artificial photosynthesis has more scalability in terms of system cost. To split water into hydrogen and oxygen, 1.23 V of energy is required, corresponding to a 2 electron reaction. An energy of 1.23 V is equivalent to a photon energy of 1000 nm, so that the visible light (400 800 nm in wavelength) that represents half of the solar energy spectrum can be thermodynamically used for water splitting. The challenge is to obtain an efficient photocatalyst that has an absorption edge in longer wavelength and the ability to split water. Highly efficient oxide photocatalysts, such as La doped NaTaO3, and Zn doped Ga2O3, have been reported with quantum efficiencies of over 50%.3 5 However, these oxides only absorb ultraviolet (UV) light with wavelengths shorter than 300 nm. In the solar spectrum at the earth's surface, such short UV light is not present, so that these oxides cannot operate efficiently under solar irradiation. Most oxides have band gaps wider than the UV energy because of the deeper O 2p potential of the valence band. The valence band of nitrides is composed of the shallower N 2p potential, and thus their band gaps are generally narrower than those of oxides. For photocatalytic water splitting, photoexcited electrons in the conduction band reduce water to evolve hydrogen, and photogenerated holes in the valence band oxidize water to evolve oxygen. Therefore, the potential of the conduction band should be shallower than the reversible hydrogen potential and the potential of the valence band should be deeper than the reversible oxygen potential. In this article, the properties of oxynitride and nitride photocatalysts for water splitting are described. Surface modification of semiconductor photocatalyst particles with hydrogenor oxygen evolving cocatalysts is an indispensable technique in the study of photocatalytic water splitting. In fact, hydrogen evolution cocatalysts are required Photocatalytic Water Splitting Using Oxynitride and Nitride Semiconductor Powders for Production of Solar Hydrogen", "author_names": [ "Jun Kubota", "Kazunari Domen" ], "corpus_id": 99984476, "doc_id": "99984476", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "Photocatalytic Water Splitting Using Oxynitride and Nitride Semiconductor Powders for Production of Solar Hydrogen", "venue": "", "year": 2013 }, { "abstract": "The design, synthesis, and photoelectrochemical characterization of Co3 (PO4 )2 a hydrogen evolving catalyst modified with reduced graphene oxide (RGO) is reported. The 3 D flowerlike Co3 (PO4 )2 heterojunction system, consisting of 3 D flowerlike Co3 (PO4 )2 and RGO sheets, was synthesized by a one pot in situ photoassisted method under visible light irradiation, which was achieved without the addition of surfactant or a structure directing reagent. For the first time, Co3 (PO4 )2 is demonstrated to act as a hydrogen evolving catalyst rather than being used as an oxygen evolving photoanode. In particular, 3 D flowerlike Co3 (PO4 )2 anchored to RGO nanosheets is shown to possess dramatically improved photocatalytic activity. This enhanced photoactivity is mainly due to the staggered type II heterojunction system, in which photoinduced electrons from 3 D flowerlike Co3 (PO4 )2 transfer to the RGO sheets and result in decreased charge recombination, as evidenced by photoluminescence spectroscopy. The band gap of Co3 (PO4 )2 was calculated to be 2.35 eV by the Kubelka Munk method. Again, the Co3 (PO4 )2 semiconductor displays n type behavior, as observed from Mott Schottky measurements. These RGO Co3 (PO4 )2 conjugates are active in the visible range of solar light for water splitting and textile dye degradation, and can be used towards the development of greener and cheaper photocatalysts by exploiting solar light.", "author_names": [ "Alaka Samal", "Smrutirekha Swain", "Biswarup Satpati", "Dipti P Das", "Barada Kanta Mishra" ], "corpus_id": 43640360, "doc_id": "43640360", "n_citations": 31, "n_key_citations": 0, "score": 0, "title": "3 D Co3 (PO4 )2 Reduced Graphene Oxide Flowers for Photocatalytic Water Splitting: A Type II Staggered Heterojunction System.", "venue": "ChemSusChem", "year": 2016 } ]

[ { "abstract": "We introduce orthogonal fat trees as a type of interconnection network for parallel computers, and show how they can be used to maximize the number of processors in a massively parallel computer when the degree of the internal nodes and the diameter of the network are physically constrained. The basic building block of these orthogonal fat trees is a two level fat tree that is obtained from a complete set of mutually orthogonal Latin Squares. As a practical application of orthogonal fat trees, we propose a new interconnection network for a massively parallel computer based on the QROOOl Data Stream Controller Interface, an integrated circuit produced by National Semiconductor, which can sustain a throughput of up to 180 MBytes/sec. The network consists of multiple interconnected rings and is constrained to have at most 16 nodes per ring and a maximum diameter of four. Our solution yields a maximum of 51,984 processors.", "author_names": [ "Marcos Valerio", "Louise E Moser", "P M Melliar-Smith" ], "corpus_id": 18988439, "doc_id": "18988439", "n_citations": 26, "n_key_citations": 2, "score": 1, "title": "Recursively scalable fat trees as interconnection networks", "venue": "Proceeding of 13th IEEE Annual International Phoenix Conference on Computers and Communications", "year": 1994 }, { "abstract": "Orthogonal fat trees are a type of interconnection network with several desirable characteristics: short distance between processors, constant degree of the switching elements, uniform traffic load, symmetry, and recursive scalability. We first show how to build two level orthogonal fat trees, where each node has a fixed degree and there is a maximum distance of two between any two leaves. We then show how to provide fault tolerance by including redundant paths at the cost of reducing the number of leaves. Finally, we show how to construct large orthogonal fat trees from two level fat trees recursively.<ETX>", "author_names": [ "Marcos Valerio", "Louise E Moser", "P M Melliar-Smith" ], "corpus_id": 61681645, "doc_id": "61681645", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Fault tolerant orthogonal fat trees as interconnection networks", "venue": "Proceedings 1st International Conference on Algorithms and Architectures for Parallel Processing", "year": 1995 }, { "abstract": "We introduce and analyze a new family of multiprocesser interconnection networks, called generalized fat trees, which include as special cases the fat trees used for the connection machine architecture CM 5, pruned butterflies, and various other fat trees proposed in the literature. The generalized fat trees provide a formal unifying concept to design and analyse a fat tree based architecture. The extended generalized fat tree network XGFT(h; m/sub 1/ m/sub h/ w/sub 1/ w/sub h/ of height h has /spl Pi//sub i=1//sup h/ m/sub i/ leaf processors and the inner nodes serve only as switches or routers. Each non leaf node in level i has m/sub i/ children and each non root has w/sub i+1/ parent nodes. The generalized fat trees provide regularity, symmetry, recursive scalability, maximal fault tolerance, logarithmic diameter bisection scalability, and permit simple algorithms for fault tolerant self routing and broadcasting. These networks are also versatile, since they can efficiently embed rings, meshes and tori, trees, pyramids and hypercubes.<ETX>", "author_names": [ "Sabine R Ohring", "Maximilian Ibel", "Sajal K Das", "Mohan Kumar" ], "corpus_id": 26494144, "doc_id": "26494144", "n_citations": 155, "n_key_citations": 24, "score": 0, "title": "On generalized fat trees", "venue": "Proceedings of 9th International Parallel Processing Symposium", "year": 1995 }, { "abstract": "The BCDC network is a new server centric data center network based on crossed cube. Its decentralized and recursively defined features solve the bandwidth bottleneck problem of the upper switch in the tree structure and make it more scalable. In addition, the degree of BCDC server is constant, which reduces connection cost and technical difficulty relative to DCell and BCube. In this paper, we study and analyze the data communication, fault tolerance, and node disjoint paths of BCDC through practical experiments. The results show that BCDC is superior to DCell and Fat Tree in data communication. Moreover, in terms of fault tolerant routing and node disjoint paths, the performance of BCDC is no worse than that of DCell and FatTree. We also propose a one to one communication algorithm in BCDC under 1 restricted connectivity, analyze time complexity of algorithm, and give an upper bound of the conditional faulty diameter of BCDC under 1 restricted connectivity. The work in this paper provides an important basis for the design and application of the new data center network.", "author_names": [ "Shuangxiang Kan", "Jianxi Fan", "Baolei Cheng", "Xi Wang" ], "corpus_id": 220605130, "doc_id": "220605130", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The Communication Performance of BCDC Data Center Network", "venue": "2020 12th International Conference on Communication Software and Networks (ICCSN)", "year": 2020 }, { "abstract": "As the scale of supercomputers grows, so does the size of the interconnect network. Topology aware task mapping, which maps parallel application processes onto processors to reduce communication cost, becomes increasingly important. Previous works mainly focus on the task mapping between compute nodes (i.e. inter node mapping) while ignoring the mapping within a node (i.e. intra node mapping) In this paper, we propose a hierarchical task mapping strategy, which performs both inter node and intra node mapping. We consider supercomputers with popular fat tree and torus network topologies, and introduce two mapping algorithms: (1) a generic recursive tree mapping algorithm, which can handle both inter node mapping and intra node mapping; (2) a recursive bipartitioning mapping algorithm for torus topology, which efficiently partitions the compute nodes according to their coordinates. Moreover, a hierarchical task mapping library is developed. Experimental results show that the proposed approach significantly improves the communication performance by up to 77 with low runtime overhead.", "author_names": [ "Jingjin Wu", "Xuanxing Xiong", "Zhiling Lan" ], "corpus_id": 14771393, "doc_id": "14771393", "n_citations": 16, "n_key_citations": 1, "score": 0, "title": "Hierarchical task mapping for parallel applications on supercomputers", "venue": "The Journal of Supercomputing", "year": 2014 }, { "abstract": "The performance of the interconnect network is massively important in the modern day supercomputer and data centers. As a PhD student in the FSUCSEXPLORER (EXtreme scale comPuting,modeLing, netwORking systEms Research) lab under the supervision of Dr. Xin Yuan, my research activity revolves around the analysis, improvement and performance evaluation of a number of topology and routing schemes widely used in the eld of high performance computing. Over the years, I worked in a number of projects that is brie y described over the next few paragraphs. 1 LOAD BALANCED SLIM FLY NETWORKS The Slim Fly topology [2] has been proposed recently for future generation supercomputers. In this project, we investigated how the tra c is expected to disperse among the network, and discovered that in Slim Fly certain links are more likely to carry tra c than the rest of the links for both minimal and non minimal routing. As a result, hot spots are more likely to form in these links. To mitigate the issue, we came up with two di erent approaches. The rst approach, which we call the bandwidth provisioning scheme, is to modify the topology and increase the bandwidth of the overused links in such a rate so that the original load imbalance goes away. For a given Slim Fly topology, we identify the links that needs to get the added capacity, and the amount of extra bandwidth needed. This approach eliminates the load imbalance completely, but comes with implementation issues. The second approach, that we call the Weighted non minimal routing scheme, is to modify the non minimal routing to distribute the tra c in a more loadbalanced fashion. Essentially, we assigned some weights to the non minimal nodes to counter balance the inherent routing bias that comes with the topology. We presented two strategies to tune the necessary weights to implement this approach. We validated our resultswith detailed analysis and simulation, and demonstrated that both the approaches result in a more e ective Slim Fly network that its present form. 2 DRAGONFLY DESIGN SPACE: LINK ARRANGEMENT AND PATH DIVERSITY Dragon y [9] is a popular cost e ective interconnect design which has been used in a number of current and future generation supercomputers. In this topology, the nodes are grouped together into Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for pro t or commercial advantage and that copies bear this notice and the full citation on the rst page. Copyrights for third party components of this workmust be honored. For all other uses, contact the owner/author(s) ICPP'18, August 2018, Eugene, OR, USA (c) 2018 Copyright held by the owner/author(s) ACM ISBN 978 x xxxx xxxx x/YY/MM. https:/doi.org/10.1145/n clusters, and the clusters are connected to each other to form a diameter three network. The original Dragon y paper left a few issues open, like how the nodes inside the groups will be connected, towhich router and global channel should be connected to, orwhat happens when the total number of groups in the system is less than the maximum it can support. There has been e orts to answer these questions [5] and there are systems [4] that were built with deviations from the original Dragon y design, but there are still a lack of formal answers of the open questions. In this project, we investigate the design space of Dragon y. Our objective is twofold. First, we want to gure out how the inter group connections should be implemented to get optimum performance from the network, specially when the network contains less than maximum number of groups. Second, we analyze the minimal path distribution within the entire design space, and investigate the performance of the existing routing algorithms. This project is currently on going and we are using a number of modeling, simulation and learning techniques to attain our objectives. 3 TRAFFIC PATTERN BASED ADAPTIVE ROUTING IN DRAGONFLY NETWORKS In Dragon y topology, routing is done through minimal and nonminimal paths, and adaptive routing [13] is used to toggle between them. Traditionally, adaptive routing algorithms use locally available information, for example bu er queue length, to detect congestion scenario in the network. This poses a challenge for Dragon y as the inter group nodes may not have the most accurate information about congestion in the gateway routers. There have been a number of research [14] [8] on how to convey the congestion information e ciently to the local routers. For our project, we investigated the performance of adaptive routing in the Dragon y network used in Cray Cascade [4] and presented a novel scheme to improve over it. The idea is to gather link usage statistics through performance counters within a certain history window, and use that information to infer the tra c pattern: benign or adversarial. Then the nal routing decision is taken using both the tra c pattern and link load information. We performed simulation using a number of tra c patterns and demonstrated that our scheme achieves lower latency for benign tra c and higher throughput for adversarial tra c over the existing UGAL adaptive routing scheme. The rst phase of the project only considered the intra group communications. For the second phase, we are currently working to expand in to inter group communications as well. 4 PERFORMANCE MODELING STUDIES I worked in a number of projects over the years which analyzed and devised scalable modeling methods to evaluate various topologies, routings and performancemetrics. In one project,wemodeled ICPP'18, August 2018, Eugene, OR, USA Shafayat Rahman the UGAL[13] routing over Dragon y topology to get a better theoretical understanding on how the routing works. UGAL is extensively used on various systems to implement adaptive routing, but there had been no theoretical understanding on its e ectiveness; all the prior studies were simulation or experiment based. In our project, we modeled UGAL's performance with varying level of controls over the minimal and non minimal paths, and compared the modeling results with simulation output. The verdict was that individual level control on every path generally overestimates the system's output, full random control on all paths (basically treating each path as same) generally underestimates the output, and controlling the same length paths as a group goes within 10% of simulation output. So this gives a good estimation of system output under UGAL routing while is also computationally feasible. In another project, we evaluated a number of commonly used throughput models and identi ed similar and contradictory trends in their performance. The models we studied were max min fairness (MMF) [1] maximum concurrent ow (MCF) [12] Hoe er's method (HM) [6] and Jain's method (JM) [7] We showed that even though the later three models approximate MMF, they have subtle di erences and may even produce contradictory results depending on the topology and tra c pattern. Finally, Iworked in another project that studied the performance characteristics of a number of topologies that provide either low diameter (Dragon y and Slim Fly) or high path diversity (fat tree [11] RandomRegular graph [10] and Generalized De BruijnGraph [3] We investigated the performance of some HPC applications paired with some routing schemes on each of the topologies. We observed that the adaptive routing techniques developed for lowdiameter topologies are e ective on high path diversity topologies as well. Also, we determined that high path diversity topologies generally perform better than equivalent sized low diameter topologies. I started the program in FSU in 2011. I spent a number of years taking various core and elective courses, going through the PhD comprehensive exam, and exploring a number of research areas. I started working with Dr. Yuan from 2014. I acquired the background knowledge necessary to excel in the eld of HPC, completed my area exam and worked in a summer internship at Oak Ridge National Lab. I am on course to wrap up the current projects and complete my degree by the end of 2018. ACM Reference Format: Shafayat Rahman. 2018. Topologies and Adaptive Routing on large Scale Interconnects. In Proceedings of ACM Conference (ICPP'18) Eugene, OR, USA 2 pages. https:/doi.org/10.1145/n", "author_names": [ "Shafayat Rahman" ], "corpus_id": 123755054, "doc_id": "123755054", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Topologies and Adaptive Routing on large Scale Interconnects", "venue": "", "year": 2018 }, { "abstract": "BXI, Bull eXascale Interconnect, is the new inter connection network developed by Atos for High Performance Computing. It has been designed to meet the requirements of exascale supercomputers. At such scale, faults have to be expected and dealt with transparently so that applications remain unaffected by them. BXI features various mechanisms for this purpose, one of which is the BXI routing component presented in this paper. The BXI routing module computes the full routing tables for a 64k nodes fat tree in a few minutes. But with partial re computation it can withstand numerous inter router link failures without any noticeable impact on running applications.", "author_names": [ "Pierre Vigneras", "Jean-Noel Quintin" ], "corpus_id": 1165407, "doc_id": "1165407", "n_citations": 3, "n_key_citations": 2, "score": 0, "title": "Fault Tolerant Routing for Exascale Supercomputer: The BXI Routing Architecture", "venue": "2015 IEEE International Conference on Cluster Computing", "year": 2015 }, { "abstract": "Orthogonal fat trees are a type of interconnection network with several desirable characteristics: short distance between proceamrs, constant degree of the .switching elements, uniform traffic load, symmetry, and recursive scalability. We first show how to build two level orthogonal fat trees, where each node has a fixed degree and there is a maximum distance of two between any two leaves. We then show how to pm vide fault tolerance by including redundant paths at the cost of reducing the number of leaves. Finally, we &ow how to construct large orthogonal fat trees from two level fat trees recursively.", "author_names": [ "Marcos Valerio", "Louise E Moser", "P M Melliar-Smith" ], "corpus_id": 123949150, "doc_id": "123949150", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Interconnection Networks", "venue": "", "year": 1995 }, { "abstract": "We study recursive cube of rings (RCR) a class of scalable graphs that can potentially provide rich inter connection network topology for the emerging distributed and parallel computing infrastructure. Through rigorous proof and validating examples, we have corrected previous misunderstandings on the topological properties of these graphs, including node degree, symmetry, diameter and bisection width. To fully harness the potential of structural regularity through RCR construction, new edge connecting rules are proposed. The modified graphs, referred to as \\it Class II RCR} are shown to possess uniform node degrees, better connectivity and better network symmetry, and hence will find better application in parallel computing.", "author_names": [ "Kai Xie", "Jing Li", "Yumei Wang", "Chau Yuen" ], "corpus_id": 119607876, "doc_id": "119607876", "n_citations": 2, "n_key_citations": 2, "score": 0, "title": "Recursive Cube of Rings (RCR) Revisited: Properties and Enhancement", "venue": "", "year": 2013 }, { "abstract": "Interconnection networks of modern distributed computer systems are now hierarchical. In such systems communication time between processors depends on their placement in a computer system. In large scale NUMA/SMP computer clusters first two levels are formed by network switches of two stage fat tree/dragonfly topology and a third level is presented by a shared memory of computer nodes. In this paper, we describe a dynamic optimization method for collective all to all communication operations on hierarchical computer clusters. Our approach exploits knowledge of the L level hierarchy of a computer system and is based on a mapping of intensively communicating processes into the same computer nodes. Optimized versions of the Bruck and recursive doubling algorithms for MPI_Allgather operation are proposed. Algorithms are implemented in our experimental library TopoMPI. Performance results on multicore SMP computer clusters with InfiniBand and Gigabit Ethernet networks indicate that the Allgather algorithms based on our approach outperform the original Allgather algorithms (Bruck and recursive doubling)", "author_names": [ "Mikhail G Kurnosov" ], "corpus_id": 20733637, "doc_id": "20733637", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Dynamic mapping of all to all collective operations into hierarchical computer clusters", "venue": "2016 13th International Scientific Technical Conference on Actual Problems of Electronics Instrument Engineering (APEIE)", "year": 2016 } ]

[ { "abstract": "Realizing topological superconductivity and Majorana zero modes in the laboratory is a major goal in condensed matter physics. In this Review, we survey the current status of this rapidly developing field, focusing on proposals for the realization of topological superconductivity in semiconductor superconductor heterostructures. We examine materials science progress in growing InAs and InSb semiconductor nanowires and characterizing these systems. We then discuss the observation of robust signatures of Majorana zero modes in recent experiments, paying particular attention to zero bias tunnelling conduction measurements and Coulomb blockade experiments. We also outline several next generation experiments probing exotic properties of Majorana zero modes, including fusion rules and non Abelian exchange statistics. Finally, we discuss prospects for implementing Majorana based topological quantum computation.Realizing topological superconductivity and Majorana zero modes in the laboratory is a major goal in condensed matter physics. In this Review, the rapidly developing field is surveyed, with a focus on the realization of topological superconductivity in semiconductor superconductor heterostructures.", "author_names": [ "R M Lutchyn", "Erik P A M Bakkers", "L P Kouwenhoven", "Peter Krogstrup", "Charles M Marcus", "Yuval Oreg" ], "corpus_id": 73620367, "doc_id": "73620367", "n_citations": 468, "n_key_citations": 2, "score": 1, "title": "Majorana zero modes in superconductor semiconductor heterostructures", "venue": "Nature Reviews Materials", "year": 2018 }, { "abstract": "A topological superconductor A promising path toward topological quantum computing involves exotic quasiparticles called the Majorana bound states (MBSs) MBSs have been observed in heterostructures that require careful nanofabrication, but the complexity of such systems makes further progress tricky. Zhang et al. identified a topological superconductor in which MBSs may be observed in a simpler way by looking into the cores of vortices induced by an external magnetic field. Using angle resolved photoemission, the researchers found that the surface of the iron superconductor FeTe0.55Se0.45 satisfies the required conditions for topological superconductivity. Science, this issue p. 182 Angle resolved photoemission spectroscopy indicates that FeTe0.55Se0.45 harbors Dirac cone type spin helical surface states. Topological superconductors are predicted to host exotic Majorana states that obey non Abelian statistics and can be used to implement a topological quantum computer. Most of the proposed topological superconductors are realized in difficult to fabricate heterostructures at very low temperatures. By using high resolution spin resolved and angle resolved photoelectron spectroscopy, we find that the iron based superconductor FeTe1 xSex (x 0.45; superconducting transition temperature Tc 14.5 kelvin) hosts Dirac cone type spin helical surface states at the Fermi level; the surface states exhibit an s wave superconducting gap below Tc. Our study shows that the surface states of FeTe0.55Se0.45 are topologically superconducting, providing a simple and possibly high temperature platform for realizing Majorana states.", "author_names": [ "P Zhang", "Koichiro Yaji", "Takahiro Hashimoto", "Yuichi Ota", "Takeshi Kondo", "Kozo Okazaki", "Zhijun Wang", "Jinsheng Wen", "Genda Gu", "Hong Ding", "Shik Shin" ], "corpus_id": 206660109, "doc_id": "206660109", "n_citations": 277, "n_key_citations": 7, "score": 0, "title": "Observation of topological superconductivity on the surface of an iron based superconductor", "venue": "Science", "year": 2018 }, { "abstract": "An iron home for Majoranas The surface of the iron based superconductor FeTe0.55Se0.45 has been identified as a potential topological superconductor and is expected to host exotic quasiparticles called the Majorana bound states (MBSs) Wang et al. looked for signatures of MBSs in this material by using scanning tunneling spectroscopy on the vortex cores formed by the application of a magnetic field. In addition to conventional states, they observed the characteristic zero bias peaks associated with MBSs and were able to distinguish between the two, owing to the favorable ratios of energy scales in the system. Science, this issue p. 333 Scanning tunneling spectroscopy reveals signatures of Majorana bound states on the surface of FeTe1 xSex. The search for Majorana bound states (MBSs) has been fueled by the prospect of using their non Abelian statistics for robust quantum computation. Two dimensional superconducting topological materials have been predicted to host MBSs as zero energy modes in vortex cores. By using scanning tunneling spectroscopy on the superconducting Dirac surface state of the iron based superconductor FeTe0.55Se0.45, we observed a sharp zero bias peak inside a vortex core that does not split when moving away from the vortex center. The evolution of the peak under varying magnetic field, temperature, and tunneling barrier is consistent with the tunneling to a nearly pure MBS, separated from nontopological bound states. This observation offers a potential platform for realizing and manipulating MBSs at a relatively high temperature.", "author_names": [ "Dongfei Wang", "Lingyuan Kong", "Peng Fan", "Hui Chen", "Shiyu Zhu", "Wenyao Liu", "Lu Cao", "Yujie Sun", "Shixuan Du", "John A Schneeloch", "Ruidan Zhong", "Genda Gu", "Liang Fu", "Hong Ding", "Hongjun Gao" ], "corpus_id": 52021577, "doc_id": "52021577", "n_citations": 289, "n_key_citations": 4, "score": 0, "title": "Evidence for Majorana bound states in an iron based superconductor", "venue": "Science", "year": 2018 }, { "abstract": "A propagating Majorana mode Although Majorana fermions remain elusive as elementary particles, their solid state analogs have been observed in hybrid semiconductor superconductor nanowires. In a nanowire setting, the Majorana states are localized at the ends of the wire. He et al. built a two dimensional heterostructure in which a one dimensional Majorana mode is predicted to run along the sample edge (see the Perspective by Pribiag) The heterostructure consisted of a quantum anomalous Hall insulator (QAHI) bar contacted by a superconductor. The authors used an external magnetic field as a \"knob\" to tune into a regime where a Majorana mode was propagating along the edge of the QAHI bar covered by the superconductor. A signature of this propagation half quantized conductance was then observed in transport experiments. Science, this issue p. 294; see also p. 252 Transport experiments showing half integer quantized conductance indicate a propagating Majorana edge mode. Majorana fermion is a hypothetical particle that is its own antiparticle. We report transport measurements that suggest the existence of one dimensional chiral Majorana fermion modes in the hybrid system of a quantum anomalous Hall insulator thin film coupled with a superconductor. As the external magnetic field is swept, half integer quantized conductance plateaus are observed at the locations of magnetization reversals, giving a distinct signature of the Majorana fermion modes. This transport signature is reproducible over many magnetic field sweeps and appears at different temperatures. This finding may open up an avenue to control Majorana fermions for implementing robust topological quantum computing.", "author_names": [ "Qing Lin He", "Lei Pan", "Alex Stern", "Edward C Burks", "Xiaoyu Che", "Gen Yin", "Jing Wang", "Biao Lian", "Quan Zhou", "Eun Sang Choi", "Koichi Murata", "Xufeng Kou", "Zhijie Chen", "Tianxiao Nie", "Qiming Shao", "Yabin Fan", "Shou-Cheng Zhang", "Kai Liu", "Jing Xia", "Kang L Wang" ], "corpus_id": 3904085, "doc_id": "3904085", "n_citations": 380, "n_key_citations": 2, "score": 0, "title": "Chiral Majorana fermion modes in a quantum anomalous Hall insulator superconductor structure", "venue": "Science", "year": 2017 }, { "abstract": "Majoranas Arrive When a negatively charged electron meets a positron its positively charged antiparticle they annihilate each other in a flash of gamma rays. A Majorana fermion, on the other hand, is a neutral particle, which is its own antiparticle. No sightings of a Majorana have been reported in the elementary particle world, but recently they have been proposed to exist in solid state systems and suggested to be of interest as a quantum computing platform. Mourik et al. (p. 1003, published online 12 April; see the cover; see the Perspective by Brouwer) set up a semiconductor nanowire contacted on each end by a normal and a superconducting electrode that revealed evidence of Majorana fermions. Theoretically predicted particles that double as their own antiparticles emerge in a superconductor coupled indium antimonide nanowire. Majorana fermions are particles identical to their own antiparticles. They have been theoretically predicted to exist in topological superconductors. Here, we report electrical measurements on indium antimonide nanowires contacted with one normal (gold) and one superconducting (niobium titanium nitride) electrode. Gate voltages vary electron density and define a tunnel barrier between normal and superconducting contacts. In the presence of magnetic fields on the order of 100 millitesla, we observe bound, midgap states at zero bias voltage. These bound states remain fixed to zero bias, even when magnetic fields and gate voltages are changed over considerable ranges. Our observations support the hypothesis of Majorana fermions in nanowires coupled to superconductors.", "author_names": [ "Vincent Mourik", "Kun Zuo", "Sergey M Frolov", "Sebastien R Plissard", "Erik P A M Bakkers", "L P Kouwenhoven" ], "corpus_id": 18447180, "doc_id": "18447180", "n_citations": 2382, "n_key_citations": 36, "score": 0, "title": "Signatures of Majorana Fermions in Hybrid Superconductor Semiconductor Nanowire Devices", "venue": "Science", "year": 2012 }, { "abstract": "A possible sighting of Majorana states Nearly 80 years ago, the Italian physicist Ettore Majorana proposed the existence of an unusual type of particle that is its own antiparticle, the so called Majorana fermion. The search for a free Majorana fermion has so far been unsuccessful, but bound Majorana like collective excitations may exist in certain exotic superconductors. Nadj Perge et al. created such a topological superconductor by depositing iron atoms onto the surface of superconducting lead, forming atomic chains (see the Perspective by Lee) They then used a scanning tunneling microscope to observe enhanced conductance at the ends of these chains at zero energy, where theory predicts Majorana states should appear. Science, this issue p. 602; see also p. 547 Scanning tunneling microscopy is used to observe signatures of Majorana states at the ends of iron atom chains. [Also see Perspective by Lee] Majorana fermions are predicted to localize at the edge of a topological superconductor, a state of matter that can form when a ferromagnetic system is placed in proximity to a conventional superconductor with strong spin orbit interaction. With the goal of realizing a one dimensional topological superconductor, we have fabricated ferromagnetic iron (Fe) atomic chains on the surface of superconducting lead (Pb) Using high resolution spectroscopic imaging techniques, we show that the onset of superconductivity, which gaps the electronic density of states in the bulk of the Fe chains, is accompanied by the appearance of zero energy end states. This spatially resolved signature provides strong evidence, corroborated by other observations, for the formation of a topological phase and edge bound Majorana fermions in our atomic chains.", "author_names": [ "Stevan Nadj-Perge", "Ilya Drozdov", "Jian Li", "Hua Chen", "Sangjun Jeon", "Jungpil Seo", "Allan H MacDonald", "Bogdan Andrei Bernevig", "Ali Yazdani" ], "corpus_id": 206561257, "doc_id": "206561257", "n_citations": 1072, "n_key_citations": 12, "score": 0, "title": "Observation of Majorana fermions in ferromagnetic atomic chains on a superconductor", "venue": "Science", "year": 2014 }, { "abstract": "Recently, theory has predicted a Majorana zero mode (MZM) to induce spin selective Andreev reflection (SSAR) a novel magnetic property which can be used to detect the MZM. Here, spin polarized scanning tunneling microscopy or spectroscopy has been applied to probe SSAR of MZMs in a topological superconductor of the Bi_{2}Te_{3}/NbSe_{2} heterostructure. The zero bias peak of the tunneling differential conductance at the vortex center is observed substantially higher when the tip polarization and the external magnetic field are parallel rather than antiparallel to each other. This spin dependent tunneling effect provides direct evidence of MZM and reveals its magnetic property in addition to the zero energy modes. Our work will stimulate MZM research on these novel physical properties and, hence, is a step towards experimental study of their statistics and application in quantum computing.", "author_names": [ "Hao-Hua Sun", "Kaiwen Zhang", "Lunhui Hu", "Chuan Li", "Guan-Yong Wang", "Hai-Yang Ma", "Zhu-An Xu", "Chun-lei Gao", "Dandan Guan", "Yao-Yi Li", "Canhua Liu", "Dong Qian", "Yi Zhou", "Liang Fu", "Shao-Chun Li", "Fu-chun Zhang", "Jin-Feng Jia" ], "corpus_id": 45167305, "doc_id": "45167305", "n_citations": 310, "n_key_citations": 1, "score": 0, "title": "Majorana Zero Mode Detected with Spin Selective Andreev Reflection in the Vortex of a Topological Superconductor.", "venue": "Physical review letters", "year": 2016 }, { "abstract": "New data, backed up by simulations, support the existence of Majorana fermions in the one dimensional topological superconductor that is induced by placing an aluminium superconductor close to an indium arsenide nanowire.", "author_names": [ "Anindya Sundar Das", "Yuval Ronen", "Yonatan Most", "Yuval Oreg", "Moty Heiblum", "H Shtrikman" ], "corpus_id": 21753170, "doc_id": "21753170", "n_citations": 919, "n_key_citations": 14, "score": 0, "title": "Zero bias peaks and splitting in an Al InAs nanowire topological superconductor as a signature of Majorana fermions", "venue": "", "year": 2012 }, { "abstract": "Controlling the properties of semiconductor/metal interfaces is a powerful method for designing functionality and improving the performance of electrical devices. Recently semiconductor/superconductor hybrids have appeared as an important example where the atomic scale uniformity of the interface plays a key role in determining the quality of the induced superconducting gap. Here we present epitaxial growth of semiconductor metal core shell nanowires by molecular beam epitaxy, a method that provides a conceptually new route to controlled electrical contacting of nanostructures and the design of devices for specialized applications such as topological and gate controlled superconducting electronics. Our materials of choice, InAs/Al grown with epitaxially matched single plane interfaces, and alternative semiconductor/metal combinations allowing epitaxial interface matching in nanowires are discussed. We formulate the grain growth kinetics of the metal phase in general terms of continuum parameters and bicrystal symmetries. The method realizes the ultimate limit of uniform interfaces and seems to solve the soft gap problem in superconducting hybrid structures.", "author_names": [ "Peter Krogstrup", "N L B Ziino", "W Chang", "S M Albrecht", "Morten Hannibal Madsen", "Erik V Johnson", "Jesper Nygard", "Charles M Marcus", "Thomas Sand Jespersen" ], "corpus_id": 40745455, "doc_id": "40745455", "n_citations": 277, "n_key_citations": 7, "score": 0, "title": "Epitaxy of semiconductor superconductor nanowires.", "venue": "Nature materials", "year": 2015 }, { "abstract": "The fractional alternating current Josephson effect produces a series of steps in the current voltage characteristics of a superconducting junction driven at radiofrequencies. This unusual phenomenon is now observed in a semiconductor superconductor nanowire. What is more, a doubling in step size when a strong magnetic field is applied could be a possible signature of Majorana fermions, particles that are their own antiparticle.", "author_names": [ "Leonid P Rokhinson", "Xinyu Liu", "Jacek K Furdyna" ], "corpus_id": 34817629, "doc_id": "34817629", "n_citations": 525, "n_key_citations": 3, "score": 0, "title": "The fractional a.c. Josephson effect in a semiconductor superconductor nanowire as a signature of Majorana particles", "venue": "", "year": 2012 } ]

[ { "abstract": "Perovskite Photovoltaics For many types of low cost solar cells, including those using dye sensitized titania, performance is limited by low open circuit voltages. Lee et al. (p. 643, published online 4 October; see the Perspective by Norris and Aydil) have developed a solid state cell in which structured films of titania or alumina nanoparticles are solution coated with a lead halide perovskite layer that acts as the absorber and n type photoactive layer. These particles are coated with a spirobifluorene organic hole conductor in a solar cell with transparent oxide and metal contacts. For the alumina particles, power conversion efficiencies of up to 10.9% were obtained. Mesostructured alumina acts as an insulating scaffold for the assembly of very thin films of n and p type semiconductors. The energy costs associated with separating tightly bound excitons (photoinduced electron hole pairs) and extracting free charges from highly disordered low mobility networks represent fundamental losses for many low cost photovoltaic technologies. We report a low cost, solution processable solar cell, based on a highly crystalline perovskite absorber with intense visible to near infrared absorptivity, that has a power conversion efficiency of 10.9% in a single junction device under simulated full sunlight. This \"meso superstructured solar cell\" exhibits exceptionally few fundamental energy losses; it can generate open circuit photovoltages of more than 1.1 volts, despite the relatively narrow absorber band gap of 1.55 electron volts. The functionality arises from the use of mesoporous alumina as an inert scaffold that structures the absorber and forces electrons to reside in and be transported through the perovskite.", "author_names": [ "Michael M Lee", "Joel Teuscher", "Tsutomu Miyasaka", "Takurou N Murakami", "Henry J Snaith" ], "corpus_id": 37971858, "doc_id": "37971858", "n_citations": 7384, "n_key_citations": 55, "score": 1, "title": "Efficient Hybrid Solar Cells Based on Meso Superstructured Organometal Halide Perovskites", "venue": "Science", "year": 2012 }, { "abstract": "Following pioneering work, solution processable organic inorganic hybrid perovskites such as CH3NH3PbX3 (X Cl, Br, I) have attracted attention as light harvesting materials for mesoscopic solar cells. So far, the perovskite pigment has been deposited in a single step onto mesoporous metal oxide films using a mixture of PbX2 and CH3NH3X in a common solvent. However, the uncontrolled precipitation of the perovskite produces large morphological variations, resulting in a wide spread of photovoltaic performance in the resulting devices, which hampers the prospects for practical applications. Here we describe a sequential deposition method for the formation of the perovskite pigment within the porous metal oxide film. PbI2 is first introduced from solution into a nanoporous titanium dioxide film and subsequently transformed into the perovskite by exposing it to a solution of CH3NH3I. We find that the conversion occurs within the nanoporous host as soon as the two components come into contact, permitting much better control over the perovskite morphology than is possible with the previously employed route. Using this technique for the fabrication of solid state mesoscopic solar cells greatly increases the reproducibility of their performance and allows us to achieve a power conversion efficiency of approximately 15 per cent (measured under standard AM1.5G test conditions on solar zenith angle, solar light intensity and cell temperature) This two step method should provide new opportunities for the fabrication of solution processed photovoltaic cells with unprecedented power conversion efficiencies and high stability equal to or even greater than those of today's best thin film photovoltaic devices.", "author_names": [ "Julian Burschka", "Norman Pellet", "Soo-Jin Moon", "Robin A Humphry-Baker", "Peng Gao", "Mohammad Khaja Nazeeruddin", "Michael Gratzel" ], "corpus_id": 4348717, "doc_id": "4348717", "n_citations": 7089, "n_key_citations": 71, "score": 0, "title": "Sequential deposition as a route to high performance perovskite sensitized solar cells", "venue": "Nature", "year": 2013 }, { "abstract": "Many different photovoltaic technologies are being developed for large scale solar energy conversion. The wafer based first generation photovoltaic devices have been followed by thin film solid semiconductor absorber layers sandwiched between two charge selective contacts and nanostructured (or mesostructured) solar cells that rely on a distributed heterojunction to generate charge and to transport positive and negative charges in spatially separated phases. Although many materials have been used in nanostructured devices, the goal of attaining high efficiency thin film solar cells in such a way has yet to be achieved. Organometal halide perovskites have recently emerged as a promising material for high efficiency nanostructured devices. Here we show that nanostructuring is not necessary to achieve high efficiencies with this material: a simple planar heterojunction solar cell incorporating vapour deposited perovskite as the absorbing layer can have solar to electrical power conversion efficiencies of over 15 per cent (as measured under simulated full sunlight) This demonstrates that perovskite absorbers can function at the highest efficiencies in simplified device architectures, without the need for complex nanostructures.", "author_names": [ "Mingzhen Liu", "Michael B Johnston", "Henry J Snaith" ], "corpus_id": 205235359, "doc_id": "205235359", "n_citations": 5901, "n_key_citations": 52, "score": 0, "title": "Efficient planar heterojunction perovskite solar cells by vapour deposition", "venue": "Nature", "year": 2013 }, { "abstract": "Efficient all perovskite tandem cells Organic inorganic perovskite films can boost the output of conventional silicon solar cells in tandem geometries by utilizing more of the light at the blue end of the solar spectrum. Tandem cells that use only perovskite films have been less successful because of the lack of a suitable material with a low bandgap that can replace silicon. Tong et al. report that a mixed tin lead organic inorganic material containing a small fraction of guanidinium thiocyanate has a low bandgap, long charge carrier lifetime, and efficiencies around 25% Science, this issue p. 475 The addition of guanidinium thiocyanate improves the performance of mixed tin lead perovskite solar cells. All perovskite based polycrystalline thin film tandem solar cells have the potential to deliver efficiencies of >30% However, the performance of all perovskite based tandem devices has been limited by the lack of high efficiency, low band gap tin lead (Sn Pb) mixed perovskite solar cells (PSCs) We found that the addition of guanidinium thiocyanate (GuaSCN) resulted in marked improvements in the structural and optoelectronic properties of Sn Pb mixed, low band gap ~1.25 electron volt) perovskite films. The films have defect densities that are lower by a factor of 10, leading to carrier lifetimes of greater than 1 microsecond and diffusion lengths of 2.5 micrometers. These improved properties enable our demonstration of >20% efficient low band gap PSCs. When combined with wider band gap PSCs, we achieve 25% efficient four terminal and 23.1% efficient two terminal all perovskite based polycrystalline thin film tandem solar cells.", "author_names": [ "Jinhui Tong", "Zhaoning Song", "Dong Hoe Kim", "Xihan Chen", "Cong Chen", "Axel F Palmstrom", "Paul F Ndione", "Matthew O Reese", "Sean P Dunfield", "Obadiah G Reid", "Jun-ming Liu", "Fei Zhang", "Steven P Harvey", "Zhen Li", "Steven T Christensen", "Glenn Teeter", "Dewei Zhao", "Mowafak M Al-Jassim", "Maikel F A M van Hest", "Matthew C Beard", "Sean E Shaheen", "Joseph J Berry", "Yanfa Yan", "Kai Zhu" ], "corpus_id": 121619418, "doc_id": "121619418", "n_citations": 338, "n_key_citations": 1, "score": 0, "title": "Carrier lifetimes of >1 ms in Sn Pb perovskites enable efficient all perovskite tandem solar cells", "venue": "Science", "year": 2019 }, { "abstract": "All inorganic perovskites are considered to be one of the most appealing research hotspots in the field of perovskite photovoltaics in the past 3 years due to their superior thermal stability compared to their organic inorganic hybrid counterparts. The power conversion efficiency has reached 17.06% and the number of important publications is ever increasing. Here, the progress of inorganic perovskites is systematically highlighted, covering materials design, preparation of high quality perovskite films, and avoidance of phase instabilities. Inorganic perovskites, nanocrystals, quantum dots, and lead free compounds are discussed and the corresponding device performances are reviewed, which have been realized on both rigid and flexible substrates. Methods for stabilization of the cubic phase of low bandgap inorganic perovskites are emphasized, which is a prerequisite for highly efficient and stable solar cells. In addition, energy loss mechanisms both in the bulk of the perovskite and at the interfaces of perovskite and charge selective layers are unraveled. Reported approaches to reduce these charge carrier recombination losses are summarized and complemented by methods proposed from our side. Finally, the potential of inorganic perovskites as stable absorbers is assessed, which opens up new perspectives toward the commercialization of inorganic perovskite solar cells.", "author_names": [ "Wanchun Xiang", "Wolfgang R Tress" ], "corpus_id": 201804491, "doc_id": "201804491", "n_citations": 121, "n_key_citations": 0, "score": 0, "title": "Review on Recent Progress of All Inorganic Metal Halide Perovskites and Solar Cells.", "venue": "Advanced materials", "year": 2019 }, { "abstract": "Perovskites with bandgaps between 1.7 and 1.8 eV are optimal for tandem configurations with crystalline silicon (c Si) because they facilitate efficient harvest of solar energy. In that respect, achieving a high open circuit voltage (VOC) in such wide bandgap perovskite solar cells is crucial for a high overall power conversion efficiency (PCE) Here, we provide key insights into the factors affecting the VOC in wide bandgap perovskite solar cells. We show that the influence of the hole transport layer (HTL) on VOC is not simply through its ionization potential but mainly through the quality of the perovskite HTL interface. With effective interface passivation, we demonstrate perovskite solar cells with a bandgap of 1.72 eV that exhibit a VOC of 1.22 V. Furthermore, by combining the high VOC perovskite solar cell with a c Si solar cell, we demonstrate a perovskite Si four terminal tandem solar cell with a PCE of 27.1% exceeding the record PCE of single junction Si solar cells.", "author_names": [ "Manoj Jaysankar", "Benedito A L Raul", "Joao P Bastos", "Claire H Burgess", "Christ H L Weijtens", "Mariadriana Creatore", "Tom Aernouts", "Yinghuan Kuang", "Robert Gehlhaar", "Afshin Hadipour", "Jef Poortmans" ], "corpus_id": 139581714, "doc_id": "139581714", "n_citations": 69, "n_key_citations": 0, "score": 0, "title": "Minimizing voltage loss in wide bandgap perovskites for tandem solar cells", "venue": "", "year": 2019 }, { "abstract": "Two dimensional (2D) halide perovskites have recently emerged as a more stable and more versatile family of materials than three dimensional (3D) perovskite solar cell absorbers. Although solar cells made with 2D perovskites have yet to improve their power conversion efficiencies to compete with 3D perovskite solar cells, their immense diversity offers great opportunities and avenues for research that will likely close the gap between these two. Further, 2D perovskites can have various roles within a solar cell, either as the primary light absorber, as a capping layer, passivating layer, or within a mixed 2D/3D perovskite solar cell absorber. In this Minireview, we will review the history of 2D perovskites in solar cells, the relevant properties of such materials, the different roles that they can play in a solar cell, as well as current trends and challenges.", "author_names": [ "Carmen Ortiz-Cervantes", "Paulina Carmona-Monroy", "Diego Solis-Ibarra" ], "corpus_id": 73412438, "doc_id": "73412438", "n_citations": 66, "n_key_citations": 0, "score": 0, "title": "Two Dimensional Halide Perovskites in Solar Cells: 2D or not 2D?", "venue": "ChemSusChem", "year": 2019 }, { "abstract": "Researchers developed a perovskite solar cell with high power conversion efficiency >20% and intense electroluminescence yield (0.5% We report on a new metal halide perovskite photovoltaic cell that exhibits both very high solar to electric power conversion efficiency and intense electroluminescence. We produce the perovskite films in a single step from a solution containing a mixture of FAI, PbI2, MABr, and PbBr2 (where FA stands for formamidinium cations and MA stands for methylammonium cations) Using mesoporous TiO2 and Spiro OMeTAD as electron and hole specific contacts, respectively, we fabricate perovskite solar cells that achieve a maximum power conversion efficiency of 20.8% for a PbI2/FAI molar ratio of 1.05 in the precursor solution. Rietveld analysis of x ray diffraction data reveals that the excess PbI2 content incorporated into such a film is about 3 weight percent. Time resolved photoluminescence decay measurements show that the small excess of PbI2 suppresses nonradiative charge carrier recombination. This in turn augments the external electroluminescence quantum efficiency to values of about 0.5% a record for perovskite photovoltaics approaching that of the best silicon solar cells. Correspondingly, the open circuit photovoltage reaches 1.18 V under AM 1.5 sunlight.", "author_names": [ "Dongqin Bi", "Wolfgang R Tress", "M Ibrahim Dar", "Peng Gao", "Jingshan Luo", "Clementine Renevier", "Kurt Schenk", "Antonio Abate", "Fabrizio Giordano", "Juan Pablo Correa Baena", "Jean-David Decoppet", "Shaik Mohammed Zakeeruddin", "Mohammad Khaja Nazeeruddin", "Michael Gratzel", "Anders Hagfeldt" ], "corpus_id": 18307513, "doc_id": "18307513", "n_citations": 1359, "n_key_citations": 5, "score": 0, "title": "Efficient luminescent solar cells based on tailored mixed cation perovskites", "venue": "Science Advances", "year": 2016 }, { "abstract": "Owing to inevitable thermal/moisture instability for organic inorganic hybrid perovskites, pure inorganic perovskite cesium lead halides with both inherent stability and prominent photovoltaic performance have become research hotspots as a promising candidate for commercial perovskite solar cells. However, it is still a serious challenge to synthesize desired cubic cesium lead iodides (CsPbI3) with superior photovoltaic performance for its thermodynamically metastable characteristics. Herein, polymer poly vinylpyrrolidone (PVP) induced surface passivation engineering is reported to synthesize extra long term stable cubic CsPbI3. It is revealed that acylamino groups of PVP induce electron cloud density enhancement on the surface of CsPbI3, thus lowering surface energy, conducive to stabilize cubic CsPbI3 even in micrometer scale. The cubic CsPbI3 PSCs exhibit extra long carrier diffusion length (over 1.5 mm) highest power conversion efficiency of 10.74% and excellent thermal/moisture stability. This result provides important progress towards understanding of phase stability in realization of large scale preparations of efficient and stable inorganic PSCs.Inorganic cesium lead iodide perovskite is inherently more stable than the hybrid perovskites but it undergoes phase transition that degrades the solar cell performance. Here Li et al. stabilize it with poly vinylpyrrolidone and obtain high efficiency of 10.74% with excellent thermal and moisture stability.", "author_names": [ "Bo Li", "Yanan Zhang", "Lin Fu", "T F Yu", "Shujie Zhou", "Luyuan Zhang", "Longwei Yin" ], "corpus_id": 3844266, "doc_id": "3844266", "n_citations": 314, "n_key_citations": 2, "score": 0, "title": "Surface passivation engineering strategy to fully inorganic cubic CsPbI3 perovskites for high performance solar cells", "venue": "Nature Communications", "year": 2018 }, { "abstract": "Cesium based trihalide perovskites have been demonstrated as promising light absorbers for photovoltaic applications due to their superb composition stability. However, the large energy losses (Eloss observed in inorganic perovskite solar cells has become a major hindrance impairing the ultimate efficiency. Here, an effective and reproducible method of modifying the interface between a CsPbI2 Br absorber and polythiophene hole acceptor to minimize the Eloss is reported. It is demonstrated that polythiophene, deposited on the top of CsPbI2 Br, can significantly reduce electron hole recombination within the perovskite, which is due to the electronic passivation of surface defect states. In addition, the interfacial properties are improved by a simple annealing process, leading to significantly reduced energy disorder in polythiophene and enhanced hole injection into the hole acceptor. Consequently, one of the highest power conversion efficiency (PCE) of 12.02% from a reverse scan in inorganic mixed halide perovskite solar cells is obtained. Modifying the perovskite films with annealing polythiophene enables an open circuit voltage (VOC of up to 1.32 V and Eloss of down to 0.5 eV, which both are the optimal values reported among cesium lead mixed halide perovskite solar cells to date. This method provides a new route to further improve the efficiency of perovskite solar cells by minimizing the Eloss", "author_names": [ "Qingsen Zeng", "Xiaoyu Zhang", "Xiaolei Feng", "Siyu Lu", "Zhaolai Chen", "Xue Yong", "Simon A T Redfern", "Haotong Wei", "Haiyu Wang", "Huaizhong Shen", "Wei Zhang", "Weitao Zheng", "Hao Zhang", "John S Tse", "Bai Yang" ], "corpus_id": 3656578, "doc_id": "3656578", "n_citations": 264, "n_key_citations": 1, "score": 0, "title": "Polymer Passivated Inorganic Cesium Lead Mixed Halide Perovskites for Stable and Efficient Solar Cells with High Open Circuit Voltage over 1.3 V.", "venue": "Advanced materials", "year": 2018 } ]

[ { "abstract": "(NOTE: Each chapter concludes with Questions and Problems. 1. Wave Nature of Light. Light Waves in a Homogeneous Medium. Refractive Index. Group Velocity and Group Index. Magnetic Field, Irradiance and Poynting Vector. Snell's Law and Total Internal Reflection (TIR) Fresnel's Equations. Multiple Interference and Optical Resonators. Goos Hanchen and Optical Tunneling. Temporal and Spatial Coherence. Diffraction Principles. 2. Dielectric Waveguides and Optical Fibers. Symmetric Planar Dielectric Slab Waveguide. Modal and Waveguide Dispersion in the Planar Waveguide. Step Index Fiber. Numerical Aperture. Dispersion in Single Mode Fibers. Bit Rate, Dispersion, Electrical and Optical Bandwidth. The Graded Index Optical Fiber. Light Absorption and Scattering. Attenuation in Optical Fibers. Fiber Manufacture. 3. Semiconductor Science and Light Emitting Diodes. Semiconductor Concepts and Energy Bands. Direct and Indirect Bandgap Semiconductors: E k Diagrams. pn Junction Principles. The pn Junction Band Diagram. Light Emitting Diodes. LED Materials. Heterojunction High Intensity LEDs. LED Characteristics. LEDs for Optical Fiber Communications. 4. Stimulated Emission Devices Lasers. Stimulated Emission and Photon Amplification. Stimulated Emission Rate and Einstein Coefficients. Optical Fiber Amplifiers. Gas Laser: The He Ne Laser. The Output Spectrum of a Gas Laser. LASER Oscillation Conditions. Principle of the Laser Diode. Heterostructure Laser Diodes. Elementary Laser Diode Characteristics. Steady State Semiconductor Rate Equation. Light Emitters for Optical Fiber Communications. Single Frequency Solid State Lasers. Quantum Well Devices. Vertical Cavity Surface Emitting Lasers (VCSELs) Optical Laser Amplifiers. Holography. 5. Photodetectors. Principle of the pn Junction Photodiode. Ramo's Theorem and External Photocurrent. Absorption Coefficient and Photodiode Materials. Quantum Efficiency and Responsivity. The pin Photodiode. Avalanche Photodiode. Heterojunction Photodiodes. Phototransistors. Photoconductive Detectors and Photoconductive Gain. Noise in Photodetectors. 6. Photovoltaic Devices. Solar Energy Spectrum. Photovoltaic Device Principles. pn Junction Photovoltaic I V Characteristics. Series Resistance and Equivalent Circuit. Temperature Effects. Solar Cells Materials, Devices and Efficiencies. 7. Polarization and Modulation of Light. Polarization. Light Propagation in an Anisotropic Medium: Birefringence. Birefringent Optical Devices. Optical Activity and Circular Birefringence. Electro Optic Effects. Integrated Optical Modulators. Acousto Optic Modulator. Magneto Optic Effects. Non Linear Optics and Second Harmonic Generation. Notation and Abbreviations. Index. CD ROM: Optoelectronics and Photonics Contents.", "author_names": [ "Safa O Kasap" ], "corpus_id": 135738035, "doc_id": "135738035", "n_citations": 423, "n_key_citations": 43, "score": 1, "title": "Optoelectronics and Photonics: Principles and Practices", "venue": "", "year": 2001 }, { "abstract": "In this work, we report on the growth of high yield small bandgap InAs and InAsSb inserts embedded in InAsP nanowires grown on an InP substrate by catalyst free selective area metal organic chemical vapor deposition. It is observed that the growth of the inserts with high aspect ratios can be achieved by properly tuning the V/III ratio. Nanowire arrays with InAs(Sb) inserts exhibit strong photoluminescence at 77 K from interband transitions, spanning a wavelength range of 2.30 3.70 mm. In addition, the InAsP/InAs heterointerfaces are characterized by a scanning transmission electron microscope and an energy dispersive X ray spectroscopy. We believe that these results pave the way to engineering interband transitions and enabling hybrid integration for nanoscale optical devices at the mid wavelength infrared. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement OCIS codes: OCIS codes: (160.4236) Nanomaterials; (230.0250) Optoelectronics; (040.3060) Infrared. References and links 1. C. Li, Y. Zhang, K. Wang, Y. Gu, H. Li, and Y. Li, \"Distinction investigation of InGaAs photodetectors cutoff at 2.9 mm,\" Infrared Phys. Technol. 53(3) 173 176 (2010) 2. G. Hasnain, B. F. Levine, D. L. Sivco, and A. Y. Cho, \"Mid infrared detectors in the 3 5 mm band using bound to continuum state absorption in InGaAs/InAlAs multiquantum well structures,\" Appl. Phys. Lett. 56(8) 770 772 (1990) 3. B. Chen, W. Y. Jiang, J. Yuan, A. L. Holmes, Jr. and B. M. Onat, \"Demonstration of a room temperature InPbased photodetectors operating beyond 3mm,\" IEEE Photonics Technol. Lett. 23(4) 218 220 (2011) 4. B. Chen, W. Jiang, J. Yuan, A. L. Holmes, Jr. and B. M. Onat, \"SWIR/MWIR InP based p i n photodiodes with InGaAs/GaAsSb type II quantum wells,\" \" IEEE J. Quantum Electron. 47(9) 1244 1250 (2011) 5. B. Chen and A. L. Holmes, Jr. \"InP based short wave infrared and midwave infrared photodiodes using a novel type II strain compensated quantum well absorption region,\" Opt. Lett. 38(15) 2750 2753 (2013) 6. B. Chen, \"Active region design and gain characteristics of InP based dilute bismide type II quantum wells for mid IR lasers,\" IEEE Trans. Electron Dev. 64(4) 1606 1611 (2017) 7. S. R. Kurtz, A. A. Allerman, and R. M. Biefeld, \"Midinfrared lasers and light emitting diodes with InAsSb/InAsP strained layer superlattice active regions,\" Appl. Phys. Lett. 70(24) 3188 3190 (1997) 8. R. M. Biefeld, S. R. Kurtz, and A. A. Allerman, \"The metal organic chemical vapor deposition growth and properties of InAsSb mid infrared (3 6 mm) lasers and LED's,\" IEEE J. Sel. Top. Quantum Electron. 3(3) 739 748 (1997) 9. K. A. Dick and P. Caroff, \"Metal seeded growth of III V semiconductor nanowires: towards gold free synthesis,\" Nanoscale 6(6) 3006 3021 (2014) 10. D. Ren, A. C. Farrell, B. S. Williams, and D. L. Huffaker, \"Seeding layer assisted selective area growth of Asrich InAsP nanowires on InP substrates,\" Nanoscale 9(24) 8220 8228 (2017) 11. A. Behres, D. Puttjer, and K. Heime, \"Low pressure metal organic vapour phase epitaxy and characterization of strained InAs(P)/InAsSb superlattices for infrared emitters,\" J. Cryst. Growth 195(1 4) 373 377 (1998) 12. B. Lane, Z. Wu, A. Stein, J. Diaz, and M. Razeghi, \"InAsSb/InAsP strained layer superlattice injection lasers operation at 4.0 mm grown by metal organic chemical vapor deposition,\" Appl. Phys. Lett. 74(23) 3438 3440 (1999) 13. P. Christol, M. El Gazouli, P. Bigenwald, and A. Joullie, \"Performance simulation of 3.3 mm interband laser diodes grown on InAs substrate,\" Physica E 14(4) 375 384 (2002) Vol. 8, No. 4 1 Apr 2018 OPTICAL MATERIALS EXPRESS 1075 #320886 https:/doi.org/10.1364/OME.8.001075 Journal (c) 2018 Received 1 Feb 2018; revised 22 Mar 2018; accepted 25 Mar 2018; published 29 Mar 2018 14. C. Thelander, M. R. Bjork, M. W. Larsson, A. E. Hansen, L. R. Wallenberg, and L. Samuelson, \"Electron transport in InAs nanowires and heterostructure nanowire devices,\" Solid State Commun. 131(9 10) 573 579 (2004) 15. G. Nylund, K. Storm, S. Lehmann, F. Capasso, and L. Samuelson, \"Designed quasi 1D potential structures realized in compositionally graded InAs1 xPx nanowires,\" Nano Lett. 16(2) 1017 1021 (2016) 16. D. Ren, A. C. Farrell, and D. L. Huffaker, \"Selective area InAsSb nanowires on InP for 3 5 mm mid wavelength infrared optoelectronics,\" MRS Advances 2(58 59) 3565 3570 (2017) 17. S. A. Dayeh, E. T. Yu, and D. Wang, \"III V nanowire growth mechanism: V/III ratio and temperature effects,\" Nano Lett. 7(8) 2486 2490 (2007) 18. A. I. Persson, L. E. Froberg, S. Jeppesen, M. T. Bjork, and L. Samuelson, \"Surface diffusion effects on growth of nanowires by chemical bean epitaxy,\" J. Appl. Phys. 101(3) 034313 (2007) 19. S. Paiman, Q. Gao, H. J. Joyce, Y. Kim, H. H. Tan, C. Jagadish, X. Zhang, Y. Guo, and J. Zou, \"Growth temperature and V/III ratio effects on the morphology and crystal structure of InP nanowires,\" J. Phys. D Appl. Phys. 43(44) 445402 (2010) 20. K. Tomioka, J. Motohisa, S. Hara, and T. Fukui, \"Control of InAs nanowire growth directions on Si,\" Nano Lett. 8(10) 3475 3480 (2008) 21. A. Lin, J. N. Shapiro, A. C. Scofield, B. L. Liang, and D. L. Huffaker, \"Enhanced InAs nanopillar electrical transport by in situ passivation,\" Appl. Phys. Lett. 102(5) 053115 (2013) 22. M. Mattila, T. Hakkarainen, H. Lipasanen, H. Jiang, and E. I. Kauppinen, \"Catalyst free growth of In(As)P nanowires on silicon,\" Appl. Phys. Lett. 89(6) 063119 (2006) 23. J. Treu, M. Bormann, H. Schmeiduch, M. Doblinger, S. Morkotter, S. Matich, P. Wiecha, K. Saller, B. Mayer, M. Bichler, M. C. Amann, J. J. Finley, G. Abstreiter, and G. Koblmuller, \"Enhanced luminescence properties of InAs InAsP core shell nanowires,\" Nano Lett. 13(12) 6070 6077 (2013) 24. G. Landgren, P. Ojala, and O. Ekstrom, \"Influence of the gas switching sequence on the optical properties of ultrathin InGaAs/InP quantum wells,\" J. Cryst. Growth 107(1 4) 573 577 (1991) 25. H. A. McKay, R. M. Feenstra, P. J. Poole, and G. C. Aers, \"Cross sectional scanning tunneling microscopy studies of lattice matched InGaAs/InP quantum wells: variations in growth switching sequence,\" J. Cryst. Growth 249(3 4) 437 444 (2003) 26. A. C. Farrell, W. J. Lee, P. Senanayake, M. A. Haddad, S. V. Prikhodko, and D. L. Huffaker, \"High quality InAsSb nanowires grown by catalyst free selective area metal organic chemical vapor deposition,\" Nano Lett. 15(10) 6614 6619 (2015)", "author_names": [ "Claes Thelander", "Malin Bjork", "Magnus W Larsson", "A E Hansen", "L Reine Wallenberg", "Andrew Lin", "Joshua N Shapiro", "Adam C Scofield", "Stefanie Morkotter", "Sonja Matich", "Peter R Wiecha", "Kai Saller", "Benedikt F Mayer", "Martin Bichler", "Gerhard Abstreiter", "Gregor Koblmuller" ], "corpus_id": 4667756, "doc_id": "4667756", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Axial InAs Sb inserts in selective area InAsP nanowires on InP for optoelectronics beyond", "venue": "", "year": 2018 }, { "abstract": "Background Severity of illness scoring systems are widely used for quality assurance and research. Although validated by trained data collectors, there is little data on the accuracy of real world data collection practices. Objective To evaluate the influence of formal data collection training on the accuracy of scoring system data in intensive care units (ICUs) Study design and methods Quality assurance audit conducted using survey methodology principles. Between June and December 2018, an electronic document with details of three fictitious ICU patients was emailed to staff from 19 Australian ICUs who voluntarily submitted data on a web based data entry form. Their entries were used to generate severity of illness scores and risks of death (RoDs) for four scoring systems. The primary outcome was the variation of severity of illness scores and RoDs from a reference standard. Results 50/83 staff (60.3% submitted data. Using Bayesian multilevel analysis, severity of illness scores and RoDs were found to be significantly higher for untrained staff. The mean (95% high density interval) overestimation in RoD due to training effect for patients 1, 2 and 3, respectively, were 0.24 (0.16, 0.31) 0.19 (0.09, 0.29) and 0.24 (0.1, 0.38) respectively (Bayesian factor >300, decisive evidence) Both groups (trained and untrained) had wide coefficients of variation up to 38.1% indicating wide variability. Untrained staff made more errors in interpreting scoring system definitions. Interpretation In a fictitious patient dataset, data collection staff without formal training significantly overestimated the severity of illness scores and RoDs compared with trained staff. Both groups exhibited wide variability. Strategies to improve practice may include providing adequate training for all data collection staff, refresher training for previously trained staff and auditing the raw data submitted by individual ICUs. The results of this simulated study need revalidation on real patients.", "author_names": [ "Arvind Rajamani", "Stephen J Huang", "Ashwin Subramaniam", "Michele Thomson", "Jinghang Luo", "Andrew Simpson", "Anthony S McLean", "Anders Aneman", "Thodur Vinodh Madapusi", "Ramanathan Lakshmanan", "Gordon Flynn", "Latesh Poojara", "Jonathan J Gatward", "Raju Pusapati", "Adam E Howard", "Debbie Odlum" ], "corpus_id": 214748180, "doc_id": "214748180", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Evaluating the influence of data collector training for predictive risk of death models: an observational study", "venue": "BMJ Quality Safety", "year": 2020 }, { "abstract": "Foreword Contributors 1. Introduction: Setting the Scene for Transboundary Water Management Approaches Part I: Analytical Approaches to Transboundary Water Management 2. Why Negotiate? Asymmetric endowments and asymmetric power and the invisible nexus of water, trade and power that brings apparent water security 3. Power, Hegemony and Critical Hydropolitics 4. Getting Beyond the Environment Conflict Trap: Benefit Sharing in International River Basins Part II: Transboundary Water Management Polity and Practice 5. International Water Law: concepts, evolution and development 6. Aquifer Resources in a Transboundary Context: A Hidden Resource? Enabling the Practitioner To 'See It Bank It' for Good Use 7. Governance in Transboundary Basins the Role of Stakeholders, Concepts and Approaches in International River Basins 8. Environmental Flows in Shared Watercourses: Review of Assessment Methods and Relevance in the Transboundary Setting 9. Managing Water Negotiations and Conflicts in Concept and in Practice 10. Identifying Business Models for Transboundary River Basin Institutions Part III: Challenges and Opportunities 11. Sustainability of Transnational Water Agreements in the Face of Socio Economic and Environmental Change 12. Enhanced Knowledge and Education Systems for Strengthening the Capacity of Transboundary Water Management 13. Case studies of TWM Initiatives: 13 initiatives from various parts of the world 14. Towards a Conceptual Framework for Transboundary Water Management Index", "author_names": [ "Anton Earle", "Anders Jagerskog", "Joakim Ojendal" ], "corpus_id": 127976606, "doc_id": "127976606", "n_citations": 54, "n_key_citations": 2, "score": 0, "title": "Transboundary water management principles and practice", "venue": "", "year": 2010 }, { "abstract": "Following approval of the ICD 11 by the World Health Assembly in May 2019, World Health Organization (WHO) member states will transition from the ICD 10 to the ICD 11, with reporting of health statistics based on the new system to begin on January 1, 2022. The WHO Department of Mental Health and Substance Abuse will publish Clinical Descriptions and Diagnostic Guidelines (CDDG) for ICD 11 Mental, Behavioural and Neurodevelopmental Disorders following ICD 11's approval. The development of the ICD 11 CDDG over the past decade, based on the principles of clinical utility and global applicability, has been the most broadly international, multilingual, multidisciplinary and participative revision process ever implemented for a classification of mental disorders. Innovations in the ICD 11 include the provision of consistent and systematically characterized information, the adoption of a lifespan approach, and culture related guidance for each disorder. Dimensional approaches have been incorporated into the classification, particularly for personality disorders and primary psychotic disorders, in ways that are consistent with current evidence, are more compatible with recovery based approaches, eliminate artificial comorbidity, and more effectively capture changes over time. Here we describe major changes to the structure of the ICD 11 classification of mental disorders as compared to the ICD 10, and the development of two new ICD 11 chapters relevant to mental health practice. We illustrate a set of new categories that have been added to the ICD 11 and present the rationale for their inclusion. Finally, we provide a description of the important changes that have been made in each ICD 11 disorder grouping. This information is intended to be useful for both clinicians and researchers in orienting themselves to the ICD 11 and in preparing for implementation in their own professional contexts.", "author_names": [ "Geoffrey M Reed", "Michael First", "Cary S Kogan", "Steven E Hyman", "Oye Gureje", "Wolfgang Gaebel", "Mario Maj", "Dan J Stein", "Andreas Maercker", "Peter Tyrer", "Angelica M Claudino", "Elena Garralda", "Luis Salvador-Carulla", "R Ray", "John B Saunders", "Tarun Dua", "Vladimir Poznyak", "Maria Elena Medina-Mora", "Kathleen M Pike", "Jose Luis Ayuso-Mateos", "Shigenobu Kanba", "Jared Wayne Keeley", "Brigitte Khoury", "Valery N Krasnov", "Maya A Kulygina", "Anne M Lovell", "Jair de Jesus Mari", "Toshimasa Maruta", "Chihiro Matsumoto", "Tahilia J Rebello", "Michael C Roberts", "Rebeca Robles", "Pratap Sharan", "Min Zhao", "Assen A Jablensky", "Pichet Udomratn", "Afarin Rahimi-Movaghar", "Per-Anders Rydelius", "Sabine Bahrer-Kohler", "Ann D Watts", "Shekhar Saxena" ], "corpus_id": 58568160, "doc_id": "58568160", "n_citations": 256, "n_key_citations": 6, "score": 0, "title": "Innovations and changes in the ICD 11 classification of mental, behavioural and neurodevelopmental disorders", "venue": "World psychiatry official journal of the World Psychiatric Association", "year": 2019 }, { "abstract": "We have demonstrated a CMOS Optoelectronic technology platform, using a 650mW 4x10 Gb/s 0.13 mm silicon on insulator integrated transceiver chip, co packaged with an externally modulated laser, to enable high density data interconnects at $1 per Gbps.", "author_names": [ "Adithyaram Narasimha", "Sherif Abdalla", "Colin Bradbury", "Aaron Clark", "Jim Clymore", "James Coyne", "A Dahl", "Steffen Gloeckner", "Alberto Gruenberg", "Drew Guckenberger", "Steve Gutierrez", "Mark Harrison", "Daniel Kucharski", "Kosal Leap", "R LeBlanc", "Yi Liang", "Michael Mack", "D Martinez", "Gianlorenzo Masini", "Attila Mekis", "Ron Menigoz", "C Ogden", "Mark Peterson", "Thierry Pinguet", "J Redman", "Jose Rodriguez", "Subal Sahni", "M Sharp", "Thomas J Sleboda", "D Song", "Yanxin Wang", "Brian Welch", "Jeremy Witzens", "Wei Xu", "K Yokoyama", "Peter M De Dobbelaere" ], "corpus_id": 31971336, "doc_id": "31971336", "n_citations": 57, "n_key_citations": 2, "score": 0, "title": "An ultra low power CMOS photonics technology platform for H/S optoelectronic transceivers at less than $1 per Gbps", "venue": "2010 Conference on Optical Fiber Communication (OFC/NFOEC) collocated National Fiber Optic Engineers Conference", "year": 2010 }, { "abstract": "Background: The first report of patellofemoral arthroplasty (PFA) was published in 19791. Reviews in 2005 and 20072,3 called for studies comparing PFA with total knee arthroplasty (TKA) for isolated patellofemoral osteoarthritis. A blinded randomized controlled trial (RCT) was initiated in 2007 for this purpose, and the first report with 2 year results was awarded the Mark Coventry Award of the Knee Society in 20174. It was found that (1) patients recover more quickly from PFA than from TKA; (2) during the first 2 years after surgery, PFA treated patients have better average knee function than TKA treated patients; and (3) PFA treated patients regain their preoperative range of movement within the first postoperative year whereas TKA treated patients do not regain it within the first 2 years4. Description: There are general principles that are common to all brands of PFA implants. These include (1) an indication based on bone on bone contact in the patellofemoral joint with a preserved tibiofemoral joint; (2) replacing all surfaces of the patellofemoral joint, with metal on the femoral side and polyethylene on the patellar side; (3) ensuring a smooth transition from normal articular cartilage to the trochlear component; and (4) creating normal patellofemoral tracking. Alternatives: The primary treatment of any degenerative condition should be nonoperative, but when such measures are insufficient surgical treatment may be indicated. Many procedures have been suggested for relieving patellofemoral pain, but if there is bone on bone contact in the patellofemoral joint, the only current surgical option (except for experimental treatments) is joint replacement i.e. either PFA or TKA. Rationale: Our general principle for joint replacement of the knee is to replace only the affected compartment if unicompartmental changes are found. If =2 compartments are affected, we perform TKA. This principle is challenged both by proponents of performing TKA in all cases of knee osteoarthritis and by proponents of bicompartmental knee replacement for 2 compartment disease. The 2 year results of our blinded RCT comparing PFA and TKA4 support our current practice of PFA. In our practice, we have found PFA to be a rewarding procedure when the correct indications are used. PFA is likely to remain a fairly rare procedure, but any knee arthroplasty center should be able to offer it.", "author_names": [ "Anders Odgaard", "Jonathan D J Eldridge", "Frank Madsen" ], "corpus_id": 199470596, "doc_id": "199470596", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Patellofemoral Arthroplasty", "venue": "JBJS essential surgical techniques", "year": 2019 }, { "abstract": "This paper follows the unfolding legal controversy between Scandinavian Airlines System (SAS) and the Swedish Competition Authority (SCA) regarding the formers' frequent flyer program (FFP) entitled EuroBonus. The controversy arises in late 1999 as SCA finds SAS' application of EuroBonus in Sweden to be at odds with the Swedish Competition Act (SFS 1993:20) article 19 on abuse of a dominant position. The dispute is settled in early 2001 as the Swedish Market court rules largely in favor of SCA. SAS is prohibited from applying its EuroBonus program on those domestic routes where there is competition. Although the case hosts an array of intriguing topics, e.g. defining the relevant market and determining dominance, this text revolves around the issue of abuse. Assuming that SAS is a dominant actor in the defined market, the key concern is then whether its frequent flyer program, EuroBonus, simply embodies everyday market practice in air travel or if it constitutes abuse of a dominant position. This means that two interpretations of the EuroBonus program clash against each other as the parties present their arguments: on the one hand, an everyday market behavior practiced by SAS; on the other, a deviation from the ideal type market conduct promoted by SCA. The paper seeks to contribute to our understanding of the interrelation between ideas and principles concerning markets and marketing on the one hand, and market(ing) practice on the other. This topic is increasingly attended to also outside of marketing (see, e.g. Callon 1998) It is one particular such tradition that has inspired our method for mapping the controversy between practices and principles, the sociology of science and techniques (confer Law (1986, 1994) Latour (1987, 1996) Most importantly, we switch from an ostensive definition of the world to a performative ditto. From this perspective, the controversy concerning the EuroBonus program can be seen as a series of attempted translations (confer Latour (1987) through which the parties seek to manifest their respective views before the court. These translations together *[email protected], [email protected] form a framing process (confer Callon 1998, Goffman 1986) through which the parties seek to add reality to their particular reading of the situation. The ruling arrived at by the Market court (MD 2001:4) stabilizes the controversy, at least for some time, since emergent FFP practices and potential controversies associated with these are likely to perform the market in other ways yet. The text is divided into four main parts. Initially, the perspective adhered to, a performative view of market action, is presented together with its implication for how we choose to delineate the controversy. We then briefly look at the relevant legislation, and then at a few general accounts of the particular marketing practice under study, i.e. the enforcement of customer loyalty. In the next part, the case is presented. There, the two parties are invited to present their respective positions, and the Market court its motives for the final ruling. We conclude by discussing how this ruling still is but a temporary stabilization of FFP practice. A performative view of markets and marketing How can the interrelation between market(ing) principles and market(ing) practice be studied? In this paper, we use an approach developed within the sociology of science and techniques for studying how scientific facts are established (see, e.g. Law 1986, 1994; Latour 1987, 1996) To date, the perspective has had a limited impact on research in the field of marketing (but see Kjellberg 2001; Kjellberg and Andersson 2003) A central aspect of this approach is a shift from an ostensive to a performative definition of the world (Latour 1986) Underlying the performative definition is an ontological assumption of variability, that is, the world is not assumed to be characterised by stable principles, but rather by changing practices. A methodological consequence of this is that we allow the involved actors to define each other as well as the relevant aspects of their world, and that we follow the efforts of these actors to realise their version. This is possible since we study a controversy which involves questions regarding the constitution of (market ing) reality. To understand how this situation unfolds, we would be ill adviced to apply an elaborate theoretical framework that establishes a priori what the world under study is or is not like (Latour 1987) Constructing the narrative In line with this position, we have constructed our narrative using the official documents exchanged, most often petitions 'pronouncements' filed with the Market court. Since SAS files an appeal that urges the Market court to invalidate the original decision taken by SCA (which is where our story takes off) the first part of the account actually takes place outside the courtroom. It involves an exchange of views that could be called the 'preparatory controversy' which ultimately is settled in court during the main proceedings. The resulting narrative is not intended to be descriptive, but has been 'designed to isolate the features that are crucial for a particular problem' (Friedman 1953, p 36) largely like one of Weber's ideal types. In our case, the problem of interest is the interrelation of market(ing) practice and market(ing) principles, particularly the evaluation of EuroBonus according to the principles of Swedish antitrust legislation. Hence, the narrative is not exhaustive; we limit ourselves to the issue of abuse, and apply our own judgments as to the relevance of various aspects for this particular issue. As discussed above, however, in determining the relevance of any specific aspect, we have strived to 'follow the actors' That is, we have sought to apply their frames of reference and to reflect their views. Devising a possible explanatory scheme Through an abductive process (Alvesson and Skoldberg 1994) we subsequently propose a vocabulary for interpreting our case. That is, we seek to combine insights from following how this particular controversy unfolds with concepts and ideas that have been suggested in studies of other kinds of controversies. We make no claims as to the possibility of generalising the specific conclusions from our particular case. However, the concepts that we use are sufficiently general to be applicable when analysing other types of market(ing) controversies, including ones that take place outside the realm of a legal dispute. The Swedish Competition Act and abuse of dominant position The Swedish Competition Act (SFS 1993:20) resulted from a translation of the European antitrust legislation. Just as its main source of inspiration, the Swedish text revolves around two major restraints on competition, collaboration between companies (article 6) and abuse of a dominant market position (article 19) According to the latter, companies and/or associations of companies are not allowed to abuse, horizontally or vertically, a dominant position on the relevant market (where dominance refers to their market shares) Unlawful conduct is sanctioned, e.g. through a conditional fine should the company not immediately discontinue a particular abusive market behavior. Figure 1; Article 19 of the Swedish Competition Act (SFS 1993:20) [Article 19] Any abuse by one or more undertakings of a dominant position on the market shall be prohibited. Such abuse may, in particular, consist in 1. directly or indirectly imposing unfair purchase or selling prices or other unfair trading conditions; 2. limiting production, markets or technological development to the prejudice of consumers; 3. applying dissimilar conditions to equivalent transactions with other trading parties, thereby placing them at a competitive disadvantage; or 4. making the conclusion of contracts subject to acceptance by the other parties of supplementary obligations, which by their nature or according to commercial usage have no connection with the subject of such contracts. Article 19 stipulates as unlawful gains from abusive behaviour, once it can be established that a company (or an association of companies) occupies a dominant market position. That is to say, dominance is a necessary but not sufficient criterion for the article to be applicable. It is not abusive to be dominant per se. But the way in which such a position of market power might in fact be used 'horizontally' and/or 'vertically' to the unlawful disadvantage of others, is (Konkurrensverket 2003) As furthermore learned from Figure 1, four cases of possible abuse can be identified. On the one hand there can be 'exploitative abuse' according to which an own market position is drawn upon to directly further one's own interests; customers are hurt (the first two examples) On the other hand abuse can be 'exclusionary' meaning that competitors are directly hurt by a company that holds a dominant market position (the last two examples) So both short term direct (exclusionary) and long term indirect (exploitative) potential harm to customers and competitors are covered by the article. As figure 1 shows, the law does not specifically define abuse. Rather, the presence of abuse should be determined with reference to the particular context in each individual case (Carlsson et al 1995, p 334, Bernitz 1996, p 58, Korah 1997, pp 3 4, Wetter et al 1999, pp 419 420) Loyalty programs as a facet of relationship marketing The gradual development of individual exchange transactions into exchange relations is by no means a novel aspect of the economy. Replacing the transaction with the relation Konkurrensverket 2003 as the focal point of attention involves interweaving the past, present, and future and Although an empirical reality since long (confer Johanson 1966, Hammarkvist et al 198 y work early 1970s and onwards (confer Scott 1991) In thi characterized by increased competition and technology tha", "author_names": [ "Hans Kjellberg", "Anders Liljenberg" ], "corpus_id": 199389975, "doc_id": "199389975", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Marketing on trial practices and principles in the case of SAS EuroBonus program Abstract", "venue": "", "year": 2005 }, { "abstract": "ObjectiveTo report the ESICM consensus and clinical practice recommendations on fluid therapy in neurointensive care patients.DesignA consensus committee comprising 22 international experts met in October 2016 during ESICM LIVES2016. Teleconferences and electronic based discussions between the members of the committee subsequently served to discuss and develop the consensus process.MethodsPopulation, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles generated. The consensus focused on three main topics: (1) general fluid resuscitation and maintenance in neurointensive care patients, (2) hyperosmolar fluids for intracranial pressure control, (3) fluid management in delayed cerebral ischemia after subarachnoid haemorrhage. After an extensive literature search, the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system were applied to assess the quality of evidence (from high to very low) to formulate treatment recommendations as strong or weak, and to issue best practice statements when applicable. A modified Delphi process based on the integration of evidence provided by the literature and expert opinions using a sequential approach to avoid biases and misinterpretations was used to generate the final consensus statement.ResultsThe final consensus comprises a total of 32 statements, including 13 strong recommendations and 17 weak recommendations. No recommendations were provided for two statements.ConclusionsWe present a consensus statement and clinical practice recommendations on fluid therapy for neurointensive care patients.", "author_names": [ "Mauro Oddo", "Daniele Poole", "Raimund Helbok", "Geert Meyfroidt", "Nino Stocchetti", "Pierre Bouzat", "Maurizio Cecconi", "Thomas Geeraerts", "Ignacio Martin-Loeches", "Herve Quintard", "Fabio Silvio Taccone", "Romergryko G Geocadin", "Claude Hemphill", "Carole Ichai", "David K Menon", "Jean-Francois Payen", "Anders Perner", "Martin Smith", "Jose I Suarez", "Walter Videtta", "Elisa R Zanier", "Giuseppe Citerio" ], "corpus_id": 3646923, "doc_id": "3646923", "n_citations": 59, "n_key_citations": 1, "score": 0, "title": "Fluid therapy in neurointensive care patients: ESICM consensus and clinical practice recommendations", "venue": "Intensive Care Medicine", "year": 2018 }, { "abstract": "BACKGROUND Usual medical care in the United States is frequently not a satisfying experience for either patients or primary care physicians. Whether primary care can be saved and its quality improved is a subject of national concern. An increasing number of physicians are using microsystem principles to radically redesign their practices. Small, independent practices micro practices are often able to incorporate into a few people the frontline attributes of successful microsystems such as clear leadership, patient focus, process improvement, performance patterns, and information technology. PATIENT FOCUS, PROCESS IMPROVEMENT, AND PERFORMANCE PATTERNS An exemplary microsystem will (1) have as its primary purpose a focus on the patient a commitment to meet all patient needs; (2) make fundamental to its work the study, measurement, and improvement ofcare a commitment to process improvement; and (3) routinely measure its patterns of performance, \"feed back\" the data, and make changes based on the data. LESSONS FROM MICRO PRACTICES The literature and experience with micro practices suggest that they (1) constitute an important group in which to demonstrate the value of microsystem thinking; (2) can become very effective clinical microsystems; (3) can reduce their overhead costs to half that of larger freestanding practices, enabling them to spend more time working with their patients; (4) can develop new tools and approaches without going through layers of clearance; and (5) need not reinvent the wheel. CONCLUSIONS Patient reported data demonstrate how micro practices are using patient focus, process improvement, performance patterns, and information technology to improve performance. Pati ents should be able to report that they receive \"exactly the care they want and need exactly when and how they want and need it.\"", "author_names": [ "John H Wasson", "Scott Anders", "L Gordon Moore", "Lynn Ho", "Eugene C Nelson", "Marjorie M Godfrey", "Paul B Batalden" ], "corpus_id": 33715352, "doc_id": "33715352", "n_citations": 43, "n_key_citations": 3, "score": 0, "title": "Clinical microsystems, part 2. Learning from micro practices about providing patients the care they want and need.", "venue": "Joint Commission journal on quality and patient safety", "year": 2008 } ]

[ { "abstract": "A novel technique for optical injection locking of two semiconductor lasers through high order Brillouin Stokes components in optical fiber is proposed and experimentally demonstrated. The configuration potentially provides microwave signals generation at manifold Brillouin frequency without high frequency external modulator and generator. Significant narrowing of the locked slave semiconductor laser linewidth was recorded.", "author_names": [ "Vasily V Spirin", "Marcial Castro", "Cesar A Lopez-Mercado", "Patrice Megret", "Andrei A Fotiadi" ], "corpus_id": 121680720, "doc_id": "121680720", "n_citations": 20, "n_key_citations": 0, "score": 1, "title": "Optical locking of two semiconductor lasers through high order Brillouin Stokes components in optical fiber", "venue": "", "year": 2012 }, { "abstract": "ZnSe and other zinc chalcogenide semiconductor materials can be doped with divalent transition metal ions to create a mid IR laser gain medium with active function in the wavelength range 2 5 microns and potentially beyond using frequency conversion. As a step towards fiberized laser devices, we have manufactured ZnSe semiconductor fiber waveguides with low (less than 1dB/cm at 1550nm) optical losses, as well as more complex ternary alloys with ZnSxSe(1 x) stoichiometry to potentially allow for annular heterostructures with effective and low order mode corecladding waveguiding.", "author_names": [ "Pier J A Sazio", "Justin R Sparks", "Rongrui He", "Mahesh Krishnamurthi", "Thomas C Fitzgibbons", "Subhasis Chaudhuri", "Neil F Baril", "Anna C Peacock", "Noel Healy", "Venkatraman Gopalan", "John V Badding" ], "corpus_id": 37973694, "doc_id": "37973694", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Templated growth of II VI semiconductor optical fiber devices and steps towards infrared fiber lasers", "venue": "Photonics West Lasers and Applications in Science and Engineering", "year": 2015 }, { "abstract": "We present the modeling on high speed modulation of semiconductor lasers beyond 50 GHz over a frequency band of 2 GHz by using strong optical feedback (OFB) This ultra high modulation frequency is achieved by adjusting the external cavity resonance frequency close to the modulation frequency and optimizing strong OFB conditions to achieve stable operation. We show that this optimized strong OFB results in about 20 dB improvement in the link gain of a 55.8 GHz radio over fiber (RoF) link. We also discuss the influence of environmental variations on the simulated modulation characteristics.", "author_names": [ "Moustafa Ahmed", "Ahmed Bakry", "Reem M Al-Tuwirqi", "Mohamed S Alghamdi", "Fumio Koyama" ], "corpus_id": 119539555, "doc_id": "119539555", "n_citations": 21, "n_key_citations": 1, "score": 0, "title": "Enhancing Modulation Bandwidth of Semiconductor Lasers beyond 50 GHz by Strong Optical Feedback for Use in Millimeter Wave Radio over Fiber Links", "venue": "", "year": 2013 }, { "abstract": "Using a fiber optic temperature sensing system based on the cross correlation of picosecond optical pulses from a gain switched semiconductor laser, the thermal time constants of several types of optical fiber in water were measured.", "author_names": [ "Kazunari Tokunaga", "Yoshitaka Naito", "Tetsuya Matsuyama" ], "corpus_id": 225398820, "doc_id": "225398820", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Measurement of thermal time constant of optical fiber using linear cross correlation of optical pulses", "venue": "2020 Conference on Lasers and Electro Optics Pacific Rim (CLEO PR)", "year": 2020 }, { "abstract": "To distribute microwaves over fibers, optical single sideband (SSB) modulation signals are preferred to optical double sideband (DSB) modulation signals. This study investigates an optically injected semiconductor laser at period one nonlinear dynamics for optical DSB to SSB conversion. For the operating microwave frequencies up to 40 GHz investigated in this study, the proposed system regenerates or even enhances the microwave features of an optical DSB input while converting its optical feature into SSB with an intensity difference of at least 20 dB. The bit error ratio at 622 Mb/s is down to 10( 9) with a sensitivity improvement of up to 3 dB. The proposed system can be self adapted to certain changes in the operating microwave frequency and can operate stably under certain fluctuations in the input optical power and frequency.", "author_names": [ "Yu-Han Hung", "Cheng-Hao Chu", "Sheng-Kwang Hwang" ], "corpus_id": 8287627, "doc_id": "8287627", "n_citations": 42, "n_key_citations": 0, "score": 0, "title": "Optical double sideband modulation to single sideband modulation conversion using period one nonlinear dynamics of semiconductor lasers for radio over fiber links.", "venue": "Optics letters", "year": 2013 }, { "abstract": "This paper introduces an integrated fiber physical unclonable function (PUF) verification system based on a semiconductor laser source at substantially lower complexity and cost than existing alternatives. A source sub section consisting of a linear frequency swept semiconductor laser is used in combination with an optical frequency domain reflectometry (OFDR)/LiDAR based measurement sub section in order to conduct fiber identification via measurement of the unique Rayleigh reflection pattern of a section of optical fiber. When using these Rayleigh reflection patterns as PUFs, this technique results in a maximum equal error rate (EER) of 0.15% for a 5 cm section of optical fiber and an EER of less than 1% for a 4 cm section. These results demonstrate that the system can serve as a robust method fiber identification for device and communication verification applications.", "author_names": [ "Zheyi Yao", "Thomas Mauldin", "Gerald Hefferman", "Zheyu Xu", "Ming Liu", "Tao Wei" ], "corpus_id": 201258594, "doc_id": "201258594", "n_citations": 7, "n_key_citations": 1, "score": 0, "title": "Low cost optical fiber physical unclonable function reader based on a digitally integrated semiconductor LiDAR.", "venue": "Applied optics", "year": 2019 }, { "abstract": "To mitigate power fading of microwaves over fiber distribution, a scheme for optical double to single sideband conversion is proposed using semiconductor lasers at stable locking dynamics. Microwave quality and data performance are mostly preserved after conversion.", "author_names": [ "Kun-Lin Hsieh", "Yu-Han Hung", "Sheng-Kwang Hwang" ], "corpus_id": 39757388, "doc_id": "39757388", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Optical DSB to SSB conversion for radio over fiber links utilizing semiconductor lasers at stable locking dynamics", "venue": "2014 OptoElectronics and Communication Conference and Australian Conference on Optical Fibre Technology", "year": 2014 }, { "abstract": "Coherent optical frequency comb based on single section semiconductor quantum dots mode locked laser (QD MLL) is a promising device, which is able to provide a large number of equally spaced spectral lines simultaneously. We discuss the measurements and the spectral properties of QD MLL, including relative intensity noise, phase noise of each individual spectral line, as well as differential phase noise between spectral lines. More specifically, we report the frequency dependent nature of QD MLL phase noises, and its impact in the performance of coherent communication systems.", "author_names": [ "Rongqing Hui", "Mustafa Al-Qadi", "M O'sullivan", "Chongjin Xie" ], "corpus_id": 221912374, "doc_id": "221912374", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Spectral Properties of Quantum Dots Mode Locked Diode Lasers and the Impact in Fiber Optic Systems", "venue": "2020 22nd International Conference on Transparent Optical Networks (ICTON)", "year": 2020 }, { "abstract": "This paper presents a review and discussion of the directly modulated semiconductor lasers and their applications to optical communications and microwave photonics. A detailed and comprehensive demonstration of directly modulated semiconductor lasers from development history to specific techniques on measurement, analysis, and packaging is provided for the first time to the best of our knowledge. A few typical applications based on directly modulated lasers are also illustrated, such as optical fiber communications, free space optical communications and microwave photonics. Future directions of research are also highlighted.", "author_names": [ "Ninghua Zhu", "Zhan Shi", "Zhi ke Zhang", "Yi Zhang", "Canwen Zou", "Zeping Zhao", "Yu Liu", "Wei Li", "Ming Li" ], "corpus_id": 11325996, "doc_id": "11325996", "n_citations": 37, "n_key_citations": 1, "score": 0, "title": "Directly Modulated Semiconductor Lasers", "venue": "IEEE Journal of Selected Topics in Quantum Electronics", "year": 2018 }, { "abstract": "A novel scheme for all optical generate ultra wideband (UWB) pulse shape modulation (PSM) signals based on semiconductor fiber ring laser (SFRL) is proposed, in which three UWB PSM signals can be generated simultaneously. A comprehensive broad band dynamic model of this kind of all optical UWB PSM signals is presented and simulated. The numerical simulation results show that the central frequency (CF) of PSM signals, the 10dB bandwidth of PSM signals and the fractional bandwidth of PSM signals are 5GHz, 7GHz and 140% respectively, which satisfy the definition of the UWB.", "author_names": [ "Zan-shan Zhao" ], "corpus_id": 209457906, "doc_id": "209457906", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Research of all optical broadcast UWB pulse shape modulation signals based on semiconductor fiber ring laser", "venue": "2019 18th International Conference on Optical Communications and Networks (ICOCN)", "year": 2019 } ]

[ { "abstract": "Abstract I2CN 2K19:\"International Multi Conference on Computing, Communication, Electrical Nanotechnology\" aimed to bring together leading academic scientists, researchers and research scholars to exchange and share their experiences. It also provides the premier multidisciplinary forum for researchers, practitioners and educators to present and discuss the most recent innovations, trends, and concerns, practical challenges encountered and the solutions adopted in the field of Emerging Trends in Engineering and Technology.It covers the major areas like Advanced materials in Engineering, Bio Medical, Electronics and Green Architecture, Building Energy Conservation and Green Architecture,Computer Vision and Robotics, Computational Fluid Dynamics,Civil Engineering Materials,Chemical and Process Engineering,Design of Embedded system with VLSI, Data mining, Electrical Materials Electro magnetic, Electrical, Electronic and Systems Engineering, Green Manufacturing, Internal combustion Engines Internet and Mobile Computing, Instrumentation and Control Engineering, Mechatronics, MEMS and NEMS, Materials preparation and processing Nanotechnology, Nano Devices, New Technology, methods and Techniques in Civil Engineering, Networking, Communication and Multimedia, Photonics and Opto electronics, Power engineering, Pervasive, Grid, Cloud computing, Renewable and Non Renewable Energies, RADAR and satellite communication, Semiconductor devices, Structural.", "author_names": [ "T D Subash" ], "corpus_id": 219828945, "doc_id": "219828945", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Editorial Preface on the Proceedings of the International Multi Conference on Computing, Communication, Electrical and Nanotechnology, I2CN 2k19", "venue": "", "year": 2020 }, { "abstract": "Abstract ICMN 2K19:\"International Conference on Advances in Material Science and Nanotechnology\" aims to bring together leading academic scientists, researchers and research scholars to exchange and share their experiences. It also provides the premier multidisciplinary forum for researchers, practitioners and educators to present and discuss the most recent innovations, trends, and concerns, practical challenges encountered and the solutions adopted in the field of Emerging Trends in Engineering and Technology.It covers the major areas like Electrical Materials, MEMS and NEMS, Materials, preparation and processing Nanotechnology, Nano Devices, Semiconductor devices.", "author_names": [ "M Freeda" ], "corpus_id": 219812908, "doc_id": "219812908", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Editorial Preface on the Proceedings of the International Conference on Advances in Material Science and Nanotechnology, ICMN 2k19", "venue": "", "year": 2020 }, { "abstract": "Voila un article pour vous fan de catch americain. La WWE La wwe (world wrestling entertainment) est une entreprise ou federation de lutte professionnelle (catch) Le president de la compagnie.", "author_names": [ "Remy Tran" ], "corpus_id": 229090241, "doc_id": "229090241", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Catch:La World Wrestling Entertainment (wwe) College Jacques Daguerre Cormeilles en Parisis (95) College numerique", "venue": "", "year": 2020 }, { "abstract": "", "author_names": [ "K ManojP", "A SiyadM", "" ], "corpus_id": 228812646, "doc_id": "228812646", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Committees: International Conference on Energy and Environment 2019 (iCEE 2k19)", "venue": "", "year": 2020 }, { "abstract": "", "author_names": [ "K ManojP", "A SiyadM", "" ], "corpus_id": 228822647, "doc_id": "228822647", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Preface: International Conference on Energy and Environment 2019 (iCEE 2k19)", "venue": "", "year": 2020 }, { "abstract": "COVID 19, otherwise called coronavirus sickness 2019, is a respiratory disease brought about by extreme intense respiratory condition coronavirus 2 (SARS CoV 2) Fever is the most common symptom shown by Covid19 and other typical reactions consolidate hack, loss of yearning, depletion, curtness of breath, sputum creation, and muscle and joint pains. Transmission basically occurs through direct contact with infected person via mouth while speaking or coming in contact with spoiled surfaces. The First case of covid 19 was followed back to the city of wuhan, china, in late november 2019, which became serious in december. CoVs are encompassed, positive abandoned RNA infections with nucleocapsid. The agonizing time span for COVID 19 regions from 2 14 days, with a typical of 5 days, There is no particular antiviral treatment for COVID 19 as of now, and no antibody is right now accessible for which prevention becomes major role in reducing the spread. The BacilleCalmette Guerin (BCG) antibody, principally utilized for the counteraction of tuberculosis, is being assessed for the avoidance of COVID 1 and Clinical preliminaries are in progress to assess its proficiency against SARS CoV 2 and several pertinent studies and ongoing trials are in process.", "author_names": [ "Gaurav Kumar Sharma", "Kaushal Kishore Chandrul", "Roselin Khaklary" ], "corpus_id": 230650272, "doc_id": "230650272", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Review on Corona Virus 2K19 Pandemic", "venue": "", "year": 2020 }, { "abstract": "", "author_names": [ "Gao Xiong Shi Zheng Fu Jiao Tong Ju Zi Xun Shi Kai" ], "corpus_id": 226169183, "doc_id": "226169183", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "(Song Liao Wu Liao WWE huigiyua Elite Series Action 19 Daniel Bryan supotsu Action Figure toy [parallel import goods] Zheng Gui Shu Ru Pin :AU B01KPI974Q:mayumoStore", "venue": "", "year": 2020 }, { "abstract": "Major World Wrestling Entertainment storylines in the video streaming era problematize its historically central Real American hero figure. This article considers this shift against the concepts of", "author_names": [ "Wilson Koh" ], "corpus_id": 226323670, "doc_id": "226323670", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A Real American Hero: WWE Wrestling from American Exceptionalism to Commercial Transnationalism", "venue": "", "year": 2020 }, { "abstract": "Professional wrestling has long been of interest to cultural and media theorists (Barthes, 2015; Canella, 2016; Olson, 2018) Long before reality TV, the performativity and scripted drama of professional wrestling allowed theorists to unpack questions of fictionality and narrative authenticity. In the context of internet studies, professional wrestling raises additional questions: How do performers use social media to maintain relationships with fans? How do gender norms manifest in on stage versus online performances of professional identity? In this extended abstract, I present key concepts and guiding research questions for an investigation of fan culture and gender norms. I then provide a brief overview of related work and describe my mixed methods approach. As this research project is ongoing, I present preliminary findings and implications as a concluding section.", "author_names": [ "Jessa Lingel" ], "corpus_id": 225164139, "doc_id": "225164139", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "IN THE RING AND ONLINE: RELATIONAL LABOR AND AUDIENCE ENGAGEMENT IN THE WWE", "venue": "", "year": 2020 }, { "abstract": "", "author_names": [ "Gao Xiong Shi Zheng Fu Jiao Tong Ju Zi Xun Shi Kai" ], "corpus_id": 226160678, "doc_id": "226160678", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "(Song Liao Wu Liao WWE Super Strikers 6 Kofi huigiyua goods] Kingston Action Figure Super by Mattel [parallel import goods] Zheng Gui Shu Ru Pin :AU B01KPI8UGM:mayumoStore", "venue": "", "year": 2020 } ]

[ { "abstract": "A quantitative analysis of the excitonic luminescence efficiency in hexagonal boron nitride (h BN) is carried out by cathodoluminescence in the ultraviolet range and compared with zinc oxide and diamond single crystals. A high quantum yield value of ~50% is found for h BN at 10 K comparable to that of direct band gap semiconductors. This bright luminescence at 215 nm remains stable up to room temperature, evidencing the strongly bound character of excitons in bulk h BN. Ab initio calculations of the exciton dispersion confirm the indirect nature of the lowest energy exciton whose binding energy is found equal to 300+ 50 meV, in agreement with the thermal stability observed in luminescence. The direct exciton is found at a higher energy but very close to the indirect one, which solves the long debated Stokes shift in bulk h BN.", "author_names": [ "Leonard Schue", "Lorenzo Sponza", "Alexandre Plaud", "Hakima Bensalah", "Kenji Watanabe", "Takashi Taniguchi", "Francois Ducastelle", "Annick Loiseau", "J Barjon" ], "corpus_id": 73473466, "doc_id": "73473466", "n_citations": 38, "n_key_citations": 1, "score": 1, "title": "Bright Luminescence from Indirect and Strongly Bound Excitons in h BN.", "venue": "Physical review letters", "year": 2019 }, { "abstract": "Abstract Brittleness, relative high friction coefficient and wear rate limit the applications of ceramic coatings as wear resistant layers. However, because embedding additives with ceramic matrix has demonstrated to be an effective way to improve coating performances, different contents and size of h BN were added into an YSZ suspension. Afterwards, the YSZ/h BN composite coatings were manufactured by suspension plasma spray and their tribological analysis indicated that: i) the reduction of the friction coefficient and wear rate can be achieved by incorporating h BN into YSZ coating. ii) finer h BN particle is more helpful to enhance the tribological properties of the coating. iii) the optimum content is dependent on h BN particle sizes. iv) when the contents and the size of the h BN inclusion increase, the probability distribution of the micro hardness can become bi modal. Three worn surface conditions were summarized and their wear mechanisms were discussed as well.", "author_names": [ "Yongli Zhao", "Yan Wang", "Zexin Yu", "Marie-Pierre Planche", "Francois Peyraut", "Hanlin Liao", "Audrey Lasalle", "Alain Allimant", "Ghislain Montavon" ], "corpus_id": 139881895, "doc_id": "139881895", "n_citations": 18, "n_key_citations": 0, "score": 0, "title": "Microstructural, mechanical and tribological properties of suspension plasma sprayed YSZ/h BN composite coating", "venue": "", "year": 2018 }, { "abstract": "Abstract The growth of single layer graphene nanometer size domains by solid carbon source molecular beam epitaxy on hexagonal boron nitride (h BN) flakes is demonstrated. Formation of single layer graphene is clearly apparent in Raman spectra which display sharp optical phonon bands. Atomic force microscope images and Raman maps reveal that the graphene grown depends on the surface morphology of the h BN substrates. The growth is governed by the high mobility of the carbon atoms on the h BN surface, in a manner that is consistent with van der Waals epitaxy. The successful growth of graphene layers depends on the substrate temperature, but is independent of the incident flux of carbon atoms.", "author_names": [ "Jorge M Garcia", "Ulrich Wurstbauer", "Antonio Levy", "Loren N Pfeiffer", "Aron Pinczuk", "Annette S Plaut", "Lei Wang", "Cory R Dean", "Roberto Buizza", "Arend van der Zande", "James C Hone", "Kenji Watanabe", "Takashi Taniguchi" ], "corpus_id": 6651673, "doc_id": "6651673", "n_citations": 77, "n_key_citations": 1, "score": 0, "title": "Graphene growth on h BN by molecular beam epitaxy", "venue": "", "year": 2012 }, { "abstract": "Hexagonal boron nitride (h BN) and graphite are structurally similar but with very different properties. Their combination in graphene based devices is now of intense research focus, and it becomes particularly important to evaluate the role played by crystalline defects on their properties. In this paper, the cathodoluminescence (CL) properties of hexagonal boron nitride crystallites are reported and compared to those of nanosheets mechanically exfoliated from them. First, the link between the presence of structural defects and the recombination intensity of trapped excitons, the so called D series, is confirmed. Low defective h BN regions are further evidenced by CL spectral mapping (hyperspectral imaging) allowing us to observe new features in the near band edge region, tentatively attributed to phonon replicas of exciton recombinations. Second, the h BN thickness was reduced down to six atomic layers, using mechanical exfoliation, as evidenced by atomic force microscopy. Even at these low thicknesses, the luminescence remains intense and exciton recombination energies are not strongly modified with respect to the bulk, as expected from theoretical calculations, indicating extremely compact excitons in h BN.", "author_names": [ "Aur'elie Pierret", "Jorge Loayza", "Bruno Berini", "Andreas C Betz", "Bernard Placcais", "Franccois Ducastelle", "J Barjon", "Annick Loiseau" ], "corpus_id": 18724247, "doc_id": "18724247", "n_citations": 47, "n_key_citations": 0, "score": 0, "title": "Excitonic recombinations in h BN: From bulk to exfoliated layers", "venue": "", "year": 2014 }, { "abstract": "Abstract BN/metal sulfide composite (BN/In 2 S 3 was prepared by a facile in situ one pot hydrothermal method. The as synthesized photocatalyst was characterized by X ray powder diffraction (XRD) UV vis diffuse reflection spectroscopy (DRS) scanning electron microscopy (SEM) transmission electron microscopy (TEM) N 2 sorption analysis, electron spin resonance (ESR) photoluminescence emission spectra (PL) and X ray photoelectron spectroscopy (XPS) The results show that compared with single In 2 S 3 the BN/In 2 S 3 photocatalyst exhibits excellent photocatalytic performance for selective oxidation of aromatic alcohols to aromatic aldehydes under visible light irradiation. The enhanced photocatalytic activity of BN/In 2 S 3 composite is mainly attributed to the unique physicochemical properties of BN nanosheet, which acts as a promoter for photoexcited holes transfer, thereby improving the charge separation efficiency and prolonging photoexcited electrons lifetime. Effects of the type of aromatic alcohol and the added scavenger on the photocatalytic efficiency were also investigated. O 2 radicals and photogenerated holes play decisive roles for photocatalytic oxidation of aromatic alcohols to aromatic aldehydes. This approach is versatile for constructing other high efficiency photocatalysts such as BN/CdS, BN/Cd x Zn 1 x S and BN/ZnIn 2 S 4 It is hoped that this work could provide new insights to construct the BN based composites for extensive photocatalytic applications.", "author_names": [ "Sugang Meng", "Xiangju Ye", "Xiaofeng Ning", "Mengli Xie", "Xianliang Fu", "Shifu Chen" ], "corpus_id": 93569893, "doc_id": "93569893", "n_citations": 101, "n_key_citations": 1, "score": 0, "title": "Selective oxidation of aromatic alcohols to aromatic aldehydes by BN/metal sulfide with enhanced photocatalytic activity", "venue": "", "year": 2016 }, { "abstract": "Abstract Novel graphene like BN modified BiOBr materials have been synthesized via an ionic liquid assisted solvothermal process. The structure, morphology, optical and electronic properties were explored by the XRD, XPS, FT IR, SEM, TEM, DRS, PL, EIS and photocurrent. The photocatalytic performance of the graphene like BN/BiOBr materials was evaluated by the degradation of colorless antibiotic agent ciprofloxacin (CIP) tetracycline hydrochloride (TC) and rhodamine B (RhB) under visible light irradiation. When the mass fraction of graphene like BN is 1% the graphene like BN/BiOBr materials exhibited the highest activity. The enhanced light harvesting ability and higher separation efficiency of photogenerated electron hole pairs by the modification of graphene like BN contributed to the higher photocatalytic activity. The photo degradation is dominant by the O2 and hole oxidation process. This exploration of graphene like BN modified BiOBr open a window for the use of other graphene like BN based composites in photocatalysis field.", "author_names": [ "Jun Di", "Jiexiang Xia", "Mengxia Ji", "Bin Wang", "Sheng Yin", "Qi Zhang", "Zhigang Chen", "Huaming Li" ], "corpus_id": 94100821, "doc_id": "94100821", "n_citations": 222, "n_key_citations": 0, "score": 0, "title": "Advanced photocatalytic performance of graphene like BN modified BiOBr flower like materials for the removal of pollutants and mechanism insight", "venue": "", "year": 2016 }, { "abstract": "Abstract High active BN/CdS composite photocatalysts were prepared by the ball milling method. The prepared BN/CdS composites were characterized by the X ray powder diffraction (XRD) transmission electron microscopy (TEM) UV vis absorption spectra (UV vis) and fluorescence emission spectra (PL) The effects of the loading amounts of BN and the ball milling time on the H2 evolution rate were investigated. The results indicated that the tight contact of CdS with h BN can be achieved, and the photocatalytic activity of CdS could be improved substantially by coupling with a proper amount of milled h BN. The optimal loading amount of h BN was found to be 5 wt% and the milling time was 1 h. In the Pt/CdS/BN photocatalytic system, both the Pt as the electron acceptor and the BN as the hole transfer may cause the improvement of the CdS activity. The highest H2 evolution rate over the Pt/BN/CdS photocatalyst can reach as high as ~17.563 mmol g 1 h 1.", "author_names": [ "Ruizhen Zhang", "Jian Wang", "Peide Han" ], "corpus_id": 137195262, "doc_id": "137195262", "n_citations": 25, "n_key_citations": 0, "score": 0, "title": "Highly efficient photocatalysts of Pt/BN/CdS constructed by using the Pt as the electron acceptor and the BN as the holes transfer for H2 production", "venue": "", "year": 2015 }, { "abstract": "Abstract Graphene like BN/AgBr hybrid materials were synthesized using the facile water bath method and characterized using X ray diffraction (XRD) energy dispersive X ray spectrometry (EDS) transmission electron microscopy (TEM) X ray photoelectron spectroscopy (XPS) UV vis diffuse reflectance spectroscopy (DRS) photoluminescence (PL) Fourier transform infrared spectra (FT IR) inductively coupled plasma optical emission spectrometry (ICP OES) and Brunner Emmet Teller (BET) analysis. The photocatalytic activity of the graphene like BN/AgBr hybrid materials was evaluated using methyl orange (MO) as a target organic pollutant. The results indicated that the photocatalytic activity of AgBr could be significantly improved by coupling with a proper amount of graphene like BN. In addition, the optical loading amount of graphene like BN was observed to be 1 wt% The MO molecules can be decomposed completely within 15 min under visible light irradiation, and the photocatalyst can be reused 5 times without losing activity. The XRD pattern of the cycling sample revealed that no diffraction peaks of metallic Ag were present, which indicated that introducing a small amount of graphene like BN can effectively suppress the reduction of silver ions. The results of the photocurrent and impedance analysis indicated that a small amount of graphene like BN was beneficial for the separation of photogenerated electrons and holes, which could enhance the photoactivity of graphene like BN/AgBr. Based on the experimental results, a possible visible light photocatalytic degradation mechanism is also discussed.", "author_names": [ "Jiajia Chen", "Jiaxiang Zhu", "Zulin Da", "Hui Xu", "Jia Yan", "Haiyan Ji", "Huoming Shu", "Huaming Li" ], "corpus_id": 95154252, "doc_id": "95154252", "n_citations": 58, "n_key_citations": 1, "score": 0, "title": "Improving the photocatalytic activity and stability of graphene like BN/AgBr composites", "venue": "", "year": 2014 }, { "abstract": "Herein, novel graphene like BN/BiOBr composite was prepared through a facile solvothermal method in the presence of reactable ionic liquid [C16mim]Br. The structure and morphology of the as prepared samples were investigated by X ray diffraction (XRD) Transmission electron microscopy, field emission scanning electron microscope, energy dispersive X ray spectrometry, UV vis diffuse reflectance spectroscopy, Fourier transform infrared spectra and photoluminescence (PL) The photocatalytic activity was evaluated by the degradation of Rhodamine B (RhB) aqueous solution under visible light irradiation. Results showed that the 0.05 wt% BN/BiOBr composite catalysts exhibit higher photoactivity than pure BiOBr. The enhanced photocatalytic activity was attributed to the efficient separation of the photogenerated electron hole pairs of the composites which was confirmed by the electrochemical impedance spectroscopy, photocurrent and PL analysis. Meanwhile, the main active species of BN/BiOBr during the photocatalysis process were determined to be holes (h+", "author_names": [ "Bin Wang", "Jun Di", "Jiexiang Xia", "Li Xu", "Hui Xu", "Qi Zhang", "Zhigang Chen", "Huaming Li" ], "corpus_id": 138670776, "doc_id": "138670776", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Graphene like BN/BiOBr composite: synthesis via a reactable ionic liquid and enhanced visible light photocatalytic performance", "venue": "", "year": 2016 }, { "abstract": "Photoluminescence (PL) from femtosecond laser modified regions inside cubic boron nitride (c BN) was measured under UV and visible light excitation. Bright PL at the red spectral range was observed, with a typical excited state lifetime of ~4 ns. Sharp emission lines are consistent with PL of intrinsic vibronic defects linked to the nitrogen vacancy formation (via Frenkel pair) observed earlier in high energy electron irradiated and ion implanted c BN. These, formerly known as the radiation centers, RC1, RC2, and RC3, have been identified at the locus of the voids formed by a single femtosecond laser pulse. The method is promising to engineer color centers in c BN for photonic applications.", "author_names": [ "Ricardas Buividas", "Igal Aharonovich", "Gediminas Seniutinas", "Xue Wang", "Ludovic Rapp", "Andrei V Rode", "Takashi Taniguchi", "Saulius Juodkazis" ], "corpus_id": 14280931, "doc_id": "14280931", "n_citations": 19, "n_key_citations": 0, "score": 0, "title": "Photoluminescence from voids created by femtosecond laser pulses inside cubic BN.", "venue": "Optics letters", "year": 2015 } ]

[ { "abstract": "The electronic structure and optical spectrum of monolayer MoS2 are calculated using both the modified Becke Johnson (mBJ) approximation and Bethe Salpeter equation. Bulk MoS2 is an indirect band gap semiconductor, but thinned to a monolayer it converts to a direct band gap semiconductor with increased gap. The calculated mBJ band gaps of MoS2 amount to 1.15 eV for the bulk and 1.90 eV for the monolayer, in excellent agreement with experiment. The experimental excitonic peaks of monolayer MoS2 at 1.88 eV and 2.06 eV are reproduced by the calculations. The high photoluminescence yield can be attributed to a high binding energy of the excitons and is not due to a splitting of the valence bands, as is commonly assumed. We also show that monolayer MoS2 has the ability to oxidize H2O and produce O2 as well as to reduce H+ to H2.", "author_names": [ "N Singh", "Ghassan E Jabbour", "Udo Schwingenschlogl" ], "corpus_id": 121764607, "doc_id": "121764607", "n_citations": 96, "n_key_citations": 1, "score": 1, "title": "Optical and photocatalytic properties of two dimensional MoS2", "venue": "", "year": 2012 }, { "abstract": "Very recently, the two dimensional (2D) form of MoSi2N4 has been successfully fabricated [Hong et al. Sci. 369, 670 (2020) Motivated by theses recent experimental results, herein we investigate the structural, mechanical, thermal, electronic, optical and photocatalytic properties using hybrid density functional theory (HSE06 DFT) Phonon band dispersion calculations reveal the dynamical stability of MoSi2N4 monolayer structure. Furthermore, the mechanical study confirms the stability of MoSi2N4 monolayer. As compared to the corresponding value of graphene, we find the Youngs modulus decreases by 30% while the Poissons ratio increases by 30% In addition, its work function is very similar to that of phosphorene and MoS2 monolayers. The electronic structure investigation shows the MoSi2N4 monolayer is an indirect bandgap semiconductor. We have determined the bandgap using the HSE06 (GGA) is 2.35 (1.79) eV, which is an overestimated (underestimated) value of the experimental bandgap (1.99 eV) The thermoelectric study shows a good thermoelectric performance of the MoSi2N4 monolayer with a figure of merit slightly larger than unity at high temperatures. The optical analysis using the RPA method constructed over HSE06 shows that the first absorption peak of the MoSi2N4 monolayer for in plane polarization is located in the visible range of spectrum, i.e. it is a promising candidate for advancing optoelectronic nanodevices. The photocatalytic study indicates the MoSi2N4 monloayer can be a promising photocatalyst for water splitting as well as and CO2 reduction. In summary, the fascinating MoSi2N4 monloayer is a promising 2D material in many applications due to its unique physical properties.", "author_names": [ "Asadollah Bafekry", "M Faraji", "D M Hoat", "Mohamed M Fadlallah", "Masoud Shahrokhi", "Fazel Shojaei", "Daniela Gogova", "Mitra Ghergherehchi" ], "corpus_id": 221556965, "doc_id": "221556965", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "MoSi2N4 single layer: a novel two dimensional material with outstanding mechanical, thermal, electronic, optical, and photocatalytic properties", "venue": "", "year": 2020 }, { "abstract": "Abstract Van der Waals (vdW) heterostructure can improve the performance of the 2D materials and provide more applications. Based on density functional theory (DFT) calculations, the properties of vertical heterostructures formed by transition metal dichalcogenides (TMDs) MX2 (M Mo, W; X S, Se) and boron nitride (BP) were addressed. In particular, the vdW interaction exist in all these heterostructures instead of covalent bonding. The MoSe2/BP and WSe2/BP vdW heterostructures possess direct bandgap characterized by type II band alignment and powerful built in electric field across the interface, which can effectively separate the photogenerated charge. Meanwhile, the MoS2/BP and WS2/BP vdW heterostructures also have the direct bandgap and intrinsic type I band alignment. Furthermore, all heterostructures exhibit excellent optical absorption in the visible and near infrared regions. Our investigation shows an effective method to design new vdW heterostructures based on TMDs and explores their applications for photocatalytic, photovoltaic, and optical devices.", "author_names": [ "Kai Ren", "Minglei Sun", "Yi-dong Luo", "Sake Wang", "Jin Yu", "Wencheng Tang" ], "corpus_id": 139739289, "doc_id": "139739289", "n_citations": 75, "n_key_citations": 0, "score": 0, "title": "First principle study of electronic and optical properties of two dimensional materials based heterostructures based on transition metal dichalcogenides and boron phosphide", "venue": "Applied Surface Science", "year": 2019 }, { "abstract": "Abstract Four vertical heterostructures based on two dimensional transition metal dichalcogenides (TMDs) MoS2/GeC, MoSe2/GeC, WS2/GeC, and WSe2/GeC, were studied by density functional theory calculations to investigate their structure, electronic characteristics, principle of photogenerated electron hole separation, and optical absorption capability. The optimized heterostructures were formed by van der Waals (vdW) forces and without covalent bonding. Their most stable geometric configurations and band structures display type II band alignment, which allows them to spontaneously separate photogenerated electrons and holes. The charge difference and built in electric field across the interface of these vdW heterostructures also contribute to preventing the photogenerated electron hole recombination. Finally, the high optical absorption of the four TMD based vdW heterostructures in the visible and near infrared regions indicates their suitability for photocatalytic, photovoltaic, and optical devices.", "author_names": [ "Kai Ren", "Minglei Sun", "Yi-dong Luo", "Sake Wang", "Yujin Xu", "Jin Yu", "Wencheng Tang" ], "corpus_id": 128120509, "doc_id": "128120509", "n_citations": 29, "n_key_citations": 0, "score": 0, "title": "Electronic and optical properties of van der Waals vertical heterostructures based on two dimensional transition metal dichalcogenides: First principles calculations", "venue": "Physics Letters A", "year": 2019 }, { "abstract": "Two new two dimensional (2D) layered materials, namely, MgX2Se4 (X Al, Ga) monolayers, are predicted to possess novel electronic properties. Ab initio electronic structure calculations show that both MgAl2Se4 and MgGa2Se4 monolayers are direct gap semiconductors with bandgaps of 3.14 eV and 2.34 eV, respectively. The bandgap of both 2D materials is very sensitive to the in plane biaxial strain, while the strain induced bandgap changes allow the tuning of optical absorption from the violet to green light region. Also importantly, the in plane electron mobility of both 2D materials is predicted to be as high as ~0.7 1.0 x 103 cm2 V 1 s 1, notably higher than that of the MoS2 sheet ~200 cm2 V 1 s 1) while it is comparable to that of black phosphorene ~1000 cm2 V 1 s 1) suggesting their potential application in n type field effect transistors. Moreover, suitable bandgap and band edge alignment make the monolayer MgX2Se4 a potential photocatalyst for water splitting. Lastly, we show that MgX2Se4 possesses a lower monolayer cleavage energy than that of graphite, indicating easy exfoliation of MgX2Se4 layers from their bulk.", "author_names": [ "Pengfei Li", "Weiping Zhang", "Changhao Liang", "Xiao Cheng Zeng" ], "corpus_id": 204292572, "doc_id": "204292572", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Two dimensional MgX2Se4 (X Al, Ga) monolayers with tunable electronic properties for optoelectronic and photocatalytic applications.", "venue": "Nanoscale", "year": 2019 }, { "abstract": "Abstract Photocatalytic water splitting is one of the methods to produce hydrogen fuel by reducing the water into the oxygen and hydrogen provided that the bandgap of one catalyst is larger than +1.23 eV. In this paper, based on density functional theory, we investigated the structural, electronic and optical properties of heterostructure MoS2 (WS2) paired with GaN and we found out that MoS2/GaN/MoS2, WS2/GaN and WS2/GaN/WS2 vdW heterostructures are potential photocatalysts for photocatalytic applications. From the band structure and electronic partial density of states (PDOS) we confirm that all simulated heterostructures are direct semiconductors of type II band alignment with valence band maximum and conduction band minimum localized at pz orbital N atom of GaN and dz2 orbital Mo (or W) atom of MoS2 and WS2 respectively. The band offset induced by efficient interlayer charge transfer form a staggered gap which aids in exciton disassociation and charge separation. Our studied models are expected to harvest UV to visible light with absorption coefficient up to 3.38 x 10 5 cm 1 at wavelength of 102 nm. On top of that, our proposed heterosystem are also believed to be a promising device for various optoelectronic application specifically in from UV to near infrared with high performance.", "author_names": [ "Nur 'Adnin Akmar Zulkifli", "Suhana Binti Mohd Said", "Mohamad Fariz Mohamad Taib", "Khuzaimah Arifin", "Shaima Mohamad Ali Mahmood", "Kai Lin Woon", "Shobhit K Patel", "C L Tan", "Rozalina Binti Zakaria" ], "corpus_id": 222243832, "doc_id": "222243832", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Photocatalytic Application of Two dimensional Materials based Heterostructure Based on Molybdenum and Tungsten Disulfides and Gallium Nitride: A Density Functional Theory Study", "venue": "", "year": 2020 }, { "abstract": "Abstract Uniform two dimensional MoS2 nanoflakes were vertically assembled on the surface of reduced graphene oxide (MoS2/rGO composite film) via a hydrothermal process. The structure, morphology and optical properties of MoS2/rGO composite were studied. It is demonstrated that photocatalytic activity of the composite films for the degradation of methylene blue in the visible light range is much higher than that of isolated MoS2 and rGO. This is associated with an efficient transfer and a rapid separation of photogenerated electrons and holes at the heterojunction between MoS2 nanoflakes and rGO film.", "author_names": [ "Minfang Chen", "Carla Bittencourt", "Rony Snyders" ], "corpus_id": 104389909, "doc_id": "104389909", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Photocatalytic properties of MoS2 nanoflakes vertically assembled on reduced graphene oxide", "venue": "Thin Solid Films", "year": 2019 }, { "abstract": "Transition metal sulfide semiconductors have achieved significant attention in the field of photocatalysis and degradation of pollutants. MoS2 with a two dimensional (2D) layered structure, a narrow bandgap and the ability of getting excited while being exposed to visible light, has demonstrated great potential in visible light driven photocatalysts. However, it possesses fast paced recombination of charges. In this study, the coupled MoS2 nanosheets were synthesized with ZnO nanorods to develop the heterojunctions photocatalyst in order to obtain superior photoactivity. The charge transfer in this composite is not adequate to achieve desirable activity. Therefore, heterojunction was modified by reduced graphene oxide (RGO) nanosheets and carbon nanotubes (CNTs) to develop the RGO/ZnO/MoS2 and CNTs/ZnO/MoS2 ternary nanocomposites. The structure, morphology, composition, optical and photocatalytic properties of the as fabricated samples were characterized through X ray diffraction (XRD) Fourier Transform Infrared (FTIR) Field Emission Scanning Electron Microscopy (FESEM) Transmission Electron Microscopy (TEM) Energy Dispersive X ray (EDX) elemental mapping, Photoluminescence (PL) Ultraviolet Visible spectroscopy (UV VIS) and Brunauer Emmett Teller (BET) techniques. The photo catalytic performance of all samples was evaluated through photodegradation of aniline in aqueous solution. The combination of RGO or CNTs into the ZnO/MoS2 greatly promoted the catalytic activity. However, the resulting RGO/ZnO/MoS2 ternary nanocomposites showed appreciably increased catalytic performance, faster than that of CNTs/ZnO/MoS2. Charge carrier transfer studies, the BET surface area analysis, and the optical studies confirmed this superiority. The role of operational variables namely, solution pH, catalyst dosage amount, and initial concentration of aniline was then investigated for obtaining maximum degradation. Complete degradation was observed, in the case of pH 4, catalyst dosage of 0.7 g/L and aniline concentration of 80 ppm, and light intensity of 100 W. According to the results of trapping experiments, hydroxyl radical was found to be the main active species in the photocatalytic reaction. Meanwhile, a plausible mechanism was proposed for describing the degradation of aniline upon ternary composite. Moreover, the catalyst showed excellent reusability and stability after five consecutive cycles due to the synergistic effect between its components. Total Organic Carbon concentration (TOC) results suggested that complete mineralization of aniline occurred after 210 min of irradiation. Finally, a real petrochemical wastewater sample was evaluated for testing the catalytic ability of the as fabricated composites in real case studies and it was observed that the process successfully quenched 100% and 93% of Chemical Oxygen Demand (COD) and TOC in the wastewater, respectively.", "author_names": [ "Parisa Ghasemipour", "Moslem Fattahi", "Behnam Rasekh", "Fatemeh Yazdian" ], "corpus_id": 212641608, "doc_id": "212641608", "n_citations": 65, "n_key_citations": 0, "score": 0, "title": "Developing the Ternary ZnO Doped MoS2 Nanostructures Grafted on CNT and Reduced Graphene Oxide (RGO) for Photocatalytic Degradation of Aniline", "venue": "Scientific Reports", "year": 2020 }, { "abstract": "Abstract Owing to their unique physicochemical, optical and electrical properties, two dimensional (2D) MoS2 cocatalysts have been widely applied in designing and developing highly efficient composite photocatalysts for hydrogen generation under suitable light irradiation. In this review, we first elaborated on the fundamental aspects of 2D MoS2 cocatalysts to include the structural design principles, synthesis strategies, strengths and challenges. Subsequently, we thoroughly highlighted and discussed the modification strategies of 2D MoS2 H2 evolution cocatalysts, including doping heteroatoms (e.g. metals, non metals, and co doping) designing interfacial coupling morphologies, controlling the physical properties (e.g. thickness, size, structural defects or pores) exposing the reactive facets or edge sites, constructing cocatalyst heterojunctions, engineering the interfacial bonds and confinement effects. In the future, the forefront challenges in understanding and in precise controlling of the active sites at molecular level or atomic level should be carefully studied, while various potential mechanisms of photogenerated electrons interactions should be proposed. The applications of MoS2 cocatalyst in the overall water splitting are also expected. This review may offer new inspiration for designing and constructing novel and efficient MoS2 based composite photocatalysts for highly efficient photocatalytic hydrogen evolution.", "author_names": [ "Zizhan Liang", "Rongchen Shen", "Yun Hau Ng", "Peng Zhang", "Quanjun Xiang", "Xiao-ming Li" ], "corpus_id": 219473752, "doc_id": "219473752", "n_citations": 65, "n_key_citations": 0, "score": 0, "title": "A review on 2D MoS2 cocatalysts in photocatalytic H2 production", "venue": "", "year": 2020 }, { "abstract": "While two dimensional layered MoS2 nanosheets have been extensively studied owing to their fascinating optoelectronic properties, less attention has been paid on the corresponding zero dimensional nano crystals. In this contribution, we report the efficacy of MoS2 nanocrystals for their size tunable properties for optical and photocatalytic applications. We have synthesized different sized (10 70 nm) crystalline, hexagonal 2H MoS2 nanoparticles (NPs) dispersed in DMF solvent using a simple exfoliation technique. Synthesized NPs are found to exhibit size dependent optical properties and excitation dependent fluorescence characteristics in the visible region, which are not observed in bulk or 2D MoS2 layers. Size tunable band gap and broad absorbance and emission spectrum covering the visible range could be exploited in the fabrication of various opto electronic devices. Charge carrier emission dynamics of different sized MoS2 NPs are investigated using time correlated single photon counting (TCSPC) spectroscopic technique. We found two time components, one in the order of several hundreds of ps, which arises due to the radiative recombination of charge carriers, while the other one is of the order of a few ns, which emanates from the defect states of MoS2 NPs. The average time constants are found to decrease with increase in particle size. A noticeable photocatalytic activity of the synthesized MoS2 NPs under visible light illumination for the degradation of Brilliant Green dye is also demonstrated for the first time and the effect of size variation of NPs in the dye degradation process is reported.", "author_names": [ "D Bhattacharya", "Subhrajit Mukherjee", "Samit Kumar Ray", "Rajib Kumar Mitra" ], "corpus_id": 209358434, "doc_id": "209358434", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Size dependent optical properties of MoS2 nanoparticles and their photo catalytic applications.", "venue": "Nanotechnology", "year": 2019 } ]

[ { "abstract": "We have designed and developed an experimental setup to measure the Seebeck coefficient of a variety of samples at cryogenic temperatures and under magnetic fields up to 7 T employing the physical property measurement system (PPMS) The measurement technique uses a low frequency ac thermal gradient generated by two thin film heaters in thermal contact with the sample. Heaters and temperature sensors are all fitted on a standard PPMS sample puck. The validity of this method is tested by measuring the thermoelectric power of several superconductors and thermoelectric samples. We have used this technique to measure the thermoelectric power of various topological insulator single crystals (Pb0.8Sn0.2Te, Bi2Te3, Bi2Se2.1Te0.9, and Sb2Te3) The developed hardware and software control is suitable for studying the thermoelectric power of small samples (length 2 mm) in a commercial cryomagnetic system (PPMS) and it allows for studying superconductor, semiconductor, thermoelectric, or topological insulator material in wide temperature (2 300 K) and magnetic field (0 7 T) ranges.", "author_names": [ "Keshav Shrestha", "Melissa Gooch", "Bernd Lorenz", "Ching-Wu Chu" ], "corpus_id": 164608408, "doc_id": "164608408", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Experimental Setup of Ac Thermoelectric Power Measurements in a Cryocooler PPMS System and Its Implementation to Superconductors, Topological Insulator, and Thermoelectric Materials", "venue": "Instruments and Experimental Techniques", "year": 2019 }, { "abstract": "Abstract A long range magnetic order in the topological insulator (Bi2Te3) achieved a great interest by the doping of magnetic elements on to Bi and Te sites. The magnetic moments can be introduced by adding trivalent rare earth elements such as Ce and I. In this report, Bi2Te3, Ce0.2Bi1.8Te3, and Ce0.2Bi1.8Te2.9I0.1 nanoparticle were synthesized by the novel low temperature double solvent sol gel technique. The co doped nanoparticles were characterized by X ray diffraction (XRD) field emission scanning electron microscopy (FESEM) high resolution transmission electron microscopy (HRTEM) physical properties measurement system (PPMS) and vibrating sample measurement system (VSM) The VSM studies showed that the magnetization (M) of pure Bi2Te3 sample was successfully increased by adding iodine onto the Ce doped sample (Ce0.2Bi1.8Te2.9I0.1) For in depth analysis, PPMS results revealed that the as synthesized samples exhibit paramagnetic nature which then exchange into antiferromagnetic behavior after substituting Ce I onto Bi2Te3, at a varying temperature range from 0 to 400 K. The density functional theory (DFT) was also performed to understand the exchange biased phenomenon for as synthesized samples. Moreover, the experimental results can predict that the magnetic samples synthesized by the novel double solvent sol gel method can provide magnetic materials with large remnant magnetization compared with the pure Bi2Te3.", "author_names": [ "Syed Irfan", "Jingting Luo", "Fan Ping", "Zheng Zhuanghao" ], "corpus_id": 225138979, "doc_id": "225138979", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Theoretical and experimental investigation of magnetic properties of iodine and cerium Co doped Bi2Te3 nanoparticles", "venue": "", "year": 2020 }, { "abstract": "Abstract In this work we investigate the growth and magnetotransport properties of Co doped topological insulator Bi2Te3 deposited on Si(1 1 1) substrates by means of DC magnetron sputtering. The structure and morphology of the films were studied using X Ray Diffraction (XRD) Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) Magnetotransport measurements were performed with a Physical Property Measurement System (PPMS) The pristine samples have a metallic behavior while the Co doped are semiconductors. The magnetoresistance curves exhibit a sharp cusp for temperatures below 20 K that correspond to weak antilocalization phenomena and are analysed using the Hikami Larkin Nagaoka model. The WAL phenomenon vanishes with temperature increase due to electron phonon scattering. The doped samples present an ambipolar transport with a change in the sign of the dominant carriers with temperature.", "author_names": [ "A Pilidi", "Th Speliotis", "George Litsardakis" ], "corpus_id": 218960395, "doc_id": "218960395", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Structural and magnetotransport characterization of magnetron sputtered co doped Bi2Te3 thin films", "venue": "", "year": 2020 }, { "abstract": "Abstract We carried out a systematic study on the effect of the substitution of Ti2+ and Ru4+ ions for Fe3+ ions on the structural and magnetic properties of the strontium ferrite SrFe12 2xRuxTixO19 nanoparticles with 0 x 0.3 using x ray diffraction, Quantum Design PPMS 9 magnetometry, and electrical resistivity. A clear irreversibility between the zero field cooled and field cooled curves was observed below room temperature and the zero field cooled magnetization curves displayed a broad peak at a temperature TM. These results were discussed within the framework of random particle assembly model and associated with the magnetic domain wall motion. The resistivity data showed some kind of a transition from insulator to perfect insulator around T M The high temperature magnetization measurements exhibited sharp peaks just below Tc indicating a superparamagnetic behavior. With Ru Ti substitution, the saturation magnetization at 5 K showed small variations were it slightly increased with increasing x up to 0.2, and then decrease for x 0.3, while the coercivity decreased monotonically, recording a reduction of about 78% at x 0.3. These results were discussed in light of the cationic distributions based on the results of the structural refinements.", "author_names": [ "Abdel Khaleq Mousa Alsmadi", "Ibrahim Bsoul", "Sami H Mahmood", "G A Alna'washi", "Feras M O Al-Dweri", "Yazan Maswadeh", "Ulrich Welp" ], "corpus_id": 137005480, "doc_id": "137005480", "n_citations": 41, "n_key_citations": 0, "score": 0, "title": "Magnetic study of M type Ru Ti doped strontium hexaferrite nanocrystalline particles", "venue": "", "year": 2015 }, { "abstract": "We introduce the marriage of two technologies: digital microfluidics (DMF) a technique in which droplets are manipulated by application of electrostatic forces on an array of electrodes coated by an insulator, and porous polymer monoliths (PPMs) a class of materials that is popular for use for solid phase extraction and chromatography. In this work, circular PPM discs were formed in situ by dispensing and manipulating droplets of monomer solutions to designated spots on a DMF device followed by UV initiated polymerization. We used PPM discs formed in this manner to develop a digital microfluidic solid phase extraction (DMF SPE) method, in which PPM discs are activated and equilibrated, samples are loaded, PPM discs are washed, and the samples are eluted, all using microliter droplets of samples and reagents. The new method has extraction efficiency (93% comparable to that of pipet based ZipTips and is compatible with preparative sample extraction and recovery for on chip desalting, removal of surfactants, and preconcentration. We anticipate that DMF SPE may be useful for a wide range of applications requiring preparative sample cleanup and concentration.", "author_names": [ "Hao Yang", "Jared M Mudrik", "Mais J Jebrail", "Aaron R Wheeler" ], "corpus_id": 9719758, "doc_id": "9719758", "n_citations": 55, "n_key_citations": 1, "score": 0, "title": "A digital microfluidic method for in situ formation of porous polymer monoliths with application to solid phase extraction.", "venue": "Analytical chemistry", "year": 2011 }, { "abstract": "Surface plasmon polaritons (SPPs) are surface charge density oscillations localized to a metal dielectric interface. In addition to being considered as promising candidates for a variety of applications, structures that support SPPs, including metal insulator metal (MIM) multilayers, are of fundamental interest because of the variety of collective plasmonic modes they support. Previously, a particular class of \"forbidden\" plasmon polariton modes (PPMs) was proposed that includes plasmon polariton modes confined to a region of dispersion space not typically accessible to surface constructed collective excitations. Specifically, for these modes, known as Guided Wave PPMs (GW PPMs) due to the dielectric asymmetry of the central layer, the solution to the wave equation in the center insulator layer is oscillatory while remaining surface bound both to the supporting substrate and the exposed surface. These modes are supported by a simple physical structure that results from a minor symmetry modification of the traditional MIM structure, specifically the use of a central insulator layer with a higher refractive index than the supporting substrate. However, they display fundamental properties that are distinctly different from those of standard SPPs and from recently reported hybrid plasmonic modes. While GW PPMs have been explored theoretically, they have not yet been realized experimentally. In this article, we present the first experimental demonstration of GW PPMs. Specifically, we excite and detect GW PPMs at visible frequencies and match model predictions to experimental results with remarkable accuracy using minimal parameter fitting. In addition to the experimental detection, we calculate and report on other interesting and relevant features of the detected modes, including the associated electric field profiles, confinement values, and propagation lengths, and discuss in terms of the applications relevance of GW PPMs.Surface plasmon polaritons (SPPs) are surface charge density oscillations localized to a metal dielectric interface. In addition to being considered as promising candidates for a variety of applications, structures that support SPPs, including metal insulator metal (MIM) multilayers, are of fundamental interest because of the variety of collective plasmonic modes they support. Previously, a particular class of \"forbidden\" plasmon polariton modes (PPMs) was proposed that includes plasmon polariton modes confined to a region of dispersion space not typically accessible to surface constructed collective excitations. Specifically, for these modes, known as Guided Wave PPMs (GW PPMs) due to the dielectric asymmetry of the central layer, the solution to the wave equation in the center insulator layer is oscillatory while remaining surface bound both to the supporting substrate and the exposed surface. These mode.", "author_names": [ "Rachel C Owen", "Kodiak S Murphy", "Kyle Hoke", "Trevor James Morgan", "Brad L Johnson", "Janelle M Leger" ], "corpus_id": 125502303, "doc_id": "125502303", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Detection of guided wave plasmon polariton modes in a high index dielectric MIM structure", "venue": "", "year": 2017 }, { "abstract": "The processing, microstructures and properties of La0.7Sr0.3Mn1 xZnxO3 perovskite manganite, with x=0, 0.1, 0.2, and 0.3 have been investigated. X ray diffraction, scanning electron microscopy (SEM) and other characterisation methods were used to study the relations of microstructure and properties. The X ray powder diffraction results show a single phase for the 0<<em>x<0.3 region that confirms the zinc incorporation into the Mn site. The SEM images with magnification 1500x indicate that the studied system is a single phase. The transport measurements show decreasing of insulator to metal transition temperature, Tt, with increasing the zinc concentration on the Mn site, while the resistivity increases with increasing the zinc doping level for 0<<em>x<0.1. The maximum resistivities are found at 380 and 160 K, respectively. The PPMS measurements show that the magnetisation value is greatest for x=0.1 and drastically decrease for the parent material, as well as with increasing the zinc doping concentration above 20% when the compound changes from ferromagnetic to paramagnetic. The paramagnetic to ferromagnetic transition temperature variations, Tc, agrees with the insulator to metal variations, Tt, from the transport measurements for the parent and 10% doped material. For zinc doping levels above 20% the behavior of the studied system changes from ferromagnetic to paramagnetic.", "author_names": [ "Emilia Velinova Sotirova-Haralambeva", "Xio Lin Wang", "K H Liu", "T M Silver", "Konstantin Konstantinov", "Joseph Horvat" ], "corpus_id": 35431198, "doc_id": "35431198", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Zinc doping effects on the structure transport and magnetic properties of La 0 7 Sr 0 3 Mn 1 2 x Zn x O 3 manganite oxide", "venue": "", "year": 2017 }, { "abstract": "The positron annihilation techniques and X ray diffraction have been used to study the microstructure of the La0.67Ca0.33MnO3 ceramics prepared by the solid state reaction method at different sintered temperatures (T=1573K, 1623K, 1673K, 1723K, 1773K, 1823K) And the electro magnetic transport behavior of the samples was measured by VSM and Resistivity modular on PPMS. According to these results, all samples show a perovskite structure, the ferromagnetic paramagnetic and metal insulator transitions occur at the transition temperature Tc and TMI, respectively, which is almost the same. For La0.67Ca0.33MnO3 sintered at 1673K, the mean positron lifetime is the largest, the maximum value of the magnetization is achieved on the magnetization temperature curve at H=0.2mT, while the transition temperature occurs at about 244K.", "author_names": [ "Shoulei Xu", "Er Juan Xie", "Xiu Cao", "Yu Yang Huang", "Dingkang Xiong", "Wen Deng" ], "corpus_id": 136328910, "doc_id": "136328910", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Studies of Microstructure and Electro Magnetic Transport Property of La0.67Ca0.33MnO3 Ceramic", "venue": "", "year": 2017 }, { "abstract": "We have successfully measured physical and magnetic properties of the La0.5Ca0.5Mn0.9Cu0.1O3 at temperature in the range of 10 100 K. Physical properties have covered electrical resistivity and specific heat. The properties, which serve as a function of temperature, were investigated by using Physics Properties Measurement System (PPMS) with and without an external magnetic field up to 8.5 Tesla. The magnetic structure was characterized using High Resolution Powder Diffraction (HRPD) at room and low temperatures. Furthermore, the magnetization was measured by using Magnetic Properties Measurement System (MPMS) with the external magnetic field of 0 7 Tesla. In the temperature interval of 10 53 K, the resistivity of the sample increased with the increasing of external magnetic field. At temperatures T 53 K, the samples were crystalline metal. This was revealed by fitting the graph Ln R as a function of 1/T. At temperatures T 53 K, the sample was an insulator according to fittings Ln R as a function of 1/T 0.25 The result was also shown by the decreasing value of the resistivity of the sample. The transition temperature of the metal insulator (TMI) decreased with the increasing of external magnetic field, i.e. from 60 K without an external magnetic field to 53 K with external magnetic field 8.5 Tesla. A coefficient electron specific heat and specific heat of spin wave increased, and phonon specific heat was relatively unchanged in the presence of an external magnetic field. Results of HRPD experiment were analyzed by using Fullprof program. At room temperature, the sample had the paramagnetic phase, while at low temperatures of 20 K it had antiferromagnetic phase. Temperature phase transition from the paramagnetic to antiferromagnetic phase or Neel temperature was around 225 K. However, the saturation magnetization of the sample was not observed.", "author_names": [ "Yohanes Edi Gunanto", "Wisnu Ari Adi", "Eden Steven", "Budhy Kurniawan", "Takayuki Ono", "H K Tanaka" ], "corpus_id": 4673712, "doc_id": "4673712", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Physical and Magnetic Properties of La 0 5 Ca 0 5 Mn 0 9 Cu 0 1 O 3 at Temperature in the Range of 10 100", "venue": "", "year": 2017 }, { "abstract": "An inorganically template metaphosphoric acid containing copper salt, nanomaterial, has been synthesized and characterized with different measurement techniques such as Differential Scanning Calorimeter (DSC) UV Vis NIR, HRTEM, VSM, PPMS and X RD. The thermal property of this salt has been studied at a low temperature up to 223 K from 298 K with DSC. The specific heat capacity of this complex has been measured in atmospheric O2 at a rate of 10 K min 1 from 298 K to 223 K and vice versa in two thermal cycles. The net specific heat capacity of this salt is found 88.28 J/gm.K and 86.56 J/gm.K in first and second thermal cycles, respectively. There is a discontinuity in the specific heat at 106 s while measuring the specific heat capacity of the above nanomaterial at constant temperature 283 K. This particle size of this nanomaterial is 10 nm. The paramagnetic Curie temperature (thP) and Curie constant (C) are 18.29 K and 1.35x10 3 respectively. This material founds insulator from PPMS and UV Vis NIR mea.", "author_names": [ "Trilochan Swain", "Gouri Sankhar Brahma" ], "corpus_id": 63599472, "doc_id": "63599472", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Low temperature property of Metaphosphatecopper(II/I) salt", "venue": "", "year": 2016 } ]

[ { "abstract": "Abstract Large single crystals of the semiconductor MnIn 2 Se 4 have been grown by the chemical vapour phase transport technique using AlCl 3 as transport agent. The plate like crystals had a size of up to 1 cm 2 Thermodynamic considerations revealed that Mn Al Cl complexes are important for the chemical vapour transport. It was found that MnIn 2 Se 4 has a rhombohedral unit cell belonging to the space group R3m with the lattice parameters of a 4.05(6) A and c 39.4(9) A at 300 K. The thermal expansion coefficients were investigated between 80 and 300 K. According to the crystal structure of ZnIn 2 S 4 a crystal structure model of MnIn 2 Se 4 was proposed, but the distribution of the cations Mn and In in the unit cell could not be completely determined.", "author_names": [ "Gerhard Doll", "Martha Ch Lux-Steiner", "Christian Kloc", "Judith R Baumann", "Ernst Bucher" ], "corpus_id": 94647609, "doc_id": "94647609", "n_citations": 19, "n_key_citations": 0, "score": 1, "title": "Chemical vapour transport and structural characterization of layered MnIn2Se4 single crystals", "venue": "", "year": 1990 }, { "abstract": "Chemical and structural characterization has been performed for thick (100 600 mm) and thin (10 100 mm) 2H/4H inter polytype SnS2 crystals grown by low temperature chemical vapour transport in the reverse temperature gradient geometry. X ray diffraction shows that the 2H/4H SnS2 phase transforms to single crystal 2H SnS2 in 6 12 months. The S/Sn ratio is 2.02+ 0.01 in thick crystals and 2.01+ 0.01 in thin crystals. Thermogravimetric/differential thermal analysis and the other characterization techniques show no difference between the two types of crystal. Extremely small quantities of carbon and oxygen and some chlorine were detected by secondary ion mass spectroscopy and/or X ray photoelectron spectroscopy (XPS) These elements are concentrated at the surface. The XPS data show a chemical shift of tin and sulphur in the surface layer, which is probably caused by the adsorbed carbon and oxygen; however, it cannot be explained by the formation of the usual oxides of tin and sulphur.", "author_names": [ "Takashi Shibata", "Yoshihisa Muranushi", "Tomoyuki Miura", "Tomiya Kishi" ], "corpus_id": 135727833, "doc_id": "135727833", "n_citations": 9, "n_key_citations": 0, "score": 1, "title": "Chemical and structural characterization of SnS2 single crystals grown by low temperature chemical vapour transport", "venue": "Journal of Materials Science", "year": 1991 }, { "abstract": "Abstract In the present study, the single crystals of WSe1.93 were grown by chemical vapour transport (CVT) technique. Iodine was used as transporting agent. The purity and stoichiometry of the as grown WSe1.93 single crystals were determined by energy dispersive analysis of X ray (EDAX) The structural characterization was done by X ray diffraction (XRD) technique. The scanning electron microscopy (SEM) of the as grown single crystal surfaces showed that the crystal growth took place by layer growth mechanism. The thermogravimetric (TG) differential thermogravimetric (DTG) and differential thermal analysis (DTA) of as grown WSe1.93 single crystal in inert N2 atmosphere showed two stages decomposition. The thermal parameters like activation energy (Ea) Arrhenius constant (A) enthalpy change (DH) the entropy change (DS) and the free energy change (Gibbs function) (DG) were calculated using Kissinger method. The optical bandgaps were determined from the optical absorption spectrum. The d.c. electrical resistivity measurements in the temperature range of 303 483 K showed that the resistivity value decreases with increase of temperature, in line with semiconducting behavior. The p type semiconducting nature of the sample was confirmed by Hall effect and thermoelectric power (TEP) measurements. The obtained results are discussed in details.", "author_names": [ "Jiten P Tailor", "Devangini S Trivedi", "S H Chaki", "Mahesh D Chaudhary", "Milind P Deshpande" ], "corpus_id": 100186771, "doc_id": "100186771", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Study of chemical vapour transport (CVT) grown WSe1.93 single crystals", "venue": "", "year": 2017 }, { "abstract": "Single crystals of niobium sulphide (NbS2) having a layered structure were grown by chemical vapour transport technique (CVT) using iodine as transporting agent. The stoichiometry of the grown crystals was confirmed on the basis of energy dispersive analysis by X ray (EDAX) and the structural characterization was accomplished by Xray diffraction (XRD) studies. The crystals were found to possess hexagonal crystal structure. The lattice parameters, volume, particle size and X ray density was carried out for this crystal. The grown crystals were examined under optical zoom microscope for their surface topography study. Hall Effect measurements were carried out on grown crystals at room temperature. The positive value of Hall coefficient implies that this crystal is p type in nature. The results obtained are discussed in detail.", "author_names": [ "Mehul Dave", "Kaushik Patel", "Rajiv Vaidya" ], "corpus_id": 209359545, "doc_id": "209359545", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "STRUCTURAL CHARACTERIZATIONS OF NBS2 SINGLE CRYSTALS", "venue": "", "year": 2012 }, { "abstract": "Abstract Single crystals of layer compounds with composition MoS x Se 2 x where x varies within the range 0 to 2, have been grown by the direct vapour transport technique to the maximum size of 15 mm x 10 mm x 0.3 mm. The series forms a complete range of isomorphous solid solutions, showing good agreement with Vegard's law. The composition of the above crystals was examined by ESCA (Electron Spectroscopy for Chemical Analysis) Crystal lattice parameters have been determined for the series with an X ray diffractometer.", "author_names": [ "M K Agarwal", "Lakhichand Tulshiram Talele" ], "corpus_id": 96527539, "doc_id": "96527539", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Growth conditions and structural characterization of molybdenum sulphoselenide single crystals: (MoSxSe2 x, 0<=x<=2)", "venue": "", "year": 1985 }, { "abstract": "This paper represents the investigation on growth of single crystals of GeTe0.1Se0.9 using Chemical Vapour Transport (CVT) technique using Iodine as a transporting agent. Photographs of Energy Dispersive Analysis of Xray (EDAX) reveals that GeTe0.1Se0.9 single crystals are nearly stoichiometrically perfect. Structural confirmation of these crystals was accomplished by Xray diffraction and it shows that GeTe0.1Se0.9 has hexagonal closed packed crystal structure and lattice parameters have been calculated. The electron diffraction pattern/photograph confirms the single crystallinity of the grown crystal. A study of microstructures on this crystal has been made and its layered pattern is found. The characterization of optical band gap has been calculated at room temperature throughout the wavelength 200 2500 nm near the fundamental absorption edge. It shows that grown crystals have direct and indirect energy gaps of 1.08 eV and 0.8 eV respectively.", "author_names": [ "G K SOLANKIa", "Dipika B PATELa", "Sandip UNADKATb", "N N GOSAIa", "Ruchita R PATELa" ], "corpus_id": 203558065, "doc_id": "203558065", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "SYNTHESIS OF GeTe 0 1 Se 0 9 SINGLE CRYSTALS AND ITS STRUCTURAL AND OPTICAL CHARACTERIZATION", "venue": "", "year": 2010 }, { "abstract": "This paper represents the investigation on growth of single crystals of GeTe0.1Se0.9 using Chemical Vapour Transport (CVT) technique using Iodine as a transporting agent. Photographs of Energy Dispersive Analysis of X ray (EDAX) reveals that GeTe0.1Se0.9 single crystals are nearly stoichiometrically perfect. Structural confirmation of these crystals was accomplished by X ray diffraction and it shows that GeTe0.1Se0.9 has hexagonal closed packed crystal structure and lattice parameters have been calculated. The electron diffraction pattern/photograph confirms the single crystallinity of the grown crystal. A study of microstructures on this crystal has been made and its layered pattern is found. The characterization of optical band gap has been calculated at room temperature throughout the wavelength 200 2500 nm near the fundamental absorption edge. It shows that grown crystals have direct and indirect energy gaps of 1.08 eV and 0.8 eV respectively.", "author_names": [ "G K Solanki", "Dipika B Patel", "Sandip Unadkat", "Nitingiri N Gosai", "Ruchita R Patel" ], "corpus_id": 137953210, "doc_id": "137953210", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "SYNTHESIS OF GeTe0.1Se0.9 SINGLE CRYSTALS AND ITS STRUCTURAL AND OPTICAL CHARACTERIZATION", "venue": "", "year": 2010 }, { "abstract": "Single crystals of niobium sulphide (NbS 2 having a layered structure were grown by chemical vapour transport technique (CVT) using iodine as transporting agent. The chemical composition of as grown crystals have been confirmed on the basis of energy dispersive analysis by X ray. The structural analysis of as grown crystals have been accomplished by X ray diffraction (XRD) analysis. The lattice parameters obtained from the XRD analysis were a 3.33 A c =17.86 A. The X ray density was found to be 3.03 gm/cc and volume was calculated about 171.8 A 3 .This crystal is found to possess hexagonal, layered structure. The resistivity measurements of the grown crystals were carried out within the temperature range of temperature 300 K to 423 K. The crystals were found to exhibit semiconducting nature in this temperature range. The behavior of the resistance under pressure is thoroughly studied using Bridgman anvil set up upto 8 GPa. The nature of resistance found to be decreases with increasing pressure which indicate also semiconducting nature.", "author_names": [ "Mehul Dave", "Kaushik Patel", "Rajiv Vaidya" ], "corpus_id": 99326216, "doc_id": "99326216", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Growth, characterizations and highpressure studies of niobium sulphide single crystals", "venue": "", "year": 2016 }, { "abstract": "Transition metal trichalcogenides are well suited for extreme pressure lubrication. These materials being semiconducting and of layered structure may undergo structural and electronic transition under pressure. In this paper authors reported the details about synthesis and characterization of zirconium sulphoselenide single crystals. The chemical vapour transport technique was used for the growth of zirconium sulphoselenide single crystals. The energy dispersive analysis by X ray (EDAX) gave the confirmation about the stoichiometry of the as grown crystals and other structural characterizations were accomplished by X ray diffraction (XRD) study. The variation of electrical resistance was monitored in a Bridgman opposed anvil set up up to 8 GPa pressure to identify the occurrence of any structural transition. These crystals do not possess any structural transitions upto the pressure limit examined.", "author_names": [ "Kaushik Patel", "Rajiv Vaidya", "Mehul Dave", "S G Patel" ], "corpus_id": 122247119, "doc_id": "122247119", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Growth and high pressure studies of zirconium sulphoselenide single crystals", "venue": "", "year": 2009 }, { "abstract": "The zirconium triselenide (ZrSe 3 single crystal has been grown by chemical vapour transport technique using iodine as a transporting agent. The optimum condition for the growth of this crystal is given. The stoichiometry of the grown crystals was confirmed on the basis of energy disperse analysis by X ray (EDAX) and remaining structural characterization was accomplished by X ray diffraction (XRD) studies. The lattice parameters obtained from the XRD analysis were a= 5.45 A, b=3.74 A and c=9.44 A. This crystal is found to possess monoclinic, layered structure. The X ray density was found to be 5.63 g/cc and volume was calculated about 193.50 A3. The optical band gap of the as grown crystal has been carried out with the help of optical absorption spectra in the range 700 1400 nm.", "author_names": [ "Kaushik Patel", "Rajiv Vaidya", "S G Patel" ], "corpus_id": 67783579, "doc_id": "67783579", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Microstructural analysis of zirconium triselenide single crystals", "venue": "", "year": 2007 } ]

[ { "abstract": "A thriving semiconductor industry has been created in Taiwan over the course of the past two decades by the use of advanced organizational techniques of technology leverage and accelerated technology diffusion. By the mid 1990s, the industry had reached a level of output that placed it behind only the U.S. Japan, and Korea. Almost all of Taiwan's semiconductor industry is located in the Hsinchu Science Based Industry Park, which was created in emulation of California's Stanford Research Park, but with more direct government involvement. This article explores the extent to which this emergent Silicon Valley in Taiwan shares the \"industrial ecology\" that has powered innovation in California and examines the extent to which the Taiwan industry suffers from weaknesses attributable to its rapid creation through technology leverage.", "author_names": [ "John A Mathews" ], "corpus_id": 154417261, "doc_id": "154417261", "n_citations": 226, "n_key_citations": 20, "score": 1, "title": "A Silicon Valley of the East: Creating Taiwan's Semiconductor Industry", "venue": "", "year": 1997 }, { "abstract": "List of Tables and Figures Preface Introduction: The State also Rises: The Roots of Contemporary State Activism Jonah Levy I. VARIETIES OF STATISM 1. The Transformation of the British State: From Club Government to State Administered High Modernism Michael Moran 2. The Forgotten Center: State Activism and Corporatist Adjustment in Holland and Germany Anton Hemerijck and Mark Vail 3. Exiting Etatisme? New Directions in State Policy in France and Japan Jonah Levy, Mari Miura, and Gene Park II. THE STATE AND SOCIAL GROUPS 4. The State and the Reconstruction of Industrial Relations Institutions after Fordism: Britain and France Compared Chris Howell 5. Building Finance Capitalism: The Regulatory Politics of Corporate Governance Reform in the United States and Germany John Cioffi 6. From Maternalism to \"Employment for All\" State Policies to Promote Women's Employment across the Affluent Democracies Ann Shola Orloff III. THE MARKET MAKING STATE 7. The State in the Digital Economy John Zysman and Abraham Newman 8. Building Global Service Markets: Economic Structure and State Capacity Peter Cowhey and John Richards 9. The Transformation of European Trading States Richard Steinberg Conclusion: The State after Statism: From Market Direction to Market Support Jonah Levy Notes References Contributors Index", "author_names": [ "Jonah David Levy" ], "corpus_id": 142004143, "doc_id": "142004143", "n_citations": 140, "n_key_citations": 7, "score": 0, "title": "The state after statism new state activities in the age of liberalization", "venue": "", "year": 2006 }, { "abstract": "An acidophilic, slightly thermophilic bacterium, designated strain NTAP 1T, that produces a thermostable extracellular acid collagenase activity with potential industrial applications was isolated from soil of Aoba yama Park, Sendai, Japan. The temperature range for growth was 40 65 degrees C, with an optimum at 55 degrees C, and the pH range for growth was 2.5 6.5, with an optimum at pH 5.5. Analysis of the 16S rDNA sequence of strain NTAP 1T showed that it is most closely related to strains of the genus Alicyclobacillus. Consistently, the major constituents of the cell membrane lipid of strain NTAP 1T were omega alicyclic fatty acids. However, DNA DNA reassociation studies showed only low similarities (less than 33% to any type strain of Alicyclobacillus. On the basis of the phenotypic and genotypic properties, a novel species is proposed, Alicyclobacillus sendaiensis sp. nov. represented by strain NTAP 1T =JCM 11817T=ATCC BAA 609T)", "author_names": [ "Naoki Tsuruoka", "Yuri Isono", "Osamu Shida", "Hisashi Hemmi", "Toru Nakayama", "Tokuzo Sendai-shi Nishino" ], "corpus_id": 12900086, "doc_id": "12900086", "n_citations": 59, "n_key_citations": 6, "score": 0, "title": "Alicyclobacillus sendaiensis sp. nov. a novel acidophilic, slightly thermophilic species isolated from soil in Sendai, Japan.", "venue": "International journal of systematic and evolutionary microbiology", "year": 2003 }, { "abstract": "An Introduction to International and Comparative Employment Relations Greg J Bamber and Russell D Lansbury Employment Relations in Britain John Goodman et al Employment Relations in the United States Hoyt N Wheeler and John A McLendon Employment Relations in Canada Mark Thompson Employment Relations in Australia Edward M Davis and Russell D Lansbury Employment Relations in Italy Claudio Pellegrini Employment Relations in France Janine Goetschy and Annette Jobert Employment Relations in Germany Friedrich Furstenberg Employment Relations in Sweden Olle Hammarstrom and Tommy Nilsson Employment Relations in Japan Yasuo Kuwahara Employment Economics and Industrial Relations Young bum Park and Chris Leggett Conclusions: Towards a Synthesis of International and Comparative Experience in Employment Relations Oliver Clarke, Greg J Bamber and Russell D Lansbury Employment, Economics and Industrial Relations Peter Ross and Gillian Whitehouse Comparative Statistics", "author_names": [ "Greg J Bamber", "Russell D Lansbury" ], "corpus_id": 142606528, "doc_id": "142606528", "n_citations": 40, "n_key_citations": 5, "score": 0, "title": "International and comparative employment relations a study of industrialised market economies", "venue": "", "year": 1998 }, { "abstract": "Via a large scale cross sectional study among Japanese white color workers, the authors aimed to elucidate: (1) the distributions of Sense of Coherence (SOC) which reflect stress coping abilities, (2) the distributions of the Brief Scale for Coping Profile (BSCP) which reflect coping profiles for stressors; (3) and the association between SOC and BSCP. Anonymous self administered questionnaires were sent to 20,742 employees at educational and research institutions in Tsukuba Research Park City. A total of 12,009 (57.9% workers completed and returned the questionnaire; 10,317 workers without missing data were analyzed. SOC scale scores and BSCP subscale scores differed by gender, age, and other demographic features. Among the BSCP subscales, workers whose SOC scale scores were higher tended to adopt a problem focused coping profile, whereas workers whose SOC scale scores were lower adopted an emotion focused coping profile. The coping profile that workers adopted depended on their background and demographic characteristics. Stronger SOC allowed one to adopt a problem focused coping profile that allows for better coping with work related stressors.", "author_names": [ "Yusuke Tomotsune", "Shinichiro Sasahara", "Tadahiro Umeda", "Mikiko Hayashi", "Kazuya Usami", "Satoshi Yoshino", "Takayuki Kageyama", "Hiroyuki Nakamura", "Ichiyo Matsuzaki" ], "corpus_id": 30668769, "doc_id": "30668769", "n_citations": 25, "n_key_citations": 3, "score": 0, "title": "The association of sense of coherence and coping profile with stress among research park city workers in Japan.", "venue": "Industrial health", "year": 2009 }, { "abstract": "Can clusters be made to order? By Shahid Yusuf. Lessons from the development of silicon valley and its entrepreneurial support network for Japan by Martin Kenney. The emergence of Hsinchu science park as an IT cluster by Tain Jy Chen. Coping with globalization of production networks and digital convergence: the challenge of ICT cluster development in Singapore by Poh Kam Wong. Bangalore cluster: evolution, growth, and challenges by Rakesh Basant. ICT clusters and industrial restructuring in the Republic of Korea: the case of Seoul by Sam Ock Park. Constructing jurisdictional advantage in a mature economy: the case of Kitakyushu, Japan by Maryann P. Feldman. Kitakyushu: desperately seeking clusters by Kaoru Nabeshima and Shoichi Yamashita.", "author_names": [ "Shahid Yusuf", "Kaoru Nabeshima", "Shoichi Yamashita", "Martin Kenney", "Tain-Jy n Che", "Poh Kam Wong", "Rakesh Basant", "Sam Ock Park", "Maryann Feldman" ], "corpus_id": 153147429, "doc_id": "153147429", "n_citations": 53, "n_key_citations": 2, "score": 0, "title": "Growing Industrial Clusters in Asia: Serendipity and Science", "venue": "", "year": 2008 }, { "abstract": "Abstract Ant fauna of a green buffer belt adjacent to an industrial zone in Kagoshima City, southern Kyushu, Japan was elucidated using a standardized protocol. A total of 39 species belonging to 24 genera in five subfamilies were recorded from this park. Most speciose genera are Camponotus and Tetramorium having four species. The number of species per genus is 1.56 on average. Pheidole noda F. Smith, Monomo rium chinense Santschi, Solenopsis japonica Wheeler, Tetramorium bicarinatwn (Nylander) and Technomyrmex albipes (F. Smith) were most frequently encountered. Excepting Pheidole noda they are open land and/or forest edge inhabitants. Furthermore, Tetramorium bica rinatum and Technomyrmex albipes are tramp species. Thus, ant fauna there strongly reflects environmental conditions derived from urbanization/industrialization. Based on the present results, we propose here a new protocol monitoring ants in urban/industrial zones consisting of baiting and time unit sampling.", "author_names": [ "K Iwata", "Katsuyuki Eguchi", "Seiki Yamane" ], "corpus_id": 85434770, "doc_id": "85434770", "n_citations": 11, "n_key_citations": 2, "score": 0, "title": "A Case Study on Urban Ant Fauna of Southern Kyusyu, Japan, with Notes on a New Monitoring Protocol (Insecta, Hymenoptera, Formicidae)", "venue": "", "year": 2005 }, { "abstract": "Ministry of Education, Culture and Science of Japan, Hiroshima Industrial Technology Organization, KOSEF (Korea Science and Engineering Foundation)", "author_names": [ "Yun Chan Kang", "Seung-Bin Park", "I Wuled Lenggoro", "Kikuo Okuyama" ], "corpus_id": 55052866, "doc_id": "55052866", "n_citations": 79, "n_key_citations": 2, "score": 0, "title": "Preparation of nonaggregated Y2O3 Eu phosphor particles by spray pyrolysis method", "venue": "", "year": 1999 }, { "abstract": "In view of the unprecedented devastation of the Great East Japan Earthquake (GEJE) the psychological overreaction tends to emphasize the safety aspects at the expense of the basic principle of designing industrial supply chains that achieve competitiveness and robustness simultaneously. Manufacturing firms must identify the \"weak links\" in their supply chains in terms of dependence, visibility, substitutability and portability. The objectives of this paper are (1) to critically evaluate proposed changes to damaged supply chains such as adding inventory, adopting standardized parts, physically duplicating line production and equipment, and evacuating whole facilities; (2) to propose \"virtual dual sourcing\" in which the firm facing supply chain disruptions caused by a disaster carefully choose either to quickly recover a damaged line or transfer critical design information to a substitute line. Effective implementation of the virtual dual solution will require simultaneously enhancing the design information's portability, the supplier's visibility, and the firm's capabilities at process recovery and production substitution.", "author_names": [ "Takahiro Fujimoto", "Youngwon Park" ], "corpus_id": 154862751, "doc_id": "154862751", "n_citations": 39, "n_key_citations": 1, "score": 0, "title": "Balancing supply chain competitiveness and robustness through \"virtual dual sourcing\" Lessons from the Great East Japan Earthquake", "venue": "", "year": 2014 }, { "abstract": "In Japan, Korea, and Taiwan, cerebrovascular and cardiovascular diseases (CVDs) caused by overwork are recognized by government as work related. These three countries are the only countries in the world that officially recognize CVDs caused by psychosocial factors (e.g. overwork) as work related cerebrovascular and cardiovascular diseases (WR CVDs) and compensate employees accordingly. The present study compared the similarities and differences among the recognition of overwork related CVDs in Japan, Korea, and Taiwan. The criteria by which WR CVDs are identified are very similar in the three countries. However, in the interval surveyed (1996 2009) Korea had a remarkably larger number of recognized WR CVD patients than did Japan or Taiwan. Recognition of occupational diseases is influenced by various factors, including socio cultural values, the nature of occupational health care schemes, the extent of the social security umbrella, national health insurance policy, and scientific evidence. Our results show that social factors may be very different among the three countries studied, although the recognition criteria for WR CVDs are quite similar.", "author_names": [ "Jungsun Park", "Yangho Kim", "Yawen Cheng", "Seichi Horie" ], "corpus_id": 20648661, "doc_id": "20648661", "n_citations": 31, "n_key_citations": 0, "score": 0, "title": "A comparison of the recognition of overwork related cardiovascular disease in Japan, Korea, and Taiwan.", "venue": "Industrial health", "year": 2012 } ]

[ { "abstract": "It has been recognized that Raman scattering spectroscopy is a powerful tool to characterize SiC crystals non destructively. We review recent significant developments in the use of Raman scattering to study structural and electronic properties of SiC crystals. The areas to be discussed in the first part include polytype identification, evaluation of stacking disorder and ion implantation damages, and stress evaluation. The Raman scattering by electronic transitions is discussed in the second part of this article. We concentrate on the plasmon LO phonon coupled modes whose spectral profiles are used to evaluate the carrier concentration and mobility. Anisotropic electronic properties of a SiC and characteristics of heavily doped crystals are discussed. Semiconductor to metal transition and Fano interference effect are also treated.", "author_names": [ "Shin-ichi Nakashima", "Hiroshi Harima" ], "corpus_id": 121826054, "doc_id": "121826054", "n_citations": 665, "n_key_citations": 10, "score": 1, "title": "Raman Investigation of SiC Polytypes", "venue": "", "year": 1997 }, { "abstract": "", "author_names": [ "Seong-Min Jeong", "Ji-Young Yoon", "Hyoung-Seuk Choi", "Dae-Seop Byeon", "Eun Jin Jung", "Yong-Jin Kwon", "Jae Whui Kim", "Younghee Kim", "Won Seon Seo", "Myung-Hyun Lee" ], "corpus_id": 111729478, "doc_id": "111729478", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Investigation of SiC Polytypes for PVT Process Control Using Ultraviolet Fluorescence Technique", "venue": "", "year": 2016 }, { "abstract": "Spatially resolved high resolution electron energy loss in a high energy resolution monochromated EELS system (HERMES) system has attracted a lot of attention after its inception while opening new avenues of research and many unanswered questions. The recent advancements in EELS have made it possible for 1 nm probe sizes while still managing high probe current of around 10 pA [1] With this, spatially resolved transmission EELS is possible, paving the way for accurately quantifying bulk vibrational mode energies and distinguishing them from surface modes. [2] It is instructive to begin with a relatively simple system whose vibrational modes can be more precisely studied than other complex systems. We have chosen SiC as the system of choice due to its simple cubic structure in its 3C polytype and hexagonal structure in its 4H and 6H polytypes. Here we discuss only the SiC 6H polytype. SiC vibrational modes have been meticulously studies previously by means of Fourier transform infra red spectroscopy and Raman spectroscopy. With a well documented database for the SiC system, we hope to correlate our findings in spatially resolved high resolution EELS. Typically, Raman spectroscopy studies the surface vibrational modes of a material due to the low penetration depth of the laser. Although transmission Raman Spectroscopy [3] is capable of probing bulk modes in a material, it lacks the spatial resolution to map local bulk modes and study thickness and size dependent effects. With our HERMES system, we can show the distinction between surface and bulk modes in a thin high quality thin film single crystal sample as well as increase in scattering probability of bulk modes as a function of thickness.", "author_names": [ "Chaitanya A Gadre", "Xingxu Yan", "Xiaoqing Pan" ], "corpus_id": 73711728, "doc_id": "73711728", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Investigation of Surface and Bulk Vibrational Modes in SiC Polytypes using Spatially Resolved Monochromated HREELS", "venue": "Microscopy and Microanalysis", "year": 2018 }, { "abstract": "We calculated the hyperfine structure and the zero field splitting parameters of divacancies in 3C, 4H and 6H SiC in the ground state and in the excited state for 4H SiC within the framework of density functional theory. Besides that our calculations provide identification of the defect in different polytypes, we can find some carbon atoms next to the divacancy that of the spin polarizations are similar in the ground and excited states. This coherent nuclear spin polarization phenomenon can be the base to utilize 13C spins as quantum memory.", "author_names": [ "Krisztian Szasz", "Viktor Ivady", "Erik Janzen", "Adam Gali" ], "corpus_id": 96534988, "doc_id": "96534988", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "First Principles Investigation of Divacancy in SiC Polytypes for Solid State Qubit Application", "venue": "", "year": 2014 }, { "abstract": "A comprehensive study on the hydrogen etching of numerous SiC polytype surfaces and orientations has been performed in a hot wall CVD reactor under both atmospheric and low pressure conditions. The polytypes studied were 4H and 6H SiC as well as 3C SiC grown on Si substrates. For the hexagonal polytypes the wafer surface orientation was both on and off axis, i.e. C and Si face. The investigation includes the influence of the prior surface polishing method on the required etching process parameters. 3C SiC was also studied grown in both the (100) and (111) orientations. After etching, the samples were analyzed via atomic force microscopy (AFM) to determine the surface morphology and the height of the steps formed. For all cases the process conditions necessary to realize a well ordered surface consisting of unit cell and sub unit cell height steps were determined. The results of these experiments are summarized and samples of the corresponding AFM analysis presented.", "author_names": [ "Christopher L Frewin", "Camilla Coletti", "Christian Riedl", "Ulrich Starke", "Stephen E Saddow" ], "corpus_id": 136934528, "doc_id": "136934528", "n_citations": 40, "n_key_citations": 1, "score": 0, "title": "A Comprehensive Study of Hydrogen Etching on the Major SiC Polytypes and Crystal Orientations", "venue": "", "year": 2009 }, { "abstract": "Raman spectroscopy was applied to investigate a series of SiC films grown on Si and 6H SiC substrates by a new method of solid gas phase epitaxy. During the growth characteristic voids are formed in Si at the SiC/Si interface. Raman peak position, intensity and linewidth were used to characterize the quality and the polytype structure of the SiC layers. A large enhancement in the peak intensity of the transverse optical and longitudinal optical phonon modes of SiC is observed for the Raman signal measured at the voids. In addition, scanning electron microscopy and atomic force microscopy were used to investigate the surface morphology of SiC layers.", "author_names": [ "Joanna Wasyluk", "Tatiana Perova", "Sergey A Kukushkin", "Andrey V Osipov", "N A Feoktistov", "S A Grudinkin" ], "corpus_id": 136354213, "doc_id": "136354213", "n_citations": 48, "n_key_citations": 2, "score": 0, "title": "Raman Investigation of Different Polytypes in SiC Thin Films Grown by Solid Gas Phase Epitaxy on Si (111) and 6H SiC Substrates", "venue": "", "year": 2010 }, { "abstract": "Among the various SiC polytypes, cubic 3C SiC is much more difficult to grow in high crystalline quality than the commercially introduced hexagonal 6H SiC and 4H SiC counterparts. Besides some benefits of 3C SiC for transistor applications related to a greater electron mobility and a lower metal oxide semiconductor interface trap density compared to 4H SiC, new potential optoelectronic applications have been introduced very recently. Boron doped 3C SiC may act as an ideal candidate for an intermediate band (IB) solar cell material. Aluminum doped p type 3C SiC could lead to the development of efficient optoelectrochemical water splitting cells. Finally, 3C SiC with its various intrinsic point defects has been considered as a suitable candidate for future spintronic applications. All these applications will critically depend on further understanding defect behaviour on atomic level. In our study we investigated free standing n type and p type 3C SiC material grown in our lab. Temperature dependent photoluminescence measurements revealed the presence of carbon vacancy related VC and VC CSi defect transitions in the p type materials but not in the n type materials. This observation present in as grown 3C SiC is believed to have significant impact on the optoelectronic applications. Copyright (c) 2017 VBRI Press.", "author_names": [ "Martin Wilhelm", "Mikael Syvajarvi", "Peter J Wellmann" ], "corpus_id": 139896851, "doc_id": "139896851", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Investigation of deep electronic levels in n type and p type 3C SiC using photoluminescence", "venue": "", "year": 2017 }, { "abstract": "SiC/AlN composites with controlled interfacial solid solution were employed in the present work for investigating the effects of interfacial bonding and AlN polytypes on the mechanical properties. Platelike AlN polytypes and interfacial bonding were found to have substantial effects on the flexural strength, hardness, and fracture toughness.", "author_names": [ "Jow-Lay Huang", "Jyh-Ming Jih" ], "corpus_id": 137485039, "doc_id": "137485039", "n_citations": 29, "n_key_citations": 0, "score": 0, "title": "Investigation of SiC AlN: Part II, Mechanical Properties", "venue": "", "year": 1996 }, { "abstract": "SiC/AlN composites with controlled interfacial solid solution were employed in this present work to investigate the effects of interfacial chemical composition and AlN polytypes on the fatigue properties. The dynamic strength of the SiC/AlN composite was found to decrease initially as the stressing rate decreased. However, the strength increased with a decrease in stress rate at a low stress rate region of below 0.01 MPa/s. Crack arrest could have occurred before exhibiting spontaneous failure at an intermediate stress rate of 0.01 MPa/s. It was found that both the interfacial bonding strength and testing technique had essential effects on the behavior of slow crack growth.", "author_names": [ "Jow-Lay Huang", "Jyh-Ming Jih" ], "corpus_id": 138887500, "doc_id": "138887500", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Investigation of SiC AlN: Part III. Static and dynamic fatigue", "venue": "", "year": 1995 }, { "abstract": "Abstract Polytypes of colourless and coloured single crystals of silicon carbide (SiC) grown on SiC substrates by chemical vapour deposition are studied using Raman spectroscopy supplemented by scanning electron microscopy (SEM) and X ray diffraction (XRD) analyses. The SEM analysis of the defect stacking faults, inclusions of defects and their distribution has shown that they correlate with the peak positions of the obtained Raman spectra and with the XRD data on the crystal structure Kopsavilkums Dazadu fazu silicija karbida (SiC) monokristali, kas audzeti uz SiC pamatnem ar kimiskas nogulsnesanas metodi no gazveida fazes, tika petiti, izmantojot Ramana spektroskopiju, skenejoso elektronu mikroskopiju (SEM) un rentgenstaru difrakciju (XRD) Ar SEM palidzibu tika identificeti kristalografiskas strukturas apgabali un ieslegumi, ir pieradits, ka tie korele ar Ramana spektru piku pozicijam, un XRD datiem par kristalisko strukturu", "author_names": [ "Georg Chikvaidze", "Nina Mironova-Ulmane", "A V Plaude", "O T Sergeev" ], "corpus_id": 122382813, "doc_id": "122382813", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Investigation of Silicon Carbide Polytypes by Raman Spectroscopy", "venue": "", "year": 2014 } ]

[ { "abstract": "1. Introduction 2. Theory of Electrons in a Non Crystalline Medium 3. Phonons and Polarons 4. The Fermi Glass and the Anderson Transition 5. Liquid Metals and Semimetals 6. Non Crystalline Semiconductors 7. Tetrahedrally Bonded Semiconductors Amorphous Germanium and Silicon 8. Aresnic and Other Three Fold Co ordinated Materials 9. Chalcogenide and Other Glasses 10. Selenium, Tellurium, and their Alloys", "author_names": [ "Nevill Francis Mott", "Edward Arthur Davis", "Kurt Weiser" ], "corpus_id": 136959916, "doc_id": "136959916", "n_citations": 7666, "n_key_citations": 370, "score": 1, "title": "Electronic Processes In Non Crystalline Materials", "venue": "", "year": 1940 }, { "abstract": "The interatomic distances in crystals of alloys cannot be accounted for by assigning a fixed atomic radius to each kind of atom, and the causes of this variation are discussed with special references to the Brillouin zone characteristics of different structures. According to the theory of Jones, the effect of an overlap across the side of a Brillouin zone is to compress the zone at right angles to the face concerned, and so to expand the crystal lattice in the same direction. This expansion is not a property of an atom which can be transferred to any of its alloys, but is a characteristic of a structure with sufficient electrons to produce an overlap. The lattice spacings of alloys of aluminium and indium with copper, silver, gold, and magnesium are examined, and the apparent sizes of the aluminium and indium atoms are discussed, and are shown to be in agreement with the theory. The previous suggestion, that in metallic aluminium the atoms exist in an incompletely ionized state, is improbable, and is no longer required in order to explain the facts. New experimental data for the lattice spacings of solid solutions of aluminium and indium are presented, and these show that, whilst the curves connecting the a parameter with the composition are smooth and continuous, the corresponding curves for the c parameter show an abrupt change in direction at about 0.75 atomic of indium or aluminium. This is taken to imply that, although in metallic magnesium with two electrons per atom, the overlap of the first Brillouin zone is in the a direction only, the structure is so near to the stage at which the c overlap sets in that the addition of less than one electron per hundred atoms causes the c overlap to take place.", "author_names": [ "William Hume-rothery", "Geoffrey Vincent Raynor" ], "corpus_id": 95024937, "doc_id": "95024937", "n_citations": 27, "n_key_citations": 0, "score": 1, "title": "The apparent sizes of atoms in metallic crystals with special reference to aluminium and indium, and the electronic state of magnesium", "venue": "Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences", "year": 1940 }, { "abstract": "IT has been recognized for many years that under certain conditions a hydrogen atom can form a connecting link between two other atoms. It may be considered as forming a bond between them, known as the hydrogen bond. Although the hydrogen bond is not strong, recent investigations have shown it to be of very wide occurrence. The concept has been extremely useful in explaining the association of polar liquids like water, the association of carboxylic acids, alcohols, amides, etc. the closure of rings within the molecule, and in interpreting many measurements of structure by X ray and electron diffraction methods and of the frequency shifts of the infra red absorption bands of certain known groupings. It was investigations of this type that not only established the existence of this form of bond but also provided information regarding the conditions in which its formation is to be expected, and, in many cases, of the actual energy of the bond. In spite of the enormous amount of experimental data now available, there is still much information which is lacking; the exact mechanism of the bonding power of the hydrogen is not clear, and there are many difficulties with questions of terminology.", "author_names": [ "Cecil Edwin Henry Bawn" ], "corpus_id": 4091627, "doc_id": "4091627", "n_citations": 372, "n_key_citations": 12, "score": 0, "title": "The Hydrogen Bond", "venue": "Nature", "year": 1940 }, { "abstract": "Since the discovery by Bohr and coworkers in 1904 of the effect of acidity on the oxygen equilibrium of hemoglobin, there have been a large number of investigations directed towards clarification of the physicochemical relationships of acid groups with the hemes in hemoglobin and its derivatives. It is the purpose of this paper to analyze modern quantitative data, including those for ferrihemoglobin (methemoglobin) in order to throw new light on the general problem, to establish the ionization constant of an acid group in ferrihemoglobin previously unrecognized, and to give a structural interpretation of shifts in the pK of groups caused by changing chemical environment.", "author_names": [ "Charles D Coryell", "Linus Pauling" ], "corpus_id": 15987925, "doc_id": "15987925", "n_citations": 48, "n_key_citations": 0, "score": 0, "title": "A STRUCTURAL INTERPRETATION OF THE ACIDITY OF GROUPS ASSOCIATED WITH THE HEMES OF HEMOGLOBIN AND HEMOGLOBIN DERIVATIVES", "venue": "", "year": 1940 }, { "abstract": "Simultaneous hemoglobin and creatinine renal clearance studies have been presented which indicate that hemoglobin is eliminated by the kidney at a rate which is 3 per cent of the creatinine clearance, above a plasma hemoglobin concentration of approximately 250 mg. per 100 cc. In dogs whose average glomerular filtration rate is 66 cc. per minute, about 2 cc. of plasma are cleared of hemoglobin per minute. A definite renal threshold exists for hemoglobin at a plasma concentration of about 100 mg. per 100 cc. below which hemoglobinuria does not occur. The uniformity of the process indicates that hemoglobinuria is not the result of a transient glomerular injury induced by the hemoglobin. It is tentatively suggested that the experimental results obtained may be interpreted in terms of the following concept. The glomerulus permits the filtration of hemoglobin in amounts directly dependent upon plasma concentration. However, only 3 per cent of all the pores of the membrane are electrostatically large enough to permit the passage of an undissociated hemoglobin molecule. Of that hemoglobin which passes down the tubule, a relatively constant though small amount is recovered by the tubules by a process not unlike that of phagocytosis found elsewhere in the body. An average value for this \"athrocytic\" capacity in a medium sized dog is 2 mg. of hemoglobin per minute. This pattern of renal hemoglobin excretion is in agreement with the principles of the modern theory of kidney function.", "author_names": [ "J Victor Monke", "Charles L Yuile" ], "corpus_id": 17698128, "doc_id": "17698128", "n_citations": 48, "n_key_citations": 0, "score": 0, "title": "THE RENAL CLEARANCE OF HEMOGLOBIN IN THE DOG", "venue": "The Journal of experimental medicine", "year": 1940 }, { "abstract": "In an attempt to determine the fraction of ions lost by recombination in an x ray ionization chamber, a theory has been developed for the processes involved in preferential and initial ionic and electronic recombination. The theory considers the change of the energy distribution of the electrons as they diffuse away from the parent atom. From this, together with a knowledge of the electron capture process, the space distribution of negative ions formed may be obtained. The probability of the initial electron recombining preferentially with the parent positive ion is considered as well as the preferential process for the negative ion. Knowing the initial spacing of the ions, it is possible to calculate the recombination occurring during the diffusion process until random distribution is reached. The final volume recombination may then be calculated in the usual manner. The theory may be employed in both electronegative and free electron gases and to ions formed in the presence or absence of an electric field.", "author_names": [ "Norris E Bradbury" ], "corpus_id": 98624758, "doc_id": "98624758", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Preferential and Initial Ionic Recombination in Gases", "venue": "", "year": 1940 }, { "abstract": "The reaction chosen for the determination was the decomposition of nitrogen iodide in dilute hydriodic acid according to the equation (with excess hydriodic acid present) 2NH3.NI3 5HI 2NH4I 3HI3. This reaction has the advantage that it is unnecessary to prepare the nitrogen iodide in the dry state, a difficulty met with in the method involving the detonation of the substance in some form of bomb calorimeter, quite apart from the complexity of the reaction products in that case. The reaction with hydriodic acid proceeds rapidly, and appears to be quantitative (Chattaway and Orton 1899) A difficulty was encountered when analyses were made of the final products, as it was found that the amount of ammonia obtained was greater than that corresponding to the composition NH3.NI3. Since the excess varied quite considerably from sample to sample, it was considered to be adsorbed or loosely combined ammonia, such as is frequently met with in compounds containing ammonia. The existence of higher ammines of NI3 lends support to this view. To overcome the difficulty introduced by this excess of which the state of combination and heat content were unknown, and which it was not considered correct to treat as free ammonia, advantage was taken of the fact that the proportion of excess ammonia could be varied quite considerably. The experiments were considered in pairs, the effect of the excess ammonia being eliminated between them.", "author_names": [ "F R Meldrum" ], "corpus_id": 93804049, "doc_id": "93804049", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The heat of formation of nitrogen iodide", "venue": "Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences", "year": 1940 }, { "abstract": "a catalogue of diseases, drugs and doses, or even analyses of results achieved, as an impression of the general trend of antispecific therapy, and an indication of the significance and importance of the far reaching changes which the last twenty, and more especially the last five, years have inaugurated. In the case of gonorrhoea and chancroid, the changes in treatment have been greater and more striking than in the case of syphilis. The treatment of syphilis is still carried on mainly by the intravenous or intramuscular injection of trivalent arsenical compounds such as neoarsphenamine or \" 914 \" and stabilarsan, and the intramuscular injection of bismuth metal", "author_names": [ "R C L Batchelor" ], "corpus_id": 4724410, "doc_id": "4724410", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Modern Therapy in Specific Infections A Honyman Gillespie Lecture delivered on 25th April 1940.", "venue": "Edinburgh medical journal", "year": 1940 }, { "abstract": "", "author_names": [ "S J Kramer" ], "corpus_id": 92966199, "doc_id": "92966199", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Effect of substituents on the electronegativity of the naphthyl radicals", "venue": "", "year": 1940 }, { "abstract": "", "author_names": [ "Ed F Degering", "Karl Schaff", "Leslie Gillette" ], "corpus_id": 100890715, "doc_id": "100890715", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A consideration of the concepts of relative electronegativity", "venue": "", "year": 1940 } ]

[ { "abstract": "Machine vision technology has taken huge leaps in recent years, and is now becoming an integral part of various intelligent systems, including autonomous vehicles and robotics. Usually, visual information is captured by a frame based camera, converted into a digital format and processed afterwards using a machine learning algorithm such as an artificial neural network (ANN) 1 The large amount of (mostly redundant) data passed through the entire signal chain, however, results in low frame rates and high power consumption. Various visual data preprocessing techniques have thus been developed 2 7 to increase the efficiency of the subsequent signal processing in an ANN. Here we demonstrate that an image sensor can itself constitute an ANN that can simultaneously sense and process optical images without latency. Our device is based on a reconfigurable two dimensional (2D) semiconductor 8 9 photodiode 10 12 array, and the synaptic weights of the network are stored in a continuously tunable photoresponsivity matrix. We demonstrate both supervised and unsupervised learning and train the sensor to classify and encode images that are optically projected onto the chip with a throughput of 20 million bins per second. A two dimensional semiconductor photodiode array senses and processes optical images simultaneously without latency, and is trained to classify and encode images with high throughput, acting as an artificial neural network.", "author_names": [ "Lukas Mennel", "Joanna Karolina Symonowicz", "Stefan Wachter", "Dmitry K Polyushkin", "Aday J Molina-Mendoza", "T Mueller" ], "corpus_id": 212407759, "doc_id": "212407759", "n_citations": 117, "n_key_citations": 2, "score": 0, "title": "Ultrafast machine vision with 2D material neural network image sensors", "venue": "Nature", "year": 2020 }, { "abstract": "Abstract Over the years little research has been performed for vision based papaya disease recognition system in order to help distant farmers, most of whom require proper support for cultivation. Due to advancement of vision based technology we find a good solution to this problem. Papaya disease recognition mainly involves two challenging problems: one is disease detection and another is disease classification. Considering this scenario, here we present an online machine vision based agro medical expert system that processes an image captured through mobile or handheld device and determines the diseases in order to help distant farmers to address the problem. Some experiments are performed to show the utility of the proposed expert system. First, we propose a set of features from the view point of distinguishing attributes. K means clustering algorithm is used in order to segment out the disease attacked region from the captured image and then required features are extracted to classify the diseases with the help of support vector machine. More than 90% classification accuracy has been achieved, which appears to be good as well as promising by comparing performances obtained with recently reported relevant works.", "author_names": [ "Md Tarek Habib", "Anup Majumder", "Atm Jakaria", "Morium Akter", "Mohammad Shorif Uddin", "Farruk Ahmed" ], "corpus_id": 67110501, "doc_id": "67110501", "n_citations": 43, "n_key_citations": 3, "score": 0, "title": "Machine vision based papaya disease recognition", "venue": "J. King Saud Univ. Comput. Inf. Sci.", "year": 2020 }, { "abstract": "An image sensor array has been developed that acts as its own artificial neural network to capture and identify optical images simultaneously, processing the information rapidly without needing to convert it to a digital format. An array of photosensors that acts as an artificial neural network.", "author_names": [ "Yang Chai" ], "corpus_id": 212407322, "doc_id": "212407322", "n_citations": 25, "n_key_citations": 0, "score": 0, "title": "In sensor computing for machine vision", "venue": "Nature", "year": 2020 }, { "abstract": "Abstract With being rapid increasing population in worldwide, the need for satisfactory level of crop production with decreased amount of agricultural lands. Machine vision would ensure the increase of crop production by using an automated, non destructive and cost effective technique. In last few years, remarkable results have been achieved in different sectors of agriculture. These achievements are integrated with machine learning techniques on machine vision approach that cope with colour, shape, texture and spectral analysis from the image of objects. Despite having many applications of different machine learning techniques, this review only described the statistical machine learning technologies with machine vision systems in agriculture due to broad area of machine learning applications. Two types of statistical machine learning techniques such as supervised and unsupervised learning have been utilized for agriculture. This paper comprehensively surveyed current application of statistical machine learning techniques in machine vision systems, analyses each technique potential for specific application and represents an overview of instructive examples in different agricultural areas. Suggestions of specific statistical machine learning technique for specific purpose and limitations of each technique are also given. Future trends of statistical machine learning technology applications are discussed.", "author_names": [ "Tanzeel Ur Rehman", "Md Sultan Mahmud", "Young K Chang", "Jian Jin", "Jaemyung Shin" ], "corpus_id": 59523924, "doc_id": "59523924", "n_citations": 89, "n_key_citations": 3, "score": 0, "title": "Current and future applications of statistical machine learning algorithms for agricultural machine vision systems", "venue": "Comput. Electron. Agric.", "year": 2019 }, { "abstract": "A new technique for three dimensional (3D) camera calibration for machine vision metrology using off the shelf TV cameras and lenses is described. The two stage technique is aimed at efficient computation of camera external position and orientation relative to object reference coordinate system as well as the effective focal length, radial lens distortion, and image scanning parameters. The two stage technique has advantage in terms of accuracy, speed, and versatility over existing state of the art. A critical review of the state of the art is given in the beginning. A theoretical framework is established, supported by comprehensive proof in five appendixes, and may pave the way for future research on 3D robotics vision. Test results using real data are described. Both accuracy and speed are reported. The experimental results are analyzed and compared with theoretical prediction. Recent effort indicates that with slight modification, the two stage calibration can be done in real time.", "author_names": [ "Roger Y Tsai" ], "corpus_id": 12178672, "doc_id": "12178672", "n_citations": 6373, "n_key_citations": 317, "score": 1, "title": "A versatile camera calibration technique for high accuracy 3D machine vision metrology using off the shelf TV cameras and lenses", "venue": "IEEE J. Robotics Autom.", "year": 1987 }, { "abstract": "Abstract Weeds are among the major factors that could harm crop yield. With the advances in electronic and information technologies, machine vision combined with image processing techniques has become a promising tool for precise real time weed and crop detection in the field, providing valuable sensing information for site specific weed management. This review summarized the advances of weed detection using ground based machine vision and image processing techniques. Concretely, the four procedures, i.e. pre processing, segmentation, feature extraction and classification, for weed detection were presented in detail. To separate vegetation from background, different color indices and classification approaches like color index based, threshold based and learning based ones, were developed. The difficulty of weed detection lies in discriminating between crops and weeds that often have similar properties. Generally, four categories of features, i.e. biological morphology, spectral features, visual textures and spatial contexts, were used for the task, which were discussed in this review. Application of conventional machine learning based and recently developed deep learning based approaches for weed detection were also presented. Finally, challenges and solutions provided by researchers for weed detection in the field, including occlusion and overlap of leaves, varying lighting conditions and different growth stages, were discussed.", "author_names": [ "Aichen Wang", "Wen Zhang", "Xinhua Wei" ], "corpus_id": 68236928, "doc_id": "68236928", "n_citations": 93, "n_key_citations": 3, "score": 0, "title": "A review on weed detection using ground based machine vision and image processing techniques", "venue": "Comput. Electron. Agric.", "year": 2019 }, { "abstract": "1 Introduction. 2 The digitized image and its properties. 3 Data structures for image analysis. 4 Image pre processing. 5 Segmentation. 6 Shape representation and description. 7 Object recognition. 8 Image understanding. 9 3D Vision. 10 Mathematical morphology. 11 Linear discrete image transforms. 12 Image data compression. 13 Texture. 14 Motion analysis.", "author_names": [ "Milan Sonka", "Vaclav Hlavac", "Roger D Boyle" ], "corpus_id": 20993687, "doc_id": "20993687", "n_citations": 5855, "n_key_citations": 290, "score": 0, "title": "Image Processing, Analysis and Machine Vision", "venue": "Springer US", "year": 1993 }, { "abstract": "Machine vision for plant phenotyping is an emerging research area for producing high throughput in agriculture and crop science applications. Since 2D based approaches have their inherent limitations, 3D plant analysis is becoming state of the art for current phenotyping technologies. We present an automated system for analyzing plant growth in indoor conditions. A gantry robot system is used to perform scanning tasks in an automated manner throughout the lifetime of the plant. A 3D laser scanner mounted as the robot's payload captures the surface point cloud data of the plant from multiple views. The plant is monitored from the vegetative to reproductive stages in light/dark cycles inside a controllable growth chamber. An efficient 3D reconstruction algorithm is used, by which multiple scans are aligned together to obtain a 3D mesh of the plant, followed by surface area and volume computations. The whole system, including the programmable growth chamber, robot, scanner, data transfer, and analysis is fully automated in such a way that a naive user can, in theory, start the system with a mouse click and get back the growth analysis results at the end of the lifetime of the plant with no intermediate intervention. As evidence of its functionality, we show and analyze quantitative results of the rhythmic growth patterns of the dicot Arabidopsis thaliana (L. and the monocot barley (Hordeum vulgare L. plants under their diurnal light/dark cycles.", "author_names": [ "Ayan Chaudhury", "Christopher D W Ward", "Ali Talasaz", "Alexander G Ivanov", "Mark Brophy", "Bernard Grodzinski", "Norman P A Huner", "Rajnikant V Patel", "John L Barron" ], "corpus_id": 12424213, "doc_id": "12424213", "n_citations": 36, "n_key_citations": 1, "score": 0, "title": "Machine Vision System for 3D Plant Phenotyping", "venue": "IEEE/ACM Transactions on Computational Biology and Bioinformatics", "year": 2019 }, { "abstract": "Machine vision for precision agriculture has attracted considerable research interest in recent years. The aim of this paper is to review the most recent work in the application of machine vision to agriculture, mainly for crop farming. This study can serve as a research guide for the researcher and practitioner alike in applying cognitive technology to agriculture. Studies of different agricultural activities that support crop harvesting are reviewed, such as fruit grading, fruit counting, and yield estimation. Moreover, plant health monitoring approaches are addressed, including weed, insect, and disease detection. Finally, recent research efforts considering vehicle guidance systems and agricultural harvesting robots are also reviewed.", "author_names": [ "Efthimia Mavridou", "Eleni Vrochidou", "George A Papakostas", "Theodore P Pachidis", "Vassilis G Kaburlasos" ], "corpus_id": 209316161, "doc_id": "209316161", "n_citations": 35, "n_key_citations": 0, "score": 0, "title": "Machine Vision Systems in Precision Agriculture for Crop Farming", "venue": "J. Imaging", "year": 2019 }, { "abstract": "Significance Plant stress identification based on visual symptoms has predominately remained a manual exercise performed by trained pathologists, primarily due to the occurrence of confounding symptoms. However, the manual rating process is tedious, is time consuming, and suffers from inter and intrarater variabilities. Our work resolves such issues via the concept of explainable deep machine learning to automate the process of plant stress identification, classification, and quantification. We construct a very accurate model that can not only deliver trained pathologist level performance but can also explain which visual symptoms are used to make predictions. We demonstrate that our method is applicable to a large variety of biotic and abiotic stresses and is transferable to other imaging conditions and plants. Current approaches for accurate identification, classification, and quantification of biotic and abiotic stresses in crop research and production are predominantly visual and require specialized training. However, such techniques are hindered by subjectivity resulting from inter and intrarater cognitive variability. This translates to erroneous decisions and a significant waste of resources. Here, we demonstrate a machine learning framework's ability to identify and classify a diverse set of foliar stresses in soybean [Glycine max (L. Merr. with remarkable accuracy. We also present an explanation mechanism, using the top K high resolution feature maps that isolate the visual symptoms used to make predictions. This unsupervised identification of visual symptoms provides a quantitative measure of stress severity, allowing for identification (type of foliar stress) classification (low, medium, or high stress) and quantification (stress severity) in a single framework without detailed symptom annotation by experts. We reliably identified and classified several biotic (bacterial and fungal diseases) and abiotic (chemical injury and nutrient deficiency) stresses by learning from over 25,000 images. The learned model is robust to input image perturbations, demonstrating viability for high throughput deployment. We also noticed that the learned model appears to be agnostic to species, seemingly demonstrating an ability of transfer learning. The availability of an explainable model that can consistently, rapidly, and accurately identify and quantify foliar stresses would have significant implications in scientific research, plant breeding, and crop production. The trained model could be deployed in mobile platforms (e.g. unmanned air vehicles and automated ground scouts) for rapid, large scale scouting or as a mobile application for real time detection of stress by farmers and researchers.", "author_names": [ "Sambuddha Ghosal", "David Blystone", "Asheesh K Singh", "Baskar Ganapathysubramanian", "Arti Singh", "Soumik Sarkar" ], "corpus_id": 4951327, "doc_id": "4951327", "n_citations": 189, "n_key_citations": 4, "score": 0, "title": "An explainable deep machine vision framework for plant stress phenotyping", "venue": "Proceedings of the National Academy of Sciences", "year": 2018 } ]

[ { "abstract": "For many innovative applications a significant improvement in the homogeneity of the laser beam is a critical requirement when using semiconductor lasers. There are several different methods for the homogenization of laser radiation. Homogenization using micro cylinder lens arrays is a considerably elegant and compact solution. In this case the incident laser beam is separated into partial beams by one or more micro lens arrays. These partial beams are then overlaid in the homogenization plane by the downstream optics. Depending on the arrangement and geometry of the micro lenses, this enables homogeneously illuminated lines, rectangles or squares to be generated. The major advantage of this solution lies in the increased freedom of adjustment to account for the initial beam profile, as well as the extremely compact design. In addition to a comparison of different homogenization principles the paper describes new approaches of homogenization via micro lens arrays and compares the impact on the array performance by different manufacturing approaches.", "author_names": [ "Volker Sinhoff", "Stefan Hambuecker", "Klaus R F Kleine", "Olaf Ruebenach", "Christian Wessling" ], "corpus_id": 123647340, "doc_id": "123647340", "n_citations": 8, "n_key_citations": 0, "score": 1, "title": "Micro lens arrays for laser beam homogenization and transformation", "venue": "Photonics West Lasers and Applications in Science and Engineering", "year": 2013 }, { "abstract": "Micro Lens Arrays (MLA) containing thousands of lenses with an aspheric shape and a precise position on large substrates are used in sensor devices directly or as master moulds for the low cost replication of micro lenses in an array. They have to fulfill the high requirements in wafer scale manufacturing of small optics. This high volume manufacturing method for low cost but effective micro optics relies on the sandwich like assembly of the sensors and optical components like lenses as well as mechanical components like apertures and spacers on wafer level. After joining all components the dicing results in a batch of wafer level cameras for the use in cellular phones or webcams. Micro Lens Arrays are also a centrepiece of today's sensor products, either to raise the fill factor and collect more light on each pixel or to deflect the incoming beam to measure the aberrations of the wavefront, the working principle of the Hartmann Shack sensor. Within illumination optics, MLA are commonly used for beam homogenization in projection systems. In all fields of application ranging from automotive, medical, consumer and industrial optics to high end sensors for space instrumentation, high quality lens arrays for direct use or replication must be provided.", "author_names": [], "corpus_id": 170075670, "doc_id": "170075670", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Micro Lens Array Milling on Large Wafers More Design Freedom for Micro Optics Aspheric Lenslets with Imaging Quality", "venue": "", "year": 2009 }, { "abstract": "Micro Lens Arrays (MLA) containing thousands of lenses with an aspheric shape and a precise position on large substrates are used in sensor devices directly or as master moulds for the low cost replication of micro lenses in an array. They have to fulfill the high requirements in wafer scale manufacturing of small optics. This high volume manufacturing method for low cost but effective micro optics relies on the sandwich like assembly of the sensors and optical components like lenses as well as mechanical components like apertures and spacers on wafer level. After joining all components the dicing results in a batch of wafer level cameras for the use in cellular phones or webcams. Micro Lens Arrays are also a centrepiece of today's sensor products, either to raise the fill factor and collect more light on each pixel or to deflect the incoming beam to measure the aberrations of the wavefront, the working principle of the Hartmann Shack sensor. Within illumination optics, MLA are commonly used for beam homogenization in projection systems. In all fields of application ranging from automotive, medical, consumer and industrial optics to high end sensors for space instrumentation, high quality lens arrays for direct use or replication must be provided.", "author_names": [ "Sebastian Scheiding", "Andreas Gebhardt", "Ramona Eberhardt", "Andreas Tunnermann" ], "corpus_id": 111115622, "doc_id": "111115622", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Micro Lens Array Milling on Large Wafers", "venue": "", "year": 2009 }, { "abstract": "Abstract A laser micro bonding process using laser beam shaping is successfully demonstrated for flexible printed circuit boards. A CW Ytterbium fiber laser with a wavelength of 1070 nm and a laser power density of 1 7 W/mm 2 is employed as a local heat source for bonding flexible printed circuit boards to rigid printed circuit boards. To improve the bonding quality, a micro lens array is used to modify the Gaussian laser beam for the bonding process. An electromagnetic modeling and heat transfer simulation is conducted to verify the effect of the micro lens array on the laser bonding process. The optimal bonding parameters are found experimentally. As the measured temperature ramp rate of the boards exceeds 1100 K/s, bonding occurs within 100 200 ms at a laser power density of 5 W/mm 2 The bonding quality of the FPCB is verified with a shear strength test. Process characteristics are also discussed.", "author_names": [ "Joohan Kim", "Hae woon Choi" ], "corpus_id": 108639077, "doc_id": "108639077", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Flexible printed circuit boards laser bonding using a laser beam homogenization process", "venue": "", "year": 2012 }, { "abstract": "Formed microlens array by different microlens according to a probability distribution, forms a light beam having a predetermined intensity distribution in a predetermined far field scatter pattern within. This difference in the micro lens comprises a random deviation in the sag profile corresponding to the surface shape of the microlens boundary profile corresponding to a boundary of the microlenses, and a spatial distribution corresponding to the relative position of the microlens in the array. Sag distribution deviation may be used to equalize the intensity distribution of the light beam. Border distribution deviation of irregular spatial distribution can be used to provide a predetermined intensity distribution of the light beam in a predetermined scattering pattern.", "author_names": [ "tatsuso aru emu serusu" ], "corpus_id": 126086339, "doc_id": "126086339", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Random microlens array for beam shaping and homogenization", "venue": "", "year": 2003 }, { "abstract": "The paper details a square core fiber beam delivery design utilizing a unique micro lens array launch method. The paper includes the resulting performance of a prototype created to verify the design and its stability with an emphasis on homogenization as the fiber is articulated.", "author_names": [ "Todd E Lizotte", "Fred M Dickey" ], "corpus_id": 110392031, "doc_id": "110392031", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "MLA fiber injection for a square core fiber optic beam delivery system: design versus prototype results", "venue": "International Optical Design Conference", "year": 2010 }, { "abstract": "With the application of source mask optimization (SMO) technology in the 28nm and below nodes photolithography machine, the freeform pupil illumination technology has been widely utilized to achieve resolution enhancement for various complex patterns. The freeform illumination module (FIM) equipped with micro mirror array (MMA) are proposed, which could realize arbitrary pupil by adjusting the angle position distribution of MMA. Therefore, it is necessary to research the freeform pupil illumination technology in immersion photolithography machine. An excellent performance optical system for FIM mainly including homogenization unit, micro lens array (MLA) MMA and Fourier transform lens is proposed in this paper. The homogenization unit is used to increase the uniformity of the beam incident onto MMA. The beam incident onto MLA is divided and focused on MMA. The focused sub beams are reflected by micro mirrors and then incident into Fourier transform lens. And the freeform pupil is generated at its back focal plane. In order to verify the feasibility of the designed optical system, three freeform pupils optimized by SMO are input into the designed FIM and the corresponding simulated pupils are exported. Furthermore, the photolithography performance simulations of the optimized and simulated pupils are implemented in optical model. The results indicate that their critical dimension (CD) differences are less than 0.5nm RMS for thousands of patterns in 40nm 80nm, such as line end, line space, contact hole, end to line, SRAM et. al. which shows that the excellent performance of the designed FIM.", "author_names": [ "Zongshun Zeng", "Zhiyuan Niu", "Fang Zhang", "Xiaozhe Ma", "Siyu Zhu", "Weijie Shi", "Aijun Zeng", "Huijie Huang" ], "corpus_id": 139501696, "doc_id": "139501696", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "An excellent performance optical system for freeform pupil illumination module in immersion photolithography machine", "venue": "Other Conferences", "year": 2018 }, { "abstract": "For systems based on array source, owing to discrete single sources in the array, variation in power intensity can usually be detected as the receiving end moves. Although uniform illumination in lighting system has been widely investigated, its implemented light sources are commonly LEDs with Lambertian distribution. We further study an optical design applied for optical wireless communication system with VCSEL in this article. The optical system mainly consists of collimating lens and micro lens array to homogenize power intensity of the communication system based on VCSEL array source which has a Gaussian distribution. Our proposed scheme was verified with commercial optical design software Zemax. The simulation result shows that illumination uniformity can reach up to 91% after passing through this optical system, which can fulfill the requirements of high power uniformity in practical applications. The homogenization of power intensity solves the issue of signal power variation at the moving receiver end in optical wireless communication system, which guarantees stable communication link and robust system performance.", "author_names": [ "Xin Mu", "Zixian Wei", "Sailong Wu", "Zhenmin Chen", "Ying Dong", "Hongyan Fu" ], "corpus_id": 86642678, "doc_id": "86642678", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Homogenization of power intensity based on micro lens array in optical wireless communication systems", "venue": "Other Conferences", "year": 2019 }, { "abstract": "Abstract This paper demonstrates the formation of high fill factor plano convex cylindrical and dome type micro lens arrays on fused silica glass surface using CO2 laser assisted reshaping technique. Cylindrical micro lens array is fabricated by polishing the femtosecond laser engraved linear micro gratings by a CO2 laser beam. Initially, a femtosecond laser beam has been irradiated on the surface of the fused silica glass samples to fabricate periodic micro gratings on the glass surface. Afterwards, these micro gratings encoded glass samples are polished several times by a CO2 laser beam. As a result, plano convex cylindrical micro lens arrays with the lens period varying from 20 mm to 50 mm are developed on the glass surface. Similarly, dome type micro lens array is achieved by femtosecond laser assisted fabrication of periodic micro pillars followed by several times CO2 laser polishing. We report the formation of a large variety of dome shape micro lens array with lens size varying from 20 mm x 20 mm to 50 mm x 50 mm. The fabricated micro lenses show great consistency in size and shape throughout the sample area. We also investigate the intensity distribution of light passed through the micro lens engraved glass samples. Using the dome type micro lens array engraved glass samples, a Gaussian laser beam has been converted to a flat top laser beam for selective patterning of a thin indium tin oxide coating from fused silica glass surface.", "author_names": [ "Ik-Bu Sohn", "Hun-Kook Choi", "Young Chul Noh", "Jongyeol Kim", "Md Shamim Ahsan" ], "corpus_id": 140055432, "doc_id": "140055432", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Laser assisted fabrication of micro lens array and characterization of their beam shaping property", "venue": "Applied Surface Science", "year": 2019 }, { "abstract": "", "author_names": [ "Pei Xian Zi Pei Xian-zi", "Liang Yong Hao Liang Yong-hao", "Wang Fei Wang Fei", "Zhu Xiao Li Zhu Xiaoli", "Xie Chang Qing Xie Changqing" ], "corpus_id": 132654552, "doc_id": "132654552", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Beam Homogenization of a Fresnel Lens Array with a Randomly Distributed Phase for Laser Beams", "venue": "", "year": 2019 } ]

[ { "abstract": "Miniature power semiconductor devices mounted on printed circuit boards (PCBs) are normally cooled by means of PCB vias, copper pads, and/or heatsinks. Various reference PCB thermal designs have been provided by semiconductor manufacturers and researchers. However, the recommendations are not optimal, and there are some discrepancies among them, which may confuse electrical engineers. This paper aims to develop analytical thermal resistance models for PCB vias and pads, and further to obtain the optimal design for thermal resistance minimization. First, the PCB via array is thermally modeled in terms of multiple design parameters. A systematic parametric analysis leads to an optimal trajectory for the via diameter at different PCB specifications. Then, an axisymmetric thermal resistance model is developed for PCB thermal pads where the heat conduction, convection, and radiation all exist; due to the interdependence between the conductive/radiative heat transfer coefficients and the board temperatures, an algorithm is proposed to fast obtain the board ambient thermal resistance and to predict the semiconductor junction temperature. Finally, the proposed thermal models and design optimization algorithms are verified by computational fluid dynamics simulations and experimental measurements.", "author_names": [ "Yanfeng Shen", "Huai Wang", "Frede Blaabjerg", "Teng Long" ], "corpus_id": 181419134, "doc_id": "181419134", "n_citations": 8, "n_key_citations": 1, "score": 1, "title": "Thermal Modeling and Design Optimization of PCB Vias and Pads", "venue": "IEEE Transactions on Power Electronics", "year": 2020 }, { "abstract": "The relevant cooling action ensured by the thermal vias in PCB based power circuits allows extending the operating conditions of the semiconductor devices. However, to properly drain off the power dissipated in the active regions, efficient thermal designs must be developed. To further reduce the devices operating temperature, a strategy to take advantage of the unexploited PCB areas surrounding the device footprint is proposed and discussed in this paper. The analysis is carried out by means of 3 D FEM thermal simulations performed in the COMSOL Multiphysics environment. This investigation is devoted to providing guidelines for an optimum design of thermal vias by accounting for their main geometrical features.", "author_names": [ "Antonio Pio Catalano", "Roberto Trani", "Ciro Scognamillo", "Vincenzo d'Alessandro", "Alberto Castellazzi" ], "corpus_id": 220939289, "doc_id": "220939289", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Optimization of Thermal Vias Design in PCB Based Power Circuits", "venue": "2020 21st International Conference on Thermal, Mechanical and Multi Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)", "year": 2020 }, { "abstract": "Abstract Lead free tin based solder joints often have a single grained structure with random orientation and highly anisotropic properties. These alloys are typically stiffer than lead based solders, hence transfer more stress to printed circuit boards (PCBs) during thermal cycling. This may lead to cracking of the PCB laminate close to the solder joints, which could increase the PCB flexibility, alleviate strain on the solder joints, and thereby enhance the solder fatigue life. If this happens during accelerated thermal cycling it may result in overestimating the lifetime of solder joints in field conditions. In this study, the grain structure of SAC305 solder joints connecting ceramic resistors to PCBs was studied using polarized light microscopy and was found to be mostly single grained. After thermal cycling, cracks were observed in the PCB under the solder joints. These cracks were likely formed at the early stages of thermal cycling prior to damage initiation in the solder. A finite element model incorporating temperature dependant anisotropic thermal and mechanical properties of single grained solder joints is developed to study these observations in detail. The model is able to predict the location of damage initiation in the PCB and the solder joints of ceramic resistors with reasonable accuracy. It also shows that the PCB cracks of even very small lengths may significantly reduce accumulated creep strain and creep work in the solder joints. The proposed model is also able to evaluate the influence of solder anisotropy on damage evolution in the neighbouring (opposite) solder joints of a ceramic resistor.", "author_names": [ "Saeed Akbari", "Andreas Lovberg", "Per-Erik Tegehall", "Klas Brinkfeldt", "Dag Andersson" ], "corpus_id": 115600948, "doc_id": "115600948", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Effect of PCB cracks on thermal cycling reliability of passive microelectronic components with single grained solder joints", "venue": "Microelectronics Reliability", "year": 2019 }, { "abstract": "This work proposes analytical thermal models for through PCB thermal vias and passive heat sinks, two key components of the overall junction to ambient thermal resistance in modern integrated power electronics circuits based on advanced wide band gap semiconductor technology. The proposed models aim to support the thermal design of PCB and cooling system by the quick estimation of their thermal resistances. The models are scalable in that they fully include the geometry, material properties and boundary conditions. As a case study, reference is made to the cooling of last generation gallium nitride HEMTs in SMD type package. Here, only the static behavior is considered. The models accuracy is evaluated by comparison with accurate FEM simulations performed exploiting the commercial software COMSOL Multiphysics aided by a MATLAB routine developed by the authors.", "author_names": [ "Antonio Pio Catalano", "Roberto Trani", "Alberto Castellazzi", "Vincenzo d'Alessandro" ], "corpus_id": 208882126, "doc_id": "208882126", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Analytical Modeling of Through PCB Thermal Vias and Heat Sinks for Integrated Power Electronics", "venue": "2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)", "year": 2019 }, { "abstract": "This paper investigates an original multiphysics KB modeling of the electrothermomechanical (ETM) phenomena in a multi layer printed circuit board (PCB) under heat cycle aggression. The coupled thermal and intrinsic mechanical interactions with the PCB electrical response are analyzed. The via interconnect line (IL) junction fatigue caused by the mechanical tensions is explained with tensorial equations. The ETM effects transduced between the PCB components are modeled with equivalent graphs. The multiphysics problem general tensorial relation is formulated. To validate the Kron Branin model, the numerical application of three layer PCB proof of concept under thermal cycle aggression with 0 to 70 degC variation is introduced. The tensile stresses induced by the thermal effect on the vias and ILs are calculated. The via cracking fatigue model is approximated. The PCB voltage transfer function and input impedance in the function of the thermal aggression are discussed.", "author_names": [ "Z Xu", "Blaise Ravelo", "Olivier Maurice" ], "corpus_id": 164460851, "doc_id": "164460851", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Multiphysics Tensorial Network Analysis Applied to PCB Interconnect Fatigue Under Thermal Cycle Aggression", "venue": "IEEE Transactions on Electromagnetic Compatibility", "year": 2019 }, { "abstract": "Light emitting diodes (LEDs) have increasingly replaced conventional lamps in the fields of general lighting and consumer electronics. In addition to the sharp price fall, this is also due to the significantly higher energy efficiency and the smaller, more compact design. Recently, their robustness and reliability have also reached a level of quality that surpasses the characteristics of conventional light sources such as halogen and fluorescent lamps. Characteristics, such as excellent design freedom and the possibility for functional integration, highlight the main qualities of molded interconnect devices (MIDs) The use of this technology does not only open doors to extend the application field of LEDs to new products but also presents challenges to the lighting industry. There are many studies dealing with the reliability of LEDs as well as with the usability of the MID technology in different fields. But, the lack of experience from the manufacturers regarding the behavior of this interesting configuration (LED/MID) over the entire life cycle prevents this technology from establishing and consolidating its existence. As LEDs in the automotive sector, especially within headlamps, assume increasingly powerful lighting tasks and are no longer used exclusively for signal transfer or for displays, thermal properties of the substrate materials and the thermo mechanical behavior of the assembly are particularly relevant. In this context, this paper presents a deep and detailed reliability investigation of this system (LED/MID) and examines the influence of the MID substrate choice on the long term performance of the LED. The impact of the forward current and of the ambient temperature on the junction temperature of the LED is a proven fact. Therefore, the MID effect was inspected under different operating conditions based on infrared thermography. After analyzing the occurred failure mechanisms, by means of X ray analysis, thermal transient testing and microscopy, the resulting lifetime model is also presented and discussed.", "author_names": [ "Mahdi Soltani", "Moritz Freyburger", "Romit Kulkarni", "Rainer Mohr", "Tobias Groezinger", "Andre Zimmermann" ], "corpus_id": 52929399, "doc_id": "52929399", "n_citations": 9, "n_key_citations": 2, "score": 0, "title": "Reliability Study and Thermal Performance of LEDs on Molded Interconnect Devices (MID) and PCB", "venue": "IEEE Access", "year": 2018 }, { "abstract": "This study focuses on the onset of plastic flow in different copper raw materials. The tested copper sheets varied in the way in which they were manufactured and in terms of their post manufacturing treatments, namely annealing. Tensile tests were conducted at various temperatures (24degC, 60degC, 100degC, 150degC) in a temperature controlled chamber on thin copper specimens. Each material was analysed in its raw form as received from the manufacturer and additionally in an annealed form for comparison. These additional specimens were annealed for 1 hour at 250degC in a reflow oven. The results showed that the onset of plastic flow depends strongly on the manufacturing condition of the copper materials.", "author_names": [ "Adam Yuile", "Steffen Wiese" ], "corpus_id": 44183326, "doc_id": "44183326", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "The influence of thermal ageing on the flow stress of copper traces on PCB's", "venue": "2018 19th International Conference on Thermal, Mechanical and Multi Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)", "year": 2018 }, { "abstract": "This paper investigates different thermal management solutions for GaN HEMT mounted on Printed Circuit Board (PCB) substrates. Wide bandgap (WBG) power semiconductors like GaN devices have the ability to operate at high switching frequency (from few 100 kHz to several MHz) To take advantage of their high frequency switching capabilities, the parasitic inductances of power connections as well as the connections between the dies and the gate driver must be minimized. So the majority of GaN chips available on the market are packaged so that they can be directly attached to a PCB. The embedding technology of GaN dies in PCB substrate is attractive because it offers various interconnection possibilities. However, the low thermal conductivity of glass epoxy will result in high thermal resistance of the substrate. So it is of the first importance to seek technological means in order to improve the cooling of GaN chips soldered or embedded in such PCB structures.", "author_names": [ "Shuangfeng Zhang", "Eric Laboure", "Denis Labrousse", "Stephane Lefebvre" ], "corpus_id": 36330025, "doc_id": "36330025", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Thermal management for GaN power devices mounted on PCB substrates", "venue": "2017 IEEE International Workshop On Integrated Power Packaging (IWIPP)", "year": 2017 }, { "abstract": "QFN packages gained popularity among the industry due to its low cost, compact size, and excellent thermal electrical performance. Although PCBs are widely used for QFN packages in handheld devices, some customers require it for heavy industrial application demanding thicker PCB. When an electronic device is turned off and then turned on multiple times, it creates a loading condition called power cycling. The die is the only heat source causing non uniform temperature distribution. The solder joint reliability assessment of Quad Flat no lead Package (QFN) is done using Finite element analysis (FEA) under two different loads. In this paper, the power cycling and thermal cycling act as a combined load. The reliability assessment is done to check stress distribution on PCB boards and solder joint. The life to failure is determined for QFN package assembly. Also, three different QFN boards were used for analysis and comparison has been done to investigate the impact of thickness and copper content of board on solder joint reliability under power cycling and thermal cycling. The mismatch in coefficient of thermal expansion (CTE) between components used in QFN and the non uniform temperature distribution makes the package deform. Modeling of life prediction is usually conducted for Accelerated Thermal Cycling (ATC) condition, which assumes uniform temperature throughout the assembly. An assembly is also subjected to Power Cycling i.e. non uniform temperature with the chip as the only source of heat generation. This work shows the performance of QFN package assembly under thermal and power cycle in combination and the stress distribution and plastic work for the package. The layered model analysis was done to investigate the impact of the FR4 layer and copper content in the PCB on the solder joint reliability. The comparative study between lumped and layered model has also done under power cycling and thermal cycling.", "author_names": [ "Unique Rahangdale", "Rahul Srinivas", "Sumanth Krishnamurthy", "Pavan Rajmane", "Abel Misrak", "A R Nazmus Sakib", "Dereje Agonafer", "Alok Kumar Lohia", "Steven Kummerl", "Luu Nguyen" ], "corpus_id": 33163191, "doc_id": "33163191", "n_citations": 9, "n_key_citations": 1, "score": 0, "title": "Effect of PCB thickness on solder joint reliability of Quad Flat no lead assembly under Power Cycling and Thermal Cycling", "venue": "2017 33rd Thermal Measurement, Modeling Management Symposium (SEMI THERM)", "year": 2017 }, { "abstract": "The combination of mechanochemical method and thermal desorption for remediating polychlorinated biphenyls (PCBs) in contaminated soil was tested in this study. The effects of grinding time and heating time on PCB removal efficiency were investigated. The contaminated soil, mixed with CaO powder at a weight ratio of 1:1, was first ground using a planetary ball mill. After 4 h of grinding, the total PCB concentration and its toxic equivalence quantity (TEQ) decreased by 74.6 and 75.8% respectively. Then, after being heated at 500 degC for 60 min, the residual PCBs in mechanochemical thermal treated soil decreased to 247 ng/g, resulting in a removal efficiency of 99.95% The removal effect can be promoted by longer grinding time and heating time; however, increased energy consumption was inevitable. The combination of grinding time and heating time should be optimized in a practical remediation process.", "author_names": [ "Zhonghua Zhao", "Xiaodong Li", "Ming-jiang Ni", "Tong Chen", "Jian-hua Yan" ], "corpus_id": 22217278, "doc_id": "22217278", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Remediation of PCB contaminated soil using a combination of mechanochemical method and thermal desorption", "venue": "Environmental Science and Pollution Research", "year": 2017 } ]

[ { "abstract": "Provided are: a mold release film which exhibits excellent antistatic effect even in a high temperature environment, while having excellent transparency; and a method for manufacturing a semiconductor package, which uses this mold release film. A mold release film which is arranged on a mold surface that comes into contact with a curable resin during the production of a semiconductor package, wherein a semiconductor element is arranged within a mold and sealed with the curable resin, thereby forming a resin sealed part. This mold release film comprises: a mold releasing base 2 that comes into contact with the curable resin during the formation of the resin sealed part (said base containing no antistatic agent) and an antistatic layer 3 that comes into contact with the mold during the formation of the resin sealed part. The antistatic layer 3 contains at least one antistatic agent selected from the group consisting of conductive polymers and conductive metal oxides. This mold release film has a total light transmittance of 80% or more.", "author_names": [ "Li Jing She", "Ling Mu Zheng Ji" ], "corpus_id": 139723861, "doc_id": "139723861", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Mold release film and method for manufacturing semiconductor package", "venue": "", "year": 2015 }, { "abstract": "Boron Nitride (BN) is used in various applications such as in lubrication, as a releasing agent and also as a thermosetting insulator material and thermal enhancer because of its advanced material properties. Electrophoretic deposition (EPD) method is a new method for semiconductor industries and it has grown in the interest on making use of BN as a thermal interface material and electrical isolation in Transistor Outline (TO) packages. Hexagonal Boron Nitride (h BN) stability in EPD suspension is essential to produce repeatability and reproducibility in the result of the deposition. However, h BN particle has less functional group on its side wall to create bonding with the polymer matrix. In order to increase functional groups on its side wall, NaOH surface treatment which has been established by other researchers was performed. The purpose of this study is to prepare and characterise of the h BN particles in EPD suspension using different types of suspension mediums and binders. The particle size characterization and Field Emission Scanning Electron Microscopy (FESEM) on the as received h BN particle indicates that particle sizes were less than 1 mm but are in agglomerated forms in the De ionized (DI) water suspension. Sedimentation test method of h BN particles in four dispersion media (deionized water, Acetic acid solution, Sulphamic Acid Ammonia) and using different binder (Polyethylene Glycol (PEG) Silane Coupling Agent, Polycationic 1 (PC 1) Polycationic 2 (PC 2) The result showed a combination of deionized water and PC 2 produced the highest stability for h BN dispersion. Sedimentation test and zeta potential method were used to determine the optimum concentration of PC 2 addition in a h BN suspension. EPD of h BN was performed on TO package using different levels of PC 2 concentration (i.e. 0.2 1.0 wt% Characterization of the EPD coating were performed in terms of thickness, microstructure analysis on surface and micrograph from FESEM, and surface roughness. The optimum concentration of PC 2 in order to achieve the highest h BN stability was in the range of 0.3 0.4 wt% with a corresponding deposition thickness of 8 mm. The obtained thickness was the highest among other samples, and had surface roughness of 570 nm. Critical factors that affected the deposition for h BN EPD process were suspension ionic conductivity and excess PC 2 concentration. High conductivity and excess PC 2 concentration caused electric double layer of h BN particles to be compressed thus resulting in a low deposition yield. Therefore, it is recommended that future works use ultra pure DI water and excess binder of h BN suspension need to be removed by centrifugal washing before undergoes EPD to reduce conductivity of h BN suspension. Besides it also helps to achieve a high deposition thickness of h BN for thermal conductive and electrical isolation application.", "author_names": [ "Jayaganasan Narayanasami" ], "corpus_id": 139581658, "doc_id": "139581658", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Preparation Characterization Of Electrophoretically Deposited BN Film For Semiconductor Package", "venue": "", "year": 2017 }, { "abstract": "A preparation method of a special efficient sustained release cold storage agent for supporting fruit and vegetable storage and transportation comprises steps as follows: three raw materials including cyclodextrin, glycerine and sodium polyacrylate are prepared in percentage by weight; under the condition of the room temperature, cyclodextrin is added to water and is stirred until cyclodextrin is sufficiently dissolved to obtain a transparent liquid, and then glycerine is slowly added and stirred until glycerine is sufficiently dissolved; sodium polyacrylate is finally added and stirred until polyacrylate is sufficiently dissolved to obtain a colloidal liquid, and the cold storage agent is obtained; the prepared cold storage agent is packaged. The cold storage agent prepared with the method is non toxic, odorless, safe and environment friendly, has a remarkable refrigeration effect, can be recycled, cannot shrink, and cannot produce deionized water; the preparation process does not require heating, and the operation method is simple and feasible; the sustained release cold storage agent can be recycled, has low cost and good effect, is applicable to large scale production and facilitates popularization.", "author_names": [ "" ], "corpus_id": 140012522, "doc_id": "140012522", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Preparation method of special efficient sustained release cold storage agent for supporting fruit and vegetable storage and transportation", "venue": "", "year": 2015 }, { "abstract": "Back grinding process, to provide a composite function tape for semiconductor package capable of performing a dicing step and a pickup step and the die attach process simultaneously. In particular, the interface between the adhesive layer and the second adhesive layer, by placing the first adhesive layer which is cured with adhesive layer during UV irradiation include a UV curing agent, improved release characteristics of the composite function tape adhesive layer it can be. The semiconductor package multifunction tape according to the present invention, ultraviolet curable adhesive layer formed on one surface of the base film, a first adhesive layer and second adhesive layer formed on the ultraviolet curable pressure sensitive layer provided. .The", "author_names": [ "soku son,kiyu", "bomu chiyun,chiyan", "hiyun chiyo,zie", "ha huwan,yon" ], "corpus_id": 139951895, "doc_id": "139951895", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The method of manufacturing a semiconductor device using the multifunction tape and this semiconductor package", "venue": "", "year": 2009 }, { "abstract": "The academic exploration and technology design of active packaging are coherently supplying innovative approaches for enhancing the quality and safety of food, as well as prolonging their shelf life. With the object of comparison between two barrier materials, such as stable petrochemical polyurethane (PU) (BASF) and biodegradable natural poly(3 hydroxybutyrate) (PHB) (Biomer Co. Krailling, Germany) the study of antibacterial agent release has been performed. For the characterization of polymer surface morphology and crystallinity, the scanning electron microscopy (SEM) atomic force microscopy (AFM) and differential scanning calorimetry (DSC) were used respectively. The antimicrobial activity of chlorhexidine digluconate (CHD) has been estimated by the Bauer Kirby Disk Diffusion Test. It was shown that the kinetic release profiles of CHD, as the active agent, in both polymers, significantly differed due to the superposition of diffusion and surface degradation in poly(3 hydroxybutyrate) (PHB) To emphasize the special transport phenomena in polymer packaging, the diffusivity modeling was performed and the CHD diffusion coefficients for the plane films of PU and PHB were further compared. The benefit of active biodegradable packaging on the base of PHB is discussed.", "author_names": [ "Alexey L Iordanskii", "A L Zhulkina", "Anatoliy Olkhov", "Sergey V Fomin", "Andrey Burkov", "Mikhail Stilman" ], "corpus_id": 91185047, "doc_id": "91185047", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Characterization and Evaluation of Controlled Antimicrobial Release from Petrochemical (PU) and Biodegradable (PHB) Packaging", "venue": "Polymers", "year": 2018 }, { "abstract": "BACKGROUND Recently, antimicrobial photodynamic therapy (aPDT) as an alternative treatment modality has been used adjunctively in the treatment of periodontitis and peri implantitis. Photosensitizing agents in the form of nanoparticles are designed for improving the efficiency of aPTD. Graphene quantum dots are a special type of tiny nanocrystals that can promote aPDT when coupled with curcumin (Cur) The main objective of the present study was to investigate the effects of photoexcited GQD Cur on the metabolic activity of perio pathogen mixed biofilms. MATERIALS AND METHODS GQD Cur was synthesized and characterized by scanning electron microscopy (SEM) dynamic light scattering (DLS) fourier transform infrared (FTIR) spectroscopy, ultraviolet visible spectrometry (UV Vis) and X ray diffraction (XRD) The cell cytotoxicity effect of GQD Cur was evaluated on primary human gingival fibroblast (HuGu) cells. Perio pathogen mixed biofilms including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia photosensitized with GQD doped with Cur were irradiated with a blue LED at a wavelength of 435 20 nm for 1 min, and then bacterial viability measurements were performed. The antimicrobial susceptibility profile, biofilm formation ability, amount of reactive oxygen species (ROS) released, and variations of gene expressions involved in biofilm formation were assessed. RESULTS The SEM, DLS, FTIR, UV Vis spectrometry, and XRD pattern confirmed that GQD Cur was synthesized successfully. According to the results, GQD Cur exhibited no cytotoxicity against HuGu cells. Photoexcited GQD Cur resulted in a significant reduction in cell viability (93% and biofilm formation capacity (76% of peri pathogens compared to the control group (P 0.05) According to the results, a significant concentration dependent increase in the ROS generation was observed in perio pathogens mixed cells treated with different doses of GQD Cur aPDT. Moreover, rcpA, fimA, and inpA gene expression profiles were downregulated by 8.1 9.6 and 11.8 folds, respectively. CONCLUSIONS Based on the results, photoexcited GQD Cur with a high potency of perio pathogens suppression in planktonic and biofilm forms and downregulation of the biofilm genes expression pattern was exploited as a nanoscale based platform for periodontitis.", "author_names": [ "Maryam Pourhajibagher", "Steven J Parker", "Nasim Chiniforush", "Abbas Bahador" ], "corpus_id": 201831950, "doc_id": "201831950", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Photoexcitation triggering via semiconductor graphene quantum dots by photochemical doping with curcumin versus perio pathogens mixed biofilms.", "venue": "Photodiagnosis and photodynamic therapy", "year": 2019 }, { "abstract": "Aroma compounds are known to be efficient active agents for a broad range of applications (antimicrobial, anti oxidant, insect repellent. that are highly sought when aiming at extending shelf life of food or biological products. However, they are intrinsically odorant and volatile at ambient temperature, which restricts the processing routes used to introduce them in a polymeric matrix and can affect their mode of action and limit efficiency. Indeed, due to their high sensitivity toward temperature they can be lost or transformed during processing. Acting after being released in the headspace, their concentration has to be controlled to avoid any odorant contamination of the targeted products. Hence, the ability for an aroma compound to be retained in a polymeric matrix, and then released when submitted to a triggering effect, are the two main requirements that should be satisfied. The volatile nature of the aroma compound offer the possibility when introduce in the packaging to act by direct or indirect contact with the product and thus to be used in different ways; as a coating layer directly applied on the product surface, as a self supported film or as coated paper when associated with a paper sheet, as well as an object that could be inserted in the package. As biopolymers such as proteins and polysaccharides are able to retain aroma compounds but also to favor their release by modification of their structure when the relative humidity (RH) and temperature change, they are relevant carriers of these specific aroma compounds. Examples of how active packaging systems with limonene, eugenol and carvacrol as active agents were designed and elaborated. These examples will be presented with a special focus on the processing conditions and the way to improve their aroma compound retention and the release control (biopolymer nature, cyclodextrin clay addition. Avrami's equation has been used to model the transfer of aroma compound and to advantageously compare it taking into account the mechanism in relation to the biopolymer structural changes.", "author_names": [ "Jose Daniel Wicochea-Rodriguez", "Pascale Chalier", "Thierry Ruiz", "Emmanuelle Gastaldi" ], "corpus_id": 173992565, "doc_id": "173992565", "n_citations": 18, "n_key_citations": 0, "score": 0, "title": "Active Food Packaging Based on Biopolymers and Aroma Compounds: How to Design and Control the Release", "venue": "Front. Chem.", "year": 2019 }, { "abstract": "We have recently implemented a new version of the quasiparticle self consistent GW (QSGW) method in the ecalj package released at this http URL. Since the new version of the ecalj is numerically stable and accurate compared to the previous versions, we can perform calculations easily without being bothered with setting input parameters. Here we examine its ability to describe energy band properties, e.g. band gap energy, eigenvalues at special points and effective mass, for variety of semiconductors and insulators. We treat C, Si, Ge, Sn, SiC (in 2H, 3C, and 4H structures) (Al, Ga, N)x(N, P, As, Pb) (Zn, Cd, Mg)x(O, S, Se, Te) SiO2, HfO2, ZrO2, SrTiO3, PbS, PbTe, MnO, NiO, and HgO. We propose that a hybrid QSGW method, where we mix 80 percent of QSGW and 20 percent of LDA, gives universally good agreement with experiments for these materials.", "author_names": [ "Daiki Deguchi", "Kazunori Sato", "Hiori Kino", "Takao Kotani" ], "corpus_id": 119240717, "doc_id": "119240717", "n_citations": 32, "n_key_citations": 0, "score": 0, "title": "Accurate energy bands calculated by the hybrid quasiparticle self consistent GW method implemented in the ecalj package", "venue": "", "year": 2015 }, { "abstract": "In order to deliver a bioactive agent to a physiological location, it is important to be able to regulate precisely the location and the dosage. Such exquisite control can easily be envisioned for a photochemical drug that is active toward release of the desired bioactive agent upon irradiation of a specific tissue site. These materials should be thermally stable but reactive under excitation at visible (vis) or near infrared (NIR) wavelengths where tissue transmission is optimal. Two photon excitation (TPE) is of special interest, since the use of focused laser pulses to activate release could provide 3D spatial control in therapeutic applications. This Account describes the preparation and photochemistry of a series of transition metal complexes designed to release the simple bioregulatory compound nitric oxide upon vis or NIR excitation. In order to enhance the light gathering capability of such compounds, we have attached chromophores with high single or two photon absorption cross sections to several photochemical NO precursors. For example, the iron nitrosyl clusters Fe2(mu SR)2(NO)4 (Roussin's red esters) have been prepared with various chromophores as pendant groups, an example being the protoporphyrin XI derivative illustrated here. Direct excitation into the vis absorbing Q bands of the porphyrin leads to enhanced rates of NO generation from the Fe/S/NO cluster owing to the larger rate of light absorption by that antenna. Furthermore, femtosecond pulsed laser NIR excitation of the same compound at 810 nm (a spectral region where no absorption bands are apparent) leads to weak emission at approximately 630 nm and generation of NO, both effects providing evidence of a TPE mechanism. Roussin's red esters with other chromophores described here are even more effective for TPE stimulated NO release. Another photochemical NO precursor discussed is the Cr(III) complex trans Cr(L)(ONO)2( where L is a cyclic tetraamine such as cyclam. When L includes a chromophore tethered to the ligand backbone, excitation of that functionality results in energy transfer to the spin forbidden ligand field double states and light stimulated release of NO. We are working to develop systems where L is attached to a semiconductor nanoparticle as the antenna. In this context, we have shown that electrostatic assemblies are formed between the anionic surface of water soluble CdSe/ZnS core/shell quantum dots (QDs) and Cr(L)(ONO)2( cations via an ion pairing mechanism. Photoexcition of such modified QDs leads to markedly enhanced NO generation and suggests promising applications of such nanomaterials as photochemical drugs.", "author_names": [ "Peter C Ford" ], "corpus_id": 29668211, "doc_id": "29668211", "n_citations": 178, "n_key_citations": 0, "score": 1, "title": "Polychromophoric metal complexes for generating the bioregulatory agent nitric oxide by single and two photon excitation.", "venue": "Accounts of chemical research", "year": 2008 }, { "abstract": "The dynamics of nuclear envelope has a critical role in multiple cellular processes. However, little is known regarding the structural changes occurring inside the nucleus or at the inner and outer nuclear membranes. For viruses assembling inside the nucleus, remodeling of the intranuclear membrane plays an important role in the process of virion assembly. Here, we monitored the changes associated with viral infection in the case of nudiviruses. Our data revealed dramatic membrane remodeling inside the nuclear compartment during infection with Oryctes rhinoceros nudivirus, an important biocontrol agent against coconut rhinoceros beetle, a devastating pest for coconut and oil palm trees. Based on these findings, we propose a model for nudivirus assembly in which nuclear packaging occurs in fully enveloped virions. ABSTRACT Enveloped viruses hijack cellular membranes in order to provide the necessary material for virion assembly. In particular, viruses that replicate and assemble inside the nucleus have developed special approaches to modify the nuclear landscape for their advantage. We used electron microscopy to investigate cellular changes occurring during nudivirus infection and we characterized a unique mechanism for assembly, packaging, and transport of new virions across the nuclear membrane and through the cytoplasm. Our three dimensional reconstructions describe the complex remodeling of the nuclear membrane necessary to release vesicle associated viruses into the cytoplasm. This is the first report of nuclear morphological reconfigurations that occur during nudiviral infection. IMPORTANCE The dynamics of nuclear envelope has a critical role in multiple cellular processes. However, little is known regarding the structural changes occurring inside the nucleus or at the inner and outer nuclear membranes. For viruses assembling inside the nucleus, remodeling of the intranuclear membrane plays an important role in the process of virion assembly. Here, we monitored the changes associated with viral infection in the case of nudiviruses. Our data revealed dramatic membrane remodeling inside the nuclear compartment during infection with Oryctes rhinoceros nudivirus, an important biocontrol agent against coconut rhinoceros beetle, a devastating pest for coconut and oil palm trees. Based on these findings, we propose a model for nudivirus assembly in which nuclear packaging occurs in fully enveloped virions.", "author_names": [ "Sailakshmi Velamoor", "Allan Mitchell", "Bruno M Humbel", "Won-mo Kim", "Charlotte Pushparajan", "Gabriel A Visnovsky", "Laura N Burga", "Mihnea Bostina" ], "corpus_id": 221124823, "doc_id": "221124823", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Visualizing Nudivirus Assembly and Egress", "venue": "mBio", "year": 2020 } ]

[ { "abstract": "Abstract The brittle to ductile transition (BDT) is difficult to predict without extensive fitting parameters or tuning to a particular material. Currently, predicting fracture through extensive fitting or computationally expensive algorithms is high in both cost and time required to capture the relevant deformation physics. Presented here is analysis using a comparatively high throughput analytical model to predict fracture behavior using relatively few key experimentally determined parameters: activation volume, shear stress, and activation energy. This approach could reduce the time scale to predict fracture and thus accelerate new materials discovery. The current work utilizes seminal studies to provide the inputs for validating our approach via two single crystal materials, Si and W, which both have marginal toughness at low temperatures. It is shown that knowledge of underlying deformation mechanisms (still in progress) coupled to rapid determination of physical quantities (shear stress, activation volumes, and dislocation shielding) promotes unique discovery and opportunities, including future application to polycrystalline materials and phenomena. The technique, using literature values for physical parameters, correlates well to experimental fracture behavior for these two different classes of materials, semiconductors and metals, offering new opportunities for broader study.", "author_names": [ "William W Gerberich", "Kevin M Schmalbach", "Youxing Chen", "Eric Hintsala", "Nathan A Mara" ], "corpus_id": 234026136, "doc_id": "234026136", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Quantifying physical parameters to predict brittle/ ductile behavior", "venue": "Materials Science and Engineering: A", "year": 2021 }, { "abstract": "Abstract Two German ferritic pressure vessel steels are examined in the brittle to ductile transition regime as a function of temperature and irradiation. The experiments are done by a miniaturized Small Punch Test in hot cells within the temperature range of 185 degC up to 70 degC. From the load displacement curve of the SPT, the yield curves and parameters of both a non local G urson T vergaard N eedleman ductile damage model and a modified B eremin model are identified. The influence of temperature and irradiation on the model parameters is analyzed. All parameters are verified by comparison with results from standard test methods. The parameters, identified from SPT, are used to simulate the failure behavior in standard fracture mechanics specimens. In the upper shelf, the non local GTN model is applied to simulate crack resistance curves, from where the fracture toughness data could be successfully predicted. In the lower shelf, the W eibull stress of the specimens was computed to find out the statistics of fracture toughness values. Finally, the modified B eremin model and the non local ductile damage model were combined to evaluate the failure of fracture specimens in the brittle ductile transition region. This way, an acceptable agreement with Master curve data for non irradiated steels could be achieved in the whole temperature range.", "author_names": [ "Thomas Linse", "Meinhard Kuna", "H W Viehrig" ], "corpus_id": 136699955, "doc_id": "136699955", "n_citations": 18, "n_key_citations": 0, "score": 0, "title": "Quantification of brittle ductile failure behavior of ferritic reactor pressure vessel steels using the Small Punch Test and micromechanical damage models", "venue": "", "year": 2014 }, { "abstract": "A broad classification of solids in terms of their mechanical behavior would characterize them as brittle or ductile. While there is no doubt that ultimately this behavior is due to processes at the atomistic level, the link between these processes and their macroscopic manifestation is difficult to establish. Phenomenological theories that try to address this link must rely on microscopic parameters, the values of which are beyond their scope. Here we review recent efforts to employ first principles electronic structure calculations in order to determine important physical quantities which, in conjunction with phenomenological theories, can provide insight into brittle versus ductile behavior. We apply this approach to cases of intrinsic interest, such as silicon, the prototypical brittle solid, as well as in cases of practical interest, such as the improvement of ductility in molybdenum disilicide, a material of potential usefulness in improved turbine blades. Current indications are that this combination of techniques can serve as powerful qualitative predictive tool for the dependence of mechanical behavior on the microscopic structure and chemical composition of a solid.", "author_names": [ "Umesh V Waghmare", "Efthimios Kaxiras", "Michael S Duesbery" ], "corpus_id": 123624441, "doc_id": "123624441", "n_citations": 38, "n_key_citations": 1, "score": 0, "title": "Modeling Brittle and Ductile Behavior of Solids from First Principles Calculations", "venue": "", "year": 2000 }, { "abstract": "Radiation effects lead to significant reduction in ductility during the life of the components used in nuclear reactors. Sharp change in fracture toughness at lower temperature in Body Centered Cubic (BCC) materials as compared to Face Centered Cubic (FCC) materials is a major concern restricting their application in nuclear reactors in spite of having better thermal properties, excellent resistance to helium embrittlement and void swelling under higher dpa levels. In the present paper such strong temperature dependence of strain rate and flow stress in BCC materials is investigated numerically for both non irradiated and irradiated conditions. The BCC materials subjected to radiation would undergo embrittlement which raises the ductile to brittle transition (DBT) temperature up to or above the room temperature. In view of dislocations mobility being a fundamental property to determine the plastic behavior, a dislocations based material model is proposed which has a physical rather than phenomenological basis. This material model accounts for both thermally activated and athermal regime dislocation mobilities in BCC materials and is capable of predicting the effect of irradiation induced defects on the mobility of the dislocations which in turn directly affect the behavior of such materials. The relative change in stress field due to presence of irradiation defects in comparison to non irradiated case provides a valuable input for brittle fracture model to develop advanced materials for nuclear application.", "author_names": [ "Kulbir Singh", "Christian Robertson", "Arun Kumar Bhaduri" ], "corpus_id": 202969013, "doc_id": "202969013", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Brittle Fracture Model Parameter Estimation for Irradiated BCC Material through Dislocation Based Crystal Plasticity Model", "venue": "Frattura ed Integrita Strutturale", "year": 2019 }, { "abstract": "Fracture properties of Reactor Pressure Vessel (RPV) steels show large variations with changes in temperature and irradiation levels. Brittle behavior is observed at lower temperatures and/or higher irradiation levels whereas ductile mode of failure is predominant at higher temperatures and/or lower irradiation levels. In addition to such temperature and radiation dependent fracture behavior, significant scatter in fracture toughness has also been observed. As a consequence of such variability in fracture behavior, accurate estimates of fracture properties of RPV steels are of utmost importance for safe and reliable operation of reactor pressure vessels.A cohesive zone based approach is being pursued in the present study where an attempt is made to obtain a unified law capturing both stable crack growth (ductile fracture) and unstable failure (cleavage fracture) The parameters of the constitutive model are dependent on both temperature and failure probability. The effect of irradiation has not been considered in the present study. The use of such a cohesive zone based approach would allow the modeling of explicit crack growth at both stable and unstable regimes of fracture. Also it would provide the possibility to incorporate more physical lower length scale models to predict DBT. Such a multi scale approach would significantly improve the predictive capabilities of the model, which is still largely empirical.Copyright (c) 2013 by ASME", "author_names": [ "Pritam Kishore Chakraborty", "Suleyman Bulent Biner" ], "corpus_id": 136863993, "doc_id": "136863993", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Modeling the Ductile Brittle Fracture Transition in Reactor Pressure Vessel Steels Using a Cohesive Zone Model Based Approach", "venue": "", "year": 2013 }, { "abstract": "Both scientists and engineers are very much concerned with the study of ductile to brittle transition (DBT) in ferritic steels. For historical reasons the Charpy impact test remains widely used in the industry as a quality control tool to determine the DBT temperature. The transition between the two failure modes, i.e. brittle cleavage at low temperature and ductile fracture at the upper shelf occurs also at low loading rate in fracture toughness tests. Recent developments have been made in the understanding of the micromechanisms controlling either cleavage fracture in BCC metals or ductile rupture by cavity nucleation, growth and coalescence. Other developments have also been made in numerical tools such as the finite element (FE) method incorporating sophisticated constitutive equations and damage laws to simulate ductile crack growth (DCG) and cleavage fracture. Both types of development have thus largely contributed to modeling DBT occurring either in impact tests or in fracture toughness tests. This constitutes the basis of a modern methodology to investigate fracture, which is the so called local approach to fracture. In this study the micromechanisms of brittle cleavage fracture and ductile rupture are firstly shortly reviewed. Then the transition between both modes of failure is investigated. It is shown that the DBT behavior observed in impact tests or in fracture toughness specimens can be reasonably well predicted using modern theories on brittle and ductile fracture in conjunction with FE numerical simulations. The review includes a detailed study of a number of metallurgical parameters contributing to the variation of the DBT temperature. Two main types of steels are considered (i) quenched and tempered bainitic and martensitic steels used in the fabrication of pressurized water reactors, and (ii) modern high toughness line pipe steels obtained by chemical variations and optimized hot rolling conditions. An attempt is also made to underline the research areas which remain to be explored for improving the strength toughness compromise in the development of steels.", "author_names": [ "Andre Pineau" ], "corpus_id": 136778709, "doc_id": "136778709", "n_citations": 60, "n_key_citations": 2, "score": 0, "title": "Modeling ductile to brittle fracture transition in steels micromechanical and physical challenges", "venue": "", "year": 2008 }, { "abstract": "In the context of the third Sandia Fracture Challenge (SFC3) the details of the blind predictions performed by the University of Texas team are provided in this article. Over the past two decades, the peridynamic theory has shown great promise in modeling autonomous crack nucleation and growth in materials. While peridynamics has been commonly applied to simulate failure of brittle materials, its ability in predicting ductile fracture has remained mostly untested. This fracture challenge was seen as an opportunity to assess the state of the art of the peridynamic theory in predicting the response of an additively manufactured 316L stainless steel bar with a complex geometry under the dynamic tensile experiments performed by Sandia National Laboratories. The performance of a recently proposed, generalized, ordinary finite deformation constitutive correspondence model, coupled with a recent state based damage correspondence model was explored over this problem. For finite deformation material modeling, the classical elastoplastic framework of Simo was implemented within the ordinary correspondence theory. Damage modeling was achieved by incorporating the Johnson Cook failure criterion using the damage correspondence framework. An iterative inverse technique was applied to calibrate the model parameters using the longitudinal and notched tensile tests data provided by Sandia National Laboratories. A blind prediction of the deformation and failure behavior of the SFC3 geometry was performed by embedding the calibrated model in a peridynamic simulation. Uncertainty was introduced into the model parameters to quantify material variability. The results are compared to the experiments conducted at Sandia National Laboratories. While our modeling approach led to qualitatively good results and a correctly predicted crack path, it underpredicted the load carrying capacity of the structure and simulated an early fracture. Our post experiment analysis identifies material instability issues associated with the model as the primary sources of error.", "author_names": [ "Masoud Behzadinasab", "John T Foster" ], "corpus_id": 198177903, "doc_id": "198177903", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "The third Sandia Fracture Challenge: peridynamic blind prediction of ductile fracture characterization in additively manufactured metal", "venue": "International Journal of Fracture", "year": 2019 }, { "abstract": "Abstract The structural, mechanical, and electronic properties of perovskite molybdates are a topic of frequent study in materials science. In this study, the influence of Mg doping on the physical metallurgy of perovskite molybdates is investigated using first principles calculations based on density functional theory (DFT) and molecular dynamics (MD) simulation. Our calculated optimized lattice parameters (3.9945, 3.8964, 3.8634, 3.8440, and 3.7952 A [mentioned only DFT data, MD data listed in Table 2 for x 0, 0.1, 0.2, 0.3, and 0.4 respectively) of SrMo1 xMgxO3 are highly consistent with other experimental results (3.9762, 3.9695, and 3.9649 A for x 0, 0.1, and 0.2 respectively) and some available theoretical results (3.9720 A for x 0, no previous data available for Mg doped systems) The calculated elastic constants satisfied the Born stability criteria, indicating that our studied materials are mechanically stable at all doping concentrations, which was also confirmed by the calculated negative values of Cohesive energy. The mechanical behaviors of perovskite, including elastic constants, elastic moduli, ductility, and elastic anisotropy, were investigated and discussed. Our computed results suggest that Mg doping can increase elastic moduli. The calculated Pugh's ratio increased from 0.42 to 0.71 [DFT] and from 0.47 to 0.75 [MD] as well as the Poisson's ratio decreased from 0.31 to 0.21 [DFT] and from 0.30 to 0.21 [MD] which transformed the compound from ductile to brittle due to the addition of Mg at Mo site. The band structures, density of states, and charge density redistributions of the undoped and Mg doped materials were predicted. Our simulation outputs clearly illustrated the importance of accounting for Mg doping's influence in theoretical simulations of the physical properties of the presently studied perovskite material.", "author_names": [ "Khandaker Monower Hossain", "M Zahid Hasan", "Md Lokman Ali" ], "corpus_id": 225195819, "doc_id": "225195819", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Understanding the influences of Mg doping on the physical properties of SrMoO3 perovskite", "venue": "", "year": 2020 }, { "abstract": "Fused depositional modeling (FDM) is one of the common methods for 3D printing of polymers, which is expanding in various industrial applications, scientific researches, and engineering applications due to its ability to make complex parts. In this research, molecular dynamics (MDs) simulation has been used to predict the physical and mechanical properties. Then, the mechanical properties of the printed parts were determined. The mechanical properties of 3D printed parts strongly depend on the correct selection of processing parameters. In this study, the effect of three important parameters such as infill density, printing speed, and layer thickness were investigated on the tensile properties of PLA specimens. For this purpose, standard specimens with four infill densities of 20% 40% 60% and 80% two speeds of 20 mm/s and 40 mm/s, and two thicknesses of 0.1 mm and 0.2 mm were printed and tested under quasi static tensile test. In all printed specimens, the print angle is 45deg. The obtained experimental outcomes from the tensile test revealed that with increasing the infilling density, the mechanical properties of the parts improve and increase significantly. However, at very high infilling densities, the samples behave more brittle, so in cases where the strength of the part is less important than its shape and appearance, a density of 40% is more suitable in terms of cost, material, and time savings. It was also noted that the printing speed has less effect on the mechanical properties of PLA parts. It was also observed that reducing the thickness of the layer, while slightly increasing the stiffness of the parts, makes the part extremely brittle, and on the other hand, it leads to increase in the dimensional accuracy and surface quality of the specimens. At infill density of 80% the specimens had the highest stiffness and strength, but it exhibits a brittle behavior. Moreover, it can be deduced that by reducing the layer thickness although the modulus of elasticity increases a little, ductility is greatly affected.", "author_names": [ "Ashkan Farazin", "Mehdi Mohammadimehr" ], "corpus_id": 236399262, "doc_id": "236399262", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Effect of different parameters on the tensile properties of printed Polylactic acid samples by FDM: experimental design tested with MDs simulation", "venue": "", "year": 2021 }, { "abstract": "Abstract The size dependent brittle to ductile transition of silicon has been observed with nanowire structures in experiments and many research efforts have focused on revealing its underlying physical mechanisms through both experimental and simulation approaches. While most simulation studies using molecular dynamics have considered the influence of various factors such as strain rate, temperature, and size, etc. little is known about the effect of boundary conditions and simulation types, i.e. constant energy vs. constant temperature simulations. In this work, we study the effects of boundary conditions and thermostats on the failure behavior of silicon nanowires by performing the molecular dynamics simulation of the uniaxial tensile test with three modified embedded atom method potentials. The nanowires are subjected to either periodic boundary conditions or fixed end boundary conditions and the simulation is conducted under either the constant energy or constant temperature conditions by Langevin thermostat. The simulations reveal that Young's modulus and tensile strength exhibit little dependence on the boundary condition and thermostat while the failure strain of the nanowires increases with fixed boundary conditions compared to the nanowires subjected to periodic boundary conditions. The failure behaviors, which are quantified by our novel ductility failure probability parameter, exhibit larger, but limited variations depending on the boundary condition, but the trend is mixed and not conclusive.", "author_names": [ "Wen-ting Xu", "Woo kyun Kim" ], "corpus_id": 216476038, "doc_id": "216476038", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Role of boundary conditions and thermostats in the uniaxial tensile loading of silicon nanowires", "venue": "", "year": 2020 } ]

[ { "abstract": "The ever increasing processing power demands of digital computers cannot continue to be fulfilled indefinitely unless there is a paradigm shift in computing. Neuromorphic computing, which takes inspiration from the highly parallel, low power, high speed, and noise tolerant computing capabilities of the brain, may provide such a shift. Many researchers from across academia and industry have been studying materials, devices, circuits, and systems, to implement some of the functions of networks of neurons and synapses to develop neuromorphic computing platforms. These platforms are being designed using various hardware technologies, including the well established complementary metal oxide semiconductor (CMOS) and emerging memristive technologies such as SiOx based memristors. Herein, recent progress in CMOS, SiOx based memristive, and mixed CMOS memristive hardware for neuromorphic systems is highlighted. New and published results from various devices are provided that are developed to replicate selected functions of neurons, synapses, and simple spiking networks. It is shown that the CMOS and memristive devices are assembled in different neuromorphic learning platforms to perform simple cognitive tasks such as classification of spike rate based patterns or handwritten digits. Herein, it is envisioned that what is demonstrated is useful to the unconventional computing research community by providing insights into advances in neuromorphic hardware technologies.", "author_names": [ "Mostafa Rahimi Azghadi", "Ying-Chen Chen", "Jason Kamran Eshraghian", "Jia Chen", "Chih-Yang Lin", "Amirali Amirsoleimani", "Adnan Mehonic", "Anthony J Kenyon", "Burt W Fowler", "Jack C Lee", "Yao-Feng Chang" ], "corpus_id": 221421740, "doc_id": "221421740", "n_citations": 35, "n_key_citations": 0, "score": 1, "title": "Complementary Metal Oxide Semiconductor and Memristive Hardware for Neuromorphic Computing", "venue": "Advanced Intelligent Systems", "year": 2020 }, { "abstract": "The continued growth in the demand of data storage and processing has spurred the development of high performance storage technologies and brain inspired neuromorphic hardware. Semiconductor quantum dots (QDs) offer an appealing option for these applications since they combine excellent electronic/optical properties and structural stability and can address the requirements of low cost, large area, and solution based manufactured technologies. Here, we focus on the development of nonvolatile memories and neuromorphic computing systems based on QD thin film solids. We introduce recent advances of QDs and highlight their unique electrical and optical features for designing future electronic devices. We also discuss the advantageous traits of QDs for novel and optimized memory techniques in both conventional flash memories and emerging memristors. Then, we review recent advances in QD based neuromorphic devices from artificial synapses to light sensory synaptic platforms. Finally, we highlight major challenges for commercial translation and consider future directions for the postsilicon era.", "author_names": [ "Ziyu Lv", "Jingrui Chen", "Junjie Wang", "Ye Zhou", "Su-Ting Han" ], "corpus_id": 214616983, "doc_id": "214616983", "n_citations": 53, "n_key_citations": 0, "score": 0, "title": "Semiconductor Quantum Dots for Memories and Neuromorphic Computing Systems.", "venue": "Chemical reviews", "year": 2020 }, { "abstract": "As artificial intelligence calls for novel energy efficient hardware, neuromorphic computing systems based on analog resistive switching memory (RSM) devices have drawn great attention recently. Different from the well studied binary RSMs, the analog RSMs are featured by a continuous and controllable conductance tuning ability and thus are capable of combining analog computing and data storage at the device level. Although significant research achievements on analog RSMs have been accomplished, there have been few works demonstrating large scale neuromorphic systems. A major bottleneck lies in the reliability issues of the analog RSM, such as endurance and retention degradation and read/write noises and disturbances. Owing to the complexity of resistive switching mechanisms, studies on the origins of reliability degradation and the corresponding optimization methodology face many challenges. In this article, aiming on the high performance neuromorphic computing applications, we provide a comprehensive review on the status of reliability studies of analog RSMs, the reliability requirements, and evaluation criteria and outlook for future reliability research directions in this field.", "author_names": [ "Meiran Zhao", "Bin Gao", "Jianshi Tang", "He Qian", "Huaqiang Wu" ], "corpus_id": 213860172, "doc_id": "213860172", "n_citations": 57, "n_key_citations": 0, "score": 0, "title": "Reliability of analog resistive switching memory for neuromorphic computing", "venue": "", "year": 2020 }, { "abstract": "Functional emulation of biological synapses using electronic devices is regarded as the first step toward neuromorphic engineering and artificial neural networks (ANNs) Electrolyte gated transistors (EGTs) are mixed ionic electronic conductivity devices capable of efficient gate channel capacitance coupling, biocompatibility, and flexible architectures. Electrolyte gating offers significant advantages for the realization of neuromorphic devices/architectures, including ultralow voltage operation and the ability to form parallel interconnected networks with minimal hardwired connectivity. In this review, the most recent developments in EGT based electronics are introduced with their synaptic behaviors and detailed mechanisms, including short /long term plasticity, global regulation phenomena, lateral coupling between device terminals, and spatiotemporal correlated functions. Analog memory phenomena allow for the implementation of perceptron based ANNs. Due to their mixed conductivity phenomena, neuromorphic circuits based on EGTs allow for facile interfacing with biological environments. We also discuss the future challenges in implementing low power, high speed, and reliable neuromorphic computing for large scale ANNs with these neuromorphic devices. The advancement of neuromorphic devices that rely on EGTs highlights the importance of this field for neuromorphic computing and for novel healthcare technologies in the form of adaptable or trainable biointerfacing.", "author_names": [ "Haifeng Ling", "Dimitrios A Koutsouras", "Setareh Kazemzadeh", "Yoeri van de Burgt", "Feng Yan", "Paschalis Gkoupidenis" ], "corpus_id": 212754746, "doc_id": "212754746", "n_citations": 42, "n_key_citations": 0, "score": 0, "title": "Electrolyte gated transistors for synaptic electronics, neuromorphic computing, and adaptable biointerfacing", "venue": "", "year": 2020 }, { "abstract": "Guided by brain like 'spiking' computational frameworks, neuromorphic computing brain inspired computing for machine intelligence promises to realize artificial intelligence while reducing the energy requirements of computing platforms. This interdisciplinary field began with the implementation of silicon circuits for biological neural routines, but has evolved to encompass the hardware implementation of algorithms with spike based encoding and event driven representations. Here we provide an overview of the developments in neuromorphic computing for both algorithms and hardware and highlight the fundamentals of learning and hardware frameworks. We discuss the main challenges and the future prospects of neuromorphic computing, with emphasis on algorithm hardware codesign. The authors review the advantages and future prospects of neuromorphic computing, a multidisciplinary engineering concept for energy efficient artificial intelligence with brain inspired functionality.", "author_names": [ "Kaushik Roy", "Akhilesh Jaiswal", "Priyadarshini Panda" ], "corpus_id": 208329736, "doc_id": "208329736", "n_citations": 230, "n_key_citations": 9, "score": 0, "title": "Towards spike based machine intelligence with neuromorphic computing", "venue": "Nature", "year": 2019 }, { "abstract": "Neuromorphic computing takes inspiration from the brain to create energy efficient hardware for information processing, capable of highly sophisticated tasks. Systems built with standard electronics achieve gains in speed and energy by mimicking the distributed topology of the brain. Scaling up such systems and improving their energy usage, speed and performance by several orders of magnitude requires a revolution in hardware. We discuss how including more physics in the algorithms and nanoscale materials used for data processing could have a major impact in the field of neuromorphic computing. We review striking results that leverage physics to enhance the computing capabilities of artificial neural networks, using resistive switching materials, photonics, spintronics and other technologies. We discuss the paths that could lead these approaches to maturity, towards low power, miniaturized chips that could infer and learn in real time. Neuromorphic computing takes inspiration from the brain to create energy efficient hardware for information processing, capable of highly sophisticated tasks. Including more physics in the algorithms and nanoscale materials used for computing could have a major impact in this field.", "author_names": [ "Danijela Markovic", "Alice Mizrahi", "Damien Querlioz", "Julie Grollier" ], "corpus_id": 212644549, "doc_id": "212644549", "n_citations": 55, "n_key_citations": 1, "score": 0, "title": "Physics for neuromorphic computing", "venue": "ArXiv", "year": 2020 }, { "abstract": "Abstract Neuromorphic networks that consist of electronic synapses are very important for energy efficient artificial intelligent applications. Therefore, in recent years, many efforts have been made to design and improve artificial synaptic devices to effectively mimic brain spiking activity in biological synapses. In this work, we demonstrate a novel synaptic transistor based on the VO2 film that uses the electrolyte gating at room temperature. Through the gating induced protonation and deprotonation, we realize reversible phase transformations between various H doped phases, which is confirmed by many characterization measurements. The VO2 synaptic transistor based on the exploiting nonvolatile multi level conductance states with various hydrogen doping concentrations can successfully emulate essential synaptic functions such as synaptic plasticity and spiking time dependent plasticity. An artificial neural network containing the VO2 synaptic transistors simulated with supervised learning shows high recognition accuracy for the MNIST handwritten recognition dataset. This study provides a promising approach to develop high performance electronic synaptic transistors by utilizing advanced Mott materials.", "author_names": [ "Chen Ge", "Ge Li", "Qingli Zhou", "Jian-yu Du", "Er-Jia Guo", "Meng He", "Can Wang", "Guo-zhen Yang", "Kuijuan Jin" ], "corpus_id": 210230342, "doc_id": "210230342", "n_citations": 20, "n_key_citations": 0, "score": 0, "title": "Gating induced reversible HxVO2 phase transformations for neuromorphic computing", "venue": "", "year": 2020 }, { "abstract": "Ionic floating gate memories Digital implementations of artificial neural networks perform many tasks, such as image recognition and language processing, but are too energy intensive for many applications. Analog circuits that use large crossbar arrays of synaptic memory elements represent a low power alternative, but most devices cannot update the synaptic weights uniformly or scale to large array sizes. Fuller et al. developed an integrated device, ionic floating gate memory, that has the gate terminal of a redox transistor electrically connected to a diffusive memristor. This low power device enabled linear and symmetric weight updates in parallel over an entire crossbar array at megahertz rates over 109 write read cycles. Science, this issue p. 570 A low power artificial neural network is enabled by crossbar arrays of redox transistor memories and diffusive memristors. Neuromorphic computers could overcome efficiency bottlenecks inherent to conventional computing through parallel programming and readout of artificial neural network weights in a crossbar memory array. However, selective and linear weight updates and <10 nanoampere read currents are required for learning that surpasses conventional computing efficiency. We introduce an ionic floating gate memory array based on a polymer redox transistor connected to a conductive bridge memory (CBM) Selective and linear programming of a redox transistor array is executed in parallel by overcoming the bridging threshold voltage of the CBMs. Synaptic weight readout with currents <10 nanoamperes is achieved by diluting the conductive polymer with an insulator to decrease the conductance. The redox transistors endure >1 billion write read operations and support >1 megahertz write read frequencies.", "author_names": [ "Elliot J Fuller", "Scott Tom Keene", "Armantas Melianas", "Zhongrui Wang", "Sapan Agarwal", "Yiyang Li", "Yaakov Tuchman", "Conrad D James", "Matthew J Marinella", "J Joshua Yang", "Alberto Salleo", "A Alec Talin" ], "corpus_id": 133605392, "doc_id": "133605392", "n_citations": 177, "n_key_citations": 0, "score": 0, "title": "Parallel programming of an ionic floating gate memory array for scalable neuromorphic computing", "venue": "Science", "year": 2019 }, { "abstract": "Neuromorphic computing has emerged as one of the most promising paradigms to overcome the limitations of von Neumann architecture of conventional digital processors. The aim of neuromorphic computing is to faithfully reproduce the computing processes in the human brain, thus paralleling its outstanding energy efficiency and compactness. Toward this goal, however, some major challenges have to be faced. Since the brain processes information by high density neural networks with ultra low power consumption, novel device concepts combining high scalability, low power operation, and advanced computing functionality must be developed. This work provides an overview of the most promising device concepts in neuromorphic computing including complementary metal oxide semiconductor (CMOS) and memristive technologies. First, the physics and operation of CMOS based floating gate memory devices in artificial neural networks will be addressed. Then, several memristive concepts will be reviewed and discussed for applications in deep neural network and spiking neural network architectures. Finally, the main technology challenges and perspectives of neuromorphic computing will be discussed.", "author_names": [ "Valerio Milo", "Gerardo Malavena", "Christian Monzio Compagnoni", "Daniele Ielmini" ], "corpus_id": 210042019, "doc_id": "210042019", "n_citations": 23, "n_key_citations": 0, "score": 0, "title": "Memristive and CMOS Devices for Neuromorphic Computing", "venue": "Materials", "year": 2020 }, { "abstract": "A memristor 1 has been proposed as an artificial synapse for emerging neuromorphic computing applications 2 3 To train a neural network in memristor arrays, changes in weight values in the form of device conductance should be distinct and uniform 3 An electrochemical metallization (ECM) memory 4 5 typically based on silicon (Si) has demonstrated a good analogue switching capability 6 7 owing to the high mobility of metal ions in the Si switching medium 8 However, the large stochasticity of the ion movement results in switching variability. Here we demonstrate a Si memristor with alloyed conduction channels that shows a stable and controllable device operation, which enables the large scale implementation of crossbar arrays. The conduction channel is formed by conventional silver (Ag) as a primary mobile metal alloyed with silicidable copper (Cu) that stabilizes switching. In an optimal alloying ratio, Cu effectively regulates the Ag movement, which contributes to a substantial improvement in the spatial/temporal switching uniformity, a stable data retention over a large conductance range and a substantially enhanced programmed symmetry in analogue conductance states. This alloyed memristor allows the fabrication of large scale crossbar arrays that feature a high device yield and accurate analogue programming capability. Thus, our discovery of an alloyed memristor is a key step paving the way beyond von Neumann computing. Alloying conduction channels of a Si memristor enables stable and controllable device operation with high switching uniformity.", "author_names": [ "Hanwool Yeon", "Peng Lin", "Chanyeol Choi", "Scott H Tan", "Yongmo Park", "Doyoon Lee", "Jaeyong Lee", "Feng Xu", "Bin Gao", "Huaqiang Wu", "He Qian", "Yifan Nie", "Seyoung Kim", "Jeehwan Kim" ], "corpus_id": 219543281, "doc_id": "219543281", "n_citations": 27, "n_key_citations": 0, "score": 0, "title": "Alloying conducting channels for reliable neuromorphic computing", "venue": "Nature Nanotechnology", "year": 2020 } ]

[ { "abstract": "Abstract Surface roughness is an important characteristic which affects the quality, performance and lifetime of many types of industrial products, ranging from mechanical and biomedical parts to semiconductors and optics. In recent years, in situ measurement for surface roughness is increasingly demanded to provide real time feedback and reduce systematic errors of realignment and repositioning during manufacturing. Commercially available instruments, such as stylus profilometer, confocal laser scanning microscope and coherence scanning interferometer, are limited to a relatively low measurement speed and difficult for in situ measurement. In this paper, an in house developed surface measuring system using chromatic confocal sensor was integrated into a mass finishing cell to perform in situ and non contact surface roughness measurement. The surface roughness parameters are calculated and evaluated according to ISO 4287 and ISO 4288. From the preliminary experiments, it was verified that the relative error of surface roughness measurements can be kept within 5%", "author_names": [ "Shaowei Fu", "Wei Sheng Kor", "Fang Cheng", "Leong Keey Seah" ], "corpus_id": 226694936, "doc_id": "226694936", "n_citations": 2, "n_key_citations": 0, "score": 1, "title": "In situ measurement of surface roughness using chromatic confocal sensor", "venue": "", "year": 2020 }, { "abstract": "Roughness measurement is of highlighted importance in production for describing the quality control of manufacturing processes for the functional, tribological, etc. properties of the surfaces of parts. In the last 15 years or so the areal roughness studied on topographies has also become more common, as it provides a more accurate and detailed characterization of the surfaces. However, with relatively little experience and different technical conditions, topographies are analyzed differently. Sometimes 3D topography is used only as an illustration; however, spatial roughness measurement can provide much more information. The effect of measurement speed and point density during roughness measurement on the areal roughness was investigated using a confocal chromatic sensor.", "author_names": [ "Antal Nagy" ], "corpus_id": 230538584, "doc_id": "230538584", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "INFLUENCE OF MEASUREMENT SETTINGS ON AREAL ROUGHNESS WITH CONFOCAL CHROMATIC SENSOR ON FACE MILLED SURFACE", "venue": "", "year": 2020 }, { "abstract": "Laser micromachining is a prominent method of fabricating microchannels on a wide range of metals, non metals, and polymers for biomedical, chemical, fuel cell applications for flow of liquids and gases in predefined path for microfluidic systems. In situ measurement of precise geometrical features on fabricated channels is required to avoid systematic errors. The geometrical parameters such as width, depth, aspect ratio of microchannels are the most important attributes which greatly influence quality of microchannels. This paper proposes in situ measurement of fabricated microchannels on EN 31 steel using LMM by integrating confocal sensor with micromachining system. Geometrical features have been measured with confocal sensor which is further employed to evaluate aspect ratio (AR) Obtained results are compared with microscopic images of the samples for geometrical features. Confocal sensor used to measure surface roughness. 3D profilometer is used to analyse MRR (based on measured cross section area) and oxidised zone width surrounded to microchannel.", "author_names": [ "Ashish Kumar Sahu", "Faiz Iqbal", "Aman Kumar", "Sunil Jha" ], "corpus_id": 226845815, "doc_id": "226845815", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "In situ geometric measurement of microchannels on EN31 steel by laser micromachining using confocal sensor", "venue": "", "year": 2019 }, { "abstract": "In this research a confocal chromatic point sensor was implemented in a desktop sized machine tool. The sensor was used to detect the surface in z direction. Data from the machine control of the x and y axes is extracted and combined with the z information of the sensor to directly scan surfaces. With the presented sensor, micro structures as small as 5 mm can be characterized. Based on the possibilities of this measuring system, face milling before the actual micro machining can be avoided by determining tilts and waviness of the workpiece. Also the effective tool diameter can be determined and compensated. After machining, the structure can be measured for quality control. Based on this measurement system, a micro machining process was developed broadening the potential for the use of desktop sized machine tools.", "author_names": [ "Christopher Muller", "Ingo G Reichenbach", "Martin Bohley", "Jan C Aurich" ], "corpus_id": 138326027, "doc_id": "138326027", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "In Situ Topology Measurement of Micro Structured Surfaces with a Confocal Chromatic Sensor on a Desktop Sized Machine Tool", "venue": "", "year": 2016 }, { "abstract": "The characterization of surface topographic features on a component is typically quantified using two dimensional roughness descriptors which are captured by off line desktop instruments. Ideally any measurement system should be integrated into the manufacturing process to provide in situ measurement and real time feedback. A non contact in situ surface topography measuring system is proposed in this paper. The proposed system utilizes a laser confocal sensor in both lateral and vertical scanning modes to measure the height of the target features. The roughness parameters are calculated in the developed data processing software according to ISO 4287. To reduce the inherent disadvantage of confocal microscopy, e.g. scattering noise at steep angles and background noise from specular reflection from the optical elements, the developed system has been calibrated and a linear correction factor has been applied in this study. A particular challenge identified for this work is the in situ measurement of features generated by a robotized surface finishing system. The proposed system was integrated onto a robotic arm with the measuring distance and angle adjusted during measurement based on a CAD model of the component in question. Experimental data confirms the capability of this system to measure the surface roughness within the Ra range of 0.2 7 mm (bandwidth lc/ls of 300) with a relative accuracy of 5%", "author_names": [ "Shaowei Fu", "Fang Cheng", "Tegoeh Tjahjowidodo", "Yu Zhou", "David Butler" ], "corpus_id": 52005370, "doc_id": "52005370", "n_citations": 23, "n_key_citations": 0, "score": 0, "title": "A Non Contact Measuring System for In Situ Surface Characterization Based on Laser Confocal Microscopy", "venue": "Sensors", "year": 2018 }, { "abstract": "Introduction State of the art machining technologies enable the manufacturing of complex optical surfaces as aspheres and freeforms. To ensure the high quality demands of innovative optical surfaces, correction loops are implemented within the manufacturing process. These loops are based on metrology data. To avoid scratches on sensitive surfaces, non contact measurements are preferable. The classical approach of noncontact testing of optical surfaces is interferometry. However, the testing is complex because Computer Generated Holograms (CGH) have to be used to compensate the wave front differences between reference optic and test part [1] The results of these measurements are highly accurate, but not flexible and considerably more expensive, since each surface needs its own CGH. In situ measurements with alternative non contact measurement systems could reduce time and costs of the manufacturing process. Besides, tensions from clamping have no influence on the measurement, because in situ metrology without repositioning the workpiece works.", "author_names": [ "Confocal Sensor", "Ralf Steinkopf", "S Zwick", "Andreas Gebhardt", "Stefan Dr Risse", "Ramona Eberhardt" ], "corpus_id": 220054237, "doc_id": "220054237", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "IN SITU TESTING OF A FREEFORM OPTIC WITH A CHROMATIC", "venue": "", "year": 2013 }, { "abstract": "A chromatic confocal microscope (CCM) is a high dynamic range noncontact distance measurement sensor; it is based on a hyperchromatic lens. The vast majority of commercial CCMs use refractive based chromatic dispersion to chromatically code the optical axis. This approach significantly limits the range of applications and performance of the CCM. In order to be a suitable alternative to a laser triangulation gauge and laser encoder, the performance of the CCM must be improved. In this paper, it is shown how hybrid aspheric diffractive (HAD) lenses can bring the CCM to its full potential by increasing the dynamic range by a factor of 2 and the resolution by a factor of 5 while passively athermizing and increasing the light throughput efficiency of the optical head [M. Rayer, U.S. patent 1122052.2 (2011) The only commercially suitable manufacturing process is single point diamond turning. However, the optical power carried by the diffractive side of a hybrid aspheric diffractive lens is limited by the manufacturing process. A theoretical study of manufacturing losses has revealed that the HAD configuration with the highest diffraction efficiency is for a staircase diffractive surface (SDS) SDS lenses have the potential to reduce light losses associated with manufacturing limits by a factor of 5 without increasing surface roughness, allowing scalar diffraction limited optical design with a diffractive element.", "author_names": [ "Mathieu Rayer", "Daniel Mansfield" ], "corpus_id": 41562689, "doc_id": "41562689", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Chromatic confocal microscopy using staircase diffractive surface.", "venue": "Applied optics", "year": 2014 }, { "abstract": "Evaluation of Surface Roughness is a crucial requirement in analyzing components life and performances. In analyzing Surface finish, Ra, Rz and Rq are the most widely used parameters in terms of 2D roughness and Sa,Sz and Sq with respect to 3D parameters. Assessment of Surface roughness involves various contact and noncontact methods. This work deals with a new surface inspection strategy applying a newly developed MATLAB algorithm for the BEMRF process. Conventionally the finished workpiece is unloaded for inspection thus generating a loss of production time and hindering the automation of the process. This work attempts to minimize the loss of time in frequent inspection of the finished workpiece by using a laser confocal chromatic sensor which is an integral part of the BEMRF setup. The laser confocal sensor measures the data points (i.e. heights of the surface asperities) of the surface there by aiding in surface finish evaluation. The Surface data points are analyzed by the proposed MATLAB algorithms. The MATLAB algorithms evaluated the data points, taking the data points as input and generated 2D parameters (Ra, Rz, Rq) and 3D parameters (Sa, Sq, Sz) as outputs. The results were compared with that of the standard methods of roughness measurement and were found to be marginally superior over them.", "author_names": [ "Radhik Rammohan", "M Omkumar", "Faiz Iqbal" ], "corpus_id": 201685964, "doc_id": "201685964", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Evaluation of 2D and 3D Surface Roughness Parameters by MATLAB Algorithm in Ball End Magnetorheological Finishing Machine", "venue": "", "year": 2017 }, { "abstract": "Chromatic confocal spectral interferometry (CCSI) is a hybrid method for fast topography measurement, which combines the advantages of the interferometric gain and accuracy with the robustness of confocal microscopy. The CCSI principle provides a single shot measurement of depth while offering a higher lateral resolution than commonly used spectral interferometers. This contribution is focused on the modeling and simulation of a CCSI sensor for measuring rough surfaces, based on sequential and non sequential ray tracing. With the simulation, the influence of surface roughness, surface reflectivity, and surface contamination on reliability of the sensor can be estimated.", "author_names": [ "Wolfram Lyda", "David Fleischle", "Tobias Haist", "Wolfgang Osten" ], "corpus_id": 120821316, "doc_id": "120821316", "n_citations": 9, "n_key_citations": 1, "score": 0, "title": "Chromatic confocal spectral interferometry for technical surface characterization", "venue": "Optical Engineering Applications", "year": 2009 }, { "abstract": "Both contact and non contact probes are often used in dimensional metrology applications, especially for roughness, form and surface profile measurements. To perform such kind of measurements with a nanometer level of accuracy, LNE (French National Metrology Institute (NMI) has developed a high precision profilometer traceable to the SI meter definition. The architecture of the machine contains a short and stable metrology frame dissociated from the supporting frame. It perfectly respects Abbe principle. The metrology loop incorporates three Renishaw laser interferometers and is equipped either with a chromatic confocal probe or a tactile probe to achieve measurements at the nanometric level of uncertainty. The machine allows the in situ calibration of the probes by means of a differential laser interferometer considered as a reference. In this paper, both the architecture and the operation of the LNE's high precision profilometer are detailed. A brief comparison of the behavior of the chromatic confocal and tactile probes is presented. Optical and tactile scans of an aspherical surface are performed and the large number of data are processed using the L BFGS (Limited memory Broyden Fletcher Goldfarb Shanno) algorithm. Fitting results are compared with respect to the evaluated residual errors which reflect the form defects of the surface.", "author_names": [ "E Nadim", "Nouira Hichem", "Anwer Nabil", "Damak Mohamed", "Gibaru Olivier" ], "corpus_id": 137558028, "doc_id": "137558028", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Comparison of tactile and chromatic confocal measurements of aspherical lenses for form metrology", "venue": "", "year": 2014 } ]

[ { "abstract": "The semiconductor manufacturing technologies have been evolving continuously since their invention. The semiconductor foundry industry, whose core business is contract semiconductor manufacturing service, is greatly influenced and shaped by the flow of these newly arriving technologies. This research applies the analytic hierarchy process (AHP) model to evaluate the strategic impact of new manufacturing technologies in the semiconductor foundry industry in Taiwan where the industry is in a global leadership position. The model incorporates the levels of overall competitive success, competitive goals, technology strategies, and emerging technologies. Relative impacts of elements in one level on its upper level are obtained by utilizing the inputs from experts of Taiwan semiconductor foundry industry. The results show the relative importance of competitive goals in the semiconductor foundry industry. Each competitive goal is aligned to the technology strategies as well as emerging technologies in the prioritized orders.", "author_names": [ "Jonathan C Ho" ], "corpus_id": 168506297, "doc_id": "168506297", "n_citations": 1, "n_key_citations": 0, "score": 2, "title": "Strategic Planning: Evaluation of Emerging Technologies in the Taiwan Semiconductor Foundry Industry", "venue": "", "year": 2016 }, { "abstract": "", "author_names": [ "Hemati Mohammad", "Samandizadeh Koroush" ], "corpus_id": 168090330, "doc_id": "168090330", "n_citations": 5, "n_key_citations": 0, "score": 1, "title": "STRATEGIC PLANNING EVALUATION IN MANUFACTURING COMPANIES THROUGH FUZZY ANALYTIC HIERARCHY PROCESS (FAHP)", "venue": "", "year": 2009 }, { "abstract": "Abstract The importance of strategic planning to small and mediumsized enterprises (SMEs) iswidely acknowledged by many practitioners and academiciansin SouthAfrica and the world over, yet there seems to be a paucity of research in thisfield. To address this dearth of published studies, the current study attempts to examine the influence of strategic planning aspects, namely employee participation, implementation incentives, and evaluation and control on business performance. The conceptualised modeland three hypotheses areempirically validated using a sample of 200 SMEs in Gauteng, South Africa. The findings indicate that strategic planning, in the form of employee participation, implementation incentives, and its evaluation and control, influences business performance in a significant way. In addition, managerial implications of the research findings and avenues for future research are provided.", "author_names": [ "Job Dubihlela", "Maxwell Sandada" ], "corpus_id": 55473192, "doc_id": "55473192", "n_citations": 22, "n_key_citations": 3, "score": 1, "title": "Impact of Strategic Planning on Small and Medium Sized Enterprises' (SMEs)Performance: The Role of Employee Participation, Implementation Incentives and Evaluation and Control", "venue": "", "year": 2014 }, { "abstract": "Technology developments are ushering in the introduction of smart manufacturing (SM) systems, unmanned production lines and sustainable production. SM will minimize human intervention and allow systems to control sites intelligently. To realize such an era, many global manufacturers are trying to develop different SM methods. The virtual factory is a digital manufacturing based SM system that predicts, solves (improves) and manages (controls) problems with overall production tasks by linking them to the actual sites, in a virtual environment. This paper proposes a strategic plan and a systematic design for the efficient implementation and application of the virtual factory to real manufacturing companies. In addition, an efficient and systematic means of introducing the virtual factory is presented via diagnosis, analysis and establishment of the strategy, implementation plan and system design case with an electronic parts manufacturing company.", "author_names": [ "Sangmin Choi", "Bo Hyun Kim", "Sang Do Noh" ], "corpus_id": 107244401, "doc_id": "107244401", "n_citations": 47, "n_key_citations": 3, "score": 1, "title": "A diagnosis and evaluation method for strategic planning and systematic design of a virtual factory in smart manufacturing systems", "venue": "", "year": 2015 }, { "abstract": "Aim Background: Strategic planning has been presented as an important management practice. However, evidence of its deployment in healthcare systems in low income and middle income countries (LMICs) is limited. This study investigated the strategic management process in Iranian hospitals. Methods: The present study was accomplished in 24 teaching hospitals in Tehran, Iran from September 2012 to March 2013. The data collection instrument was a questionnaire including 130 items. This questionnaire measured the situation of formulation, implementation, and evaluation of strategic plan as well as the requirements, facilitators, and its benefits in the studied hospitals. Results: All the investigated hospitals had a strategic plan. The obtained percentages for the items \"the rate of the compliance to requirements\" and \"the quantity of planning facilitators\" (68.75% attention to the stakeholder participation in the planning (55.74% attention to the planning components (62.22% the status of evaluating strategic plan (59.94% and the benefits of strategic planning for hospitals (65.15% were in the medium limit. However, the status of implementation of the strategic plan (53.71% was found to be weak. Significant statistical correlations were observed between the incentive for developing strategic plan and status of evaluating phase (P=0.04) and between status of implementation phase and having a documented strategic plan (P=0.03) Conclusion: According to the results, it seems that absence of appropriate internal incentive for formulating and implementing strategies led more hospitals to start formulation strategic planning in accordance with the legal requirements of Ministry of Health. Consequently, even though all the investigated hospital had the documented strategic plan, the plan has not been implemented efficiently and valid evaluation of results is yet to be achieved.", "author_names": [ "Jamil Sadeghifar", "Mehdi Jafari", "Shahram Tofighi", "Hamid Ravaghi", "Mohammadreza Maleki" ], "corpus_id": 17037445, "doc_id": "17037445", "n_citations": 16, "n_key_citations": 2, "score": 1, "title": "Strategic Planning, Implementation, and Evaluation Processes in Hospital Systems: A Survey From Iran", "venue": "Global journal of health science", "year": 2014 }, { "abstract": "", "author_names": [ "David R Arendale", "Hilda Barrow", "Kathy A Carpenter", "R Hodges", "Jane McGrath", "Pat Newell", "Janet Lynn Norton" ], "corpus_id": 168861436, "doc_id": "168861436", "n_citations": 1, "n_key_citations": 0, "score": 1, "title": "Strategic Planning Evaluation of Creating a New Professional Association.", "venue": "", "year": 2007 }, { "abstract": "These nine guides address fundamental components of planning and implementing a comprehensive underage drinking prevention program. The guides are designed to be brief, easy to read, and easy to use. Each guide contains a resource section to assist readers in obtaining additional and detailed information about the topics covered in that guide. The appendices include useful tools for each topic area that provide coalitions and organizations a jump start in their planning and implementation activities. Topics covered in the guides include: coalition building; needs assessment and strategic planning; evaluation; prevention and education; underage drinking enforcement; public policy advocacy; media relations; self sufficiency; and resources.", "author_names": [ "Pamela Beer", "Thomas L Leonard" ], "corpus_id": 152494826, "doc_id": "152494826", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "UNDERAGE DRINKING PREVENTION: COMMUNITY HOW TO GUIDE ON. COALITION BUILDING, NEEDS ASSESSMENT STRATEGIC PLANNING, EVALUATION, PREVENTION EDUCATION, ENFORCEMENT, PUBLIC POLICY, MEDIA RELATIONS, SELF SUFFICIENCY, AND RESOURCES", "venue": "", "year": 2001 }, { "abstract": "Abstract Decision making process in selecting the most suitable technological solutions for electricity power generation in terms of strategic planning comprises a rather complex procedure with several contradicting factors involved. In this context, development of an appropriate evaluation methodology that will provide decision makers with a useful tool is the aim of the specific study. To achieve this, the Delphi method is used in order to compare a number of alternative technologies with respect to several characteristics, e.g. cost, environmental impacts, social impacts and technological status. According to this method, a properly formed questionnaire is sent to a number of experts, currently related to the power generation sector. After the evaluation of results, weight factors are determined, so that the different technologies can be ranked according to both their scoring in each criterion category and their global scoring, independently of categories, on the basis of a multi criteria analysis. Emphasis is currently given on the electricity generation sector of Greece, with application of the developed methodology carried out for Crete, i.e. the biggest Greek island.", "author_names": [ "John K Kaldellis", "Alexandros Anestis", "Irene Koronaki" ], "corpus_id": 95124859, "doc_id": "95124859", "n_citations": 20, "n_key_citations": 1, "score": 0, "title": "Strategic planning in the electricity generation sector through the development of an integrated Delphi based multi criteria evaluation model", "venue": "", "year": 2013 }, { "abstract": "In response to market pressures, manufacturers have adopted different approaches to provide flexibility regarding several aspects. In this paper, we suggest a model for the evaluation of the flexibility of the manufacturing supply chain, based on graph theory techniques. This model defines maximum excess demand that may be met using flexibility. Recourse to flexibility enablers is determined based on cost minimisation. Such enablers are volume flexibility, mix flexibility and safety stocks. The proposed model is solved using a two step Mix Integer Linear Programme; the first step consists in defining maximum demand that may be met while the second step concerns minimising cost. The main benefit of our model is to deal with realistic problems in a rather short time. Therefore, it can be used in a wide 'what if' design process. It means evaluating various contemplated flexibility configurations in multiple demand scenarios in order to choose the best option. It can be also used during operational supply chain planning in order to face to an unbalanced situation. This paper ends with a numerical example illustrating our model's efficiency.", "author_names": [ "S Kemmoe", "Pierre-Alban Pernot", "Nikolay Tchernev" ], "corpus_id": 109289851, "doc_id": "109289851", "n_citations": 15, "n_key_citations": 1, "score": 1, "title": "Model for flexibility evaluation in manufacturing network strategic planning", "venue": "", "year": 2014 }, { "abstract": "Abstract Urban strategic planning and urban vulnerability assessment have increasingly become important issues in both policy agenda and academia. However, a comprehensive review of the advances made in urban vulnerability, emphasizing their shared aspects, has yet to be performed. The aiming of this paper is to addresses the latter by conducting an evaluation on assessment methods disclosed in this decade. Once their common evolutive pathway is traced, the review follows an analytical framework, based on the above, evaluating the research requirements from both a quantitative and qualitative point of view. Our findings indicate that the robustness, cognitive and participatory research lines are those in which most advancement has been made, while those of urban dynamics and multi scale progressed the least. Our analysis also demonstrates that methods integrating more lines of research, as well as the employment of comprehensive approaches, promotes advancing the developmental stage. We conclude that the focusing of research lines should be shifted, in order to bridge the qualitative gap identified without demanding an improbable, quantitative increase.", "author_names": [ "Jorge Salas", "Victor Yepes" ], "corpus_id": 159008246, "doc_id": "159008246", "n_citations": 25, "n_key_citations": 0, "score": 1, "title": "Urban vulnerability assessment: Advances from the strategic planning outlook", "venue": "", "year": 2018 } ]

[ { "abstract": "Solution processed electronic and optoelectronic devices offer low cost, large device area, physical flexibility and convenient materials integration compared to conventional epitaxially grown, lattice matched, crystalline semiconductor devices. Although the electronic or optoelectronic performance of these solution processed devices is typically inferior to that of those fabricated by conventional routes, this can be tolerated for some applications in view of the other benefits. Here we report the fabrication of solution processed infrared photodetectors that are superior in their normalized detectivity (D* the figure of merit for detector sensitivity) to the best epitaxially grown devices operating at room temperature. We produced the devices in a single solution processing step, overcoating a prefabricated planar electrode array with an unpatterned layer of PbS colloidal quantum dot nanocrystals. The devices showed large photoconductive gains with responsivities greater than 103 A W 1. The best devices exhibited a normalized detectivity D* of 1.8 x 1013 jones (1 jones 1 cm Hz1/2 W 1) at 1.3 um at room temperature: today's highest performance infrared photodetectors are photovoltaic devices made from epitaxially grown InGaAs that exhibit peak D* in the 1012 jones range at room temperature, whereas the previous record for D* from a photoconductive detector lies at 1011 jones. The tailored selection of absorption onset energy through the quantum size effect, combined with deliberate engineering of the sequence of nanoparticle fusing and surface trap functionalization, underlie the superior performance achieved in this readily fabricated family of devices.", "author_names": [ "Gerasimos Konstantatos", "I Howard", "Armin Fischer", "Sjoerd Hoogland", "Jason Paul Clifford", "Ethan J D Klem", "Larissa Levina", "Edward H Sargent" ], "corpus_id": 4430791, "doc_id": "4430791", "n_citations": 1369, "n_key_citations": 19, "score": 2, "title": "Ultrasensitive solution cast quantum dot photodetectors", "venue": "Nature", "year": 2006 }, { "abstract": "InGaAs based photodetectors have been generally used for detection in the short wave infrared (SWIR) region. However, the epitaxial process used to grow these materials is expensive; therefore, InGaAs based photodetectors are limited to space exploration and military applications. Many researchers have expended considerable efforts to address the problem of SWIR photodetector development using lead sulfide (PbS) quantum dots (QDs) Along with their cost efficient solution processability and flexible substrate compatibility, PbS QDs are highly interesting for the quantum size effect tunability of their bandgaps, spectral sensitivities, and wide absorption ranges. However, the performance of PbS QD based SWIR photodetectors is limited owing to inefficient carrier transfer and low photo and thermal stabilities. In this study, a simple method is proposed to overcome these problems by incorporating CdS in PbS QD shells to provide efficient carrier transfer and enhance the long term stability of SWIR photodetectors against oxidation. The SWIR photodetectors fabricated using thick shell PbS/CdS QDs exhibited a high on/off (light/dark) ratio of 11.25 and a high detectivity of 4.0 x 10 12 Jones, which represents a greater than 10 times improvement in these properties relative to those of PbS QDs. Moreover, the lifetimes of thick shell PbS/CdS QD based SWIR photodetectors were significantly improved owing to the self passivation of QD surfaces.", "author_names": [ "Jin-Beom Kwon", "Sae-Wan Kim", "Byoung-Ho Kang", "Se-Hyuk Yeom", "Wang-Hoon Lee", "Dae-Hyuk Kwon", "Jae-Sung Lee", "Shin-Won Kang" ], "corpus_id": 221136999, "doc_id": "221136999", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Air stable and ultrasensitive solution cast SWIR photodetectors utilizing modified core/shell colloidal quantum dots", "venue": "Nano Convergence", "year": 2020 }, { "abstract": "2D transition metal dichalcogenide (2D TMD) materials and their van der Waals heterostructures (vdWHs) have inspired worldwide efforts in the fields of electronics and optoelectronics. However, photodetectors based on 2D/2D vdWHs suffer from performance limitations due to the weak optical absorption of their atomically thin nature. In this work, taking advantage of an excellent light absorption coefficient, low temperature solution processability, and long charge carrier diffusion length, all inorganic halides perovskite CsPbI3 x Br x quantum dots are integrated with monolayer MoS2 for high performance and low cost photodetectors. A favorable energy band alignment facilitating interfacial photocarrier separation and efficient carrier injection into the MoS2 layer inside the 0D 2D mixed dimensional vdWHs are confirmed by a series of optical characterizations. Owing to the synergistic effect of the photogating mechanism and the modulation of Schottky barriers, the corresponding phototransistor exhibits a high photoresponsivity of 7.7 x 104 A W 1, a specific detectivity of 5.6 x 1011 Jones, and an external quantum efficiency exceeding 107% The demonstration of such 0D 2D mixed dimensional heterostructures proposed here would open up a wide realm of opportunities for designing low cost, flexible transparent, and high performance optoelectronics.", "author_names": [ "Hualin Wu", "Haonan Si", "Zihan Zhang", "Zhuo Kang", "Pingwei Wu", "Lixin Zhou", "Suicai Zhang", "Zheng Zhang", "Qingliang Liao", "Yue Zhang" ], "corpus_id": 56595185, "doc_id": "56595185", "n_citations": 77, "n_key_citations": 2, "score": 0, "title": "All Inorganic Perovskite Quantum Dot Monolayer MoS2 Mixed Dimensional van der Waals Heterostructure for Ultrasensitive Photodetector", "venue": "Advanced science", "year": 2018 }, { "abstract": "In article number 1801219, Zhuo Kang, Yue Zhang, and co workers fabricate an ultrasensitive photodetector based on an all inorganic perovskite quantum dot monolayer MoS2 mixed dimensional van der Waals heterostructure. Owing to the synergistic effect of photogating and Schottky barriers modulation, the corresponding phototransistor exhibits an ultrahigh photoresponsivity of 7.7 x 104 A W 1, a specific detectivity of 5.6 x 1011 Jones, and an external quantum efficiency exceeding 107%", "author_names": [ "Hualin Wu", "Haonan Si", "Zihan Zhang", "Zhuo Kang", "Pingwei Wu", "Lixin Zhou", "Suicai Zhang", "Zheng Zhang", "Qingliang Liao", "Yue Zhang" ], "corpus_id": 56595593, "doc_id": "56595593", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Optoelectronics: All Inorganic Perovskite Quantum Dot Monolayer MoS2 Mixed Dimensional van der Waals Heterostructure for Ultrasensitive Photodetector (Adv. Sci. 12/2018)", "venue": "Advanced Science", "year": 2018 }, { "abstract": "Recently, two dimensional (2D) materials, especially transition metal dichalcogenides (TMDCs) have attracted extensive interest owing to their potential applications in optoelectronics. Here, we demonstrate a hybrid 2D zero dimensional (0D) photodetector, which consists of a single layer or few layer molybdenum disulfide (MoS2) thin film and a thin layer of core/shell zinc cadmium selenide/zinc sulfide (ZnCdSe/ZnS) colloidal quantum dots (QDs) It is worth mentioning that the photoresponsivity of the hybrid 2D 0D photodetector is 3 orders of magnitude larger than the TMDC photodetector (from 10 to 104 A W 1) The detectivity of the hybrid structure detector is up to 1012 Jones, and the gain is up to 105. Due to an effective energy transfer from the photoexcited QD sensitizing layer to MoS2 films, light absorption is enhanced and more excitons are generated. Thus, this hybrid 2D 0D photodetector takes advantage of high charge mobility in the MoS2 layer and efficient photon absorption/exciton generation in the QDs, which suggests their promising applications in the development of TMDC based optoelectronic devices.", "author_names": [ "Shukui Zhang", "Xudong Wang", "Yan Chen", "Guangjian Wu", "Yicheng Tang", "Liqing Zhu", "Haoliang Wang", "Wei Jiang", "Liaoxin Sun", "Tie Lin", "Hong Shen", "Weida Hu", "Jun Ge", "Jianlu Wang", "Xiangjian Meng", "Jun-hao Chu" ], "corpus_id": 206496715, "doc_id": "206496715", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "Ultrasensitive Hybrid MoS2 ZnCdSe Quantum Dot Photodetectors with High Gain.", "venue": "ACS applied materials interfaces", "year": 2019 }, { "abstract": "PbS colloidal quantum dots (CQDs) passivated by thiocyanate anion (SCN are developed to combine with perovskite (CH3NH3PbI3) as building blocks for UV vis NIR broadband pho todetectors. Both high electrical conductivity and appropriate energy level alignment are obtained by the in situ ligand exchange with SCN The PbS SCN/CH3NH3PbI3 composite photodetectors are sensitive to a broad wavelength range covering the UV vis NIR region (365 1550 nm) possessing an excellent responsivity of 255 AW 1 at 365 nm and 1.58 AW 1 at 940 nm, remarkably high detectivity of 4.9x1013 Jones at 365 nm and 3.0x1011 Jones at 940 nm, and a fast response time 42 ms. Furthermore, a 10x10 photodetector array is fabricated and integrated, which constitutes a high performance broadband image sensor. Our approach paves a way for the development of highly sensitive broadband photodetectors/imagers that can be easily integrated.", "author_names": [ "Jing-Yue Zhang", "Jian-Long Xu", "Tong Chen", "Xu Gao", "Sui-Dong Wang" ], "corpus_id": 207904423, "doc_id": "207904423", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Toward Broadband Imaging: Surface Engineered PbS Quantum Dot/Perovskite Composite Integrated Ultrasensitive Photodetectors.", "venue": "ACS applied materials interfaces", "year": 2019 }, { "abstract": "", "author_names": [ "Jingzhou Li", "Changjiu Teng", "Bilu Liu", "Guichuan Xing", "Feiyu Kang" ], "corpus_id": 213052848, "doc_id": "213052848", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "Ultrasensitive Organic Modulated CsPbBr 3 Quantum Dot Photodetectors via Fast Interfacial Charge Transfer", "venue": "", "year": 2019 }, { "abstract": "We report that spin cast colloidal quantum dot devices depend sensitively on exquisite control over surface passivation. We use these findings to quadruple infrared phovotovoltaic efficiency and build the first megahertz frequency solution cast photodiode.", "author_names": [ "D Aaron R Barkhouse", "Jason Paul Clifford", "Andras G Pattantyus-Abraham", "Larissa Levina", "Edward H Sargent" ], "corpus_id": 138308675, "doc_id": "138308675", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Engineering Quantum Dot Surfaces in Solution Processed Optoelectronics: Chemical Optimization of Photodetector and Photovoltaic Device Performance", "venue": "", "year": 2009 }, { "abstract": "Broadband photodetectors have important applications in both scientific and industrial sectors. In this study, we report room temperature operated solution processed photodetectors by PbSe quantum dots (QDs) with spectral response from 350 to 2500 nm. In order to boost both external quantum efficiency (EQE) and projected detectivity D* the hole trap assisted photomultiplication effect through the EDT PbSe QD/TABI PbSe QD double thin layer thin film, where EDT PbSe QDs are 1,2 ethanedithiol (EDT) capped PbSe QDs and TABI PbSe QDs are tetrabutylammonium (TABI) capped PbSe QDs, is applied. To further enhance D* a thin layer of the conjugated polyelectrolyte, which offers significant hole injection resistance for suppressing dark current but enhancing photocurrent under illumination due to the photoinduced self doping process, is applied for reengineering the electron extraction layer in PbSe QD based photodetectors. As a result, at room temperature, PbSe QD based photodetectors exhibit over 450% EQE and over ~1012 Jones D* in the visible region and over 120% EQE and D* ~4 x 1011 Jones in the infrared region. These results demonstrate that our studies provide a simple approach to realize room temperature operated solution processed broadband photodetectors.", "author_names": [ "Tao Zhu", "Luyao Zheng", "Xiang Yao", "Lei Liu", "Fei Huang", "Yong Cao", "Xiong Gong" ], "corpus_id": 73430557, "doc_id": "73430557", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Ultrasensitive Solution Processed Broadband PbSe Photodetectors through Photomultiplication Effect.", "venue": "ACS applied materials interfaces", "year": 2019 }, { "abstract": "Sensing from ultraviolet visible to infrared is critical for both scientific and industrial applications. In this work, we demonstrate solution processed ultrasensitive broad band photodetectors (PDs) utilizing organolead halide perovskite materials (CH3NH3PbI3) and PbS quantum dots (QDs) as light harvesters. Through passivating the structural defects on the surface of PbS QDs with diminutive molecular scaled CH3NH3PbI3, both trap states in the bandgap of PbS QDs for charge carrier recombination and the leakage currents occurring at the defect sites are significantly reduced. In addition, CH3NH3PbI3 itself is an excellent light harvester in photovoltaics, which contributes a great photoresponse in the ultraviolet visible region. Consequently, operated at room temperature, the resultant PDs show a spectral response from 375 nm to 1100 nm, with high responsivities over 300 mA W( 1) and 130 mA W( 1) high detectivities exceeding 10(13) Jones (1 Jones 1 cm Hz(1/2) W( 1) and 5 x 10(12) Jones in the visible and near infrared regions, respectively. These device performance parameters are comparable to those from pristine inorganic counterparts. Thus, our results offer a facile and promising route for advancing the performance of broad band PDs.", "author_names": [ "Chang Liu", "Kai Wang", "Pengcheng Du", "Enmin Wang", "Xiong Gong", "Alan J Heeger" ], "corpus_id": 205980770, "doc_id": "205980770", "n_citations": 73, "n_key_citations": 1, "score": 0, "title": "Ultrasensitive solution processed broad band photodetectors using CH3NH3PbI3 perovskite hybrids and PbS quantum dots as light harvesters.", "venue": "Nanoscale", "year": 2015 } ]

[ { "abstract": "Photoplethysmography (PPG) is a simple and low cost optical technique that can be used to detect blood volume changes in the microvascular bed of tissue. It is often used non invasively to make measurements at the skin surface. The PPG waveform comprises a pulsatile 'AC' physiological waveform attributed to cardiac synchronous changes in the blood volume with each heart beat, and is superimposed on a slowly varying 'DC' baseline with various lower frequency components attributed to respiration, sympathetic nervous system activity and thermoregulation. Although the origins of the components of the PPG signal are not fully understood, it is generally accepted that they can provide valuable information about the cardiovascular system. There has been a resurgence of interest in the technique in recent years, driven by the demand for low cost, simple and portable technology for the primary care and community based clinical settings, the wide availability of low cost and small semiconductor components, and the advancement of computer based pulse wave analysis techniques. The PPG technology has been used in a wide range of commercially available medical devices for measuring oxygen saturation, blood pressure and cardiac output, assessing autonomic function and also detecting peripheral vascular disease. The introductory sections of the topical review describe the basic principle of operation and interaction of light with tissue, early and recent history of PPG, instrumentation, measurement protocol, and pulse wave analysis. The review then focuses on the applications of PPG in clinical physiological measurements, including clinical physiological monitoring, vascular assessment and autonomic function.", "author_names": [ "John Allen" ], "corpus_id": 11450080, "doc_id": "11450080", "n_citations": 1658, "n_key_citations": 77, "score": 1, "title": "Photoplethysmography and its application in clinical physiological measurement.", "venue": "Physiological measurement", "year": 2007 }, { "abstract": "The photoplethysmograph has been used for over 50 years but there are still misconceptions in how and what is the information obtained. A photoplethysmograph signal from any site on the skin can be separated into an oscillating (a.c. and a steady state (d.c. component, their amplitudes dependent upon the structure and flow in the vascular bed. Many simple applications are available: pulse counters, using the a.c. component, skin colour and haemoglobin saturation meters, using the d.c. component. The d.c. component of the photoplethysmograph signal is a function of the blood flux beneath the device. A good emitter for use in a photoplethysmograph of skin blood flow is one in the frequency range 600 700 nm and the best signal for a.c. analysis is obtained from the finger pulp. The frequency range of the electronic circuitry should be from 0.01 to 15 Hz, then all the information in the signal can be extracted about the autonomic nervous system control of the cardiovascular system, particularly between 0.01 and 2 Hz. Comparative studies may be drawn between similar skin sites on a subject or between subjects if the afferent inputs to the brain stem are controlled or driven at a known frequency. These afferents, inputs, will modulate the efferents, outputs, which generate variations in the a.c. component of the detected photoplethysmograph signal.", "author_names": [ "Ahmad A Kamal", "J B Harness", "Glenn Irving", "Alan J Mearns" ], "corpus_id": 4534758, "doc_id": "4534758", "n_citations": 252, "n_key_citations": 11, "score": 0, "title": "Skin photoplethysmography a review.", "venue": "Computer methods and programs in biomedicine", "year": 1989 }, { "abstract": "Motion artifact reduction in photoplethysmography, and therefore by implication in pulse oximetry, is achieved with a novel nonlinear methodology. The physical origins of the photoplethysmographic signals are explored in relation to a nonlinear measure of the observed intensity fluctuations. It is demonstrated that the nonlinearity renormalizes the received pulsations with optical information in a manner that aids physical interpretation. A heuristic physical model for the motion artifact is introduced and experimentally justified, with an inversion for artifact reduction being simplified by the nonlinearity. A practical implementation technique is discussed with emphasis placed on the resultant rescaling of the static and the dynamic portions of the signals. It is noted that this implementation also has the desirable effect of reducing any residual ambient artifact. The scope and power of this methodology is investigated with the presentation of results from a practical electronic system.", "author_names": [ "Matthew James Hayes", "P R Smith" ], "corpus_id": 43496499, "doc_id": "43496499", "n_citations": 69, "n_key_citations": 4, "score": 0, "title": "Artifact reduction in photoplethysmography.", "venue": "Applied optics", "year": 1998 }, { "abstract": "This report evaluates the efficacy of reflected type green light photoplethysmography (green light PPG) Transmitted infrared light was used for PPG and the arterial pulse was monitored transcutaneously. The reflected PPG signal contains AC components based on the heartbeat related signal from the arterial blood flow and DC components, which include reflectance and scattering from tissue. Generally, changes in AC components are monitored, but the DC components play an important role during heat stress. In this study, we compared the signal of green light PPG to infrared PPG and ECG during heat stress. The wavelengths of the green and infrared light were 525 nm and 880 nm, respectively. Experiments were performed on young healthy subjects in cold (10degC) hot (45degC) and normal environments. The pulse rates were compared among three measurement devices and the AC and DC components of the PPG signal were evaluated during heat stress. The pulse rates obtained from green light PPG were strongly correlated with the R R interval of an electrocardiogram in all environments, but those obtained from infrared light PPG displayed a weaker correlation with cold exposure. The AC components were of similar signal output for both wavelengths during heat stress. Also, the DC components for green light PPG were similar during heat stress, but showed less signal output for infrared light PPG during hot exposure. The main reason for the reduced DC components was speculated to be the increased blood flow at the vascular bed. Therefore, reflected green light PPG can be useful for pulse rate monitoring because it is less influenced by the tissue and vein region.", "author_names": [ "Yuka Maeda", "Masaki Sekine", "Toshiyo Tamura" ], "corpus_id": 22151842, "doc_id": "22151842", "n_citations": 116, "n_key_citations": 2, "score": 2, "title": "The Advantages of Wearable Green Reflected Photoplethysmography", "venue": "Journal of Medical Systems", "year": 2010 }, { "abstract": "Removing the motion artifacts from measured photoplethysmography (PPG) signals is one of the important issues to be tackled for the accurate measurement of arterial oxygen saturation during movement. In this paper, the motion artifacts were reduced by exploiting the quasi periodicity of the PPG signal and the independence between the PPG and the motion artifact signals. The combination of independent component analysis and block interleaving with low pass filtering can reduce the motion artifacts under the condition of general dual wavelength measurement. Experiments with synthetic and real data were performed to demonstrate the efficacy of the proposed algorithm.", "author_names": [ "Byung S Kim", "Sun Kook Yoo" ], "corpus_id": 9629645, "doc_id": "9629645", "n_citations": 333, "n_key_citations": 17, "score": 0, "title": "Motion artifact reduction in photoplethysmography using independent component analysis", "venue": "IEEE Transactions on Biomedical Engineering", "year": 2006 }, { "abstract": "In this paper we assessed the possibility of using the pulse rate variability (PRV) extracted from the photoplethysmography signal as an alternative measurement of the HRV signal in non stationary conditions. The study is based on analysis of the changes observed during a tilt table test in the heart rate modulation of 17 young subjects. First, the classical indices of HRV analysis were compared to the indices from PRV in intervals where stationarity was assumed. Second, the time varying spectral properties of both signals were compared by time frequency (TF) and TF coherence analysis. Third, the effect of replacing PRV with HRV in the assessment of the changes of the autonomic modulation of the heart rate was considered. Time invariant HRV and PRV indices showed no statistically significant differences (p 0.05) and high correlation >0.97) Time frequency analysis revealed that the TF spectra of both signals were highly correlated (0.99 0.01) the difference between the instantaneous power, in the LF and HF bands, obtained from HRV and PRV was small <10( 3) s( 2) and their temporal patterns were highly correlated (0.98 0.04 and 0.95 0.06 in the LF and HF bands, respectively) and TF coherence in the LF and HF bands was high (0.97 0.04 and 0.89 0.08, respectively) Finally, the instantaneous power in the LF band was observed to significantly increase during head up tilt by both HRV and PRV analysis. These results suggest that although some differences in the time varying spectral indices extracted from HRV and PRV exist, mainly in the HF band associated with respiration, PRV could be used as a surrogate of HRV during non stationary conditions, at least during the tilt table test.", "author_names": [ "Eduardo Gil", "Michele Orini", "Raquel Bailon", "Jose Maria Vergara", "Luca T Mainardi", "Pablo Laguna" ], "corpus_id": 31430958, "doc_id": "31430958", "n_citations": 333, "n_key_citations": 22, "score": 0, "title": "Photoplethysmography pulse rate variability as a surrogate measurement of heart rate variability during non stationary conditions.", "venue": "Physiological measurement", "year": 2010 }, { "abstract": "Heart rate variability (HRV) is traditionally derived from RR interval time series of electrocardiography (ECG) Photoplethysmography (PPG) also reflects the cardiac rhythm since the mechanical activity of the heart is coupled to its electrical activity. Thus, theoretically, PPG can be used for determining the interval between successive heartbeats and heart rate variability. However, the PPG wave lags behind the ECG signal by the time required for transmission of pulse wave. In this study, finger tip PPG and standard lead II ECG were recorded for five minutes from 10 healthy subjects at rest. The results showed a high correlation (median 0.97) between the ECG derived RR intervals and PPG derived peak to peak (PP) intervals. PP variability was accurate (0.1 ms) as compared to RR variability. The time domain, frequency domain and Poincare plot HRV parameters computed using RR interval method and PP interval method showed no significant differences (p 0.05) The error analysis also showed insignificant differences between the HRV indices obtained by the two methods. Bland Altman analysis showed high degree of agreement between the two methods for all the parameters of HRV. Thus, HRV can also be reliably estimated from the PPG based PP interval method.", "author_names": [ "Nandakumar Selvaraj", "A K Jaryal", "J Santhosh", "Kishore Kumar Deepak", "Sneh Anand" ], "corpus_id": 10165596, "doc_id": "10165596", "n_citations": 266, "n_key_citations": 22, "score": 0, "title": "Assessment of heart rate variability derived from finger tip photoplethysmography as compared to electrocardiography", "venue": "Journal of medical engineering technology", "year": 2008 }, { "abstract": "Heart rate variability (HRV) extracted from an electrocardiogram, is known to be a noninvasive indicator reflecting the dynamic interplay between perturbations to cardiovascular function and the dynamic response of the cardiovascular regulatory system. Photoplethysmography (PPG) is a noninvasive method to monitor arterial oxygen saturation on a continuous basis. Given the rich cardiovascular information in the PPG signal, and the ubiquity and simplicity of pulse oximetry, we are investigating the feasibility of acquiring dynamics pertaining to the autonomic nervous system from PPG waveforms. To do this, we are quantifying PPG variability (PPGV) Detailed algorithmic approaches for extracting accurate PPGV signals are presented. We compare PPGV to HRV by computing time and frequency domain parameters often associated with HRV measurements, as well as approximate entropy calculations. Our results demonstrate that the parameters of PPGV are highly correlated with the parameters of HRV. Thus, our results indicate that PPGV could be used as an alternative measurement of HRV.", "author_names": [ "Sheng Lu", "He Zhao", "Kihwan Ju", "Kun-Su Shin", "Myoungho Lee", "Kirk H Shelley", "Ki H Chon" ], "corpus_id": 33695409, "doc_id": "33695409", "n_citations": 238, "n_key_citations": 12, "score": 0, "title": "Can Photoplethysmography Variability Serve as an Alternative Approach to Obtain Heart Rate Variability Information?", "venue": "Journal of Clinical Monitoring and Computing", "year": 2007 }, { "abstract": "An apparatus for simultaneously monitoring heart and respiratory rates was developed using photoplethysmography (PPG) and digital filters, and compared with conventional methods. The PPG signal, which includes both heart and respiratory components, was measured at the earlobe with an original transmission mode photoplethysmographic device. A digital filtering technique was used to distinguish heart and respiratory signals from the PPG signal. The cut off frequency of the respiratory signal filter was selected automatically depending on the heart rate. Using digital filtering techniques, heart and respiratory signals were separated at rest and during exercise. The digital signal processor was employed to realize an adaptive and real time filtering. The heart rate was calculated by the zero crossing method and the respiratory rate from the peak interval of the filtered signal. To evaluate the newly developed monitor, an ECG for heart rate and a transthoracic impedance plethysmogram for respiratory rate were monitored simultaneously. To obtain higher heart and respiratory rates, exercise was performed on an electrical bicycle ergometer. Heart and respiratory rates calculated by the new method compare to those obtained from ECG and the transthoracic impedance plethysmogram. The maximum error of heart and respiratory rates was 10 beats/min and 7 breaths/min, respectively.", "author_names": [ "Kazuki Nakajima", "Toshiyo Tamura", "Hidetoshi Miike" ], "corpus_id": 43417761, "doc_id": "43417761", "n_citations": 226, "n_key_citations": 7, "score": 0, "title": "Monitoring of heart and respiratory rates by photoplethysmography using a digital filtering technique.", "venue": "Medical engineering physics", "year": 1996 }, { "abstract": "This paper addresses the design considerations and critical evaluation of a novel embodiment for wearable photoplethysmography (PPG) comprising a magnetic earring sensor and wireless earpiece. The miniaturized sensor can be worn comfortably on the earlobe and contains an embedded accelerometer to provide motion reference for adaptive noise cancellation. The compact wireless earpiece provides analog signal conditioning and acts as a data forwarding device via a radio frequency transceiver. Using Bland Altman and correlation analysis, we evaluated the performance of the proposed system against an FDA approved ECG measurement device during daily activities. The mean standard deviation (SD) of the differences between heart rate measurements from the proposed device and ECG (expressed as percentage of the average between the two techniques) along with the 95% limits of agreement (LOA 1.96 SD) was 0.62% 4.51% (LOA 8.23% and 9.46% 0.49% 8.65% 17.39% and 16.42% and 0.32% 10.63% 21.15% and 20.52% during standing, walking, and running, respectively. Linear regression indicated a high correlation between the two measurements across the three evaluated conditions (r 0.97, 0.82, and 0.76, respectively with p 0.001) The new earring PPG system provides a platform for comfortable, robust, unobtrusive, and discreet monitoring of cardiovascular function.", "author_names": [ "Ming-Zher Poh", "Nicholas C Swenson", "Rosalind W Picard" ], "corpus_id": 5107322, "doc_id": "5107322", "n_citations": 157, "n_key_citations": 4, "score": 0, "title": "Motion tolerant magnetic earring sensor and wireless earpiece for wearable photoplethysmography", "venue": "IEEE Transactions on Information Technology in Biomedicine", "year": 2010 } ]

[ { "abstract": "Using a fiber optic temperature sensing system based on the cross correlation of picosecond optical pulses from a gain switched semiconductor laser, the thermal time constants of several types of optical fiber in water were measured.", "author_names": [ "Kazunari Tokunaga", "Yoshitaka Naito", "Tetsuya Matsuyama" ], "corpus_id": 225398820, "doc_id": "225398820", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Measurement of thermal time constant of optical fiber using linear cross correlation of optical pulses", "venue": "2020 Conference on Lasers and Electro Optics Pacific Rim (CLEO PR)", "year": 2020 }, { "abstract": "Coherent optical frequency comb based on single section semiconductor quantum dots mode locked laser (QD MLL) is a promising device, which is able to provide a large number of equally spaced spectral lines simultaneously. We discuss the measurements and the spectral properties of QD MLL, including relative intensity noise, phase noise of each individual spectral line, as well as differential phase noise between spectral lines. More specifically, we report the frequency dependent nature of QD MLL phase noises, and its impact in the performance of coherent communication systems.", "author_names": [ "Rongqing Hui", "Mustafa Al-Qadi", "M O'sullivan", "Chongjin Xie" ], "corpus_id": 221912374, "doc_id": "221912374", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Spectral Properties of Quantum Dots Mode Locked Diode Lasers and the Impact in Fiber Optic Systems", "venue": "2020 22nd International Conference on Transparent Optical Networks (ICTON)", "year": 2020 }, { "abstract": "Surface trapped electromagnetic waves can be localized at a boundary between a semiconductor distributed Bragg reflector (DBR) and the air. These waves enable a novel class of both in plane emitting and vertically emitting optical devices including edge emitting lasers, disk microlasers, near field fiber coupled lasers as well as vertical cavity surface emitting lasers (VCSELs) In oxide confined VCSEL structures the surface trapped mode can be used for engineering of coupled modes in the oxidized periphery region outside the aperture having a large overlap integral with the VCSEL modes inside the aperture region. Depending on the thickness of the distributed Bragg reflector layers, the thickness of the oxide layers and of the design of the top VCSEL cap layers, the interaction of these non orthogonal optical modes can result in the lateral leakage of the VCSEL emission into the oxidized periphery. High order transverse VCSEL aperture modes having a higher intensity at the aperture boundary can have preference for such leakage. Mapping of the VCSEL wafers in areas with the variable aperture diameters $D(\\sim 3\\ \\mu \\mathrm{m} \\text{to} \\sim 5\\ \\mu \\mathrm{m} shows non monotonous behavior of side mode suppression ratio (SMRS) between the fundamental and the excited mode versus $D$ oscillating in the range from 7 dB to ~30 dB with three clearly revealed maxima in the SMSR at particular aperture diameters. VCSELs manufactured show 40 Gb/s data transmission over 1.4 km OM5 multimode fiber without pre emphasis or equalization.", "author_names": [ "Nikolay N Ledentsov", "Vitaly A Shchukin", "Vladimir Kalosha", "Lukasz Chorchos", "Oleg Makarov" ], "corpus_id": 221915263, "doc_id": "221915263", "n_citations": 1, "n_key_citations": 0, "score": 1, "title": "Edge and Surface Emitting Lasers Applying TM Mode Confined at the Distributed Bragg Reflector Air Interface", "venue": "2020 22nd International Conference on Transparent Optical Networks (ICTON)", "year": 2020 }, { "abstract": "This paper introduces an integrated fiber physical unclonable function (PUF) verification system based on a semiconductor laser source at substantially lower complexity and cost than existing alternatives. A source sub section consisting of a linear frequency swept semiconductor laser is used in combination with an optical frequency domain reflectometry (OFDR)/LiDAR based measurement sub section in order to conduct fiber identification via measurement of the unique Rayleigh reflection pattern of a section of optical fiber. When using these Rayleigh reflection patterns as PUFs, this technique results in a maximum equal error rate (EER) of 0.15% for a 5 cm section of optical fiber and an EER of less than 1% for a 4 cm section. These results demonstrate that the system can serve as a robust method fiber identification for device and communication verification applications.", "author_names": [ "Zheyi Yao", "Thomas Mauldin", "Gerald Hefferman", "Zheyu Xu", "Ming Liu", "Tao Wei" ], "corpus_id": 201258594, "doc_id": "201258594", "n_citations": 7, "n_key_citations": 1, "score": 1, "title": "Low cost optical fiber physical unclonable function reader based on a digitally integrated semiconductor LiDAR.", "venue": "Applied optics", "year": 2019 }, { "abstract": "A novel scheme for all optical generate ultra wideband (UWB) pulse shape modulation (PSM) signals based on semiconductor fiber ring laser (SFRL) is proposed, in which three UWB PSM signals can be generated simultaneously. A comprehensive broad band dynamic model of this kind of all optical UWB PSM signals is presented and simulated. The numerical simulation results show that the central frequency (CF) of PSM signals, the 10dB bandwidth of PSM signals and the fractional bandwidth of PSM signals are 5GHz, 7GHz and 140% respectively, which satisfy the definition of the UWB.", "author_names": [ "Zan-shan Zhao" ], "corpus_id": 209457906, "doc_id": "209457906", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Research of all optical broadcast UWB pulse shape modulation signals based on semiconductor fiber ring laser", "venue": "2019 18th International Conference on Optical Communications and Networks (ICOCN)", "year": 2019 }, { "abstract": "Monolithic passively mode locked (PML) semiconductor lasers are attractive high speed photonic emitters potentially enabling novel future secure communication schemes [1] In this contribution, mutual all optical injection of two PML InAs/InGaAs quantum dot (QD) lasers emitting at 1250 nm with equal active region and waveguide geometry is studied experimentally for the first time and explained theoretically. The active regions of both two section lasers consist of 5 layers of InAs/InGaAs QDs, and the emission wavelengths are at around 1255 nm. Both cavity lengths amount to 2 mm with a 0.25 mm long absorber section at the back facet that is reverse biased at 4 V. The facets are anti reflective (front facet) and high reflective (back facet) coated. The lasers are stabilized at different heat sink temperatures (Laser 1: 15 degC, Laser 2: 24 degC) to ensure optimum wavelength overlap. Both lasers are mutually coupled by a setup, depicted schematically in Fig. 1a) Emission beams of both lasers are individually collimated and overlapped across a distance of approximately 1.65 m. Optical fine delay is implemented by a retro reflector mounted on a linear translation stage. Using a 50/50 beam splitter and incorporating two optical isolators >60 dB isolation) light from both directions can be fiber coupled and by an optical spectrum analyzer and a fast photo diode in combination with an electrical spectrum analyzer, spectral and radio frequency (RF) analysis can be performed. Both lasers are biased at 200 mA and the free running repetition rate (RR) amounts to 20.074 GHz for Laser 1 and 20.087 GHz for Laser 2. We translate the single path fine delay across 66 ps in steps of 1.47 ps and record both lasers repetition rates RR for the mutually injection scheme. Obtained results are depicted in Fig. 1b) as a function of the added time delay. We find that both RRs follow a saw tooth shaped dependence with plateaus which is attributed to the strong external optical self feedback stemming from the facets of the opposite laser [1] Furthermore, the well overlapping RRs of both lasers in Fig. 1b) indicate mutual injection locking, as analyzed in [2] In a second step, both lasers RRs are analyzed in dependence on the gain section biasing of Laser 1 of 100 mA to 250 mA in steps of 5 mA. Fig. 1c) displays the recorded RRs under mutual injection with Laser 2 biased at 200 mA. Additionally, we measure both RRs with the opposite laser unbiased in order to identify the influence of the OFB without the presence of the mutual injection signals (black and green curve in Fig 1c)", "author_names": [ "Christoph Weber", "Dominik Auth", "Iraklis Hercules Simos", "Christos Simos", "Stefan Breuer" ], "corpus_id": 204816619, "doc_id": "204816619", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Repetition Rate Locking of Mutually Injected Monolithic Passively Mode Locked Semiconductor Quantum Dot Lasers", "venue": "2019 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)", "year": 2019 }, { "abstract": "Self mode locked (SML) quantum dash (QDh) lasers emitting at around 1550 nm are compact broadband optical frequency comb (OFC) sources for multi wavelength communication applications [1,2] Optical self feedback (OFB) by auxiliary cavities with lengths in the meter range is a well established method for a precise and dynamical mode spacing control of passively mode locked (PML) semiconductor lasers. Recent works focused on identifying maximum tuning ranges of quantum well PML lasers and suggested that external OFB length, interaction width of fed back pulse with the pulse inside the laser cavity and the OFB strength appear predominant [3] In this contribution, we experimentally investigate and explain by modeling the dependence of mode spacing of OFB of SML QDh lasers subject to different cavity lengths on the external optical delay. Here, we study the impact of different OFB strengths and external OFB cavity lengths onto the mode spacing of QDh SML lasers. The three lasers investigated are 1 mm and 2 mm long, corresponding to a mode spacing of 40 GHz and 20 GHz, base on 6 and 9 layers of InAs/InGaAsP Qdhs [1,4] and exhibit as cleaved facets. In the developed experimental set up, sketched in Fig. 1a) the laser light is coupled into a lensed single mode fiber and a part of the light is directed to the hybrid fiber based and free space OFB cavity.", "author_names": [ "Patrick Fiala", "Dominik Auth", "Christoph Weber", "Quentin Gaimard", "Abderrahim Ramdane", "Stefan Breuer" ], "corpus_id": 204815750, "doc_id": "204815750", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Self Injected Optical Frequency Comb Quantum Dash Lasers", "venue": "2019 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)", "year": 2019 }, { "abstract": "Dual mode microcavity semiconductor lasers are investigated for potential applications in photonic microwave and optical frequency comb (OFC) generation. By regulating whispering gallery modes (WGMs) in square microcavities, dual mode lasing is achieved with frequency intervals ranging from tens to hundreds of gigahertz. In the square microcavities, the fundamental and first order transverse WGMs have spatially separated field distributions, which allow stable dual transverse mode lasing with mode intervals inversely proportional to the cavity areas. Dual transverse mode square microcavity lasers are experimentally demonstrated with frequency intervals ranging from ~35 to ~150 GHz. Photonic microwaves and OFCs are successfully generated based on the dual mode square microcavity lasers. To enhance the transverse mode intervals, circular side square microcavity lasers with a square hole in the center are proposed and demonstrated, and dual transverse mode lasing with a frequency interval up to ~0.56 THz is obtained. Furthermore, a square Fabry Perot coupled cavity microlaser is demonstrated to increase the output power and introduce an additional degree for manipulating the lasing modes. Dual mode lasing is realized with a frequency interval of ~0.5 THz, a single mode optical fiber coupled power of ~3 mW, and a wavelength tuning range of ~10 nm.", "author_names": [ "Hai-Zhong Weng", "Yuede Yang", "Ji-Liang Wu", "You-Zeng Hao", "Ming-Ying Tang", "Jin-Long Xiao", "Yongzhen Huang" ], "corpus_id": 181649788, "doc_id": "181649788", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Dual Mode Microcavity Semiconductor Lasers", "venue": "IEEE Journal of Selected Topics in Quantum Electronics", "year": 2019 }, { "abstract": "Optical chaos communication has advantages of high speed and long transmission distance. Unfortunately, the key space of the traditional transceiver, i.e. semiconductor laser with mirror feedback, is limited due to the time delay signature. In this paper, we propose and numerically demonstrate a key space enhancement by using semiconductor laser with optical feedback from a chirped fiber Bragg grating (FBG) The chirped FBG feedback can make feedback delay a key parameter by eliminating the time delay signature. Moreover, the grating dispersion and center frequency can also be used as new keys. As a result, the dimension of key space is increased. By taking a bidirectional communication scheme as an example, numerical results show that the key space is raised by 244 times as against mirror feedback with a data rate of 2.5 Gb/s and a coupling strength of 0.447. As the coupling strength decreases, the key space increases due to the fact that chaos synchronization becomes more sensitive to parameter mismatch.", "author_names": [ "Da Wang", "Louis S Wang", "Y Y Guo", "Yu Cheng Wang", "A B Wang" ], "corpus_id": 73418966, "doc_id": "73418966", "n_citations": 20, "n_key_citations": 1, "score": 0, "title": "Key space enhancement of optical chaos secure communication: chirped FBG feedback semiconductor laser.", "venue": "Optics express", "year": 2019 }, { "abstract": "Extended cavity semiconductor lasers with high spectral purity and wide spectral coverage are important for a large range of applications including fiber optic communications [1] optical sensing [2] or applications in space, for instance in atomic clocks [3] Monolithic diode lasers for such tasks, e.g. distributed feedback (DFB) lasers and distributed Bragg reflector (DBR) lasers, approach their limits since they typically show either a small tuning range [4] or considerable spectral linewidths at the MHz level [5] These limitations can be largely removed in hybrid lasers, where the gain from a semiconductor optical amplifier chip is receiving spectrally filtered feedback from a second chip fabricated from dielectric material. The dielectric chip carries an integrated optical waveguide circuit with which highly selective filtering and a long photon lifetime can be realized beyond what is typically possible in semiconductor platforms.", "author_names": [ "Y Fan", "Jesse Mak", "Albert van Rees", "Edwin Jan Klein", "K -J Bolter" ], "corpus_id": 53614736, "doc_id": "53614736", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Extended Cavity Single Frequency Semiconductor Lasers using Ring Filters in Low Loss SiN Technology", "venue": "2018 IEEE International Semiconductor Laser Conference (ISLC)", "year": 2018 } ]

[ { "abstract": "418 MRS BULLETIN VOLUME 30 JUNE 2005 Organic Photodiodes Deposited on Newspaper Organic semiconductors have received significant interest recently and are under serious consideration for use in flexible electronics on a wide variety of substrates. In particular, organic photodiodes have seen rapid improvements in properties and performance. In a recent study, B. Lamprecht and co workers at Gunther Leising's Institute of Nanostructured Material and Photonics in Weiz, Austria, a division of Joanneum Research, have demonstrated the fabrication and characterization of organic photodiodes deposited on ordinary newspaper sheets. They reported their results in the April issue of Physica Status Solidi A (p. R50; DOI: 10.1002/pssa.200510010) The paper samples, taken from the German newspaper Die Zeit, were mounted on glass substrates during the fabrication process. The newspaper substrates were coated with a parylene C barrier layer (5 10 mm thick) which is an effective chemical and moisture barrier. Since the newspaper surface is rough, and the parylene coating does not provide a smoothing effect, an ORMOCER coating, which is a new class of silicate based inorganic organic hybrid polymer materials, was applied. The ORMOCER coating, ~100 mm thick, provided surface planarization and was inert to subsequent depositions of metal and organic layers. The rms surface roughness at this point was less than 3 nm. The organic charge generating layers were then deposited, sandwiched between a 55 nm thick gold bottom electrode and a 25 nm thick semitransparent silver top electrode. The fabricated organic photodiode, similar to the well understood Tang type pn heterojunction device, consisted of a p type conducting copper phthalocyanine (CuPc) and an n type perylene tetracarboxylic bisbenzimidazole. The organic and metal layers were deposited using room temperature, high vacuum sublimation. The fabricated devices were removed from the glass substrates prior to characterization. The current voltage characteristics of the devices were measured in the dark and under illumination using a halogen lamp, with white light passing through the semitransparent Ag electrode. In the dark, the devices showed a well pronounced rectification ratio of about 104 at 1 V. On illumination, the devices yielded a photocurrent exceeding the dark current by about six orders of magnitude when operated near a zero bias condition. No hysteresis effect was observed. The photodiodes yielded very good diode behavior. Also, in order to determine the spectral response of the device, measurements of spectrally resolved external quantum efficiency were carried out using a tungsten halogen lamp and a monochromator. The devices yielded a spectral response covering the complete ultraviolet and visible light range. The researchers said that although newspaper was used as an example, from a wider perspective, this study demonstrated that organic photodiode devices may likely be fabricated on almost any user defined substrate. GOPAL RAO", "author_names": [ "Amanda L Giermann" ], "corpus_id": 137799034, "doc_id": "137799034", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Al Based Tunnel Junctions Form Solid State Refrigerator Suitable for Sub Kelvin Applications", "venue": "", "year": 2005 }, { "abstract": "With the advent of SCUBA, the reef fish fauna has been substantially studied around the world, but the great majority of in situ studies have focused exclusively on a limited portion of this fauna, to depths of 30 m. The present study represents the first SCUBAbased survey of the deep reef fishes off the Brazilian coast between 35 and 70 m. A species list was compiled based on visual observations, collections, video recording, and fishes obtained from commercial fishing boats. A total of 158 fish species belonging to 49 families was recorded. Thirty two species were formally recorded for the first time from the study area, four of which [Apogon robbyi Gilbert, 1997; Coryphopterus eidolon Bohlke Robins, 1960; Psilotris batrachodes Bohlke, 1963; and Xanthichthys ringens (Linnaeus, 1758) represent new records for the western South Atlantic. Fifty seven species had their depth range extended to depths 40 m. The most species rich families were Carangidae (14 species) Gobiidae (12) Lutjanidae (11) Labridae (11) Serranidae (10) Haemulidae (8) and Scaridae (7) The presence of several species previously considered to have disjunct, or anti equatorial distribution, indicates that the deep reefs may function as a faunal corridor between habitats in southeastern Brazil and the Caribbean. With the advent of SCUBA, the coral reef ichthyofauna has been substantially studied around the world (see review by Sale, 1991) Even though ichthyologists have taken advantage of SCUBA technology for exploring and collecting specimens from coral reef habitats, the great majority of in situ studies have dealt exclusively with a limited portion of the reef fish fauna, to depths of 30 m (Thresher and Colin, 1986; Itzikowitz et al. 1991; Pyle, 2000) Direct observations of deep reef fishes using conventional SCUBA are sparse (e.g. Lukens, 1981; Rocha et al. 1998) and limited both by the working depth (down to about 60 m) and the restricted bottom time (because of the limited quantities of breathing gas carried and decompression problems) (Pyle, 1996a, 1998, 2000) The difficulties of working with direct observations on deep reefs have been overcome, in part, through the use of small research submersibles (e.g. Colin, 1974, 1976; Colin et al. 1986; Thresher and Colin, 1986; Pearcy et al. 1989; Itzikowitz et al. 1991; Stein et al. 1992) However, submersibles are extremely expensive to construct and operate, and require extensive logistical support. Moreover, submersibles cannot effectively approach organisms that inhabit cracks, crevices, caves, or overhanging ledges, being greatly limited in their ability to collect specimens of cryptic species, and thus are only adequate for broad observations of conspicuous organisms (Pyle, 2000) Only recently have the deep reef environments between 60 and 150 m (the \"twilight zone\" begun to be examined through diving, using an \"open\" and subsequently \"closed\" circuit mixed gas breathing apparatus (see Pyle, 1998 for a review) The closed circuit underwater apparatus, or \"rebreather\" is now considered the ideal tool for twilight zone exploration, providing as much as 10 12 hrs of underwater autonomy (Pyle, 1996a, 2000) however, rebreathers are extremely expensive, and their use requires extensive training. BULLETIN OF MARINE SCIENCE, VOL. 76, NO. 3, 2005 726 The Brazilian reef fish fauna has remained poorly known for a long time. Only after the mid 1990s, with the growing use of SCUBA by Brazilian ichthyologists, has a significant increase in sampling effort occurred (Moura, 1995; Rocha et al. 1998; Floeter and Gasparini, 2000; Floeter et al. 2001; Rocha and Rosa, 2001; Feitoza et al. 2003) Nevertheless, the Brazilian reef fish community beyond 30 m remains broadly unknown, with the exception of a few commercial species briefly treated by Rocha et al. (1998) who mentioned the necessity of detailed studies on the deep reef fish fauna. Consequently, there is a realm of unexplored reef habitat at depths between about 40 and 150 m. It is expected that this transition zone, from the highly complex and diverse coral reef environments that are fuelled by sunlight, to the relatively barren and perpetually dark abyssal depths where no photosynthesis can occur (Pyle, 1996b) hides a greater number of endemic species than the shallower or deeper regions (Pyle, 1998) Deep reefs off the eastern coast of northeast Brazil (or the \"hump\" of Brazil) are important areas for local fisheries and are being increasingly fished. A 7 yr unpublished study on the Brazilian northeast coast carried out by the authors and other Brazilian ichthyologists has revealed that the deep reefs are one of the last refuges for large commercially exploited reef fishes, such as snappers (Lutjanidae) and groupers (Serranidae) where even globally threatened species such as Lutjanus analis, Lutjanus cyanopterus, and Epinephelus itajara are captured; see Hilton Taylor, 2000. The present study is the first attempt to survey the deep reef ichthyofauna off the Brazilian coast between 35 and 70 m utilizing SCUBA. Despite the limitations of conventional SCUBA at depths beyond 30 m, it was possible to provide a baseline assessment of the deep reef ichthyofauna, including cryptic species, by describing and comparing its fish community with those of other western Atlantic reef sites. MATERIAL AND METHODS STUDY AREA. The study area is located off the eastern coast of northeast Brazil between the States of Rio Grande do Norte (4o59'S) and Pernambuco (7o51'S) (Fig. 1) This is a transition zone where the South Equatorial Current branches to become the northwestward flowing North Brazil Current and the southward flowing Brazil Current (Stramma et al. 1990; Silveira et al. 1994; Leao and Dominguez, 2000) The continental shelf in this area is very narrow (from 22 to 48 km wide according to the hydrographic charts) and shallow, reaching the escarpment between depths of 40 and 80 m (Chaves et al. 1979; Franca, 1979; Knoppers et al. 1999) Deep reef outcrops occur along most of the outer shelf edge, almost always coinciding with the beginning of the shelf break zone (see Kempf et al. 1967; Lana et al. 1996) Fourteen deep reefs were investigated, six of which are over shelf deep reefs and eight shelfedge deep reefs. The water temperature ranged from 23 to 29.5 oC and visibility from 20 to 50 m. Because there are no systematic surveys of the corals, sponges, or algae for the study sites, superficial habitat descriptions are given here to provide only a general idea of the deep reef habitats of the area. The two northernmost over shelf deep reefs surveyed are located about 12 km from the outer shelf edge ranging from 36 to 39 m in depth (Fig. 1B,C) These reefs consist of elongated sandstone outcrops reaching about 3 m from the sandy bottom, forming crevices and small caves. Living corals were present [Montastrea cavernosa (Linnaeus, 1767) Siderastrea stellata Verrill, 1868, Meandrina braziliensis Milne Edwards and Haime, 1848] along with tubular (Aplysina spp. massive, and encrusting sponges. Algae (mainly brown and green) were abundant. The four southernmost over shelf deep reefs are located at about 4 km from the outer shelf edge ranging from 35 to 41 m depth (Fig. 1D,E,I,K) They consist largely of a flat FEITOZA ET AL. BRAZILIAN DEEP REEF FISHES 727 calcareous bottom with gentle inclination and small crevices, surrounded by patches of sand and deposits of algal nodules. Algae (mainly brown and green) and sponges (mainly tubular Aplysina spp. covered most of bottom, with sparse coral growth (Stephanocoenia michelini Milne Edwards and Haime, 1848, Porites branneri Rathbun, 1887, M. braziliensis, S. stellata) Sharp thermoclines were not encountered at the six over shelf sites. The eight shelf edge deep reefs surveyed are distributed along the outer shelf (Fig. 1A,F H,J and L N) at depths of 45 70 m. Two distinct zones were observed at the shelf edge deep reefs: (1) an upper flat zone, with gentle inclination; and (2) a deeper steep zone, composed of carbonatic rock outcrops (Fig. 2) The upper flat zone was similar to the four southernmost over shelf reefs described above. The deeper steep zone was located at the beginning of the escarpment (shelf break) and was marked by an abrupt change on the sea floor relief, from a gently sloping bottom of the upper flat zone to a steeply sloping nearly vertical face, with large rocks and caves. Algae and sponges (tubular, candle, and massive forms) covered most rocky surfaces. Living corals were common along rock ledges, with small colonies of Agaricia fragilis Dana, 1846, P. branneri, and S. stellata, sparse growth of M. braziliensis and Scolymia wellsii Laborel, 1967, and a few small heads of M. cavernosa. Long antipatharians (black corals) were also attached to the rocks. The reef at this depth is very similar to spur and grove formations of outer reefs in Caribbean islands, and probably consists of a drowned coral reef Figure 1. A) Map showing the location of the study area and other South Atlantic sites; B) Dive sites along the study area (letters a n) and the general location of the main shallow reefs. State abbreviations: PE Pernambuco; PB Paraiba; RN Rio Grande do Norte; BA Bahia; ES Espirito Santo; RJ Rio de Janeiro; SP Sao Paulo. BULLETIN OF MARINE SCIENCE, VOL. 76, NO. 3, 2005 728 Figure 2. Spatial distribution of the shelf edge deep reef fishes in water column: Note that figure is not drawn to scale. (U) upper flat zone; (D) deeper steep zone; (S) Surface dwellers; (P) Pelagic species; (B) Bottom dwellers. (1) Clupeidae, Exocoetidae, Belonidae; (2) Scombridae, Coryphaenidae; (3) Carangidae, Sphyrnidae, Balistidae (Canthidermis) Sphyraenidae, Scombridae; (4) Pomacanthidae, Scaridae, Holocentridae, Labridae, Lutjanidae, Serranidae, (Cephalopholis) Balistidae, Acanthuridae, Chaetodontidae, Haemulidae, Malacanthidae; (5) Gobiidae, Congridae, Pomacentrida", "author_names": [ "Bertran M Feitoza", "Ricardo de Souza Rosa", "Luiz A Rocha" ], "corpus_id": 67854665, "doc_id": "67854665", "n_citations": 71, "n_key_citations": 16, "score": 0, "title": "Ecology and Zoogeography of Deepreef Fishes in Northeastern Brazil", "venue": "", "year": 2005 }, { "abstract": "There is increasing evidence that some California oil platforms form important habitats for a number of economically important fishes. We asked to what extent might platforms be important as producers of larvae of several overfished species (bocaccio, Sebastes paucispinis Ayres, 1854 and cowcod, Sebastes levis Eigenmann and Eigenmann, 1889) on a local or regional basis. We compared adult densities and potential larval production of these species at platforms and natural outcrops in California. Densities of mature bocaccio and cowcod were highly variable among survey sites, but were generally very low at both natural reefs and platforms. However, the mean densities for both species were higher around platforms than at natural reefs. Two of the three platforms (Gail and Hidalgo) that harbored mature bocaccio had larger mature individuals than did any natural reef. Platform Gail had by far the highest densities of both mature bocaccio and cowcod of any natural or human made habitat and the potential larval production of both species at Platform Gail was much higher than at any other site surveyed. We estimated the removal of Platform Gail would be the equivalent of removing 12.57 ha of average producing natural habitat in southern California for cowcod or 29.24 ha of average producing natural habitat for bocaccio. These results may have implications for the platform decommissioning process. There are 27 oil and gas platforms off the coast of southern and central California. Located in both state and federal waters, these structures are situated in bottom depths ranging from 11 to 363 m and can have footprints as large as 10,606 m2 (Love et al. 2003) While all of these platforms are currently either pumping oil or gas, or are being used as transfer stations for these products, platforms have a finite economic life span. Once an industrial decision is made to cease oil and gas production, managers must decide what to do with the structure, a process known as decommissioning. Decommissioning is a complex process, involving state and federal agencies, corporate entities, and such stakeholders as recreational and commercial fishermen, and non consumptive users (Schroeder and Love, 2004) Ultimately, a decommissioned platform could be left in place, removed to some point below the sea surface, toppled to lie on the sea floor, or totally removed (Schroeder and Love, 2004) One issue in the decommissioning process is the role that platforms may play as fish habitat. There is increasing evidence that some California platforms form important habitats for many economically important fishes. This is particularly true of the rockfishes (genus Sebastes) that often comprise over 90% of all fishes observed around platforms in southern and central California waters (Love et al. 2003) Platform habitat may serve at least two functions for these fishes. First, the midwaters of many platforms serve as nursery habitat for a suite of rockfishes and other fish species, often harboring higher densities of these species than do nearby natural outcrops (Love et al. 1999; Carr et al. 2003; Love et al. 2003) Compared to most natural reefs, a platform's size, structural complexity, and high vertical profile probably BULLETIN OF MARINE SCIENCE, VOL. 77, NO. 3, 2005 398 provide pelagic juvenile rockfishes and larvae of other species with a relatively strong stimulus to trigger settlement. In addition, most platforms have few large fishes in the midwaters and thus predation on young fishes is likely to be low (Schroeder et al. 2000; Love et al. 2003) Platform bottoms, where the jacket and conductor pipes meet the seafloor, may harbor high densities of subadult and adult fishes, again usually comprised primarily of rockfishes (Love et al. 1999; Carr et al. 2003; Love et al. 2003) The high densities of larger fishes at the platform bottoms are due to both acceptable habitat and because some platforms are rarely fished and thus act as de facto marine reserves (Schroeder and Love, 2002; Love et al. 2003) Off southern California, fishing pressure by both recreational and commercial fishermen on natural outcrop species has been very heavy for many decades (Love et al. 1998, 2002) In particular, the adults of economically important species such as bocaccio (Sebastes paucispinis Ayres, 1854) and cowcod (Sebastes levis Eigenmann and Eigenmann, 1889) are now uncommon or even absent on many natural outcrops in southern California (Love et al. 1998b, 2003; Love and Yoklavich, unpubl. data) Given the depleted state of many rockfish species on natural reefs (seven species have been declared overfished by NOAA Fisheries) and the relative abundance of some of these species on some platforms, we asked to what extent might platforms be important as producers of larvae on a local, or even regional, basis. That is, how important are adult populations of rockfishes on platforms? To help answer that question, we conducted a pilot study that focused on cowcod and bocaccio (Fig. 1) two species declared overfished by NOAA Fisheries and the two overfished species that are most abundant as adults around California platforms. We compared adult densities and potential larval export of these species at both offshore platforms and natural outcrops in central and southern California. A knowledge of the relative importance of these human made structures as fish habitat could play a role in decommissioning decisions. MATERIALS AND METHODS FISH SURVEYS. Between 1995 and 2002, we surveyed platforms sited over a wide range of bottom depths, ranging between 29 and 224 m, and sited from north of Point Arguello to off Long Beach, southern California. Most of our platform surveys were conducted at seven structures (Platforms Irene, Hidalgo, Harvest, Hermosa, Holly, Grace, and Gail) located in the Santa Barbara Channel and Santa Maria Basin. In addition, we surveyed over 80 deeper water outcrops (many in the vicinity of platforms) in waters between 30 and 360 m deep. Most of these deeper water natural sites were visited once, a few were surveyed during as many as 4 yrs and, one outcrop, North Reef near Platform Hidalgo, was sampled annually. We surveyed fish assemblages using the DELTA submersible, a 4.6 m, two person vessel, operated by Delta Oceanographics of Oxnard, California. Aboard the DELTA, we conducted belt transects about 2 m from the substrata, while the submersible maintained a speed of about 0.5 kts. At the platforms, transects were made around the bottom of the platform and around each set of crossbeams to a minimum depth of 20 30 m below the surface (e.g. midwater habitat) The belt transect was also used to sample the shell mounds surrounding the platforms and natural rock outcrops. The shell mounds and outcrops were sampled in consistently the same fashion as the platform method described above. Submersible surveys were conducted during daylight hours between 1 hr after sunrise and 2 hrs before sunset. During each transect, observations were taken from one viewing port on the starboard side of the submersible. An externally mounted hi 8 mm or digital video camera with associated lights filmed the same viewing fields as seen by the observers. The LOVE ET AL. DISTRIBUTION OF BOCACCIO AND COWCOD OFF CALIFORNIA 399 observer identified, counted, and estimated the lengths of all fishes and verbally recorded those data on the video. All fishes within 2 m of the submarine were counted. All fish larger than the size of first maturity were observed within 2 m of the bottom (none were seen in midwater transects) Thus, densities were calculated as fish m 2. Fish lengths were estimated using a pair of parallel lasers mounted on either side of the external video camera. The projected reference points were 20 cm apart and were visible both to the observer and the video camera. An environmental monitoring system aboard the submarine continuously recorded date and time, depth, and altitude of the vessel above the sea floor. The environmental data were overlaid on the original videotape upon completion of each survey. Transect videos were reviewed aboard the research vessel or in the laboratory. Field observations were transcribed into a database. For each fish, we recorded the following information: 1) species (if known) 2) its estimated total length (TL) and 3) in the surveys over natural reefs, the habitat it occupied (e.g. rock, sand, mud, cobble, or boulder) Many years of experience along the Pacific Coast have shown that if the Delta is moving at a constant and slow rate of speed, as in these surveys, there is very little obvious effect on demersal rockfishes (M. Love, V. O'Connell, Alaska Department of Fish and Game, and M. Yoklavich, NOAA Fisheries, pers. obs. Certainly, we noticed virtually no movement at all from most of the fishes in this study as the research submersible passed by. DATA ANALYSES. While our surveys estimated size for most observed fish, we were not able to estimate sex ratios. Cowcod are not sexually dimorphic and it seemed reasonable to assume an equal female to male ratio. Bocaccio are sexually dimorphic and sex ratios of commercial catches are not 1:1 and are related to size. We obtained data to estimate length specific sex ratios for bocaccio from Mark Wilkins (NOAA Fisheries, AFSC, Seattle) in the form of length compositions by sex from the triennial bottom trawl survey conducted by the AFSC. The trawl survey uses finer meshed nets than commercial operations and all captured fish are sampled for length compositions. Commercial operations also discard some fish due to market demand or regulations. Our submersible survey estimated fish size to the nearest 5 cm. Observers were not able to estimate size for a small proportion of fish (0.006 for bocaccio and 0.048 for cowcod) These fish were assumed to be smaller than the size at maturity and not included in the estimates. The trawl survey measured size to the nearest 2 cm. We", "author_names": [ "Milton S Love", "Donna M Schroeder", "William H Lenarz" ], "corpus_id": 31789692, "doc_id": "31789692", "n_citations": 31, "n_key_citations": 2, "score": 0, "title": "DISTRIBUTION OF BOCACCIO SEBASTES PAUCISPINIS AND COWCOD SEBASTES LEVIS AROUND OIL PLATFORMS AND NATURAL OUTCROPS OFF CALIFORNIA WITH IMPLICATIONS FOR LARVAL PRODUCTION", "venue": "", "year": 2005 }, { "abstract": "Auteur(s) Jean Benard Le Bulletin du Cancer s'est souvent fait l'echo du role des proteines BRCA1 et cycline D1 dans la carcinogenese mammaire [1 4] L'equipe de Richard Pestell de l'universite de Georgetown, a Washington DC, publie dans le numero du 1er aout 2005 de Cancer Research, un travail qui associe sans ambiguite les deux proteines dans un mecanisme commun la cycline D1 antagonise la repression qu'exerce BRCA1 sur l'activite du recepteur a a l'oestradiol (REa) [4] BRCA1, gene de susceptibilite au cancer du sein, code une proteine de 220 kDa qui inhibe in vitro et in vivo la croissance des cellules cancereuses mammaires. Par la pluralite de ses fonctions, BRCA1 joue vraiment pour la cellule epitheliale a impregnation oestrogenique le role qu'a Civa, la deesse aux dix bras, sur l'univers Cette proteine cumule en effet les fonctions, non seulement de suppresseur de tumeur specifique du tissu epithelial mammaire, mais aussi de coordinateur de la reparation des dommages de l'ADN et de regulateur transcriptionnel. En se fixant aux facteurs de transcription p53, myc ou ZBRK1, elle participe a la regulation du cycle cellulaire au niveau de ses differents points de controle. On percoit les effets deleteres des mutations du gene BRCA1 sur toutes ces fonctions. La specificite d'action de BRCA1 vis a vis du tissu mammaire a conduit a proposer un modele ou la proteine BRCA1 agirait comme proteine suppresseur de tumeur en reprimant la signalisation induite par le recepteur a a l'oestradiol (REa) et ce tres precocement dans la carcinogenese mammaire et la dedifferenciation [5] Ce modele s'est trouve etaye par un ensemble de donnees experimentales montrant que BRCA1 1) sur des lignees de cancer mammaire humain, inhibe les effets biologiques de la fixation du 17b oestradiol (E2) sur son recepteur REa en interagissant physiquement avec lui [6] 2) sur des lignees humaines non mammaires, inhibe l'activite basale du REa et reprime les genes induits en reponse a E2 (pS2 par exemple) Quant a la cycline D1, des experiences de transgenese ont montre que, chez la souris, elle induit une carcinogenese mammaire a contrario, des souris nullizygotes pour la cycline D1 ne developpent pas de tumeur mammaire, classiquement induite par l'hyperexpression d'erb B2, voire une mutation de Ras [7] Rappelons que le gene cycline D1 code une holoenzyme qui, en s'associant avec la kinase cdk4, phosphoryle la proteine suppresseur de tumeur Rb et l'inactive. Derniere donnee rationnelle importante, l'hyperexpression de la cycline D1, qui concerne 30 a 40 des tumeurs mammaires, est associee a un mauvais pronostic lorsque la tumeur exprime REa [8] Ces donnees inciterent, tout naturellement, l'equipe de Pestell [4] a rechercher un mecanisme de regulation de l'activite de REa reliant les proteines BRCA1 et cycline D1. Dans un premier temps Wang et al. [4] ont mesure, sur la lignee T47D positive pour REa les effets des deux proteines sur l'expression du gene PS2, un gene induit par un ajout de 17b estradiol la transfection du gene BRCA1 entraine la repression de l'activite de REa, cette activite etant selectivement restauree apres transfection du gene cycline D1. Les chercheurs ont voulu determiner ensuite les domaines d'interaction des deux proteines avec le REa. Des experiences d'immunoprecipitations suivies de western blot montrent clairement l'existence de complexes cycline D1 REa et BRCA1 REa, et ce dans des conditions physiologiques ou s'exerce l'activite du recepteur aux oetrogenes. L'utilisation de mutants positionnels a permis de preciser que la fixation de cycline D1 se fait dans la partie C terminale du REa (residus 282 a 378) L'utilisation de proteines de fusion couplees a des experiences de pull down experiences in vitro consistant en une retention sur une colonne d'affinite suivie d'une elution par competiteur specifique a conduit a constater que les proteines cycline D1 et BRCA1 se fixent sur le meme domaine du REa. Un nouveau domaine de cycline D1, cense former une structure en helice boucle helice, s'avere necessaire pour sa fixation au REa, ainsi que pour sauvegarder la repression exercee par BRCA1 sur l'activite de REa. Des experiences d'immunoprecipitation de chromatine montrent que, dans le contexte de la structure chromatinienne des cellules MCF7, E2 induit l'expression de REa et facilite aussi le recrutement de la cycline D1 a un element de reponse a E2 (sequence ERE pour E2 Responsive Element) Et l'inhibition qu'exerce BRCA1 sur le recrutement de REa s'exerce justement au niveau de ce meme ERE [4] Notons que les taux de BRCA1 capables d'inhiber la signalisation REa dans ces experiences sont du meme ordre de grandeur que ceux associes au developpement mammaire lors de la puberte et la grossesse chez la femme, deux phases physiologiques ou des pics hormonaux sont atteints et ou BRCA1 jouerait pleinement son role de suppresseur de tumeur. Les auteurs n'ont pas manque de placer leur travail dans la perspective epidemiologique des cancers mammaires a BRCA1 mutes qui sont, en general, RE negatifs et presentent un phenotype epithelial basal different des tumeurs RE positives en depit d'une signalisation en RE deficiente, ces cellules epitheliomateuses inactivees pour BRCA1 peuvent connaitre une activation de RE independante de la fixation de son ligand. A l'inverse, frequemment, les cancers mammaires sporadiques sont RE positifs et manifestent une expression reduite de BRCA1. Qu'il s'agisse de tumeurs se developpant chez des femmes porteuses de mutation BRCA1, ou de formes sporadiques, ces donnees suggerent que la repression qu'exerce BRCA1 sur la fonction REa est un evenement important lors de la carcinogenese mammaire. Ces travaux demontrent, pour la premiere fois, qu'une proteine cle du controle du cycle cellulaire, la cycline D1, interagit a un niveau moleculaire avec la proteine BRCA1 pour s'opposer a la fonction de suppresseur de tumeur qu'elle exerce non seulement sur la machinerie de la reparation genomique mais aussi sur celle de la proliferation cellulaire. Ainsi, en interagissant physiquement avec les deux grandes familles de genes du cancer les gardiens et les soignants du genome [9] la proteine BRCA1 joue t elle un role cle dans la carcinogenese mammaire References 1. Pujol P, This P, Noruzinia M, Stoppa Lyonnet D, Maudelonde T. Les formes hereditaires de cancer du sein liees a BRCA1 et BRCA2 sont elles sensibles aux oestrogenes Bull Cancer 2004 91 583 91. 2. Benard J, Guinebretiere JM. Et si BRCA1 regulait la reponse cellulaire aux oestrogenes Bull Cancer 1999 86 608. 3. Larsen CJ. Cycline D1 and cancer du sein la nouvelle de l'ete 2001. Bull Cancer 2001 88 717 8. 4. Wang C. et al. Cyclin D1 antagonizes BRCA1 repression of estrogen receptor activity. Cancer Res 2005 65 6557 67. 5. Hilakivi Clarke L. Estrogens, BRCA1, and breast cancer. Cancer Res 2000 60 4993 5001. 6. Fan S et al. Role of direct interaction in BRCA1 inhibition of estrogen receptor activity. Oncogene 2001 20 77 87. 7. Yu Q, et al. Specific protection against breast cancers by cyclin D1 ablation. Nature 2001 411 1017 21 8. Kenny F, et al. Overexpression of cyclin D1messenger RNA predicts for poor prognosis in estrogen receptor positive breast cancer. Clin Cancer Res 1999 5 2069 76. 9. Kinzler K, Vogelstein B. Cancer suceptibility genes. gatekeepers and caretakers. Nature 1997 386 761 3.", "author_names": [ "Jean Benard" ], "corpus_id": 73241023, "doc_id": "73241023", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Carcinogenese mammaire quand cycline D1 et BRCA1 se disputent le recepteur aux estrogenes", "venue": "", "year": 2005 }, { "abstract": "A short term field experiment was conducted to investigate the effects of plant cover removal on temporal trends of species richness and abundance of the macrobenthic community in a subtropical salt marsh in Paranagua Bay (southeastern Brazil) Plant cover was removed to test the hypothesis that habitat complexity plays an important role in structuring infaunal and epifaunal assemblages. Habitat complexity for the macrofauna assemblages, above and below the sediment surface, was greatly influenced by Spartina alterniflora Loisel, 1807 leaves, culms, roots, and rhizomes. The response of infaunal or epifaunal species depended on their ability to discriminate between vegetated or unvegetated habitats. Habitat specialists from the epifauna forms closely associated with plant structures, such as the gastropod Neritina virginea (Linnaeus, 1758) the isopod Sphaeromopsis mourei (Loyola and Silva, 1960) and an unidentified gammarid species were clearly affected by plant removal, whereas the habitat generalist epifaunal Kalliapseudes schubarti ManeGarzon, 1969 (Tanaidacea) did not respond to it. Relative abundances of habitat specialist infauna, such as the polychaetes Isolda pulchella Muller, 1858 and Nereis oligohalina Rioja, 1946, and habitat generalist infauna, such as the polychaetes Laeonereis acuta Treadwell, 1923 and Capitella sp. did not change significantly after plant removal. Abundance of local macrobenthic species was significantly correlated to rainfall and tended to be reduced after intense freshwater inputs in the summer. Changes in local macrobenthic associations were the result of interactive effects of plant biomass and sediment changes on small spatial scales, and physical impacts of summer freshwater runoff on large spatial scales. Habitat complexity regulates plant and animal communities at different spatial and temporal scales. Plant cover is one of the main sources of spatial heterogeneity in tropical and subtropical tidal flats, since the distribution, density, and architecture of mangrove and saltmarsh plants can heavily influence the abundance and diversity of benthic invertebrates (Costa and Davis, 1992; Lana et al. 1997) Both grasses and shrubs from salt marshes or trees from mangrove stands are presumed to stabilize sediments and to provide food and shelter from predators for the benthic fauna (Micheli, 1996; Sarda et al. 1998; Schrijvers et al. 1998) Conversely, unvegetated tidal flats are presumed to sustain less diversified and abundant macrobenthic associations. However, even those apparently homogeneous intertidal areas are full of biogenic structures and microtopographical features, which can introduce spatial heterogeneity (Levin et al. 1998; Blanchard and Bourget, 1999) Wetlands are a source of coastal protection and are frequently advocated for practical environmental restoration. The potential value of salt marshes for conservation is generally recognized, at least in terms of the diversity of plants and animals associated with them (Boorman, 1999) However, both natural and manmade disturbances may lead to vegetation loss in salt marshes. Natural disturbance can result from wrack deposition, grazing, and storms; whereas cultivation, restoration, reclamation, landfill, embankment, earthwork, and clipping for fishing activities are the more evident human impacts on the salt marshes. The effects of aquatic vegetation BULLETIN OF MARINE SCIENCE, VOL. 77, NO. 1, 2005 2 losses on invertebrates are better known in seagrass habitats but still poorly understood in salt marshes. There is an impressive literature on the fauna of salt marshes, mainly in the northern hemisphere. This is not the case, however, for the fauna of tropical or subtropical marshes associated with or out competed by mangrove woodland. Studies on macrobenthic species from intertidal flats of Paranagua Bay (southeastern Brazil) have indicated that plant architecture, detrital input, and predation pressure play a major role in structuring epifaunal communities (Lana and Guiss, 1992) Infaunal abundance is related to below ground plant biomass, which provides refuge to organisms or physical support to tubes. Seasonal changes in Spartina alterniflora Louisel, 1807 biomass, with typical cycles of below ground storage in late winter and spring followed by aerial translocation in summer, influence both the abundance (Lana and Guiss, 1991) and reproductive strategies (Pagliosa and Lana, 2000) of local macrofauna. The more exposed the tidal flats, the more faunal numbers differ between vegetated and unvegetated sediments (Netto and Lana, 1996, 1999; Lana et al. 1997) These complex plant animal relationships are also affected by freshwater runoff during spring and summer months (Pagliosa, 1997) Experimental approaches are an useful tool to quantitatively and qualitatively assess the influence of environmental disturbance on benthic fauna. Field experiments are widely used to assess the role of habitat complexity in influencing the structure and function of soft sediment communities. Experimental removal of plant cover, followed by the analysis of faunal trends, has provided insight on the putative importance of such regulating mechanisms. However, the effects of artifacts arising from experimental investigations in soft sediments should not be minimized (Peterson and Black, 1994; Skilleter, 1996) This study was undertaken to analyze the effects of plant cover on short term trends in species richness and abundance of macrobenthic associations in an intertidal flat of Paranagua Bay. Plant cover was removed to test the hypothesis that habitat complexity plays an important role in structuring infaunal and epifaunal associations. MATERIAL AND METHODS EXPERIMENTAL SITE. Paranagua Bay (25o 30'S, 48o 25'W) is one of the least polluted estuarine systems in southeastern Brazil (Fig. 1) The bay has a well developed high energy euhaline sector (average salinity values close to or higher than 30) with extensive tidal flats, which can reach a width of up to 2 km. Water circulation in Paranagua Bay is driven mainly by river runoff and tidal forcing, with semidiurnal tide and diurnal inequalities. Strong nonlinear interactions allow for the formation of up to six high and low tides per day during neap cycles, when tidal heights are around 80% of the height of spring tides. Wave action, mainly originating from the southeast, is only important at the bay mouth, but winds may produce locally generated surface waves when blowing in the east west direction (Lana et al. 2000) Paranagua Bay is surrounded by a diverse set of natural habitats, which include mangrove swamps, salt marshes, and extensive unvegetated flats. The region as a whole is a transitional zone for tropical mangroves, which begin to be replaced by temperate salt marshes. Pure stands of S. alterniflora colonize well sorted sand sediments in the euhaline sector, as narrow discontinuous belts in front of mangrove woodland (Lana et al. 1991) The field experiment was conducted at an intertidal flat in Rasa da Cotinga Island (25deg31.95'S, 48deg23.99'W) near the outlet of Paranagua Bay (Fig. 1) The local flat has a width of about 600 m from the salt marsh belt to the lower spring tide level. The upper region, colonized by Spartina, is steeper (0.45 m over 10 m) followed by a gentler slope (0.55 m over 590 m) Local PAGLIOSA AND LANA: IMPACT OF PLANT COVER REMOVAL ON BENTHIC FAUNA 3 sediments are mainly well sorted fine sands, with low organic content in the upper region and well developed aggregates of shell fragments in the lower region. EXPERIMENTAL PROCEDURE AND DESIGN. Experiments were conducted from January to April 1995. We established two experimental sites, made up of three treatments each, hereafter called unvegetated, vegetated, and cleared plots. Natural differences between sites were slightly related to site elevation, density, and height of shoots. Plots were 14 m2 (2 x 7 m) and were separated by ca. 5 m from each other. At each cleared plot, leaves and culms of S. alterniflora were clipped at ground level and removed from the experimental site together with attached epibenthic species. One additional plant cutting and removal was carried out 1 wk later; growth or regeneration of leaves and culms were not a problem thereafter. From January to April 1995 each plot was sampled every 2 wks (seven sampling dates, including the setup of the experiment when only vegetated and unvegetated habitats were sampled) At each plot, five random biological core samples were taken with a PVC core tube, 15 cm in height and 15 cm wide (0.02 m2 of area) and one sediment sample was taken with a PVC sampler, 5 cm in height and 10 cm wide. We estimated that the removal of biological and sedimentological samples did not affect more than 20% of total plot area throughout the experiment. The bulk samples were fixed in 10% formalin, dyed with Bengal red (0.0005 g ml 1) and sieved through a 500 mm mesh. Macrofauna were preserved in 70% alcohol. Below ground material, identified as living plant biomass (whitish rhizomes and roots) and detritus (organic debris and shells) was estimated by drying to constant weight at 75 oC. The water content of the sediment was determined as weight loss after drying. Sediment organic content was calculated after burning subsamples at 550 oC for 1 hr, and carbonate content through acidification (HCl at 10% Sediments were analyzed, using the pipette and dry sieve method (Carver, 1970) Salinity and temperature of the surface sediment layer were recorded in the field. Daily rain values for the period of the experiment were obtained from a meteorological station situated at the Paranagua Harbour (Fig. 1) DATA ANALYSES. Data analyses were applied to a frequency matrix of the 16 top taxa or species in terms of abundance (98% of total) Differences in the structure of assemblages Figure 1. Study site (l) in Paranagua Bay, southeastern coast of Brazil", "author_names": [ "Paulo R Pagliosa", "Paulo da Cunha Lana" ], "corpus_id": 199554565, "doc_id": "199554565", "n_citations": 10, "n_key_citations": 3, "score": 0, "title": "IMPACT OF PLANT COVER REMOVAL ON MACROBENTHIC COMMUNITY STRUCTURE OF A SUBTROPICAL SALT MARSH", "venue": "", "year": 2005 }, { "abstract": "Improving audience involvement in media production enhances the democratization potential within a community and enhances the capacity building potential within that community. Both democratization and capacity building have been identified as factors which enhance a community's ability to thrive. While profitability and return on investment (ROI) are legitimate goals for media organisations insofar as they allow and encourage audience involvement, these goals must remain subordinate to the goal of democratization, since without that key element, the environment which maintains the media disappears. A formula is proposed whereby media owners, workers and audiences can fine tune their relationship to enhance financial as well as community outcomes. 1 John Cokley PhD is a lecturer in journalism at the University of Queensland. [email protected] Cokley, John (2005) The financial importance of audience involvement for media survival Journalism Education Association Conference 2005 Page 2 of 20 2 Introduction Statement of the problem Newspaper organisations worldwide are experiencing a general downturn in circulation figures, which reflect lower sales and a lower share of the media market. In the United States, observers (Journalism.org 2005, n.p. note that 2005 was merely the latest in a 30 year circulation decline for daily newspapers, and that the decline was deepening. The impact was so severe that a major scandal erupted involving four metros who reportedly had been inflating their circulation numbers (Journalism.org 2005, n.p) Loyalty in the audience suffered at the same time: only 60 percent of people said they read a daily newspaper \"regularly\" compared with the average of 70 percent during the 1990s (Journalism.org 2005) The story was slightly less alarming in the UK (see [email protected] 2005; and Newspaper Marketing Agency 2005) but dailies and weeklies there each still dropped a cumulative 2 million adult readers in the period 1999 2004. More damagingly, national newspapers advertising revenues had decreased in the UK from PS2252 million in 2000 to PS1980 million in 2004 (Newspaper Marketing Agency 2005) A straw poll of other newspaper markets (Publicitas.com 2005) indicated a marked general decline among German newspaper reader numbers and an across the board and steep decline recorded by each of the top 10 German magazines; in Italy, seven national or semi national newspapers increased their circulations while Cokley, John (2005) The financial importance of audience involvement for media survival Journalism Education Association Conference 2005 Page 3 of 20 3 six lost ground and of the 19 magazines surveyed, 17 suffered circulation declines and the remaining two recorded increases; in New Zealand, however, five of the eight newspapers surveyed showed increased circulation figures, one broke even and one fell. The figures for the comparatively small market of Australia show a 159,000 copy circulation decline for national and metropolitan mastheads during the 12 months to February 2005 (Kirkpatrick 2005, p.7) Among 12 metropolitan and national dailies surveyed (Kirkpatrick 2005, p. 8) nine showed a drop in Monday Friday readership of between 0.2 and 3.6 percent, one held steady and only two showed gains, one of 1.3 percent, the other of 4.4 percent. Of the Saturday editions, only three increased circulation (by 0.1 and 0.3 percent) while the rest fell, by rates between 0.2 percent and 5.9 percent. Among the Sunday editions, five rose and six fell. More weekly magazine readership numbers fell than rose and monthly magazine figures show five losing ground and five gaining (Publicitas.com 2005) However, among 36 regional dailies surveyed (Kirkpatrick 2005, p. 9) only 13 recorded circulation losses, 21 recorded increases and two were not available. Cokley, John (2005) The financial importance of audience involvement for media survival Journalism Education Association Conference 2005 Page 4 of 20 4 Purpose of this paper This paper examines one of the causes of newspaper circulation decline a decrease in audience appeal and discusses strategies being employed by publishers to increase or at least maintain that appeal. It argues for a new, more effective strategy. Methodology The methodology employed for data collection in this paper is literature review and data analysis. The problem is then attacked by discussing certain drivers and inhibitors of audience appeal, and applying theoretical concepts to the data in order to arrive at a new theoretical construct. The novel feature of this work is that a mathematical formula is proposed as a template for publishers, journalists and audiences to apply to their news communication processes in order to enhance the communications experience for each. It is suggested that a mathematical formula is easy for journalists to understand and to implement, and is also easy to adapt and develop as new research is added. It is proposed that enhancing the communications process will, in the long run, enhance the financial viability of the publications which adopt this formula. Cokley, John (2005) The financial importance of audience involvement for media survival Journalism Education Association Conference 2005 Page 5 of 20 5 The data Drivers and inhibitors of circulation 1. Inhibitors A strong inhibitor of appeal and thus sales and circulation is that newspapers are at the low end of interactivity along the spectrum of news media delivery options, based on Heeter (in Kenney et al 2000, n.p. Arguably, television is next, by virtue of the Big Brother voting phenomenon and the resuscitation of \"The Worm\" (The Age 2005) but certainly radio is more interactive than both, based on its use of talk back and the frequency of its news bulletins. Online, for now, occupies the high end of interactivity on this spectrum, but the word \"online\" hides a multitude of mediums, including email, HTML, XML, PHP and a range of appliance based delivery options such as SMS. Another inhibitor of appeal is the perception, based on the Herman Chomsky propaganda model (1988) that news organisations are large, amorphous organisations filled with staff intent on promulgating their own agenda (Anticapitaliste 2005, n.p. Louw (2001, p. 156) and others (Cokley 2005) note that news making in newsrooms is constrained by hegemonic dominance, created through the staffing practices (recruitment, promotions and dismissals) employed within these sites and by decision making concerning rules, procedures and the configuration of technology within these sites: There is no need for directives concerning which discourses should be favoured because good staffing decisions (from CEO downwards) can be Cokley, John (2005) The financial importance of audience involvement for media survival Journalism Education Association Conference 2005 Page 6 of 20 6 relied on to create self policing mechanisms (through staff 'cloning' Discourses serving the hegemonically dominant will be adhered to because staff cloning will ensure 'appropriate' gatekeepers are in position (Louw 2001, p. 157) As a counter to this but in part only the major rural and regional publishers in Australia Rural Press Ltd and APN News and Media (formerly known as Australian Provincial Newspapers) have emphasised the \"local\" nature of their products and seem to have benefited from that strategy. Rural Press (2005, p. 7) which publishes 160 daily, weekly and monthly metropolitan and regional titles across rural Australia, announced a 21.4 percent increase in net profit after tax for the year to June 2005. According to the company annual report (2005, p. 11) \"community involvement and the quality and relevance of editorial content were fundamental to the successful year\" The company has adopted the slogan \"Life is Local\" APN News and Media publishes 23 regional daily titles and more than 100 non daily titles and reported a 17 per cent increase in profits for the six months to the end of June 2005 (APN 2005, p. 1) to a total of $66 million. According to a company statement (APN 2005, p. 2) regional newspapers in Australia and New Zealand accounted for a large slice of that increase, contributing the second highest profit increase for the group, which also includes capital city newspapers in New Zealand, radio, outdoor, other print and corporate media. Other print and corporate media recorded losses; radio recorded an increase which nearly Cokley, John (2005) The financial importance of audience involvement for media survival Journalism Education Association Conference 2005 Page 7 of 20 7 equaled all newspaper profit growth in both Australian and New Zealand markets. However, as the company report to the market shows, profit was directly related to advertising revenue, not newspaper circulation (APN 2005, p. 3) employment and real estate advertising drive profitability, while circulation rose by less than 1 per cent across the period. The highest circulation rise across the group was recorded in the New South Wales regional centre of Grafton (3.4 per cent) while New Zealand titles did not cross the 2 per cent threshold. This circulation growth roughly matched the Australian population growth for the period (ABS 2005, n.p) but in APN's key Australian market, Queensland, the circulation increase was only half the 2 per cent population increase (Queensland Government 2005, p. 1) indicating a net decline in market penetration. Drivers Circulation strategies Circulation stagnation is often regarded by journalists and proprietors as a problem which is fixed by changes to format and content, since these are regarded as the keys to \"quality\" (Campos 2005, p. 53) Thus, some newspaper editors will introduce \"more choices\" (Campos 2005, p. 56) in new daily or weekly supplements, or change from broadsheet to tabloid, or introduce giveaway publications. Cokley, John (2005) The financial importance of audience involvement for media su", "author_names": [ "John D Cokley" ], "corpus_id": 153469088, "doc_id": "153469088", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "The financial importance of audience involvement for media survival", "venue": "", "year": 2005 }, { "abstract": "ammalian predators were excluded from given sections of a re created tallgrass prairie in Northeastern Illinois. The effects of this exclusion were measured through observation and sampling of macroinvertebrate species. Results were taken from the area where mammalian predators were excluded after a 5 year period of time and also from a random area two meters away which served as a control. The pH and temperature measurements of the soil were also taken at each site, and an inventory of plants in the area was recorded. Species assemblages of macroinvertebrates and flora were more similar among the 7 exclusion sites than among the 7 control sites. Predator exclusion can explain this observation where the macroinvetebrate communities in enclosures shifted in a common way which affected the flora via grazing. Alternatively, the observation may reflect bias from the original re creation efforts. Introduction Because species do no exist in isolation but, rather, are embedded in more complex interactions, the affect which mammalian predators have upon the dynamics and biodiversity of macroinvertebrate communities can aid in understanding and learning about re created systems and their processes (Bonsall, 2003) If predators choose to prey upon only one species of macroinvertebrates, then that predator can dramatically change the age distribution of that species. Conversely, if the predator eats only the reproducing members of a population, the population will decrease greatly come the next period of birth. Through these feeding habits, the predators then can decrease the survivorship of certain prey species and also change vital rates of reproduction and growth (Nakaoka, 2000) When the effects of predation upon the hard clam Mercenaria mercenaria were studied in the estuaries of North Carolina, it was shown that growth rates were lower in habitats where predation rates were higher (Nakaoka, 2000) If a population is preyed upon for a long period, its population can severely decrease. As the prey population decreases, the predation rate also decreases because the abundance of that prey species becomes rare in comparison to other prey species. Because the decrease in prey population equals less food for the predator, the predator will divert attention to other, more abundant prey species (Khan, et al 2004) Because predators tend to prey more upon those species which are abundant and small in size, the macroinvertebrate community becomes key in understanding life in re created systems such as the tallgrass prairie (Khan and Ghaleb 2002) Ecological processes of the prairie can M 1 Kopjo: Biodiversity of the Macroinvertebrate Community in a Re created Tallgrass Prairie Published by DigitalCommons@COD, 2005 58 often be connected to the activities of insects. Avian and mammalian predators depend upon the abundance and location of food sources, including insects, to determine where to breed. Plant distribution is affected by insect pollination, seed predation, and grazing (Costello, 1969) If not controlled, herbivores can severely disturb the plant community. Prey species can also affect the availability of flora because, in addition to ingesting macroinvertebrates, many species also ingest plants. The gray fox, Urocyon cinereoargenteus, has been examined and found to ingest plants, including various nuts and berries, in addition to the macroinvertebrates they regularly consume (Bauer, 1988) Consequently, factors that regulate macroinvertebrate populations help in understanding the stability and management of re created systems. A re created system was examined in the paper to determine how the biodiversity of the macroinvertebrate community is affected by the exclusion of mammalian predators. Based upon knowledge of predator prey relationships, predictions of this study conclude that there will exist some sort of effect on the macroinvertebrate community within the re created tallgrass prairie of Northeastern Illinois. As much of the original tallgrass prairie has been destroyed, endangering many species, the understanding of community dynamics gained in this study was presumed helpful in preserving the remnant diversity in re created systems (Madson, 1993) Methods A search for specimens was conducted in September 2004 in the 15 ha Russel Kirt recreated tallgrass prairie, which began in 1985. Kirt (1996) provides description of the flora community of the prairie. The seven 2m x 2m enclosures which were specifically studied were established five years ago and are scattered along the perimeter of a retention pond which is also a part of the re created tallgrass prairie. Galvanized chicken wire was buried to a depth of 15 cm and extended to a high of 30 cm. The 5 mm mesh size acts to prevent invasion by larger mammalian predators including shrews, fox, and raccoons. Controls were selected based on being within 2 m of the enclosures and along the same approximate slope proceeding to the retention pond. Macroinvertebrates were inventoried from the enclosures in which mammalian predators were excluded and also from the controls two meters away according to morphotype as well as to the lowest taxonomic level possible. At each area from which macroinvertebrates were collected, pH level and temperature of soil was recorded using an Aquaterr Temp 200 meter (Aquaterr Instruments, Costa Mesa, CA) Also, inventories were done on all flora seen in both enclosed and controls. Assemblage structures of the macroinvertebrate communities and floral communities were summarized using correspondence analysis. The ordination technique offers to reduce community data to coordinates on a multidimensional plane. Only the first two dimensions were considered here as they explain most of the variance in data. Communities which are more similar should have coordinates that are closer together than communities which are less similar. Results Lists of macroinvertebrates and flora can be obtained by contacting College of DuPage. Table 1 provides the first two dimensional coordinates from the correspondence analysis of the macroinvertebrate communities and floral communities, in addition to the soil temperature and moisture at 10cm. Figures 1 and 2 provide a plot of ordinated data of the macroinvertebrate and flora communities using the first two dimensions of correspondence analysis, respectively. 2 ESSAI, Vol. 3 [2005] Art. 18 http:/dc.cod.edu/essai/vol3/iss1/18 59 Ordinated assemblance structures of macroinvertebrates and flora communities were more similar in enclosures than controls. Discussion Explanations to the similar assemblages of macroinvertebrates and flora among controls include the thought that human involvement when first creating the enclosures determined which plants, and consequently which species of macroinvertebrates, were to be found in each area. Alternatively, the exclusion of mammalian predators may have caused the succession sequence of macroinvertebrates among enclosures, which was propagated to the plant community by grazing pressures. It also must be taken into consideration that flora species may be similar as a result of excluding mammalian consumers from the enclosed areas. If consumers are unable to enter the enclosed areas, then certain plants which would otherwise be consumed are allowed to flourish. This would account for similarities in flora species not only in enclosures but also in the control areas. The flora species in the control areas would be more alike because they were equally available to predators. Macroinvertebrate species in controls would also then be more alike because the flora species upon which they depend would be similar. The same logic holds true for the macroinvertebrate species in the enclosures. If the same macroinvertebrates were found, then the same species of mammalian predators may have been found preying upon the species. Additionally, higher variance among controls in macroinvertebrate and floral assemblages may reflect uneven distribution of mammalian predators in the re created system. However, neither the abundance of predators in enclosures nor control areas was observed. Each track of hypothesis needs to be further scrutinized to determine the effects of excluded mammalian predators on the macroinvertebrate communities of the re created tallgrass prairie. Works Cited Bauer, E. 1988. Predators of North America. Grolier Books, Latham, NY. Bonsall, M.B. 2003. The role of variability and risk on the persistence of a shared enemy, predator prey assemblages. Journal of Theoretical Biology 221: 193 204. Costello, D. F. 1969. The Prairie World. Crowell Company, New York, NY. Khan, Q.J.A. A. Balakrishnan, and C. G. Wake, 2004. Analysis of a predator prey system with predator switching. Bulletin of Mathematical Biology 66: 109 123. Khan, Q.J. A. and A.F. Ghaleb, 2002. A study of prey predator relations for mammals. Journal of Theoretical Biology 223: 171 178. Kirt, R. R. 1996. A nine year assessment of successional trends in prairie plantings using seed broadcast and seedling transplant methods, p. 144 153. In: C. Warwick (ed. Fifteenth North American Prairie Conference, The Natural Areas Association, Bend, OR. Madson, J. 1993. Tallgrass Prairie: A Nature Conservancy Book. Falcon P, Helena. Nakaoka, M. 2000. Nonlethal effects of predators on prey populations: predator mediated change in bivalve growth. Ecology 81: 1031. 3 Kopjo: Biodiversity of the Macroinvertebrate Community in a Re created Tallgrass Prairie Published by DigitalCommons@COD, 2005 60 Table 1. First two dimensional coordinates from correspondence analysis (CA) of the macroinvertebrate communities and floral communities, soil temperature at 10 cm depth, and soil moisture at 10 cm depth according to sample site. Symbols: Ei enclosure site i and Ci control site i. ________________________________________________________________ Site Macroinvertebrate Soil Soil Floral community temperature moisture community coordin", "author_names": [ "Valentine Kopjo" ], "corpus_id": 34061986, "doc_id": "34061986", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Biodiversity of the Macroinvertebrate Community in a Re created Tallgrass Prairie as Affected by Exclusion of Mammalian Predators", "venue": "", "year": 2005 }, { "abstract": "Propagation of S. stuckyi was found to be possible when cuttings of juvenile leaves were used without any hormonal or surgical treatments. Anatomical examinations of the tissues where root formation took place indicated no distinctive differences between juvenile and adult leaves. Production of marketable plants is slow and best carried out in tropical or subtropical areas. INTRODUCTION Sansevieria stuckyi is a succulent perennial originating in the mountains of Zimbabwe and has been known to botanists and botanical gardens since late 1700s (Brown, 1915) but never produced commercially as an ornamental in pots. S. stuckyi belongs to the monocotyledonous family Dracaenaceae and other members of the genus notably S. trifasciata have been produced and grown in nurseries and homes for centuries. The genus comprises some 60 or 80 species (Eggeli, 1994; Chahinian, 2001) depending on which authority one wishes to follow. Most species are found in dry savannas of east Africa. S. stuckyi has two life forms: juvenile and adult. The juvenile leaves are flat to involute, bending grey green with dark green cross stripes. The juvenile phase lasts from four to six years depending on climatic conditions (Chahinian, 2001) The adult plants (Fig. 1) have large rhizomes, thick almost cylindrical, dark green leaves of 2 3 cm in diameter and up to 2 m length in irregular rosettes; the leaves are very fibrous and coated with thick layers of wax. Flowers are rarely if ever seen in cultivation, in Nature the insignificant flowers appear at the basal side of the leaf rosettes. The proposed utilization of S. stuckyi as a novel potted plant is seen as a catering to the trend of easy maintenance, sculptural plants (Noack, 2003) for banks, bureaucrats and bachelors. For use as a potted plant efficient propagation is essential. S. stuckyi can be propagated by division of the rhizomes but this is slow and requires large plants. The propagation of S. trifasciata is generally done by leaf cuttings or sections of leaves and it was decided to examine the possibility of using the same method for S. stuckyi. One of the main problems according to Brown (1915) is the extremely slow rooting of cuttings. In other species it has repeatedly been shown that there are marked differences between cuttings taken from juvenile and adult tissues or organs (eg. Davies et al. 1982, with Ficus pumila and Hackett, 1988, with Hedera helix) MATERIALS AND METHODS As stock plants were used adult plants of Sansevieria stuckyi Godefroy Lebeuf that had been grown in the botanical collection of Copenhagen University for about 50 years. The origin of these plants was a collection of seeds received in exchange from the botanical garden of Abo, Finland, but more details are unavailable. One of these plants has since been multiplied as a clone. They have been grown in a greenhouse with 17 to 26 C RH 70% and supplemental light during the winter months. Adult leaves were cut in 10 cm sections. Juvenile leaves 7 10 cm long were cut at the base from regenerated adult cuttings (Fig. 2) Cuttings were treated with Floramon rooting powder (0.1 or 0.4% NAA) For the adult cuttings a further treatment consisted of wounding with 3 cuts 3 cm from the base up. The cuttings were placed with one cutting per 9 cm pot filled with Vermiculite. The pots were randomly arranged on a bottom 259 Proc. V IS on New Flor. Crops Eds. A.F.C. Tombolato and G.M. Dias Tagliacozzo Acta Hort. 683, ISHS 2005 heated (20C) greenhouse bench, covered for the first month with shading cloth. Later the shade was removed and supplementary light (400W m) given for 8 h daily. Air temperature was 25C day and night. A drench with Octave was given after two weeks for control of fungal diseases. Watering was manual with tap water until two moths then with a standard greenhouse fertigation at pH 6 and EC of 1. The experiment was repeated. Number of surviving cutting was recorded throughout the experiments. At selected dates the cuttings were removed from the medium and roots and shoots were counted. In a separate experiment cuttings were placed in styrofoam plates floating on aerated weak nutrient solutions in 40 liter white plastic boxes. These boxes were in the same greenhouse as the pot experiments. Statistical treatment of rooting and shoot formation data were done with KruskalWallis one way analysis and Dunn's test in the program Sigma Stat. RESULTS Survival of the cuttings was best in control and inferior with auxin treatments and wounding (Table 1) Rooting of the surviving cuttings was generally unaffected by the auxin treatments. After 39 days 80 to 90 of the juvenile cuttings but only less than 10% of the adult had rooted. At 47 days much more adult cuttings had roots and now the juvenile were almost all rooted (Fig. 3) Shoot formation occurred much later. Almost three months after cutting about 70% of the juvenile and 30% of the adult cuttings had formed visible shoots. At four months almost 90% of all juveniles had shoots compared to only 60% of the adults (Fig. 4) There was no significant effect of wounding the cuttings. Hydroculture of the cuttings during rooting was possible and produced viable propagules just as fast as the sand cultured cuttings. Anatomical examinations of the cuttings during rooting revealed no structural impediments to root formation and emergence that could explain the differences between juvenile and adult cuttings. The details of these investigations will be published elsewhere. DISCUSSION Propagation of S. stuckyi was possible. The differences between adult and juvenile cuttings could not be ameliorated by auxin treatments which on the contrary caused lower survival rates and had no significant effect on rooting or shoot formation. This is similar to observations on a related species Agave parrasana by Santacruz Revulcaba et al. (1999) Wounding of cuttings did not improve rooting of S. stuckyi as has been found for other species with heavy fiber development of tissues surrounding the site of root initiation (Hartmann et al. 1997) As shown by anatomical examinations the roots formed in the leaf cuttings of S. stuckyi grew down through the leaf tissues, thus the fibers did not present a real barrier to root growth and emergence. The further growth of propagules proceeded at a slow rate for all treatments, but after almost a year the plants from juvenile leaves had significantly more, but not longer shoots. For a plant to be marketable meter long shoots or leaves are required. Thus the production time becomes much too long for profitable growing of these plants in greenhouses. However outdoor production in tropical or subtropical areas is feasible. Literature Cited Brown, N.E. (1915) Sansevieria. A monograph of all the known species. Bulletin of Miscellaneous Information XXI Kew Gardens. Chahinian, (2001) In praise of Sansevieria. J. Int. Sansevieria Soc. 1:1 5. Davies, F.T. Lazarte, J.E. and Joiner, J.N. (1982) Initiation and development of roots in juvenile and mature leaf bud cuttings of Ficus pumila L. Amer. J. Bot. 69: 804 812. Eggeli, U. (1994) Sukkulenten. Ulmer,Stuttgart. Hackett, W.P. (1988) The influence of auxin, catechol, and methanolic tissue extracts on", "author_names": [ "M Aarseth-Hansen", "Jette Dahl Moller", "Jorgen Damgaard", "Arne Skytt Andersen" ], "corpus_id": 91098287, "doc_id": "91098287", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "SANSEVIERIA STUCKYI POTENTIAL AS POTTED PLANT", "venue": "", "year": 2005 }, { "abstract": "The ability of a commercial starter culture to perform a sausage fermentation was evaluated by culture dependent and independent methods. The starter culture, as well as the sausage during fermentation, was sampled and strains of lactic acid bacteria (LAB) and coagulase negative cocci (CNC) were isolated. After identification it was determined that Lactobacillus plantarum, contained in the inoculated starter, was the main LAB representative that conducted the transformation, while Staphylococcus xylosus, not declared in the label of the starter culture, was able to colonize the sausages studied. Molecular characterization of isolated Lb. plantarum and S. xylosus highlighted that the commercial mix contained several strains of the same species, and their behavior during the fermentation was different. Analysis of the nucleic acids extracted directly from the sausages confirmed the performance of Lb. plantarum, which was present and active throughout the fermentation, and highlighted the contribution of Lactobacillus curvatus. Introduction For fermented sausage production, the starter cultures are represented by mixtures of lactic acid bacteria (LAB) and coagulase negative cocci (CNC) LAB are the main population responsible for the pH drop, followed by a second step in which CNC are neutralizing the organic acids produced by LAB, through production of peptides and aminoacids from their proteolytic activity. In addition, CNC are able to induce the release of various aromatic substances due to their capability to produce lipases (Montel et al. 1996) Recently, direct amplification of DNA and RNA by polymerase chain reaction (PCR) followed by denaturing gradient gel electrophoresis (DGGE) (Muyzer et al. 1993) showed very good applicability in monitoring the microbial ecology of Italian fermented sausages (Cocolin et al. 2001; Rantsiou et al. 2005) In this paper we wanted to validate the use of a commercial starter for the production of fermented sausages by molecular methods. DGGE was used to analyze PCR and RT PCR products obtained from DNA and RNA extracted directly from the sample to monitor the bacterial dynamics during transformation. Moreover, LAB and CNC were isolated both from the starter culture and during fermentation and subsequently subjected to RAPD analysis to understand if the strains inoculated were able to conduct the fermentation process considered in the study. Materials and Methods Fermented sausages were prepared in a local meat factory using traditional techniques as previously described (Comi et al. 2005) and inoculated with 20 g starter culture containing S. carnosus and Lb. plantarum (Biostart SL1 200, Wiesby GMBH Co. Niebull, Germany) The ripening was conducted for 28 days. The fermented sausages were analyzed in triplicates at 0, 3, 5, 7, 14 and 28 days. Potentiometric measurements of pH were made using a pin electrode of a pH meter (Radiometer Copenhagen pH M82, Cecchinato, Italy) The starter culture (20 g) of the same batch that was used in the production followed, was resuspended in 200 ml sterile water and left at room temperature for 30 min and serial dilutions were prepared in saline/peptone water (8 g/l NaCl, 1 g/l bacteriological peptone, Oxoid, Milan, Italy) and analyzed on MRS agar (Oxoid) incubated with a double layer at 30degC for 48 h and on Mannitol Salt Agar (MSA, Oxoid) incubated at 30degC for 48 h. Fifteen colonies of LAB were isolated from MRS agar and the same number of CNC were selected from MSA agar. The fermented sausages were analyzed to monitor the dynamic changes in the populations responsible for the ripening of fermented sausages, as well as their hygienic quality. In particular, 25 g of each sample were transferred into a sterile stomacher bag and 225 ml of saline/peptone water were added and mixed for 1 min and 30 s in a Stomacher machine (PBI, Italy) Further decimal dilutions were made and the following analyses were carried out on duplicate agar plates: a) total bacterial count (TBC) on Gelisate Agar (Oxoid) incubated for 48 72 h at 30degC; b) LAB on MRS agar; c) CNC on MSA (Oxoid)", "author_names": [ "Luca Simone Cocolin", "Rosalinda Urso", "Kalliopi Rantsiou", "Carlo Cantoni", "Giuseppe Comi" ], "corpus_id": 98512162, "doc_id": "98512162", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Monitoring of a starter culture for fermented sausages by molecular methods", "venue": "", "year": 2005 }, { "abstract": "PubMed Jia G et al; Environ Sci Technol 39 (5) 1378 83 (2005) from HSDB /ALTERNATIVE and IN VITRO TESTS/ Using light microscopy and spectrophotometry, it has been shown that water soluble fullerene C60 cause lysis of human and rat erythrocytes. Fullerene C60 partly inhibited the activities of membrane associated phosphofructokinase and cytoplasmic lactate dehydrogenase in erythrocytes. /Water soluble fullerene C60/ Solomadin IN et al; Biology Bulletin 35 (4) 436 40 (2008) from HSDB /IMMUNOTOXICITY/ .In this study, /investigators/ studied the immunotoxic mechanism and change of gene expression caused by the instillation of C60s. As a result, C60s induced an increase in sub G1 and G1 arrest in BAL cells, an increase in pro inflammatory cytokines such as IL 1, TNF alpha, and IL 6, and an increase of Th1 cytokines such as IL 12 and IFN r in BAL fluid. In addition, IgE reached the maximum at 1 day after treatment in both BAL fluid and the blood, and decreased in a time dependent manner. Gene expression of the MHC class II (H2 Eb1) molecule was stronger than that of the MHC class I (H2 T23) and an increase in T cell distribution was also observed during the experiment period. Furthermore, cell infiltration and expression of tissue damage related genes in lung tissue were constantly observed during the experiment period. Based on this, C60s may induce inflammatory responses in the lung of mice. Abstract: PubMed Park EJ et al; Toxicol Appl Pharmacol 244 (2) 226 33 (2010) from HSDB /IMMUNOTOXICITY/ Hydroxylated fullerenes act as potent inhibitors of cytochrome P450 dependent monooxygenases, and are reported to be very strong antioxidants quenching reactive oxygen species (ROS) production. Effects of nanosized hydroxylated fullerenes on fish neutrophil function and immune gene transcription was investigated using fathead minnow (Pimephales promelas) Neutrophil function assays were used to determine the effects of fullerene exposure in vitro and in vivo on oxidative burst, degranulation and extracellular trap (NETs) release, and the innate immune gene transcription was determined with quantitative PCR (qPCR) Application of fullerenes (0.2 200 ug/mL( 1)in vitro) caused concentration dependent inhibition of oxidative burst and suppressed the release of NETs and degranulation of primary granules (up to 70, 40, and 50% reduction in activity compared to non treated control, respectively) Transcription of interleukin 11 and myeloperoxidase genes was significantly increased and transcription of elastase 2 gene was significantly decreased in fish exposed to hydroxylated fullerenes for 48 hr in vivo (12 and 3 fold increase, and 5 fold decrease, respectively) Observed changes in gene transcription and neutrophil function indicate potential for hydroxylated fullerenes to interfere with the evolutionary conserved innate immune system responses and encourages the use of fish models in studies of nanoparticle immunotoxicity. /Hydroxylated fullerenes/ Abstract: PubMed Jovanovic B et al; Aquat Toxicol 101 (2) 474 82 (2011) from HSDB /IMMUNOTOXICITY/ In the present study, mice received fullerenes intratracheally and were sacrificed at days 1, 6 and 42. Mice that received fullerenes exhibited increased proliferation of splenocytes and increased splenic production of IL 2 and TNF alpha. Changes in the spleen in response to fullerene treatment occurred at different time points than in the lung tissue. Furthermore, fullerenes induced CDK2 expression and activated NF alphaB and NFAT in splenocytes at 6 days post administration. Finally, CD11b( cells were demonstrated to function as responder cells to fullerene administration in the splenic inflammatory process. Taken together, in addition to the effects on pulmonary responses, fullerenes also modulate the immune system. Abstract: PubMed Ding N et al; J Hazard Mater 194: 324 30 (2011) from HSDB /OTHER TOXICITY INFORMATION/ The use of C(60) fullerenes is expected to increase in various industrial fields. Little is known about the potential toxicological mechanism of action of water soluble C(60) fullerenes. In our previous research, gene expression profiling of the rat lung was performed after whole body inhalation exposure to C(60) fullerenes to gain insights into the molecular events. These DNA microarray based data closely matched the pathological findings that C(60)fullerenes caused no serious adverse pulmonary effects under the inhalation exposure condition. Taking advantage of this, we attempted to characterize timedependent changes in the gene expression profiles after intratracheal instillation with C(60) fullerenes at different dosages and to identify the candidate expressed genes as potential biomarkers. The hierarchical cluster analysis revealed that the upor downregulation of genes after intratracheal instillation with 1.0 mg C(60) fullerene particles in rat lung tissue was significantly over represented in the \"response to stimulus\" and \"response to chemical stimulus\" categories of biological processes and in the \"extracellular space\" category of the cellular component. These results were remarkable for 1 week after the instillation with C(60) fullerenes. In the lung tissues instilled with 1.0 mg C(60) fullerene particles, many representative genes involved in \"inflammatory response,\" such as the Cxcl2, Cxcl6, Orm1, and Spp1 genes, and in \"matrix metalloproteinase activity,\" such as the Mmp7 and Mmp12 genes, were upregulated for over 6 months. The expression levels of 89 and 21 genes were positively correlated with the C(60) fullerene dose at 1 week and 6 months after the instillation, respectively. Most of them were involved in \"inflammatory response\" and the Ccl17, Ctsk, Cxcl2, Cxcl6, Lcn6, Orm1, Rnase9, Slc26a4, Spp1, Mmp7, and Mmp12 genes were overlapped. Meanwhile, the expression levels of 16 and 4 genes were negatively correlated with the C(60) fullerene dose at 1 week and 6 months after the instillation, respectively. Microarray based gene expression profiling suggested that the expression of some genes is correlated with the dose of intratracheally instilled C(60)fullerenes. We propose that these genes are useful for identifying potential biomarkers in acute phase or persistent responses to C(60) that these genes are useful for identifying potential biomarkers in acute phase or persistent responses to C(60) fullerenes in the lung tissue. Abstract: PubMed Fujita K et al; Toxicology 274 (1 3) 34 41 (2010) from HSDB /OTHER TOXICITY INFORMATION/ Buckminsterfullerene (C60) can form water suspensions (nC60) that exert toxic effects. While reactive oxygen species (ROS) generation has been implicated as the mechanism for mammalian cytotoxicity, /it is proposed/ that nC60 exerts ROS independent oxidative stress in bacteria, with evidence of protein oxidation, changes in cell membrane potential, and interruption of cellular respiration. This mechanism requires direct contact between the nanoparticle and the bacterial cell and differs from previously reported nanomaterial antibacterial mechanisms that involve ROS generation (metal oxides) or leaching of toxic elements (nanosilver) Abstract: PubMed Lyon D, Alvarez P; Environ Sci Technol 42 (21) 8127 32 (2008)", "author_names": [], "corpus_id": 210846425, "doc_id": "210846425", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Fullerene C60 C60 PubChem", "venue": "", "year": 2019 } ]

[ { "abstract": "Metal halide perovskite materials are an emerging class of solution processable semiconductors with considerable potential for use in optoelectronic devices1 3. For example, light emitting diodes (LEDs) based on these materials could see application in flat panel displays and solid state lighting, owing to their potential to be made at low cost via facile solution processing, and could provide tunable colours and narrow emission line widths at high photoluminescence quantum yields4 8. However, the highest reported external quantum efficiencies of green and red light emitting perovskite LEDs are around 14 per cent7,9 and 12 per cent8, respectively still well behind the performance of organic LEDs10 12 and inorganic quantum dot LEDs13. Here we describe visible light emitting perovskite LEDs that surpass the quantum efficiency milestone of 20 per cent. This achievement stems from a new strategy for managing the compositional distribution in the device an approach that simultaneously provides high luminescence and balanced charge injection. Specifically, we mixed a presynthesized CsPbBr3 perovskite with a MABr additive (where MA is CH3NH3) the differing solubilities of which yield sequential crystallization into a CsPbBr3/MABr quasi core/shell structure. The MABr shell passivates the nonradiative defects that would otherwise be present in CsPbBr3 crystals, boosting the photoluminescence quantum efficiency, while the MABr capping layer enables balanced charge injection. The resulting 20.3 per cent external quantum efficiency represents a substantial step towards the practical application of perovskite LEDs in lighting and display.A strategy for managing the compositional distribution in metal halide perovskite light emitting diodes enables them to surpass 20% external quantum efficiency a step towards their practical application in lighting and displays.", "author_names": [ "Kebin Lin", "Jun Xing", "Li Na Quan", "F Pelayo Garcia Arquer", "Xiwen Gong", "Jianxun Lu", "Liqiang Xie", "Weijie Zhao", "Di Zhang", "Chuanzhong Yan", "Wenqiang Li", "Xinyi Liu", "Yan Lu", "Jeffrey Kirman", "Edward H Sargent", "Qihua Xiong", "Zhanhua Wei" ], "corpus_id": 52958604, "doc_id": "52958604", "n_citations": 1303, "n_key_citations": 4, "score": 1, "title": "Perovskite light emitting diodes with external quantum efficiency exceeding 20 per cent", "venue": "Nature", "year": 2018 }, { "abstract": "Trihalide perovskite semiconductors are emerging as promising emitting materials in light emitting diodes in view of their low cost manufacture, solution processing, and high color purity [1] However, the highest external quantum efficiency reported for perovskite LEDs has so far resided near 14% The low photoluminescence quantum efficiency of the active layer, and an unbalanced charge injection rate, have until now kept perovskite LEDs performance well below that of the best organic and inorganic LEDs. Here we report visible perovskite LEDs that surpass the 20% quantum efficiency milestone. This stems from a new compositional distribution management strategy that simultaneously provides high luminescence and balanced charge injection. We mix a pre synthesized CsPbBr3 perovskite with MABr (MA CH3NH3) additive in the precursor; the different solubility of which yields sequential crystallization into a CsPbBr3@MABr quasi core shell structure. The MABr shell passivates nonradiative defects otherwise present in CsPbBr3 crystals, boosting their photoluminescence quantum efficiency; and the MABr capping layer enables balanced charge injection. We document as a result perovskite LEDs whose EQE reaches 20.3%", "author_names": [ "Zhanhua Wei" ], "corpus_id": 140052590, "doc_id": "140052590", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "High Performance Perovskite Light Emitting Diodes with External Quantum Efficiency Exceeding 20% Achieved via Compositional Distribution Management", "venue": "", "year": 2018 }, { "abstract": "", "author_names": [ "Zhibin Fang", "Yongliang Shi", "Jin Zhao", "Ji Zhang", "Zhengguo Xiao" ], "corpus_id": 214057717, "doc_id": "214057717", "n_citations": 48, "n_key_citations": 1, "score": 0, "title": "Dual Passivation of Perovskite Defects for Light Emitting Diodes with External Quantum Efficiency Exceeding 20%", "venue": "", "year": 2020 }, { "abstract": "", "author_names": [ "Zhengguo Xiao", "Ross A Kerner", "Nhu L Tran", "Lianfeng Zhao", "Gregory D Scholes", "Barry P Rand" ], "corpus_id": 104319753, "doc_id": "104319753", "n_citations": 36, "n_key_citations": 0, "score": 0, "title": "Engineering Perovskite Nanocrystal Surface Termination for Light Emitting Diodes with External Quantum Efficiency Exceeding 15%", "venue": "", "year": 2019 }, { "abstract": "In recent years, substantial progress has been made in developing perovskite light emitting diodes with near infrared, red and green emissions and over 20% external quantum efficiency. However, the development of perovskite light emitting diodes with blue emission remains a great challenge, which retards further development of full color displays and white light illumination based on perovskite emissive materials. Here, firstly, through composition and dimensional engineering, we prepare quasi two dimensional perovskite thin films with improved blue emission, taking advantages of reduced trap density and enhanced photoluminescence quantum yield. Secondly, we find a vertically non uniform distribution of perovskite crystals in the PEDOT:PSS/perovskite hybrid film. Through modulating the position of the recombination zone, we activate the majority of quasi two dimensional perovskite crystals, and thus demonstrate the most efficient blue perovskite light emitting diode to date with emission peak at 480 nm, record luminance of 3780 cd m 2 and record external quantum efficiency of 5.7%.Halide perovskite based light emitting diodes attracted intensive research interest recently but the efficiency of blue diodes is much lower than the green and red ones. Here Li et al. push up the efficiency of blue diodes through composition engineering and vertical morphology control.", "author_names": [ "Zhenchao Li", "Ziming Chen", "Yongchao Yang", "Qifan Xue", "Hin-Lap Yip", "Yong Cao" ], "corpus_id": 70350169, "doc_id": "70350169", "n_citations": 187, "n_key_citations": 1, "score": 0, "title": "Modulation of recombination zone position for quasi two dimensional blue perovskite light emitting diodes with efficiency exceeding 5%", "venue": "Nature Communications", "year": 2019 }, { "abstract": "The absence of highly efficient and stable blue phosphors is still a bottleneck for the development of high quality monochrome and white phosphorescent organic light emitting diodes (OLEDs) Here, we propose a chlorine functionalization strategy for blue phosphors, and a series of aromatic chlorine based high efficiency blue iridium(III) phosphors (Ir1 Ir4) containing various ancillary ligands was designed and prepared. These phosphors show intensive blue emissions withPL peaks of 468 476 nm and a high PhPL of 0.70 0.85 in dichloromethane. Using these blue phosphors as emitters, the fabricated OLEDs also realize similar blue emissions with the peaks located at 472, 484, 476, and 476 nm for the Ir1 Ir4 based OLEDs, respectively. Moreover, the Ir2 and Ir3 based OLEDs exhibit extremely high EQEs exceeding the theoretical limit, reaching 20.43% and 21.41% respectively. In addition, the two color white OLED with Ir3 as the blue emitter also achieves an extremely high device efficiency, having a maximum EQE of up to 20.17% The excellent blue emission and high device efficiency indicates that the four phosphors have huge potential applications for high performance blue and white phosphorescent OLEDs.", "author_names": [ "Yanqin Miao", "Peng Tao", "Long Gao", "Xiangling Li", "Liuwei Wei", "Shujuan Liu", "Hua Wang", "Bingshe Xu", "Qiang Zhao" ], "corpus_id": 139571640, "doc_id": "139571640", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Highly efficient chlorine functionalized blue iridium(III) phosphors for blue and white phosphorescent organic light emitting diodes with the external quantum efficiency exceeding 20%", "venue": "", "year": 2018 }, { "abstract": "Triarylboron compounds have attracted much attention, and found wide use as functional materials because of their electron accepting properties arising from the vacant p orbitals on the boron atoms. In this study, we design and synthesize new donor acceptor triarylboron emitters that show thermally activated delayed fluorescence. These emitters display sky blue to green emission and high photoluminescence quantum yields of 87 100 in host matrices. Organic light emitting diodes using these emitting molecules as dopants exhibit high external quantum efficiencies of 14.0 22.8 which originate from efficient up conversion from triplet to singlet states and subsequent efficient radiative decay from singlet to ground states.", "author_names": [ "Katsuaki Suzuki", "Shosei Kubo", "Katsuyuki Shizu", "Tatsuya Fukushima", "Atsushi Wakamiya", "Yasujiro Murata", "Chihaya Adachi", "Hironori Kaji" ], "corpus_id": 45114149, "doc_id": "45114149", "n_citations": 195, "n_key_citations": 1, "score": 0, "title": "Triarylboron Based Fluorescent Organic Light Emitting Diodes with External Quantum Efficiencies Exceeding 20", "venue": "Angewandte Chemie", "year": 2015 }, { "abstract": "Metal halide perovskites have received considerable attention in the field of electroluminescence, and the external quantum efficiency of perovskite light emitting diodes has exceeded 20% CH 3 NH 3 PbBr 3 has been intensely investigated as an emitting layer in perovskite light emitting diodes. However, perovskite films comprising CH 3 NH 3 PbBr 3 often exhibit low surface coverage and poor crystallinity, leading to high current leakage, severe nonradiative recombination, and limited device performance. Herein, we demonstrate a rationale for composition engineering to obtain high quality perovskite films. We first reduce pinholes by adding excess CH 3 NH 3 Br to the actual CH 3 NH 3 PbBr 3 films, and we then add CsBr to improve the crystalline quality and to passivate nonradiative defects. As a result, the (CH 3 NH 3 1 x Cs x PbBr 3 based perovskite light emitting diodes exhibit significantly improved external quantum and power efficiencies of 6.97% and 25.18 lm/W, respectively, representing an improvement in performance dozens of times greater than that of pristine CH 3 NH 3 PbBr 3 based perovskite light emitting diodes. Our study demonstrates that composition engineering is an effective strategy for enhancing the device performance of perovskite light emitting diodes.", "author_names": [ "Chuanzhong Yan", "Kebin Lin", "Jianxun Lu", "Zhanhua Wei" ], "corpus_id": 225503324, "doc_id": "225503324", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Composition engineering to obtain efficient hybrid perovskite light emitting diodes", "venue": "", "year": 2020 }, { "abstract": "Metal halide perovskites are promising candidates for use in light emitting diodes (LEDs) due to their potential for color tunable and high luminescence efficiency. While recent advances in perovskite based light emitting diodes have resulted in external quantum efficiencies exceeding 12.4% for the green emitters, and infrared emitters based on 3 D/2D mixed dimensional perovskites have exceeded 20% the external quantum efficiencies of the red and blue emitters still lag behind. A critical issue to date is creating highly emissive and stable perovskite emitters with the desirable emission band gap to achieve full color displays and white LEDs. Herein, we report the preparation and characterization of a highly luminescent and stable suspension of cubic shaped methylammonium lead triiodide (CH3NH3PbI3) perovskite nanocrystals, where we synthesize the nanocrystals via a ligand assisted reprecipitation technique, using an acetonitrile/methylamine compound solvent system to solvate the ions and toluene as the antisolvent to induce crystallization. Through tuning the ratio of the ligands, the ligand to toluene ratio, and the temperature of the toluene, we obtain a solution of CH3NH3PbI3 nanocrystals with a photoluminescence quantum yield exceeding 93% and tunable emission between 660 and 705 nm. We also achieved red emission at 635 nm by blending the nanocrystals with bromide salt and obtained perovskite based light emitting diodes with maximum electroluminescent external quantum efficiency of 2.75%", "author_names": [ "Yasser Hassan", "Olivia J Ashton", "Jong Hyun Park", "Guangru Li", "Nobuya Sakai", "Bernard Wenger", "Amir A Haghighirad", "Nakita K Noel", "Myoung Hoon Song", "Bo Ram Lee", "Richard H Friend", "Henry J Snaith" ], "corpus_id": 58570337, "doc_id": "58570337", "n_citations": 54, "n_key_citations": 0, "score": 0, "title": "Facile Synthesis of Stable and Highly Luminescent Methylammonium Lead Halide Nanocrystals for Efficient Light Emitting Devices.", "venue": "Journal of the American Chemical Society", "year": 2019 }, { "abstract": "Perovskite light emitting diodes (PeLEDs) have showed significant progress in recent years; the external quantum efficiency (EQE) of electroluminescence in green and red regions has exceeded 20% but the efficiency in blue lags far behind. Here, a large cation CH3CH2NH2+ is added in PEA2(CsPbBr3)2PbBr4 perovskite to decrease the Pb Br orbit coupling and increase the bandgap for blue emission. X ray diffraction and nuclear magnetic resonance results confirmed that the EA has successfully replaced Cs+ cations to form PEA2(Cs1 xEAxPbBr3)2PbBr4. This method modulates the photoluminescence from the green region (508 nm) into blue (466 nm) and over 70% photoluminescence quantum yield in blue is obtained. In addition, the emission spectra is stable under light and thermal stress. With configuration of PeLEDs with 60% EABr, as high as 12.1% EQE of sky blue electroluminescence located at 488 nm has been demonstrated, which will pave the way for the full color display for the PeLEDs. Blue light emitting diodes (LEDs) are critical for displays. Employing a large organic cation into a quasi two dimensional perovskite with green emission, Chu et al. achieve LEDs exhibiting a high external quantum efficiency of 12.1% and stable spectra in the sky blue region.", "author_names": [ "Zema Chu", "Yang Zhao", "Fei Ma", "Cai-Xin Zhang", "Huixiong Deng", "Fengli Gao", "Qiufeng Ye", "Junhua Meng", "Zhigang Yin", "Xingwang Zhang", "Jingbi You" ], "corpus_id": 221182547, "doc_id": "221182547", "n_citations": 39, "n_key_citations": 2, "score": 0, "title": "Large cation ethylammonium incorporated perovskite for efficient and spectra stable blue light emitting diodes", "venue": "Nature Communications", "year": 2020 } ]

[ { "abstract": "Abstract Researchers are using different types of nanomaterials for the enhancement of the thermal performance of regular fluids such as water, kerosene oil, etc. However, these days, the researchers are more interested in hybrid nanomaterials. The purpose of this communication is to examine the stability analysis of Cu Al2O3/water hybrid nanofluid over a non linear shrinking sheet. The hybrid nanomaterials are composed of Cu and Al2O3. These hybridized nanomaterials are then dissolved in water taken as base fluid to form Cu Al2O3//water hybrid nanofluid. Mathematical analysis and modeling have been attended in the presence of viscous dissipation and suction/injection effects. The governing equations of mathematical models are transformed into self similar solutions in the form of ODEs by using similarity transformation. Solutions of the non linear ODEs are created by employing of three stage Lobatto IIIa formula which is built in BVP4C function in the MATLAB software. A comparison of the current study has been done with the preceding published literature. The distributions of velocity, temperature profiles, coefficient of skin friction and heat transfer rate are presented graphically and conferred for numerous significant parameters entering into the problem. Results revealed the existence of dual solutions for a certain range of the suction/blowing parameter. Stability analysis is also done in order to obtain dual solutions stability. The smallest eigenvalues suggest that the first solution is stable from the second solution. Hybrid nanomaterials have a high scope toward nurturing our day to day life.", "author_names": [ "Liaquat Ali Lund", "Zurni Omar", "Ilyas Khan", "Asiful H Seikh", "El-Sayed M Sherif", "Kottakkaran Sooppy Nisar" ], "corpus_id": 211027386, "doc_id": "211027386", "n_citations": 51, "n_key_citations": 0, "score": 1, "title": "Stability analysis and multiple solution of Cu Al2O3/H2O nanofluid contains hybrid nanomaterials over a shrinking surface in the presence of viscous dissipation", "venue": "", "year": 2020 }, { "abstract": "Significant variations in Raman shifts with decreasing material size, D, have been detected in Raman spectroscopy. In this study, we propose a simple and unified model to determine and explain the size dependent Raman shift, o(D) of low dimensional semiconductor nanomaterials. o(D) was found to be a function of bond number in a system, with an obvious decline in Raman shift observed when size dropped to the nanoscale. This arose from a decrease in coordination number, Z(D) and increase in single bond strength, e(D) The predicted results show good agreement with experimental data for a series of semiconductor nanomaterials, showing that bond number can be used to calculate Raman shifts of nanomaterials. Moreover, this theoretical model was successfully applied to both single crystals and some binary semiconductor nanomaterials. Furthermore, bond number, which is directly related to the nanomaterial shape and size, becomes the only parameter required to determine o(D) in this model, as both Z(D) and e(D) can be determined from the bond number. This indicates that the established model has the potential to determine Raman shifts of nanomaterials with different shapes and sizes.", "author_names": [ "Huawei Li", "X W He", "Han Xiao", "H N Du", "Jinlan Wang", "Hong Zhang" ], "corpus_id": 46844798, "doc_id": "46844798", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Size dependent Raman shift of semiconductor nanomaterials determined using bond number and strength.", "venue": "Physical chemistry chemical physics PCCP", "year": 2017 }, { "abstract": "ABSTRACT The size and shape dependent band gap energy of semiconductor compound nanomaterials (SCNs) is formulated. The model theory is based on the cohesive energy of the nanocrystals compared to the bulk crystals. We have considered CdSe, CdTe, ZnS, ZnSe and ZnTe semiconductors compounds for the study of size and shape dependent band gap energy. It is found that the band gap energy of SCN depends upon the particle size and shape. The model predicts that the band gap energy increases as particle size of the semiconductor nanomaterials decreases. The results obtained are compared with the available experimental data, which support the validity of the model reported.", "author_names": [ "Madan Singh", "Monika Goyal", "Kamal Devlal" ], "corpus_id": 218526219, "doc_id": "218526219", "n_citations": 77, "n_key_citations": 0, "score": 0, "title": "Size and shape effects on the band gap of semiconductor compound nanomaterials", "venue": "", "year": 2018 }, { "abstract": "Band gap energy narrowing upon doping is consider as a general phenomenon in semiconductors. However, low surface area still the main problem that limits its wide applications. Herein, incorporation of ZnO on the surface and inside the matrix of SiO2 using CTAB as structural and capping agent have prepared via sol gel wet chemical pathway. The crystalline size, structural and textural properties of the obtained samples were investigated through different techniques like XRD, SBET surface area, UV Vis spectroscopy, FESEM and TEM. The results indicate that the surface area and pore volume constant decrease by insertion of ZnO nanoparticles in the pore wall and/or above the surface of silica. In the other hand, the organic materials removal enhanced due to the existence of different types of pores ranging from microspores to wide mesoporous system. Following the nanomaterials preparation and characterizations, some experiments have done to check the effect on the organic materials like dyes removal. One of these tests is COD result, which affirm the good degradation for most of MB dye that exist in the solution. Furthermore, the scavenger study results show that the ZnO@SiO2 nanomaterials displayed good photocatalytic properties compared to the bare silica one via its charge carrier and reactive hydroxyl radicals species. The scrutinization at the features of the obtained materials enable us to offering without doubt a promising photocatalyst candidate for different applications in wastewater and water treatment.", "author_names": [ "M F Abdel Messih", "Ahmed Esmail Shalan", "Mohamed Fathi Sanad" ], "corpus_id": 199185622, "doc_id": "199185622", "n_citations": 25, "n_key_citations": 0, "score": 0, "title": "Facile approach to prepare ZnO@SiO2 nanomaterials for photocatalytic degradation of some organic pollutant models", "venue": "Journal of Materials Science: Materials in Electronics", "year": 2019 }, { "abstract": "The distribution of constant electric current potential in case of probe measurement on anisotropic semiconductors and fields has been studied. The expressions for potential distribution have been obtained. It enables to identify the area of the probe field of the scanning microscope in case an anisotropic film is under study. The results of the research demonstrate the correlation between the size and anisotropy of specific electroconductivity and the resistance change of probe spreading in limited films.", "author_names": [ "Vladimir Filippov", "Sergey Mitsuk", "Sergey Luzyanin" ], "corpus_id": 209853444, "doc_id": "209853444", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Electric Field Mathematical Modelling at Probe Measurement in Anisotropic Semiconductor Films", "venue": "2019 1st International Conference on Control Systems, Mathematical Modelling, Automation and Energy Efficiency (SUMMA)", "year": 2019 }, { "abstract": "The size and shape dependent band gap energy of semiconductor compound nanomaterials (SCNs) is formulated. The model theory is based on the cohesive energy of the nanocrystals compared to the bulk.", "author_names": [ "Madan Singh", "Monika Goyal", "Kamal Devlal" ], "corpus_id": 136316318, "doc_id": "136316318", "n_citations": 51, "n_key_citations": 0, "score": 0, "title": "Size and shape effects on the band gap of semiconductor compound nanomaterials", "venue": "", "year": 2017 }, { "abstract": "This paper describes the development and verification of mathematical models which will approximate the electrical characteristics of Zener and/or avalanche diodes and tunnel diodes. Each model consists of a circuit of discrete components with their defining equations. The equations are in a form compatible with the digital computer language which makes the models useful in analysis and design, by computer, of electronic circuits containing these devices. The Zener diode model is basically the familiar Ebers Moll conventional diode model except that additional current sources have been added to approximate the voltage regulation when breakdown of the junction occurs. The equation for junction capacitance has been modified to model the decrease in capacitance due to avalanche in the junction. A tunnel diode model is presented which approximates the entire static characteristic, including the negative resistance region. Methods for extracting model parameters from a limited number of easily obtainable data points are developed. A method for measuring and describing junction capacitance is also presented.", "author_names": [ "Marvin E Daniel" ], "corpus_id": 62704744, "doc_id": "62704744", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Development of mathematical models of semiconductor devices for computer aided circuit analysis", "venue": "", "year": 1967 }, { "abstract": "In designing and optimizing new generation nanomaterials and related quantum devices, dissipation versus decoherence phenomena are often accounted for via local scattering models, such as relaxation time and Boltzmann like schemes. Here we show that the use of such local scattering approaches within the Wigner function formalism may lead to unphysical results, namely anomalous suppression of intersubband relaxation, incorrect thermalization dynamics, and violation of probability density positivity. Furthermore, we propose a quantum mechanical generalization of relaxation time and Boltzmann like models, resulting in nonlocal scattering superoperators that enable one to overcome such limitations.", "author_names": [ "Rita Claudia Iotti", "Fabrizio Dolcini", "Fausto Rossi" ], "corpus_id": 59362146, "doc_id": "59362146", "n_citations": 15, "n_key_citations": 1, "score": 0, "title": "Wigner function formalism applied to semiconductor quantum devices: Need for nonlocal scattering models", "venue": "", "year": 2017 }, { "abstract": "Optically bright colloidal semiconductor nanocrystals (CSNCs) are important nanomaterials because of their potential applications such as cellular imaging and solid state lighting. The optoelectronic properties of CSNCs are strongly controlled by the chemical nature of the surface passivating ligands that are introduced during their synthesis. However, the existing LaMer growth model does not provide a clear understanding of the stage when ligands become attached onto the CSNC surface. Herein, apart from the three stage formation mechanism of CSNCs (supersaturation, nucleation, and growth) an entirely new stage solely involving surface ligand attachment onto fully grown CSNCs is now reported that controls their photoluminescence properties. Furthermore, we also demonstrate a fundamentally new surface modification approach using partially passivated CSNCs to introduce a variety of functional groups (azide, alkene, and siloxane) including photoisomerizable molecular machines (e.g. azobenzene) without th.", "author_names": [ "Meghan B Teunis", "Thakshila Liyanage", "Sukanta Dolai", "Barry B Muhoberac", "Rajesh Sardar", "Mangilal Agarwal" ], "corpus_id": 55067093, "doc_id": "55067093", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Unraveling the Mechanism Underlying Surface Ligand Passivation of Colloidal Semiconductor Nanocrystals: A Route for Preparing Advanced Hybrid Nanomaterials", "venue": "", "year": 2017 }, { "abstract": "One thing in common: The formation of binary colloidal semiconductor nanocrystals from single (M(EEPPh2 )n and dual source precursors (metal carboxylates M(OOCR)n and phosphine chalcogenides such as E=PHPh2 is found to proceed through a common mechanism. For CdSe as a model system (31) P NMR spectroscopy and DFT calculations support a reaction mechanism which includes numerous metathesis equilibriums and Se exchange reactions.", "author_names": [ "Kui Yu", "Xiang-Yang Liu", "Qun Zeng", "Mingli Yang", "Jianying Ouyang", "Xinqin Wang", "Ye Tao" ], "corpus_id": 29320370, "doc_id": "29320370", "n_citations": 27, "n_key_citations": 1, "score": 0, "title": "The formation mechanism of binary semiconductor nanomaterials: shared by single source and dual source precursor approaches.", "venue": "Angewandte Chemie", "year": 2013 } ]

[ { "abstract": "Advanced oxidation processes via semiconductor photocatalysis for water treatment have been the subject of extensive research over the past three decades, producing many scientific reports focused on elucidating mechanisms and enhancing kinetics for the treatment of contaminants in water. Many of these reports imply that the ultimate goal of the research is to apply photocatalysis in municipal water treatment operations. However, this ignores immense technology transfer problems, perpetuating a widening gap between academic advocation and industrial application. In this Feature, we undertake a critical examination of the trajectory of photocatalytic water treatment research, assessing the viability of proposed applications and identifying those with the most promising future. Several strategies are proposed for scientists and engineers who aim to support research efforts to bring industrially relevant photocatalytic water treatment processes to fruition. Although the reassessed potential may not live up to initial academic hype, an unfavorable assessment in some areas does not preclude the transfer of photocatalysis for water treatment to other niche applications as the technology retains substantive and unique benefits.", "author_names": [ "Stephanie K Loeb", "Pedro J J Alvarez", "Jonathon Brame", "Ezra L Cates", "Wonyong Choi", "John C Crittenden", "Dionysios D Dionysiou", "Qilin Li", "Gianluca Li-Puma", "Xie Quan", "David L Sedlak", "T David Waite", "Paul K Westerhoff", "Jae-Hong Kim" ], "corpus_id": 58569309, "doc_id": "58569309", "n_citations": 179, "n_key_citations": 2, "score": 0, "title": "The Technology Horizon for Photocatalytic Water Treatment: Sunrise or Sunset?", "venue": "Environmental science technology", "year": 2019 }, { "abstract": "In recent years, semiconductor photocatalytic process has shown a great potential as a low cost, environmental friendly and sustainable treatment technology to align with the \"zero\" waste scheme in the water/wastewater industry. The ability of this advanced oxidation technology has been widely demonstrated to remove persistent organic compounds and microorganisms in water. At present, the main technical barriers that impede its commercialisation remained on the post recovery of the catalyst particles after water treatment. This paper reviews the recent R&D progresses of engineered photocatalysts, photoreactor systems, and the process optimizations and modellings of the photooxidation processes for water treatment. A number of potential and commercial photocatalytic reactor configurations are discussed, in particular the photocatalytic membrane reactors. The effects of key photoreactor operation parameters and water quality on the photo process performances in terms of the mineralization and disinfection are assessed. For the first time, we describe how to utilize a multi variables optimization approach to determine the optimum operation parameters so as to enhance process performance and photooxidation efficiency. Both photomineralization and photo disinfection kinetics and their modellings associated with the photocatalytic water treatment process are detailed. A brief discussion on the life cycle assessment for retrofitting the photocatalytic technology as an alternative waste treatment process is presented. This paper will deliver a scientific and technical overview and useful information to scientists and engineers who work in this field.", "author_names": [ "Meng Nan Chong", "Bo Jin", "Christopher W K Chow", "Christopher P Saint" ], "corpus_id": 11490118, "doc_id": "11490118", "n_citations": 3562, "n_key_citations": 105, "score": 1, "title": "Recent developments in photocatalytic water treatment technology: a review.", "venue": "Water research", "year": 2010 }, { "abstract": "Natural organic matter (NOM) is a complex matrix of organic substances produced in (or channeled to) aquatic ecosystems via various biological, geological and hydrological cycles. Such variability is posing a serious challenge to most water treatment technologies, especially the ones designed to treat drinking water supplies. Lately, in addition to the fluctuating composition of NOM, a substantial increase of its concentration in fresh waters, and also municipal wastewater effluents, has been reported worldwide, which justifies the urgent need to develop highly efficient and versatile water treatment processes. Coagulation is among the most applied processes for water and wastewater treatment. The application of coagulation to remove NOM from drinking water supplies has received a great deal of attention from researchers around the world because it was efficient and helped avoiding the formation of disinfection by products (DBPs) Nonetheless, with the increased fluctuation of NOM in water (concentration and composition) the efficiency of conventional coagulation was substantially reduced, hence the need to develop enhanced coagulation processes by optimizing the operating conditions (mainly the amount coagulants and pH) developing more efficient inorganic or organic coagulants, as well as coupling coagulation with other water treatment technologies. In the present review, recent research studies dealing with the application of coagulation for NOM removal from drinking water supplies are presented and compared. In addition, integration schemes combining coagulation and other water treatment processes are presented, including membrane filtration, oxidation, adsorption and others processes.", "author_names": [ "Mika Sillanpaa", "Mohamed Chaker Ncibi", "Anu Matilainen", "Mikko Vepsalainen" ], "corpus_id": 3662863, "doc_id": "3662863", "n_citations": 286, "n_key_citations": 3, "score": 0, "title": "Removal of natural organic matter in drinking water treatment by coagulation: A comprehensive review.", "venue": "Chemosphere", "year": 2018 }, { "abstract": "The global presence of microplastic (MP) in aquatic ecosystems has been shown by various studies. However, neither MP concentrations nor their sources or sinks are completely known. Waste water treatment plants (WWTPs) are considered as significant point sources discharging MP to the environment. This study investigated MP in the effluents of 12 WWTPs in Lower Saxony, Germany. Samples were purified by a plastic preserving enzymatic oxidative procedure and subsequent density separation using a zinc chloride solution. For analysis, attenuated total reflection Fourier transform infrared spectroscopy (ATR FT IR) and focal plane array (FPA) based transmission micro FT IR imaging were applied. This allowed the identification of polymers of all MP down to a size of 20 mm. In all effluents MP was found with quantities ranging from 0 to 5 x 101 m 3 MP 500 mm and 1 x 101 to 9 x 103 m 3 MP 500 mm. By far, polyethylene was the most frequent polymer type in both size classes. Quantities of synthetic fibres ranged from 9 x 101 to 1 x 103 m 3 and were predominantly made of polyester. Considering the annual effluxes of tested WWTPs, total discharges of 9 x 107 to 4 x 109 MP particles and fibres per WWTP could be expected. Interestingly, one tertiary WWTP had an additionally installed post filtration that reduced the total MP discharge by 97% Furthermore, the sewage sludge of six WWTPs was examined and the existence of MP, predominantly polyethylene, revealed. Our findings suggest that WWTPs could be a sink but also a source of MP and thus can be considered to play an important role for environmental MP pollution.", "author_names": [ "Svenja M Mintenig", "Ivo Int-Veen", "Martin G J Loder", "Sebastian Primpke", "Gunnar Gerdts" ], "corpus_id": 46880864, "doc_id": "46880864", "n_citations": 499, "n_key_citations": 20, "score": 0, "title": "Identification of microplastic in effluents of waste water treatment plants using focal plane array based micro Fourier transform infrared imaging.", "venue": "Water research", "year": 2017 }, { "abstract": "Centralized water treatment has dominated in developed urban areas over the past century, although increasing challenges with this model demand a shift to a more decentralized approach wherein advanced oxidation processes (AOPs) can be appealing treatment options. Efforts to overcome the fundamental obstacles that have thus far limited the practical use of traditional AOPs, such as reducing their chemical and energy input demands, target the utilization of heterogeneous catalysts. Specifically, recent advances in nanotechnology have stimulated extensive research investigating engineered nanomaterial (ENM) applications to AOPs. In this Perspective, we critically evaluate previously studied ENM catalysts and the next generation treatment technologies they seek to enable. Opportunities for improvement exist at the intersection of materials science and treatment process engineering, as future research should aim to enhance catalyst properties while considering the unique roadblocks to practical ENM implementation in water treatment.This Perspective evaluates catalysts based on engineered nanomaterials and the next generation water treatment technologies they seek to enable.", "author_names": [ "Brenna C Hodges", "Ezra L Cates", "Jae-Hong Kim" ], "corpus_id": 51929334, "doc_id": "51929334", "n_citations": 226, "n_key_citations": 1, "score": 0, "title": "Challenges and prospects of advanced oxidation water treatment processes using catalytic nanomaterials", "venue": "Nature Nanotechnology", "year": 2018 }, { "abstract": "As emerging contaminants, antibiotic resistance genes (ARGs) have become a public concern. This study aimed to investigate the occurrence and diversity of ARGs, and variation in the composition of bacterial communities in source water, drinking water treatment plants, and tap water in the Pearl River Delta region, South China. Various ARGs were present in the different types of water. Among the 27 target ARGs, floR and sul1 dominated in source water from three large rivers in the region. Pearson correlation analysis suggested that sul1, sul2, floR, and cmlA could be potential indicators for ARGs in water samples. The total abundance of the detected ARGs in tap water was much lower than that in source water. Sand filtration and sedimentation in drinking water treatment plants could effectively remove ARGs; in contrast, granular activated carbon filtration increased the abundance of ARGs. It was found that Pseudomonas may be involved in the proliferation and dissemination of ARGs in the studied drinking water treatment system. Bacteria and ARGs were still present in tap water after treatment, though they were significantly reduced. More research is needed to optimize the water treatment process for ARG removal.", "author_names": [ "Hao-Chang Su", "You-sheng Liu", "Chang-Gui Pan", "Jun Chen", "Liang-Ying He", "Guang-Guo Ying" ], "corpus_id": 27816179, "doc_id": "27816179", "n_citations": 124, "n_key_citations": 3, "score": 0, "title": "Persistence of antibiotic resistance genes and bacterial community changes in drinking water treatment system: From drinking water source to tap water.", "venue": "The Science of the total environment", "year": 2018 }, { "abstract": "The high concentrations of pharmaceuticals and personal care products (PPCP) that found in water in many locations are of concern. Among the available water treatment methods, heterogeneous photocatalysis using TiO2 is an emerging and viable technology to overcome the occurrence of PPCP in natural and waste water. The combination of carbonaceous materials (e.g. activated carbon, carbon nanotubes and graphene nanosheets) with TiO2, a recent development, gives significantly improved performance. In this article, we present a critical review of the development and fabrication of carbonaceous TiO2 and its application to PPCP removal including its influence on water chemistry, and the relevant operational parameters. Finally, we present an analysis of current priorities in the ongoing research and development of carbonaceous TiO2 for the photodegradation of PPCP.", "author_names": [ "Dion Awfa", "Mohamed Ateia", "Manabu Fujii", "Matthew Stanley Johnson", "Chihiro Yoshimura" ], "corpus_id": 44123626, "doc_id": "44123626", "n_citations": 148, "n_key_citations": 3, "score": 0, "title": "Photodegradation of pharmaceuticals and personal care products in water treatment using carbonaceous TiO2 composites: A critical review of recent literature.", "venue": "Water research", "year": 2018 }, { "abstract": "High silica zeolites have been found to be effective adsorbents for the removal of organic micro pollutants (OMPs) from impaired water, including various pharmaceuticals, personal care products, industrial chemicals, etc. In this review, the properties and fundamentals of high silica zeolites are summarised. Recent research on mechanisms and efficiencies of OMP adsorption by high silica zeolites are reviewed to assess the potential opportunities and challenges for the application of high silica zeolites for OMP adsorption in water treatment. It is concluded that the adsorption capacities are well related to surface hydrophobicity/hydrophilicity and structural features, e.g. micropore volume and pore size of high silica zeolites, as well as the properties of OMPs. By using high silica zeolites, the undesired competitive adsorption of background organic matter (BOM) in natural water could potentially be prevented. In addition, oxidative regeneration could be applied on site to restore the adsorption capacity of zeolites for OMPs and prevent the toxic residues from re entering the environment.", "author_names": [ "Na Jiang", "Ran Shang", "Sebastiaan G J Heijman", "Luuk C Rietveld" ], "corpus_id": 51701342, "doc_id": "51701342", "n_citations": 148, "n_key_citations": 1, "score": 0, "title": "High silica zeolites for adsorption of organic micro pollutants in water treatment: A review.", "venue": "Water research", "year": 2018 }, { "abstract": "Continuous flow photochemistry in microreactors receives a lot of attention from researchers in academia and industry as this technology provides reduced reaction times, higher selectivities, straightforward scalability, and the possibility to safely use hazardous intermediates and gaseous reactants. In this review, an up to date overview is given of photochemical transformations in continuous flow reactors, including applications in organic synthesis, material science, and water treatment. In addition, the advantages of continuous flow photochemistry are pointed out and a thorough comparison with batch processing is presented.", "author_names": [ "Dario Cambie", "Cecilia Bottecchia", "Natan J W Straathof", "Volker Hessel", "Timothy Noel" ], "corpus_id": 206535785, "doc_id": "206535785", "n_citations": 692, "n_key_citations": 2, "score": 0, "title": "Applications of Continuous Flow Photochemistry in Organic Synthesis, Material Science, and Water Treatment.", "venue": "Chemical reviews", "year": 2016 }, { "abstract": "Abstract The utilization of solar energy to drive water treatment processes is a potential sustainable solution to the world's water scarcity issue. In recent years, significant efforts have been devoted to developing and testing innovative solar based water treatment technologies, which are comprehensively reviewed in this paper. Recent developments and applications of seven major solar desalination technologies, solar photocatalysis process and solar disinfection are investigated. Potential integration of solar technologies and desalination processes are summarized. By collecting and analysing performance data from recent studies, the status of productivity, energy consumption and water production costs of different technologies is critically reviewed. The real world applicability as well as technical and economic feasibility is also evaluated. Presently, most of the solar water treatment processes are still under development with limited real applications. Economic competitiveness is among the major reasons that affect the scaling up and commercialization. It is revealed that the reported water costs of small to medium scale solar desalination plants are in the range of US$0.2 22/m3, much higher than conventional fossil fuel based plants. However, the estimated low water costs (US$0.9 2.2/m3) for large scale solar based plants indicate that solar based alternatives will become potentially viable in the near future.", "author_names": [ "Ying Zhang", "Muttucumaru Sivakumar", "Shu-Qing Yang", "Keith Enever", "Mohammad Ramezanianpour" ], "corpus_id": 115575837, "doc_id": "115575837", "n_citations": 114, "n_key_citations": 1, "score": 0, "title": "Application of solar energy in water treatment processes: A review", "venue": "", "year": 2018 } ]

[ { "abstract": "The complex band structures of the bulk materials which constitute the alternating layer (001) semiconductor semiconductor superlattice are investigated. The complex bands near the center of the Brillouin zone in the [001] direction are studied in detail. The decay lengths of superlattice states whose energies lie in the bulk band gaps of one of the semiconductors are determined from the dispersion curves of these bands for imaginary \\stackrel{\\ensuremath{\\rightarrow}\\mathrm{k} This method is applied using a tight binding band structure calculation to two superlattices: the AlAs GaAs superlattice and the CdTe HgTe superlattice. The decay lengths of AlAs GaAs superlattice conduction band minimum states are found to be substantially shorter than those for the CdTe HgTe superlattice. These differences in the decay of the states in the two superlattices result in differences in the variation of the conduction band effective masses with the thickness of the AlAs and CdTe layers. The conduction band effective masses increase more rapidly with AlAs thickness in the AlAs GaAs superlattice than with CdTe thickness in the CdTe HgTe superlattice.", "author_names": [ "J Schulman", "T C Mcgill" ], "corpus_id": 119527552, "doc_id": "119527552", "n_citations": 44, "n_key_citations": 0, "score": 1, "title": "Complex band structure and superlattice electronic states", "venue": "", "year": 1981 }, { "abstract": "Twisted bilayer graphene (TBLG) is one of the simplest van der Waals heterostructures, yet it yields a complex electronic system with intricate interplay between moire physics and interlayer hybridization effects. We report on electronic transport measurements of high mobility small angle TBLG devices showing clear evidence for insulating states at the superlattice band edges, with thermal activation gaps several times larger than theoretically predicted. Moreover, Shubnikov de Haas oscillations and tight binding calculations reveal that the band structure consists of two intersecting Fermi contours whose crossing points are effectively unhybridized. We attribute this to exponentially suppressed interlayer hopping amplitudes for momentum transfers larger than the moire wave vector.", "author_names": [ "Y Cao", "J Y Luo", "Valla Fatemi", "Shiang Fang", "Javier D Sanchez-Yamagishi", "K Watanabe", "Takashi Taniguchi", "Efthimios Kaxiras", "Pablo Jarillo-Herrero" ], "corpus_id": 14039781, "doc_id": "14039781", "n_citations": 215, "n_key_citations": 6, "score": 0, "title": "Superlattice Induced Insulating States and Valley Protected Orbits in Twisted Bilayer Graphene.", "venue": "Physical review letters", "year": 2016 }, { "abstract": "A pseudopotential complex band structure approach is used to investigate the valence band electronic structure of GaAs/AlGaAs superlattice. The form of the subband energy spectrum and wavefunctions is studied within subbands that exhibit a changeover between heavy and light hole character as a function of the superlattice wave vector and period; the results are compared with a simple position dependent effective mass theory.", "author_names": [ "Stuart Brand", "Scott Monaghan", "Paul P Szydlik" ], "corpus_id": 96266316, "doc_id": "96266316", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Calculations of electronic states in the valence band of (100) GaAs/AlGaAs superlattices", "venue": "", "year": 1987 }, { "abstract": "In the present study we investigate the effect of component interdiffusion across the interfaces on the electronic structure of a quantum well embedded in a short period superlattice. We calculate the energies of the bound states for an 18 monolayer (5 nm) thick GaAs quantum well embedded in an (AlAs)4/(GaAs)8 superlattice in comparison with two AlxGa1 xAs/GaAs (x 1 and 0.33) single quantum wells with the same thickness. The calculations are made within the framework of the envelope function approximation. The behaviour of the lowest electron and hole bound states is studied for values of the diffusion length from 0 to 4 monolayers. The contribution of the X point conduction band minima to the electronic structure is discussed. The calculated transition energies are shown to be in agreement with photoluminescence spectra of such structures. The presented approach can be used to assess the effect of the component intermixing on the electronic structure of various complex multilayered systems.", "author_names": [ "N Shtinkov", "Vesselin Donchev", "K G Germanova", "Hristo Kolev" ], "corpus_id": 95491955, "doc_id": "95491955", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Electronic structure of quantum wells embedded in short period superlattices with graded interfaces", "venue": "", "year": 2000 }, { "abstract": "Much understanding of the electronic and optical properties of a semiconductor superlattice can be obtained by relating the superlattice electronic wave functions and band structure to those of the two bulk semiconductors from which it is constructed. In this paper, the relationship is studied within the framework of the empirical tight binding model, which is solved using the reduced Hamiltonian technique. The superlattice wave functions are described as linear combinations of bulk Bloch functions with complex wave vectors, twenty (including spin) for each of the two constituent materials. The bulk Bloch function composition of the superlattice wave function is studied as a function of layer thickness, alloy composition, and energy. The GaAs \\mathrm{Ga}}_{1\\mathrm{\\ensuremath{ \\mathrm{x}\\mathrm{Al}}_{\\mathrm{x}$As and InAs GaSb superlattices are examined in detail. Comparisons with simpler Kronig Penney and envelope function models are made. It is found that the lowest superlattice conduction band states are primarily derived from the expected bulk states with wave vectors near the center of the Brillouin zone, with a small admixture of zone edge components. The energies and general form of the wave functions are modified only slightly, except close to the interfaces. There, the admixture can significantly affect the interfacial boundary conditions beyond those employed by commonly used envelope function approximations. Valence band states are more complicated in that the superlattice periodic potential mixes the bulk heavy hole, light hole, and spin orbit split off bands, even at the superlattice Brillouin zone center. Crossover effects occur in which a given superlattice subband can have a varying proportion of light hole like or heavy hole like character depending on superlattice layer thickness. The dispersion of the subbands away from the zone center also causes the mixing of bands and results in modifications of the superlattice band structure as compared with band structures produced by simpler models.", "author_names": [ "" ], "corpus_id": 28088961, "doc_id": "28088961", "n_citations": 176, "n_key_citations": 0, "score": 0, "title": "Band mixing in semiconductor superlattices.", "venue": "Physical review. B, Condensed matter", "year": 1985 }, { "abstract": "Along with the growing interest in semiconductor superlattices, various theoretical schemes have been proposed to study the nature of the electronic states within these structures. The work presented here highlights a new method to investigate the electronic and optical properties of semiconductor superlattices. The backbone of the theory rests on a realistic description of the complex k band structure of the constituent semiconductors coupled with a suitable set of boundary conditions for the superlattice wave function. The bulk Bloch solutions, propagating and evanescent, in each semiconductor are described within a full zone k p Hamiltonian that provides an accurate description of the solutions up to the first Brillouin zone edge. An attractive feature of the present treatment is that the complex k bulk Bloch solutions of each constituent semiconductor are expanded on the same set of zone center basis functions. A new technique for constructing the k p Hamiltonian of each constituent semiconductor", "author_names": [ "Christian Mailhiot", "T C Mcgill", "Darryl L Smith" ], "corpus_id": 121714448, "doc_id": "121714448", "n_citations": 18, "n_key_citations": 0, "score": 0, "title": "New approach to the k p theory of semiconductor superlattices", "venue": "", "year": 1984 }, { "abstract": "", "author_names": [ "Lama Khalil", "Evangelos Papalazarou", "Marco Caputo", "Niloufar Nilforoushan", "Luca Perfetti", "Amina Taleb-Ibrahimi", "V Kandyba", "Alexei Barinov", "Quinn D Gibson", "Robert J Cava", "Marino Marsi" ], "corpus_id": 125695173, "doc_id": "125695173", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Electronic band structure for occupied and unoccupied states of the natural topological superlattice phase Sb2Te", "venue": "", "year": 2017 }, { "abstract": "A mismatch of atomic registries between single layer transition metal dichalcogenides (TMDs) in a two dimensional van der Waals heterostructure produces a moire superlattice with a periodic potential, which can be fine tuned by introducing a twist angle between the materials. This approach is promising both for controlling the interactions between the TMDs and for engineering their electronic band structures, yet direct observation of the changes to the electronic structure introduced with varying twist angle has so far been missing. Here, we probe heterobilayers comprised of singlelayer MoS2 and WS2 with twist angles of (2.0+ 0.5) (13.0+ 0.5) and (20.0+ 0.5) and investigate the differences in their electronic band structure using micro focused angle resolved photoemission spectroscopy. We find strong interlayer hybridization between MoS2 and WS2 electronic states at the G point of the Brillouin zone, leading to a transition from a direct bandgap in the single layer to an indirect gap in the heterostructure. Replicas of the hybridized states are observed at the centre of twist angle dependent moire mini Brillouin zones. We confirm that these replica features arise from the inherent moire potential by comparing our experimental observations with density functional theory calculations of the superlattice dispersion. Our direct visualization of these features underscores the potential of using twisted heterobilayer semiconductors to engineer hybrid electronic states and superlattices that alter the electronic and optical properties of 2D heterostructures.", "author_names": [ "Alfred J H Jones", "Ryan Muzzio", "Sahar Pakdel", "Deepnarayan Biswas", "Davide Curcio", "Nicola Lanata", "Philip Hofmann", "Kathleen M McCreary", "Berend T Jonker", "Kenji Watanabe", "Takashi Taniguchi", "Simranjeet Singh", "Roland J Koch", "Chris Jozwiak", "Eli Rotenberg", "Aaron Bostwick", "Jill A Miwa", "Jyoti Katoch", "Soren Ulstrup" ], "corpus_id": 235265641, "doc_id": "235265641", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Visualizing band structure hybridization and superlattice effects in twisted MoS$_2$/WS$_2$ heterobilayers", "venue": "", "year": 2021 }, { "abstract": "It is natural to characterize materials in transport junctions by their conductance length dependence, b. Theoretical estimations of b are made employing two primary theories: complex band structure and density functional theory (DFT) Landauer transport. It has previously been shown that the b value derived from total Landauer transmission can be related to the b value from the smallest |ki| complex band; however, it is an open question whether there is a deeper relationship between the two. Here we probe the details of the relationship between transmission and complex band structure, in this case individual eigenchannel transmissions and different complex bands. We present calculations of decay constants for the two most conductive states as determined by complex band structure and standard DFT Landauer transport calculations for one semi conductor and two molecular junctions. The molecular junctions show that both the length dependence of the total transmission and the individual transmission eigenvalues can be, almost always, found through the complex band structure. The complex band structure of the semi conducting material, however, does not predict the length dependence of the total transmission but only of the individual channels, at some k points, due to multiple channels contributing to transmission. We also observe instances of vertical bands, some of which are the smallest |ki| complex bands, that do not contribute to transport. By understanding the deeper relationship between complex bands and individual transmission eigenchannels, we can make a general statement about when the previously accepted wisdom linking transmission and complex band structure will fail, namely, when multiple channels contribute significantly to the transmission.", "author_names": [ "Anders Jensen", "Mikkel Strange", "S Smidstrup", "Kurt Stokbro", "Gemma C Solomon", "Matthew G Reuter" ], "corpus_id": 23523237, "doc_id": "23523237", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Complex band structure and electronic transmission eigenchannels.", "venue": "The Journal of chemical physics", "year": 2017 }, { "abstract": "Nanostructured TiN(001) dot/MgO(001) 4 x 4 and 5 x 5 superlattices based on a repeated slab model have been investigated. The electronic states of TiN(001) dot/MgO(001) 4 x 4 and 5 x 5 superlattices were obtained by using the total energy pseudopotential method. The internal atomic coordinates in a unit cell were fully relaxed. We consider two types of TiN dot structures as rectangular and rectangular parallelepiped. They all correspond to semiconductor, although relaxed rectangular parallelepiped TiN(001) dot/MgO(001) 2 x 2 and 3 x 3 superlattices correspond to metallicity. A bandgap value of the rectangular TiN(001) dot/MgO(001) superlattice increases with increasing the size of the MgO substrate, although the difference in the band gap between 4 x 4 and 5 x 5 is small at approximately 0.01 eV. Their electronic properties depend on the shape of the TiN dot and the size of the MgO substrate. The bandgap value is corrected by using a generalized density functional theory.", "author_names": [ "Kazuaki Kobayashi", "Hirokazu Takaki", "Masato Shimono", "Nobuhiko P Kobayashi", "Kenji Hirose" ], "corpus_id": 127411340, "doc_id": "127411340", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Electronic band structure of TiN/MgO 4 x 4 and 5 x 5 nanostructures", "venue": "Japanese Journal of Applied Physics", "year": 2019 } ]

[ { "abstract": "With advances in exfoliation and synthetic techniques, atomically thin films of semiconducting transition metal dichalcogenides have recently been isolated and characterized. Their two dimensional structure, coupled with a direct band gap in the visible portion of the electromagnetic spectrum, suggests suitability for digital electronics and optoelectronics. Toward that end, several classes of high performance devices have been reported along with significant progress in understanding their physical properties. Here, we present a review of the architecture, operating principles, and physics of electronic and optoelectronic devices based on ultrathin transition metal dichalcogenide semiconductors. By critically assessing and comparing the performance of these devices with competing technologies, the merits and shortcomings of this emerging class of electronic materials are identified, thereby providing a roadmap for future development.", "author_names": [ "Deep Jariwala", "Vinod K Sangwan", "Lincoln J Lauhon", "Tobin J Marks", "Mark C Hersam" ], "corpus_id": 5409236, "doc_id": "5409236", "n_citations": 1757, "n_key_citations": 10, "score": 1, "title": "Emerging device applications for semiconducting two dimensional transition metal dichalcogenides.", "venue": "ACS nano", "year": 2014 }, { "abstract": "The emerging system of atomically thin materials with only a few atomic layer thickness opens the new research fields of optical science and device applications. The optically generated bound electron hole pairs (excitons and charged excitons) contribute to the novel optical properties in semiconducting atomically thin materials of monolayer transition metal dichalcogenides called as \"beyond graphene\" We describe our recent studies on novel optical science and application in atomically thin semiconducting transition metal dichalcogenides.", "author_names": [ "Kazunaii Matsuda" ], "corpus_id": 40379573, "doc_id": "40379573", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Optical properties and application of atomically thin two dimensional materials", "venue": "2017 24th International Workshop on Active Matrix Flatpanel Displays and Devices (AM FPD)", "year": 2017 }, { "abstract": "Recent experimental efforts in investigating low dimensional nanomaterials have spanned significantly beyond carbon nanotube (CNT) and graphene, which are often considered hallmarks of one and two dimensional (1&2D) nanostructures. Emerging layered nanomaterials, such as transition metal dichalcogenides (TMDC) and black phosphorus (P) have enabled new device functions and potential applications thanks to their intriguing material properties unavailable in CNT and graphene. In particular, nanoelectromechanical systems (NEMS) based on these new nanostructures exhibit new and interesting device properties. This paper describes the recent progresses in exploring and engineering atomically thin semiconducting crystals into a new class of two dimensional nanoelectromechanical systems, which hold promises for building novel nanoscale transducers. Exploration of resonant NEMS based on molybdenum disulfide (MoS2) reveals in these new nanoscale systems very broad dynamic range, rich nonlinear dynamics, and outstanding electrical tunability. Further, recent investigations show that black P NEMS offer the unique opportunity for harnessing the strong mechanical anisotropy in this nanocrystal composed of corrugated atomic sheets, demonstrating potential towards new device functions and applications that are unavailable to CNT and graphene based devices and systems.", "author_names": [ "Max Zenghui Wang" ], "corpus_id": 43031324, "doc_id": "43031324", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Nanoelectromechanical systems based on low dimensional nanomaterials: Beyond carbon nanotube and graphene nanomechanical resonators a brief review", "venue": "2016 IEEE 16th International Conference on Nanotechnology (IEEE NANO)", "year": 2016 }, { "abstract": "Two dimensional (2D) semiconducting transition metal dichalcogenides (TMDCs) and black phosphorus (BP) have beneficial electronic, optical, and physical properties at the few layer limit. As atomically thin materials, 2D TMDCs and BP are highly sensitive to their environment and chemical modification, resulting in a strong dependence of their properties on substrate effects, intrinsic defects, and extrinsic adsorbates. Furthermore, the integration of 2D semiconductors into electronic and optoelectronic devices introduces unique challenges at metal semiconductor and dielectric semiconductor interfaces. Here, we review emerging efforts to understand and exploit chemical effects to influence the properties of 2D TMDCs and BP. In some cases, surface chemistry leads to significant degradation, thus necessitating the development of robust passivation schemes. On the other hand, appropriately designed chemical modification can be used to beneficially tailor electronic properties, such as controlling doping levels and charge carrier concentrations. Overall, chemical methods allow substantial tunability of the properties of 2D TMDCs and BP, thereby enabling significant future opportunities to optimize performance for device applications.", "author_names": [ "Christopher R Ryder", "Joshua D Wood", "Spencer A Wells", "Mark C Hersam" ], "corpus_id": 206701061, "doc_id": "206701061", "n_citations": 168, "n_key_citations": 1, "score": 0, "title": "Chemically Tailoring Semiconducting Two Dimensional Transition Metal Dichalcogenides and Black Phosphorus.", "venue": "ACS nano", "year": 2016 }, { "abstract": "Abstract It is known that only in plane piezoelectricity exists in pristine two dimensional (2D) transition metal dichalcogenides (TMDs) In this study, we demonstrate the creation of strong out of plane piezoelectricity in semiconducting 2H MoTe2 flakes by an artificial atomic scale symmetry breaking. The atomic scale symmetry breaking associated with flexoelectricity was realized through Te vacancy formation by a simple thermal annealing of the 2D TMDs. The strong out of plane piezoelectricity was experimentally measured and confirmed by theoretical calculations. This strategy of atomic scale symmetry modulation for out of plane piezoelectricity can be easily applied to a broader class of 2D TMD materials that have not been used for applications with out of plane piezoelectricity. Accordingly, it can stimulate the expansion of practical energy device applications with 2D TMD materials.", "author_names": [ "Sera Kim", "Daehee Seol" ], "corpus_id": 139480969, "doc_id": "139480969", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Atomic scale symmetry breaking for out of plane piezoelectricity in two dimensional transition metal dichalcogenides", "venue": "Nano Energy", "year": 2019 }, { "abstract": "Two dimensional (2D) semiconductors, such as ultrathin layers of transition metal dichalcogenides (TMDs) offer a unique combination of electronic, optical and mechanical properties, and hold potential to enable a host of new device applications spanning from flexible/wearable (opto)electronics to energy harvesting and sensing technologies. A critical requirement for developing practical and reliable electronic devices based on semiconducting TMDs consists in achieving a full control over their charge carrier polarity and doping. Inconveniently, such a challenging task cannot be accomplished by means of well established doping techniques (e.g. ion implantation and diffusion) which unavoidably damage the 2D crystals resulting in degraded device performances. Nowadays, a number of alternatives are being investigated, including various (supra)molecular chemistry approaches relying on the combination of 2D semiconductors with electroactive donor/acceptor molecules. As yet, a large variety of molecular systems have been utilized for functionalizing 2D TMDs via both covalent and non covalent interactions. Such research endeavours enabled not only the tuning of the charge carrier doping but also the engineering of the optical, electronic, magnetic, thermal and sensing properties of semiconducting TMDs for specific device applications. Here, we will review the most enlightening recent advancements in experimental (supra)molecular chemistry methods for tailoring the properties of atomically thin TMDs in the form of substrate supported or solution dispersed nanosheets and we will discuss the opportunities and the challenges towards the realization of novel hybrid materials and devices based on 2D semiconductors and molecular systems.", "author_names": [ "Simone Bertolazzi", "Marco Gobbi", "Yuda Zhao", "Claudia Backes", "Paolo Samori" ], "corpus_id": 51717071, "doc_id": "51717071", "n_citations": 97, "n_key_citations": 0, "score": 0, "title": "Molecular chemistry approaches for tuning the properties of two dimensional transition metal dichalcogenides.", "venue": "Chemical Society reviews", "year": 2018 }, { "abstract": "Abstract Transition metal dichalcogenides (TMDCs) have attracted significant attention for their great potential in nano energy. TMDC layered materials represent a diverse and largely untapped source of 2D systems. High quality TMDC layers with an appropriate size, variable thickness, superior electronic and optical properties can be produced by the exfoliation or vapor phase deposition method. Semiconducting TMDC monolayers have been demonstrated feasible for various energy related applications, where their electronic properties and uniquely high surface areas offer opportunities for various applications such as nano generators, green electronics, electrocatalytic hydrogen generation and energy storage. In this review, we start from the structure, properties and preparation, followed by detailed discussions on the development of TMDC based nano energy applications.", "author_names": [ "Henan Li", "Yumeng Shi", "Ming-Hui Chiu", "Lain-Jong Li" ], "corpus_id": 137051812, "doc_id": "137051812", "n_citations": 148, "n_key_citations": 1, "score": 0, "title": "Emerging energy applications of two dimensional layered transition metal dichalcogenides", "venue": "", "year": 2015 }, { "abstract": "The recent exploration of semiconducting two dimensional (2D) transition metal dichalcogenides (TMDs) with atomic thickness has taken both the scientific and technological communities by storm. Extensively investigated TMD that are accessible by large scale synthetic methods materials are remarkably stable, such as MoS2 and WSe2 They allow superior gate control due to their 2D nature and favorable electronic transport properties, thus suggesting a bright future for digital and RF electronics. In this review, the latest developments in the controlled synthesis of large scale TMDs are firstly introduced by discussing various approaches. The major obstacles that must be overcome to achieve wafer scale, uniform, and high quality TMD films for practical electronic applications are included. Advances in the electronic transport studies of TMDs are presented, such as doping, contact engineering, and mobility improvement, which contribute to overall device performance. A perspective and a look at the future for this field is provided in closing.", "author_names": [ "Xiongfei Song", "Zhongxun Guo", "Qiaochu Zhang", "Peng Zhou", "Wenzhong Bao", "David-Wei Zhang" ], "corpus_id": 22022281, "doc_id": "22022281", "n_citations": 33, "n_key_citations": 0, "score": 0, "title": "Progress of Large Scale Synthesis and Electronic Device Application of Two Dimensional Transition Metal Dichalcogenides.", "venue": "Small", "year": 2017 }, { "abstract": "Two dimensional (2D) materials have become a growing subject in the last 15 years mainly due to the isolation of graphene, which created a completely different class of material based on its unique, monolayer design. Since then, various stable materials of few atoms thick are showing emerging capabilities in optical electronics and photonics. Semiconducting monolayers of transition metal dichalcogenides (TMDs) such as MoS2, Mo1 xWxS2, and WS2 exhibit direct electronic band gaps; bulk crystals display indirect band gaps. Interestingly, these 2D materials show significant light interaction over a broad bandwidth ranging from infrared to ultraviolet wavelengths. The materials allow photodetection in this bandwidth without the need of cooling, thus creating new potential for uncooled detection. In this review, we discuss various 2D materials and their interaction with light for photodetection applications.", "author_names": [ "Andrew Voshell", "Mauricio Terrones", "Mukti Rana" ], "corpus_id": 139283560, "doc_id": "139283560", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Review of optical properties of two dimensional transition metal dichalcogenides", "venue": "Optical Engineering Applications", "year": 2018 }, { "abstract": "The remarkable properties of graphene have renewed interest in inorganic, two dimensional materials with unique electronic and optical attributes. Transition metal dichalcogenides (TMDCs) are layered materials with strong in plane bonding and weak out of plane interactions enabling exfoliation into two dimensional layers of single unit cell thickness. Although TMDCs have been studied for decades, recent advances in nanoscale materials characterization and device fabrication have opened up new opportunities for two dimensional layers of thin TMDCs in nanoelectronics and optoelectronics. TMDCs such as MoS(2) MoSe(2) WS(2) and WSe(2) have sizable bandgaps that change from indirect to direct in single layers, allowing applications such as transistors, photodetectors and electroluminescent devices. We review the historical development of TMDCs, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.", "author_names": [ "Qing Hua Wang", "Kourosh Kalantar-zadeh", "Andras Kis", "Jonathan N Coleman", "Michael S Strano" ], "corpus_id": 6261931, "doc_id": "6261931", "n_citations": 10034, "n_key_citations": 84, "score": 0, "title": "Electronics and optoelectronics of two dimensional transition metal dichalcogenides.", "venue": "Nature nanotechnology", "year": 2012 } ]

[ { "abstract": "Ultrathin two dimensional nanosheets of layered transition metal dichalcogenides (TMDs) are fundamentally and technologically intriguing. In contrast to the graphene sheet, they are chemically versatile. Mono or few layered TMDs obtained either through exfoliation of bulk materials or bottom up syntheses are direct gap semiconductors whose bandgap energy, as well as carrier type (n or p type) varies between compounds depending on their composition, structure and dimensionality. In this Review, we describe how the tunable electronic structure of TMDs makes them attractive for a variety of applications. They have been investigated as chemically active electrocatalysts for hydrogen evolution and hydrosulfurization, as well as electrically active materials in opto electronics. Their morphologies and properties are also useful for energy storage applications such as electrodes for Li ion batteries and supercapacitors.", "author_names": [ "Manish Chhowalla", "Hyeon Suk Shin", "Goki Eda", "Lain-Jong Li", "Kian Ping Loh", "Hua Zhang" ], "corpus_id": 205291228, "doc_id": "205291228", "n_citations": 5976, "n_key_citations": 50, "score": 0, "title": "The chemistry of two dimensional layered transition metal dichalcogenide nanosheets.", "venue": "Nature chemistry", "year": 2013 }, { "abstract": "Supervised learning on molecules has incredible potential to be useful in chemistry, drug discovery, and materials science. Luckily, several promising and closely related neural network models invariant to molecular symmetries have already been described in the literature. These models learn a message passing algorithm and aggregation procedure to compute a function of their entire input graph. At this point, the next step is to find a particularly effective variant of this general approach and apply it to chemical prediction benchmarks until we either solve them or reach the limits of the approach. In this paper, we reformulate existing models into a single common framework we call Message Passing Neural Networks (MPNNs) and explore additional novel variations within this framework. Using MPNNs we demonstrate state of the art results on an important molecular property prediction benchmark; these results are strong enough that we believe future work should focus on datasets with larger molecules or more accurate ground truth labels.", "author_names": [ "Justin Gilmer", "Samuel S Schoenholz", "Patrick F Riley", "Oriol Vinyals", "George E Dahl" ], "corpus_id": 9665943, "doc_id": "9665943", "n_citations": 2364, "n_key_citations": 341, "score": 0, "title": "Neural Message Passing for Quantum Chemistry", "venue": "ICML", "year": 2017 }, { "abstract": "", "author_names": [ "John R Rumble" ], "corpus_id": 199645733, "doc_id": "199645733", "n_citations": 922, "n_key_citations": 91, "score": 1, "title": "CRC Handbook of Chemistry and Physics", "venue": "", "year": 2019 }, { "abstract": "Background Metal organic frameworks (MOFs) are made by linking inorganic and organic units by strong bonds (reticular synthesis) The flexibility with which the constituents' geometry, size, and functionality can be varied has led to more than 20,000 different MOFs being reported and studied within the past decade. The organic units are ditopic or polytopic organic carboxylates (and other similar negatively charged molecules) which, when linked to metal containing units, yield architecturally robust crystalline MOF structures with a typical porosity of greater than 50% of the MOF crystal volume. The surface area values of such MOFs typically range from 1000 to 10,000 m2/g, thus exceeding those of traditional porous materials such as zeolites and carbons. To date, MOFs with permanent porosity are more extensive in their variety and multiplicity than any other class of porous materials. These aspects have made MOFs ideal candidates for storage of fuels (hydrogen and methane) capture of carbon dioxide, and catalysis applications, to mention a few. Metal organic framework (MOF) structures are amenable to expansion and incorporation of multiple functional groups within their interiors. (A) The isoreticular expansion of MOFs maintains the network's topology by using an expanded version of the parent organic linker. Examples of catalysis in MOFs are shown in the large space created by IRMOF 74 XI; Me is a methyl group. (B) Conceptual illustration of a multivariate MOF (MTV MOF) whose pores are decorated by heterogeneous mixtures of functionalities that arrange in specific sequences. (Background) Optical image of zeolitic imidazolate framework (ZIF) crystals. Advances The ability to vary the size and nature of MOF structures without changing their underlying topology gave rise to the isoreticular principle and its application in making MOFs with the largest pore aperture (98 A) and lowest density (0.13 g/cm3) This has allowed for the selective inclusion of large molecules (e.g. vitamin B12) and proteins (e.g. green fluorescent protein) and the exploitation of the pores as reaction vessels. Along these lines, the thermal and chemical stability of many MOFs has made them amenable to postsynthetic covalent organic and metal complex functionalization. These capabilities enable substantial enhancement of gas storage in MOFs and have led to their extensive study in the catalysis of organic reactions, activation of small molecules (hydrogen, methane, and water) gas separation, biomedical imaging, and proton, electron, and ion conduction. At present, methods are being developed for making nanocrystals and supercrystals of MOFs for their incorporation into devices. Outlook The precise control over the assembly of MOFs is expected to propel this field further into new realms of synthetic chemistry in which far more sophisticated materials may be accessed. For example, materials can be envisaged as having (i) compartments linked together to operate separately, yet function synergistically; (ii) dexterity to carry out parallel operations; (iii) ability to count, sort, and code information; and (iv) capability of dynamics with high fidelity. Efforts in this direction are already being undertaken through the introduction of a large number of different functional groups within the pores of MOFs. This yields multivariate frameworks in which the varying arrangement of functionalities gives rise to materials that offer a synergistic combination of properties. Future work will involve the assembly of chemical structures from many different types of building unit, such that the structures' function is dictated by the heterogeneity of the specific arrangement of their constituents. Strategies for Metal Organic Frameworks Metal organic frameworks are porous materials that can exhibit very high surface areas that have potential for applications such as gas storage and separation, as well as catalysis. Furukawa et al. (1230444) review the structures devised so far and discuss the design strategies that allow families of materials to be synthesized and modified with similar framework topology but vary in pore size and type of functional groups present on the linkers. Crystalline metal organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.", "author_names": [ "Hiroyasu Furukawa", "Kyle E Cordova", "M O'keeffe", "Omar M Yaghi" ], "corpus_id": 18400106, "doc_id": "18400106", "n_citations": 7036, "n_key_citations": 13, "score": 0, "title": "The Chemistry and Applications of Metal Organic Frameworks", "venue": "Science", "year": 2013 }, { "abstract": "1 The Atmosphere. 2 Atmospheric Trace Constituents. 3 Chemical Kinetics. 4 Atmospheric Radiation and Photochemistry. 5 Chemistry of the Stratosphere. 6 Chemistry of the Troposphere. 7 Chemistry of the Atmospheric Aqueous Phase. 8 Properties of the Atmospheric Aerosol. 9 Dynamics of Single Aerosol Particles. 10 Thermodynamics of Aerosols. 11 Nucleation. 12 Mass Transfer Aspects of Atmospheric Chemistry. 13 Dynamics of Aerosol Populations. 14 Organic Atmospheric Aerosols. 15 Interaction of Aerosols with Radiation. 16 Meteorology of the Local Scale. 17 Cloud Physics. 18 Atmospheric Diffusion. 19 Dry Deposition. 20 Wet Deposition. 21 General Circulation of the Atmosphere. 22 Global Cycles: Sulfur and Carbon. 23 Climate and Chemical Composition of the Atmosphere. 24 Aerosols and Climate. 25 Atmospheric Chemical Transport Models. 26 Statistical Models.", "author_names": [ "John H Seinfeld", "Spyros N Pandis" ], "corpus_id": 98232768, "doc_id": "98232768", "n_citations": 12028, "n_key_citations": 1571, "score": 0, "title": "Atmospheric Chemistry and Physics: From Air Pollution to Climate Change", "venue": "", "year": 1997 }, { "abstract": "The chemistry of graphene oxide is discussed in this critical review. Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure. Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene like materials, is also discussed. This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)", "author_names": [ "Daniel R Dreyer", "Sungjin Park", "Christopher W Bielawski", "Rodney S Ruoff" ], "corpus_id": 18364219, "doc_id": "18364219", "n_citations": 8579, "n_key_citations": 102, "score": 0, "title": "The chemistry of graphene oxide.", "venue": "Chemical Society reviews", "year": 2010 }, { "abstract": "CRC handbook of chemistry and physics CRC handbook of chemistry and physics khtbkhnh mrkhzy dnshgh `lwm pzshkhy thrn", "author_names": [ "William M Haynes" ], "corpus_id": 98796437, "doc_id": "98796437", "n_citations": 17052, "n_key_citations": 963, "score": 0, "title": "CRC Handbook of Chemistry and Physics", "venue": "", "year": 1990 }, { "abstract": "", "author_names": [ "Paul J Flory" ], "corpus_id": 94138368, "doc_id": "94138368", "n_citations": 14683, "n_key_citations": 350, "score": 0, "title": "Principles of polymer chemistry", "venue": "", "year": 1953 }, { "abstract": "Cyclooxygenase 2 isozyme is a promising anti inflammatory drug target, and overexpression of this enzyme is also associated with several cancers and neurodegenerative diseases. The amino acid sequence and structural similarity between inducible cyclooxygenase 2 and housekeeping cyclooxygenase 1 isoforms present a significant challenge to design selective cyclooxygenase 2 inhibitors. Herein, we describe the use of the cyclooxygenase 2 active site as a reaction vessel for the in situ generation of its own highly specific inhibitors. Multi component competitive binding studies confirmed that the cyclooxygenase 2 isozyme can judiciously select most appropriate chemical building blocks from a pool of chemicals to build its own highly potent inhibitor. Herein, with the use of kinetic target guided synthesis, also termed as in situ click chemistry, we describe the discovery of two highly potent and selective cyclooxygenase 2 isozyme inhibitors. The in vivo anti inflammatory activity of these two novel small molecules is significantly higher than that of widely used selective cyclooxygenase 2 inhibitors.Traditional inflammation and pain relief drugs target both cyclooxygenase 1 and 2 (COX 1 and COX 2) causing severe side effects. Here, the authors use in situ click chemistry to develop COX 2 specific inhibitors with high in vivo anti inflammatory activity.", "author_names": [ "Atul Bhardwaj", "Jatinder Kaur", "Melinda Wuest", "Frank Wuest" ], "corpus_id": 3465336, "doc_id": "3465336", "n_citations": 2937, "n_key_citations": 0, "score": 0, "title": "In situ click chemistry generation of cyclooxygenase 2 inhibitors", "venue": "Nature Communications", "year": 2016 }, { "abstract": "", "author_names": [ "David R Lide" ], "corpus_id": 104048178, "doc_id": "104048178", "n_citations": 9908, "n_key_citations": 264, "score": 0, "title": "Handbook of Chemistry and Physics", "venue": "", "year": 1992 } ]

[ { "abstract": "Topological insulators are new states of quantum matter which cannot be adiabatically connected to conventional insulators and semiconductors. They are characterized by a full insulating gap in the bulk and gapless edge or surface states which are protected by time reversal symmetry. These topological materials have been theoretically predicted and experimentally observed in a variety of systems, including HgTe quantum wells, BiSb alloys, and Bi2Te3 and Bi2Se3 crystals. Theoretical models, materials properties, and experimental results on two dimensional and three dimensional topological insulators are reviewed, and both the topological band theory and the topological field theory are discussed. Topological superconductors have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions. The theory of topological superconductors is reviewed, in close analogy to the theory of topological insulators.", "author_names": [ "Xiao-liang Qi", "Shou-Cheng Zhang" ], "corpus_id": 118373714, "doc_id": "118373714", "n_citations": 7037, "n_key_citations": 128, "score": 0, "title": "Topological insulators and superconductors", "venue": "", "year": 2011 }, { "abstract": "Topological insulators are electronic materials that have a bulk band gap like an ordinary insulator but have protected conducting states on their edge or surface. These states are possible due to the combination of spin orbit interactions and time reversal symmetry. The two dimensional (2D) topological insulator is a quantum spin Hall insulator, which is a close cousin of the integer quantum Hall state. A three dimensional (3D) topological insulator supports novel spin polarized 2D Dirac fermions on its surface. In this Colloquium the theoretical foundation for topological insulators and superconductors is reviewed and recent experiments are described in which the signatures of topological insulators have been observed. Transport experiments on \\mathrm{Hg}\\mathrm{Te}\\mathrm{Cd}\\mathrm{Te} quantum wells are described that demonstrate the existence of the edge states predicted for the quantum spin Hall insulator. Experiments on \\mathrm{Bi}}_{1\\ensuremath{ }x}\\mathrm{Sb}}_{x} \\mathrm{Bi}}_{2}\\mathrm{Se}}_{3} \\mathrm{Bi}}_{2}\\mathrm{Te}}_{3} and \\mathrm{Sb}}_{2}\\mathrm{Te}}_{3} are then discussed that establish these materials as 3D topological insulators and directly probe the topology of their surface states. Exotic states are described that can occur at the surface of a 3D topological insulator due to an induced energy gap. A magnetic gap leads to a novel quantum Hall state that gives rise to a topological magnetoelectric effect. A superconducting energy gap leads to a state that supports Majorana fermions and may provide a new venue for realizing proposals for topological quantum computation. Prospects for observing these exotic states are also discussed, as well as other potential device applications of topological insulators.", "author_names": [ "M Zahid Hasan", "C L Kane" ], "corpus_id": 16066223, "doc_id": "16066223", "n_citations": 10078, "n_key_citations": 176, "score": 0, "title": "Colloquium Topological insulators", "venue": "", "year": 2010 }, { "abstract": "We study three dimensional generalizations of the quantum spin Hall (QSH) effect. Unlike two dimensions, where a single Z2 topological invariant governs the effect, in three dimensions there are 4 invariants distinguishing 16 phases with two general classes: weak (WTI) and strong (STI) topological insulators. The WTI are like layered 2D QSH states, but are destroyed by disorder. The STI are robust and lead to novel \"topological metal\" surface states. We introduce a tight binding model which realizes the WTI and STI phases, and we discuss its relevance to real materials, including bismuth.", "author_names": [ "Liang Fu", "C L Kane", "Eugene J Mele" ], "corpus_id": 6037351, "doc_id": "6037351", "n_citations": 2476, "n_key_citations": 80, "score": 0, "title": "Topological insulators in three dimensions.", "venue": "Physical review letters", "year": 2007 }, { "abstract": "Topological insulators are materials with a bulk excitation gap generated by the spin orbit interaction that are different from conventional insulators. This distinction is characterized by {Z}_{2} topological invariants, which characterize the ground state. In two dimensions, there is a single {Z}_{2} invariant that distinguishes the ordinary insulator from the quantum spin Hall phase. In three dimensions, there are four {Z}_{2} invariants that distinguish the ordinary insulator from `weak' and `strong' topological insulators. These phases are characterized by the presence of gapless surface (or edge) states. In the two dimensional quantum spin Hall phase and the three dimensional strong topological insulator, these states are robust and are insensitive to weak disorder and interactions. In this paper, we show that the presence of inversion symmetry greatly simplifies the problem of evaluating the {Z}_{2} invariants. We show that the invariants can be determined from the knowledge of the parity of the occupied Bloch wave functions at the time reversal invariant points in the Brillouin zone. Using this approach, we predict a number of specific materials that are strong topological insulators, including the semiconducting alloy \\mathrm{Bi}}_{1\\ensuremath{ }x}\\mathrm{Sb}}_{x} as well as \\ensuremath{\\alpha}\\text{\\ensuremath{ \\mathrm{Sn} and HgTe under uniaxial strain. This paper also includes an expanded discussion of our formulation of the topological insulators in both two and three dimensions, as well as implications for experiments.", "author_names": [ "Liang Fu", "C L Kane" ], "corpus_id": 15011491, "doc_id": "15011491", "n_citations": 2250, "n_key_citations": 73, "score": 0, "title": "Topological insulators with inversion symmetry", "venue": "", "year": 2007 }, { "abstract": "anyone with a healthy fear of sticking their fingers into a plug socket will know, the behaviour of electrons in different materials varies dramatically. The first \" electronic phases \" of matter to be defined were the electrical conductor and insulator, and then came the semiconductor, the magnet and more exotic phases such as the superconductor. Recent work has, however now uncovered a new electronic phase called a topological insulator. Putting the name to one side for now, the meaning of which will become clear later, what is really getting everyone excited is the behaviour of materials in this phase. Strangely, they can insulate on the inside but conduct on the outside acting like a thick plastic cable covered with a layer of metal, except that the material is actually the same throughout. What is more, the conducting electrons arrange themselves into spin up electrons travelling in one direction and spin down electrons travelling in the other; this \" spin current \" is a milestone in the realization of practical \" spintronics \" Topological insulators have a rather unusual history because unlike almost every other exotic phase of matter they were characterized theoretically before being discovered experimentally. Both of the present authors, among others, were involved in that early work, which was based on the band theory of solids the standard quantum mechanical framework for understanding the electronic properties of materials. We showed two things. First, special edge states (in 2D objects) or surface states (in 3D objects) allow electrons to conduct at the surface of a material that otherwise behaves as an insulator. Second, these states necessarily occur when the band structure has a certain property a value associated with an abstract quantity called the topology (more about this later) For one of us (CK) it was an attempt to contribute to the theory of graphene the one atom thick sheets of carbon celebrated by the 2010 Nobel prize that inspired these new ideas about topology. But only when topological insulators were discovered experimentally in 2007 did the attention of the condensed matter physics community become firmly focused on this new class of materials. A related topo logical property known as the quantum Hall effect had already been found in 2D ribbons in the early 1980s, but the discovery of the first example of a 3D topologi cal phase reignited that earlier interest. Given that the 3D topological insulators", "author_names": [ "Yize Jin", "Lu Zheng", "" ], "corpus_id": 6085616, "doc_id": "6085616", "n_citations": 1303, "n_key_citations": 76, "score": 1, "title": "Topological Insulators", "venue": "", "year": 2013 }, { "abstract": "When electrons are subject to a large external magnetic field, the conventional charge quantum Hall effect dictates that an electronic excitation gap is generated in the sample bulk, but metallic conduction is permitted at the boundary. Recent theoretical models suggest that certain bulk insulators with large spin orbit interactions may also naturally support conducting topological boundary states in the quantum limit, which opens up the possibility for studying unusual quantum Hall like phenomena in zero external magnetic fields. Bulk Bi1 xSbx single crystals are predicted to be prime candidates for one such unusual Hall phase of matter known as the topological insulator. The hallmark of a topological insulator is the existence of metallic surface states that are higher dimensional analogues of the edge states that characterize a quantum spin Hall insulator. In addition to its interesting boundary states, the bulk of Bi1 xSbx is predicted to exhibit three dimensional Dirac particles, another topic of heightened current interest following the new findings in two dimensional graphene and charge quantum Hall fractionalization observed in pure bismuth. However, despite numerous transport and magnetic measurements on the Bi1 xSbx family since the 1960s, no direct evidence of either topological Hall states or bulk Dirac particles has been found. Here, using incident photon energy modulated angle resolved photoemission spectroscopy (IPEM ARPES) we report the direct observation of massive Dirac particles in the bulk of Bi0.9Sb0.1, locate the Kramers points at the sample's boundary and provide a comprehensive mapping of the Dirac insulator's gapless surface electron bands. These findings taken together suggest that the observed surface state on the boundary of the bulk insulator is a realization of the 'topological metal' They also suggest that this material has potential application in developing next generation quantum computing devices that may incorporate 'light like' bulk carriers and spin textured surface currents.", "author_names": [ "D Hsieh", "Dong Qian", "L Andrew Wray", "Y Y Xia", "Yew San Hor", "Robert J Cava", "M Zahid Hasan" ], "corpus_id": 4402113, "doc_id": "4402113", "n_citations": 2102, "n_key_citations": 26, "score": 0, "title": "A topological Dirac insulator in a quantum spin Hall phase", "venue": "Nature", "year": 2008 }, { "abstract": "Topological insulators are new states of quantum matter in which surface states residing in the bulk insulating gap of such systems are protected by time reversal symmetry. The study of such states was originally inspired by the robustness to scattering of conducting edge states in quantum Hall systems. Recently, such analogies have resulted in the discovery of topologically protected states in two dimensional and three dimensional band insulators with large spin orbit coupling. So far, the only known three dimensional topological insulator is BixSb1 x, which is an alloy with complex surface states. Here, we present the results of first principles electronic structure calculations of the layered, stoichiometric crystals Sb2Te3, Sb2Se3, Bi2Te3 and Bi2Se3. Our calculations predict that Sb2Te3, Bi2Te3 and Bi2Se3 are topological insulators, whereas Sb2Se3 is not. These topological insulators have robust and simple surface states consisting of a single Dirac cone at the G point. In addition, we predict that Bi2Se3 has a topologically non trivial energy gap of 0.3 eV, which is larger than the energy scale of room temperature. We further present a simple and unified continuum model that captures the salient topological features of this class of materials. First principles calculations predict that Bi2Se3, Bi2Te3 and Sb2Te3 are topological insulators three dimensional semiconductors with unusual surface states generated by spin orbit coupling whose surface states are described by a single gapless Dirac cone. The calculations further predict that Bi2Se3 has a non trivial energy gap larger than the energy scale kBT at room temperature.", "author_names": [ "Haijun Zhang", "Chaoxing Liu", "Xiao-liang Qi", "Xi Dai", "Zhong Fang", "Shou-Cheng Zhang" ], "corpus_id": 120176337, "doc_id": "120176337", "n_citations": 3566, "n_key_citations": 74, "score": 0, "title": "Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface", "venue": "", "year": 2009 }, { "abstract": "Recent experiments and theories have suggested that strong spin orbit coupling effects in certain band insulators can give rise to a new phase of quantum matter, the so called topological insulator, which can show macroscopic quantum entanglement effects. Such systems feature two dimensional surface states whose electrodynamic properties are described not by the conventional Maxwell equations but rather by an attached axion field, originally proposed to describe interacting quarks. It has been proposed that a topological insulator with a single Dirac cone interfaced with a superconductor can form the most elementary unit for performing fault tolerant quantum computation. Here we present an angle resolved photoemission spectroscopy study that reveals the first observation of such a topological state of matter featuring a single surface Dirac cone realized in the naturally occurring Bi_2Se_3 class of materials. Our results, supported by our theoretical calculations, demonstrate that undoped Bi_2Se_3 can serve as the parent matrix compound for the long sought topological device where in plane carrier transport would have a purely quantum topological origin. Our study further suggests that the undoped compound reached via n to p doping should show topological transport phenomena even at room temperature.", "author_names": [ "Yuqi Xia", "Dong Qian", "D Hsieh", "L Andrew Wray", "Arijeet Pal", "Hsin Lin", "Arun Bansil", "D Grauer", "Yew San Hor", "Robert J Cava", "M Zahid Hasan" ], "corpus_id": 118305489, "doc_id": "118305489", "n_citations": 1946, "n_key_citations": 41, "score": 0, "title": "Observation of a large gap topological insulator class with a single Dirac cone on the surface", "venue": "", "year": 2009 }, { "abstract": "The recent discovery of topological insulators has revived interest in the band topology of insulators. In this Letter, we extend the topological classification of band structures to include certain crystal point group symmetry. We find a class of three dimensional \"topological crystalline insulators\" which have metallic surface states with quadratic band degeneracy on high symmetry crystal surfaces. These topological crystalline insulators are the counterpart of topological insulators in materials without spin orbit coupling. Their band structures are characterized by new topological invariants. We hope this work will enlarge the family of topological phases in band insulators and stimulate the search for them in real materials.", "author_names": [ "Liang Fu" ], "corpus_id": 14426263, "doc_id": "14426263", "n_citations": 1012, "n_key_citations": 21, "score": 0, "title": "Topological crystalline insulators.", "venue": "Physical review letters", "year": 2011 }, { "abstract": "Certain insulators have exotic metallic states on their surfaces. These states are formed by topological effects that also render the electrons travelling on such surfaces insensitive to scattering by impurities. Such topological insulators may provide new routes to generating novel phases and particles, possibly finding uses in technological applications in spintronics and quantum computing.", "author_names": [ "Joel E Moore" ], "corpus_id": 1911343, "doc_id": "1911343", "n_citations": 1799, "n_key_citations": 11, "score": 0, "title": "The birth of topological insulators", "venue": "Nature", "year": 2010 } ]

[ { "abstract": "Abstract We report on a three waveguide electro optic switch for compact photonic integrated circuits and data routing applications. The device features a plasmonic metal oxide semiconductor (MOS) mode for enhanced light matter interactions. The switching mechanism originates from a capacitor like design where the refractive index of the active medium, indium tin oxide, is altered via shifting the plasma frequency due to carrier accumulation inside the waveguide based MOS structure. This light manipulation mechanism controls the transmission direction of transverse magnetic polarized light into either a CROSS or BAR waveguide port. The extinction ratio of 18 (7) dB for the CROSS (BAR) state, respectively, is achieved via a gating voltage bias. The ultrafast broadband fJ/bit device allows for seamless integration with silicon on insulator platforms for low cost manufacturing.", "author_names": [ "Chenran Ye", "Kunyan Liu", "Richard A Soref", "Volker J Sorger" ], "corpus_id": 15691481, "doc_id": "15691481", "n_citations": 57, "n_key_citations": 4, "score": 1, "title": "A compact plasmonic MOS based 2x2 electro optic switch", "venue": "", "year": 2015 }, { "abstract": "Plasmonic structures can be constructed from precise numbers of well defined metal nanoparticles that are held together with molecular linkers, templates or spacers. Such structures could be used to concentrate, guide and switch light on the nanoscale in sensors and various other devices. DNA was first used to rationally design plasmonic structures in 1996, and more sophisticated motifs have since emerged as effective and versatile species for guiding the assembly of plasmonic nanoparticles into structures with useful properties. Here we review the design principles for plasmonic nanostructures, and discuss how DNA has been applied to build finite number assemblies (plasmonic molecules) regularly spaced nanoparticle chains (plasmonic polymers) and extended two and three dimensional ordered arrays (plasmonic crystals)", "author_names": [ "Shawn J Tan", "Michael J Campolongo", "Dan Luo", "Wenlong Cheng" ], "corpus_id": 18743936, "doc_id": "18743936", "n_citations": 669, "n_key_citations": 4, "score": 0, "title": "Building plasmonic nanostructures with DNA.", "venue": "Nature nanotechnology", "year": 2011 }, { "abstract": "Plasmonic clusters can support Fano resonances, where the line shape characteristics are controlled by cluster geometry. Here we show that clusters with a hemicircular central disk surrounded by a circular ring of closely spaced, coupled nanodisks yield Fano like and non Fano like spectra for orthogonal incident polarization orientations. When this structure is incorporated into an uniquely broadband, liquid crystal device geometry, the entire Fano resonance spectrum can be switched on and off in a voltage dependent manner. A reversible transition between the Fano like and non Fano like spectra is induced by relatively low ~6 V) applied voltages, resulting in a complete on/off switching of the transparency window.", "author_names": [ "Wei-Shun Chang", "Joseph B Lassiter", "Pattanawit Swanglap", "Heidar Sobhani", "Saumyakanti Khatua", "Peter J Nordlander", "Naomi J Halas", "Stephan Link" ], "corpus_id": 207719250, "doc_id": "207719250", "n_citations": 295, "n_key_citations": 3, "score": 1, "title": "A plasmonic Fano switch.", "venue": "Nano letters", "year": 2012 }, { "abstract": "The concept, analysis, and design of series switches for graphene strip plasmonic waveguides at near infrared frequencies are presented. Switching is achieved by using graphene's field effect to selectively enable or forbid propagation on a section of the graphene strip waveguide, thereby allowing good transmission or high isolation, respectively. The electromagnetic modeling of the proposed structure is performed using full wave simulations and a transmission line model combined with a matrix transfer approach, which takes into account the characteristics of the plasmons supported by the different graphene strip waveguide sections of the device. The performance of the switch is evaluated versus different parameters of the structure, including surrounding dielectric media, electrostatic gating and waveguide dimensions.", "author_names": [ "Juan Sebastian Gomez-Diaz", "Julien Perruisseau-Carrier" ], "corpus_id": 870271, "doc_id": "870271", "n_citations": 236, "n_key_citations": 4, "score": 1, "title": "Graphene based plasmonic switches at near infrared frequencies.", "venue": "Optics express", "year": 2013 }, { "abstract": "We demonstrate a surface plasmon polariton (SPP) waveguide all optical switch that combines the unique physical properties of small molecules and metallic (plasmonic) nanostructures. The switch consists of a pair of gratings defined in an aluminum film coated with a 65 nm thick layer of photochromic (PC) molecules. The first grating couples a signal beam consisting of free space photons to SPPs that interact effectively with the PC molecules. These molecules can reversibly be switched between transparent and absorbing states using a free space optical pump. In the transparent (signal \"on\" state, the SPPs freely propagate through the molecular layer, and in the absorbing (signal \"off\" state, the SPPs are strongly attenuated. The second grating serves to decouple the SPPs back into a free space optical beam, enabling measurement of the modulated signal with a far field detector. In a preliminary study, the switching behavior of the PC molecules themselves was confirmed and quantified by surface plasmon resonance spectroscopy. The excellent (16% overlap of the SPP mode profile with the thin layer of switching molecules enabled efficient switching with power densities of approximately 6.0 mW/cm2 in 1.5 microm x 8 microm devices, resulting in plasmonic switching powers of 0.72 nW per device. Calculations further showed that modulation depths in access of 20 dB can easily be attained in optimized designs. The quantitative experimental and theoretical analysis of the nonvolatile switching behavior in this letter guides the design of future nanoscale optically or electrically pumped optical switches.", "author_names": [ "Ragip A Pala", "Ken T Shimizu", "Nicholas A Melosh", "Mark L Brongersma" ], "corpus_id": 22951975, "doc_id": "22951975", "n_citations": 205, "n_key_citations": 2, "score": 1, "title": "A nonvolatile plasmonic switch employing photochromic molecules.", "venue": "Nano letters", "year": 2008 }, { "abstract": "Active plasmonic band stop filters based on single and double layer doped graphene metamaterials at the THz wavelengths are proposed and investigated numerically by using the finite difference time domain (FDTD) method. The metamaterial unit cell structure is composed of two parallel graphene nanoscale ribbons. Simulated results exhibit that significant resonance wavelength shifts can be achieved with a slight variation of the doping concentration of the graphene ribbons. Besides, the asymmetry double layer graphene metamaterial device has two apparent filter dips while the symmetry single double layer and asymmetry single layer graphene metamaterial devices just only one. The metamaterials with symmetry single layer and asymmetry double layer graphene can be used as a high sensitivity refractive sensor with the sensitivity up to 5100 nm/RIU and a two circuit switch, respectively. These prospects pave the way towards ultrafast active graphene based plasmonic devices for THz applications.", "author_names": [ "Zhongchao Wei", "Xianping Li", "Jianjun Yin", "Rong Huang", "Yuebo Liu", "Wei Wang", "Hongzhan Liu", "Hongyun Meng", "Ruisheng Liang" ], "corpus_id": 33332946, "doc_id": "33332946", "n_citations": 45, "n_key_citations": 2, "score": 1, "title": "Active plasmonic band stop filters based on graphene metamaterial at THz wavelengths.", "venue": "Optics express", "year": 2016 }, { "abstract": "The atom sets an ultimate scaling limit to Moore's law in the electronics industry. While electronics research already explores atomic scales devices, photonics research still deals with devices at the micrometer scale. Here we demonstrate that photonic scaling, similar to electronics, is only limited by the atom. More precisely, we introduce an electrically controlled plasmonic switch operating at the atomic scale. The switch allows for fast and reproducible switching by means of the relocation of an individual or, at most, a few atoms in a plasmonic cavity. Depending on the location of the atom either of two distinct plasmonic cavity resonance states are supported. Experimental results show reversible digital optical switching with an extinction ratio of 9.2 dB and operation at room temperature up to MHz with femtojoule (fJ) power consumption for a single switch operation. This demonstration of an integrated quantum device allowing to control photons at the atomic level opens intriguing perspectives for a fully integrated and highly scalable chip platform, a platform where optics, electronics, and memory may be controlled at the single atom level.", "author_names": [ "Alexandros Emboras", "Jens Niegemann", "Ping Ma", "Christian Haffner", "Andreas Pedersen", "Mathieu Luisier", "Christian Hafner", "Th Schimmel", "Juerg Leuthold" ], "corpus_id": 35904498, "doc_id": "35904498", "n_citations": 76, "n_key_citations": 3, "score": 1, "title": "Atomic Scale Plasmonic Switch.", "venue": "Nano letters", "year": 2016 }, { "abstract": "We present a nano scale electro plasmonic scheme operating at 1550 nm based on plasmonic Metal Insulator Metal waveguide and stub filter configuration. The linear dependency of the transmission spectra of the stub filter to the length of the stubs allows designing a switch that works as normally ON or OFF switch by selecting the length of the stubs 300 or 410 nm, respectively. In our proposed waveguide based structure, the core is an electro optic material known as 4 dimethyl amino Nmethyl 4 stilbazolium tosylate with the refractive index 2.2 while the metal cladding is silver. Three dimensional Finite Element Method simulations demonstrated that by applying a 10 V voltage to the silver cladding, a red shift in the transmission spectra of the filter leads to turn the switch OFF or ON with calculated extinction ratio 13.83$ 13.83 and 11.81 dB, respectively. The calculation of the capacitance implies that the switching rise time of the switch is less than 20 fs and the bandwidth is far beyond the 18 GHz. At the maximum dimension $460\\\\hbox {nm}\\times 450\\\\hbox {nm}$460nmx450nm, the subwavelength size of the switch promises the potential for future compact integrated plasmonic circuitry. For the verification of three dimensional simulation results, we have tried it, using two dimensional transmission line method for modeling the stub filter, which demonstrates a reasonable accuracy in comparison with three dimensional finite element method.", "author_names": [ "Ahmad Naseri Taheri", "Hassan Kaatuzian" ], "corpus_id": 123102801, "doc_id": "123102801", "n_citations": 29, "n_key_citations": 1, "score": 1, "title": "Numerical investigation of a nano scale electro plasmonic switch based on metal insulator metal stub filter", "venue": "", "year": 2015 }, { "abstract": "A high performance electro optical cross bar switch based on a vertical graphene plasmonic directional coupler is proposed. The structure consists of two pattern free graphene plasmonic waveguides which have major advantages over their previous counterparts. An ultrashort switching length of just 223 nm is obtained at the frequency of 37.5 THz. To the best of our knowledge, this switching length is remarkably shorter than those in the recently reported structures. Our designed structure is simulated using a three dimensional finite difference time domain method. According to the illustrated results, extinction ratios of 10.5 and 9.52 dB are obtained at the cross and bar ports, respectively, and a wide spectral width of more than 1 mm is presented. The required switching voltage is also calculated as 6 V and a very high 3 dB bandwidth of more than 60 GHz is obtained. An extremely low switching energy of 3.8 fJ/bit is also estimated.", "author_names": [ "Shahram Bahadori-Haghighi", "Rahim Ghayour", "Mohammad Hossein Sheikhi" ], "corpus_id": 20646869, "doc_id": "20646869", "n_citations": 23, "n_key_citations": 1, "score": 1, "title": "Three Dimensional Analysis of an Ultrashort Optical Cross Bar Switch Based on a Graphene Plasmonic Coupler", "venue": "Journal of Lightwave Technology", "year": 2017 }, { "abstract": "Plasmonic memristors are electrically activated optical switches with a memory effect. This effect is important for a new generation of latching optical switches that maintain their state without power consumption. It is also of interest for new optical memories that can be activated by a single electrical write/erase impulse. The operation principle is based on the reversible formation of a conductive path in the dielectric layer of a plasmonic metal insulator metal waveguide. Extinction ratios of 12 dB (6 dB) are demonstrated in 10 mm (5 mm) long devices for operating voltages of 2 V. With this, the devices feature the characteristics of electronic resistive random access memory, but for the field of plasmonics. Such plasmonic memristors are interesting in view of new applications in information storage and for low power circuit switching.", "author_names": [ "Claudia Hoessbacher", "Yuriy Fedoryshyn", "Alexandros Emboras", "Argishti Melikyan", "Manfred Kohl", "David Hillerkuss", "Christian Hafner", "Juerg Leuthold" ], "corpus_id": 56090152, "doc_id": "56090152", "n_citations": 71, "n_key_citations": 2, "score": 1, "title": "The plasmonic memristor: a latching optical switch", "venue": "", "year": 2014 } ]

[ { "abstract": "A new type of semiconductor laser is studied, in which injected carriers in the active region are quantum mechanically confined in two or three dimensions (2D or 3D) Effects of such confinements on the lasing characteristics are analyzed. Most important, the threshold current of such laser is predicted to be far less temperature sensitive than that of conventional lasers, reflecting the reduced dimensionality of electronic state. In the case of 3D QW laser, the temperature dependence is virtually eliminated. An experiment on 2D quantum well lasers is performed by placing a conventional laser in a strong magnetic field (30 T) and has demonstrated the predicted increase of T0 value from 144 to 313 degC.", "author_names": [ "Yasuhiko Arakawa", "Hiroyuki Sakaki" ], "corpus_id": 122995197, "doc_id": "122995197", "n_citations": 2904, "n_key_citations": 33, "score": 1, "title": "Multidimensional quantum well laser and temperature dependence of its threshold current", "venue": "", "year": 1982 }, { "abstract": "By tailoring the active region quantum wells and barriers of 4.5 5.0 mm emitting quantum cascade lasers (QCLs) the device performances dramatically improve. Deep well QCLs significantly suppress carrier leakage, as evidenced by high values for the threshold current characteristic temperature <i>T</i>₀ (253 K) and the slope efficiency characteristic temperature <i>T</i>₁ (285 K) but, due to stronger quantum confinement, the global upper laser level lifetime t_4g decreases, resulting in basically the same room temperature (RT) threshold current density <i>J</i>_th as conventional QCLs. Tapered active region (TA) QCLs, devices for which the active region barrier heights increase in energy from the injection to the exit barriers, lead to recovery of the t_4g value while further suppressing carrier leakage. As a result, experimental RT <i>J</i>_th values from moderate taper TA 4.8 mm emitting QCLs are ~14% less than for conventional QCLs and <i>T</i>₁ reaches values as high as 797 K. A step taper TA (STA) QCL design provides both complete carrier leakage suppression and an increase in the t_4g value, due to Stark effect reduction and strong asymmetry. Then, the RT <i>J</i>_th value decreases by at least 25% compared to conventional QCLs of same geometry. In turn, single facet, RT pulsed and continuous wave maximum wallplug efficiency values of 29% and 27% are projected for 4.6 4.8 mm emitting QCLs.", "author_names": [ "Dan Botez", "Jae Cheol Shin", "J D Kirch", "Chun-Chieh Chang", "Luke J Mawst", "Thomas L Earles" ], "corpus_id": 42910540, "doc_id": "42910540", "n_citations": 36, "n_key_citations": 1, "score": 0, "title": "Multidimensional Conduction Band Engineering for Maximizing the Continuous Wave (CW) Wallplug Efficiencies of Mid Infrared Quantum Cascade Lasers", "venue": "IEEE Journal of Selected Topics in Quantum Electronics", "year": 2013 }, { "abstract": "A method for calculating the electronic states and optical properties of multidimensional semiconductor quantum structures is described. The method is applicable to heterostructures with confinement in any number of dimensions: e.g. bulk, quantum wells, quantum wires and quantum dots. It is applied here to model bulk and multiquantum well (MQW) InGaAsP active layer quaternary lasers. The band parameters of the quaternary system required for the modeling are interpolated from the available literature. We compare bulk versus MQW performance, the effects of compressive and tensile strain, room temperature versus high temperature operation and 1.3 versus 1.55 pm wavelength operation. Our model shows that: compressive strain improves MQW laser performance. MQW lasers have higher amplification per carrier and higher differential gain than bulk lasers, however, MQW performance is far from ideal because of occupation of non lasing minibands. This results in higher carrier densities at threshold than in bulk lasers, and may nullify the advantage of MQW lasers over bulk devices for high temperature operation.", "author_names": [ "David Gershoni", "Charles Howard Henry", "Gene A Baraff" ], "corpus_id": 122181045, "doc_id": "122181045", "n_citations": 161, "n_key_citations": 3, "score": 0, "title": "Calculating the optical properties of multidimensional heterostructures: Application to the modeling of quaternary quantum well lasers", "venue": "", "year": 1993 }, { "abstract": "A robust, modular and comprehensive simulation model, built on a first principles microscopic physics basis, includes the fully time dependent and spatially resolved internal optical, carrier and temperature fields within an arbitrary geometry edge emitting high power semiconductor laser device. The simulator is designed to run interactively on a multi processor shared memory graphical supercomputer by utilizing a highly efficient algorithm running in parallel over multiple CPUs. The experimentally validated semiconductor optical response is computed using a microscopic approach that includes the relevant bandstructure of the Quantum Well and confining barrier regions together with a fully quantum mechanical many body calculation that takes all occupied bands into account. The latter quantity is introduced into the simulator via a multidimensional look up table that captures the local dependence of the gain and refractive index of the structure over a broad range of frequencies and carrier densities. The simulator is designed in a modular form so as to be able to include differing device geometries (broad area, flared, multiple contacts, arrays, filters (DBR or DFB grating sections) index/gain guiding, temperature and current profiles and so on. Results will be presented for both broad area and MOPA devices.", "author_names": [ "Jerome V Moloney", "M Kolesik", "Joerg Hader", "Stephan W Koch" ], "corpus_id": 111152153, "doc_id": "111152153", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Modeling high power semiconductor lasers: from microscopic physics to device applications", "venue": "Advanced High Power Lasers and Applications", "year": 2000 }, { "abstract": "We report room temperature near infrared nanolasers based on AlGaAs/GaAs nanowire/single quantum well heterostructure grown by MOCVD. When subjects to pulsed optical excitation at room temperature, the nanowire exhibits lasing at 791 nm with low threshold of 2.5 kW/cm2.", "author_names": [ "Wei Wei", "Xin Yan", "Xiaofeng Ma", "Vittorio Giarola", "Xia Zhang" ], "corpus_id": 174819441, "doc_id": "174819441", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A room temperature near infrared nanowire/quantum well laser", "venue": "2018 23rd Opto Electronics and Communications Conference (OECC)", "year": 2018 }, { "abstract": "High power GaSb based type I GaInAsSb/AlGaAsSb three quantum wells laser diodes emitting at 2.4 mm were optimized and fabricated. The laser wafer was grown with solid source Molecular Beam Epitaxy System. With optimizations of the epitaxial structure design and the ohmic contact, the operation voltage and the internal loss decreased; the internal quantum efficiency and output power increased. The internal quantum efficiency was determined about 80.1% and the internal loss was 12 cm 1 by measuring laser diodes with different cavity lengths. An uncoated 2 mm long laser diode with 90 mm wide aperture exhibited a threshold current density of 222 A/cm2 (74 A/cm2 per quantum well) a continuous wave output power of 232 mW and a quasi continuous wave (1 kHz, 10 ms) output power of 1 W at room temperature.", "author_names": [ "Yuzhi Song", "Jiakun Song", "Yu Zhang", "Kangwen Li", "Yun Xu", "Guofeng Song", "Lianghui Chen" ], "corpus_id": 110511468, "doc_id": "110511468", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "High power and low loss room temperature operation of 2.4mm GaInAsSb/AlGaAsSb type I strained quantum well laser diodes", "venue": "Applied Optics and Photonics China", "year": 2015 }, { "abstract": "A ridge waveguide 1.55 mm semiconductor laser with a multiple quantum well carrier confinement structure was characterized from room temperature down to 10 K. The temperature dependence of important laser parameters, such as threshold current, series resistance, differential efficiency, and emission wavelength, extracted from standard L I/I V measurements, is reported. The applicability of the standard ideal diode model of semiconductor laser at cryogenic temperatures is analyzed.", "author_names": [ "Emmanuel Mercado", "Dipendra Adhikari", "Gennady A Smolyakov", "Marek Osinski" ], "corpus_id": 51745118, "doc_id": "51745118", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Low temperature characterization of a 1.55 mm multiple quantum well laser down to 10 K", "venue": "Photonics West Optoelectronic Materials and Devices", "year": 2013 }, { "abstract": "It is well known that potential fluctuation in InGaN quantum well layers is very large. To investigate its effect on the laser characteristics, we have found a new method to evaluate the degree of fluctuation from the temperature dependence of the lasing threshold excitation power density.", "author_names": [ "Itta Oshima", "Y Ikeda", "Shigeta Sakai", "Atsushi A Yamaguchi", "Yuya Kanitani", "Shigetaka Tomiya" ], "corpus_id": 53600657, "doc_id": "53600657", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A New Method to Evaluate the Degree of Potential Fluctuation in InGaN Quantum Well Laser Diodes by Optical Pump Stimulated Emission Measurements", "venue": "2018 IEEE International Semiconductor Laser Conference (ISLC)", "year": 2018 }, { "abstract": "We demonstrate room temperature transparency and optically pumped lasing with an InGaAs quantum well active region integrated in an InP nanoresonator cavity grown monolithically on silicon. As grown silicon transparent lasers will enable on chip optical interconnects.", "author_names": [ "Indrasen Bhattacharya", "Fanglu Lu", "Gilliard Nardel Malheiros-Silveira", "Saniya Deshpande", "Kar Wei Ng", "Connie J Chang-Hasnain" ], "corpus_id": 46492410, "doc_id": "46492410", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Room temperature InGaAs/InP quantum well in nanopillar laser directly grown on silicon", "venue": "2016 Conference on Lasers and Electro Optics (CLEO)", "year": 2016 }, { "abstract": "Room temperature continuous wave operation at 540 nm was demonstrated with a BeZnCdSe quantum well laser diode. Threshold current density of the narrow stripe, 800 um cavity laser was as low as ~1.7 kA/cm²", "author_names": [ "S Fujisaki", "Hiroshi Nakajima", "Jun-ichi Kasai", "Ryoichi Akimoto", "Kunihiko Tasai", "Yoshiro Takiguchi", "Takeshi Kikawa", "Tsunenori Asatsuma", "Koshi Tamamura", "S Tanaka", "Shinji Tsuji", "Haruhiko Kuwatsuka", "Toshifumi Hasama", "Hiroshi Ishikawa" ], "corpus_id": 37495984, "doc_id": "37495984", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "540 nm green room temperature CW operation of BeZnCdSe single quantum well laser diode", "venue": "22nd IEEE International Semiconductor Laser Conference", "year": 2010 } ]

[ { "abstract": "Nowadays, the critical dimensions (CD) of semiconductor manufacturing processes are gradually declining, and various materials, reactants, or machine equipment is becoming more and more difficult. Therefore, the green supply chain management (GSCM) of smart high tech factories has also become the target of competition for cutting edge companies, because of this management. The more mature the mechanism of high production speed, lower operating costs and the higher the quality. In addition, corporate social responsibility (CSR) governance has also become an important investment evaluation item for semiconductor factories in recent years. As long as internationally renowned manufacturers start CSR, it is a pity that there are already some manufacturers. The establishment of a supply chain management system also synchronously promotes CSR, but there are few manufacturers that integrate CSR and green supply chain management, let alone the application of an intelligent management platform (IMP) This study builds a GSM platform (GSMP) based on the aforementioned problems, and the cluster analysis of K means is used to optimize the management platform to optimize the overall performance of the management platform. Through the simulation results of this study, it is found that the performance of this management platform is far superior to the current mechanism of using human operation, whether it is the speed of emergency processing or the final management operation performance, which shows that this study industry contribution.", "author_names": [ "Hsiao-Chuan Wang", "Kuo-Chi Chang", "Kai-Chun Chu", "Yuh-Chung Lin", "Tsui-Lien Hsu", "Fu-Hsiang Chang" ], "corpus_id": 227277793, "doc_id": "227277793", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Study of Green Supply Chain Management Platform Performance for Intelligent Hightech Factory Based on Advanced CSR Governance", "venue": "2020 15th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT)", "year": 2020 }, { "abstract": "Nowadays, due to ever decreasing product life cycles and high external pressure to cut costs, the ramp up of production lines must be significantly shortened and simplified. This is only possible if a forecast of the impact of modification within an existing production environment is available, helping during decision making of production methods. This type of predictions will have a direct impact on the cost effective production process, maintaining concerns regarding the environmental and social impacts. These are the ideas behind the project Innovative Reuse of modular knowledge Based devices and technologies for Old, Renewed and New factories (ReBorn) The present paper describes the System Assessment Tool, a software application developed in ReBorn, which is used for assessing the sustainability of highly adaptive production systems through the use of Reliability, Life Cycle Cost and Life Cycle Assessment metrics, in the form of a equipment labeling scheme. This labeling scheme consists on classifying the dependability of industrial equipment, based on the collected metrics. To that intent, several simulation processes were performed, in order to assess the suitability of the labeling system, in comparison to the Quality metric that is highly preferable among the industrial partners. The simulation results show that a two layer equipment labeling system is the most suitable approach to be used for classification. Keywords Smart factories; Equipment label; Life cycle assessment; Re use; Production systems.", "author_names": [ "Susana Aguiar", "Rui Pinto", "Joao C P Reis", "Gil Goncalves" ], "corpus_id": 54555012, "doc_id": "54555012", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A Life cycle Equipment Labeling System for Machine Classification in Smart Factories", "venue": "", "year": 2017 }, { "abstract": "The possibility of having the Internet accessibility everywhere and every time and the progressive reduction of the dimensions of hardware equipment, in addition to the advent of novel ICT paradigms realizing the Internet of Things and Smart City visions, made available the design and realization of an innovative type of applications where data play a key role, promising to achieve a non negligible impact on the society and business processes. The right management, control, and distribution of data are extremely critical process in our society, so that it is always referred as information society. This is boosted by the proliferation of the social networks within our lives, and the upcoming of the Internet of Things within our homes and factories. Having such a vast volume of data to be processed in order to take decisions and/or infer knowledge poses a number of challenges. The issue of properly storing such data leads to the advent of different approaches than the traditional relational databases, such as the NoSQL products. The issue of supporting the scalability of the overall communication infrastructure and to balance the load of the consequent processing cause the shift from proprietary and centralized computing solutions to more distributed and multi tenant approaches, such as the cloud computing and its variants. However, the processing is still centralized in the core of the infrastructures, and we only see a change on how such a core is concretely realized. Decentralizing the processing by distributing in along all the layers of the infrastructure is extremely needed, so as to handle the data scale and also the demand for timely responses. To let this to happen, novel processing approaches and schemes are emerging. We are witnessing an interplay among soft computing and machine learning for big data mining and processing.1 A non marginal aspect is also on how to extract what is hidden in such a large amount of information, which is mostly non structured or suitable for all the possible applications using them. It is extremely important to learn in an unsupervised manner from these data so as to extract the knowledge that they contain. A lot of historical data is currently available and storing all of them will surely reach the storage limits of the system. It is important to infer knowledge and keep only it instead of all the data. Last, policy makers need supports when taking decisions and such data can be of pivotal importance for them. In smart cities and factories certain decisions may be needed to be taken in an automatic manner so as to fast react to certain sudden and potentially critical events. It is extremely crucial understand how artificial intelligence can be used in such contexts and their possible limits. The aim of this special issue was to bring together experiences between soft computing and machine learning to the key issue of data mining to promote a convergence and cross fertilization among them. To this Special Issue, 14 articles, as they present the most interesting research studies within the subject matter of this special issue. The paper \"Personalized content recommendation scheme based on trust in online social networks\" by Jaesoo Yoo et al2 presents a solution for content recommendation leveraging on trust estimations obtained from data extracted by online social network services. The behavior of a given person over the social network and the relationship with other users are collected and used to infer his/her trustworthiness by aggregating its experience and reputations. The proposed approach has been implemented and assessed, showing a reduced error than the main related works within the current literature. The paper \"Deep Learning for EEG Data Analytics: A Survey\" by Jason J. Jung et al3 analyses the current literature semi supervised learning using EEG data analytics and points our pros and cons of these solutions to analyze EEG data. Such a study presents what are the main applications of EEG data analysis and provides concrete examples. The study ends by highlighting the future possible research directions in the context of analyzing EEG data, mainly by leveraging the recent findings deep learning, and possible additional applications. The paper \"Extraction of abstracted sensory data to reduce the execution time of context aware services in wearable computing environments\" by Jongsun Choi et al4 presents a reducing method for the execution time of context aware services. The proposed method gives a better performance without searching every single keyword element among the triplet sets. Also, they suggested method to the context aware workflow middleware and demonstrated that the proposed method improves the processing time by at least 30% compared with the linear search by enhancing the comparison module in the middleware. The paper \"Opcode sequence analysis of Android malware by a convolutional neural network\" by Wenbo Shi et al5 discusses a new malware detection system for mobile devices running the Android Operative System. The proposed scheme uses an optimized deep convolutional neural network to infer knowledge from opcode sequences. The learning solution has been used in a supervised manner by training it multiple times using as input the raw opcode sequences obtained from a selected decompiled known Android malware. This allows to have a proper learning of the", "author_names": [ "Chang Choi", "Florin Pop", "Jun Huang" ], "corpus_id": 221356221, "doc_id": "221356221", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Novel data mining paradigms based on soft computing and machine learning in the current and upcoming information society revolution", "venue": "Concurr. Comput. Pract. Exp.", "year": 2020 }, { "abstract": "Machine learning (ML) is nowadays embedded in several computing devices, consumer electronics, and cyber physical systems. Smart sensors are deployed everywhere, in applications such as wearables and perceptual computing devices, and intelligent algorithms power our connected world. These devices collect and aggregate volumes of data, and in doing so, they augment our society in multiple ways; from healthcare, to social networks, to consumer electronics, and many more. To process these immense volumes of data, ML is emerging as the de facto analysis tool that powers several aspects of our Big Data society. Applications spanning from infrastructure (smart cities, intelligent transportation systems, smart grids, and to name a few) to social networks and content delivery, to e commerce and smart factories, and emerging concepts such as self driving cars and autonomous robots, are powered by ML technologies. These emerging systems require real time inference and decision support; such scenarios, therefore, may use customized hardware accelerators, are typically bound by limited resources, and are restricted to limited connectivity and bandwidth. Thus, near sensor computation and near sensor intelligence have started emerging as necessities to continue supporting the paradigm shift of our connected world. The need for real time intelligent data analytics (especially in the era of Big Data) for decision support near the data acquisition points emphasizes the need for revolutionizing the way we design, build, test, and verify processors, accelerators, and systems that facilitate ML (and deep learning, in particular) implemented in resource constrained environments for use at the edge and the fog. As such, traditional von Neumann architectures are no longer sufficient and suitable, primarily because of limitations in both performance and energy efficiency caused especially by large amounts of data movement. Furthermore, due to the connected nature of such systems, security and reliability are also critically important. Robustness, therefore, in the form of reliability and operational capability in the presence of faults, whether malicious or accidental, is a critical need for such systems. Moreover, the operating nature of these systems relies on input data that is characterized by the four \"V's\" velocity (speed of data generation) variability (variable forms and types) veracity (unreliable and unpredictable) and volume (i.e. large amounts of data) Thus, the robustness of such systems needs to consider this issue as well. Furthermore, robustness in terms of security, and in terms of reliability to hardware and software faults, in particular, besides their importance when it comes to safety critical applications, is also a positive factor in building trustworthiness toward these disrupting technologies from our society. To achieve this envisioned robustness, we need to refocus on problems such as design, verification, architecture, scheduling and allocation policies, optimization, and many more, for determining the most efficient, secure, and reliable way of implementing these novel applications within a robust, resource constrained system, which may or may not be connected. This special issue, therefore, addresses a key aspect of fog and edge based ML algorithms; robustness (as defined above) under resource constraint scenarios. The special issue presents emerging works in how we design robust systems, both in terms of reliability as well as fault tolerance and security, while operating with a limited number of resources, and possibly in the presence of harsh environments that may eliminate connectivity and pollute the input data.", "author_names": [ "Theocharis Theocharides", "Muhammad Akmal Shafique", "Jungwook Choi", "Onur Mutlu" ], "corpus_id": 218624096, "doc_id": "218624096", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Guest Editorial: Robust Resource Constrained Systems for Machine Learning", "venue": "IEEE Des. Test", "year": 2020 }, { "abstract": "Abstract The factories of the future will make use of actuators, sensors and cyber physical systems (CPS) to provide an environment in which human beings, machines, and resources will communicate as in a social network. In such a network, communication between various \"objects\" relay the current state of the physical world. Business decisions are made using the information and it is therefore critical that this information is accurate and in real time. Information flow is a key enabler of such future factories. Industrial engineers, as designers and improvement agents of such factories of the future, will need to develop better skills in various aspects of data analytics and information communication technologies. This paper describes the development and implementation of a low cost RFID track and trace system (by students) for application in a Learning Factory for teaching undergraduate industrial engineering students key concepts related to Industry 4.0 and \"smart factories\" The benefit of this system is not only a demonstrator to be used in the Learning Factory, but also can be used to teach students in a \"learning by doing\" fashion critical skills related to real time tracking in a manufacturing environment. The system also demonstrates potential low cost implementation of such technologies in SME's.", "author_names": [ "Louis Louw", "Mark Walker" ], "corpus_id": 117218498, "doc_id": "117218498", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Design and implementation of a low cost RFID track and trace system in a learning factory", "venue": "", "year": 2018 }, { "abstract": "The services and applications of the internet of things (IoT) support various areas such as smart home, smart car, smart factory and so on. Previously, different platforms were used for each application and service. Recently, several groups of companies have been trying to integrate and standardise the IoT platforms and two major platforms among them are oneM2M and the Open Interconnect Consortium (OIC) oneM2M and OIC standards enable connected devices to communicate each other regardless of their manufacturers and operating systems. Also, there are attempts to interwork two open platforms. However, security interoperability has been less focused in the interworking. In this paper, we present the comparison of security related methods between oneM2M and OIC standard specifications for the security interoperability. We compare the basic concepts and terminology of two standards by clarifying the same spelled basic terms with different meanings and different terms having similar concepts. Moreover, we analyse security related methods in OIC and oneM2M in a comparative manner. By comparative analysis, we help users understand the interworking and interoperability between oneM2M and OIC standard specifications.", "author_names": [ "Dong In Kim", "Hyun-Gu Lee", "Alavalapati Goutham Reddy", "Jaehwan John Lee", "Ji Sun Shin" ], "corpus_id": 201873671, "doc_id": "201873671", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Comparison of security related methods in Open Interconnect Consortium and one machine to machine for security interoperability", "venue": "", "year": 2019 }, { "abstract": "The production processes of dry method and wet method for producing machine made sand are introduced. The feasibility of machine made sand as a kind of mixture to produce the pile concrete are tested and studied, and the mix proportion of the concrete is optimized. In addition, combining with the factory production status, the application situation of machine made sand in the PHC pile engineering are discussed, and it points out that the using the machine made sand to produce PHC piles has good economic and social benefits.", "author_names": [ "Xu Jian-zha" ], "corpus_id": 112235918, "doc_id": "112235918", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Quality Discussion of Machine made Sand and Its Application for PHC Piles", "venue": "", "year": 2014 }, { "abstract": "Since the 1970's, we have been developing technologies in industrial machine vision including intelligent character recognition to produce automated machines for factories, banks, and post offices. In my talk, I will first introduce a brief history of the industrial machine vision and the intelligent character recognition technologies in applied fields. Then I will discuss the strategies and developments in the fields. I will end my talk by touching on my personal experience as a researcher. As time has passed, our major research objective has changed from factory automation to office automation and from office automation to social/security automation. Consequently, the demand for machines that are capable of dealing with more complex and difficult automation tasks has grown. To meet these demands, a machine often requires multiple recognition procedures. This normally leads to the final recognition rate worsening as the number of procedures increases. Therefore, we propose a multiple hypothesis strategy and an information integration strategy to improve the final recognition rate so that it can meet the machine's specification. Then, it will be shown that the rejection ability of the recognition procedures has an important role in using these strategies effectively. The usefulness of these strategies has been proved through the successful development of mail sorting machines, document readers, and intelligent automated teller machines. Those developments are also described in detail in my talk. Finally, I would like to touch on my experiences as an industrial researcher, which can be summed up by the phrases \"practicality first, novelty second,\" \"development first, research second,\" and \"non vision first, vision second.\"", "author_names": [ "Hiroshi Sako" ], "corpus_id": 12167694, "doc_id": "12167694", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Recognition Strategies in Machine Vision Applications", "venue": "International Machine Vision and Image Processing Conference (IMVIP 2007)", "year": 2007 }, { "abstract": "With increasing automation, the work in manufacturing industry is getting knowledge intensive: workers need to solve complex problems to keep systems running. The knowledge needed in these situations often cannot be found in ready made manuals but it is tacit knowledge possessed by co workers. This paper presents a user study of a knowledge sharing platform. The platform integrates production information and social media features, thus connecting discussions to specific machine states or error situations. The platform was evaluated with factory workers in a workshop. The results show that integration of production information and social media features such as messaging is valuable, as it proactively provides practical solutions to the problem at hand. The results also show that the use of social media features in industrial environment requires changes in organizational policies, processes and culture. The findings of this study can be considered when developing social media applications for industrial use.", "author_names": [ "Susanna Aromaa", "Maria Tsourma", "Stylianos Zikos", "Eija Kaasinen", "Mariia Kreposna", "Anastasios Drosou", "Dimitrios Tzovaras" ], "corpus_id": 199589850, "doc_id": "199589850", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "User Experience of a Social Media Based Knowledge Sharing System in Industry Work", "venue": "IHIET", "year": 2019 }, { "abstract": "Factories of the Future will be distinguished by intelligent machines, automation, human factors integration and knowledge management. Modelling and simulation is recognised as a key enabling technology essential to economic, social and environmental sustainability of future manufacturing systems. This talk will explore the history, recent achievements and directions in modelling and simulation for 21st century factories and supply chains. A systems science approach is employed, from stakeholder engagement through participative modelling to self tuning and self assembling simulations. Our contributions lower the cost of the application of modelling and simulation to manufacturing processes, enabling real time planning, dynamic risk analysis, dashboards and 3D visualisation. This realisation of the virtual factory integrates human factors and decisions into the core technology platform. The implications to future manufacturing enterprises are explored through a series of case studies from aerospace, mining and small and medium manufacturing enterprises.", "author_names": [ "Saeid Nahavandi" ], "corpus_id": 112987803, "doc_id": "112987803", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Factories of the future a system of systems engineering perspective", "venue": "", "year": 2013 } ]

[ { "abstract": "imperfections and impurities in semiconductor silicon is available in our digital library an online access to it is set as public so you can get it instantly. Our book servers saves in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the imperfections and impurities in semiconductor silicon is universally compatible with any devices to read.", "author_names": [ "Kathrin Abendroth" ], "corpus_id": 138302941, "doc_id": "138302941", "n_citations": 9, "n_key_citations": 1, "score": 1, "title": "Imperfections And Impurities In Semiconductor Silicon", "venue": "", "year": 2016 }, { "abstract": "The silicon metal oxide semiconductor (MOS) material system is a technologically important implementation of spin based quantum information processing. However, the MOS interface is imperfect leading to concerns about 1/f trap noise and variability in the electron g factor due to spin orbit (SO) effects. Here we advantageously use interface SO coupling for a critical control axis in a double quantum dot singlet triplet qubit. The magnetic field orientation dependence of the g factors is consistent with Rashba and Dresselhaus interface SO contributions. The resulting all electrical, two axis control is also used to probe the MOS interface noise. The measured inhomogeneous dephasing time, $T_{\\mathrm{2m} \\star$$T2m, of 1.6 ms is consistent with 99.95% 28Si enrichment. Furthermore, when tuned to be sensitive to exchange fluctuations, a quasi static charge noise detuning variance of 2 meV is observed, competitive with low noise reports in other semiconductor qubits. This work, therefore, demonstrates that the MOS interface inherently provides properties for two axis qubit control, while not increasing noise relative to other material choices.As the performance of silicon based qubits has improved, there has been increasing focus on developing designs that are compatible with industrial processes. Here, Jock et al. exploit spin orbit coupling to demonstrate full, all electrical control of a metal oxide semiconductor electron spin qubit.", "author_names": [ "Ryan M Jock", "Noah Tobias Jacobson", "Patrick Harvey-Collard", "Andrew M Mounce", "Vanita Srinivasa", "Daniel R Ward", "John M Anderson", "Ronald P Manginell", "Joel R Wendt", "Martin Rudolph", "Tammy C Pluym", "John King Gamble", "Andrew D Baczewski", "Wayne M Witzel", "Malcolm S Carroll" ], "corpus_id": 19126023, "doc_id": "19126023", "n_citations": 59, "n_key_citations": 3, "score": 1, "title": "A silicon metal oxide semiconductor electron spin orbit qubit", "venue": "Nature Communications", "year": 2018 }, { "abstract": "Heterogeneous integration of III V compound semiconductors on Silicon on Insulator is one the key technology for next generation on chip optical interconnects. In this context, the use of photonic crystals lasers represents a disruptive solution in terms of footprint, activation energy and ultrafast response. In this work, we propose and fabricate very compact laser sources integrated with a passive silicon waveguide circuitry. Using a subjacent Silicon On Insulator waveguide, the emitted light from a photonic crystal based cavity laser is efficiently captured. We study experimentally the evanescent wave coupling responsible for the funneling of the emitted light into the silicon waveguide mode as a function of the hybrid structure parameters, showing that 90% of coupling efficiency is possible.", "author_names": [ "Yacine Halioua", "Alexandre Bazin", "Paul Monnier", "T J Karle", "Gunther Roelkens", "Isabelle Sagnes", "Rama Raj", "Fabrice Raineri" ], "corpus_id": 207318299, "doc_id": "207318299", "n_citations": 92, "n_key_citations": 4, "score": 0, "title": "Hybrid III V semiconductor/silicon nanolaser.", "venue": "Optics express", "year": 2011 }, { "abstract": "We report high output power and high gain semiconductor optical amplifiers integrated on a heterogeneous silicon/III V photonics platform. The devices produce 25 dB of unsaturated gain for the highest gain design, and 14 dBm of saturated output power for the highest output power design. The amplifier structure is also suitable for lasers, and can be readily integrated with a multitude of silicon photonic circuit components. These devices are useful for a wide range of photonic integrated circuits. We show a design method for optimizing the amplifier for the desired characteristics. The amplifier incorporates a low loss and low reflection transition between the heterogeneous active region and a silicon waveguide, and we report transition loss below 1 dB across the entire measurement range and parasitic reflection coefficient from the transition below 1 10 3.", "author_names": [ "Michael L Davenport", "Sandra Skendzic", "Nicolas Volet", "Jared Hulme", "Martijn J R Heck", "John E Bowers" ], "corpus_id": 6058547, "doc_id": "6058547", "n_citations": 66, "n_key_citations": 5, "score": 0, "title": "Heterogeneous Silicon/III V Semiconductor Optical Amplifiers", "venue": "IEEE Journal of Selected Topics in Quantum Electronics", "year": 2016 }, { "abstract": "A method employing conjugated polymer thin film blends is shown to provide a simple and convenient way of greatly enhancing the ultraviolet response of silicon photodetectors. Hybrid organic semiconductor/silicon photodetectors are demonstrated using fluorene copolymers and give a quantum efficiency of 60% at 200 nm. The quantum efficiency is greater than 34% over the entire 200 620 nm range. These devices show promise for use in high sensitivity, low cost UV visible photodetection and imaging applications.", "author_names": [ "Jack W Levell", "Mario Ettore Giardini", "Ifor D W Samuel" ], "corpus_id": 34636736, "doc_id": "34636736", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "A hybrid organic semiconductor/silicon photodiode for efficient ultraviolet photodetection.", "venue": "Optics express", "year": 2010 }, { "abstract": "We have found that a shuffle set dislocation is nucleated in a semiconductor silicon device subjected to severe thermal processing. The dislocation transforms into a dissociated glide set dislocation after annealing at 500degC. A possible mechanism for the nucleation of a perfect shuffle set dislocation during thermal processing is that the dislocation nucleus was nucleated at a low temperature during prior ion implantation processing.", "author_names": [ "Satoshi Izumi", "Hiroyuki Ohta", "Chisato Takahashi", "Hiroyasu Saka" ], "corpus_id": 135569671, "doc_id": "135569671", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Shuffle set dislocation nucleation in semiconductor silicon device", "venue": "", "year": 2010 }, { "abstract": "A sustainable energy future requires power electronics that can enable significantly higher efficiencies in the generation, distribution, and usage of electrical energy. Silicon carbide (4H SiC) is one of the most technologically advanced wide bandgap semiconductor that can outperform conventional silicon in terms of power handling, maximum operating temperature, and power conversion efficiency in power modules. While SiC Schottky diode is a mature technology, SiC power Metal Oxide Semiconductor Field Effect Transistors are relatively novel and there is large room for performance improvement. Specifically, major initiatives are under way to improve the inversion channel mobility and gate oxide stability in order to further reduce the on resistance and enhance the gate reliability. Both problems relate to the defects near the SiO2/SiC interface, which have been the focus of intensive studies for more than a decade. Here we review research on the SiC MOS physics and technology, including its brief history, the state of art, and the latest progress in this field. We focus on the two main scientific problems, namely, low channel mobility and bias temperature instability. The possible mechanisms behind these issues are discussed at the device physics level as well as the atomic scale, with the support of published physical analysis and theoretical studies results. Some of the most exciting recent progress in interface engineering for improving the channel mobility and fundamental understanding of channel transport is reviewed.", "author_names": [ "Gang Liu", "Blair R Tuttle", "Sarit Dhar" ], "corpus_id": 106897932, "doc_id": "106897932", "n_citations": 164, "n_key_citations": 3, "score": 0, "title": "Silicon carbide: A unique platform for metal oxide semiconductor physics", "venue": "", "year": 2015 }, { "abstract": "The epitaxial integration of III V optoelectronic devices on silicon will be the enabling technology for full scale deployment of silicon photonics and the key to improving communication systems. Silicon photonics also offer new opportunities for the realization of ultracompact and fully integrated sensing systems operating in the mid infrared (MIR) regime of the spectrum. In this article, we review recent developments, through several approaches, in the direct metamorphic epitaxial growth of various III V materials based lasers on silicon substrates. We show that GaAs based 1.3 mm III V quantum dot lasers and GaSb based MIR quantum well lasers grown on silicon substrates can operate with low threshold current density and high operating temperature, which hold promise for the future.", "author_names": [ "Eric Tournie", "Laurent Cerutti", "Jean-Baptiste Rodriguez", "Huiyun Liu", "Jiang Wu", "Siming Chen" ], "corpus_id": 138267046, "doc_id": "138267046", "n_citations": 37, "n_key_citations": 0, "score": 0, "title": "Metamorphic III V semiconductor lasers grown on silicon", "venue": "", "year": 2016 }, { "abstract": "The invention discloses a semiconductor silicon wafer manufacture process which comprises the steps of: 1, carrying out double side rough polishing on the silicon wafer after grinding and corroding, wherein the removal amount is 5 100 micrometers; 2, after double side rough polishing, carrying out double side medium polishing, wherein the hardness of polishing cloth or the grain size of grains of a polishing solution is less than that of the rough polishing, and the polishing removal amount is 1 100 micrometers; and 3, directly carrying out single face final polishing on the silicon wafer subjected to the double sidepolishing, wherein the polishing removal amount is less than 0.5 micrometer. The silicon wafer with high planeness can be obtained by the process, and the once yield of the product is improved. The invention has the advantage of providing a manufacture method of the large size silicon wafer for improving the geometric parameter level of the silicon wafer surface.", "author_names": [ "" ], "corpus_id": 141301336, "doc_id": "141301336", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Semiconductor silicon wafer manufacture process", "venue": "", "year": 2009 }, { "abstract": "Metal semiconductor metal (MSM) photodetectors based on graphene/p type Si Schottky junctions are fabricated and characterized. Thermionic emission dominates the transport across the junctions above 260 K with a zero bias barrier height of 0.48 eV. The reverse bias dependence of the barrier height is found to result mostly from the Fermi level shift in graphene. MSM photodetectors exhibit a responsivity of 0.11 A/W and a normalized photocurrent to dark current ratio of 4.55 x 104 mW 1, which are larger than those previously obtained for similar detectors based on carbon nanotubes. These results are important for the integration of transparent, conductive graphene electrodes into existing silicon technologies.", "author_names": [ "Yanbin An", "Ashkan Behnam", "Eric Pop", "Ant Ural" ], "corpus_id": 32536426, "doc_id": "32536426", "n_citations": 172, "n_key_citations": 5, "score": 0, "title": "Metal semiconductor metal photodetectors based on graphene/p type silicon Schottky junctions", "venue": "", "year": 2013 } ]

[ { "abstract": "Ferroelectric tunnel junctions, in which ferroelectric polarization and quantum tunneling are closely coupled to induce the tunneling electroresistance (TER) effect, have attracted considerable interest due to their potential in non volatile and low power consumption memory devices. The ferroelectric size effect, however, has hindered ferroelectric tunnel junctions from exhibiting robust TER effect. Here, our study proposes doping engineering in a two dimensional in plane ferroelectric semiconductor as an effective strategy to design a two dimensional ferroelectric tunnel junction composed of homostructural $p$ type semiconductor/ferroelectric/$n$ type semiconductor. Since the in plane polarization persists in the monolayer ferroelectric barrier, the vertical thickness of two dimensional ferroelectric tunnel junction can be as thin as monolayer. We show that the monolayer In:SnSe/SnSe/Sb:SnSe junction provides an embodiment of this strategy. Combining density functional theory calculations with non equilibrium Green's function formalism, we investigate the electron transport properties of In:SnSe/SnSe/Sb:SnSe and reveal a giant TER effect of 1460$ The dynamical modulation of both barrier width and barrier height during the ferroelectric switching are responsible for this giant TER effect. These findings provide an important insight towards the understanding of the quantum behaviors of electrons in materials at the two dimensional limit, and enable new possibilities for next generation non volatile memory devices based on flexible two dimensional lateral ferroelectric tunnel junctions.", "author_names": [ "Xin-Wei Shen", "Yue-Wen Fang", "Bobo Tian", "Chungang Duan" ], "corpus_id": 182952897, "doc_id": "182952897", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Two Dimensional Ferroelectric Tunnel Junction: The Case of Monolayer In:SnSe/SnSe/Sb:SnSe Homostructure", "venue": "ACS Applied Electronic Materials", "year": 2019 }, { "abstract": "Abstract The ferroelectric tunnel junction represents a memory concept that allows a nondestructive readout by utilizing a very thin ferroelectric film between two metal electrodes. Application of an electric field across the thin ferroelectric changes the polarization orientation and an accompanying modulation of the barrier height of the stack, which alters the tunneling current. For a long time, this concept was neglected due to the expected difficulties using common perovskite ferroelectrics and epitaxy for depositing such a thin layer while maintaining high ferroelectric properties. The discovery of ferroelectricity in the hafnium oxide system represents a game changer. In this chapter, the crucial design parameters are discussed that have to be considered for controlling the current transport, reducing the depolarization field, and finally optimizing the tunneling electroresistance effect.", "author_names": [ "Shosuke Fujii", "Masumi Saitoh" ], "corpus_id": 141402471, "doc_id": "141402471", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Ferroelectric Tunnel Junction", "venue": "", "year": 2019 }, { "abstract": "We have developed a numerical simulation framework for HfO2 based Ferroelectric Tunnel Junction (FTJ) memory using Non Equilibrium Green Function (NEGF) and self consistent potential method which is calibrated by our experimental FTJ results. Scalability and design guideline of Metal Ferroelectric Insulator Semiconductor (MFIS) structure FTJ is investigated in this work. Due to the large asymmetry of dielectric screening length of MFIS structure FTJ electrodes, MFIS structure FTJ shows a higher tunneling electroresistance (TER) ratio than Metal Ferroelectric Insulator Metal (MFIM) structure FTJ, while it has almost the same read current as MFIM structure FTJ. High read current and high TER ratio can be obtained by adjusting property of semiconductor bottom electrodes. A guideline of designing MFIS structure FTJ has been proposed for high read current and high TER ratio. MFIS type FTJ shows a potential for scaling down to sub 20 nm diameter.", "author_names": [ "Fei Mo", "Yusaku Tagawa", "Takuya Saraya", "Toshiro Hiramoto", "Masaharu Kobayashi" ], "corpus_id": 211121031, "doc_id": "211121031", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Scalability Study on Ferroelectric HfO2 Tunnel Junction Memory Based on Non equilibrium Green Function Method", "venue": "2019 19th Non Volatile Memory Technology Symposium (NVMTS)", "year": 2019 }, { "abstract": "Abstract This paper proposes a device incorporating ferroelectric tunnel junction which analyzes the concept of tunneling across a silicon doped hafnium oxide ferroelectric. Variation of electrical parameters with ferroelectric thickness has been examined. Subthreshold swing (SS) of 40 mV/dec has been achieved with ferroelectric thickness of 2 nm. An increasing trend in the ION/IOFF ratio is observed with the increase in ferroelectric thickness. Moreover, the impact of temperature (300 K 500 K) on drain current as well as various RF parameter performance such as gate capacitance (CGG) transconductance (gm) output conductance (gd) intrinsic delay, intrinsic gain (gm/gd) cut off frequency (ft) and transconductance frequency product (TFP) has been studied.", "author_names": [ "Pujarini Ghosh", "Rupam Goswami", "Brinda Bhowmick" ], "corpus_id": 203994986, "doc_id": "203994986", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Optimization of ferroelectric tunnel junction TFET in presence of temperature and its RF analysis", "venue": "Microelectron. J.", "year": 2019 }, { "abstract": "Abstract The electroresistance in silicene based normal/ferroelectric gated/normal junction is investigated. The energy gap in silicene can be tuned by electric field. The spontaneous electric polarization in ferroelectric (FE) can be switched by external electric field. Due to the combination of these properties, we find that the studied junction may generate tunneling electroresistance (TER) exceeding 109% The conductance ratio of ON to OFF state, GON/GOFF, is found to be larger than 107, enhanced by increasing the thickness of the barrier or increasing the magnitude of electric polarization in the FE layer. The giant TER effect is directly related to the buckled lattice and the presence of spin orbit interaction in silicene. This work reveals the potential of silicene as a good material for application of ferroelectric random access memory.", "author_names": [ "Assanai Suwanvarangkoon", "Bumned Soodchomshom" ], "corpus_id": 123431922, "doc_id": "123431922", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Giant tunneling electroresistance in ferroelectric gated silicene junction", "venue": "", "year": 2015 }, { "abstract": "Abstract We report successful synthesis of superconducting Bi Sr Ca Cu2 OX (BSCCO) target for fabrication of heterostructure thin films. For the first time, we have grown LSMO (50 nm)/PZT (5 nm)/BSCCO (100 nm)/LAO (100) heterostructure by pulsed laser deposition technique to understand the tunneling effect and role of the superconducting electrode on transport and magnetic properties. The bulk superconductor Bi Sr Ca Cu2 OX (BSCCO) and heterostructure shows superconducting phase transition near 92 K and 110 K, respectively. Magnetic susceptibility data indicate large negative susceptibility below 110 K which confirms the superconducting nature of heterostructure bottom electrode. A large hysteresis in current voltage data has been obtained at 78 K below the superconducting state of bottom electrode. These results suggest that the ferromagnetic/ferroelectric/superconductor tunnel structure may provide four distinct resistance states depending on the direction of ferroelectric polarization.", "author_names": [ "", "V N Ojha", "Ashok Kumar" ], "corpus_id": 106391404, "doc_id": "106391404", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Fabrication of ferroelectric tunnel junction using superconducting and magnetic electrodes", "venue": "", "year": 2019 }, { "abstract": "Brain inspired neuromorphic computing has shown great promise beyond the conventional Boolean logic. Nanoscale electronic synapses, which have stringent demands for integration density, dynamic range, energy consumption, etc. are key computational elements of the brain inspired neuromorphic system. Ferroelectric tunneling junctions have been shown to be ideal candidates to realize the functions of electronic synapses due to their ultra low energy consumption and the nature of ferroelectric tunneling. Here, we report a new electronic synapse based on a three dimensional vertical Hf0.5Zr0.5O2 based ferroelectric tunneling junction that meets the full functions of biological synapses. The fabricated three dimensional vertical ferroelectric tunneling junction synapse (FTJS) exhibits high integration density and excellent performances, such as analog like conductance transition under a training scheme, low energy consumption of synaptic weight update (1.8 pJ per spike) and good repeatability >103 cycles) In addition, the implementation of pattern training in hardware with strong tolerance to input faults and variations is also illustrated in the 3D vertical FTJS array. Furthermore, pattern classification and recognition are achieved, and these results demonstrate that the Hf0.5Zr0.5O2 based FTJS has high potential to be an ideal electronic component for neuromorphic system applications.", "author_names": [ "Lin Chen", "Tian-Yu Wang", "Ya-Wei Dai", "Ming-Yang Cha", "Hao Zhu", "Qingqing Sun", "S J Ding", "Peng Zhou", "Leon Ong Chua", "David-Wei Zhang" ], "corpus_id": 206136502, "doc_id": "206136502", "n_citations": 60, "n_key_citations": 0, "score": 1, "title": "Ultra low power Hf0.5Zr0.5O2 based ferroelectric tunnel junction synapses for hardware neural network applications.", "venue": "Nanoscale", "year": 2018 }, { "abstract": "Theoretical investigations of ferroelectric tunneling in a SrRuO3/BaTiO3/Pt junction were conducted, and critical expressions for the surface charge density in the electrodes and the potential distribution across the tunnel junction were derived. It was found that the screening charges associated with the ferroelectric polarization and the charging effect of the capacitor jointly contribute to the charges in the electrodes. A current voltage study simulating the 'read' operation indicated that the tunneling electroresistance effect increases with the ferroelectric thickness, and the tunneling electroresistance values agree well with experimental results.", "author_names": [ "Zhijun Ma", "G Chen", "Peng Zhou", "Zhiheng Mei", "Tianjin Zhang" ], "corpus_id": 126131643, "doc_id": "126131643", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Ferroelectric tunneling under bias voltages", "venue": "", "year": 2017 }, { "abstract": "The ferroelectric material is one of the important platforms to realize non volatile memories. So far, existing ferroelectric memory devices utilize out of plane polarization in ferroelectric thin films. In this paper, we propose a new type of random access memory (RAM) based on ferroelectric thin films with the in plane polarization called \"in plane ferroelectric tunneling junction\" Apart from non volatility, lower power usage and faster writing operation compared with traditional dynamic RAMs, our proposal has the advantage of non destructive reading process, thus overcomes the write after read problem that widely exists in current ferroelectric RAMs, and faster reading operation. The recent discovered room temperature ferroelectric IV VI semiconductor thin films is a promising material platform to realize our proposal.", "author_names": [ "Huitao Shen", "Junwei Liu", "Kai Chang", "Liang Fu" ], "corpus_id": 51790284, "doc_id": "51790284", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "In Plane Ferroelectric Tunnel Junction", "venue": "Physical Review Applied", "year": 2019 }, { "abstract": "Abstract The effect of bias voltage on electron tunneling across a junction with a ferroelectric ferromagnetic composite barrier is investigated theoretically. Because of the inversion symmetry breaking of the spontaneous ferroelectric polarization, bias voltage dependence of the electron tunneling shows significant differences between the positive bias and the negative one. The differences of spin filtering or tunnel magnetoresistance increase with the increasing absolute value of bias voltage. Such direction preferred electron tunneling is found intimately related with the unusual asymmetry of the electrical potential profile in two phase composite barrier and provides a unique change to realize rectifying functions in spintronics.", "author_names": [ "Jian Wang", "Sheng Ju", "Zongyao Li" ], "corpus_id": 120506707, "doc_id": "120506707", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Bias voltage effect on electron tunneling across a junction with a ferroelectric ferromagnetic two phase composite barrier", "venue": "", "year": 2012 } ]

[ { "abstract": "The CH3NH3PbI3 based photodetectors were fabricated with a coplanar metal semiconductor metal (MSM) IDT patterned Au electrode configuration. The MSM structured perovskite based photodetectors exhibited a higher Ion/Ioff of about 3.77 x 102, and a response of 6.66 mA/W. Additionally, the photodetectors worked best under red illumination, and the rise and decay times were estimated to shorter than 0.04 s and 0.05 s. Especially, the durability and stability of these photodetectors were excellent, which can be exposed to the red light illumination over 1000 s. There were still stable photocurrent signal after 90 days. It indicated that the device possessed a longer durability and had a lifetime of exceeding 90 days. These outstanding performances could be potentially applicable for practical applications.", "author_names": [ "Fuqiang Guo", "Xiaohang Li", "Baohua Zhang", "Lili Zhang", "Haineng Bai", "Zheng Guo Zhang", "Qian Yang", "Yang Tan", "Xuebo Liu", "Yihua Song", "Yineng Huang" ], "corpus_id": 203928798, "doc_id": "203928798", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Durable and stable UV Vis perovskite photodetectors based on CH3NH3PbI3 crystals synthesized via a solvothermal method", "venue": "Journal of Materials Science: Materials in Electronics", "year": 2019 }, { "abstract": "Low dimensional lead free organic inorganic hybrid perovskites have gained increasing attention as having low toxicity, ease of processing, and good optoelectronic properties. Seeking for lead free and narrow band gap organic inorganic hybrid perovskites are of great importance for the development and application of photoelectric materials. Here, we reported a Sb based organic inorganic hybrid perovskite (MV)[SbI3Cl2] which has one dimensional inorganic frameworks of the I sharing double octahedra. (MV)[SbI3Cl2] shows a narrow direct band gap of 1.5 eV, and displays obvious photoresponse for the 532 nm light with rapid response speed of trise 0.69 s, tdecay 0.28 s. With an illumination power of 5 mW and a 50 V bias, the responsivities (R) and external quantum efficiency (EQE) for (MV)[SbI3Cl2] photodetector under 532 nm laser are 29.75 mA/W and 6.69% respectively. This Sb based halide double perovskite material will provide an alternative material for photodetector devices.", "author_names": [ "Yun Lei", "Shouyu Wang", "Jie Xing", "Hanqi Xu", "Jing Han", "Weifang Liu" ], "corpus_id": 214644033, "doc_id": "214644033", "n_citations": 9, "n_key_citations": 0, "score": 1, "title": "High Performance UV Vis Photodetectors Based on a Lead Free Hybrid Perovskite Crystal (MV)[SbI3Cl2]", "venue": "Inorganic chemistry", "year": 2020 }, { "abstract": "Organolead halide perovskite has recently emerged as a star material for various photoelectronic devices owing to its excellent optical and electronic properties. However, it is challenging to deve.", "author_names": [ "Fobao Huang", "Ying-quan Peng", "Guohan Liu" ], "corpus_id": 146097017, "doc_id": "146097017", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Toward Ultrahigh Sensitivity and UV Vis NIR Broadband Response of Organolead Halide Perovskite/Tin Phthalocyanine Heterostructured Photodetectors", "venue": "The Journal of Physical Chemistry C", "year": 2019 }, { "abstract": "A lateral photodetector based on the bilayer composite film of a perovskite and a conjugated polymer is reported. It exhibits significantly enhanced responsivity in the UV vis region and sensitive photoresponse in the near IR (NIR) region at a low applied voltage. This broadband photodetector also shows excellent mechanical flexibility and improved environmental stability.", "author_names": [ "Shan Chen", "Changjiu Teng", "Miao Zhang", "Yingru Li", "Dan Xie", "Gaoquan Shi" ], "corpus_id": 12906186, "doc_id": "12906186", "n_citations": 235, "n_key_citations": 1, "score": 0, "title": "A Flexible UV Vis NIR Photodetector based on a Perovskite/Conjugated Polymer Composite.", "venue": "Advanced materials", "year": 2016 }, { "abstract": "Methylammonium lead halide perovskites have been reported to be promising candidates for high performance photodetectors. However, self powered broadband ultraviolet visible near infrared (UV Vis NIR) photodetection with high responsivity is difficult to achieve in these materials. Here, we demonstrate, for the first time, a novel trilayer hybrid photodetector made by combining an n type Si wafer, TiO2 interlayer and perovskite film. By precisely controlling the thickness of the TiO2 layer, enhanced separation and reduced recombination of carriers at the Si perovskite interface are obtained. As a result, perovskite film, when combined with a low bandgap Si, extends the wavelength range of photo response to 1,150 nm, along with improved on/off ratio, responsivity, and specific detectivity, when compared to pristine perovskite. Results obtained in this work are comparable or even better than those reported for perovskite based UV Vis NIR photodetectors. In particular, the hybrid photodetectors can operate in a self powered mode. The mechanism of enhancement has been explored and it is found that the increased separation and reduced recombination of photogenerated carriers at the junction interface leads to the improved performance.", "author_names": [ "Fengren Cao", "Qingliang Liao", "Kaimo Deng", "Liang Chen", "Liang Li", "Yue Kan Zhang" ], "corpus_id": 139622396, "doc_id": "139622396", "n_citations": 27, "n_key_citations": 0, "score": 0, "title": "Novel perovskite/TiO2/Si trilayer heterojunctions for high performance self powered ultraviolet visible near infrared (UV Vis NIR) photodetectors", "venue": "Nano Research", "year": 2018 }, { "abstract": "DOI: 10.1002/adom.201800324 yields with narrow emission bandwidth, size tunable optical properties, strong optical absorption, and more impor tantly, good environmental stabilities.[1 3] They have also been applied to develop high performance solar cells, light emit ting diodes (LEDs) and lasers.[4 7] Several recent works[8 11] have pioneered the appli cation of IPQDs in photodetectors with vertical (photodiode) and lateral (photo conductor and photo transistor) device structures. However, most of them show low responsivity up to 0.64 A W 1. The reported responsivities of IPQD devices are limited by poor carrier mobility due to the choice of interparticle ligand mate rials and high density of defect states.[12] To develop highresponsivity photodetec tors, it is vital to increase carrier diffu sion length. One approach is to decrease the density of defects and increase car rier mobility, which has been a prevalent research topic.[13] However, an alternative method to increase responsivity is to separate electrons and holes into different paths and suppress radiative recombination with the aid of layered heterojunction (LHJ)[14] This strategy should facili tate the extractions of generated carriers and thus increase the photocurrent. There are some recent works adopting this strategy and thus improving the responsivity. Zhou et al.[15] fab ricated CsPbBr3 QD/TiO2 compositebased photodetectors and obtained a 44fold responsivity enhancement compared to pris tine CsPbBr3 QD photodetectors over the detection range from 350 to 550 nm. Chen et al.[16] reported hybrid phototransistors based on CsPbBr3 QD/DTT heterojunctions and achieved the responsivity up to 1.7 x 104 A W 1, however, the detection range only reached up to green wavelength on the long side. Kwak et al.[17] fabricated CsPbBr3 xIx QD/graphene bilayer photode tectors, exhibiting a very high responsivity (108 A W 1) but a decent onoff ratio, the detection wavelength range is limited up to 650 nm. These findings encourage us to use a LHJ film in the photodetector to enhance the performance. Although such IPQDbased hybrid photodetectors exhibit high respon sivity, the detection wavelength regions are still restricted to ultravioletvisible (UV vis) range and cannot reach near infrared (NIR) region. Furthermore, among all reported IPQD detectors, few of them are based on CsPbI3 QDs and targeted All inorganic perovskite quantum dots (IPQDs) are a promising material for use in various optoelectronic devices due to their excellent optoelectronic properties and high environmental stability. Here, a high performance phototransistor based on a layered heterojunction composed of CsPbI3 QDs and a narrow bandgap conjugated polymer DPP DTT is reported, which shows a high responsivity of 110 A W 1, a specific detectivity of 2.9 x 1013 Jones and a light to dark current ratio up to 6 x 103. The heterojunction phototransistor exhibits unipolar p type and gate bias modulated behaviors. In addition, the device exhibits a broad spectral detection range from ultraviolet to near infrared. The high sensitivity of the device is attributed to the layered heterojunction and the gate bias modulation property. The work overcomes the existing limitations in sensitivity of IPQD photodetectors due to the poor charge transport between QDs. The convenient solution processed fabrication and excellent device performance especially suggest the IPQD/narrow bandgap conjugate polymer heterojunction as a promising structure for potential applications of ultrasensitive broadband photodetectors compatible with a wide variety of substrates.", "author_names": [ "Chen Zou", "Yuyin Xi", "Chun-Ying Huang", "Ethan G Keeler", "Tianyu Feng", "Shihao Zhu", "Lilo D Pozzo", "Lih Y Lin" ], "corpus_id": 51915490, "doc_id": "51915490", "n_citations": 24, "n_key_citations": 0, "score": 0, "title": "A Highly Sensitive UV vis NIR All Inorganic Perovskite Quantum Dot Phototransistor Based on a Layered Heterojunction", "venue": "", "year": 2018 }, { "abstract": "Hybrid organic inorganic perovskites have been demonstrated as promising candidates for broadband responsive photodetectors. It is critical to develop perovskite based photodetectors with excellent photodetection capability and facile fabrication processes for practical application. Herein, we designed and fabricated, for the first time, a hybrid photodetector consisting of electrospun ZnO nanofibers and perovskites. Compared to pristine ZnO or perovskite, the hybrid photodetector showed increased on off ratio, faster response speed, and higher responsivity and detectivity. The performance of the hybrid devices was significantly enhanced by using quasi aligned ZnO nanofiber arrays instead of disordered nanofibers, which provide efficient charge transfer between the perovskite and ZnO, shorter transmission paths, and reduced carrier loss at cross junctions of nanofibers. Our results provide a new and promising route to integrate inorganic functional materials with perovskite for high performance and low cost photodetectors.", "author_names": [ "Fengren Cao", "Wei Tian", "Bangkai Gu", "Yulong Ma", "Hao Lu", "Liang Li" ], "corpus_id": 136290366, "doc_id": "136290366", "n_citations": 53, "n_key_citations": 0, "score": 0, "title": "High performance UV vis photodetectors based on electrospun ZnO nanofiber solution processed perovskite hybrid structures", "venue": "Nano Research", "year": 2017 }, { "abstract": "", "author_names": [ "Feng-xia Liang", "Lin Liang", "Xing-yuan Zhao", "Lin-Bao Luo", "Yu-Hung Liu", "Xiao-Wei Tong", "Zhi-Xiang Zhang", "J C Huang" ], "corpus_id": 104452710, "doc_id": "104452710", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "A Sensitive Broadband (UV vis NIR) Perovskite Photodetector Using Topological Insulator as Electrodes", "venue": "", "year": 2018 }, { "abstract": "We report a high performance phototransistor based on a layered heterojunction composed of all inorganic perovskite quantum dots (IPQDs) and a narrow bandgap conjugated polymer DPP DTT. The device exhibits stable and excellent optoelectronic properties with broadband photodetection range.", "author_names": [ "Chen Zou", "Yuyin Xi", "Lilo D Pozzo", "Lih Y Lin" ], "corpus_id": 51975773, "doc_id": "51975773", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Highly Sensitive UV Vis NIR Inorganic Perovskite Quantum Dot Phototransistors Based on Layered Heterojunctions", "venue": "2018 Conference on Lasers and Electro Optics (CLEO)", "year": 2018 }, { "abstract": "We present an investigation of the ultrafast charge carrier dynamics for the one third metal deficient lead free perovskite (CH3NH3)3Bi2I9 on mesoporous TiO2. Excitation of the perovskite at 400 or 505 nm leads to characteristic second derivative type spectral features in the transient absorption spectra, suggesting substantial contributions of bound excitons, in contrast to the widely used lead based perovskites. The immediate appearance of broad NIR absorption is assigned to TiO2 conduction band electrons formed by instantaneous dissociation of a subpopulation of excitons at the perovskite/TiO2 interface. Excitation with excess energy above the perovskite's band gap opens up an additional fast (70 fs) exciton dissociation channel with about 26% amplitude. Antisolvent assisted synthesis of (CH3NH3)3Bi2I9 reduces the crystallite size to about 500 nm but has only a minor effect on the carrier dynamics. The results suggest that photovoltaic applications of this material will likely require bulk heterojuncti.", "author_names": [ "Mirko Scholz", "Oliver Flender", "Kawon Oum", "Thomas Lenzer" ], "corpus_id": 98927647, "doc_id": "98927647", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "Pronounced Exciton Dynamics in the Vacancy Ordered Bismuth Halide Perovskite (CH3NH3)3Bi2I9 Observed by Ultrafast UV vis NIR Transient Absorption Spectroscopy", "venue": "", "year": 2017 } ]

[ { "abstract": "Fluorescent carbon nanoparticles or carbon quantum dots (CQDs) are a new class of carbon nanomaterials that have emerged recently and have garnered much interest as potential competitors to conventional semiconductor quantum dots. In addition to their comparable optical properties, CQDs have the desired advantages of low toxicity, environmental friendliness low cost and simple synthetic routes. Moreover, surface passivation and functionalization of CQDs allow for the control of their physicochemical properties. Since their discovery, CQDs have found many applications in the fields of chemical sensing, biosensing, bioimaging, nanomedicine, photocatalysis and electrocatalysis. This article reviews the progress in the research and development of CQDs with an emphasis on their synthesis, functionalization and technical applications along with some discussion on challenges and perspectives in this exciting and promising field.", "author_names": [ "Shi Ying Lim", "Wei Shen", "Zhiqiang Gao" ], "corpus_id": 19393519, "doc_id": "19393519", "n_citations": 2473, "n_key_citations": 21, "score": 1, "title": "Carbon quantum dots and their applications.", "venue": "Chemical Society reviews", "year": 2015 }, { "abstract": "Strategies for selectively imaging and delivering drugs to tumours typically leverage differentially upregulated surface molecules on cancer cells. Here, we show that intravenously injected carbon quantum dots, functionalized with multiple paired a carboxyl and amino groups that bind to the large neutral amino acid transporter 1 (which is expressed in most tumours) selectively accumulate in human tumour xenografts in mice and in an orthotopic mouse model of human glioma. The functionalized quantum dots, which structurally mimic large amino acids and can be loaded with aromatic drugs through p p stacking interactions, enabled in the absence of detectable toxicity near infrared fluorescence and photoacoustic imaging of the tumours and a reduction in tumour burden after the targeted delivery of chemotherapeutics to the tumours. The versatility of functionalization and high tumour selectivity of the quantum dots make them broadly suitable for tumour specific imaging and drug delivery. Intravenously injected functionalized carbon quantum dots that bind to the large neutral amino acid transporter 1 and that structurally mimic large amino acids selectively accumulate in human tumours in mice, facilitating targeted theranostics.", "author_names": [ "Shuhua Li", "Wen Su", "Hao Wu", "Ting Yuan", "Chang Yuan", "Jun Liu", "Gang Deng", "Xingchun Gao", "Zeming Chen", "Youmei Bao", "Fanglong Yuan", "Shixin Zhou", "Hongwei Tan", "Yunchao Li", "Xiaohong Li", "Louzhen Fan", "Jia Zhu", "Ann Tai Chen", "Fuyao Liu", "Yu Zhou", "Miao Li", "Xingchen Zhai", "Jiangbing Zhou" ], "corpus_id": 214704171, "doc_id": "214704171", "n_citations": 45, "n_key_citations": 1, "score": 1, "title": "Targeted tumour theranostics in mice via carbon quantum dots structurally mimicking large amino acids", "venue": "Nature Biomedical Engineering", "year": 2020 }, { "abstract": "Efficient full color fluorescent carbon quantum dots are synthesized by acid reagent engineering for white light emitting devices. Quantum dots have innate advantages as the key component of optoelectronic devices. For white light emitting diodes (WLEDs) the modulation of the spectrum and color of the device often involves various quantum dots of different emission wavelengths. Here, we fabricate a series of carbon quantum dots (CQDs) through a scalable acid reagent engineering strategy. The growing electron withdrawing groups on the surface of CQDs that originated from acid reagents boost their photoluminescence wavelength red shift and raise their particle sizes, elucidating the quantum size effect. These CQDs emit bright and remarkably stable full color fluorescence ranging from blue to red light and even white light. Full color emissive polymer films and all types of high color rendering index WLEDs are synthesized by mixing multiple kinds of CQDs in appropriate ratios. The universal electron donating/withdrawing group engineering approach for synthesizing tunable emissive CQDs will facilitate the progress of carbon based luminescent materials for manufacturing forward looking films and devices.", "author_names": [ "Liang Wang", "Weitao Li", "Luqiao Yin", "Yijiang Liu", "Huazhang Guo", "Jiawei Lai", "Yu Han", "Gao Li", "Ming Li", "Jianhua Zhang", "Robert Vajtai", "Pulickel M Ajayan", "Minghong Wu" ], "corpus_id": 222110938, "doc_id": "222110938", "n_citations": 46, "n_key_citations": 0, "score": 0, "title": "Full color fluorescent carbon quantum dots", "venue": "Science Advances", "year": 2020 }, { "abstract": "Abstract Currently, the disposal of municipal wastes (paper, plastic, and coffee residue) is a problem due to increasing the amount of municipal wastes, global environmental problems, and high disposal cost. Here, we report the synthesis of carbon quantum dots from waste paper by different solvents by a conventional hydro /solvothermal method for solving the environmental and disposal problems. The carbon quantum dots synthesized with waste papers have several advantages such as low toxicity, low cost, and eco friendly. The prepared carbon quantum dots have main emission peak from 440 to 540 nm under 340 480 nm excitation. The prepared carbon quantum dots can be applied to easily prepare anti counterfeiting ink and fluorescent flexible film because of their unique optical property and excellent chemical and photostability.", "author_names": [ "Sung Jun Park", "Jin Young Park", "Jong Won Chung", "Hyun Kyoung Yang", "Byung Kee Moon", "Soung Soo Yi" ], "corpus_id": 208735373, "doc_id": "208735373", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Color tunable carbon quantum dots from wasted paper by different solvents for anti counterfeiting and fluorescent flexible film", "venue": "", "year": 2020 }, { "abstract": "Large doses of anticancer drugs entering cancer cell nuclei are found to be effective at killing cancer cells and increasing chemotherapeutic effectiveness. Here we report red emissive carbon quantum dots, which can enter into the nuclei of not only cancer cells but also cancer stem cells. After doxorubicin was loaded at the concentration of 30 mg/mL on the surfaces of carbon quantum dots, the average cell viability of HeLa cells was decreased to only 21% while it was decreased to 50% for free doxorubicin. The doxorubicin loaded carbon quantum dots also exhibited a good therapeutic effect by eliminating cancer stem cells. This work provides a potential strategy for developing carbon quantum dot based anticancer drug carriers for effective eradication of cancers.", "author_names": [ "Wen Su", "Ruihua Guo", "Fanglong Yuan", "Yunchao Li", "Xiaohong Li", "Yang Zhang", "Shixin Zhou", "Louzhen Fan" ], "corpus_id": 211035565, "doc_id": "211035565", "n_citations": 25, "n_key_citations": 0, "score": 0, "title": "Red Emissive Carbon Quantum Dots for Nuclear Drug Delivery in Cancer Stem Cells.", "venue": "The journal of physical chemistry letters", "year": 2020 }, { "abstract": "Carbon and graphene quantum dots are prepared using top down and bottom up methods. Sustainable synthesis of quantum dots has several advantages such as the use of low cost and non toxic raw materials, simple operations, expeditious reactions, renewable resources and straightforward post processing steps. These nanomaterials are promising for clinical and biomedical sciences, especially in bioimaging, diagnosis, bioanalytical assays and biosensors. Here we review green methods for the fabrication of quantum dots, and biomedical and biotechnological applications.", "author_names": [ "Siavash Iravani", "Rajender S Varma" ], "corpus_id": 212643318, "doc_id": "212643318", "n_citations": 71, "n_key_citations": 1, "score": 0, "title": "Green synthesis, biomedical and biotechnological applications of carbon and graphene quantum dots. A review", "venue": "Environmental Chemistry Letters", "year": 2020 }, { "abstract": "Nitrogen doped carbon quantum dots (N CQDs) were successfully synthesized using rice residue and glycine as carbon and nitrogen sources by one step hydrothermal method. High quantum yield (23.48% originated from the effective combination of nitrogen with various functional groups (CO, NH, CN, COOH and COC) The N CQDs showed a fluorescence with the wavelength varied from 420 to 500 nm and the maximum emission wavelength being at 440 nm. N CQDs have been importantly applied as probe to detect Fe3+ and tetracycline (TCs) antibiotics with remarkable performance. Using the linear relationship between fluorescence intensity and Fe3+ concentration, the N CQDs could be employed as a simple, efficient sensor for ultrasensitive Fe3+ detection ranging from 3.32 to 32.26 uM, with a limit of detection (LOD) of 0.7462 uM. The N CQDs showed the applicability to detect TCs. The detection limits of tetracycline, terramycin and chlortetracycline were 0.2367, 0.3739 and 0.2791 uM, respectively. The results of TC by fluorescence method in real water samples were in good agreement with standard Ultraviolet visible (UV vis) method. The N CQDs have various potential applications including sensitive and selective detection of Fe3+ and TCs, and cellular imaging with low cytotoxicity, good biocompatibility and high permeability.", "author_names": [ "Houjuan Qi", "Min Teng", "Miao Liu", "Shouxin Liu", "Jian Li", "Haipeng Yu", "Chunbo Teng", "Zhanhua Huang", "Hu Liu", "Qian Shao", "Ahmad Umar", "Tao Ding", "Qiang Gao", "Zhanhu Guo" ], "corpus_id": 58602387, "doc_id": "58602387", "n_citations": 187, "n_key_citations": 1, "score": 0, "title": "Biomass derived nitrogen doped carbon quantum dots: highly selective fluorescent probe for detecting Fe3+ ions and tetracyclines.", "venue": "Journal of colloid and interface science", "year": 2019 }, { "abstract": "Therapeutic options for the highly pathogenic human coronavirus (HCoV) infections are urgently needed. Anticoronavirus therapy is however challenging, as coronaviruses are biologically diverse and rapidly mutating. In this work, the antiviral activity of seven different carbon quantum dots (CQDs) for the treatment of human coronavirus HCoV 229E infections was investigated. The first generation of antiviral CQDs was derived from hydrothermal carbonization of ethylenediamine/citric acid as carbon precursors and postmodified with boronic acid ligands. These nanostructures showed a concentration dependent virus inactivation with an estimated EC50 of 52 8 mg mL 1. CQDs derived from 4 aminophenylboronic acid without any further modification resulted in the second generation of anti HCoV nanomaterials with an EC50 lowered to 5.2 0.7 mg mL 1. The underlying mechanism of action of these CQDs was revealed to be inhibition of HCoV 229E entry that could be due to interaction of the functional groups of the CQDs with HCoV 229E entry receptors; surprisingly, an equally large inhibition activity was observed at the viral replication step.", "author_names": [ "Aleksandra Loczechin", "Karin Seron", "Alexandre Barras", "Emerson Giovanelli", "Sandrine Belouzard", "Yen-Ting Chen", "Nils Metzler-Nolte", "Rabah Boukherroub", "Jean Dubuisson", "Sabine Szunerits" ], "corpus_id": 204814784, "doc_id": "204814784", "n_citations": 104, "n_key_citations": 2, "score": 0, "title": "Functional Carbon Quantum Dots as Medical Countermeasures to Human Coronavirus", "venue": "ACS applied materials interfaces", "year": 2019 }, { "abstract": "Abstract Microbial contamination and antibiotic pollutions diffusely exist in wastewater system, and contaminated water poses a threat to public health. Therefore, there is a need to effectively remove biohazard and antibiotic contamination from wastewater systems. In this paper, sulfur doped carbon quantum dots (S CQDs)/hollow tubular g C3N4 photocatalyst (HTCN C) prepared via ultrasonic assisted synthesis strategy, was regarded as an efficient catalyst for the degradation of antibiotic (tetracycline) and destruction of a typical Gram negative bacterium (Escherichia coli) in imitated wastewater system. The unique structures of hollow tubular g C3N4 and loading of modified carbon quantum dots enhanced electron transfer and charge separation, leading to a significant improvement in photocatalytic efficiency. Benefiting from these merits, the optimized catalysts (HTCN C(2) exhibited superior performance with a reaction rate of 0.0293 min 1 for tetracycline (TC) degradation and 99.99% destruction of Escherichia coli under visible light irradiation. Moreover, the characterization of UV Vis diffuse reflectance spectra, photoluminescence technique, transient photocurrent responses and electrochemical impedance spectroscopy also verified the good optical and electrochemical properties of resultant samples. Our current work indicates that HTCN C has great potential in degradation of antibiotic and destruction of bacterium for practical wastewater treatment.", "author_names": [ "Wenjun Wang", "Zhuotong Zeng", "Guangming Zeng", "Chen Zhang", "Rong Xiao", "Chengyun Zhou", "Weiping Xiong", "Yongxiang Yang", "Lei Lei", "Yang Liu", "Danlian Huang", "Min Cheng", "Ya-Ya Yang", "Yukui Fu", "Hanzhuo Luo", "Yin Zhou" ], "corpus_id": 198367887, "doc_id": "198367887", "n_citations": 169, "n_key_citations": 0, "score": 0, "title": "Sulfur doped carbon quantum dots loaded hollow tubular g C3N4 as novel photocatalyst for destruction of Escherichia coli and tetracycline degradation under visible light", "venue": "", "year": 2019 }, { "abstract": "Carbon quantum dots (CQDs) are a member of carbon nanostructures family which have received increasing attention for their photoluminescence (PL) physical and chemical stability and low toxicity. The classical semiconductor quantum dots (QDs) are semiconductor particles that are able to emit fluorescence by excitation. The CQDs is mainly referred to photoluminescent carbon nanoparticles less than 10 nm, with surface modification or functionalization. Contrary to other carbon nanostructures, CQDs can be synthesized and functionalized fast and easily. The fluorescence origin of the CQDs is a controversial issue which depends on carbon source, experimental conditions, and functional groups. However, PL emissions originated from conjugated p domains and surface defects have been proposed for the PL emission mechanisms of the CQDs. These nanostructures have been used as nontoxic alternatives to the classical heavy metals containing semiconductor QDs in some applications such as in vivo and in vitro bio imaging, drug delivery, photosensors, chemiluminescence (CL) and etc. This paper will introduce CQDs, their structure, and PL characteristics. Recent advances of the application of CQDs in biotechnology, sensors, and CL is comprehensively discussed.", "author_names": [ "Mohammad Jafar Molaei" ], "corpus_id": 59274823, "doc_id": "59274823", "n_citations": 159, "n_key_citations": 0, "score": 0, "title": "A review on nanostructured carbon quantum dots and their applications in biotechnology, sensors, and chemiluminescence.", "venue": "Talanta", "year": 2019 } ]

[ { "abstract": "photovoltaic Effect? Haiyang Zou, Chunli Zhang, Hao Xue, Zhiyi Wu, and Zhong Lin Wang* +School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 0245, United States +Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, P.R. China The photovoltaic effect in p n junctions has been widely studied and used to work as renewable energy sources for portable devices and various appliances. Due to the band gap energy of semiconductors in p n junctions, carriers are excited by light and then are separated by an internal electric field built in the interface of the junctions, so that the light can be efficiently absorbed and converted into electricity. Nevertheless, the open circuit voltage is limited by the band gap energy of the semiconductors. The bulk photovoltaic (BPV) effect, caused by the asymmetric distribution of photoexcited carriers in momentum space, can generate a large photovoltage under uniform illumination, which is far beyond its band gap of the corresponding semiconductor. However, the power generation efficiency is very low due to the unusually low short circuit current, and the materials that exhibit the BPV effect are generally wide band gap noncentrosymmetric materials. Yang et al. reported the flexo photovoltaic (FPV) effect in which the BPV effect can be induced by strain gradients in any semiconductor through the flexoelectric effect. The authors claimed that the strain gradients create very large photovoltaic currents from centrosymmetric single crystals. A silicon made atomic force microscopy (AFM) tip with a typical radius size of only 8 nm was pressed on a single crystal with a size of more than 0.5 cmx 0.5 cmwith a thickness of more than 0.5 mm to induce strain gradients on the bulk materials. They claimed \"the current increases by more than a factor of 100 when the loading force increased from 1 to 18 mN\" (actually, from Figure S12A, the current increased by only 3.39 times when the force increased from 1 to 15 mN) The nanosized AFM tip was treated as an ideal rigid spherical indenter, and the Hertzian model was applied to calculate the strain and strain gradient in order to confirm this AFM tip could generate the flexoelectric effect in bulk materials. The author claimed that the flexo photovoltaic effect was discovered as the photocurrent has a dependence on crystallographic orientation and the light polarization with an amplitude of less than 2 pA. Above all, they believed this FPV effect played a dominating role in the increased photocurrent under strains. Here, we focus on four aspects to discuss the data, mechanisms, and conclusions presented in Yang's paper and clarify some facts. First, the experimental design is unreasonable as many other issues involved are not properly addressed when the authors drew the conclusions. Second, the physical models adopted for the calculation analysis are irrational, and the results are based on unrealistic assumptions that far exceed the properties of any materials known. Third, the proposed physical model is based on speculation, and the experimental results do not fully support the physical model. Fourth, the statements made in the discussions and conclusions sections are misleading. Therefore, there are many questions and doubts to be clarified, and many statements need to be corrected. We provide some advice on both experimental methods and theoretical models toward the exact quantification of the FPV effect, which are fundamental and critical, to avoid misleading the scientific community and the public readers by the work from Yang and co authors. More details are elaborated as follows. The Unreasonable Experimental Measurement and Design. Flexoelectricity effect is a coupling effect between electric polarization and strain gradient in centrosymmetric material, which was discovered several decades ago. Studies of flexoelectricity in solids have been scarce due to the extremely small magnitude of this effect in bulk samples. The current studies are mainly focused on materials/structures at the nanoscale as the large strain gradients in nanomaterials can lead to a strong flexoelectric effect. Strain gradients are inversely proportional to size, so thin films are the obvious place to look for flexoelectric effects. Because whenever the thickness exceeds some critical value, the materials may relieve the stress by a formation of misfit dislocations or by twinning, whether the materials are single crystals or not. Yang et al. applied a point force exerted by the tip of a custom made photoelectric atomic force microscope on the bulk materials with a size of more than 0.5 cmx 0.5 cm with a thickness of more than 0.5 mm to induce strain gradients on the bulkmaterials. Yang et al. did not try to do any experiment to verify whether the flexoelectric effect has been induced or not or measure the strength of the flexoelectric effect induced by the strains. Such important data are missing, and we cannot conclude that the AFM tip can generate the flexoelectric effect on these materials. Every material and every sample is different, including various Young's modules, surface roughness, defects, and it is inappropriate to guess that the effect can be obtained by comparing with other papers unless it has been verified experimentally. However, the polarization induced by the applied force has never been measured and verified. A conductive AFM probe was employed for both applying pressure and acting as a conductive electrode. Such a design involves many complicated problems and errors. Smooth surfaces, even those polished, are never perfectly flat on a microscopic scale due to asperities. They are rough, with sharp or rugged projections (Figure 1a,b) Single crystals are never atomically flat after the processes of manufacturing and cutting.", "author_names": [ "Haiyang Zou", "Chunli Zhang", "Hao Xue", "Zhiyi Wu", "Zhong Lin Wang" ], "corpus_id": 208321418, "doc_id": "208321418", "n_citations": 52, "n_key_citations": 0, "score": 1, "title": "Boosting the Solar Cell Efficiency by Flexo photovoltaic Effect?", "venue": "ACS nano", "year": 2019 }, { "abstract": "Poking a semiconductor Noncentrosymmetric crystal structure can lead to a peculiar kind of charge separation under illumination called the bulk photovoltaic (BPV) effect. Solar cells made of such materials, however, typically have low efficiency. Yang et al. expanded the class of materials capable of exhibiting the BPV effect by making ordinarily centrosymmetric materials, such as SrTiO3 and TiO2, lose their inversion symmetry. The authors accomplished this by applying a point force on the surface of the material. This induced a strain gradient and the loss of inversion symmetry, resulting in large photovoltaic currents under illumination. The mechanism, dubbed the flexo photovoltaic effect, is expected to apply to most semiconductors. Science, this issue p. 904 A bulk photoelectric effect is induced in centrosymmetric semiconductors by applying a point force on the materials' surfaces. It is highly desirable to discover photovoltaic mechanisms that enable enhanced efficiency of solar cells. Here we report that the bulk photovoltaic effect, which is free from the thermodynamic Shockley Queisser limit but usually manifested only in noncentrosymmetric (piezoelectric or ferroelectric) materials, can be realized in any semiconductor, including silicon, by mediation of flexoelectric effect. We used either an atomic force microscope or a micrometer scale indentation system to introduce strain gradients, thus creating very large photovoltaic currents from centrosymmetric single crystals of strontium titanate, titanium dioxide, and silicon. This strain gradient induced bulk photovoltaic effect, which we call the flexo photovoltaic effect, functions in the absence of a p n junction. This finding may extend present solar cell technologies by boosting the solar energy conversion efficiency from a wide pool of established semiconductors.", "author_names": [ "Ming-Min Yang", "Dong Jik Kim", "Marin Alexe" ], "corpus_id": 4975732, "doc_id": "4975732", "n_citations": 102, "n_key_citations": 0, "score": 1, "title": "Flexo photovoltaic effect", "venue": "Science", "year": 2018 }, { "abstract": "Lithium ion batteries (LIBs) work under sophisticated external force field and its electrochemical properties could be modulated by strain. Owing to the electro mechanical coupling, the change of micro local structures can greatly affect lithium (Li) diffusion rate in solid state electrolytes and electrode materials of LIBs. In this study, we find that strain gradient in bilayer graphene (BLG) significantly affects Li diffusion barrier, which is termed as the flexo diffusion effect, through first principles calculations. The Li diffusion barrier substantially decreases/increases under the positive/negative strain gradient, leading to the change of Li diffusion coefficient in several orders of magnitude at 300 K. Interestingly, the regulation effect of strain gradient is much more significant than that of uniform strain field, which can have a remarkable effect on the rate performance of batteries, with a considerable increase in the ionic conductivity and a slight change of the original material structure. Moreover, our ab initio molecular dynamics simulations (AIMD) show that the asymmetric distorted lattice structure provides a driving force for Li diffusion, resulting in oriented diffusion along the positive strain gradient direction. These findings could extend present LIBs technologies by introducing the novel strain gradient engineering.", "author_names": [ "Gao Xu", "Feng Hao", "Mouyi Weng", "Jia-wang Hong", "Feng Pan", "Daining Fang" ], "corpus_id": 211096661, "doc_id": "211096661", "n_citations": 3, "n_key_citations": 0, "score": 1, "title": "Flexo diffusion effect: the strong influence on lithium diffusion induced by strain gradient", "venue": "", "year": 2020 }, { "abstract": "Lithium ion batteries (LIBs) work under a sophisticated external force field and the electrochemical properties could be modulated by strain. Owing to electro mechanical coupling, the change of micro local structures can greatly affect the lithium (Li) diffusion rate in solid state electrolytes and the electrode materials of LIBs. In this study, we found, through first principles calculations, that the strain gradient in bilayer graphene (BLG) significantly affects the Li diffusion barrier, which is termed as the flexo diffusion effect. The Li diffusion barrier substantially decreases/increases under a positive/negative strain gradient, leading to a change of Li diffusion coefficient of several orders of magnitude at 300 K. Interestingly, the regulation effect of strain gradient is much more significant than that of a uniform strain field, which can have a remarkable effect on the rate performance of batteries, with a considerable increase in the ionic conductivity and a slight change of the original material structure. Moreover, our ab initio molecular dynamics simulations (AIMD) show that the asymmetric distorted lattice structure provides a driving force for Li diffusion, resulting in oriented diffusion along the positive strain gradient direction. We predict the new phenomenon of a flexo diffusion effect from a theoretical calculation aspect, these findings could extend present LIB technologies by introducing a novel strain gradient engineering.", "author_names": [ "Gao Xu", "Feng Hao", "Mouyi Weng", "Jiawang Hong", "Feng Pan", "Daining Fang" ], "corpus_id": 220527870, "doc_id": "220527870", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Strong influence of strain gradient on lithium diffusion: flexo diffusion effect.", "venue": "Nanoscale", "year": 2020 }, { "abstract": "", "author_names": [ "Yunyun Gong", "Chen Chen", "Faqiang Zhang", "Xiang He", "Huarong Zeng", "Qunbao Yang", "Yongxiang Li", "Zhiguo Yi" ], "corpus_id": 216490341, "doc_id": "216490341", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Ferroelectric photovoltaic and flexo photovoltaic effects in (1 x (Bi 0.5 Na 0.5 )TiO 3 x BiFeO 3 systems under visible light", "venue": "", "year": 2020 }, { "abstract": "", "author_names": [ "Ronggang Cai", "Vlad-Andrei Antohe", "Bernard Nysten", "Luc Piraux", "Alain M Jonas" ], "corpus_id": 214206904, "doc_id": "214206904", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Thermally Induced Flexo Type Effects in Nanopatterned Multiferroic Layers", "venue": "", "year": 2020 }, { "abstract": "In this work, the mechanical aspect of a compact prototype of transhumeral prosthesis with flexo extension and prone supination movements is presented. The torque and maximum speed of the elbow and wrist joints were established based on activities of daily living. Lengths, circumferences, and maximum weight were adjusted to anthropometric measurements of the Latin American population. Materials and transmission mechanisms were selected using property pondering matrices. Safety factors and displacements were checked by means of numerical simulation. The parts were manufactured by machining and 3D printing. The mechanism was assembled and validated using the design loads. The mechanism measures 7 cm from the elbow to the arm coupling. It can move objects up to 450 g with retention and up to 2 kg without retention, with maximum speeds of 30 rpm and 20 rpm for the elbow and wrist joints, respectively. The ranges of movement are flexion, 130deg; extension, 30deg; pronation, 90deg; supination, 90deg. The prototype is compact enough to be used in cases of long amputation. The speeds, ranges of motion and load capabilities are suitable for most activities of daily life.", "author_names": [ "Pablo Tapia", "Marco Ciaccia", "Ivan Iglesias" ], "corpus_id": 227277844, "doc_id": "227277844", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Compact Transhumeral Prosthesis Mechanism with Integrated Flexo Extension and Prone Supination Movements", "venue": "2020 IEEE ANDESCON", "year": 2020 }, { "abstract": "In this study we have aimed to present statistical evaluation of changes in the surface roughness of the solid tone areas on CtP flexo printing plate in dependence of print run. Changes in flexo plate surface roughness is influenced by the plate making process, printing pressure and speed, the interaction with the ink and printing substrate and by the wear of the printing plate due to long print runs. Thus, the aim of this research was to evaluate the changes in the amplitude surface roughness parameters (Ra, Rp, Rv and Rz) between the printing plates used for different print runs. In the experiment, we have employed three sets of CtP flexo printing plates, for three colors cyan, magenta and blue. The first set was not used for printing, the second was used to print 7 rolls of substrate and the third is used to print 11 rolls of printing substrate. The amplitude surface roughness parameters were compared by applying independentsamples t test method using the software SPSS (Statistical Package for Social Science) with a 0.05 significance level. Statistical analysis revealed that the difference between the amplitude surface roughness parameters measured on CtP flexo printing plates are significant with a 95% confidence level, whereas the statistical significance pointed out that with the longer print runs, the difference will be strongly expressed.", "author_names": [ "Sandra Dedijer", "Novi Sad Serbia Design", "Magdolna Pal", "Ivana Tomic", "Stefan Poljak", "Zivko Pavlovic", "Ivana Juric", "Neda Milic Kerestes" ], "corpus_id": 228891031, "doc_id": "228891031", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Statistical analysis of the influence of print run on surface roughness of digital flexo printing plates' solid tone areas", "venue": "", "year": 2020 }, { "abstract": "El acero inoxidable es un material con una respuesta no lineal y con endurecimiento por deformacion, lo que condiciona su diseno con respecto al acero al carbono. El CSM es un nuevo metodo de dimensionamiento que tiene en cuenta el endurecimiento por deformacion en secciones poco esbeltas. SE ha publicado recientemente una propuesta para incluir este efecto en el dimensionamiento a pandeo de pilares comprimidos. En este trabajo se pretende extender dicho metodo a pilares de acero inoxidable flexo comprimidos", "author_names": [ "Shoghi Moreno", "Nur Esteban" ], "corpus_id": 226153148, "doc_id": "226153148", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Propuesta de diseno de pilares de acero inoxidable sometidos a flexo compresion utilizando el Continuous Strengh Method", "venue": "", "year": 2020 }, { "abstract": "In the treatment of cervical pain, several techniques that are commonly used cannot indicate the patient painintensity, but only can identify structural damage. The evaluation of this pain intensity can be achieved analyzing the cervical joint kinematic variables of the three movements: flexo extension, flexo lateral and rotation. In this work we will study the reliability of the photogrammetry technique through a low cost camera, i.e. Kinect V1. The Kinect camera will acquire kinematic parameters of the flexo extension movement from the neck joint. We will use artificial vision and depth/color image techniques to obtaining the trajectories of the technical (and anatomical) markers. A Kalman filter is employed to correct the continuous tracking of the technical markers to obtaining the spatial coordinates of each marker. The data is obtained from seven test subjects, men and women physically healthy. The ages of the testsubjects are between 17 and 40 years. We compute the kinematic parameters of angular velocity, angular acceleration and angular displacement, associated with the spatial coordinates of each technical marker. Then, we obtain the parameters of reliability and correlation between tests through the mean standard error, the multiple correlation index and the Pearsoncorrelation indexes, commonly used for clinical analysis. The high values of these correlation indexes let us to remark the reliability of our methodology.", "author_names": [ "Kleber Vicente", "William Andres Garzon Venegas", "Christian Vasconez", "Ivan Zambrano" ], "corpus_id": 218825570, "doc_id": "218825570", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Analisis de Flexo extension del Cuello Mediante el Uso de Vision Artificial", "venue": "", "year": 2020 } ]

[ { "abstract": "Lead (Pb) halide perovskites have achieved great success in recent years because of their excellent optoelectronic properties, which is largely attributed to the lone pair s orbital derived antibonding states at the valence band edge. Guided by the key band edge orbital character, a series of ns2 containing (i.e. Sn2+ Sb3+ and Bi3+ Pb free perovskite alternatives have been explored as potential photovoltaic candidates. On the other hand, based on the band edge orbital components (i.e. M2+ s and p/X p orbitals) a series of strategies have been proposed to optimize their optoelectronic properties by modifying the atomic orbitals and orbital interactions. Therefore, understanding the band edge electronic features from the recently reported halide perovskites is essential for future material design and device optimization. This Perspective first attempts to establish the band edge orbital property relationship using a chemically intuitive approach and then rationalizes their superior properties and explains the trends in electronic properties. We hope that this Perspective will provide atomic level guidance and insights toward the rational design of perovskite semiconductors with outstanding optoelectronic properties.", "author_names": [ "Gang Tang", "Philippe Ghosez" ], "corpus_id": 232257686, "doc_id": "232257686", "n_citations": 5, "n_key_citations": 0, "score": 1, "title": "Band Edge Orbital Engineering of Perovskite Semiconductors for Optoelectronic Applications.", "venue": "The journal of physical chemistry letters", "year": 2021 }, { "abstract": "The effects of ferroic distortion and biaxial strain on the band gap and band edges of SrTiO(3) are calculated by using density functional theory and many body perturbation theory. Anisotropic strains are shown to reduce the gap by breaking degeneracies at the band edges. Ferroic distortions are shown to widen the gap by allowing new band edge orbital mixings. Compressive biaxial strains raise band edge energies, while tensile strains lower them. To reduce the SrTiO(3) gap, one must lower the symmetry from cubic while suppressing ferroic distortions. Our calculations indicate that, for engineered orientation of the growth direction along [111] the SrTiO(3) gap can be controllably and considerably reduced at room temperature.", "author_names": [ "Robert F Berger", "Craig J Fennie", "Jeffrey B Neaton" ], "corpus_id": 42036523, "doc_id": "42036523", "n_citations": 90, "n_key_citations": 1, "score": 0, "title": "Band gap and edge engineering via ferroic distortion and anisotropic strain: the case of SrTiO(3)", "venue": "Physical review letters", "year": 2011 }, { "abstract": "Abstract The effect of edge passivation with non metallic atoms was evaluated on some structural and electronic properties of MoS2 nanoribbons. It was observed that at Na 12 and above, the band gap is less oscillating and converges to 0.58 eV. By reducing the dimensionality, the band gap value changed dramatically. We found that d orbital of Mo atom greatly affects the density of states. All passivation processes were performed with H and X atoms, where X is a non metallic atom. The hybridization of p and s orbitals of X and Mo atoms plays an important role in changing the electronic properties of AMoS2NR. It was found that after passivation the largest band gap change is related to the most stable structure. Our studies suggest that the band gap of AMoS2NR H X depends on two factors: the nanoribbon width and the hybridization of Mo X orbitals.", "author_names": [ "Huang Jing" ], "corpus_id": 235557065, "doc_id": "235557065", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Increasing stability of MoS2 nanoribbons by edge engineering", "venue": "", "year": 2021 }, { "abstract": "Two dimensional electron dispersions with peculiar band crossings provide a platform for realizing topological phases of matter. Here we theoretically show that the eg orbital manifold of honeycomb layered transition metal compounds accommodates a plethora of peculiar band crossings, such as multiple Dirac point nodes, quadratic band crossings, and line nodes. From the tight binding analysis, we find that the band topology is systematically changed by the orbital dependent transfer integrals on the honeycomb network of edge sharing octahedra, which can be modulated by distortions of the octahedra as well as chemical substitutions. The band crossings are gapped out by the spin orbit coupling, which brings about a variety of topological phases distinguished by the spin Chern numbers. The results provide a comprehensive understanding of the previous studies on various honeycomb compounds. We also propose another candidate materials by ab initio calculations.", "author_names": [ "Yusuke Sugita", "Yukitoshi Motome" ], "corpus_id": 55483682, "doc_id": "55483682", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "M ay 2 01 8 Engineering of Band Crossings in Honeycomb layered Transition Metal Compounds", "venue": "", "year": 2018 }, { "abstract": "Two dimensional electron dispersions with peculiar band crossings provide a platform for realizing topological phases of matter. Here we theoretically show that the $e_g$ orbital manifold of honeycomb layered transition metal compounds accommodates a plethora of peculiar band crossings, such as multiple Dirac point nodes, quadratic band crossings, and line nodes. From the tight binding analysis, we find that the band topology is systematically changed by the orbital dependent transfer integrals on the honeycomb network of edge sharing octahedra, which can be modulated by distortions of the octahedra as well as chemical substitutions. The band crossings are gapped out by the spin orbit coupling, which brings about a variety of topological phases distinguished by the spin Chern numbers. The results provide a comprehensive understanding of the previous studies on various honeycomb compounds. We also propose another candidate materials by ab initio calculations.", "author_names": [ "Yusuke Sugita", "Yukitoshi Motome" ], "corpus_id": 125874643, "doc_id": "125874643", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Engineering of Band Crossings in Honeycomb layered Transition Metal Compounds", "venue": "", "year": 2018 }, { "abstract": "We calculate the band structure and the conductance of periodic edge corrugated graphene nanoribbons within the framework of the tight binding p orbital model. We consider corrugated structures based on host ribbons with armchair and zigzag edges and three different types of corrugations (armchair edges, zigzag edges, as well as a rectangular corrugation) We demonstrate that for armchair host ribbons, depending on the type of corrugation, a band gap or low velocity minibands appear near the charge neutrality point. For higher energies the allowed Bloch state bands become separated by ministopbands. By contrast, for corrugated ribbons with the zigzag host, the corrugations introduce neither band gaps nor stopbands (except for the case of the rectangular corrugations) The conductances of finite edge corrugated ribbons are analyzed on the basis of the corresponding band structures. For a sufficiently large number of corrugations the conductance follows the number of the corresponding propagating Bloch states and shows pronounced oscillations due to the Fabry Perot interference within the corrugated segments. Finally we demonstrate that edge disorder strongly affects the conductances of corrugated ribbons. Our results indicate that observation of miniband formation in corrugated ribbons would require clean, edge disorder free samples, especially for the case of the armchair host lattice.", "author_names": [ "S Ihnatsenka", "Igor V Zozoulenko", "George Kirczenow" ], "corpus_id": 55036139, "doc_id": "55036139", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Band gap engineering and ballistic transport in edge corrugated graphene nanoribbons", "venue": "", "year": 2009 }, { "abstract": "A series of trigonal planar N O and S dopant atoms incorporated along the convex protrusion lining the edges of bottom up synthesized chevron graphene nanoribbons (cGNRs) induce a characteristic shift in the energy of conduction and valence band edge states along with a significant reduction of the band gap of up to 0.3 eV per dopant atom per monomer. A combination of scanning probe spectroscopy and density functional theory calculations reveals that the direction and the magnitude of charge transfer between the dopant atoms and the cGNR backbone are dominated by inductive effects and follow the expected trend in electronegativity. The introduction of heteroatom dopants with trigonal planar geometry ensures an efficient overlap of a p orbital lone pair centered on the dopant atom with the extended p system of the cGNR backbone effectively extending the conjugation length. Our work demonstrates a widely tunable method for band gap engineering of graphene nanostructures for advanced electronic applications.", "author_names": [ "Rebecca A Durr", "Danny Haberer", "Yea-Lee Lee", "Raymond Blackwell", "Alin Miksi Kalayjian", "Tomas Marangoni", "Jisoon Ihm", "Steven G Louie", "Felix R Fischer" ], "corpus_id": 207188058, "doc_id": "207188058", "n_citations": 39, "n_key_citations": 0, "score": 0, "title": "Orbitally Matched Edge Doping in Graphene Nanoribbons.", "venue": "Journal of the American Chemical Society", "year": 2018 }, { "abstract": "The effects of in plane biaxial strain on the electronic structure of a photofunctional material, single layer SnS2, were systematically investigated using hybrid density functional calculations. The bonding diagram for the band gap was firstly proposed based on the crystal orbital overlap population analysis. The conduction band edge of single layer SnS2 is determined by the anti bonding interaction between Sn 5s and S 3p orbitals, while the valence band edge comes from the anti bonding between the neighboring S atoms. It is found that the compressive strain not only decreases the indirect band gap of single layer SnS2, but also effectively promotes the band edges of the conduction band to realize the overall water splitting. Besides, the dispersion of the valence band of single layer SnS2 becomes weaker with increasing tensile strain which is beneficial for the photo excitation through direct transitions.", "author_names": [ "Wei Zhou", "Naoto Umezawa" ], "corpus_id": 42115808, "doc_id": "42115808", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Insight into the band structure engineering of single layer SnS2 with in plane biaxial strain.", "venue": "Physical chemistry chemical physics PCCP", "year": 2016 }, { "abstract": "PdCl3 belongs to a novel class of Dirac materials with Dirac spin gapless semiconducting characteristics. In this paper based, on first principles calculations, we have systematically investigated the effect of adatom adsorption, vacancy defects, electric field, strain, edge states and layer thickness on the electronic and magnetic properties of PdCl3 (palladium trichloride) Our results show that when spin orbital coupling is included, PdCl3 exhibits the quantum anomalous Hall effect with a non trivial band gap of 24 meV. With increasing number of layers, from monolayer to bulk, a transition occurs from a Dirac half metal to a ferromagnetic metal. On application of a perpendicular electrical field to bilayer PdCl3, we find that the energy band gap decreases with increasing field. Uniaxial and biaxial strain, significantly modifies the electronic structure depending on the strain type and magnitude. Adsorption of adatom and topological defects have a dramatic effect on the electronic and magnetic properties of PdCl3. In particular, the structure can become a metal (Na) half metal (Be, Ca, Al, Ti, V, Cr, Fe and Cu with, respective, 0.72, 9.71, 7.14, 6.90, 9.71, 4.33 and 9.5 mB magnetic moments) ferromagnetic metal (Sc, Mn and Co with 4.55, 7.93 and 2.0 mB) spin glass semiconductor (Mg, Ni with 3.30 and 8.63 mB) and dilute magnetic semiconductor (Li, K and Zn with 9.0, 9.0 and 5.80 mB magnetic moment, respectively) Single Pd and double Pd Cl vacancies in PdCl3 display dilute magnetic semiconductor characteristics, while with a single Cl vacancy, the material becomes a half metal. The calculated optical properties of PdCl3 suggest it could be a good candidate for microelectronic and optoelectronics devices.", "author_names": [ "Asadollah Bafekry", "Catherine Stampfl", "Francois M Peeters" ], "corpus_id": 210169153, "doc_id": "210169153", "n_citations": 19, "n_key_citations": 0, "score": 0, "title": "Dirac half metallicity of Thin PdCl3 Nanosheets: Investigation of the Effects of External Fields, Surface Adsorption and Defect Engineering on the Electronic and Magnetic Properties", "venue": "Scientific Reports", "year": 2020 }, { "abstract": "Density functional theory calculations were carried out for Ni1 xMgxO alloys using both GGA+U method and hybrid exchange correlation functional HSE06. We find that the band gap of Ni1 xMgxO is a nonlinear function of MgO concentration with a strong bowing behavior at high Mg content. Band edge alignment is determined using heterojunction superlattice models. The valence band maximum of Ni1 xMgxO is shown to be tunable within a range of 0.90 eV. By comparing with the highest occupied molecular orbital levels of some of the most widely used dye molecules, we propose that Ni1 xMgxO is a promising alternate to replace NiO photocathode in dye sensitized solar cells with an enhanced open circuit voltage and transparency of cathode films.", "author_names": [ "Junkai Deng", "Majid Mortazavi", "Nikhil V Medhekar", "Jefferson Z Liu" ], "corpus_id": 120027600, "doc_id": "120027600", "n_citations": 23, "n_key_citations": 1, "score": 0, "title": "Band engineering of Ni1 xMgxO alloys for photocathodes of high efficiency dye sensitized solar cells", "venue": "", "year": 2012 } ]

[ { "abstract": "Anisotropic carrier transport properties of unintentionally doped InAs/InAs0.65Sb0.35 type II strain balanced superlattice material are evaluated using temperature and field dependent magnetotransport measurements performed in the vertical direction on a substrate removed metal semiconductor metal device structure. To best isolate the measured transport to the superlattice, device fabrication entails flip chip bonding and backside device processing to remove the substrate material and deposit contact metal directly to the bottom of an etched mesa. High resolution mobility spectrum analysis is used to calculate the conductance contribution and corrected mixed vertical lateral mobility of the two carrier species present. Combining the latter with lateral mobility results from in plane magnetotransport measurements on identical superlattice material allows for the calculation of the true vertical majority electron and minority hole mobilities; amplitudes of 4.7 x 10 3 cm2/V s and 1.60 cm2/V s are determined at 77 K, respectively. The temperature dependent results show that vertical hole mobility rapidly decreases with decreasing temperature due to trap induced localization and then hopping transport, whereas vertical electron mobility appears phonon scattering limited at high temperature, giving way to interface roughness scattering at low temperatures, analogous to the lateral electron mobility but with a lower overall magnitude.", "author_names": [ "Lilian K Casias", "Christian P Morath", "Elizabeth H Steenbergen", "Gilberto A Umana-Membreno", "Preston T Webster", "Julie V Logan", "Jin Young Kim", "Ganesh Balakrishnan", "Lorenzo Faraone", "Sanjay Krishna" ], "corpus_id": 218919207, "doc_id": "218919207", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Vertical carrier transport in strain balanced InAs/InAsSb type II superlattice material", "venue": "", "year": 2020 }, { "abstract": "Abstract In this paper, we report on the demonstration of a midwave infrared (MWIR) Ga free InAs/InAsSb superlattice (SL) barrier detector, grown monolithically on a Si substrate by molecular beam epitaxy (MBE) Prior to the use of MBE, the (1 0 0) Si substrate was prepared in situ in a metal organic chemical vapor deposition (MOCVD) reactor, where an 800 nm thick GaSb buffer layer was grown. Next, a barrier structure with an active zone made of strain balanced InAs/InAsSb SL, lattice matched to GaSb, was epitaxied. Structural characterisations revealed that the material quality was degraded compared with the sample grown on GaSb. The processed Ga free SL barrier detector has a 100% cut off wavelength of 5 um at 150 K, for a bias operation of 500 mV. A combined analysis involving electrical and electro optical characterisation was performed to identify the operating regimes in this MWIR Ga free SL barrier structure.", "author_names": [ "Quentin Durlin", "J P Perez", "Laurent Cerutti", "Jean-Baptiste Rodriguez", "Tiphaine Cerba", "Thierry Baron", "Eric Tournie", "Philippe Christol" ], "corpus_id": 125102311, "doc_id": "125102311", "n_citations": 23, "n_key_citations": 0, "score": 1, "title": "Midwave infrared barrier detector based on Ga free InAs/InAsSb type II superlattice grown by molecular beam epitaxy on Si substrate", "venue": "", "year": 2019 }, { "abstract": "We report focal plane array (FPA) results on a mid wavelength InAs/InAsSb type II strained layer superlattice (T2SLS) unipolar barrier infrared detector with a cutoff wavelength of 5.4 mm. For 300 K background in the 3 5 mm band, f/2 aperture, an FPA operating at 150 K exhibits a mean noise equivalent differential temperature (NEDT) of 18.5 mK, and an NEDT operability of 99.7% The NEDT distribution has a width of 8 mK, with no noticeable distribution tail, indicating excellent uniformity. The mean noise equivalent irradiance is 9.1 x 10¹¹ photons/sec cm² The mean quantum efficiency is 49.1% without antireflection coating, and the mean specific detectivity (D<sup>/sup> is 2.53 x 10¹¹ cm Hz<sup> 1/2 /sup>/W. Benefitting from an absorber material with a much longer Shockley Read Hall minority carrier lifetime, and a device architecture that suppresses generation recombination and surface leakage dark current, the InAs/InAsSb T2SLS barrier infrared detector FPA has demonstrated a significantly higher operating temperature than the mid wavelength infrared market leading InSb.", "author_names": [ "David Z Ting", "Sir Rafol", "Sam Keo", "Jean Nguyen", "Arezou Khoshakhlagh", "Alexander Soibel", "Linda Hoglund", "Anita Fisher", "Edward Luong", "Jason Mumolo", "John K Liu", "Sarath D Gunapala" ], "corpus_id": 53428442, "doc_id": "53428442", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "InAs/InAsSb Type II Superlattice Mid Wavelength Infrared Focal Plane Array With Significantly Higher Operating Temperature Than InSb", "venue": "IEEE Photonics Journal", "year": 2018 }, { "abstract": "Abstract By introducing a double barrier design, a high performance InAs/InAsSb type II superlattice mid wavelength infrared photodetector has been demonstrated. The photodetector exhibits a cut off wavelength of ~4.50 um at 150 K. At 150 K and 120 mV applied bias, the photodetector exhibits a dark current density of 1.21 x 10 5 A/cm2, a quantum efficiency of 45% at peak responsivity ~3.95 um) and a specific detectivity of 6.9 x 1011 cm*Hz1/2/W. The photodetector shows background limited operating temperature up to 160 K.", "author_names": [ "Donghai Wu", "Jiakai Li", "Arash Dehzangi", "Manijeh Razeghi" ], "corpus_id": 225329948, "doc_id": "225329948", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "High performance InAs/InAsSb Type II superlattice mid wavelength infrared photodetectors with double barrier", "venue": "", "year": 2020 }, { "abstract": "The InAs/InAsSb (Gallium free) type II strained layer superlattice (T2SLS) has emerged in the last decade as a viable infrared detector material with a continuously adjustable band gap capable of accommodating detector cutoff wavelengths ranging from 4 to 15 um and beyond. When coupled with the unipolar barrier infrared detector architecture, the InAs/InAsSb T2SLS mid wavelength infrared (MWIR) focal plane array (FPA) has demonstrated a significantly higher operating temperature than InSb FPA, a major incumbent technology. In this brief review paper, we describe the emergence of the InAs/InAsSb T2SLS infrared photodetector technology, point out its advantages and disadvantages, and survey its recent development.", "author_names": [ "David Z Ting", "Sir Rafol", "Arezou Khoshakhlagh", "Alexander Soibel", "Sam Keo", "Anita Fisher", "Brian Pepper", "Cory Hill", "Sarath D Gunapala" ], "corpus_id": 226082203, "doc_id": "226082203", "n_citations": 6, "n_key_citations": 1, "score": 0, "title": "InAs/InAsSb Type II Strained Layer Superlattice Infrared Photodetectors", "venue": "Micromachines", "year": 2020 }, { "abstract": "Abstract The InAs/InAs1 xSbx type II superlattices (T2SLs) grown on GaSb buffer layer and GaAs substrates have recently been applied for detectors for long wavelength infrared (LWIR) range and high operating temperature (HOT) conditions. The detailed modeling of T2SLs minibands structure required for detector's design optimization process relies on accurate knowledge of the InAs1 xSbx bandgap and band edge position. The kp (8 x 8 method) was used to analyze the valence band offset (VBO) between InAs and InAs1 xSbx, and hence the InAs1 xSbx band edge position at required xSb composition. An increase of the VBO leads to the structure transformation from type IIb to type II superlattices. The required energy bandgap can be reached by changing the conduction band offset (CBO) and the energy bandgap bowing parameter. The temperature dependence of the experimental results of InAs/InAs1 xSbx T2SLs energy bandgap was found to be comparable with theoretical one when energy bandgap bowing parameter is dependent on temperature. The proper fitting of theoretically calculated and experimentally measured spectral response characteristics was shown.", "author_names": [ "Tetiana Manyk", "Krystian Michalczewski", "Krzysztof Murawski", "Kacper Grodecki", "Jaroslaw Rutkowski", "Piotr Martyniuk" ], "corpus_id": 139986049, "doc_id": "139986049", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Electronic band structure of InAs/InAsSb type II superlattice for HOT LWIR detectors", "venue": "", "year": 2018 }, { "abstract": "Optical and structural properties of InAs/InAsSb type II superlattices (T2SL) and their feasibility for mid and longwavelength infrared (MWIR and LWIR) photodetector applications are investigated. The InAs/InAsSb T2SL structures with a broad bandgap range covering 4 mm to 12 mm are grown by molecular beam epitaxy and characterized by highresolution x ray diffraction and photoluminescence (PL) spectroscopy. All of the samples have excellent structural properties and strong PL signal intensities of the same order of magnitude, indicating that non radiative recombination is not dominant and the material system is promising for high performance MWIR and LWIR detectors and multiband FPAs.", "author_names": [ "Oray Orkun Cellek", "Hua Li", "Xiao-Meng Shen", "Zhiyuan Lin", "Elizabeth H Steenbergen", "D W Ding", "Shi Liu", "Qiang Zhang", "Ha sul Kim", "Jin Fan", "Michael J DiNezza", "W Hank G Dettlaff", "Preston T Webster", "Zhao-Yu He", "Jing-Jing Li", "Shane R Johnson", "David John Smith", "Yong-Hang Zhang" ], "corpus_id": 122751284, "doc_id": "122751284", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "InAs/InAsSb Type II superlattice: a promising material for mid wavelength and long wavelength infrared applications", "venue": "Defense Commercial Sensing", "year": 2012 }, { "abstract": "We recently reported mid wavelength infrared (MWIR) InAs/InAsSb type II strained layer superlattice (T2SLS) unipolar barrier detectors and focal plane arrays with significantly higher operating temperature than InSb. Herein, we document the development leading to the MWIR InAs/InAsSb T2SLS detectors at the NASA Jet Propulsion Laboratory. We also briefly compare the InAs/InAsSb T2SLS with some other approaches.", "author_names": [ "David Z Ting", "Alexander Soibel", "Arezou Khoshakhlagh", "Sam Keo", "Sir Rafol", "Linda Hoglund", "Edward Luong", "Anita Fisher", "Cory Hill", "Sarath D Gunapala" ], "corpus_id": 155305808, "doc_id": "155305808", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Development of InAs/InAsSb Type II Strained Layer Superlattice Unipolar Barrier Infrared Detectors", "venue": "Journal of Electronic Materials", "year": 2019 }, { "abstract": "The InAs/InAsSb (Gallium free) type II strained layer superlattice (T2SLS) is an adjustable band gap, broad band III V infrared detector material that has emerged in recent years as an alternative to the more established InAs/GaSb type II superlattice. We have reported results on a mid wavelength focal plane array (FPA) based on the InAs/InAsSb T2SLS unipolar barrier infrared detector architecture. Significantly, the FPA exhibits very good operating characteristics at 160 K, demonstrating a considerably operating temperature advantage over the MWIR market leading InSb FPAs, while maintaining III V semiconductor manufacturing robustness. In this article we summarize the development at the NASA Jet Propulsion Laboratory leading to the mid wavelength InAs/InAsSb T2SLS infrared detectors, provide a brief look at the history of the development of the InAs/InAsSb T2SLS absorber, and survey the current status of InAs/InAsSb T2SLS detectors.", "author_names": [ "David Z Ting", "Alexander Soibel", "Arezou Khoshakhlagh", "Sam Keo", "Sir Rafol", "Anita Fisher", "Cory Hill", "Edward Luong", "Brian Pepper", "Sarath D Gunapala" ], "corpus_id": 181737520, "doc_id": "181737520", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "The emergence of InAs/InAsSb type II strained layer superlattice barrier infrared detectors", "venue": "Defense Commercial Sensing", "year": 2019 }, { "abstract": "We studied Ga free InAs/InAsSb type II superlattice (T2SL) in terms of period, thickness and antimony composition as a photon absorbing active layer (AL) of a suitable XBn structure for full mid wavelength infrared domain (MWIR, 3 5mm) detection. The SL photodetector structures were fabricated by molecular beam epitaxy (MBE) on n type GaSb substrate and exhibited cut off wavelength between 5mm and 5.5mm at 150K. Electro optical and electrical results of the device are reported and compared to the usual InSb MWIR photodiode.", "author_names": [ "J P Perez", "Quentin Durlin", "Philippe Christol" ], "corpus_id": 199827082, "doc_id": "199827082", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Ga free InAs/InAsSb type II superlattice (T2SL) photodetector for high operating temperature in the midwave infrared spectral domain", "venue": "International Conference on Space Optics", "year": 2019 } ]

[ { "abstract": "Unlike graphene, the existence of bandgaps (1 2 eV) in the layered semiconductor molybdenum disulphide, combined with mobility enhancement by dielectric engineering, offers an attractive possibility of using single layer molybdenum disulphide field effect transistors in low power switching devices. However, the complicated process of fabricating single layer molybdenum disulphide with an additional high k dielectric layer may significantly limit its compatibility with commercial fabrication. Here we show the first comprehensive investigation of process friendly multilayer molybdenum disulphide field effect transistors to demonstrate a compelling case for their applications in thin film transistors. Our multilayer molybdenum disulphide field effect transistors exhibited high mobilities >100 cm(2) V( 1) s( 1) near ideal subthreshold swings ~70 mV per decade) and robust current saturation over a large voltage window. With simulations based on Shockley's long channel transistor model and calculations of scattering mechanisms, these results provide potentially important implications in the fabrication of high resolution large area displays and further scientific investigation of various physical properties expected in other layered semiconductors.", "author_names": [ "Sunkook Kim", "Aniruddha Konar", "Wan Sik Hwang", "Jong Hak Lee", "Jiyoul Lee", "Jae-Hak Yang", "Changhoon Jung", "Hyoungsub Kim", "Ji-Beom Yoo", "Jaeyoung Choi", "Yong Wan Jin", "Sang Yoon Lee", "Debdeep Jena", "Woong Choi", "Kinam Kim" ], "corpus_id": 2926396, "doc_id": "2926396", "n_citations": 1221, "n_key_citations": 16, "score": 1, "title": "High mobility and low power thin film transistors based on multilayer MoS2 crystals.", "venue": "Nature communications", "year": 2012 }, { "abstract": "We present the Spectroscopic Imaging survey in the near infrared (near IR) with SINFONI (SINS) of high redshift galaxies. With 80 objects observed and 63 detected in at least one rest frame optical nebular emission line, mainly Ha, SINS represents the largest survey of spatially resolved gas kinematics, morphologies, and physical properties of star forming galaxies at z 1 3. We describe the selection of the targets, the observations, and the data reduction. We then focus on the \"SINS Ha sample,\" consisting of 62 rest UV/optically selected sources at 1.3 z 2.6 for which we targeted primarily the Ha and [N II] emission lines. Only 30% of this sample had previous near IR spectroscopic observations. The galaxies were drawn from various imaging surveys with different photometric criteria; as a whole, the SINS Ha sample covers a reasonable representation of massive M_* 10^(10) M_ star forming galaxies at z 1.5 2.5, with some bias toward bluer systems compared to pure K selected samples due to the requirement of secure optical redshift. The sample spans 2 orders of magnitude in stellar mass and in absolute and specific star formation rates, with median values 3 x 10^(10) M_, 70 M_ yr^ 1) and 3 Gyr^ 1) The ionized gas distribution and kinematics are spatially resolved on scales ranging from 1.5 kpc for adaptive optics assisted observations to typically 4 5 kpc for seeing limited data. The Ha morphologies tend to be irregular and/or clumpy. About one third of the SINS Ha sample galaxies are rotation dominated yet turbulent disks, another one third comprises compact and velocity dispersion dominated objects, and the remaining galaxies are clear interacting/merging systems; the fraction of rotation dominated systems increases among the more massive part of the sample. The Ha luminosities and equivalent widths suggest on average roughly twice higher dust attenuation toward the H II regions relative to the bulk of the stars, and comparable current and past averaged star formation rates.", "author_names": [ "Natascha M Forster Schreiber", "Reinhard Genzel", "Nicolas F Bouche", "Giovanni Cresci", "Rodney D Davies", "Peter Buschkamp", "Kristen Leah Shapiro", "Linda J Tacconi", "E K S Hicks", "Shy Genel", "Alice E Shapley", "Dawn K Erb", "Charles C Steidel", "Dieter Lutz", "Frank Eisenhauer", "Stefan Gillessen", "Amiel Sternberg", "Alvio Renzini", "Andrea Cimatti", "Emanuele Daddi", "Jaron Daniel Kurk", "Simon J Lilly", "Xu Kong", "Matthew D Lehnert", "Nicole P H Nesvadba", "Aprajita Verma", "H J Mccracken", "Nobuo Arimoto", "Marco Mignoli", "Masato Onodera" ], "corpus_id": 17159511, "doc_id": "17159511", "n_citations": 826, "n_key_citations": 317, "score": 0, "title": "THE SINS SURVEY: SINFONI INTEGRAL FIELD SPECTROSCOPY OF z 2 STAR FORMING GALAXIES*", "venue": "", "year": 2009 }, { "abstract": "Connecting caldera collapse The Kilauea Volcano on the island of Hawai'i erupted for 3 months in 2018. Neal et al. present a summary of the eruption sequence along with a variety of geophysical observations collected by the Hawaiian Volcano Observatory. The cyclic inflation, deflation, and eventual collapse of the summit was tied to lava eruption from lower East Rift Zone fissures. A total volume of 0.8 cubic kilometers of magma erupted, roughly the equivalent of 320,000 swimming pools, which matched the change in volume at the summit. Science, this issue p. 367 The Kilauea Volcano erupted 0.8 cubic kilometers of magma, which triggered a summit collapse over the 3 months of the eruption. In 2018, Kilauea Volcano experienced its largest lower East Rift Zone (LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu'u 'O'o vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending ~6.8 kilometers. A 4 May earthquake [moment magnitude (Mw) 6.9] produced ~5 meters of fault slip. Lava erupted at rates exceeding 100 cubic meters per second, eventually covering 35.5 square kilometers. The summit magma system partially drained, producing minor explosions and near daily collapses releasing energy equivalent to Mw 4.7 to 5.4 earthquakes. Activity declined rapidly on 4 August. Summit collapse and lava flow volume estimates are roughly equivalent about 0.8 cubic kilometers. Careful historical observation and monitoring of Kilauea enabled successful forecasting of hazardous events.", "author_names": [ "C A Neal", "S R Brantley", "L Antolik", "Janet Lynn Babb", "M Burgess", "Kaitlian Calles", "M Cappos", "J C Chang", "S Conway", "L Desmither", "P Dotray", "T Elias", "P Fukunaga", "Steven Fuke", "Ingrid A Johanson", "K Kamibayashi", "J P Kauahikaua", "R Lopaka Lee", "S Pekalib", "Asta Miklius", "W Million", "C J Moniz", "Patricia Amanda Nadeau", "Paul G Okubo", "Carolyn Parcheta", "Matthew R Patrick", "Brian R Shiro", "Donald A Swanson", "W Tollett", "Frank A Trusdell", "Edward F Younger", "Michael Zoeller", "E K Montgomery-Brown", "Kyle Anderson", "Michael P Poland", "J L Ball", "J Bard", "Michelle L Coombs", "Hannah R Dietterich", "Christoph Kern", "Weston A Thelen", "P F Cervelli", "Tim R Orr", "Bruce F Houghton", "Cheryl Gansecki", "Richard W Hazlett", "Paul R Lundgren", "Angela Diefenbach", "Allan H Lerner", "Gregory P Waite", "Peter Kelly", "L Clor", "C Werner", "K Mulliken", "G Fisher", "David E Damby" ], "corpus_id": 54479549, "doc_id": "54479549", "n_citations": 188, "n_key_citations": 7, "score": 0, "title": "The 2018 rift eruption and summit collapse of Kilauea Volcano", "venue": "Science", "year": 2019 }, { "abstract": "The resistivity of ultraclean suspended graphene is strongly temperature (T) dependent for 5<T<240 K. At T 5 K transport is near ballistic in a device of approximately 2 microm dimension and a mobility approximately 170,000 cm2/V s. At large carrier density, n>0.5 x 10(11) cm( 2) the resistivity increases with increasing T and is linear above 50 K, suggesting carrier scattering from acoustic phonons. At T=240 K the mobility is approximately 120,000 cm2/V s, higher than in any known semiconductor. At the charge neutral point we observe a nonuniversal conductivity that decreases with decreasing T, consistent with a density inhomogeneity <10(8) cm( 2)", "author_names": [ "Kirill I Bolotin", "K J Sikes", "James C Hone", "Horst L Stormer", "Philip Kim" ], "corpus_id": 12252566, "doc_id": "12252566", "n_citations": 903, "n_key_citations": 17, "score": 0, "title": "Temperature dependent transport in suspended graphene.", "venue": "Physical review letters", "year": 2008 }, { "abstract": "It is well known that for many NP complete problems, such as K Sat, etc. typical cases are easy to solve; so that computationally hard cases must be rare (assuming P NP) This paper shows that NP complete problems can be summarized by at least one \"order parameter\" and that the hard problems occur at a critical value of such a parameter. This critical value separates two regions of characteristically different properties. For example, for K colorability, the critical value separates overconstrained from underconstrained random graphs, and it marks the value at which the probability of a solution changes abruptly from near 0 to near 1. It is the high density of well separated almost solutions (local minima) at this boundary that cause search algorithms to \"thrash\" This boundary is a type of phase transition and we show that it is preserved under mappings between problems. We show that for some P problems either there is no phase transition or it occurs for bounded N (and so bounds the cost) These results suggest a way of deciding if a problem is in P or NP and why they are different.", "author_names": [ "Peter C Cheeseman", "Bob Kanefsky", "William Taylor" ], "corpus_id": 6634061, "doc_id": "6634061", "n_citations": 1307, "n_key_citations": 74, "score": 0, "title": "Where the Really Hard Problems Are", "venue": "IJCAI", "year": 1991 }, { "abstract": "Summary Background Endometriosis is a risk factor for epithelial ovarian cancer; however, whether this risk extends to all invasive histological subtypes or borderline tumours is not clear. We undertook an international collaborative study to assess the association between endometriosis and histological subtypes of ovarian cancer. Methods Data from 13 ovarian cancer case control studies, which were part of the Ovarian Cancer Association Consortium, were pooled and logistic regression analyses were undertaken to assess the association between self reported endometriosis and risk of ovarian cancer. Analyses of invasive cases were done with respect to histological subtypes, grade, and stage, and analyses of borderline tumours by histological subtype. Age, ethnic origin, study site, parity, and duration of oral contraceptive use were included in all analytical models. Findings 13 226 controls and 7911 women with invasive ovarian cancer were included in this analysis. 818 and 738, respectively, reported a history of endometriosis. 1907 women with borderline ovarian cancer were also included in the analysis, and 168 of these reported a history of endometriosis. Self reported endometriosis was associated with a significantly increased risk of clear cell (136 [20*2% of 674 cases vs 818 [6*2% of 13 226 controls, odds ratio 3*05, 95% CI 2*43 3*84, p<0*0001) low grade serous (31 [9*2% of 336 cases, 2*11, 1*39 3*20, p<0*0001) and endometrioid invasive ovarian cancers (169 [13*9% of 1220 cases, 2*04, 1*67 2*48, p<0*0001) No association was noted between endometriosis and risk of mucinous (31 [6*0% of 516 cases, 1*02, 0*69 1*50, p=0*93) or high grade serous invasive ovarian cancer (261 [7*1% of 3659 cases, 1*13, 0*97 1*32, p=0*13) or borderline tumours of either subtype (serous 103 [9*0% of 1140 cases, 1*20, 0*95 1*52, p=0*12, and mucinous 65 [8*5% of 767 cases, 1*12, 0*84 1*48, p=0*45) Interpretation Clinicians should be aware of the increased risk of specific subtypes of ovarian cancer in women with endometriosis. Future efforts should focus on understanding the mechanisms that might lead to malignant transformation of endometriosis so as to help identify subsets of women at increased risk of ovarian cancer. Funding Ovarian Cancer Research Fund, National Institutes of Health, California Cancer Research Program, California Department of Health Services, Lon V Smith Foundation, European Community's Seventh Framework Programme, German Federal Ministry of Education and Research of Germany, Programme of Clinical Biomedical Research, German Cancer Research Centre, Eve Appeal, Oak Foundation, UK National Institute of Health Research, National Health and Medical Research Council of Australia, US Army Medical Research and Materiel Command, Cancer Council Tasmania, Cancer Foundation of Western Australia, Mermaid 1, Danish Cancer Society, and Roswell Park Alliance Foundation.", "author_names": [ "Celeste Leigh Pearce", "Claire Templeman", "Mary Anne Rossing", "Alice W Lee", "Aimee M Near", "Penelope M Webb", "Christina M Nagle", "Jennifer Anne Doherty", "Kara L Cushing-Haugen", "Kristine G Wicklund", "Jenny Chang-Claude", "Rebecca Hein", "Galina Lurie", "Lynne Wilkens", "Michael E Carney", "Marc T Goodman", "Kirsten B Moysich", "Susanne K Kjaer", "Estrid V Hogdall", "Allan Jensen", "Ellen L Goode", "Brooke L Fridley", "Melissa C Larson", "Joellen M Schildkraut", "Rachel T Palmieri", "Daniel W Cramer", "Kathryn L Terry", "Allison F Vitonis", "Linda J Titus", "Argyrios Ziogas", "Wendy R Brewster", "Hoda Anton-Culver", "Alex Gentry-Maharaj", "Susan J Ramus", "A Rebecca Anderson", "Doerthe Brueggmann", "Peter Andreas Fasching", "Simon A Gayther", "David G Huntsman", "Usha Menon", "Roberta B Ness", "Malcolm C Pike", "Harvey A Risch", "Anna H Wu", "Andrew Berchuck" ], "corpus_id": 12548132, "doc_id": "12548132", "n_citations": 663, "n_key_citations": 31, "score": 0, "title": "Association between endometriosis and risk of histological subtypes of ovarian cancer: a pooled analysis of case control studies", "venue": "The Lancet. Oncology", "year": 2012 }, { "abstract": "This paper introduces k' means algorithm that performs correct clustering without pre assigning the exact number of clusters. This is achieved by minimizing a suggested cost function. The cost function extends the mean square error cost function of k means. The algorithm consists of two separate steps. The first is a pre processing procedure that performs initial clustering and assigns at least one seed point to each cluster. During the second step, the seed points are adjusted to minimize the cost function. The algorithm automatically penalizes any possible winning chances for all rival seed points in subsequent iterations. When the cost function reaches a global minimum, the correct number of clusters is determined and the remaining seed points are located near the centres of actual clusters. The simulated experiments described in this paper confirm good performance of the proposed algorithm.", "author_names": [ "Krista Rizman alik" ], "corpus_id": 122574776, "doc_id": "122574776", "n_citations": 436, "n_key_citations": 27, "score": 0, "title": "An efficient k' means clustering algorithm", "venue": "", "year": 2008 }, { "abstract": "Introduction: In the era of multidrug resistant, extensively drug resistant (XDR) and even pandrug resistant Gram negative microorganisms, the medical community is facing the threat of untreatable infections particularly those caused by carbapenemase producing bacteria, that is, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii. Therefore, all the presently available antibiotics, as well as for the near future compounds, are presented and discussed. Areas covered: Current knowledge concerning mechanisms of action, in vitro activity and interactions, pharmacokinetic/pharmacodynamics, clinical efficacy and toxicity issues for revived and novel antimicrobial agents overcoming current resistance mechanisms, including colistin, tigecycline, fosfomycin, temocillin, carbapenems, and antibiotics still under development for the near future such as plazomicin, eravacycline and carbapenemase inhibitors is discussed. Expert opinion: Colistin is active in vitro and effective in vivo against XDR carbapenemase producing microorganisms in the critically ill host, whereas tigecycline, with the exception of P. aeruginosa, has a similar spectrum of activity. The efficacy of combination therapy in bacteremias and ventilator associated pneumonia caused by K. pneumoniae carbapenemase producers seems to be obligatory, whereas in cases of P. aeruginosa and A. baumannii its efficacy is questionable. Fosfomycin, which is active against P. aeruginosa and K. pneumoniae, although promising, shares poor experience in XDR infections. The in vivo validity of the newer potent compounds still necessitates the evaluation of Phase III clinical trials particularly in XDR infections.", "author_names": [ "Ilias Karaiskos", "Helen Giamarellou" ], "corpus_id": 33293578, "doc_id": "33293578", "n_citations": 213, "n_key_citations": 7, "score": 0, "title": "Multidrug resistant and extensively drug resistant Gram negative pathogens: current and emerging therapeutic approaches", "venue": "Expert opinion on pharmacotherapy", "year": 2014 }, { "abstract": "Granitic rhyolitic liquids were produced experimentally from moderately hydrous (1.7 2.3 wt% H2O) medium to high K basaltic compositions at 700 MPa and fO2 controlled from Ni NiO 1.3 to +4. Amount and composition of evolved liquids and coexisting mineral assemblages vary with fO2 and temperature, with melt being more evolved at higher fO2s, where coexisting mineral assemblages are more plagioclase and Fe Ti oxide rich and amphibole poor. At fO2 of Ni NiO +1, typical for many silicic magmas, the samples produce 12 25 wt% granitic rhyolitic liquid, amounts varying with bulk composition. Medium to high K basalts are common in subduction related magmatic arcs, and near solidus true granite or rhyolite liquids can form widely, and in geologically significant quantities, by advanced crystallization differentiation or by low degree partial remelting of mantle derived basaltic sources. Previously differentiated or weathered materials may be involved in generating specific felsic magmas, but are not required for such magmas to be voluminous or to have the K rich granitic compositions typical of the upper continental crust.", "author_names": [ "Thomas W Sisson", "Kent Ratajeski", "W Ben Hankins", "Allen F Glazner" ], "corpus_id": 140725886, "doc_id": "140725886", "n_citations": 729, "n_key_citations": 51, "score": 0, "title": "Voluminous granitic magmas from common basaltic sources", "venue": "", "year": 2005 }, { "abstract": "Photoelectronic responses of organic inorganic hybrid perovskite CH3NH3PbI3 on mesoporous TiO2 electrodes are investigated. On the basis of near band edge optical absorption and photoluminescence spectra, the bandgap energy and exciton binding energy as a function of temperature are obtained. The exciton binding energy is much smaller than thermal energy at room temperature, which means that most excitons are thermally dissociated, and optical processes are determined by the photoexcited electrons and holes. We determined the temperature dependence of exciton binding energy, which changes from ~30 meV at 13 K to 6 meV at 300 K. In addition, the bandgap energy and the exciton binding energy show abrupt changes at 150 K due to structural phase transition. Our fundamental optical studies provide essential information for improving the device performance of solar cells based on halide perovskite semiconductors.", "author_names": [ "Yasuhiro Yamada", "Toru Nakamura", "Masaru Endo", "Atsushi Wakamiya", "Yoshihiko Kanemitsu" ], "corpus_id": 24100924, "doc_id": "24100924", "n_citations": 129, "n_key_citations": 1, "score": 0, "title": "Photoelectronic Responses in Solution Processed Perovskite CH$_{\\bf 3} NH$_{\\bf 3}$PbI $_{\\bf 3} Solar Cells Studied by Photoluminescence and Photoabsorption Spectroscopy", "venue": "IEEE Journal of Photovoltaics", "year": 2015 } ]

[ { "abstract": "Co3O4 is a promising p type semiconductor for ethanol detection. In this work, ethanol detection sensors were fabricated with nanostructured Co3O4, which exhibited higher selectivity and lower operating temperature. The Co3O4 was synthesised using ZIF 67 as a sacrificial precursor. The T400 Co3O4 that was obtained by calcining ZIF 67 at 400 degC showed the best sensing performance. Its response to 100 ppm ethanol vapor was 221.99 at a low optimal operating temperature (200 degC) Moreover, T400 Co3O4 achieved a low detection limit (1 ppm) remarkable repeatability, and higher selectivity compared to ammonia, carbon monoxide, acetone, hydrogen, methane, methanol, and nitrogen dioxide. The enhanced sensing performance was mainly attributed to three factors: (1) the adsorption/desorption of active adsorbed oxygen molecules (e.g. O and O2 and abundant oxygen vacancies, which increased the number of active sites; (2) the catalytic activity of Co3+ which greatly increased the reaction route and decreased the activation energy; and (3) the effective diffusion of gas molecules, which increased the effect of collisions between gas molecules and the material surface. This work provides an effective means to fabricate sensitive ethanol gas sensors with low energy consumption.", "author_names": [ "Xiao Hang Zhang", "Yaohua Xu", "Hao Liu", "Wenru Zhao", "Anjie Ming", "Fengwei Wei" ], "corpus_id": 214266635, "doc_id": "214266635", "n_citations": 4, "n_key_citations": 0, "score": 1, "title": "Preparation of porous Co3O4 and its response to ethanol with low energy consumption", "venue": "", "year": 2020 }, { "abstract": "In this paper, Co3O4 ZnO nanomaterials with Co3O4 doping mass fractions of 0% 2.13% 4.13% and 6.13% were prepared by sol gel method. In order to explain and confirm the influence of the incorporation of Co3O4 on the surface morphology and gas sensitivity of ZnO at a relatively low gas concentration, additional studies such as XRD, XPS, SEM, EDS and UV vis spectroscopy were performed. And its photoelectric response to 100 ppm acetone at near room temperature and visible light irradiation was studied. Due to the formation of P N heterojunctions, the Co3O4 ZnO heterostructural nanoparticles has a highe response to low concentrations of acetone gas than undoped ZnO nanoparticles even at operating temperatures as low as 30oC. The addition of Co3O4 improves the sensitivity and selectivity of ZnO thick films. The sensitivity of the 4.13wt% Co3O4 ZnO sample to 100 ppm acetone at a working temperature of 30oC was 24.36. The light excitation effect was significantly enhanced. Under visible light irradiation, the sensitivity can reach 37.21. In addition, the Co3O4 ZnO P N heterojunction model was combined with visible light excitation theory to further explore the mechanism of gas sensing reaction.", "author_names": [ "Nan Han", "Guofeng Pan", "Jie Zheng", "Ru Wang", "Yudong Wang" ], "corpus_id": 146161839, "doc_id": "146161839", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Co3O4 ZnO P N Heterostructure Nanomaterials Film and its Enhanced Photoelectric Response to Visible Lights at Near Room Temperature", "venue": "", "year": 2019 }, { "abstract": "Developing cheap and stable electrocatalysts is considered the key factor to achieve the large scale application of fuel cells. In this paper, three dimensional (3D) porous Co doped vanadium nitride (VN) nanosheet assembled microflowers are prepared with a facile solvothermal approach followed by nitridation at 500 degC in NH3. It is found that the microflower morphology and the Co doping both significantly enhance the oxygen reduction reaction (ORR) performance of the materials. Because the unique 3D porous structure provides higher specific surface area and more active sites as well as enriching the d electrons of V via doping, Co also improves the intrinsic activity of VN. Our optimal V0.95Co0.05N microflowers achieve a half wave potential for the ORR of up to 0.80 V in 0.1 M KOH solution, which is almost comparable to that of commercial 20% Pt/C. More importantly, the catalysts show superior durability with little current decline (less than 12% during chronoamperometric evaluation for over 25 000 s. These features make the V0.95Co0.05N microflowers attractive for fuel cell applications.", "author_names": [ "Haibo Tang", "Jun-ming Luo", "Xin Long Tian", "Yuanyuan Dong", "Jianhai Li", "Mingrui Liu", "Li-na Liu", "Huiyu Song", "Shijun Liao" ], "corpus_id": 206479275, "doc_id": "206479275", "n_citations": 24, "n_key_citations": 0, "score": 0, "title": "Template Free Preparation of 3D Porous Co Doped VN Nanosheet Assembled Microflowers with Enhanced Oxygen Reduction Activity.", "venue": "ACS applied materials interfaces", "year": 2018 }, { "abstract": "This article is the first demonstration of a molybdenum disulfide (MoS2)/tricobalt tetraoxide (Co3O4) nanocomposite film sensor toward NH3 detection. The MoS2/Co3O4 film sensor was fabricated on a substrate with interdigital electrodes via layer by layer self assembly route. The surface morphology, nanostructure, and elemental composition of the MoS2/Co3O4 samples were examined by scanning electron microscopy, transmission electron microscopy, X ray diffraction, energy dispersive spectrometry, and X ray photoelectron spectroscopy. The characterization results confirmed its successful preparation and rationality. The NH3 sensing properties of the sensor for ultra low concentration detection were investigated at room temperature. The experimental results revealed that high sensitivity, good repeatability, stability, and selectivity and fast response/recovery characteristics were achieved by the sensor toward NH3. Moreover, the MoS2/Co3O4 nanocomposite film sensor exhibited significant enhancement in ammonia sensing properties in comparison with the MoS2 and Co3O4 counterparts. The underlying sensing mechanisms of the MoS2/Co3O4 nanocomposite toward ammonia were ascribed to the layered nanostructure, synergistic effect, and heterojunction created at the interface of n type MoS2 and p type Co3O4. The synthesized MoS2/Co3O4 nanocomposite proved to be an excellent candidate for constructing high performance ammonia sensor for various applications.", "author_names": [ "Dongzhi Zhang", "Chuanxing Jiang", "Peigang Li", "Yan'e Sun" ], "corpus_id": 5141206, "doc_id": "5141206", "n_citations": 159, "n_key_citations": 0, "score": 0, "title": "Layer by Layer Self assembly of Co3O4 Nanorod Decorated MoS2 Nanosheet Based Nanocomposite toward High Performance Ammonia Detection.", "venue": "ACS applied materials interfaces", "year": 2017 }, { "abstract": "Two dimensional materials often show a range of intriguing electronic, catalytic, and optical properties that differ greatly from conventional nanoparticles. Herein, we demonstrate the large scale preparation of sub 3 nm atomic layers Co3O4 nanofilms with a nonsurfactant and substrate free hydrothermal method. This successful preparation of ultrathin nanofilms highlighted the reconstruction of cobalt ammonia complexes and synergistic effect of free ammonia and nitrate on film growth control. Subsequent performance tests uncovered that these sub 3 nm atomic layer Co3O4 nanofilms exhibited an ultrahigh specific capacitance of 1400 F/g in the first galvanostatic charge/discharge test. The specific capacitance of Co3O4 nanofilms only slightly decayed less than 3% after 1500 cycling tests. With some parameter adjustments, similar Co(OH)2 nanofilms with a thickness of 3.70 0.10 nm were also prepared. The Co(OH)2 nanofilms possessed maximum specific capacitance of 1076 F/g and peak performance attenuation of about 2% after a cycle stability test.", "author_names": [ "Chao Feng", "Jinfeng Zhang", "Yu He", "Cheng Zhong", "Wenbin Hu", "Lei Liu", "Yida Deng" ], "corpus_id": 40340509, "doc_id": "40340509", "n_citations": 197, "n_key_citations": 2, "score": 0, "title": "Sub 3 nm Co3O4 nanofilms with enhanced supercapacitor properties.", "venue": "ACS nano", "year": 2015 }, { "abstract": "Efficient bifunctional catalysts for electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are highly desirable due to their wide applications in fuel cells and rechargeable metal air batteries. However, the development of nonprecious metal catalysts with comparable activities to noble metals is still challenging. Here we report a one step wet chemical synthesis of Ni /Mn promoted mesoporous cobalt oxides through an inverse micelle process. Various characterization techniques including powder X ray diffraction (PXRD) N2 sorption, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) confirm the successful incorporation of Ni and Mn leading to the formation of Co Ni(Mn) O solid solutions with retained mesoporosity. Among these catalysts, cobalt oxide with 5% Ni doping demonstrates promising activities for both ORR and OER, with an overpotential of 399 mV for ORR (at 3 mA/cm(2) and 381 mV (at 10 mA/cm(2) for OER. Furthermore, it shows better durability than precious metals featuring little activity decay throughout 24 h continuous operation. Analyses of cyclic voltammetry (CV) X ray photoelectron spectroscopy (XPS) Raman, and O2 temperature programmed desorption (O2 TPD) reveal that redox activity of Co(3+ to Co(4+ is crucial for OER performance, while the population of surface oxygen vacancies and surface area determine ORR activities. The comprehensive investigation of the intrinsic active sites for ORR and OER by correlating different physicochemical properties to the electrochemical activities is believed to provide important insight toward the rational design of high performance electrocatalysts for ORR and OER reactions.", "author_names": [ "Wenqiao Song", "Zheng Ren", "Sheng-Yu Chen", "Yongtao Meng", "Sourav Biswas", "Partha Nandi", "Heather A Elsen", "Pu-Xian Gao", "Steven L Suib" ], "corpus_id": 206427976, "doc_id": "206427976", "n_citations": 123, "n_key_citations": 1, "score": 0, "title": "Ni and Mn Promoted Mesoporous Co3O4: A Stable Bifunctional Catalyst with Surface Structure Dependent Activity for Oxygen Reduction Reaction and Oxygen Evolution Reaction.", "venue": "ACS applied materials interfaces", "year": 2016 }, { "abstract": "The photocatalytic activity of TiO2 nanotubes can be improved through the construction of a Z scheme composite, where photogenerated electrons from TiO2 recombine with the photogenerated holes in a coupled semiconductor. This arrangement allows for improved oxidation due to the residual holes of TiO2 and better chemical reduction due to the greater availability of the photogenerated electrons of the coupled semiconductor. Efficient Z scheme porous g C3N4/TiO2 nanotube (PCN/TNTs) composites were developed here using a solid sublimation and transition approach, with Al O links added by an impregnation method to increase interfacial linkages between the PCN and TNTs. The best results for photocatalytic CO2 conversion were obtained using 0.7PCN/0.4Al/TNTs, as shown by production of 54.9 0.70 mg L 1 h 1 of acetic acid, 42.7 0.54 mg L 1 h 1 of formic acid, and 45.4 0.55 mg L 1 h 1 of methanol, which were about 3.8, 4.3, and 4.2 times that produced with bare TNTs. Photocatalytic 2,4 dichlorophenol decompos.", "author_names": [ "Jing Wu", "Yujie Feng", "Bruce E Logan", "Changchao Dai", "Xiaoyu Han", "Da Li", "Jia Liu" ], "corpus_id": 202075312, "doc_id": "202075312", "n_citations": 24, "n_key_citations": 0, "score": 0, "title": "Preparation of Al O Linked Porous g C3N4/TiO2 Nanotube Z Scheme Composites for Efficient Photocatalytic CO2 Conversion and 2,4 Dichlorophenol Decomposition and Mechanism", "venue": "ACS Sustainable Chemistry Engineering", "year": 2019 }, { "abstract": "The article describes synthesis and sensing properties of SnO2 Co3O4 spheres composed of aggregated nanoparticles. Co3O4 was doped with pristine SnO2, and the resulting nanocomposite spheres were incorporated into a silicon adhesive. This material is shown to enable impedimetric sensing of relative humidity (RH) The impedance of the material decreases by 80% at a 1.0 kHz working frequency and by a factor of 2500 at 100 Hz. Capacitance increases by 70% at 1.0 kHz frequency and by a factor of 1509 at 100 Hz. The sensor works in the 10 90% RH range at temperatures from 10 to 80 degC. SnO2 Co3O4 based humidity sensor exhibited high sensitivity which makes it suitable material for the utilization in humidity meter.", "author_names": [ "Alaud Din", "Khasan S Karimov", "Kalsoom Akhtar", "M Imran Khan", "Muhammad Tariq Saeed Chani", "Murad Ali Khan", "Abdullah M Asiri", "Sher Bahadar Khan" ], "corpus_id": 138030709, "doc_id": "138030709", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Impedimetric humidity sensor based on the use of SnO2 Co3O4 spheres", "venue": "Journal of Materials Science: Materials in Electronics", "year": 2016 }, { "abstract": "The one dimensional (1D) mesoporous and interconnected nanoparticles (NPs) enriched composite Co3O4 CuO nanofibers (NFs) in the ratio Co:Cu 1/4 (Co3O4 CuO NFs) composite have been synthesized by electrospinning and calcination of mixed polymeric template. Not merely the mesoporous composite Co3O4 CuO NFs but also single mesoporous Co3O4 NFs and CuO NFs have been produced for comparison. The choice of mixed polymer templates such as polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) for electrospinning is responsible for the formation of 1D mesoporous NFs. The HR TEM result showed evolution of interconnected nanoparticles (NPs) and creation of mesoporosity in all electrospun NFs. The quantum confinement is due to NPs within NFs and has been proved by the surface enhanced Raman scattering (SERS) study and the UV vis NRI diffuse reflectance spectra (DRS) The high intense photoluminescence (PL) spectra showing blue shift of all NFs also confirmed the quantum confinement phenomena. The lowering of PL spectrum after mixing of CuO in Co3O4 nanofibers framework (Co3O4 CuO NFs) proved CuO as an efficient visible light response low cost cocatalyst/charge separator. The red shifting of the band gap in composite Co3O4 CuO NFs is due to the internal charge transfer between Co2+ to Co3+ and Cu2+ proved by UV vis absorption spectroscopy. Creation of oxygen vacancies by mixing of CuO and Co3O4 also prevents the electron hole recombination and enhances the photocatalytic activity in composite Co3O4 CuO NFs. The photocurrent density, Mott Schottky (MS) and electrochemical impedance spectroscopy (EIS) studies of all NFs favor the high photocatalytic performance. The mesoporous composite Co3O4 CuO NFs exhibits high photocatalytic activity toward phenolic compounds degradation as compared to the other two NFs (Co3O4 NFs and CuO NFs) The kinetic study of phenolic compounds followed first order rate equation. The high photocatalytic activity of composite Co3O4 CuO NFs is attributed to the formation of mesoporosity and interconnected NPs within NFs framework, quantum confinement, extended light absorption property, internal charge transfer, and effective photogenerated charge separations.", "author_names": [ "Tamer Uyar" ], "corpus_id": 206461396, "doc_id": "206461396", "n_citations": 51, "n_key_citations": 0, "score": 0, "title": "Morphological Control of Mesoporosity and Nanoparticles within Co3O4 CuO Electrospun Nanofibers: Quantum Confinement and Visible Light Photocatalysis Performance.", "venue": "ACS applied materials interfaces", "year": 2017 }, { "abstract": "Co(3)O(4) nanoparticles (NPs) with an average diameter of about 20 nm were synthesized by using MOFs as a template. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the as prepared Co(3)O(4) NPs. Fourier transform infrared spectroscopy (FT IR) and X ray diffraction (XRD) were used to confirm the structure of the Co(3)O(4) NPs. Then the Co(3)O(4) NPs were modified on a glassy carbon electrode (GCE) to obtain a non enzymatic glucose and H(2)O(2) sensor. The NPs show electrocatalytic activity toward oxidation of glucose and H(2)O(2) in alkaline medium. For glucose detection, the developed sensor shows a short response time (less than 6 s) a high sensitivity of 520.7 mA mM( 1) cm( 2) a detection limit of 0.13 mM (S/N 3) and good selectivity. The high concentration of NaCl does not poison the electrode. Its application for the detection of glucose in a human blood serum sample shows good agreement with the results obtained from the hospital. Furthermore, the proposed sensor was used for the detection of H(2)O(2) The results indicate that the detection limit and sensitivity for H(2)O(2) are 0.81 mM and 107.4 mA mM( 1) cm( 2) respectively. Determination of H(2)O(2) concentration in a disinfectant sample by the proposed biosensor also showed satisfactory result. The high sensitivity and low detection limit can be attributed to the excellent electrocatalytic performance of the as prepared Co(3)O(4) NPs. These results demonstrate that the as prepared Co(3)O(4) NPs have great potential applications in the development of sensors for enzyme free detection of glucose and H(2)O(2)", "author_names": [ "Chuantao Hou", "Qin Xu", "Lina Yin", "Xiaoya Hu" ], "corpus_id": 24734001, "doc_id": "24734001", "n_citations": 139, "n_key_citations": 4, "score": 0, "title": "Metal organic framework templated synthesis of Co3O4 nanoparticles for direct glucose and H2O2 detection.", "venue": "The Analyst", "year": 2012 } ]

[ { "abstract": "A ferroelectric memory field effect transistor (FET) with a Pt SrBi/sub 2/Ta/sub 2/O/sub 9/ Hf Al O Si gate stack was fabricated and its electrical properties were characterized. The insulating and ferroelectric layers were successively deposited by a laser ablation technique. Excellent data retention characteristics were obtained. The drain currents of on and off states were measured as a function of time, after /spl plusmn/6 V poling voltage applied to the gate electrode. The current ratio of the on and off states was more than 10/sup 6/ even after 12 days. Moreover, after 10/sup 12/ cycles of /spl plusmn/8 V pulses, this ratio was also more than 10/sup 6/", "author_names": [ "Shigeki Sakai", "Rajangam Ilangovan" ], "corpus_id": 8557580, "doc_id": "8557580", "n_citations": 167, "n_key_citations": 6, "score": 1, "title": "Metal ferroelectric insulator semiconductor memory FET with long retention and high endurance", "venue": "IEEE Electron Device Letters", "year": 2004 }, { "abstract": "A metal ferroelectric insulator semiconductor (MFIS) field effect transistor (FET) composed of a Pt/SrBi2Ta2O9(SBT)/Hf Al O/Si stack with a long data retention over 106 s was fabricated. The poling voltages to obtain the long data retention were 6 V. The memory window in the drain current vs gate voltage (Id Vg) curve increased monotonically with increasing gate scan voltage amplitude (Vscan) up to Vscan=6 V. This behavior indicates that the device operation is based on unsaturated ferroelectric polarization switching. A direct cross sectional transmission electron microscopy image of the Pt/SBT/Hf Al O/Si stack and the electrical properties of a Pt/Hf Al O/Si metal insulator semiconductor (MIS) FET used as a reference showed the existence of a 4.4 nm thick interfacial layer between the Hf Al O layer and the Si substrate, which can explain the device operation with the unsaturated ferroelectric polarization. The results thus concluded that saturation of ferroelectric polarization is not essential for obtaining the long data retention.", "author_names": [ "Shigeki Sakai", "Rajangam Ilangovan", "Mitsue Takahashi" ], "corpus_id": 119934372, "doc_id": "119934372", "n_citations": 44, "n_key_citations": 1, "score": 0, "title": "Pt/SrBi2Ta2O9/Hf Al O/Si Field Effect Transistor with Long Retention Using Unsaturated Ferroelectric Polarization Switching", "venue": "", "year": 2004 }, { "abstract": "A ferroelectric gate FET (FeFET) is significant for 1T FeRAM. Among fabricated Pt/SrBi/sub 2/Ta/sub 2/O/sub 9/(HfO/sub 2//sub x/(Al/sub 2/O/sub 3//sub 1 x//Si FeFETs, we find that the optimum buffer layer composition ratio, x, of HfO/sub 2/ and Al/sub 2/O/sub 3/ exists around 0.75. A FeFET of x 0.75 with high k buffer layer and low leakage current shows long data retention.", "author_names": [ "Shigeki Sakai", "M Takahashi", "Rajangam Ilangovan" ], "corpus_id": 1744395, "doc_id": "1744395", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Long retention ferroelectric gate FET with a (HfO/sub 2//sub x/(Al/sub 2/O/sub 3//sub 1 x/ buffer insulating layer for 1T FeRAM", "venue": "IEDM Technical Digest. IEEE International Electron Devices Meeting, 2004.", "year": 2004 }, { "abstract": "Potassium tantalate niobate single crystals have been grown for Nb concentrations 0.7, 0.5 and 0.35. The step cooling technique was adopted to avoid the striations and composition gradient. The composition was analysed using electron probe microanalysis. Dielectric study was carried out for the grown crystals.", "author_names": [ "R Ilangovan", "Ganesan Ravi", "C Subramanian", "P Ramasamy", "Shigeki Sakai" ], "corpus_id": 97285902, "doc_id": "97285902", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Growth and characterization of potassium tantalate niobate single crystals by the step cooling technique", "venue": "", "year": 2002 }, { "abstract": "Ferroelectric materials and their applications have been known and developed sine 1920s and nowadays they are one of the most important materials used in the memory, optical device and sensor device production. Although they are possible to utilize ferroelectric characteristics for a wide variety of applications, but a primary object of recent research activities is directed toward the development of nonvolatile memories. In this study we focused on enhancement of electrical and data retention characteristics of memory devices based on metal ferroelectric insulator semiconductor (MFIS) structure by radical irradiation treatments. Ferroelectric memories has gathered much attention since they show ultimate properties of nonvolatility, low power consumption, and high speed operation [Hai, L. V. etc. (2010) Hai, L. V. etc. (2006 a) Tarui Y, ect. (1997) Scott, J. F. (2000) Sakai, S. Ilangovan, R. (2004) Ishiwara, H. (2001) The well known ferroelectric memory applications of ferroelectric capacitor type random access memories (FeRAM) have been successfully developed and commercially available at present [Sakai, S. etc. (2010) Another type of ferroelectric memory is a ferroelectric field effect transistor (FeFET) in which a ferroelectric layer was inserted between top gate and oxide layer of an FET, as shown in. In recent years, memory cells of the FeFETs were selected as the most suitable candidate to alternate for floating gate (FG) memory cells in the NAND flash memory, due to the fact that FeFET cells exhibited superior characteristics from viewpoints of downscale ability, long endurance characteristics, and low voltage operation, in comparison with the FG cells [Hai, L. V. etc. (2010) The new Fe NAND flash memory based on the FeFETs can open a new generation of the NAND flash memory which meets fully requirements of high speed USB flash drives, MP3 players, flash memory in portable devices and solid state drive (SSD) applications [Hai, L. V. etc. (2010) Although many efforts have been made by many research groups to improve but the FeFET type memories still need more investigations to satisfy for commercial application as some problems were pointed out. It is extremely difficult to fabrication FeFETs with high quality ferroelectric and insulator films therefore they always do not show acceptable retention and electrical properties. We attribute the relatively low", "author_names": [ "Le Van Hai", "Takeshi Kanashima", "Masanori Okuyama" ], "corpus_id": 53454175, "doc_id": "53454175", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Studies on Electrical Properties and Memory Retention Enhancement of Metal Ferroelectric Insulator Semiconductor with Radical Irradiation Treatments", "venue": "", "year": 2018 }, { "abstract": "Verocytotoxigenic Escherichia coli (VTEC) can contaminate crop plants, potentially using them as secondary hosts, which can lead to food borne infection. Currently, little is known about the influence of the specific plant species on the success of bacterial colonization. As such, we compared the ability of the VTEC strain, E. coli O157:H7 'Sakai, to colonize the roots and leaves of four leafy vegetables: spinach (Spinacia oleracea) lettuce (Lactuca sativa) vining green pea (Pisum sativum) and prickly lettuce (Lactuca serriola) a wild relative of domesticated lettuce. Also, to determine the drivers of the initial response on interaction with plant tissue, the whole transcriptome of E. coli O157:H7 Sakai was analyzed following exposure to plant extracts of varying complexity (spinach leaf lysates or root exudates, and leaf cell wall polysaccharides from spinach or lettuce) Plant extracts were used to reduce heterogeneity inherent in plant microbe interactions and remove the effect of plant immunity. This dual approach provided information on the initial adaptive response of E. coli O157:H7 Sakai to the plant environment together with the influence of the living plant during bacterial establishment and colonization. Results showed that both the plant tissue type and the plant species strongly influence the short term (1 h) transcriptional response to extracts as well as longer term (10 days) plant colonization or persistence. We show that propagation temperature (37 vs. 18degC) has a major impact on the expression profile and therefore pre adaptation of bacteria to a plant relevant temperature is necessary to avoid misleading temperature dependent wholescale gene expression changes in response to plant material. For each of the plant extracts tested, the largest group of (annotated) differentially regulated genes were associated with metabolism. However, large scale differences in the metabolic and biosynthetic pathways between treatment types indicate specificity in substrate utilization. Induction of stress response genes reflected the apparent physiological status of the bacterial genes in each extract, as a result of glutamate dependent acid resistance, nutrient stress, or translational stalling. A large proportion of differentially regulated genes are uncharacterized (annotated as hypothetical) which could indicate yet to be described functional roles associated with plant interaction for E. coli O157:H7 Sakai.", "author_names": [ "Louise Crozier", "Peter E Hedley", "Jenny Morris", "Carol Wagstaff", "Simon C Andrews", "Ian K Toth", "Robert W Jackson", "Nicola Jean Holden" ], "corpus_id": 11689652, "doc_id": "11689652", "n_citations": 26, "n_key_citations": 4, "score": 0, "title": "Whole Transcriptome Analysis of Verocytotoxigenic Escherichia coli O157:H7 (Sakai) Suggests Plant Species Specific Metabolic Responses on Exposure to Spinach and Lettuce Extracts", "venue": "Front. Microbiol.", "year": 2016 }, { "abstract": "We revisit and extend previous calculations of glueball decay rates in the Sakai Sugimoto model, a holographic top down approach for QCD with chiral quarks based on D8 probe branes in Witten's holographic model of nonsupersymmetric Yang Mills theory. The rates for decays into two pions, two vector mesons, four pions, and the strongly suppressed decay into four pi0 are worked out quantitatively, using a range of the 't Hooft coupling which closely reproduces the decay rate of rho and omega mesons and also leads to a gluon condensate consistent with QCD sum rule calculations. The lowest holographic glueball, which arises from a rather exotic polarization of gravitons in the supergravity background, turns out to have a significantly lower mass and larger width than the two widely discussed glueball candidates f0(1500) and f0(1710) The lowest nonexotic and predominantly dilatonic scalar mode, which has a mass of 1487 MeV in the Witten Sakai Sugimoto model, instead provides a narrow glueball state, and we conjecture that only this nonexotic mode should be identified with a scalar glueball component of f0(1500) or f0(1710) Moreover the decay pattern of the tensor glueball is determined, which is found to have a comparatively broad total width when its mass is adjusted to around or above 2 GeV.", "author_names": [ "Frederic Brunner", "Denis Parganlija", "Anton K Rebhan" ], "corpus_id": 118552918, "doc_id": "118552918", "n_citations": 61, "n_key_citations": 10, "score": 0, "title": "Glueball Decay Rates in the Witten Sakai Sugimoto Model", "venue": "", "year": 2015 }, { "abstract": "We estimate the consequences of finite masses of pseudoscalar mesons on the decay rates of scalar glueballs in the Witten Sakai Sugimoto model, a top down holographic model of low energy QCD, by extrapolating from the calculable vertex of glueball fields and the e^ meson that follows from the Witten Veneziano mechanism for giving mass to the latter. Evaluating the effect on the recently calculated decay rates of glueballs in the Witten Sakai Sugimoto model, we find a strong enhancement of the decay of scalar glueballs into kaons and e mesons, in fairly close agreement with experimental data on the glueball candidate f_{0}(1710)", "author_names": [ "Frederic Brunner", "Anton K Rebhan" ], "corpus_id": 14043746, "doc_id": "14043746", "n_citations": 42, "n_key_citations": 2, "score": 0, "title": "Nonchiral Enhancement of Scalar Glueball Decay in the Witten Sakai Sugimoto Model.", "venue": "Physical review letters", "year": 2015 }, { "abstract": "A brief review of the Witten Sakai Sugimoto model is given, which is a top down holographic model of low energy QCD with chiral quarks derived from type IIA superstring theory. The main predictions of the model, in particular concerning meson spectra, the gluon condensate, the QCD string tension, the mass of the \\eta' and of baryons are discussed and compared quantitatively with available experimental and/or lattice results. Then some recent results of potential interest to the physics program at the future FAIR facility are presented: The spectrum of glueballs and their decay rates into pions, and the phase diagram of QCD at finite temperature, density, and magnetic field strength.", "author_names": [ "Anton K Rebhan" ], "corpus_id": 3660262, "doc_id": "3660262", "n_citations": 39, "n_key_citations": 1, "score": 0, "title": "The Witten Sakai Sugimoto model: A brief review and some recent results", "venue": "", "year": 2014 }, { "abstract": "A bstractThe Sakai Sugimoto model is the preeminent example of a string theory description of holographic QCD, in which baryons correspond to topological solitons in the bulk. Here we investigate the validity of various approximations of the Sakai Sugimoto soliton that are used widely to study the properties of holographic baryons. These approximations include the flat space self dual instanton, a linear expansion in terms of eigenfunctions in the holographic direction and an asymptotic power series at large radius. These different approaches have produced contradictory results in the literature regarding properties of the baryon, such as relations for the electromagnetic form factors. Here we determine the regions of validity of these various approximations and show how to relate different approximations in contiguous regions of applicability. This analysis clarifies the source of the contradictory results in the literature and resolves some outstanding issues, including the use of the flat space self dual instanton, the detailed properties of the asymptotic soliton tail, and the role of the UV cutoff introduced in previous investigations. A consequence of our analysis is the discovery of a new large scale, that grows logarithmically with the 't Hooft coupling, at which the soliton fields enter a nonlinear regime. Finally, we provide the first numerical computation of the Sakai Sugimoto soliton and demonstrate that the numerical results support our analysis.", "author_names": [ "Stefano Bolognesi", "Paul Sutcliffe" ], "corpus_id": 118431219, "doc_id": "118431219", "n_citations": 37, "n_key_citations": 2, "score": 0, "title": "The Sakai Sugimoto soliton", "venue": "", "year": 2014 } ]

[ { "abstract": "Abstract Metal organic framework (MOF) is one of the most promising precursors for the fabrication of advanced photo semiconductors or cocatalysts due to its diverse structures and unique properties. However, the primitive MOF can not show greater potential and application value. Here Co ZIF 67 dodecahedron was controllably carved via the different ways for efficiently boosting the photo catalytic property of hydrogen evolution. This reasonable design can not only preserve polyhedron characteristics with the large specific surface area of ZIF 67, but also improve H2 evolution performance in Eosin Y sensitization system, which depends on the enhanced electronegativity of the surface of ZIF 6 derived polyhedrons and the quite strong adsorption of H and H2O by Co site. Meanwhile, ligand group or hetero atom adjacent to metal Co atom owing to the introduction of electronegative heteroatoms overturns the inherent structure and properties of ZIF 67 to a certain extent thereby rearranging the electron distribution and improving transfer efficiency of charge carriers. Additionally, the structural evolution of ZIF 67 constructs an efficient transport channels for migration of electron, which eliminates the resistance to be overcome when electrons migrate from the inside of a semiconductor to the surface. And the increase of optical absorption density caused by hyperchromicity effect is also a factor that can not be ignored for evolving the co catalytic performance of ZIF 67.", "author_names": [ "Yanbing Li", "Zhiliang Jin", "Tiansheng Zhao" ], "corpus_id": 208736367, "doc_id": "208736367", "n_citations": 47, "n_key_citations": 0, "score": 1, "title": "Performance of ZIF 67 Derived fold polyhedrons for enhanced photocatalytic hydrogen evolution", "venue": "", "year": 2020 }, { "abstract": "Abstract Engineering non precious metal electrocatalysts that accompanied with excellent performance toward oxygen evolution reaction (OER) remains a great challenge. Herein, a class of CoSe2 nano vesicle that derived from ZIF 67 nanocubes is fabricated by a facile one pot hydrothermal method. Benefitting from the hollow structure, abundant oxygen vacancies, strong synergistic effect between Co and Se, and facilitated electron transfer rate, the optimized CoSe2 30 exhibits excellent OER performance with a low overpotential of 287 mV at the current density of 10 mA cm 2, and small Tafel slope of 54.3 mV dec 1, which is much superior to the reported OER electrocatalyst derived from ZIF 67 via complicated prepared method. In addition, these electrocatalysts can also maintain original current density and voltage after long term chronoamperometry and chronopotentiometry tests, respectively. This work demonstrates a favorable hydrothermal method for transforming cubic ZIF 67 nanocrystal structure into hollow CoSe2 nano vesicle with excellent electrocatalytic performance for OER and thus opens up a sunshine road for the practical applications of water electrolysis.", "author_names": [ "Zhao Li", "Zizhan Jiang", "Wenyou Zhu", "Changchun He", "Pingshan Wang", "Xiang Wang", "Tongxiang Li", "Lin Tian" ], "corpus_id": 208759008, "doc_id": "208759008", "n_citations": 33, "n_key_citations": 0, "score": 0, "title": "Facile preparation of CoSe2 nano vesicle derived from ZIF 67 and their application for efficient water oxidation", "venue": "", "year": 2020 }, { "abstract": "Potassium ion batteries (KIB) have become a compelling energy storage system owing to their cost effectiveness and the high abundance of potassium in comparison with lithium. However, its practical applications have been thwarted by a series of challenges, including marked volume expansion and sluggish reaction kinetics caused by the large radius of potassium ions. In line with this, the exploration of reliable anode materials affording high electrical conductivity, sufficient active sites, and structural robustness is the key. The synthesis of ZIF 8@ZIF 67 derived nitrogen doped porous carbon confined CoP polyhedron architectures (NC@CoP/NC) to function as innovative KIB anode materials is reported. Such composites enable an outstanding rate performance to harvest a capacity of 200 mAh g 1 at 2000 mA g 1 Additionally, a high cycling stability can be gained by maintaining a high capacity retention of 93% after 100 cycles at 100 mA g 1 Furthermore, the potassium ion storage mechanism of the NC@CoP/NC anode is systematically probed through theoretical simulations and experimental characterization. This contribution may offer an innovative and feasible route of emerging anode design toward high performance KIBs.", "author_names": [ "Yuyang Yi", "Wen Zhao", "Zhihan Zeng", "Chaohui Wei", "Chen Lu", "Yuanlong Shao", "Wenyue Guo", "Shi Xue Dou", "Jingyu Sun" ], "corpus_id": 210866253, "doc_id": "210866253", "n_citations": 46, "n_key_citations": 0, "score": 0, "title": "ZIF 8@ZIF 67 Derived Nitrogen Doped Porous Carbon Confined CoP Polyhedron Targeting Superior Potassium Ion Storage.", "venue": "Small", "year": 2020 }, { "abstract": "Heterogeneous catalysts with precise surface and interface structures are of great interest to decipher the structure property relationships and maintain remarkable stability while achieving high activity. Here, we report the design and fabrication of the new sandwich composites ZIF 8@Au25@ZIF 67[tkn] and ZIF 8@Au25@ZIF 8[tkn] [tkn thickness of shell] by coordination assisted self assembly with well defined structures and interfaces. The composites ZIF 8@Au25@ZIF 67 efficiently catalyzed both 4 nitrophenol reduction and of terminal alkyne carboxylation with CO2 un der ambient conditions with remarkably improved activity and stability, compared to the simple components Au25/ZIF 8 and Au25@ZIF 8, highlighting the highly useful function of the ultrathin shell. In addition, the performances of these compo site sandwich catalysts are conveniently regulated by the shell thickness. This concept and achievements should open a new avenue to the targeted design of well defined nanocatalysts with enhanced activities and stabilities for challenging reac tions.", "author_names": [ "Yapei Yun", "Hongting Sheng", "Kang Bao", "Li Xu", "Yuanyuan Zhang", "Didier Astruc", "Manzhou Zhu" ], "corpus_id": 211099796, "doc_id": "211099796", "n_citations": 31, "n_key_citations": 0, "score": 0, "title": "Design and Remarkable Efficiency of the Robust Sandwich Cluster Composite Nanocatalysts ZIF 8@Au25@ZIF 67.", "venue": "Journal of the American Chemical Society", "year": 2020 }, { "abstract": "Abstract For supercapacitors, development of electrode materials with superior electrochemical performance is urgently needed. Herein, we synthesized novel nickel cobalt sulfide (NiCo2S4) hollow cages as electrode materials for supercapacitors. The NiCo2S4 hollow cages possess a hollow interior and mesoporous structure, which could shorten ion diffusion distance and provide plentiful electroactive sites. Thanks to the appealing structures, the NiCo2S4 hollow cages exhibit an appealing capacitance of 1382 F g 1 at 1 A g 1. Furthermore, asymmetric supercapacitors (ASCs) are fabricated with the synthesized NiCo2S4 and active carbon (AC) as electrodes. The ASC shows an energy density of 35.3 Wh kg 1 at a power density of 750 W kg 1 and an outstanding cycling stability of 79% retention after 10,000 cycles. The excellent performance of NiCo2S4 hollow cages makes them promising candidates in supercapacitors.", "author_names": [ "Pengfei Cai", "Tao Liu", "Liu Yang Zhang", "Bei Cheng", "Jiaguo Yu" ], "corpus_id": 209713311, "doc_id": "209713311", "n_citations": 34, "n_key_citations": 0, "score": 0, "title": "ZIF 67 derived nickel cobalt sulfide hollow cages for high performance supercapacitors", "venue": "", "year": 2020 }, { "abstract": "Abstract Utilized Zn/Co based metal organic framework, we successfully fabricate 1D N doped porous carbon nanofibers anchoring amorphous and graphite carbon encapsulated CoS2 nanoparticles, using a facile electrospinning strategy combined with annealing treatment. Remarkably, the composite as superior anode for sodium ion battery is rationally designed, and also exhibit enhanced Na storage performance. The composite shows a large specific capacity of 876 mAh g 1 at 100 mA g 1 in the initial cycles and an outstanding long term performance (148 mAh g 1 at a current density of 3.2 A g 1 over 1000 cycles) The improved electrochemical performance is ascribed to the 1D porous carbon nanofibers structure and the amorphous and graphite carbon coating, which can relatively inhibit agglomeration of CoS2 nanoparticles, mitigate the volume of the material changes in the process of circulation and provide stabilized electrical conductivity. This research paves the way for extending the 1D metal sulfides and metal organic framework composites toward potential applications.", "author_names": [ "Wenming Zhang", "Ziwei Yue", "Qiming Wang", "Xiaoxi Zeng", "Chaochao Fu", "Qing Li", "Xiaoting Li", "Lide Fang", "Liang Li" ], "corpus_id": 202078930, "doc_id": "202078930", "n_citations": 31, "n_key_citations": 0, "score": 0, "title": "Carbon encapsulated CoS2 nanoparticles anchored on N doped carbon nanofibers derived from ZIF 8/ZIF 67 as anode for sodium ion batteries", "venue": "", "year": 2020 }, { "abstract": "Abstract This study applies two isostructural zeolitic imidazolate frameworks (ZIF 8 and ZIF 67) to rapidly adsorb and remove sulfur mustard (HD) a chemical warfare agent. Because HD is extremely toxic, some of the studies were conducted using an HD simulant, 2 chloroethyl ethyl sulfide (CEES) to understand the effect of solvent polarity on adsorption. Further, CEES and real HD were subsequently adsorbed and removed from aqueous solutions using ZIF 8 or ZIF 67. The adsorption abilities of ZIF 8 and ZIF 67 positively correlated with the polarity of the solvent. In addition, 97% of CEES (2.5 mg in 1 mL) was rapidly adsorbed by ZIF 8 and ZIF 67 within 1 min at 25 degC in a 9:1 (v/v) water/ethanol solution. ZIF 8 and ZIF 67 were also successfully fabricated on cotton, which was removed more than 95% of contaminants from substrates contaminated with the HD simulant. We believe that this work will encourage the development of ZIFs for chemical warfare defense.", "author_names": [ "Ye Rim Son", "Sam Gon Ryu", "Hyun Sung Kim" ], "corpus_id": 208751226, "doc_id": "208751226", "n_citations": 20, "n_key_citations": 0, "score": 0, "title": "Rapid adsorption and removal of sulfur mustard with zeolitic imidazolate frameworks ZIF 8 and ZIF 67", "venue": "Microporous and Mesoporous Materials", "year": 2020 }, { "abstract": "Abstract Given the remarkable performances of metal frame works (MOFs) and ferrocene containing polymers (FCPs) in electronic devices, the research on integration of structure and function for collaborative optimization of electromagnetic wave (EMW) absorption are still missing. Herein, surface grafting and main chain polymerization methods have been employed on the FCPs modifying zeolitic imidazolate framework 67 (ZIF 67) respectively. Polydopamine coated ZIF 67 was precursor for grafting type products (ZIF 67@PDA Fc) while poly (vinyl ferrocene) was for main chain type products (ZIF 67@PVF) Furthermore, the calcined products, polyhedron capsules structured Co3O4@C@a Fe2O3 and Co3O4/a Fe2O3@C microwave absorbers were obtained from ZIF 67@PDA Fc and ZIF 67@PVF for higher performance EMW absorption. The crystal, morphological and chemical structure was detected via XRD, SEM, TEM, FTIR, Raman, XPS techniques. The EMW absorbability was calculated according to transmission line theory. In particular, the minimum reflection loss (RLmin) of Co3O4@C@a Fe2O3 reached 52.2 dB at the thickness of 3.7 mm with effective absorption band (fE) 4.4 GHz. It is worth emphasized that the broadest fE was 6.6 GHz obtained at 2.5 mm with RLmin reaching 38.4 dB. Additionally, the EMW absorption mechanism was also studied based on the dielectric and magnetic properties. This investigation will push forward further research and practical application of metal organic compounds based composites.", "author_names": [ "Zhenguo Gao", "Jiaoqiang Zhang", "Shijie Zhang", "Di Lan", "Zehao Zhao", "Kaichang Kou" ], "corpus_id": 225489216, "doc_id": "225489216", "n_citations": 19, "n_key_citations": 0, "score": 0, "title": "Strategies for electromagnetic wave absorbers derived from zeolite imidazole framework (ZIF 67) with ferrocene containing polymers", "venue": "", "year": 2020 }, { "abstract": "Abstract The fabricated intercalated structure composed of a Co based zeolitic imidazolate framework (ZIF 67) and expanded graphite (EG) has been prepared using a facile and simple one pot hydrothermal reaction. This framework was used to detect heavy metal ions (HMIs) via a square wave anodic stripping voltammetry (SWASV) method for the first time. Here, the composite material is useful for the selective electrochemical detection of nanomolar Cd2+ Pb2+ Cu2+ and Hg2+ in aqueous solutions simultaneously or individually. The operational parameters such as pH, electrolyte, deposition potential, and deposition time were optimized to detect various HMIs. The electrochemical properties and applications of the modified electrode were also studied. The constructed electrochemical sensor displays good performance with a large electrochemically active surface areas, high sensitivity and low limit of detection (LOD) These impressive features originate from the synergistic effects of ZIF 67 and EG. This study proposes a new strategy for heavy metal ion detection using a novel morphology of a metal organic framework (MOF) composite.", "author_names": [ "Laifeng Ma", "Xueyi Zhang", "Muhammad Ikram", "Mohib Ullah", "Hongyuan Wu", "Keying Shi" ], "corpus_id": 219028387, "doc_id": "219028387", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "Controllable synthesis of an intercalated ZIF 67/EG structure for the detection of ultratrace Cd2+ Cu2+ Hg2+ and Pb2+ ions", "venue": "", "year": 2020 }, { "abstract": "Abstract Mixed matrix membranes (MMMs) based on metal organic frameworks (MOFs) have proven to have high separation performance, which has great potential in separation applications. However, unsatisfactory hydrothermal stability is the Achilles' heel of MOFs in practical applications, which seriously hinders the development of MOF based MMMs. Under the advantage of crystal anisotropy, a morphology regulation strategy without post treatment is presented for the first time to efficiently improve the stability of MOF fillers in aqueous solution. Contrary to the regular dodecahedron ZIF 67 crystals, the [211] oriented ZIF 67 nanosheets (NS) can maintain an ordered microporous framework integrally in the aqueous solution of membrane preparation. The exposed [211] crystal face exhibits enhanced stability due to a lower proportion of Co N bond and higher surface atomic density. The flake morphology of ZIF 67 with economic incorporation (5.0 wt offers the MMMs significantly enhanced CO2 permeability of 139.4 barrer and CO2/N2 ideal selectivity of 73.2, improved by 50.7% and 76.0% compared with the pristine polymer membrane. This strategy provides a new idea for improving the hydrothermal stability of MOF materials and extends their separation applications under aqueous conditions.", "author_names": [ "Shou Feng", "Mengqi Bu", "Jiangtao Pang", "Weidong Fan", "Lili Fan", "Haoru Zhao", "Gene Jaehyoung Yang", "Hailing Guo", "Guodong Kong", "Haixiang Sun", "Zixi Kang", "Daofeng Sun" ], "corpus_id": 202080954, "doc_id": "202080954", "n_citations": 23, "n_key_citations": 0, "score": 0, "title": "Hydrothermal stable ZIF 67 nanosheets via morphology regulation strategy to construct mixed matrix membrane for gas separation", "venue": "", "year": 2020 } ]

[ { "abstract": "We report a proof of principle demonstration of Shor's algorithm with photons generated by an on demand semiconductor quantum dot single photon source for the first time. A fully compiled version of Shor's algorithm for factoring 15 has been accomplished with a significantly reduced resource requirement that employs the four photon cluster state. Genuine multiparticle entanglement properties are confirmed to reveal the quantum character of the algorithm and circuit. The implementation realizes the Shor's algorithm with deterministic photonic qubits, which opens new applications for cluster state beyond one way quantum computing.", "author_names": [ "Zhao-Chen Duan", "Jin-Peng Li", "Jian Qin", "Ying Yu", "Yongheng Huo", "Sven Hofling", "Chao-Yang Lu", "Nai-Le Liu", "Kai Chen", "Jian-Wei Pan" ], "corpus_id": 220586577, "doc_id": "220586577", "n_citations": 2, "n_key_citations": 0, "score": 1, "title": "Proof of principle demonstration of compiled Shor's algorithm using a quantum dot single photon source.", "venue": "Optics express", "year": 2020 }, { "abstract": "This paper discusses and demonstrates the construction of a quantum modular exponentiation circuit in the Qiskit simulator for use in Shor's Algorithm for integer factorization problem (IFP) which is deemed to be able to crack RSA cryptosystems when a large qubit quantum computer exists. We base our implementation on Vedral, Barenco, and Ekert (VBE) proposal of quantum modular exponentiation, one of the firsts to explicitly provide the aforementioned circuit. Furthermore, we present an example simulation of how to construct a 7xmod 15 circuit in a step by step manner, giving clear and detailed information and consideration that currently not provided in the existing literature, and present the whole circuit for use in Shor's Algorithm. Our present simulation shows that the 4 bit VBE quantum modular exponentiation circuit can be constructed, simulated, and measured in Qiskit, while the Shor's Algorithm incorporating this VBE approach itself can be constructed but not yet simulated due to an overly large number of QASM instructions.", "author_names": [ "Harashta Tatimma Larasati", "Howon Kim" ], "corpus_id": 231601026, "doc_id": "231601026", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Simulation of Modular Exponentiation Circuit for Shor's Algorithm in Qiskit", "venue": "2020 14th International Conference on Telecommunication Systems, Services, and Applications (TSSA", "year": 2020 }, { "abstract": "Abstract The presented work provides a new prospective of quantum computer hardware development through ballistic nanowires with Rashba effect. We address Rashba effect as a possible mechanism to realize novel qubit gates in nanowires. We apply our results to the design of a new quantum circuit for Fourier algorithm, which shows an improved quantum cost in terms of the number of gates. The current system can be successfully implemented to increase the production of quantum computer experimentally thanks to the absence of impurities. The introduced circuit will enhance the scope of experimental and theoretical research for the realization of other quantum algorithms, such as phase estimation and Shor's algorithms.", "author_names": [ "Ali H Homid", "Mohammed R Sakr", "Abdel-Baset A Mohamed", "Mahmoud Abdel-Aty", "A -S F Obada" ], "corpus_id": 126866965, "doc_id": "126866965", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Rashba control to minimize circuit cost of quantum Fourier algorithm in ballistic nanowires", "venue": "Physics Letters A", "year": 2019 }, { "abstract": "Quantum Kit is a graphical desktop application for quantum circuit simulations. Its powerful, memory efficient computational engine enables large scale simulations on a desktop. The ability to design hybrid circuits, with both quantum and classical bits and controls, is employed to demonstrate Kitaev's approach to Shor's factorization algorithm. For the first time, Shor's factorization of a 24 bit integer is simulated with Quantum Kit in a mere 26 minutes on a modest desktop with Intel Core i5 7400T, 2.4GHz and 12GB RAM, while the largest number factorized so far has been a 20 bit integer run on a supercomputer. For the conventional Shor's algorithm, Quantum Kit is about 35 times faster than previously reported simulation times, whereas, with Kitaev's approach, Quantum Kit is 6 orders of magnitude faster in Shor's factorization of exactly the same number.", "author_names": [ "Archana Tankasala", "Hesameddin Ilatikhameneh" ], "corpus_id": 201107039, "doc_id": "201107039", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Quantum Kit: Simulating Shor's Factorization of 24 Bit Number on Desktop", "venue": "", "year": 2019 }, { "abstract": "Very recently, Monz, et al. [arXiv:1507.08852] have reported the demonstration of factoring 15 using a scalable Shor algorithm with an ion trap quantum computer. In this note, we remark that the report is somewhat misleading because there are three flaws in the proposed circuit diagram of Shor algorithm. We also remark that the principles behind the demonstration have not been explained properly, including its correctness and complexity.", "author_names": [ "Zhengjun Cao", "Lihua Liu" ], "corpus_id": 12110273, "doc_id": "12110273", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "A Note On One Realization of a Scalable Shor Algorithm", "venue": "ArXiv", "year": 2016 }, { "abstract": "Our implementation of the quantum circuit in Shor's algorithm directly follows the circuit described in [1] The circuit is composed of the following modules: Quantum Fourier Transform (QFT) QFT addition, modular QFT addition, modular multiplication, and the controlledUa gate. For each of these modules, our implementation has functions which construct the corresponding circuits, given the input qubits as parameters. Upon completion of the circuit, we follow the process given by [2] to get the period r of y mod N from the output c. From this period, we can find a solution to x 1 mod N Finally, we compute GCD(x 1, N) and GCD(x 1, N) if x is nontrivial, then one of these values will be a factor of X.", "author_names": [ "Alec Brickner-abrickne" ], "corpus_id": 199456504, "doc_id": "199456504", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Shor s Algorithm in Pyquil", "venue": "", "year": 2019 }, { "abstract": "We present a novel and efficient, in terms of circuit depth, design for Shor's quantum factorization algorithm. The circuit effectively utilizes a diverse set of adders based on the Quantum Fourier transform (QFT) Draper's adders to build more complex arithmetic blocks: quantum multiplier/accumulators by constants and quantum dividers by constants. These arithmetic blocks are effectively architected into a quantum modular multiplier which is the fundamental block for the modular exponentiation circuit, the most computational intensive part of Shor's algorithm. The proposed modular exponentiation circuit has a depth of about 2000n2 and requires 9n 2 qubits, where n is the number of bits of the classic number to be factored. The total quantum cost of the proposed design is 1600n3. The circuit depth can be further decreased by more than three times if the approximate QFT implementation of each adder unit is exploited.", "author_names": [ "Archimedes Pavlidis", "Dimitris Gizopoulos" ], "corpus_id": 33128433, "doc_id": "33128433", "n_citations": 29, "n_key_citations": 4, "score": 0, "title": "Fast quantum modular exponentiation architecture for Shor's factoring algorithm", "venue": "Quantum Inf. Comput.", "year": 2014 }, { "abstract": "Recently, Monz, et al. [arXiv:1507.08852] have reported the demonstration of factoring 15 using a scalable Shor algorithm with an ion trap quantum computer. We remark that the report is flawed because there are three flaws in the proposed circuit diagram of Shor algorithm. We also remark that the principles behind the demonstration have not been explained properly, including its correctness and complexity.", "author_names": [ "Zhengjun Cao", "Lihua Liu" ], "corpus_id": 16610274, "doc_id": "16610274", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Comment on \"Realization of a scalable Shor algorithm\"", "venue": "IACR Cryptol. ePrint Arch.", "year": 2015 }, { "abstract": "We present a novel and efficient, in terms of circuit depth, design for Shor's quantum factorization algorithm. The circuit effectively utilizes a diverse set of adders based on the Quantum Fourier.", "author_names": [ "" ], "corpus_id": 222494694, "doc_id": "222494694", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Fast quantum modular exponentiation architecture for Shor's factoring algorithm", "venue": "", "year": 2014 }, { "abstract": "We construct a quantum circuit for Shor's factoring algorithm that uses 2n 2 qubits,where n is the length of the number to be factored. The depth and size of the circuitare O(n3) and O(n3 log n) respectivel) The number of qubits used in the circuit is lessthan that in any other quantum circuit ever constructed for Shor's factoring algorithm.Moreover, the size of the circuit is about half the size of Beauregard's quantum circuitfor Shor's factoring algorithm, which uses 2n 3 qubits.", "author_names": [ "Yasuhiro Takahashi", "Noboru Kunihiro" ], "corpus_id": 36836701, "doc_id": "36836701", "n_citations": 33, "n_key_citations": 2, "score": 0, "title": "A quantum circuit for shor's factoring algorithm using 2n 2 qubits", "venue": "Quantum Inf. Comput.", "year": 2006 } ]

[ { "abstract": "Introduction. The Advent of Ultrathin, Well Contained Semiconductor Heterostructures. A Prerequisite. The Mastering of Semiconductor Purity and Interfaces. The Electronic Properties of Thin Semiconductor Heterostructures. Quantum Well Energy Levels. Triangular Quantum Well Energy Levels. Two Dimensional Density of States. Excitons and Shallow Impurities in Quantum Wells. Tunneling Structures, Coupled Quantum Wells, and Superlattices. Modulation Doping of Heterostructures. n i p i Structures. Optical Properties of Thin Heterostructures. Optical Matrix Element. Selection Rules. Energy Levels, Band Discontinuities, and Layer Fluctuations. Low Temperature Luminescence. Carrier and Exciton Dynamics. Inelastic Light Scattering. Non Linear and Electro Optic Effects. Electrical Properties of Thin Heterostructures. Mobility in Parallel Transport. Hot Electron Effects in Parallel Transport. Perpendicular Transport. Quantum Transport. Applications of Quantized Semiconductor Heterostructures. Electronic Devices Based on Parallel Transport. Electronic Devices Based on Perpendicular Transport. Quantum Well Lasers. Towards 1D and 0D Physics and Devices. One and Zero Dimensional Systems. 1D and 0D Semiconductor Fabrication Techniques. Electrical Applications of 1D and 0D Structures. 1D and 0D Optical Devices. Selected Bibliography. References. Index.", "author_names": [ "Claude Weisbuch", "B Vinter" ], "corpus_id": 137105543, "doc_id": "137105543", "n_citations": 432, "n_key_citations": 15, "score": 1, "title": "Quantum Semiconductor Structures: Fundamentals and Applications", "venue": "", "year": 1991 }, { "abstract": "", "author_names": [ "H von Kanel" ], "corpus_id": 137251772, "doc_id": "137251772", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Quantum semiconductor structures: Fundamentals and applications, by. C. Weisbuch, B. Vinter, Academic Press, London 1991, xii, 252 pp. paperback, $34.96, ISBN 0 12 742680 9 [198]", "venue": "", "year": 1992 }, { "abstract": "", "author_names": [ "Claude Weisbuch", "B Vinter", "C Gignoux" ], "corpus_id": 99506197, "doc_id": "99506197", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Quantum Semiconductor Structures: Fundamentals And Applications By Claude Weisbuch;Borge Vinter", "venue": "", "year": 1991 }, { "abstract": "1. Epitaxial growth of semiconductors D. Vvedensky 2. Electrons in quantum semiconductor structures: an introduction E. Johnson 3. Electrons in quantum semiconductor structures: more advanced systems and methods E. Johnson 4. Phonons in low dimensional semiconductor structures M. Blencowe 5. Localization and transport A. MacKinnon 6. Electronic states and optical properties of quantum wells J. Nelson 7. Nonlinear optics in low dimensional semiconductors C. Phillips 8. Semiconductor lasers A. Khan, P. Stavridou, and G. Parry 9. Mesoscopic devices T. Thornton 10. High speed heterostructure devices J. Harris.", "author_names": [ "K W J Barnham", "Dimitri D Vvedensky" ], "corpus_id": 93146031, "doc_id": "93146031", "n_citations": 48, "n_key_citations": 1, "score": 0, "title": "Low Dimensional Semiconductor Structures: Fundamentals and Device Applications", "venue": "", "year": 2008 }, { "abstract": "Abstract Molecular beam epitaxy of IV VI semiconductor multilayers, quantum dots (QD) and device applications are described. The properties of the IV VI compounds differ in several respects from zinc blende III V or II VI semiconductors. This has significant consequences on the growth processes of molecular beam epitaxy as well as for the electronic properties of quantum wells and superlattices. QDs can be obtained by the Stranski Krastanov growth mode as well as by epitaxial phase separation and nanoprecipitation. In the first case, excellent three dimensional ordering and stacking of QDs in superlattices can be achieved due to the high elastic anisotropy, leading to the formation of three dimensional QD crystals. In the second case, strong mid infrared emission of QDs at room temperature has been obtained that is tunable over a wide spectral region. The main application of IV VI or lead salt compounds is in mid infrared optoelectronic devices, and examples for diode lasers, vertical cavity surface emitting laser, and microdisc lasers are described.", "author_names": [ "Gunther Springholz" ], "corpus_id": 139484594, "doc_id": "139484594", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Molecular Beam Epitaxy of IV VI Semiconductors: Fundamentals, Low dimensional Structures, and Device Applications", "venue": "", "year": 2018 }, { "abstract": "Richard Feynman famously said 'there's plenty of room at the bottom' and surely one of the most fashionable and scientifically interesting subfields of modern nanotechnology is plasmonics. Indeed, clever manipulation of the collective excitation of conduction electrons in certain materials is predicted to lead to some very exotic devices, such as invisibility cloaks and perfect lenses. Here, Alexey Toropov and Tatiana Shubina, from the world renowned Ioffe Institute in St. Petersburg, take us on a journey with a semiconductor physicist's eyed view of how plasmonic effects can lead to some weird and wonderful phenomena in nanostructures. As science becomes increasingly interdisciplinary, books such as these, which encompass topics from the quantum theory of semiconductors to the electrodynamics of conducting structures to materials science, all in a brisk but didactic way, are tremendously worthwhile. The book is organised into three parts. Firstly, we are met with a helpful warm up and refresher of the fundamentals underpinning the rest of the book this includes electronic bandstructure theory, surface plasmons and optics in semiconductors. The middle part focuses on a wealth of intriguing materials, including an up to date account of the graphene as a plasmonic material, as well as the more traditional quantum wells, quantum dots and III V and II V semiconductors. The final part deals with light matter in metal semiconductor structures, before concluding with a fascinating account of the very frontiers of plasmonic applications truly rich with big ideas. Can plasmonic antennas efficiently concentrate light fields in a sub wavelength volume? Will plasmonic solar cells aid the renewable energy revolution? Can plasmonic waveguides and quantum cascade lasers finally fill the underutilised terahertz region of the electromagnetic spectrum? Black and white figures are liberally scattered throughout the book, displaying sketches, cartoons and experimental and theoretical curves which will undoubtedly aid the readers understanding of the fascinating concepts being discussed. Importantly, the authors are also not afraid to produce the underlying equations in their full glory too. After all, whilst a picture is worth a thousand words, an equation is worth a thousand pictures. A pleasant stylistic touch is the use of snappy 'concluding remarks' which digest the preceding chapter into a mere handful of sentences. Furthermore, the book is supremely well referenced and is the perfect starting point to delve further into the intricacies of the subjects at hand. Significantly, references to journal papers include the title of the paper, which greatly assists the modern practice of finding papers by internet searches and is most welcome (titles are somewhat inexplicably missing from other recent physics books) In summary, the authors have delivered an essential book for both postgraduates working in the area of plasmonics in nanostructures, as well as more experienced researchers requiring a handy reference book on this zeitgeisty topic.", "author_names": [ "Nikolaos E Myridis" ], "corpus_id": 124366308, "doc_id": "124366308", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Laser measurement technology: fundamentals and applications, by Axel Donges and Reinhard Noll", "venue": "", "year": 2016 }, { "abstract": "Confinement of light into small volumes has become an essential requirement for photonic devices; examples of this trend are provided by optical fibers, integrated optical circuits, semiconductor lasers, and photonic crystals. Optical dielectric resonators supporting Whispering Gallery Modes (WGMs) represent another class of cavity devices with exceptional properties, like extremely small mode volume, very high power density, and very narrow spectral linewidth. WGMs are now known since more than 100 years, after the papers published by John William Strutt (Lord Rayleigh) but their importance as unique tools to study nonlinear optical phenomena or quantum electrodynamics, and for application to very low threshold microlasers as well as very sensitive microsensors, has been recognized only in recent years. This paper presents a review of the field of WGM resonators, which exist in several geometrical structures like cylindrical optical fibers, microspheres, microfiber coils, microdisks, microtoroids, photonic crystal cavities, etc. up to the most exotic structures, such as bottle and bubble microresonators. For the sake of simplicity, the fundaments of WGM propagation and most of the applications will be described only with reference to the most common structure, i.e. microspherical resonators.", "author_names": [ "Giancarlo Cesare Righini", "Yannick Dumeige", "Patrice Feron", "Maurizio Ferrari", "G N Conti", "Davor Ristic", "Silvia Soria" ], "corpus_id": 46449309, "doc_id": "46449309", "n_citations": 208, "n_key_citations": 16, "score": 0, "title": "Whispering gallery mode microresonators: Fundamentals and applications", "venue": "", "year": 2011 }, { "abstract": "In the last fifteen years, quantum confined semiconductor structures (QCSS) have attracted much attention because of their novel properties and their potential for electronic and photonic applications. Electronic and optical properties of QCSS are dominated by the combined effects of quantum statistics and Coulomb interaction. Their response to electromagnetic excitations is determined by a polarization which possesses a time dependent amplitude and phase. Although the phase is a very sensitive probe of microscopic scattering and collision mechanisms, most of ultrafast spectroscopy of heterostructures has concentrated on measuring the amplitude only. Using a combination of time resolved, frequency resolved, and interferometric correlation techniques the author has recently investigated the phase and amplitude of coherent wave mixing (CWM) emission from quantum well structures excited by two ultrashort pulses.<ETX>", "author_names": [ "Daniel S Chemla" ], "corpus_id": 119455411, "doc_id": "119455411", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Dynamics of instantaneous frequency and amplitude of coherent wave mixing in quantum confined semiconductor structures", "venue": "Proceedings of 1994 Nonlinear Optics: Materials, Fundamentals and Applications", "year": 1994 }, { "abstract": "Preface. 1. Fabrication Procedures. Solid Source Molecular Beam Epitaxy J.F. Rochette. Using Gaseous Sources in Molecular Beam Epitaxy C.W. Tu. 2. Fundamentals on Quantum Structures for Electro Optical Devices. Optical Properties of Heterostructures under an Electric Field P. Tronc. The Role of Spontaneous Emission in Laser Diode Operation P. Blood. MBE Growth of (In, Ga)As Self Assembled Quantum Dots for Optoelectronic Applications V.M. Ustinov, et al. Exciton and Magnetoexciton Luminescence in Ge Ge1 x Six Multiple Quantum Well Structures N.G. Kalugin, et al. The Physics of Quantum Well Infrared Detectors E. Rosencher, et al. Semimagnetic Quantum Wells and Superlattices M. Averous. Surface, Leaky and Singular Magnetoplasmons along the Interface of Gyrotropic Semiconductor S.T. Ivanov, et al. Optical and Theoretical Assessment of GaAs Quantum Wells Having Superlattices as Barrier Layers V. Donichev, et al. Anisotropy of Optical Characteristics of Low Dimensional and Bulk Many Valley Semiconductors A. Svizhenko, et al. Hot Hole Effects in Strained Multi Quantum Well Heterostructures Ge/GeSi V.Ya. Aleshkin, et al. Enhancement of Average Velocity of Hot Carriers in Saw Toothed Heterostructure A.B. Kozyrev, V.A. Kozlov. Path Integral Calculation of the Electron Density of States in MIS Structures G. Slavcheva, Y. Yanchev. 3. Nonlinear Optical Devices. Physics and Applications of Exciton Saturation in MQW Structures A. Miller, et al. Interferometer with Nonlinear Frequency Doubling Mirrors as Lossless All Optical Switching Device S. Saltiel, et al. Waveguide Based Devices: Linear and Nonlinear Coupling A.D. Boardman, K. Xie. Waveguide Mach Zehnder Intensity Modulator Produced via Proton Exchange Technology in LiNbO3 S. Tonchev, et al. Evanescent Field Coupling Between a Single Mode Optical Fiber and a Planar Waveguide A. Andreev, et al. 4. Pseudomorphic HETM. Pseudomorphic HETMS: Device Physics and Materials Layer Design T. Grave. Basics of Pseudomorphic HETSM Technology and Numerical Simulation A. Asenov, et al. Index.", "author_names": [ "Minko Balkanski" ], "corpus_id": 137582922, "doc_id": "137582922", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Devices based on low dimensional semiconductor structures", "venue": "", "year": 1996 }, { "abstract": "1. Basic Concepts. 2. Free Carrier Theory. 3. Coulomb Effects. 4. Correlation Effects. 5. Bulk Band Structures. 6. Quantum Wells. 7. Applications. References.", "author_names": [ "Weng W Chow", "Stephan W Koch" ], "corpus_id": 117919512, "doc_id": "117919512", "n_citations": 159, "n_key_citations": 7, "score": 0, "title": "Semiconductor Laser Fundamentals: Physics of the Gain Materials", "venue": "", "year": 1999 } ]

[ { "abstract": "The study of the optimal data rates of high speed channels supported by typical high performance FPGA chips is presented. First, the representative channels are grouped into distinct categories that have drastically dissimilar characteristics. Consequently, the range of the channel operating data rates are expected to be significantly different. Special circuitries of various complexity are often implemented in the transmitters and receivers to mitigate the channel attenuation and enable the link to operate at the desired data rates. This paper attempts to shed a light on the optimal intrinsic channel data rates. Based on the signaling power, receiver sensitivity and the channel frequency responses, the range or optimal signaling rates of the channels are derived for each category. Finally, the paper summarizes the main differences of the channels in terms of characteristics, transceiver complexity, and optimal data rates when the high speed links are implemented in suitable semiconductor technology.", "author_names": [ "Wendemagegnehu T Beyene", "Ashkan Hashemi", "Changwook Yoon", "Hyo-soon Kang", "Xiaoping Liu", "Guang Chen", "Karthik Chandrasekar", "David Greenhill" ], "corpus_id": 53434332, "doc_id": "53434332", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Signaling Analysis and Optimal Channel Data Rates for High Performance FPGA Interfaces", "venue": "2018 IEEE 27th Conference on Electrical Performance of Electronic Packaging and Systems (EPEPS)", "year": 2018 }, { "abstract": "COTS (commercial off the shelf) hard ware using an industry standard Camera Link interface is proposed to accomplish the task of designing, building, assembling, and testing electronics for an airborne spectrometer that would be low cost, but sustain the required data speed and volume. The focal plane electronics were designed to support that hardware standard. Analysis was done to determine how these COTS electronics could be interfaced with space qualified camera electronics. Interfaces available for spaceflight application do not support the industry standard Camera Link interface, but with careful design, COTS EGSE (electronics ground support equipment) including camera interfaces and camera simulators, can still be used. The Camera Link data path is expandable. By adding another pair of interface circuits, and five more LVDS (low voltage differential signaling) pairs (the \"medium\" Camera Link interface) the data rate can be doubled (4,080 Mbps) By adding a third pair of interface circuits and five more LVDS pairs (the \"full\" Camera Link interface) data rates of 64 bits x 85 MHz 5,440 Mbps (over 5 Gbps) can be realized. The 28 bit commercial Camera Link interface is backwards compatible with the 21 bit spacequalified Channel Link interface. With proper circuit design and EGSE programming, the space qualified chip set can be used to implement a compatible Camera Link interface using COTS Camera Link EGSE. COTS EGSE in the form of instrument (camera) simulators is also readily available. This allows easy, early checkout of the EGSE and flight systems. This work was done by David P. Randall and John C. Mahoney of Caltech for NASA's Jet Propulsion Laboratory. For more information, contact [email protected]. NPO46991 Adaptation of the Camera Link Interface for Flight Instrument Applications NASA's Jet Propulsion Laboratory, Pasadena, California", "author_names": [ "Loren P Clare", "Jordan L Torgerson", "Jackson Pang" ], "corpus_id": 107093280, "doc_id": "107093280", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "High Performance CCSDS Encapsulation Service Implementation in FPGA", "venue": "", "year": 2010 }, { "abstract": "Over the past few decades, incessant growth of Internet networking traffic and High Performance Computing (HPC) has led to a tremendous demand for data bandwidth. Digital communication technologies combined with advanced integrated circuit scaling trends have enabled the semiconductor and microelectronic industry to dramatically scale the bandwidth of high loss interfaces such as Ethernet, backplane, and Digital Subscriber Line (DSL) The key to achieving higher bandwidth is to employ equalization technique to compensate the channel impairments such as Inter Symbol Interference (ISI) crosstalk, and environmental noise. Therefore, todayas advanced input/outputs (I/Os) has been equipped with sophisticated equalization techniques to push beyond the uncompensated bandwidth of the system. To this end, process scaling has continually increased the data processing capability and improved the I/O performance over the last 15 years. However, since the channel bandwidth has not scaled with the same pace, the required signal processing and equalization circuitry becomes more and more complicated. Thereby, the energy efficiency improvements are largely offset by the energy needed to compensate channel impairments. In this design paradigm, re thinking about the design strategies in order to not only satisfy the bandwidth performance, but also to improve power performance becomes an important necessity. It is well known in communication theory that coding and signaling schemes have the potential to provide superior performance over band limited channels. However, the choice of the optimum data communication algorithm should be considered by accounting for the circuit level power performance trade offs. In this thesis we have investigated the application of new algorithm and signaling schemes in wireline communications, especially for communication between microprocessors, memories, and peripherals. A new hybrid NRZ/Multi Tone (NRZ/MT) signaling method has been developed during the course of this research. The system level and circuit level analysis, design, and implementation of the proposed signaling method has been performed in the frame of this work, and the silicon measurement results have proved the efficiency and the robustness of the proposed signaling methodology for wireline interfaces. In the first part of this work, a 7.5 Gb/s hybrid NRZ/MT transceiver (TRX) for multi drop bus (MDB) memory interfaces is designed and fabricated in 40 nm CMOS technology. Reducing the complexity of the equalization circuitry on the receiver (RX) side, the proposed architecture achieves 1 pJ/bit link efficiency for a MDB channel bearing 45 dB loss at 2.5 GHz. The measurement results of the first prototype confirm that NRZ/MT serial data TRX can offer an energy efficient solution for MDB memory interfaces. Motivated by the satisfying results of the first prototype, in the second phase of this research we have exploited the properties of multi tone signaling, especially orthogonality among different sub bands, to reduce the effect of crosstalk in high dense wireline interconnects. A four channel transceiver has been implemented in a standard CMOS 40 nm technology in order to demonstrate the performance of NRZ/MT signaling in presence of high channel loss and strong crosstalk noise. The proposed system achieves 1 pJ/bit power efficiency, while communicating over a MDB memory channel at 36 Gb/s aggregate data rate.", "author_names": [ "Kiarash Gharibdoust" ], "corpus_id": 111521523, "doc_id": "111521523", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Hybrid NRZ/Multi Tone Signaling for High Speed Low Power Wireline Transceivers", "venue": "", "year": 2016 }, { "abstract": "Bandwidth demand is exploding due to internet video/TV streaming, Web surfing, file sharing, VoIP, video calling, online gaming, and etc. The bandwidth requirement leads us to develop 400G line card solution for communication systems. 28Gb/s electrical interface can increase port density and reduce power per bit. New heterogeneous SSIT (Stacked Silcon Interconnect Technology) design to implement 28Gb/s SerDes transceivers into an FPGA package will be introduced. The silicon interposer was used in this technology and it includes a significant number of TSVs (Through Silicon Vias) for the high speed signals. It is imperative that the signal path including the interposer is accurately modeled over the high operating frequency range by considering all those requirements before design optimization. Detailed design optimization for interposer has been performed to evaluate optimum design rules by taking into consideration of manufacturability and the TSV's parasitic effects from DC to high frequency, which can cause major performance degradation. A package channel design methodology for 28Gb/s SerDes signal support will be introduced. The package material selection to minimize dielectric loss and trace design to minimize copper/surface roughness loss for package substrate are very important. In addition, the design topologies to minimize signal attenuation loss, reflection loss, crosstalk and power coupling noise will be presented. Package and PCB design co optimization is very important to minimize reflections from solder ball interface. Any single mismatch in the very high speed system can result in the significant closer of the eye diagram. Once full channel analysis has been performed including optimized stacked silicon interposer model on top of low loss package substrate and PCB model, the simulation data is compared to the measured 28Gb/s Eye diagram and showing very good correlation. The proposed optimized channel system enables high performance signaling and great visibility of 28Gb/s Serdes FPGA applications.", "author_names": [ "Namhoon Kim", "D Wu", "Jack Carrel", "Joong-Ho Kim", "P Wu" ], "corpus_id": 45795060, "doc_id": "45795060", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Channel design methodology for 28Gb/s SerDes FPGA applications with stacked silicon interconnect technology", "venue": "2012 IEEE 62nd Electronic Components and Technology Conference", "year": 2012 }, { "abstract": "To enable 28 Gb/s transceiver operation, Xilinx has employed many innovative techniques for circuits, packaging and systems. Virtex(r) 7 HT FPGAs are designed to use Stacked Silicon Interconnect (SSI) technology that relies on an interposer built on low loss package substrate material. Channel loss, reflection loss and crosstalk noise are critical factors in determining system performance at this very high speed. The new concept of SSI in an FPGA device will be introduced. The interposer includes a significant number of TSVs (Through Silicon Vias) for the high speed signals. Technology requirements and manufacturing processes to support 28Gb/s SerDes application will be presented. It is imperative that the signal path including the interposer is accurately modeled over the high frequency operating range by considering all those requirements before design optimization. Detailed design optimization for the interposer has been performed to find optimum design rules by taking into consideration manufacturability and parasitic effects of the TSV's from DC to high frequency, which can cause major performance degradation. We will also introduce a package design methodology for 28Gb/s SerDes signal support. The package material selection to minimize dielectric loss and trace design to minimize copper/surface roughness loss for the package substrate is very important. In addition, the design topologies to minimize signal loss, reflection loss and crosstalk will be presented. Package and PCB design co optimization is very important to minimize reflections from solder ball interface. Any single mismatch in the very high speed system can result in the significant closure of the eye diagram. Once full channel analysis has been performed including the optimized silicon interposer model on top of a low loss package substrate and PCB model, the simulation data is then compared to the measured 28Gb/s eye diagram, showing very good correlation. The proposed optimized channel system enables high performance signaling and great visibility of 28Gb/s SerDes enabled FPGA products.", "author_names": [ "Zhaoyin Daniel Wu" ], "corpus_id": 18615281, "doc_id": "18615281", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Channel Co optimization for 28 Gb s SerDes FPGA Applications with Stacked Silicon Interconnect Technology", "venue": "", "year": 2011 }, { "abstract": "Brain machine interfaces (BMIs) may be used to investigate neural mechanisms or to treat the symptoms of neurological disease and are hence powerful tools in research and clinical practice. Wireless BMIs add flexibility to both types of applications by reducing movement restrictions and risks associated with transcutaneous leads. However, since wireless implementations are typically limited in terms of transmission capacity and energy resources, the major challenge faced by their designers is to combine high performance with adaptations to limited resources. Here, we have identified three key steps in dealing with this challenge: (1) the purpose of the BMI should be clearly specified with regard to the type of information to be processed; (2) the amount of raw input data needed to fulfill the purpose should be determined, in order to avoid over or under dimensioning of the design; and (3) processing tasks should be allocated among the system parts such that all of them are utilized optimally with respect to computational power, wireless link capacity and raw input data requirements. We have focused on step (2) under the assumption that the purpose of the BMI (step 1) is to assess single or multi unit neuronal activity in the central nervous system with single channel extracellular recordings. The reliability of this assessment depends on performance in detection and sorting of spikes. We have therefore performed absolute threshold spike detection and spike sorting with the principal component analysis and fuzzy c means on a set of synthetic extracellular recordings, while varying the sampling rate and resolution, noise level and number of target units, and used the known ground truth to quantitatively estimate the performance. From the calculated performance curves, we have identified the sampling rate and resolution breakpoints, beyond which performance is not expected to increase by more than 1 5% We have then estimated the performance of alternative algorithms for spike detection and spike sorting in order to examine the generalizability of our results to other algorithms. Our findings indicate that the minimization of recording noise is the primary factor to consider in the design process. In most cases, there are breakpoints for sampling rates and resolution that provide guidelines for BMI designers in terms of minimum amount raw input data that guarantees sustained performance. Such guidelines are essential during system dimensioning. Based on these findings we conclude by presenting a quantitative task allocation scheme that can be followed to achieve optimal utilization of available resources.", "author_names": [ "Palmi Thor Thorbergsson", "Martin Garwicz", "Jens Schouenborg", "Anders J Johansson" ], "corpus_id": 27700759, "doc_id": "27700759", "n_citations": 6, "n_key_citations": 2, "score": 0, "title": "Minimizing data transfer with sustained performance in wireless brain machine interfaces.", "venue": "Journal of neural engineering", "year": 2012 }, { "abstract": "Rapid developments in neural interface technology are making it possible to record increasingly large signal sets of neural activity. Various factors such as asymmetrical information distribution and across channel redundancy may, however, limit the benefit of high dimensional signal sets, and the increased computational complexity may not yield corresponding improvement in system performance. High dimensional system models may also lead to overfitting and lack of generalizability. To address these issues, we present a generalized modulation depth measure using the state space framework that quantifies the tuning of a neural signal channel to relevant behavioral covariates. For a dynamical system, we develop computationally efficient procedures for estimating modulation depth from multivariate data. We show that this measure can be used to rank neural signals and select an optimal channel subset for inclusion in the neural decoding algorithm. We present a scheme for choosing the optimal subset based on model order selection criteria. We apply this method to neuronal ensemble spike rate decoding in neural interfaces, using our framework to relate motor cortical activity with intended movement kinematics. With offline analysis of intracortical motor imagery data obtained from individuals with tetraplegia using the BrainGate neural interface, we demonstrate that our variable selection scheme is useful for identifying and ranking the most information rich neural signals. We demonstrate that our approach offers several orders of magnitude lower complexity but virtually identical decoding performance compared to greedy search and other selection schemes. Our statistical analysis shows that the modulation depth of human motor cortical single unit signals is well characterized by the generalized Pareto distribution. Our variable selection scheme has wide applicability in problems involving multisensor signal modeling and estimation in biomedical engineering systems.", "author_names": [ "Wasim Q Malik", "Leigh R Hochberg", "John P Donoghue", "Emery N Brown" ], "corpus_id": 18455898, "doc_id": "18455898", "n_citations": 15, "n_key_citations": 2, "score": 0, "title": "Modulation Depth Estimation and Variable Selection in State Space Models for Neural Interfaces", "venue": "IEEE Transactions on Biomedical Engineering", "year": 2015 }, { "abstract": "Today's designs have grown in size and complexity by orders of magnitude in comparison to common designs of only a few years ago. FPGAs have also grown in size and density, with 100k gate FPGAs now available. Because of this growth in FPGA density, designs that previously required an ASIC implementation may now be targeted to an FPGA. However, schematic based design is no longer the ideal method of design entry when attempting to meet time to market requirements. Hardware Description Languages (HDLs) such as VHDL and Verilog are necessities for high speed design targeting high density FPGAs. Because of the need for HDLs, HDL synthesizers play a vital role in the design process. Moreover, once placeand route of the design has been completed, FPGA level and system level timing verification become critical design paths. This paper analyzes the entire design process required to implement a high complexity, high speed design a Peripheral Component Interface (PCI) Bus Target Controller Interface in a high density FPGA. Selection of a design methodology will be discussed as well as the ramifications of this choice in regards to the selection of a suite of tools for performing design entry and analysis and the selection of the target technology. The design process will be examined and common problems that were encountered will be discussed as well as the implemented solutions. Finally, design performance will be analyzed based on maximum frequency of operation, ease of system level integration and analysis, as well as time and effort required to complete the design process. I. PCI Bus Target Controller Interface Requirements As detailed in [13] a PCI Bus Target Controller Interface has the following critical design parameters at the FPGA level: Maximum clock rate of 33 MHz. Minimum input set up time to clock of 7 ns. Minimum hold time from clock of 0 ns. Maximum clock to signal valid delay of 11 ns. 36 bit parity generation and checking for I/O, memory, and configuration spaces. 36 bit input and output pipelines. 48 PCI bus connections and 70+ back end connections. Full speed burst support in memory space. PCI interrupt support. PCI configuration space registers for device ID, vendor ID, status, command, class code, revision ID, memory base address, I/O base address, interrupt line, and interrupt pin. As detailed in [13] a PCI Bus Target Controller Interface has the following critical design parameters at the system level: AC output drive characteristics defined as I/V curves for minimum and maximum drive current. Maximum input pin capacitance of 10 pF. Maximum leakage current of 70 nA. II. Design Methodology As design complexity and speed increase, the complexity of the targeted FPGA's architecture must also increase. A schematic based design methodology is incapable of supporting this increase in FPGA architectural complexity. Therefore, a language based design methodology was used to implement the PCI Bus Target Controller Interface. Language based design, originally a design methodology reserved for ASIC targets[3] is performed at a higher level of abstraction than schematic based design and is therefore geared toward more complex design solutions. As stated in [2] this method of designing at a higher level of abstraction, also known as top down design, is more efficient than the traditional methodology of bottom up design, where lower implementation levels are designed and verified before connected to the higher levels of the design. Changes to the design are far easier to implement and evaluate at this higher level of abstraction and result in minor implementation changes at the lower levels, therefore decreasing the length of the design cycle. Language based design is more conducive to partitioning of the design into submodules in a hierarchical manner, allowing for more efficient design management[4] Hierarchical design also results in a hierarchy of functions that allow for simulation of submodules and a comp arison of the results with higher level behavioral descriptions. This process yields accurate predictions of a design's performance prior to place and route[2] Finally, HDLs allow for the development of designs that are independent of the target technology. As stated in [7] for high density designs, it is more efficient and error free to create and verify designs at a technologyindependent level. However, through the use of an intelligent synthesizer, technology specific solutions are possible. Many vendors provide technology specific and optimized implementations an intelligent synthesizer will take advantage of these implementations to yield a design that is optimized for area and speed[5] Synthesis tools also allow for the integration of the modeling, verification, and implementation processes. The same HDL code can be used for verification and implementation, reducing code maintenance and the risk of inconsistencies between models[6] III. Selection of the Design Tool Suite Because of the choice of a language based design methodology, a high performance tool suite was required to allow for optimal implementation of the design. The chosen tool suite had to allow for HDL design entry, architectural synthesis, and preand post route simulation. The synthesis tools had to provide architecture specific optimizations and design implementations at the FPGA level as part of the design flow. These architecture specific optimizations and implementations would result in the synthesis of a design that is efficient in its usage of area in the FPGA as well as maximizing the speed capability of the design. At the system level, tools that allow for the evaluation of signal integrity and static timing analysis were a necessity when analyzing board level interconnection delays and cross talk between signals. Automation of the design flow as well as ease of use of the individual point tools was also considered while selecting a suite of tools[1] Finally, the tool suite had to be fully integrated with all FPGA vendor tools to guarantee a smooth design flow. In the past, most language based design was performed in a UNIX environment and targeted toward ASICs. However, due to the decrease in cost and the increase in performance of today's PCs, as well as the availability of vendor placeand route tools for the PC environment, the choice was made to design in the PC environment, necessitating a PC based tool suite that may be used in both the Windows NT and Windows95 operating systems. The tool suite chosen for design development was WorkView Office, provided by Viewlogic Systems, Inc. WorkView Office provides a suite of tools that satisfied the design entry, synthesis, simulation, and automation requirements, both at the FPGA level and the board level. ViewSynthesis was used for synthesis of the HDL design. Digital Fusion was used for all phases of simulation at the FPGA level due to its support of both HDL and gate level simulation. Motive was used for board level static timing analysis and XTK was used for board level signal integrity analysis. Finally, IntelliFlow was used to automate the design flow, allowing for concentration on the design itself rather than on the tool interfaces[1] IV. Selection of the Target Technology FPGA architectural granularity is extremely important in evaluating possible target technologies. Fine grained architectures employ simple transistor level elements while coarsegrained architectures involve multiple transistors implemented in pre wired blocks. Generally, the more fine grained the architecture, the more ASIC like the FPGA[8] The importance of granularity is obvious the more ASIC like architecture will generally yield better synthesized results from the HDL code since language based design was originally created for ASIC targets. Another important factor in selecting a target technology is FPGA density, which is defined in terms of usable gates. Many FPGA vendors list the number of total gates available for a given FPGA. However, the true indication of an FPGA's density is in terms of usable gates. The number of usable gates is determined by the effectiveness of the vendor's place and route tools, and is defined as the percentage of the total gates available that the place and route tools can successfully route. As an FPGA's usable gate count increases, there is a resulting increase in design performance in respect to both routability and speed. I/O capacity is also a deciding trait when choosing an FPGA. While more I/O is always desirable, the obvious tradeoff occurs in board space. Selecting an FPGA with increased I/O capacity results in a corresponding increase in package size and hence the amount of board space required. Normally, the physical size of the FPGA would be an important criteria for device selection. However, no limitation on available board space was given as a design requirement, therefore eliminating the issue of fitting the FPGA into a specified area in the system. In designs where board space is limited, it is important to remember that the I/O capacity of the FPGA is greatly affected by the package type selected. The PCI Bus Target Controller Interface requires 123 I/O pins. On chip RAM is another extremely useful feature available on some FPGAs. On chip RAM has faster access times than off chip RAM and does not require the extra board space for off chip RAM. If on chip RAM is not present, the only available method for implementing RAM within the FPGA is to use the flip flops that implement gate level functions as look up tables (LUTs) in logic elements (LEs) However this underutilizes the LEs and results in poor overall FPGA utilization. Table I lists usable gates, maximum I/O, and on chip RAM bits available for four FPGA vendors. Data is from [8] [9] [10] and [11] and is displayed for equivalent FPGAs that meet the minimum I/O requirement of the PCI Bus Target Controller Interface. Data for the Actel A32200DX, Lucent OR2C15A, and Xilinx XC4013E ar", "author_names": [ "Adam J Elbirt" ], "corpus_id": 16350743, "doc_id": "16350743", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Implementation of a PCI Bus Target Interface in a High Density FPGA", "venue": "", "year": 2002 }, { "abstract": "Data converters are critical elements in communication systems forming bridges between analog transmission media such as fiber optics, microwave, RF, and digital processing blocks like FPGAs and DSPs. System designers often focus on selecting the most appropriate data converters for the application, while much less consideration may be given to the selection of the clock generation devices supplying the data converters. A broad range of clock generators with widely different performance attributes are available. However, without careful consideration of clock generator, phase noise, and jitter performance characteristics, data converter, dynamic range, and linearity performance can be severely impacted. This article discusses the effect of clock generator, phase noise, and jitter on the dynamic range and linearity of data converters (ADCs and DACs) in detail. Theoretical analysis of clock jitter on converter SNR is presented and simulation results are provided using Analog Devices' high performance clock generators. Analog Devices has developed a unique line of high performance clock distribution and clock generation products that enable the system designer to maximize the performance from data converters. The HMC1032LP6GE and the HMC1034LP6GE are SMT packaged clock generators, which are ideal for a wide range of high performance cellular/4G infrastructure, fiber optic, and networking applications, and deliver best in class jitter and industry leading phase noise floor. The HMC987LP5E 1:9 fanout buffer is ideal as a clock driver in critical applications and features an ultralow noise floor of 166 dBc/Hz. Key specifications for these devices are shown in Tables 1 and 2. System Considerations A typical LTE (long term evolution) base station utilizing MIMO (multiple input multiple output) architecture is shown in Figure 1. The architecture consists of multiple transmitters, receivers, and DPD (digital predistortion) feedback paths. Various transmitter/receiver components, such as data converters (ADCs/ DACs) and local oscillators (LO) require low jitter reference clocks to improve performance. Other baseband components also require clock sources of various frequencies. Share on Twitter Share on LinkedIn Email Table 1. Clock Generators Typical Performance Characteristics Part Number Maximum Frequency (MHz) Function Typical Phase Jitter (fs rms) Phase Noise Floor (dBc/Hz) Maximum Reference Frequency (MHz) Typical Power Consumption (W) Figure of Merit (Frac/Int) (dBc/Hz) HMC1032LP6GE 350 High performance clock generator with fractional N PLL and VCO 75 165 350 0.86 227/ 230 HMC1034LP6GE 3000 High performance clock generator with fractional N PLL and VCO 78 165 350 0.86 227/ 230 Table 2. Clock Distribution Products Typical Performance Characteristics Part Number Maximum Clock Rate (GHz) Function Input Output Phase Jitter (12 kHz to 20 MHz) Rise/Fall Time (ps) Channel Skew (ps) Channel Disable Mode Power Supply (V) HMC987LP5E 8 1:9 fanout buffer LVPECL, LVDS, CML, CMOS LVPECL 8 fs rms 65 3.1 Yes 3.3 2 The Impact of Clock Generator Performance on Data Converters The clock source used to achieve interbase station synchronization typically comes from a GPS (global positioning system) or CPRI (common public radio Interface) link. Such a source typically has excellent long term frequency stability; however, it requires frequency translation to the required local reference frequency with excellent short term stability, or jitter. A high performance clock generator, such as the HMC1032LP6GE, performs the frequency translation and provides a low jitter clock signal, which may then be distributed to various base station components. Selecting the optimal clock generator is critical because a suboptimal reference clock contributes to higher LO phase noise, resulting in higher transmit/receive EVM (error vector magnitude) and system SNR (signal to noise ratio) High clock jitter and noise floor also affects data converters by reducing system SNR, and introducing data converter spurious emissions, thereby further reducing the data converter SFDR (spurious free dynamic range) Consequently, a low performance clock source ultimately reduces system capacity and throughput. Clock Generator Specifications While there are various definitions of clock jitter, the most applicable definition in data converter applications is phase jitter, which is specified in time domain units of ps rms or fs rms. Phase jitter (PJBW) is the jitter derived by the integration of the clock signal's phase noise over a specific range of offsets from the carrier and is given by the following equation: fCLK is the frequency of operation; fMIN/fMAX indicate the bandwidth of interest, and S(fCLK) represents the SSB phase noise. The upper and lower limits of the integration bandwidth (fMIN/fMAX) are unique to each application and are set by the relevant spectral content that the design will be sensitive to. A designer's goal then is to choose a clock generator with the lowest integrated noise, or phase jitter in the desired bandwidth. Traditionally, clock generators are characterized by integrating over 12 kHz to 20 MHz, which is the specified requirement for optical communication interfaces, such as SONET. While this may be applicable in some data converter applications, a broader spectrum of integration, particularly extending beyond 20 MHz is usually needed to capture the relevant noise profile of the sample clock for a high speed data converter. When measuring phase noise the noise offsets far from the carrier frequency. For example, the actual clock frequency used for data converter sampling are commonly referred to as far from carrier phase noise. The limit of this noise is usually referred to as the phase noise floor, as shown in Figure 2. This figure shows the actual measurement plot of ADI's HMC1032LP6GE clock generator. The phase noise floor takes on additional importance in data converter applications because of the sensitivity of the converter SNR to broadband noise on its clock input. When designers evaluate options for clock generators, the phase noise floor performance must be considered as a key benchmark.", "author_names": [ "Max Operatinq Frequency", "Max Reference", "" ], "corpus_id": 18022623, "doc_id": "18022623", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "THE IMPACT OF CLOCK GENERATOR PERFORMANCE ON DATA CONVERTERS", "venue": "", "year": 2015 }, { "abstract": "Due to increasing demand for more bandwidth and higher data rates, the design complexity and constraints of high performance digital system have increased rapidly. Apart from the circuit design challenges, high speed interconnects have brought new challenges in signal transmission integrity and timing requirements. It is known that memory play a vital part of high performance digital system and, the feasible data transfer rate from memory is greatly influenced by performance of interconnects between memory and controller. Increase in data transfer rate from memory and decrease in access latency reduce the timing margin available to each component such as memory controller, PHY, memory module and interconnects. Hence, a diligent budgeting of timing requirement for each sub system is essential to achieve better end to end performance. In this paper, timing optimization of interconnects on signal integrity and timing analysis perspective is presented. As a case study an 800 Mbps interface between a dual rank DDR3 memory and Virtex 6 FPGA has been analyzed and validated. The adopted techniques enabled deriving appropriate timing budget for interconnects and ascertain end to end data rate is not degraded due to sub optimal design of interconnects. Further, the analysis also assisted to derive appropriate routing density, trace length matching, and addressing impedance discontinuities, via selection and signal integrity aware routing.", "author_names": [ "Hitesh Sharma", "J Mervin", "David Selvakumar" ], "corpus_id": 10874133, "doc_id": "10874133", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "DDR3 interconnect optimization Signal integrity and timing analysis perspective", "venue": "2015 International Conference on Control, Electronics, Renewable Energy and Communications (ICCEREC)", "year": 2015 } ]

[ { "abstract": "(NOTE: Chapters 3 11 include an Introduction, Historical Development and Basic Concepts, Manufacturing Methods and Equipment, Measurement Methods, Models and Simulation, Limits and Future Trends in Technologies and Models, Summary of Key Ideas, References, and Problems. 1. Introduction and Historical Perspective. Introduction. Integrated Circuits and the Planar Process Key Inventions That Made It All Possible. Semiconductors. Semiconductor Devices. Semiconductor Circuit Families. Modern Scientific Discovery Experiments, Theory and Computer Simulation. The Plan for This Book. 2. Modern CMOS Technology. CMOS Process Flow. 3. Crystal Growth, Wafer Fabrication and Basic Properties of Silicon Wafers. 4. Semiconductor Manufacturing Clean Rooms, Wafer Cleaning and Gettering. 5. Lithography. 6. Thermal Oxidation and the Si/SiO2 Interface. 7. Dopant Diffusion. 8. Ion Implantation. 9. Thin Film Deposition. 10. Etching. 11. Backend Technology.", "author_names": [ "James D Plummer", "Michael D Deal", "Peter B Griffin" ], "corpus_id": 107363121, "doc_id": "107363121", "n_citations": 66, "n_key_citations": 11, "score": 1, "title": "Silicon VLSI Technology: Fundamentals, Practice, and Modeling", "venue": "", "year": 2020 }, { "abstract": "silicon vlsi technology fundamentals practice and modeling is available in our digital library an online access to it is set as public so you can download it instantly. Our books collection hosts in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the silicon vlsi technology fundamentals practice and modeling is universally compatible with any devices to read.", "author_names": [ "Paul Ba 1/4 rger" ], "corpus_id": 63119882, "doc_id": "63119882", "n_citations": 121, "n_key_citations": 11, "score": 0, "title": "Silicon Vlsi Technology Fundamentals Practice And Modeling", "venue": "", "year": 2016 }, { "abstract": "The continued scaling of integrated circuit technologies, along with the increased design complexity, has exacerbated the challenges associated with manufacturability and yield. In today's semiconductor manufacturing, lithography plays a fundamental role in printing design patterns on silicon. However, the growing complexity and variation of the manufacturing process have tremendously increased the lithography modeling and simulation cost. Besides, both the role and cost of resolution enhancement techniques (RETs) now indispensable in the design process have increased. Parallel to these developments are the recent advancements in Machine Learning (ML) which have provided a far reaching data driven perspective for problem solving. In this work, we shed light on the recent Deep Learning (DL) based approaches that have provided a new lens to examine traditional manufacturability and yield challenges. We present lithography modeling and simulation techniques, leveraging advanced learning paradigms, which have demonstrated unprecedented efficiency. Moreover, we demonstrate the role DL can play in advancing RETs by presenting its successful application in assist feature generation. Also critical to yield is the post fabrication wafer map defect analysis step which our work tackles using a novel confidence aware deep learning scheme. This paper further discusses the future prospects of DL based approaches in the scope of circuits manufacturability and yield.", "author_names": [ "Mohamed Baker Alawieh", "Wei Ye", "David Z Pan" ], "corpus_id": 222120249, "doc_id": "222120249", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Re examining VLSI Manufacturing and Yield through the Lens of Deep Learning (Invited Talk)", "venue": "2020 IEEE/ACM International Conference On Computer Aided Design (ICCAD)", "year": 2020 }, { "abstract": "International Federation for Information Processing The IFIP series publishes state of the art results in the sciences and technologies of information and communication. The scope of the series includes: foundations of computer science; software theory and practice; education; computer applications in technology; communication systems; systems modeling and optimization; information systems; computers and society; computer systems technology; security and protection in information processing systems; artificial intelligence; and human computer interaction. Proceedings and post proceedings of referred international conferences in computer science and interdisciplinary fields are featured. These results often precede journal publication and represent the most current research. The principal aim of the IFIP series is to encourage education and the dissemination and exchange of information about all aspects of computing. For more information about the 300 other books in the IFIP series, please visit www.springer.com. For more information about IFIP, please visit www.ifip.org.", "author_names": [ "Ricardo Reis", "Adam Osseiran", "H Pfleiderer" ], "corpus_id": 63302000, "doc_id": "63302000", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "VLSI SoC: From Systems to Silicon IFIP TC10/ WG 10.5 Thirteenth International Conference on Very Large Scale Integration of System on Chip VLSI SoC2005", "venue": "", "year": 2007 }, { "abstract": "After dominating the electronics industry for decades, silicon is on the verge of becoming the material of choice for the photonics industry: the traditional stronghold of III V semiconductors. Stimulated by a series of recent breakthroughs and propelled by increasing investments by governments and the private sector, silicon photonics is now the most active discipline within the field of integrated optics. This paper provides an overview of the state of the art in silicon photonics and outlines challenges that must be overcome before largescale commercialization can occur. In particular, for realization of integration with CMOS very large scale integration (VLSI) silicon photonics must be compatible with the economics of silicon manufacturing and must operate within thermal constraints of VLSI chips. The impact of silicon photonics will reach beyond optical communication its traditionally anticipated application. Silicon has excellent linear and nonlinear optical properties in the midwave infrared (IR) spectrum. These properties, along with silicon's excellent thermal conductivity and optical damage threshold, open up the possibility for a new class of mid IR photonic devices. Photonic band gap (PBG) materials are periodic dielectric structures that forbid propagation of electromagnetic waves in a certain frequency range. They are able to engineer the most fundamental properties of electromagnetic waves, such as the laws of refraction, diffraction and emission of light from atoms. Such PBG materials not only open up a variety of possible applications, but also give rise to new physics. Unlike electronic micro cavity, optical waveguides in a PBG microchip can simultaneously conduct hundreds of wavelength channels of information in a three dimensional circuit path. The thesis starts with the numerical modeling techniques for modeling as well as simulation of photonic crystal designs are introduced. The modeling techniques include finite difference time domain (FDTD) method and Plane Wave Expansion (PWE) method. The FDTD method has been represented in context to modal and polarization properties of the photonic design and PWE method has been represented in context to band gap analysis of the designed photonic structure.", "author_names": [ "Hem Pushp Mittal", "Sanjay Sharma" ], "corpus_id": 208071479, "doc_id": "208071479", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Performance Analysis and Evaluation of Photonic Waveguides for Multiprocessor Communications A thesis submitted in partial fulfillment of the requirements for the award of degree of Master of Technology in VLSI Design CAD Submitted By:", "venue": "", "year": 2011 }, { "abstract": "Semiconducting carbon nanotubes (CNTs) have gained immense popularity as possible successors to silicon as the channel material for ultra high performance field effect transistors. On the other hand, their metallic counterparts have often been regarded as ideal interconnects for the future technology generations. Owing to their high current densities and increased reliability, metallic single walled CNTs (SWCNTs) have been of fundamental research both in theory as well as experiments. Metallic CNTs have been modeled for RF applications using an LC model. In this paper, we present an efficient circuit compatible RLC model for metallic SWCNTs, and analyze the impact of SWCNTs on the performance of ultra scaled digital VLSI design.", "author_names": [ "Arijit Raychowdhury", "Kaushik Roy" ], "corpus_id": 17043708, "doc_id": "17043708", "n_citations": 17, "n_key_citations": 3, "score": 0, "title": "Modeling and analysis of carbon nanotube interconnects and their effectiveness for high speed VLSI design", "venue": "4th IEEE Conference on Nanotechnology, 2004.", "year": 2004 }, { "abstract": "Future collider experiments are typically motivated by the search for new particles and precision measurements of physical observables. The goal is to find deviations from existing theories. In practice, this requires advances towards higher luminosities at higher collision energies, finally resulting in a more difficult experimental environment. At the same time, more precise measurements are required. One such collider is the high luminosity upgrade of the LHC (HL LHC) that is planned to start operation in 2026. Compared to LHC, the number of simultaneous collisions (pile up) will increase by roughly a factor four and the radiation exposure of the detectors will be an order of magnitude larger than for LHC. Another proposed collider is the Compact Linear Collider (CLIC) that would provide electronpositron collisions at a centre of mass energy of up to 3TeV. As the collision partners are fundamental particles, the initial state and energy are well known. This allows for precision measurements of Higgs and Top quark observables, including a wide variety of measurements that are particularly sensitive to physics beyond the standard model. Here, the detector is required to deliver an unprecedented precision on the measurement of jet energy, impact parameter and particle momentum. For both colliders and their associated experiments, silicon detectors play an essential role in meeting the detection requirements. For CLIC, the desired momentum resolution together with the flavour tagging performance will require a vertex detector with a spatial resolution of around 3 mm and a time resolution better than 5 ns, all at a material budget of only 0.2%X0 per layer. This can be achieved by using thin silicon pixel sensors of around 50mm thickness. The design of the CLIC calorimeter is driven by the need of an unprecedented jet energy resolution. To achieve this, CLIC will employ a highly granular sampling calorimeter optimised for Particle Flow techniques. Silicon pad sensors will be used as active material in the electromagnetic calorimeter due to their compactness, operational stability, excellent signal to noise ratio and good segmentation properties. More recently, the CMS collaboration has decided to adopt a similar concept in the upgrade of their endcap calorimeters for the HL LHC phase, a project commonly called HGCAL. Here, the reasoning to use silicon as active calorimeter material is however broader. It is additionally driven by the need for radiation hardness and precise time stamping for pile up mitigation. In this work, the role of silicon detectors in the CLIC vertex detector as well as the calorimeters for", "author_names": [ "Florian Michael Pitters" ], "corpus_id": 211029459, "doc_id": "211029459", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Silicon Detector Technologies for Future Particle Collider Experiments", "venue": "", "year": 2019 }, { "abstract": "The ability to carry out signal processing, classification, recognition, and computation in artificial spiking neural networks (SNNs) is mediated by their synapses. In particular, through activity dependent alteration of their efficacies, synapses play a fundamental role in learning. The mathematical prescriptions under which synapses modify their weights are termed synaptic plasticity rules. These learning rules can be based on abstract computational neuroscience models or on detailed biophysical ones. As these rules are being proposed and developed by experimental and computational neuroscientists, engineers strive to design and implement them in silicon and en masse in order to employ them in complex real world applications. In this paper, we describe analog very large scale integration (VLSI) circuit implementations of multiple synaptic plasticity rules, ranging from phenomenological ones (e.g. based on spike timing, mean firing rates, or both) to biophysically realistic ones (e.g. calcium dependent models) We discuss the application domains, weaknesses, and strengths of various representative approaches proposed in the literature, and provide insight into the challenges that engineers face when designing and implementing synaptic plasticity rules in VLSI technology for utilizing them in real world applications.", "author_names": [ "Mostafa Rahimi Azghadi", "Nicolangelo Iannella", "Said F Al-Sarawi", "G Indiveri", "Derek Abbott" ], "corpus_id": 12893629, "doc_id": "12893629", "n_citations": 99, "n_key_citations": 6, "score": 0, "title": "Spike Based Synaptic Plasticity in Silicon: Design, Implementation, Application, and Challenges", "venue": "Proceedings of the IEEE", "year": 2014 }, { "abstract": "The thermal environment in VLSI circuits is characterized by the existence of both small and isolated heat sources near the channel region and a vast volume (e.g. substrate) serving as the heat conduction media. The presence of a buried oxide layer in Silicon on Insulator technology introduces an additional thermal barrier between the device and Si substrate. The modeling and simulation of such situations are usually handled with either element based simulations (e.g. finite element methods, lumped element methods) or direct methods based on integral transform. In practice neither approach can maintain both accuracy and efficiency at the same time. We have developed a new methodology for the simulation of the thermal behavior of high density integrated circuits at various levels of complexity. It treats the structured thermal conduction media hierarchically and thus is capable of relating thermal behaviors over a wide range of length scales. As a demonstration this methodology is applied to model heat conduction and self heating effects in SOI technology. Compared to the traditional element based numerical method used to solve the Laplace equation, out method greatly reduces the number of nodes and the computing time while maintaining accuracy.", "author_names": [ "Kai Xiu", "Mark B Ketchen" ], "corpus_id": 44305961, "doc_id": "44305961", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Hierarchical thermal modeling for SOI technology", "venue": "Twentieth Annual IEEE Semiconductor Thermal Measurement and Management Symposium (IEEE Cat. No.04CH37545)", "year": 2004 }, { "abstract": "Semiconducting carbon nanotubes (CNTs) have gained immense popularity as possible successors to silicon as the channel material for ultrahigh performance field effect transistors (FETs) On the other hand, their metallic counterparts have often been regarded as ideal interconnects for future technology generations. Owing to their high current densities and increased reliability, metallic single walled CNTs (SWCNTs) have been subjects of fundamental research, both in theory, as well as experiments. Metallic CNTs have been modeled for radio frequency (RF) applications using a transmission line model. In this paper, we present an efficient circuit compatible RLC model for metallic SWCNTs, and analyze the impact of SWCNTs on the performance of ultrascaled digital very large scale integration (VLSI) design.", "author_names": [ "Arijit Raychowdhury", "Kaushik Roy" ], "corpus_id": 11249569, "doc_id": "11249569", "n_citations": 187, "n_key_citations": 11, "score": 0, "title": "Modeling of metallic carbon nanotube interconnects for circuit simulations and a comparison with Cu interconnects for scaled technologies", "venue": "IEEE Transactions on Computer Aided Design of Integrated Circuits and Systems", "year": 2006 } ]

[ { "abstract": "Pulse package oscillations in broad area semiconductor lasers subjected to short optical feedback are experimentally observed. The pulse package oscillation consists of a frequency component that corresponds to an external optical feedback loop with an envelop of periodic low frequency fluctuations. However, the periodicity induced by optical feedback does not always improve the time averaged beam profiles of the laser oscillations. We also investigated time averaged near field beam profiles in relation with the optical feedback dynamics.", "author_names": [ "Akira Takeda", "Rui Shogenji", "Junji Ohtsubo" ], "corpus_id": 55639714, "doc_id": "55639714", "n_citations": 14, "n_key_citations": 3, "score": 1, "title": "Dynamics and pulse package oscillations in broad area semiconductor lasers with short optical feedback", "venue": "", "year": 2012 }, { "abstract": "ABSTRACT This paper reports on the processing of aluminium melt by pulse magneto oscillation (PMO) technology. The melt is divided into five layers using a layered isolation device and, after grinding and corrosion, the refining effects of equiaxed crystals are observed to decrease from the centre outwards. The electromagnetic force and flow velocity of the melt were simulated using the ANSYS package, and found to decrease in the same manner as crystal size; i.e. from the centre outwards. It was also found that the melt, treated by PMO, possessed an optimum characteristic length at which the flow velocity reaches a maximum value, thus improving the refining effect of the solidification structure of the melt.", "author_names": [ "Shumin Cheng", "Yuyi Zhong", "Zhishuai Xu", "Ning Pei", "Qi-jie Zhai", "Yongyong Gong" ], "corpus_id": 139682463, "doc_id": "139682463", "n_citations": 4, "n_key_citations": 0, "score": 1, "title": "Effect of flow on solidification structure of pure aluminium under pulse magneto oscillation", "venue": "", "year": 2018 }, { "abstract": "In this article, a transfer function based modelling is proposed to investigate voltage oscillation phenomena, i.e. over voltage at the motor terminal, associated with pulse width modulation (PWM) inverter fed motor drives with long feeding cables. As such, the long feeding cable is assumed to be a distortionless transmission line; then, a bounce diagram and time harmonic method are utilised to derive a simple model with a minimum computational burden that is easy to realise using the Matlab/Simulink software package. Furthermore, the model takes account of the inverter output and the motor terminal filters, which are commonly used to suppress the motor terminal over voltage. The model accuracy is verified by a comparison with the circuit oriented software, OrCAD/PSpice, simulation results.", "author_names": [ "Sang-Choel Lee", "Ju H Park" ], "corpus_id": 59421773, "doc_id": "59421773", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Transfer function based modelling for voltage oscillation phenomena in PWM motor drives with long feeding cables", "venue": "", "year": 2010 }, { "abstract": "Although external cavity feedback with a grating is widely used to achieve a tunable high power narrow linewidth broad area diode laser (BAL) system, the dynamics of such a system is seldom studied. In this paper, the temporal dynamics of a tunable high power green external cavity diode laser system based on a GaN BAL and Littrow external cavity is investigated experimentally. The regular pulse package oscillation (PPO) is observed just above the threshold. The oscillating period of the pulse package decreases with the increasing injected current. As the current increases further, the pulse package oscillates irregularly, and finally changes to a chaotic state. The PPO is observed, for the first time to our knowledge, in a BAL with an external cavity grating feedback.", "author_names": [ "Mingjun Chi", "Ole Bjarlin Jensen", "Anders Kragh Hansen", "Paul Michael Petersen" ], "corpus_id": 125560883, "doc_id": "125560883", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Dynamics of a green high power tunable external cavity broad area GaN diode laser", "venue": "", "year": 2018 }, { "abstract": "An impulse measurement device and analysis package was conceived, designed, constructed, tested, and demonstrated to be capable of: measuring nanoNewton seconds to milliNewton seconds of impulse due to laser ablation; being transported as carry on baggage; set up and tear down times of less than an hour; target exchange times of less than two minutes (targets can be ablated at multiple positions for thousands of shots) measurements in air and in vacuum; error of just a few percent; repeatability over a wide range of potential systematic error sources; and time between measurements, including ring down and analysis, of less than 30 seconds. The instrument consists of a cantilever (i.e. leaf spring) whose time dependent displacement/oscillation is measured and analyzed to determine the impulse imparted by a laser pulse to a target. These shapes are readily/commercially available, and any target material can be used, provided it can be fashioned in the form of a cantilever, or as a coating/film/tape, suita.", "author_names": [ "Kevin P Kremeyer", "J L Lapeyre", "Steven Hamann" ], "corpus_id": 55971068, "doc_id": "55971068", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Compact And Robust Laser Impulse Measurement Device, With Ultrashort Pulse Laser Ablation Results", "venue": "", "year": 2008 }, { "abstract": "An impulse measurement device and analysis package was conceived, designed, constructed, tested, and demonstrated to be capable of: measuring nanoNewton seconds to milliNewton seconds of impulse due to laser ablation; being transported as carry on baggage; set up and tear down times of less than an hour; target exchange times of less than two minutes (targets can be ablated at multiple positions for thousands of shots) measurements in air and in vacuum; error of just a few percent; repeatability over a wide range of potential systematic error sources; and time between measurements, including ring down and analysis, of less than 30 seconds. The instrument consists of a cantilever (i.e. leaf spring) whose time dependent displacement/oscillation is measured and analyzed to determine the impulse imparted by a laser pulse to a target. These shapes are readily/commercially available, and any target material can be used, provided it can be fashioned in the form of a cantilever, or as a coating/film/tape, suitable for mounting on a cantilever of known geometry. The instrument was calibrated both statically and dynamically, and measurements were performed on brass, steel, and Aluminum, using laser pulses of ~7ns, ~500ps, and ~500fs. The results agree well with those published in the literature, with surface effects, atmosphere, and pre /post pulses demonstrating interesting effects and indicating areas for further study. In addition to exploring space propulsion applications, measurements were performed to explore the strong beneficial effects of depositing lines of energy ahead of supersonic and hypersonic vehicles. This deposition creates a low density channel, through which a vehicle can travel with dramatically reduced drag. Temperature and pressure are both also reduced on the front surfaces of the vehicle, while density and pressure are increased at the vehicle base. When applied off center, this technique can be used to control the vehicle, employing the entire body as the control surface and eliminating the need for actuators. Numerical results for drag reduction, temperature reduction, and control forces are indicated here.", "author_names": [ "Kevin P Kremeyer" ], "corpus_id": 109912743, "doc_id": "109912743", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Ultrashort pulse lasers applied to propulsion/control in space and atmospheric flight", "venue": "High Power Laser Ablation", "year": 2008 }, { "abstract": "Different dynamic behaviors, such as regular pulse package oscillation, irregular pulse package oscillation, and chaos are observed in a green high power broad area GaN diode laser system with a grating external cavity feedback.", "author_names": [ "Mingjun Chi", "Ole Bjarlin Jensen", "Anders Kragh Hansen", "Paul Michael Petersen" ], "corpus_id": 139701970, "doc_id": "139701970", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Dynamics of a green high power tunable broad area GaN diode laser with external cavity feedback", "venue": "", "year": 2018 }, { "abstract": "The temporal dynamics of a broad area diode laser with lateral mode selected long cavity feedback is studied experimentally. Different dynamics are observed when different lateral modes are selected. When the feedback mirror is aligned perfectly and high order modes are selected, in most of the cases, the output of the laser shows a periodic oscillation corresponding to a single roundtrip external cavity loop, but the dynamic behavior disappears in some case; when the zero order lateral mode is selected, periodic oscillation corresponding to a double roundtrip external cavity loop is observed. When the feedback mirror is aligned non perfectly, pulse package oscillation is observed, for the first time to our knowledge, in a diode laser with long cavity feedback.", "author_names": [ "Mingjun Chi", "Paul Michael Petersen" ], "corpus_id": 122474437, "doc_id": "122474437", "n_citations": 7, "n_key_citations": 3, "score": 0, "title": "Dynamics of a broad area diode laser with lateral mode selected long cavity feedback", "venue": "", "year": 2014 }, { "abstract": "The CoRoT evolution and seismic tools activity. ASTEC the Aarhus STellar Evolution Code. The FRANEC stellar evolutionary code. YREC: the Yale rotating stellar evolution code. The Geneva stellar evolution code. The Toulouse Geneva Evolution Code (TGEC) CESAM: a free code for stellar evolution calculations. The STAROX stellar evolution code. CLES, Code Liegeois d'Evolution Stellaire. The ATON 3.1 stellar evolutionary code. GARSTEC the Garching Stellar Evolution Code. PULSE: a finite element code for solving adiabatic nonradial pulsation equations. ADIPLS the Aarhus adiabatic oscillation package. Porto Oscillation Code (posc) Granada oscillation code (GraCo) NOSC: Nice OScillations Code. The OSCROX stellar oscillaton code. The Liege Oscillation code. filou oscillation code. LNAWENR linear nonadiabatic nonradial waves. Reference grids of stellar models and oscillation frequencies. Grids of stellar evolution models for asteroseismology (cesam posc) Grids of stellar models and frequencies with CLES LOSC. CoRoT/ESTA TASK 1 and TASK 3 comparison of the internal structure and seismic properties of representative stellar models. FRANEC versus CESAM predictions for selected CoRoT ESTA task 1 models. Thorough analysis of input physics in CESAM and CLES codes. Inter comparison of the g f and p modes calculated using different oscillation codes for a given stellar model. Concluding remarks and perspectives on the evolution and seismic tools activity (ESTA) of the CoRoT community.", "author_names": [ "Mario J P F G Monteiro" ], "corpus_id": 118783954, "doc_id": "118783954", "n_citations": 10, "n_key_citations": 1, "score": 0, "title": "Evolution and seismic tools for stellar astrophysics", "venue": "", "year": 2009 }, { "abstract": "Asymptotic and numerical methods are used to highlight different types of dynamical behaviors that occur for the motion of a localized spike type solution to the singularly perturbed Gierer Meinhardt and Schnakenberg reaction diffusion models in a one dimensional spatial domain. Depending on the parameter range in these models, there can either be a slow evolution of a spike toward the midpoint of the domain, a sudden oscillatory instability triggered by a Hopf bifurcation leading to an intricate temporal oscillation in the height of the spike, or a pulse splitting instability leading to the creation of new spikes in the domain. Criteria for the onset of these oscillatory and pulse splitting instabilities are obtained through asymptotic and numerical techniques. A moving mesh numerical method is introduced to compute these different behaviors numerically, and results are compared with corresponding results computed using a method of lines based software package.", "author_names": [ "Wentao Sun", "Tao Tang", "Michael Jeffrey Ward", "Juncheng Wei" ], "corpus_id": 17016019, "doc_id": "17016019", "n_citations": 15, "n_key_citations": 2, "score": 0, "title": "Numerical Challenges for Resolving Spike Dynamics for Two One Dimensional Reaction Diffusion Systems", "venue": "", "year": 2003 } ]

[ { "abstract": "Silicon crystallized in the usual cubic (diamond) lattice structure has dominated the electronics industry for more than half a century. However, cubic silicon (Si) germanium (Ge) and SiGe alloys are all indirect bandgap semiconductors that cannot emit light efficiently. The goal 1 of achieving efficient light emission from group IV materials in silicon technology has been elusive for decades 2 6 Here we demonstrate efficient light emission from direct bandgap hexagonal Ge and SiGe alloys. We measure a sub nanosecond, temperature insensitive radiative recombination lifetime and observe an emission yield similar to that of direct bandgap group III V semiconductors. Moreover, we demonstrate that, by controlling the composition of the hexagonal SiGe alloy, the emission wavelength can be continuously tuned over a broad range, while preserving the direct bandgap. Our experimental findings are in excellent quantitative agreement with ab initio theory. Hexagonal SiGe embodies an ideal material system in which to combine electronic and optoelectronic functionalities on a single chip, opening the way towards integrated device concepts and information processing technologies. A hexagonal (rather than cubic) alloy of silicon and germanium that has a direct (rather than indirect) bandgap emits light efficiently across a range of wavelengths, enabling electronic and optoelectronic functionalities to be combined on a single chip.", "author_names": [ "Elham M T Fadaly", "Alain Dijkstra", "Jens Rene Suckert", "Dorian Ziss", "Marvin A J van Tilburg", "Chenyang Mao", "Yizhen Ren", "Victor T van Lange", "Ksenia Korzun", "Sebastian Kolling", "Marcel A Verheijen", "David Busse", "Claudia Rodl", "Jurgen Furthmuller", "Friedhelm Bechstedt", "J Stangl", "Jonathan J Finley", "Silvana Botti", "Jos E M Haverkort", "Erik P A M Bakkers" ], "corpus_id": 207870211, "doc_id": "207870211", "n_citations": 79, "n_key_citations": 1, "score": 1, "title": "Direct bandgap emission from hexagonal Ge and SiGe alloys", "venue": "Nature", "year": 2020 }, { "abstract": "Silicon Germanium in a hexagonal crystal structure is a candidate material for a direct band gap group IV semiconductor that can be integrated into the CMOS process. It has recently been synthesized as a crystalline shell grown epitaxial around a nanowire core of hexagonal Gallium Phosphide. In order to study the optical properties of this newly generated material and evaluate its potential for building optical devices it is necessary to grow defect and impurity free hexagonal Silicon Germanium. Impurity detection and mapping in nano structures is however challenging as most bulk and thin film characterization methods cannot be used. Here we show that Atom Probe Tomography can be used to map the impurities in hexagonal shells of Silicon Germanium and Silicon. This will allow to optimize growth of hexagonal Silicon Germanium nanocrystals towards impurity free, optically active crystals.", "author_names": [ "Sebastian Koelling", "Rianne Plantenga", "Hakon Ikaros T Hauge", "Yizhen Ren", "Ang Li", "Marcel A Verheijen", "Sonia Conesa Boj", "Simone Assali", "Pm Paul Koenraad", "Erik P A M Bakkers" ], "corpus_id": 138073195, "doc_id": "138073195", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Impurity and defect monitoring in hexagonal Si and SiGe nanocrystals", "venue": "", "year": 2016 }, { "abstract": "Contributors. Preface. Gallium Nitride (GaN) (V. Bougrov, et al. Aluminum Nitride (AIN) (Y. Goldberg) Indium Nitride (InN) (A. Zubrilov) Boron Nitride (BN) (S. Rumyantsev, et al. Silicon Carbide (SiC) (Y. Goldberg, et al. Silicon Germanium (Si 1 xGe x) (F. Schaffler) Appendix 1: Basic Physical Constants. Appendix 2: Periodic Table of the Elements. Appendix 3: Rectangular Coordinates for Hexagonal Crystal. Appendix 4: The First Brillouin Zone for Wurtzite Crystal. Appendix 5: Zinc Blende Structure. Appendix 6: The First Brillouin Zone for Zinc Blende Crystal. Additional References.", "author_names": [ "M E Levinshtein", "Sergey Rumyantsev", "Michael S Shur" ], "corpus_id": 136897631, "doc_id": "136897631", "n_citations": 1416, "n_key_citations": 52, "score": 0, "title": "Properties of advanced semiconductor materials GaN, AlN, InN, BN, SiC, SiGe", "venue": "", "year": 2001 }, { "abstract": "In this paper, we study the potentialities of SiGe as a photonic crystal via 2D and 3D simulation of photonic band gap (PBG) at the optical communication wavelength (1.55 mm) according to its chemical composition and a variety of structures geometry. Particularly, we are interested in the hexagonal and Yablonovite structures simulations. Results show that for low germanium content in silicon both the existence and the PBG width are strongly related to the geometrical structure parameters in terms of holes radius and their periodicities.", "author_names": [ "M R Beghoul", "Hachemi Bouridah", "F Meriche", "Alexis P A Fischer", "A Boudrioua", "Noureddine Boutaoui" ], "corpus_id": 135650053, "doc_id": "135650053", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Theoretical Study of Photonic Band Gap in the SiGe", "venue": "", "year": 2011 }, { "abstract": "We present a method to obtain a dense array of well organized SiGe quantum dots in Si nanopillars on a large substrate area by using a PS b PMMA block copolymer template. First, the 2D order of the template is evaluated using a pair correlation function and a bond orientational correlation function. It is shown that the holes contained in the polystyrene template form a structure presenting a hexatic order. This template is then used to fabricate the nanopillars using the following method: in a first step, the copolymer template serves as a deposition mask to fabricate a hexagonal array of Pt dots. In a second step, the Pt dot pattern is transferred to an alternation of Si and SiGe layers on a silicon substrate with an anisotropically etching using Cl2/O2 plasma.", "author_names": [ "Karim Aissou", "Thierry Baron", "M Kogelschatz", "Martien I Den Hertog", "J -L Rouviere", "Jean-Michel Hartmann", "Bernard Pelissier" ], "corpus_id": 98316978, "doc_id": "98316978", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "Fabrication of Well Organized and Densely Packed Si Nanopillars Containing SiGe Nanodots by Using Block Copolymer Templates", "venue": "", "year": 2008 }, { "abstract": "Summary form only given. Light emission from Si, would allow integration of electronic and optical functionality in the main electronics platform technology, but this has been impossible due to the indirect band gap of Si. This talk will discuss 2 different approaches, using unique properties of nanowires, to realize light emission from Si based compounds. In the first route, the paper focuses on the fabrication of defect free GeSn compounds. The growth mechanism is discussed, the structural properties are investigated by electron microscopy and atom probe tomography and the temperature dependent optical properties are studied. The second route concentrates on Si and Ge with a different crystal structure. Here, crystal structure transfer is employed, in which wurtzite GaP is used as a template to epitaxially grow SiGe compounds with the hexagonal crystal structure. With this method, defect free hexagonal SiGe shells and branches with tunable Ge concentration are gorwn. The structural and optical properties of these new crystal phases will be discussed. The author believes that these new 3 dimensional epitaxial nanostructures have great potential to integrate optical functionality in Si technology.", "author_names": [ "Erik P A M Bakkers", "Hakon Ikaros T Hauge", "A Li", "Simone Assali", "Alain Dijkstra", "R Tucker", "Y Ren", "Sonia Conesa-Boj", "Marcel A Verheijen" ], "corpus_id": 22294933, "doc_id": "22294933", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "New opportunities with nanowires", "venue": "2016 IEEE Photonics Society Summer Topical Meeting Series (SUM)", "year": 2016 }, { "abstract": "Embodiment of the invention provides a method of forming a nano contact configuration, using the method of manufacturing a semiconductor device which includes a semiconductor device and nanostructures. A method of forming a nanostructure may include forming an insulating layer and a nanostructure formed on the insulating layer. The insulating layer may have a crystalline structure. The insulating layer may include an insulating two dimensional (2D) material. The insulating material may comprise 2D hexagonal boron nitride (h BN) The insulating layer may be formed on the catalyst metal layer. The nanostructures may comprise silicon (Si) germanium (Ge) and at least one of SiGe. Nanostructures may comprise at least one nanowire.", "author_names": [ "" ], "corpus_id": 139682618, "doc_id": "139682618", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A method of forming a nanostructure, a method of manufacturing a semiconductor device and a semiconductor device", "venue": "", "year": 2016 }, { "abstract": "It is disclosed with respect to a semiconductor device including a process for producing a nanostructure and a method for forming a semiconductor device, and applying them nanostructure. Disclosed nanostructure forming method may include the steps of forming the nano structure on the insulating layer forming the insulating layer. The insulating layer can have a crystalline structure. The insulating layer may include a two dimensional insulating material (2D material) The two dimensional insulating material may include a h BN (hexagonal boron nitride) The insulating layer can be formed on the catalyst metal. The nanostructure may include at least one of Si, Ge, and SiGe. The nanostructure may include at least one nanowire (nanowire)", "author_names": [ "" ], "corpus_id": 140499649, "doc_id": "140499649", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Method of forming nanostructure, method of manufacturing semiconductor device using the same and semiconductor device including nanostructure", "venue": "", "year": 2015 }, { "abstract": "The pressure behavior of an amorphous Si rich SiGe alloy (a SixGe1 x, x 0.75) has been investigated up to about 30 GPa, by a combination of Raman spectroscopy, x ray absorption spectroscopy, and x ray diffraction measurements. The trends of microscopic structural properties and of the Raman active phonon modes are presented in the whole pressure range. Nucleation of nanocrystalline alloy particles and metallization have been observed above 12 GPa, with a range of about 2 GPa of coexistence of amorphous and crystalline phases. Transformations from the amorphous tetrahedral, to the crystalline tetragonal (b Sn) and to the simple hexagonal structures have been observed around 13.8 and 21.8 GPa. The recovered sample upon depressurization, below about 4 GPa, shows a local structure similar to the as deposited one. Inhomogeneities of the amorphous texture at the nanometric scale, probed by high resolution transmission electron microscopy, indicate that the recovered amorphous sample has a different ordering at this scale, and therefore the transformations can not be considered fully reversible. The role of disordered grain boundaries at high pressure and the possible presence of a highdensity amorphous phase are discussed.", "author_names": [ "F Coppari", "Alain Polian", "Nicolas Menguy", "Angela Trapananti", "A Congeduti", "Matt Newville", "Vitali B Prakapenka", "Y Choi", "E Principi", "Andrea Di Cicco" ], "corpus_id": 121082400, "doc_id": "121082400", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Pressure induced transformations in amorphous Si Ge alloy", "venue": "", "year": 2012 }, { "abstract": "Abstract Cubic lanthanide sesquioxides consisting of cations with an atom radius larger that promethium could be used as a buffer layer for growth of semiconductors with a cubic structure (Ge, GaAs or SiGe) on Si due to the close matching of a lattice constant between the oxides and the semiconductors. However, the oxides have a stable hexagonal structure at temperatures higher than 600 degC, which is typical for the epitaxy process. According to our ab initio density functional theory calculations, energy of molecular unit of hexagonal lanthanum oxide is lower than that of the cubic structure by 127 meV. In this paper, we demonstrate epitaxial stabilization of pseudomorphic cubic structure of lanthanum oxide grown on a cubic template. The oxide layer can serve as a buffer for growth of Ge or GaAs layers on Si substrate. On the other hand, gadolinium oxide, which according to many studies has a stable cubic structure, was grown on hexagonal GaN. The single crystal monoclinic Gd 2 O 3 could be used as a gate dielectric layer for GaN based electronic devices.", "author_names": [ "Rytis Dargis", "Andrew G Clark", "Erdem Arkun", "Radek Roucka", "Robin Smith", "Alexander A Demkov", "Michael Lebby" ], "corpus_id": 95821906, "doc_id": "95821906", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Growth and application of epitaxial heterostructures with polymorphous rare earth oxides", "venue": "", "year": 2013 } ]

[ { "abstract": "Power semiconductor devices are key components in power conversion systems. Silicon carbide (SiC) has received increasing attention as a wide bandgap semiconductor suitable for high voltage and low loss power devices. Through recent progress in the crystal growth and process technology of SiC, the production of medium voltage (600?1700 V) SiC Schottky barrier diodes (SBDs) and power metal?oxide?semiconductor field effect transistors (MOSFETs) has started. However, basic understanding of the material properties, defect electronics, and the reliability of SiC devices is still poor. In this review paper, the features and present status of SiC power devices are briefly described. Then, several important aspects of the material science and device physics of SiC, such as impurity doping, extended and point defects, and the impact of such defects on device performance and reliability, are reviewed. Fundamental issues regarding SiC SBDs and power MOSFETs are also discussed.", "author_names": [ "Tsunenobu Kimoto" ], "corpus_id": 46180127, "doc_id": "46180127", "n_citations": 493, "n_key_citations": 9, "score": 1, "title": "Material science and device physics in SiC technology for high voltage power devices", "venue": "", "year": 2015 }, { "abstract": "This paper presents a critical evaluation of the performance capabilities of various wide bandgap semiconductors for high power and high frequency unipolar electronic devices. Seven different figures of merit have been analyzed. Theoretical calculations show that besides diamond and SiC, compounds like AlN, GaN, InN, and ZnO, and the intermetallics (Ga/sub x/In/sub 1 x/N, Al/sub x/In/sub 1 x/N, Al/sub x/Ga/sub 1 x/N, and (AlN)/sub x/(SiC)/sub 1 x/ offer several orders of magnitude improvement in the on resistance and in the potential for successful operation at higher temperatures.", "author_names": [ "T Paul Chow", "Ritu Tyagi" ], "corpus_id": 111115724, "doc_id": "111115724", "n_citations": 421, "n_key_citations": 4, "score": 0, "title": "Wide bandgap compound semiconductors for superior high voltage unipolar power devices", "venue": "", "year": 1994 }, { "abstract": "Gallium oxide (Ga2O3) is a strong contender for power electronic devices. The material possesses excellent properties such as a large bandgap of 4.7 4.9 eV for a high breakdown field of 8 MV cm 1. Low cost, high volume production of large single crystal b Ga2O3 substrates can be realized by melt growth methods commonly adopted in the industry. High quality n type Ga2O3 epitaxial thin films with controllable carrier densities were obtained by ozone molecular beam epitaxy (MBE) We fabricated Ga2O3 metal semiconductor field effect transistors (MESFETs) and Schottky barrier diodes (SBDs) from single crystal Ga2O3 substrates and MBE grown epitaxial wafers. The MESFETs delivered excellent device performance including an off state breakdown voltage (Vbr) of over 250 V, a low leakage current of only few mA mm 1, and a high drain current on/off ratio of about four orders of magnitude. The SBDs also showed good characteristics such as near unity ideality factors and high reverse Vbr. These results indicate that Ga2O3 can potentially meet or even exceed the performance of Si and typical widegap semiconductors such as SiC or GaN for ultrahigh voltage power switching applications.", "author_names": [ "Masataka Higashiwaki", "Kohei Sasaki", "Akito Kuramata", "Takekazu Masui", "Shigenobu Yamakoshi" ], "corpus_id": 118082227, "doc_id": "118082227", "n_citations": 286, "n_key_citations": 5, "score": 0, "title": "Development of gallium oxide power devices", "venue": "", "year": 2014 }, { "abstract": "Lead halide perovskite semiconductors have recently gained wide interest following their successful embodiment in solid state photovoltaic devices with impressive power conversion efficiencies, while offering a relatively simple and low cost processability. Although the primary optoelectronic properties of these materials have already met the requirement for high efficiency optoelectronic technologies, industrial scale up requires more robust processing methods, as well as solvents that are less toxic than the ones that have been commonly used so successfully on the lab scale. Here we report a fast, room temperature synthesis of inks based on CsPbBr3 perovskite nanocrystals using short, low boiling point ligands and environmentally friendly solvents. Requiring no lengthy post synthesis treatments, the inks are directly used to fabricate films of high optoelectronic quality, exhibiting photoluminescence quantum yields higher than 30% and an amplified spontaneous emission threshold as low as 1.5 mJ cm 2. Finally, we demonstrate the fabrication of perovskite nanocrystal based solar cells, with open circuit voltages as high as 1.5 V. Despite their impressive performance, more efforts are required to develop industrially scalable perovskite solar cells from less toxic solvents. Towards that aim, this study presents the use of colloidal nanoparticle inks for room temperature fabrication of CsPbBr3 solar cells.", "author_names": [ "Quinten A Akkerman", "Marina Gandini", "Francesco Di Stasio", "Prachi Rastogi", "Francisco Palazon", "Giovanni Bertoni", "James M Ball", "Mirko Prato", "Annamaria Petrozza", "Liberato Manna" ], "corpus_id": 136250330, "doc_id": "136250330", "n_citations": 331, "n_key_citations": 0, "score": 0, "title": "Strongly emissive perovskite nanocrystal inks for high voltage solar cells", "venue": "", "year": 2017 }, { "abstract": "The high voltage gain converter is widely employed in many industry applications, such as photovoltaic systems, fuel cell systems, electric vehicles, and high intensity discharge lamps. This paper presents a novel single switch high step up nonisolated dc dc converter integrating coupled inductor with extended voltage doubler cell and diode capacitor techniques. The proposed converter achieves extremely large voltage conversion ratio with appropriate duty cycle and reduction of voltage stress on the power devices. Moreover, the energy stored in leakage inductance of coupled inductor is efficiently recycled to the output, and the voltage doubler cell also operates as a regenerative clamping circuit, alleviating the problem of potential resonance between the leakage inductance and the junction capacitor of output diode. These characteristics make it possible to design a compact circuit with high static gain and high efficiency for industry applications. In addition, the unexpected high pulsed input current in the converter with coupled inductor is decreased. The operating principles and the steady state analyses of the proposed converter are discussed in detail. Finally, a prototype circuit is implemented in the laboratory to verify the performance of the proposed converter.", "author_names": [ "Xuefeng Hu", "Chunying Gong" ], "corpus_id": 31740773, "doc_id": "31740773", "n_citations": 242, "n_key_citations": 9, "score": 0, "title": "A High Voltage Gain DC DC Converter Integrating Coupled Inductor and Diode Capacitor Techniques", "venue": "IEEE Transactions on Power Electronics", "year": 2014 }, { "abstract": "Many power switching devices are used in hybrid vehicles (HVs) and electric vehicles (EVs) To improve the efficiency of HVs and EVs, better performance characteristics than those of Si power devices, for example, lower on resistance, higher speed, higher operation temperature, are required for the power devices. GaN power devices are promising candidates for satisfying the requirements. A lateral GaN power device with a blocking voltage of 600 V and a vertical GaN power device with a blocking voltage of 1200 V are suitable for medium power applications for sub systems and high power applications for the drive of main motors, respectively. Power device applications in HVs and EVs and the current status of the GaN power device are presented. The reliability of the GaN power device is also discussed.", "author_names": [ "Tetsu Kachi" ], "corpus_id": 108577842, "doc_id": "108577842", "n_citations": 199, "n_key_citations": 1, "score": 0, "title": "Recent progress of GaN power devices for automotive applications", "venue": "", "year": 2014 }, { "abstract": "The phenomenon of recombination induced stacking faults in high voltage p n diodes in SiC has been previously shown to increase the forward voltage drop due to reduction of minority carrier lifetime. In this paper, it has been shown that, for the first time, this effect is equally important in unipolar devices such as high voltage MOSFETs. If the internal body diode is allowed to be forward biased during the operation of these devices, then the recombination induced SFs will reduce the majority carrier conduction current and increase the leakage current in blocking mode. The effect is more noticeable in high voltage devices where the drift layer is thick and is not expected to impact 600 1200 V devices.", "author_names": [ "Anant K Agarwal", "H Fatima", "Sarah K Haney", "Sei-hyung Ryu" ], "corpus_id": 40295748, "doc_id": "40295748", "n_citations": 163, "n_key_citations": 10, "score": 0, "title": "A New Degradation Mechanism in High Voltage SiC Power MOSFETs", "venue": "IEEE Electron Device Letters", "year": 2007 }, { "abstract": "Superjunction has arguably been the most creative and important concept in the power device field since the introduction of the insulated gate bipolar transistor (IGBT) in the 1980s. It is the only concept known today that has challenged and ultimately proved wrong the well known theoretical study on the limit of silicon in high voltage devices. This paper deals with the history, device and process development, and the future prospects of Superjunction technologies. It covers fundamental physics, technological challenges as well as aspects of design and modeling of unipolar devices, such as CoolMOS. The superjunction concept is compared to other methods of enhancing the conductivity of power devices (from bipolar to employment of wide bandgap materials) to derive its set of benefits and limitations. This paper closes with the application of the superjunction concept to other structures or materials, such as terminations, superjunction IGBTs, or silicon carbide Field Effect Transistors (FETs)", "author_names": [ "Florin Udrea", "Gerald Deboy", "T Fujihira" ], "corpus_id": 7667509, "doc_id": "7667509", "n_citations": 134, "n_key_citations": 7, "score": 0, "title": "Superjunction Power Devices, History, Development, and Future Prospects", "venue": "IEEE Transactions on Electron Devices", "year": 2017 }, { "abstract": "Despite significant development recently, improving the power conversion efficiency of organic photovoltaics (OPVs) is still an ongoing challenge to overcome. One of the prerequisites to achieving this goal is to enable efficient charge separation and small voltage losses at the same time. In this work, a facile synthetic strategy is reported, where optoelectronic properties are delicately tuned by the introduction of electron deficient core based fused structure into non fullerene acceptors. Both devices exhibited a low voltage loss of 0.57 V and high short circuit current density of 22.0 mA cm 2, resulting in high power conversion efficiencies of over 13.4% These unconventional electron deficient core based non fullerene acceptors with near infrared absorption lead to low non radiative recombination losses in the resulting organic photovoltaics, contributing to a certified high power conversion efficiency of 12.6%.Improving the power conversion efficiency is the main target of the organic solar cell research. Here Yuan et al. develop unconventional electron deficient core based non fullerene acceptors to achieve both low voltage loss and high current density, leading to a certified high efficiency of 12.6%", "author_names": [ "Jun Yuan", "Tianyi Huang", "Pei Cheng", "Yingping Zou", "Huotian Zhang", "Jonathan Lee Yang", "Sheng-Yung Chang", "Zhenzhen Zhang", "Wenchao Huang", "Rui Wang", "Dong Meng", "Feng Gao", "Yang Yang" ], "corpus_id": 59603407, "doc_id": "59603407", "n_citations": 181, "n_key_citations": 0, "score": 0, "title": "Enabling low voltage losses and high photocurrent in fullerene free organic photovoltaics", "venue": "Nature Communications", "year": 2019 }, { "abstract": "A generalized optimal pulsewidth modulation (PWM) technique applicable to multilevel inverters for low switching frequency control of medium voltage high power industrial ac drives is presented. Proposed synchronous optimal PWM method allows setting the maximum switching frequency to a low value without compromising the harmonic distortion of machine currents. Low switching frequency reduces the switching losses of the power semiconductor devices, resulting in higher inverter power output and efficiency. The proposed optimization results in low harmonic distortion at low switching frequency. Experimental results of a five level inverter drive using optimal PWM are presented.", "author_names": [ "Akshay Kumar Rathore", "Joachim Holtz", "Till Boller" ], "corpus_id": 25821296, "doc_id": "25821296", "n_citations": 116, "n_key_citations": 6, "score": 0, "title": "Generalized Optimal Pulsewidth Modulation of Multilevel Inverters for Low Switching Frequency Control of Medium Voltage High Power Industrial AC Drives", "venue": "IEEE Transactions on Industrial Electronics", "year": 2013 } ]

[ { "abstract": "This paper researches a method of rating competitiveness involving the estimation of the performance of semiconductor firms through Malmquist productivity index (MPI) and metafrontier Malmquist productivity index (MMPI) Regressions are used to find the relationship between intellectual capital and performance. Overall, technological innovations contribute to the improvement in the integrated circuit (IC) design sub industry while increases in efficient production allow the IC foundry sub industry and the IC packaging and testing sub industry to maintain position. The regression results show human capital was critical to technological innovation while relational capital was important to efficient production.", "author_names": [ "Kuo-Cheng Kuo", "Wen-Min Lu", "Grace Chang" ], "corpus_id": 159398756, "doc_id": "159398756", "n_citations": 2, "n_key_citations": 0, "score": 1, "title": "INTELLECTUAL CAPITAL AND PERFORMANCE IN THE SEMICONDUCTOR INDUSTRY", "venue": "The Singapore Economic Review", "year": 2019 }, { "abstract": "This study utilises the partial least squares method to establish a causal model depicting the relationship between the disclosure of intellectual capital, accounting performance and market valuation with evidence from Taiwan's semiconductor industry. Our results show that accounting performance, mandatory disclosure of intellectual capital performance and voluntary disclosure of intellectual capital have direct effects on market valuation. These factors also indirectly affect market valuation through the cause effect interrelationship with one another. Among the indirect relations, the mandatory disclosure of intellectual capital performance is the most fundamental factor which positively affects accounting performance and voluntary disclosure of intellectual capital and then further affects market valuation. The result provides implications for practice for the financial reporting and management of intellectual capital. In essence, the voluntary disclosure of major intellectual capital and the proper management of leading intellectual capital is valuable to market valuation in Taiwan's semiconductor industry.", "author_names": [ "Wen Ying Wang", "Chingfu Chang" ], "corpus_id": 154747641, "doc_id": "154747641", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "The effect of disclosure of intellectual capital and accounting performance on market valuation: evidence from Taiwan's semiconductor industry", "venue": "", "year": 2008 }, { "abstract": "This study builds an integrated theoretical model to investigate the impact of intellectual capital on business performance and examines the relationships among elements of intellectual capital. The performance measures include both past and expectation oriented performance indicators, i.e. both accounting and market based performance factors. The partial least squares (PLS) approach is applied to examine the Taiwan semiconductor industry. The empirical results show that intellectual capital does affect performance and each intellectual capital element not only directly influences performance, but also indirectly affects performance through the cause and effect relationship between elements. Human capital, the most fundamental element, positively affects both innovation capital and process capital; innovation capital has impact on process capital which, in turn, affects customer capital; and then customer capital ultimately affects business performance. From the perspective of performance management for a semiconductor company, the accumulation and improvement of lagged elements may be facilitated through appropriate management of leading intellectual capital elements. Furthermore, based on the proposed cause and effect model, relevant intellectual capital elements can be identified to effectively enhance business performance.", "author_names": [ "Wen-Ying Wang", "Chingfu Chang" ], "corpus_id": 167604810, "doc_id": "167604810", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "The Impacts of Intellectual Capital on Performance: An Empirical Investigation of the Taiwan Semiconductor Industry", "venue": "", "year": 2004 }, { "abstract": "", "author_names": [ "" ], "corpus_id": 166854059, "doc_id": "166854059", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The Effect of Intellectual Capital and Accounting Performance on Market Valuation: Evidence from Taiwan's Semiconductor Industry", "venue": "", "year": 2006 }, { "abstract": "This study draws on human capital, knowledge based view, and competitive dynamics literature to explore the role of entrepreneurial team's intellectual capital in new ventures ability to apply competitor specific human capital of its members. In particular, we argue that entrepreneurial team's intellectual capital is determined by their potential absorptive capacity, CEO's functional background, and shared team specific experiences of the entrepreneurial team. By utilizing a multi year panel of new IPO firms from the U.S. semiconductor industry between the periods of 1995 2010, the results of this study show that entrepreneurial team's intellectual capital plays a key role in determining their ability to disseminate and apply competitor specific human capital. Moreover, the results show that potential absorptive capacity, CEO's functional background, and shared team specific experiences of the entrepreneurial team moderate the relationship between CSD and CSI human capital and IPO performance.", "author_names": [ "Tapan Seth", "Jaegul Lee", "Amanuel Tekleab" ], "corpus_id": 168498467, "doc_id": "168498467", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Competitor Specific Human Capital IPO Performance: Entrepreneurial Team's Intellectual Capital", "venue": "", "year": 2015 }, { "abstract": "Abstract The commercial semiconductor industry is characterized by fierce competition, large fluctuations in demand, increasing performance, and falling prices. Defense electronics has become a miniscule part of the semiconductor industry (less than 1% but is essential to national security. However, U.S. commercial and defense semiconductor production is losing ground. The industry faces a number of challenges, including: rising capital costs, rapidly evolving technology, future workforce shortages, increasing offshore design and production, infringement of intellectual property rights, and ineffective export controls that hinder U.S. global competitiveness. Furthermore, the defense electronics industry faces significant issues associated with commercial off the shelf components and diminishing manufacturing sources. It is prudent for the U.S. government to recognize the risks of a declining U.S. microelectronics design and production capability, and to plan a course of action to mitigate the emerging risks to national security.", "author_names": [ "Michael E Bonheim", "Gregory Burns", "G Hoffer", "Diana Keys", "Valentyna V Kovalenko", "Alan Maitland", "William C Marks", "Andrew Marotta", "Neal McMahon", "Stanley Specht" ], "corpus_id": 108233818, "doc_id": "108233818", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Electronics Industry Study Report: Semiconductors and Defense Electronics", "venue": "", "year": 2003 }, { "abstract": "In the knowledge economy ear, the value of a firm cannot be evaluated merely by the tangible assets because the company usually creates its value from the intangible assets. This study uses a structural equation model to explore the relationship between the Taiwan semiconductor industry intellectual capitals (including human capital, process capital, innovation capital and customer capital) and enterprise financial performance. The research findings indicate that human capital, process capital, innovation capital and customer capital have a significantly positive correlation with and a direct influential effect on intellectual capitals. Among them, the influence of human capital to corporate performance is the greatest. Moreover, human capital also promotes the growth of innovation and custom capital. Intellectual capital are an important indicator for measuring corporate value in the future. Managers are suggested to control and manipulate intellectual capitals, so as to increase business economic benefit, improve business competitive advantages and create shareholder value.", "author_names": [ "" ], "corpus_id": 211691550, "doc_id": "211691550", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Zhi Hui Zi Ben De Heng Liang Ji Qi Dui Qi Ye Ji Xiao De Ying Xiang Zhi Yan Jiu Yi Tai Wan Shang Shi (Gui )Ban Dao Ti Chan Ye Wei Li", "venue": "", "year": 2009 }, { "abstract": "Performance evaluation is more than a quantitative concept but should also take industrial characteristics into account in order to form an accurate evaluation. In the past, evaluations of the operational performance of knowledge based industries have missed out a significant factor, which is intellectual capital (IC) By adopting data envelopment analysis (DEA) a multiple objective decision making method, this study aims to construct an efficiency evaluation model for the Taiwanese digital content industry based on the perspective of IC. The empirical results suggest that the scale of the digital content companies does play an important role in influencing the operating efficiency. The firms have a small amount of capital can still attain optimal efficiency, from the perspective of IC. In addition, human resource capital and customer capital are the most significant influential factors that deserve digital content firms' attention. It is suggested that enterprises in the digital content industries should focus more on managing their IC. DEA can provide the semiconductor firms' operations with insights into resource allocation and competitive advantage as well as help with strategic decision making.", "author_names": [ "Chia-Chin Chang", "Shiu-Wan Hung", "Sin-Yi Huang" ], "corpus_id": 121787075, "doc_id": "121787075", "n_citations": 16, "n_key_citations": 1, "score": 0, "title": "Evaluating the operational performance of knowledge based industries: the perspective of intellectual capital", "venue": "", "year": 2013 }, { "abstract": "Despite many previous studies, the causal relationship among intellectual property rights (IPR) protection, innovation and economic growth remains ambiguous. Focusing on the differential effects of stronger IPR on industries, we suggest four causal paths from IPR through R&D to economic performance. Using firm level panel data in semiconductor, pharmaceutical and shipbuilding industries in Korea, we find that effective causal paths vary not only by industry but by firm size. Stronger IPR are beneficial to R&D intensive industries where large domestic firms have strong R&D and IPR capabilities, but have no impact on globalized industries. On the other hand, stronger IPR are detrimental to industries and to small and medium enterprises (SMEs) characterized by limited resources. Thus, to boost innovation and economic growth, IPR policies need to be customized to industries as well as SMEs. Universally strong IPR policies are likely to discourage innovation and growth, causing some industries to suffer.", "author_names": [ "Kyung-In Cho", "Changseok Kim", "Juneseuk Shin" ], "corpus_id": 155066829, "doc_id": "155066829", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Differential effects of intellectual property rights on innovation and economic performance: A cross industry investigation", "venue": "", "year": 2015 }, { "abstract": "Given the large investment and prevalence of knowledge management (KM) in organizations, it has become important to analyze the effects of KM activities on organizational performances. A theoretical framework is proposed to investigate the impact of KM activities on innovation capabilities in the IT service industry. This study considers KM activities as the major determinant that enhances absorptive capacity. KM activities enhance employees'ability to obtain external knowledge, resulting in increasing intellectual capital. Thus, this study proposes that absorptive capacity plays a mediating role between KM activities and innovation capability. Additionally, this study investigates the key antecedents of KM activities that promote employees' knowledge sharing. Based on prior studies on KM, this study posits KM team activities and top manager support as KM activities. The proposed research model was tested by using survey data collected from 556 employees in the IT service industry. PLS (partial least squares) was employed for the analysis of the data. The findings of this study showed that KM activities and absorptive capabilities play a significant role in enhancing service innovation and process innovation in the IT service industry. The results also shed light on the mediating role of absorptive capacity between KM activities and innovation capability. Moreover, both KM team activities and top manager support serve as the salient antecedents of promoting employees' knowledge sharing.", "author_names": [ "", "Yong Sauk Hau", "In-Ku Han", "Lee Hee Seok" ], "corpus_id": 167401189, "doc_id": "167401189", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Linking Knowledge Management Activities to Innovation Capability Focused on IT Service Industry", "venue": "", "year": 2010 } ]

[ { "abstract": "A wide range of light absorption and rapid electron hole separation are desired for efficient photocatalysis. Herein, on the basis of a semiconductor like metal organic framework (MOF) a Pt@MOF/Au catalyst with two types of metal MOF interfaces integrates the surface plasmon resonance excitation of Au nanorods with a Pt MOF Schottky junction, which not only extends the light absorption of the MOF from the UV to the visible region but also greatly accelerates charge transfer. The spatial separation of Pt and Au particles by the MOF further steers the formation of charge flow and expedites the charge migration. As a result, the Pt@MOF/Au presents an exceptionally high photocatalytic H2 production rate by water splitting under visible light irradiation, far superior to Pt/MOF/Au, MOF/Au and other counterparts with similar Pt or Au contents, highlighting the important role of each component and the Pt location in the catalyst.", "author_names": [ "Juan-Ding Xiao", "Lili Han", "Jun Luo", "Shuhong Yu", "Hai-Long Jiang" ], "corpus_id": 21096610, "doc_id": "21096610", "n_citations": 212, "n_key_citations": 1, "score": 0, "title": "Integration of Plasmonic Effects and Schottky Junctions into Metal Organic Framework Composites: Steering Charge Flow for Enhanced Visible Light Photocatalysis.", "venue": "Angewandte Chemie", "year": 2018 }, { "abstract": "We report on a high performance Pt/n Ga2O3/n+Ga2O3 solar blind Schottky photodiode that has been grown by metalorganic chemical vapor deposition. The active area of the photodiode was fabricated using ~30 A thick semi transparent Pt that has up to 90% transparency to UV radiation with wavelengths 260 nm. The fabricated photodiode exhibited Schottky characteristics with a turn on voltage of ~1 V and a rectification ratio of ~108 at 2 V and showed deep UV solar blind detection at 0 V. The Schottky photodiode exhibited good device characteristics such as an ideality factor of 1.23 and a breakdown voltage of ~110 V. The spectral response showed a maximum absolute responsivity of 0.16 A/W at 222 nm at zero bias corresponding to an external quantum efficiency of ~87.5% The cutoff wavelength and the out of band rejection ratio of the devices were ~260 nm and ~104, respectively, showing a true solar blind operation with an excellent selectivity. The time response is in the millisecond range and has no long time decay component which is common in photoconductive wide bandgap devices.We report on a high performance Pt/n Ga2O3/n+Ga2O3 solar blind Schottky photodiode that has been grown by metalorganic chemical vapor deposition. The active area of the photodiode was fabricated using ~30 A thick semi transparent Pt that has up to 90% transparency to UV radiation with wavelengths 260 nm. The fabricated photodiode exhibited Schottky characteristics with a turn on voltage of ~1 V and a rectification ratio of ~108 at 2 V and showed deep UV solar blind detection at 0 V. The Schottky photodiode exhibited good device characteristics such as an ideality factor of 1.23 and a breakdown voltage of ~110 V. The spectral response showed a maximum absolute responsivity of 0.16 A/W at 222 nm at zero bias corresponding to an external quantum efficiency of ~87.5% The cutoff wavelength and the out of band rejection ratio of the devices were ~260 nm and ~104, respectively, showing a true solar blind operation with an excellent selectivity. The time response is in the millisecond range and has no long ti.", "author_names": [ "Fikadu Alema", "Brian Hertog", "Partha Mukhopadhyay", "Yuewei Zhang", "Akhil Mauze", "Andrei Osinsky", "Winston V Schoenfeld", "James S Speck", "Timothy J Vogt" ], "corpus_id": 104355239, "doc_id": "104355239", "n_citations": 32, "n_key_citations": 0, "score": 0, "title": "Solar blind Schottky photodiode based on an MOCVD grown homoepitaxial b Ga2O3 thin film", "venue": "APL Materials", "year": 2019 }, { "abstract": "Studies of chemically induced hot electron flow over Schottky barriers in catalytic planar nanostructures provide a direct insight into underlying charge transfer processes involved in chemical energy dissipation at solid surfaces. A systematic approach is described here to separate the hot electron and thermal current contributions to the total generated current based on in situ resistive heating of cathode nanolayer of the Schottky structure. The method is applicable at high pressures in the gas phase. Analysis of the current induced by H2 oxidation to H2O on Pt/n GaP nanostructure is performed for surface temperatures in the range of 453 513 K, and 120 Torr oxyhydrogen environment with 15 Torr H2. All the current components grow monotonously with temperature, while relative fraction of the hot electron current decreases with temperature from 85 to 52%", "author_names": [ "Mohammad A Hashemian", "Suhas Kiran K Dasari", "Eduard G Karpov" ], "corpus_id": 95386182, "doc_id": "95386182", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Separation of hot electron current component induced by hydrogen oxidation on resistively heated Pt/n GaP Schottky nanostructures", "venue": "", "year": 2013 }, { "abstract": "The present invention discloses an electric blasting Schottky junction transducer element, the transducer element electric blasting comprising: a silicon substrate, SiO2 insulating layer, metal aluminum layer, the Schottky junction layer bridge; the present invention with now as compared to prior art, which is a significant advantage in that each of the Schottky junction has a certain breakdown voltage, the excitation energy transducer element controlled by controlling the amount of the Schottky junction; Schottky junction having a reverse breakdown characteristics, so that the transducer element is resistant to stray current, with security nature; of Al and CuO redox reaction to occur, to achieve output energy transducer element is increased.", "author_names": [ "" ], "corpus_id": 139976762, "doc_id": "139976762", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Schottky junction explosive electric transducer component and manufacturing method thereof", "venue": "", "year": 2013 }, { "abstract": "We have proposed a method of surface passivation with high temperature atomic layer deposited (ALD) Al2O3 layer on the fully recessed anode AlGaN/GaN based Schottky barrier diode (SBD) and systematically analyzed the cause of the lateral and the vertical leakage component in the SBD. The forward turn on voltage of the recessed SBD decreased to 0.38 V from the value of 0.8 V of the nonrecessed SBD due to the lowered barrier height. Application of the ALD Al2O3 surface passivation layer to the recessed SBD, which was deposited at higher temperature (550 degC) significantly improved the performances of the proposed SBD such as high on current of 12 A at 1.5 V and increased breakdown voltage of 780 V with greatly decreased reverse leakage current (at least 3 orders lower in magnitude) compared to the corresponding on current of 6 A at 1.5 V and breakdown voltage of 510 V of the reference SBD.", "author_names": [ "Jae-Hoon Lee", "Ki-Sik Im", "Jong Kyu Kim", "Jung-Hee Lee" ], "corpus_id": 56717769, "doc_id": "56717769", "n_citations": 5, "n_key_citations": 0, "score": 1, "title": "Performance of Recessed Anode AlGaN/GaN Schottky Barrier Diode Passivated With High Temperature Atomic Layer Deposited Al2O3 Layer", "venue": "IEEE Transactions on Electron Devices", "year": 2019 }, { "abstract": "We fabricate Schottky contact photodetectors based on electrically contacted Au nanoantennas on p Si for the plasmonic detection of sub bandgap photons in the optical communications wavelength range. Based on a physical model for the internal photoemission of hot carriers, photons coupled onto the Au nanoantennas excite resonant plasmons, which decay into energetic \"hot\" holes emitted over the Schottky barrier at the Au/p Si interface, resulting in a photocurrent. In our device, the active Schottky area consists of Au/p Si contact and is very small, whereas the probing pad for external electrical interconnection is larger but consists of Au/Ti/p Si contact having a comparatively higher Schottky barrier, thus producing negligible photo and dark currents. We describe fabrication that involves an electron beam lithography step overlaid with photolithography. This highly compact component is very promising for applications in high density Si photonics.", "author_names": [ "Mohammad Alavi-Rad", "A Olivieri", "Langis Roy", "Pierre Berini" ], "corpus_id": 59420197, "doc_id": "59420197", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Fabrication of electrically contacted plasmonic Schottky nanoantennas on silicon", "venue": "", "year": 2018 }, { "abstract": "A comprehensive study of the breakdown voltage optimization of trench MOS barrier Schottky (TMBS) rectifiers is performed by means of drift diffusion simulations. First, the principles of operation are explained in terms of the charge sharing effect between the Schottky and trench MOS components of the unit cell, and correlated with the profiles of the electric field along the drift region <inline formula> <tex math notation=\"LaTeX\"{E}_{\\textsf {Sch} /tex math>/inline formula> and the MOS capacitor <inline formula> <tex math notation=\"LaTeX\"{E}_{\\textsf {TMOS} /tex math>/inline formula> Then, the systematic variation of relevant design parameters is used to determine breakdown voltage and leakage current trends, which are analyzed in terms of the electric field. Our results show that <inline formula> <tex math notation=\"LaTeX\"{E}_{\\textsf {Sch} /tex math>/inline formula> is the dominating component in structures with thick oxides, shallow trenches, or high doping concentrations, whereas <inline formula> <tex math notation=\"LaTeX\"{E}_{\\textsf {TMOS} /tex math>/inline formula> is the limiting factor for devices with thin oxides, deep trenches, or low doping. Finally, optimum <inline formula> <tex math notation=\"LaTeX\"\\textit {BV} /tex math>/inline formula> is found when the peak value of <inline formula> <tex math notation=\"LaTeX\"{E}_{\\textsf {Sch} /tex math>/inline formula> and <inline formula> <tex math notation=\"LaTeX\"{E}_{\\textsf {TMOS} /tex math>/inline formula> is approximately the same, and this condition can be reached in a wide range of trench depths for devices with long drift regions and high doping, but in a very narrow window for thin epi layers or low doping concentration.", "author_names": [ "Alvaro D Latorre-Rey", "Mihir Mudholkar", "Mohammed Tanvir Quddus" ], "corpus_id": 3405591, "doc_id": "3405591", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Physics Based Breakdown Voltage Optimization of Trench MOS Barrier Schottky Rectifiers", "venue": "IEEE Transactions on Electron Devices", "year": 2018 }, { "abstract": "Abstract Owing to fascinating optical and electronic properties, graphene has attracted significant attention as an active component in energy harvesting. Steady advances have been achieved in last decade on the hybrid graphene/silicon Schottky solar cells that are based on an unconventional Schottky structured junction. In this brief review, we outlined the device physics and technical strategies devised to improve the power conversion efficiency of the hybrid graphene/silicon Schottky solar cells. The research results accumulated in the graphene/silicon prototype are expected to promote the low cost solar cells.", "author_names": [ "Shihao Ju", "Binxi Liang", "Junzhuan Wang", "Yi Shi", "Songlin Li" ], "corpus_id": 126036255, "doc_id": "126036255", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Graphene/silicon Schottky solar cells: Technical strategies for performance optimization", "venue": "", "year": 2018 }, { "abstract": "In this paper, we investigate the presence of minority carriers and their role in charge carrier transport in silicon (Si) Schottky diodes with a high potential barrier. Using TCAD simulations along with an analytical model, we show that an inversion charge is induced at the metal semiconductor (MS) interface in a high barrier Schottky diode which imparts bipolar type current characteristics to otherwise a unipolar Schottky diode, even at low injection operation. In such a high barrier diode, minority diffusion also becomes important along with the majority carrier thermionic emission and therefore cannot be neglected, unlike in a conventional Schottky diode. The presence of minority carriers at low injection in a high barrier Si Schottky diode has been experimentally verified via a prior reported two diode electrical test method, reverse recovery measurements, and by measuring infrared electroluminescence. It is also shown, via TCAD simulations, that the diffusion component becomes more pronounced in case of a reduced Gummel number and at elevated temperatures.", "author_names": [ "Gaurav Gupta", "Satadal Dutta", "Souri Banerjee", "Raymond J E Hueting" ], "corpus_id": 3986123, "doc_id": "3986123", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Minority Carrier Injection in High Barrier Si Schottky Diodes", "venue": "IEEE Transactions on Electron Devices", "year": 2018 }, { "abstract": "Electrical characteristics of leakage current paths in vertical type n GaN Schottky barrier diodes (SBDs) on free standing GaN substrates are investigated by using photon emission microscopy (PEM) The PEM mapping shows that the initial failure of the SBD devices at low voltages is due to the leakage current paths from polygonal pits in the GaN epilayers. It is observed that these polygonal pits originate from carbon impurity accumulation to the dislocations with a screw type component by microstructure analysis. For the SBD without polygonal pits, no initial failure is observed and the first leakage appeals at the edge of electrodes as a result of electric field concentration. The mechanism of leakage at pits is explained in terms of trap assisted tunneling through fitting current voltage characteristics.", "author_names": [ "Liwen Sang", "B Ren", "Masatomo Sumiya", "Meiyong Liao", "Yasuo Koide", "Atsushi Tanaka", "Yujin Cho", "Y Harada", "Toshihide Nabatame", "Takashi Sekiguchi", "Shigeyoshi Usami", "Yoshio Honda", "Hiroshi Amano" ], "corpus_id": 126347385, "doc_id": "126347385", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "Initial leakage current paths in the vertical type GaN on GaN Schottky barrier diodes", "venue": "", "year": 2017 } ]

[ { "abstract": "The development of fast response, highly accurate methane sensor becoming an important target for their indispensable role in the detection of methane during the coal mine and natural gas transportation, supply and use. In this cut edge review, we summarized the development of gas sensors in these years in both technology and materials aspects. We believe this review could inspire scientists, inventors, researchers and engineers in this field. The methane sensors can be divided into semiconductor resistive type gas sensors, optical fiber gas sensors and mass sensitive gas sensors according to their functions. For example, the typical methane gas sensing materials can be divided into semiconductor metal oxides, nanocomposites, organic polymer composites, cryptophane A, carbon nanotubes and their doping materials etc. Semiconductor metal oxide nanomaterials such as SnO2, ZnO, In2O3, Fe2O3, Co3O4 are the most used methane gas sensing materials. In a certain temperature range, the resistance of the gas sensor can be changed by the adsorption and desorption of methane molecules with the surface of semiconductor metal oxide film. In order to promote the sensitivity and lower the working temperature of methane sensors with semiconductor metal oxides, noble metal nanoparticles, carbon nanotubes or graphene were doped into metal oxides to form nanocomposites. The methane sensor prepared by doped polymer composites could work at room temperature which made it more applicable in closed, flammable and explosive places. Cryptophane A has an amazing affinity for methane. When cryptophane A was exposed to the methane gas, the methane molecules would enter the cavity of the cryptophane A. Furthermore, some studies have shown that CNTs doped with noble metals were sensitive to methane but remain controversial. The future challenges and opportunities in this field are also discussed in the perspective section. The exploitation of high response, high sensitivity and selectivity methane sensing materials which can work at room temperature remains a major challenge. The properties of methane sensors can be improved from grain size, porosity and thickness of gas sensing materials. With the development of preparation process of gas sensing materials and intelligent control technology, the intelligent gas sensors which could monitor many kinds of gas would be one trend in development of methane gas sensor.", "author_names": [ "Yanbao Guo", "Chengcheng Liu", "Deguo Wang", "Renyang He" ], "corpus_id": 181522729, "doc_id": "181522729", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Advances in the development of methane sensors with gas sensing materials", "venue": "Chinese Science Bulletin", "year": 2019 }, { "abstract": "Methane is an explosive gas in coalmines and needs to be monitored by methane sensors. Conductive type methane sensors are small, simple and stable, and they are very promising for mining safety or home safety applications. They can even be employed in mining Internet of things if the power consumption can be lowered down to few milliwatts. Many researches of nanomaterials based conductive type methane sensors have been reported recently. This review intends to present a comprehensive and critical summary on the recent progresses in the nanomaterials based conductive type methane sensors field. Many excellent methane sensitive nanomaterials will be present, such as SnO2, ZnO, TiO2, WO3, carbon nanotubes, graphene, rare earth metal based perovskite oxides and their hybrids. Particular attention is given to the synthetic methods of the nanomaterials, sensing mechanisms of the nanomaterials and the relationship between the sensing performance and the structures and components of the nanomaterials. Finally, the future trends and perspectives of nanomaterials based conductive type methane sensors are proposed.", "author_names": [ "Ming-Zhi Jiao", "Xiao-Yu Chen", "Ke-xiang Hu", "De-Yu Qian", "Xiao-Hu Zhao", "En-Jie Ding" ], "corpus_id": 232044359, "doc_id": "232044359", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Recent developments of nanomaterials based conductive type methane sensors", "venue": "Rare Metals", "year": 2021 }, { "abstract": "Methane (CH4) gas sensors play an important role in industrial safety and detection of indoor gas quality. In general, metal oxide semiconductor sensing materials with nano structure have high responses to the target gas. However, the sensor resistance is usually very high. Considering the practical application, it is vital to reduce base resistance and improve sensitivity for gas sensors. Herein, Pd doped SnO2 nanoparticles were prepared as the basis material by a simple sol gel method. In order to adjust the resistance, the pentavalent metal element (Sb) was introduced via a simple doping route. As CH4 sensing layers, the prepared SnO2 sensors doped with Pd and Sb exhibited the most obvious resistance reduction effect. Meantime, excellent sensing performances including high response, fast response/recovery time, excellent reproducibility and great stability were also obtained. In depth research has shown that the ability to reduce resistance depends on the effective internal doping of cation with high valence. The enhanced sensing capability can be attributed to the 'synergistic effects' including catalytic effects of novel metals, increased oxygen vacancies and decreased band gap energy. This work can provide a new opportunity to design metal oxide sensing materials with low resistance and high sensitivity.", "author_names": [ "Jiawen Shi", "Sen Liu", "Ning Sui", "Shuang Cao", "Tingting Zhou", "Tong Zhang" ], "corpus_id": 233985754, "doc_id": "233985754", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Sb/Pd co doped SnO2 nanoparticles for methane detection: resistance reduction and sensing performance studies", "venue": "Nanotechnology", "year": 2021 }, { "abstract": "Two projects were designed and implemented in an effort to gather high quality data focused on two metrics important to environmental science: methane emissions from cities and the flow rate of sap in trees. Methane is a powerful greenhouse gas that is emitted to the atmosphere in many ways. In cities, these sources include landfills and fugitive emissions from natural gas infrastructure, and the quantification of these emissions is an important area of research. Sap flow, which is a direct measure of the water use of a tree, is also vital to the understanding of rates of carbon exchange between the atmosphere and the biosphere. A recently developed technology, the EM27/SUN spectrometer, was deployed in the city of Indianapolis for a five day measurement campaign. Five of the sensors were spread across the greater urban area so that atmospheric methane concentrations could be measured as air moved across the city. An inverse modelling framework was designed which combined these observations with a trace gas transport model and information on the location and predicted magnitude of methane sources. This framework was able to estimate the magnitude of emissions from small diffuse sources, such as individual pipeline leaks, spread across the urban domain. Diffuse emissions from the city were found to be 47.0 14.8Gg yr 1, which was more twice the suggested by some bottom up inventories, but consistent with other observation and modelling efforts. The insights gained during this project are important to future urban measurement and modelling efforts, especially those using remote sensing sensors like the EM27/SUN or current and future satellites. The second project was the development of new sensor to measure the flow rate of sap in trees. There are two issues with conventional sap flow sensors which limit their widespread use. The first is that the probes are costly and difficult to manufacture. The second major issue is that installing the probes correctly, so that they are aligned properly with each other, is quite difficult which introduces large uncertainties in the data. The new design, the ribbonized sap flow (RSF) sensor solves these issues by placing all of the components of the sensor onto a single circuit board that can be easily slid into a slot made in the tree, and can be manufactured at much lower cost. This sensor, and a custom control and data collection system, were designed, built, calibrated, and tested in field conditions in multiple locations. The results from the calibration suggest that the RSF system has the sensitivity and accuracy needed to make meaningful sap flow measurements, and the reduced cost over conventional systems make in an appealing option for future sap flow deployments.", "author_names": [ "Taylor S Jones" ], "corpus_id": 214316232, "doc_id": "214316232", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Advances in Environmental Measurement Systems: Remote Sensing of Urban Methane Emissions and Tree Sap Flow Quantification", "venue": "", "year": 2019 }, { "abstract": "Abstract Two dimensional (2D) nanomaterials with porous structure have stimulated much research interest owing to their unique structure and fascinating physical and chemical properties. Here, ultrathin 2D porous nanosheets (PNSs) of pure and SnO2 decorated NiO with uniform hexagonal shape were synthesized by using the pre synthesized Ni(OH)2 nanosheets precursor. The obtained SnO2/NiO PNSs were about 100~150 nm in size and their mean thickness was about 7.5 nm. The gas sensing properties of the prepared pure and SnO2 decorated NiO PNSs were investigated intensively. It was found that after decorating with different amount of SnO2, the sensor based on NiO PNSs showed an improved sensing properties to methane (CH4) and the optimal SnO2 content in the composite was determined to be 2 mol% At the optimum working temperature of 330 degC, the SnO2/NiO 2 sensor showed higher response and faster response/recover speed towards 500 ppm CH4 than the pure NiO sensor. In addition, the SnO2/NiO 2 sensor also exhibited a good long term stability within 28 days, demonstrating its potential application for CH4 detection. The porous structure and p n junction related sensing mechanism of SnO2/NiO PNSs was also discussed.", "author_names": [ "Saisai Zhang", "Yanwei Li", "Guang Sun", "Bo Zhang", "Yan Wang", "Jianliang Cao", "Zhanying Zhang" ], "corpus_id": 108073274, "doc_id": "108073274", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Enhanced methane sensing properties of porous NiO nanaosheets by decorating with SnO2", "venue": "Sensors and Actuators B: Chemical", "year": 2019 }, { "abstract": "Abstract In this research, flame spray made 0 2 wt% Cr doped SnO2 nanoparticles were synthesized and methodically studied for specific detection of methane (CH4) for the first time. From characterizations using X ray diffraction, X ray photoelectron spectroscopy, scanning/transmission electron microscopy and nitrogen adsorption, Cr was found to form substitutional solid solution in 5 20 nm nanoparticles with tetragonal SnO2 structure. In addition, grain and particle sizes decreased while surface area increases considerably with increasing Cr content. The sensing films prepared by spin coating technique were evaluated towards various flammable and toxic gases in dry air at 200 400 degC. Gas sensing data evidently showed that the SnO2layer with the optimum Cr doping level of 0.5 wt% offered a remarkable response of ~1268 with a decent response time of ~3.9 s to 1 vol% CH4at the optimum working temperature of 350 degC. In addition, the optimal Cr doped SnO2sensor gave high CH4 selectivity against H2, C2H2, NO2, NO, N2O, CO, NH3, SO2, C2H5OH, C3H6O and H2O. Therefore, the flame spray made Cr doped SnO2material is an attractive choice for selective and sensitive detection of CH4.", "author_names": [ "K Bunpang", "Anurat Wisitsoraat", "Adisorn Tuantranont", "Suparat Singkammo", "Sukon Phanichphant", "Chaikarn Liewhiran" ], "corpus_id": 145983539, "doc_id": "145983539", "n_citations": 29, "n_key_citations": 2, "score": 0, "title": "Highly selective and sensitive CH4 gas sensors based on flame spray made Cr doped SnO2 particulate films", "venue": "Sensors and Actuators B: Chemical", "year": 2019 }, { "abstract": "Nowadays, gas sensors are fast becoming an imperative part of modern life with extensive applications in domestic safety, environmental monitoring, industrial process control, public security, medical applications and chemical warfare assessment amongst many others. The detection of minor gas leaks has been a challenging area of research, particularly in view of the hazards to human health and safety posed by toxic gases like NO2, NO, CO, NH3 etc and combustible gases like methane, hydrogen gas and some volatile organic compounds. Thus it is imperative to evolve and employ simple yet reliable gas sensing mechanisms with optimum response and selectivity towards even low concentration of analyte gas at room temperature. Most of the conventional gas sensors are based on metal oxide semiconductors which are low cost, exhibit good sensitivity and fast response/recovery. Zinc oxide is one such n type semiconducting oxide, which has been widely studied for gas sensing response due to its ease of fabrication, high sensitivity and environment friendly nature. However, the operating temperature of such sensors is usually high >200degC) owing to the wide band gap (3.37 eV) and high electrical resistance (kO MO) which limits their practical utilization. In order to be used in hazard monitoring and home/workplace safety, the gas sensors need to be sensitive to gas exposure in mild operating conditions. As an alternative, more recently, graphene and its derivatives like pristine graphene (PG) reduced graphene oxide (rGO) etc. have been studied for sensing applications owing to their exceptional electronic and physical properties such as high carrier mobility at room temperature, good thermal stability, high mechanical strength, ballistic conductivity and large specific surface area. These sensors show high sensitivity at low operating temperatures (down to room temperature) towards low concentrations of analyte gas. However most of these rGO based sensors exhibit relatively longer response/recovery times than metal oxide based gas sensors. Hence, nanocomposites formed by hybridizing graphene or its derivatives with metal oxide nanoparticles are being explored as gas sensing materials. Combining reduced graphene oxide with zinc oxide to form hybrid nanostructures is particularly interesting because not only do they display the individual properties of the metal oxide NPs (faster response/recovery times) and of graphene (high electronic conductivity leading to efficient room temperature gas response) but may also have synergistic effects leading to better sensitivity as a gas sensing material. Here we present a review of the recent progress in rGO ZnO nanocomposites based gas sensors. Copyright (c) 2018 VBRI Press.", "author_names": [ "Sitakshi Gupta", "Chhaya Ravikant" ], "corpus_id": 139851138, "doc_id": "139851138", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Reduced graphene oxide zinc oxide nano composites for gas sensing applications", "venue": "", "year": 2018 }, { "abstract": "In the late summer of 2016, our team deployed a network of low cost air quality sensing systems in partnership with community based organizations in a neighborhood in South Los Angeles, California. Residents of this community were concerned about possible emissions from local oil and gas activity, however in addition to these potential emissions, the neighborhood is also subject to a complex mixture of pollutants from other nearby sources including major highways. For this deployment, metal oxide VOC sensors were quantified to provide methane (CH4) and total non methane hydrocarbon (TNMHCs) concentration estimates. This data along with other sensor signals, meteorological data, and community member observations was used to examine the composition and possible origins of observed emissions. The sensor network displayed expected environmental trends and highlighted short term elevations in CH4 and/or TNMHCs, which we were then able to investigate more closely. The results indicated that sources of both combusted and volatilized hydrocarbons were likely affecting air quality throughout the community, including near the site of the local oil and gas activity. This deployment may serve as a model for how multi sensor systems deployed in networks can be leveraged to better understand sources in complex areas, potentially supporting future community based air quality research.", "author_names": [ "Ashley Collier-Oxandale", "Nicole J Wong", "Sandy Navarro", "Jill E Johnston", "Michael Hannigan" ], "corpus_id": 218927897, "doc_id": "218927897", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Using Gas Phase Air Quality Sensors to Disentangle Potential Sources in a Los Angeles Neighborhood.", "venue": "Atmospheric environment", "year": 2020 }, { "abstract": "Abstract A compact refractive index (RI) sensor, based on the Mach Zehnder Interferometer (MZI) has been developed and experimentally evaluated for the highly sensitive detection and quantification of gases (Helium, Methane, and Carbon Dioxide) The RI sensor utilizes a variety of fibre types: Single Mode Fibre (SMF) Photonic Crystal Fibre (PCF) and Hollow Core Photonic Crystal Fibre (HC PCF) In order to fabricate the MZI sensors, a short length of sensing fibre was positioned between a lead in and a lead out single mode fibre (SMF) with an air gap at each interface. Three types of sensors were fabricated using this configuration employing 4 mm stub of: (i) PCF, (ii) 10 um HC PCF, and (iii) 20 um HC PCF as the sensing elements. The performance of these sensors, for detecting and measuring the quantity of gas present, were compared. The transmission spectrum of MZI sensors are formed by interference between the cladding and core modes. These transmission signals correspond to the frequency components in the sensor's Fast Fourier Transform (FFT) spectrum. The effect of gap distance on the number and amplitude distribution of the modes was examined in an effort to optimize the design elements. The resulting fiber sensors can measure the RI of a gas filled cavity and they showed high sensitivity to helium, methane, and carbon dioxide. The highest RI sensitivity of 3210 nm/RIU was demonstrated in the RI range of 1.0000347 to 1.000449 by a sensor with a 4 mm long sensing stub element of 10 um HC PCF. Cyclic tests with the group of gases demonstrated that the measurements are highly repeatable. The measurement response and recovery times for all sensors were determined, and it was concluded that the 20 um HC PCF sensor has the fastest response/recovery time and the PCF sensor has the slowest. This research illustrates that the sensors fabricated by the proposed method have potential for improving the ability to detect and quantify pure gases. Additionally, the sensors are highly sensitive to low percentages of CO2, making them suitable for greenhouse gas measurement.", "author_names": [ "Kaveh Nazeri", "Colin Bradley" ], "corpus_id": 225329705, "doc_id": "225329705", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The effect of photonic crystal fibre structure on the performance of Mach Zehnder interferometer fibre optic gas sensors", "venue": "", "year": 2020 }, { "abstract": "Reducing the operating temperature to room temperature is a serious obstacle on long life sensitivity with long term stability performances of gas sensors based on semiconducting oxides and this should be overcome by new nano technological approaches. In this work, we report the structural, morphological, chemical, optical and gas detection characteristics of Eu doped ZnO (ZnO:Eu) columnar films as a function of Eu content. The scanning electron microscopy (SEM) investigations showed that columnar films, grown via synthesis from chemical solutions (SCS) approach, are composed of densely packed columnar type grains. The sample sets with a content of ~0.05, 0.1, 0.15 and 0.2 at% of Eu in ZnO:Eu columnar films were studied. The surface functionalization was achieved using PdCl2 aqueous solution with additional thermal annealing in air at 650 oC. The temperature dependent gas detection characteristics of Pd functionalized ZnO:Eu columnar films were measured in detail, showing a good selectivity towards H2 gas at operating OPT temperatures of 200 300 oC among several test gases and volatile organic compounds (VOCs) vapors; such as methane, ammonia, acetone, ethanol, n butanol and 2 propanol. At an operating temperature OPT of 250 oC a high gas response Igas/Iair 115 for 100 ppm H2 was obtained. Experimental results indicate that Eu doping with an optimal content about 0.05 0.1 at% along with Pd functionalization of ZnO columns leads to a reduction of the operating temperature of the H2 gas sensor. DFT based computations provide mechanistic insights into the gas sensing mechanism by investigating interactions between the Pd functionalized ZnO:Eu surface and H2 gas molecules supporting the experimentally observed results. The proposed columnar materials and gas sensor structures would provide a special advantage in the fields of fundamental research, applied physics studies, ecological and industrial applications.", "author_names": [ "Cristian Lupan", "Rasoul Khaledialidusti", "Abhishek Kumar Mishra", "Vasile Postica", "Maik-Ivo Terasa", "Nicolae A Magariu", "Thierry Pauporte", "Bruno Viana", "Jonas Drewes", "Alexander Vahl", "Franz Faupel", "Rainer Adelung" ], "corpus_id": 218505966, "doc_id": "218505966", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Pd Functionalized ZnO:Eu Columnar Films for Room Temperature Hydrogen Gas Sensing: A Combined Experimental and Computational Approach.", "venue": "ACS applied materials interfaces", "year": 2020 } ]

[ { "abstract": "Continued scaling of semiconductor devices in logic and memory applications requires the introduction of high k (HK) dielectrics to enhance the capacitance density while maintaining a low leakage. Of particular concern in DRAM memory applications is the so called `dielectric relaxation current' which is significantly enhanced with HfO2 dielectrics as compared to SiO2. In this paper, it is shown that these relaxation currents arise from electron trapping/detrapping by/from oxygen vacancy defects in the HfO2 dielectric from/to the contact electrodes. This understanding is utilized to minimize `dielectric relaxation currents' by optimizing the defect structure in the HK dielectric. By creating trap free dielectric films with N or La doping, we show that substantial reductions in the relaxation currents can be achieved. For the first time, it is demonstrated that a HK dielectric stack formed as a result of these treatments can have reduced relaxation currents similar to SiO2, thus providing a pathway to solving a fundamental paradigm associated with HK dielectrics that has persisted for several years.", "author_names": [ "Eduard Cartier", "Takashi Ando", "Marco J P Hopstaken", "Vijay Narayanan", "Rishikesh Krishnan", "Joseph F Shepard", "M D Sullivan", "Siddarth A Krishnan", "Michael P Chudzik", "Sandip De", "Rajan Kumar Pandey", "Mohit Bajaj", "Kota Murali", "Andreas Kerber" ], "corpus_id": 37198151, "doc_id": "37198151", "n_citations": 7, "n_key_citations": 0, "score": 1, "title": "Characterization and optimization of charge trapping in high k dielectrics", "venue": "2013 IEEE International Reliability Physics Symposium (IRPS)", "year": 2013 }, { "abstract": "We compare the intrinsic reliability of the dielectric stack of a high performance bulk planar 20nm replacement gate technology to the reliability of high performance bulk planar 28 nm gate first high k metal gate (HKMG) technology, developed within the IBM Alliance. Comparable N/PFET TDDB and comparable/improved NFET PBTI are shown to be achievable for similar Tinv. The choice to not include channel silicon germanium as a PFET performance element in the 20nm technology impact NBTI, driving a potential tradeoff between NBTI and PBTI. The complexity of integrating such performance elements while accounting for reliability/performance tradeoffs demands their selection during technology definition with due consideration to realistic product usage conditions.", "author_names": [ "William McMahon", "C E Tian", "Suresh Uppal", "H Kothari", "M Jin", "Giuseppe Larosa", "Tanya Nigam", "Andreas Kerber", "Barry P Linder", "Eduard Cartier", "Wing L Lai", "Yang Liu", "Ravikumar Ramachandran", "Unoh Kwon", "Biju Parameshwaran", "Siddarth A Krishnan", "Vijay Narayanan" ], "corpus_id": 6097824, "doc_id": "6097824", "n_citations": 15, "n_key_citations": 1, "score": 0, "title": "Intrinsic dielectric stack reliability of a high performance bulk planar 20nm replacement gate high k metal gate technology and comparison to 28nm gate first high k metal gate process", "venue": "2013 IEEE International Reliability Physics Symposium (IRPS)", "year": 2013 }, { "abstract": "Bias Temperature Instability (BTI) degradation and recovery with different types of MOL capping layers are investigated in a 20nm Replacement Metal Gate (RMG) CMOS technology. It is found that less compressive RMG capping layers substantially improve reliability and device performance because of less hydrogen within the RMG capping material. The hydrogen content plays an important role in BTI degradation and recovery. Increased hydrogen enhances interface state generation during NBTI stress and suppresses h+ trap activation. This change in interface states has minimal impact on PBTI.", "author_names": [ "M Jin", "C E Tian", "Giuseppe La Rosa", "Suresh Uppal", "William McMahon", "H Kothari", "Yang Liu", "Eduard Cartier", "Wing L Lai", "A Dasgupta", "S M Polvino", "Michael P Belyansky", "A Chen", "X Zhou", "A Madan", "Y Yao", "N Klymko", "Vijay Narayanan" ], "corpus_id": 19354347, "doc_id": "19354347", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Impact of hydrogen in capping layers on BTI degradation and recovery in high k replacement metal gate transistors", "venue": "2013 IEEE International Reliability Physics Symposium (IRPS)", "year": 2013 }, { "abstract": "Presents 27 abstracts for the tutorials at IRPS 2013. The complete presentations were not made available for publication as part of the conference proceedings.", "author_names": [ "Robert J Kaplar" ], "corpus_id": 109385658, "doc_id": "109385658", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "2013 IRPS tutorial program [27 abstracts of IRPS tutorials]", "venue": "IRPS 2013", "year": 2013 }, { "abstract": "", "author_names": [ "Gad S Haase" ], "corpus_id": 114309161, "doc_id": "114309161", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "IRPS 2013 tutorial: Reliability of Low k Interconnect Dielectrics in Advanced CMOS Technologies.", "venue": "", "year": 2013 }, { "abstract": "La prochaine seance du seminaire aura lieu le 17 mai de 16h a 18h, a l'Universite Paris I Pantheon Sorbonne, en salle Picard (esc. C, 3e etage) Nous accueillerons Marie Cartier et Christelle Avril, deux sociologues qui presenteront leurs travaux autour des emplois de service a domicile (femmes de menage, aides a domicile pour personnes agees et assistantes maternelles) tres majoritairement exerces par des femmes des classes populaires. Cette seance sera l'occasion d 'aborder la maison comme", "author_names": [ "Anais Albert" ], "corpus_id": 193354485, "doc_id": "193354485", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Prochaine seance du seminaire le 17 mai 2013 la maison comme lieu de travail, avec Marie Cartier et Christelle Avril bibliographie indicative", "venue": "", "year": 2013 }, { "abstract": "Du 19 novembre 2013 au 6 avril 2014, la Fondation Cartier pour l'art contemporain proposa une exposition intitulee America Latina. Photographies 1960 2013, concue en collaboration avec le musee Amparo de Puebla (Mexique) et a la realisation de laquelle l'Institut des hautes etudes de l'Amerique latine a ete associe. Rassemblant les oeuvres de plus de 70 artistes originaires de onze pays differents, cet evenement ambitieux offre au public parisien la possibilite de decouvrir le foisonnement et", "author_names": [ "Olivier Compagnon" ], "corpus_id": 190605044, "doc_id": "190605044", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Un demi siecle de photographie latino americaine a la Fondation Cartier pour l'art contemporain", "venue": "", "year": 2013 }, { "abstract": "Voici quelques photos de notre sortie de fin d'annee cosmodome, biodome, metro (petit extra) et Place Jacques Cartier. Bonnes vacances", "author_names": [ "Melissa Fortin" ], "corpus_id": 227537508, "doc_id": "227537508", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Sortie a Montreal 12 juin 2013 (maternelle et 1re annee)", "venue": "", "year": 2013 }, { "abstract": "Appel a contributions Colloque \"Populations pionnieres, populations coloniales, populations metisses (XVIe XXe siecles)\" Lyon, 25 26 novembre 2013 Centre Jacques Cartier. Date de soumission 15 mars 2013. Les populations des differents continents, et plus particulierement celles des continents africain et americain, telles que nous les connaissons aujourd'hui, sont le fruit de processus historiques complexes. A partir du XVIe siecle, les puissances europeennes sont parties a la conquete d'", "author_names": [ "" ], "corpus_id": 134258873, "doc_id": "134258873", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Appel a contributions. Colloque \"Populations pionnieres, populations coloniales, populations metisses (XVIe XXe siecles)\"", "venue": "", "year": 2013 }, { "abstract": "Le mardi 26 novembre 2013, Lyon BD Festival organise un colloque dedie aux \"Festivals de bande dessinee. Manifestations artistiques, culturelles, sociales et economiques\" dans le cadre des entretiens Jacques Cartier (de 9h00 a 18h00, Hotel de Ville de Lyon) \"Notre objectif dans ce colloque est de voir comment, au dela de l'aspect festif d'un festival de bande dessinee, sont liberees des energies creatrices au service du developpement culturel et economique de notre societe.\" Programme", "author_names": [ "Benedicte Tratnjek" ], "corpus_id": 192575752, "doc_id": "192575752", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Colloque \"Les festivals de bande dessinee\"", "venue": "", "year": 2013 } ]

[ { "abstract": "Properties of Silicon Carbide Junction Field Effect Transistor (SiC JFET) such as high switching speed, low forward voltage drop and high temperature operation have attracted the interest of power electronic researchers and technologists, who for many years developed devices based on Silicon (Si) A number of power system Engineers have made efforts to develop more robust equipment including circuits or modules with higher power density. However, it was realized that several available power semiconductor devices were approaching theoretical limits offered by Si material with respect to capability to block high voltage, provide low on state voltage drop and switch at high frequencies. This paper presents an overview of the current applications of SiC JFET in circuits such as inverters, rectifiers and amplifiers. Other areas of application reviewed include; usage of the SiC JFET in pulse signal circuits and boost converters. Efforts directed toward mitigating the observed increase in electromagnetic interference were also discussed. It also presented some areas for further research, such as having more applications of SiC JFET in harsh, high temperature environment. More work is needed with regards to SiC JFET drivers so as to ensure stable and reliable operation, and reduction in the prices of SiC JFETs through mass production by industries.", "author_names": [ "Frederick Ojiemhende Ehiagwina", "Olufemi Oluseye Kehinde", "Lateef Olashile Afolabi", "Hassan Jimoh Onawola", "Nurudeen Ajibola Iromini" ], "corpus_id": 55404658, "doc_id": "55404658", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Applications, Prospects and Challenges of Silicon Carbide Junction Field Effect Transistor (SIC JFET)", "venue": "", "year": 2016 }, { "abstract": "Throughout the world there have been alarming concerns over the use of non renewable resources during manufacturing of goods and associated environmental legislations. Therefore, the use of natural materials and fabrication of composites there from, particularly, development of natural fibre reinforced polymer composites is gaining significant attention. Although natural fibre reinforced composites (NFRCs) show strong application prospects, various materials and processing related challenges needs to be addressed to achieve long term stability and performance. The volume and number of applications of composite materials have grown steadily, penetrating and conquering new markets relentlessly. So everybody is concentrating on new materials which will be strong enough, less weight, recyclable with reduced cost. Hence all the researchers are concentrated on the composite materials which have all the above properties. The present work is concentrated on corn cob and Rice husk reinforced polymer hybrid composites. The composites specimen was fabricated with various weight percentages of corn cob fibres (25%,20% 15% Rice husk (20% and Silicon carbide(15% combined with lapox 12 resin using hand lay up method. So to obtain new composite materials different proportions of corn cob is added and the mechanical properties such as Tensile strength, Flexural Strength and Impact test were carried out for the samples cut from the fabricated composites specimen to the dimensions as per ASTM standard. With the increasing percentage of the reinforcements the performance of the material is improving. The tensile strength increases with the increase in corncob reinforcement percentage and flexural strength increases with the increasing in percentage of the rice husk and the impact strength of the material gets boost with equal proportional percentage of corncob and rice husk reinforcement.", "author_names": [ "C K Yogish", "S Pradeep", "R Raghavendra Rao", "G Sunil Kumar" ], "corpus_id": 218797598, "doc_id": "218797598", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Effect of silicon carbide on the mechanical properties of the rice husk, corn cob polymer matrix composites", "venue": "", "year": 2020 }, { "abstract": "Abstract One dimensional silicon carbide (1D SiC) nanomaterials have shown unusual properties such as extreme high strength, good flexibility, fracture toughness and inverse Hall petch effect leading to the wide range of applications. However, the fabrication of desired 1D SiC nanomaterials with tailored atomic structures and their assembly into functional devices are still major challenges. In the present review, the recent research and trends towards the formation of SiC nanowires via different routes, their characterization and growth mechanism are discussed. Various aspects of synthesis methods for the bulk production of one dimensional SiC nanomaterials have been discussed with respect to quantity and quality. It is observed that SiC 1D nanostructures grown by different strategies exhibit unusual growth phenomena and properties. The promising myriad applications of 1D SiC nanostructures are highlighted, particularly with reference to surface dependent electronic transduction (gas and biological sensors, potentially useful in biology and medicine as well, for example, in bio labeling) energy conversion devices (nanomechanical and photovoltaic) microelectronic, nanowire photonics and nanocomposites devices. The important aspects of SiC nanomaterials including various fabrication strategies, knowledge of microstructural evolution, applications and toxicity issues are also covered in the present review. It summarizes and projects the future prospects of 1D SiC nanostructures.", "author_names": [ "Jyoti Prakash", "Ramani Venugopalan", "B M Tripathi", "Sunil Kumar Ghosh", "J K Chakravartty", "Avesh K Tyagi" ], "corpus_id": 101881098, "doc_id": "101881098", "n_citations": 43, "n_key_citations": 0, "score": 0, "title": "Chemistry of one dimensional silicon carbide materials: Principle, production, application and future prospects", "venue": "", "year": 2015 }, { "abstract": "Recently, high temperature power devices have become a popular discussion topic because of their various potential applications in the automotive, down hole oil and gas industries for well logging, aircraft, space exploration, nuclear environments, and radars. Devices for these applications are fabricated on silicon carbide based semiconductor material. For these devices to perform effectively, an appropriate die attach material with specific requirements must be selected and employed correctly. This article presents a review of this topic, with a focus on the die attach materials operating at temperatures higher than 623 K (350 degC) Future challenges and prospects related to high temperature die attach materials also are proposed at the end of this article.", "author_names": [ "Hui Shun Chin", "Kuan Yew Cheong", "Ahmad Badri Ismail" ], "corpus_id": 137699697, "doc_id": "137699697", "n_citations": 224, "n_key_citations": 2, "score": 0, "title": "A Review on Die Attach Materials for SiC Based High Temperature Power Devices", "venue": "", "year": 2010 }, { "abstract": "Abstract: Ceramic matrix composites are key materials for advanced energy systems. Silicon carbide (SiC) continuous fibre reinforced SiC matrix composites have promise for fission energy and fusion energy due to their high temperature strength, chemical inertness, irradiation tolerance and the favourable nuclear properties of SiC, and the damage tolerance and predictable strength of the composite structure. SiC based composites can be used to enhance the accident tolerance of light water reactors. These applications require materials with high reliability in harsh conditions, imposing challenges for materials. This chapter reviews the effect of irradiation on SiC and carbon fibre composites, gives an overview of the potential applications of these materials in fusion energy systems and nuclear reactors, and concludes with future prospects and opportunities for research.", "author_names": [ "Yutai Katoh" ], "corpus_id": 137400133, "doc_id": "137400133", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Ceramic matrix composites in fission and fusion energy applications", "venue": "", "year": 2014 }, { "abstract": "Superjunction has arguably been the most creative and important concept in the power device field since the introduction of the insulated gate bipolar transistor (IGBT) in the 1980s. It is the only concept known today that has challenged and ultimately proved wrong the well known theoretical study on the limit of silicon in high voltage devices. This paper deals with the history, device and process development, and the future prospects of Superjunction technologies. It covers fundamental physics, technological challenges as well as aspects of design and modeling of unipolar devices, such as CoolMOS. The superjunction concept is compared to other methods of enhancing the conductivity of power devices (from bipolar to employment of wide bandgap materials) to derive its set of benefits and limitations. This paper closes with the application of the superjunction concept to other structures or materials, such as terminations, superjunction IGBTs, or silicon carbide Field Effect Transistors (FETs)", "author_names": [ "Florin Udrea", "Gerald Deboy", "T Fujihira" ], "corpus_id": 7667509, "doc_id": "7667509", "n_citations": 134, "n_key_citations": 7, "score": 0, "title": "Superjunction Power Devices, History, Development, and Future Prospects", "venue": "IEEE Transactions on Electron Devices", "year": 2017 }, { "abstract": "The third generation of wide bandgap semiconductor as silicon carbide(SiC) breakthroughs the performance caps of silicon(Si) based power semiconductor devices in voltage, temperature, switching loss and switching speed, thus, the weight, size and cost of power electronic converters may be decreased, and the performance of power electronic system may be improved significantly. Power driver of electric vehicles with high power density is always the main development challenge of high power electric vehicles. The usage of wide bandgap semiconductors may has significant impacts on new generation electric vehicles, especially hybrid electric vehicles. In this paper, the development of SiC power devices is introduced first; then, research statues and application prospects of SiC devices in electric vehicle are presented; last, the main problems of EV driving system using SiC power devices are discussed.", "author_names": [ "Wang Xueme" ], "corpus_id": 113139189, "doc_id": "113139189", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Researches and Applications of Wide Bandgap SiC Power Devices in Electric Vehicles", "venue": "", "year": 2014 }, { "abstract": "The automotive industry is developing a range of electrically powered environmentally friendly vehicles such as hybrid vehicles (HVs) plug in hybrid vehicles, full electric vehicles, and fuel cell vehicles to help reduce tailpipe CO2 emissions and achieve energy diversification. HVs are regarded as one of the most practical types of environmentally friendly vehicle and have already been widely accepted in the market. Toyota Motor Corporation has positioned HV systems as a core technology that can be applied to all next generation electrically powered environmentally friendly vehicles and is currently working to enhance the performance of HV system components. Because of its low loss and high temperature operation properties, silicon carbide (SiC) is regarded as a highly promising material for power semiconductor devices to help reduce the size and weight of the power control unit, one of the key components of a HV system. Wide ranging activities are under way to meet the challenges of adopting SiC in an automotive environment, such as the development of crystal growth technologies, device structures, process technologies, defect analysis, and application to on board systems. This paper describes the current situation and future prospects for on board SiC power devices and the development of SiC based technologies.", "author_names": [ "Kimimori Hamada", "Masaru Nagao", "Masaki Ajioka", "Fumiaki Kawai" ], "corpus_id": 20305493, "doc_id": "20305493", "n_citations": 115, "n_key_citations": 3, "score": 0, "title": "SiC Emerging Power Device Technology for Next Generation Electrically Powered Environmentally Friendly Vehicles", "venue": "IEEE Transactions on Electron Devices", "year": 2015 }, { "abstract": "This paper reviews the state of current electronics and states the drive toward high temperature electronics. The problems specific to high temperature effects on conventional electronics and prospects of alternative technologies like silicon on insulator, silicon carbide, and diamond are discussed. Improving petroleum recovery from oil wells with hightemperature coverage of downhole electronics, making combustion processes more efficient utilizing embedded electronics, programs for More Electric Aircraft and Vehicles necessitating distributed control systems, and environmental protection issues stress the need to use and develop high temperature electronics. This makes high temperature electronics a key enabling technology in the 21st century. Actual applications using high temperature electronics are discussed in some details. Also information and guidelines are included about supporting electronics needed to make a complete high temperature system. The technology has been making major advancements and is expected to account for 20% of the electronics market by 2010. However, many technical challenges have to be solved.", "author_names": [ "Farid Touati", "Faical Mnif", "Aqeela Al Lawati" ], "corpus_id": 110196267, "doc_id": "110196267", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "High Temperature Electronics: Status and Future Prospects in the 21st Century", "venue": "", "year": 2006 }, { "abstract": "1. Introduction Types of carbon nanotubes (CNTs) Synthesis of carbon nanotubes Importance of CNT metal nanocomposites Importance of CNT ceramic nanocomposites Current challenges in developing CNT reinforced metal and ceramic matrix nanocomposites 2. Carbon nanotube metal nanocomposites Processing of CNT metal nanocomposites Dispersion of CNTs in metals Interfaces in CNT metal nanocomposites Aluminum, magnesium and titanium based composites Microstructural characterization 3. Physical Properties of CNT metal nanocomposites Electrical behavior Percolation concentration 4. Mechanical characteristics of CNT metal nanocomposites Tensile deformation behavior Strengthening and toughening mechanism Structure property relationship Comparison with nanoparticle reinforced metals 5. Carbon nanotube ceramic nanocomposites Preparation of CNT ceramic nanocomposites Oxide based nanocomposites Alumina, magnesia, silica, titania and zirconia matrices Carbide based nanocomposites: Silicon carbide, boron carbide Nitride based nanocomposites: Silicon nitride Microstructural characterization 6. Physical Properties of CNT ceramic nanocomposites Electrical behavior Percolation concentration Thermal behavior 7. Mechanical characteristics of CNT ceramic nanocomposites Strengthening and toughening Microdeformation mechanism Fracture toughness 8. Conclusions Future prospects Potential applications of CNT metal nanocomposites Potential applications of CNT ceramic nanocomposites", "author_names": [ "Sie Chin Tjong" ], "corpus_id": 135679203, "doc_id": "135679203", "n_citations": 86, "n_key_citations": 3, "score": 0, "title": "Carbon Nanotube Reinforced Composites: Metal and Ceramic Matrices", "venue": "", "year": 2009 } ]

[ { "abstract": "Abstract H2 is an important energy carrier for replacing fossil fuel in the future due to its high energy density and environmental friendliness. As a sustainable H2 generation method, photocatalytic H2 production by water splitting has attracted much interest. Here, oil soluble ZnxCd1 xS quantum dot (ZCS QD) with a uniform particle size distribution were prepared by a hot injection method. However, no photocatalytic H2 production activity was observed for the oil soluble ZCS QD due to its hydrophobicity. Thus, the oil soluble ZCS QD was converted into a water soluble ZCS QD by a ligand exchange method. The water soluble ZCS QD exhibited excellent photocatalytic H2 production performance in the presence of glycerin and Ni2+ with an apparent quantum efficiency of 15.9% under irradiation of 420 nm light. Further, the photocatalytic H2 generation activity of the ZCS QD was ~10.7 times higher than that of the ZnxCd1 xS relative samples prepared by the conventional co precipitation method. This work will inspire the design and fabrication of other semiconductor QD photocatalysts because QD exhibits excellent separation efficiency for photogenerated electron hole pairs due to its small crystallite size.", "author_names": [ "Rongrong Gao", "Bei Cheng", "Jiajie Fan", "Jiaguo Yu", "Wingkei Ho" ], "corpus_id": 224959607, "doc_id": "224959607", "n_citations": 19, "n_key_citations": 0, "score": 1, "title": "Zn Cd1 S quantum dot with enhanced photocatalytic H2 production performance", "venue": "", "year": 2021 }, { "abstract": "Quantum gates between spin qubits can be implemented leveraging the natural Heisenberg exchange interaction between two electrons in contact with each other. This interaction is controllable by electrically tailoring the overlap between electronic wave functions in quantum dot systems, as long as they occupy neighboring dots. An alternative route is the exploration of superexchange the coupling between remote spins mediated by a third idle electron that bridges the distance between quantum dots. We experimentally demonstrate direct exchange coupling and provide evidence for second neighbor mediated superexchange in a linear array of three single electron spin qubits in silicon, inferred from the electron spin resonance frequency spectra. We confirm theoretically, through atomistic modeling, that the device geometry only allows for sizable direct exchange coupling for neighboring dots, while next nearest neighbor coupling cannot stem from the vanishingly small tail of the electronic wave function of the remote dots, and is only possible if mediated.", "author_names": [ "Kok Wai Chan", "Harshad Sahasrabudhe", "Wister Huang", "Henry Yang", "Menno Veldhorst", "Jason C C Hwang", "Fahd A Mohiyaddin", "Fay E Hudson", "Kohei M Itoh", "Andre Saraiva", "Andrea Morello", "Arne Laucht", "Rajib Rahman", "Andrew S Dzurak" ], "corpus_id": 215786145, "doc_id": "215786145", "n_citations": 6, "n_key_citations": 1, "score": 0, "title": "Exchange Coupling in a Linear Chain of Three Quantum Dot Spin Qubits in Silicon.", "venue": "Nano letters", "year": 2021 }, { "abstract": "Interleukin 6 (IL 6) acts as both a proinflammatory and anti inflammatory cytokine and is generally utilized as an important diagnostic biomarker for sepsis. In addition, the high levels of IL 6 measured in plasma have been associated with pathological inflammation. A novel quartz crystal microbalance (QCM) immunoassay method was presented for high sensitivity and selectivity detection of interleukin 6 (IL 6) based on gold nanoparticles functionalized sulfur doped graphene quantum dot (AuNPs/S GQD) and hollow ZnS CdS nanocage (h ZnS CdS NC) Firstly, AuNPs/S GQD nanocomposite was synthesized in the presence of tetrachloroauric acid and then conjugated onto anti IL 6 antibodies by amino gold affinity. The sandwich type QCM immunoassay probe was prepared by immune reaction between AuNPs/S GQD/QCM immobilized with anti IL 6 capture antibodies and h ZnS CdS NC including detection anti IL 6 antibodies in the presence of target IL 6. The prepared QCM immunoassay probe was characterized by transmission electron microscopy (TEM) scanning electron microscope (SEM) x ray diffraction (XRD) method, x ray photoelectron spectroscopy (XPS) Raman spectroscopy, UV vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) The QCM immunosensor showed a linearity range (0.01 2.0 pg mL 1) and a low detection limit (3.33 fg mL 1) Lastly, high stable and selective QCM immunosensor was applied to prepared plasma samples with good recovery.", "author_names": [ "Necip Atar", "Mehmet Lutfi Yola" ], "corpus_id": 231752426, "doc_id": "231752426", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "A novel QCM immunosensor development based on gold nanoparticles functionalized sulfur doped graphene quantum dot and h ZnS CdS NC for Interleukin 6 detection.", "venue": "Analytica chimica acta", "year": 2021 }, { "abstract": "Abstract Exploring electrocatalysts with optimal electronic structure and understanding the relationship between electronic structure and activity are highly required for designing advanced OER catalysts. Recently, introducing nanocarbon materials into LDHs has been demonstrated as an effective way to improve the OER activity; however, deeply understanding the regulating effect of nanocarbon on the electronic structure of LDHs is still a critical challenge. Herein, it is reported that the regulating of the surface electronic structure of nickel based layered double hydroxides (NiM LDHs (M Fe, Co, Mn) by adsorbing graphene quantum dot (GQDs) The Ni based LDHs/GQDs delivers enhanced OER activity, and particularly NiFe LDH/GQDs achieves an ultralow overpotential of 189 mV (10 mA cm 2) and superior performance in rechargeable Zn air battery tests. Combining with theoretical calculations and X ray photoelectron spectroscopy, we ascribe the excellent OER activity of Ni based LDHs/GQDs to the strong interaction between NiFe LDH and GQDs, which changes the charge distribution around metal ions and triggers the charge accumulation of the active Ni species. The above results demonstrate the significance of controlling the surface electronic structure for designing advanced 3d metal electrocatalysts.", "author_names": [ "Xingqun Zheng", "Xiaoling Hu", "Qiannan Zhao", "Peng Yu", "Chuan Jing", "Yuxin Zhang", "Guangsheng Huang", "Bin Jiang", "Chaohe Xu", "Fu-sheng Pan" ], "corpus_id": 233545751, "doc_id": "233545751", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Electrostatic adsorbing graphene quantum dot into nickel based layered double hydroxides: Electron absorption/donor effects enhanced oxygen electrocatalytic activity", "venue": "", "year": 2021 }, { "abstract": "Graphical abstract This perspective describes the advances and challenges of emerging perovskite quantum dot solar cells. The strategies on ligand capping, defect passivation, and composition engineering together with future prospects are discussed. Download Download high res image (197KB) Download Download full size image", "author_names": [ "Aili Wang", "Zhiwen Jin", "Ming Cheng", "Feng Hao", "Liming Ding" ], "corpus_id": 219492172, "doc_id": "219492172", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Advances in perovskite quantum dot solar cells", "venue": "", "year": 2021 }, { "abstract": "All inorganic CsPbI 3 perovskite quantum dots have received substantial research interest for photovoltaic applications because of higher efficiency compared to solar cells using other quantum dots materials and the various exciting properties that perovskites have to offer. These quantum dot devices also exhibit good mechanical stability amongst various thin film photovoltaic technologies. We demonstrate higher mechanical endurance of quantum dot films compared to bulk thin film and highlight the importance of further research on high performance and flexible optoelectronic devices using nanoscale grains as an advantage. Specifically, we develop a hybrid interfacial architecture consisting of CsPbI 3 quantum dot/PCBM heterojunction, enabling an energy cascade for efficient charge transfer and mechanical adhesion. The champion CsPbI 3 quantum dot solar cell has an efficiency of 15.1% (stabilized power output of 14.61% which is among the highest report to date. Building on this strategy, we further demonstrate a highest efficiency of 12.3% in flexible quantum dot photovoltaics. Perovskite quantum dots film has better mechanical stability and structural integrity compared to bulk thin film. Here, the authors demonstrate higher endurance of quantum dot films and develop hybrid CsPbI3 QD/PCBM device with PCE of 15.1% and 12.3% on rigid and flexible substrates, respectively.", "author_names": [ "Long Hu", "Qian Zhao", "Shujuan Huang", "Jianghui Zheng", "Xinwei Guan", "Robert J Patterson", "Jiyun Kim", "Lei Shi", "Chun-Ho Lin", "Qi Lei", "Dewei Chu", "Wan Tao", "Soshan Cheong", "Richard D Tilley", "Anita W Y Ho-baillie", "Joseph M Luther", "Jianyu Yuan", "Tom Wu" ], "corpus_id": 231665921, "doc_id": "231665921", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Flexible and efficient perovskite quantum dot solar cells via hybrid interfacial architecture", "venue": "Nature communications", "year": 2021 }, { "abstract": "Quantum key distribution is demonstrated over an urban open air link using entangled light from a semiconductor nanostructure. Quantum key distribution exchanging a random secret key relying on a quantum mechanical resource is the core feature of secure quantum networks. Entanglement based protocols offer additional layers of security and scale favorably with quantum repeaters, but the stringent requirements set on the photon source have made their use situational so far. Semiconductor based quantum emitters are a promising solution in this scenario, ensuring on demand generation of near unity fidelity entangled photons with record low multiphoton emission, the latter feature countering some of the best eavesdropping attacks. Here, we use a coherently driven quantum dot to experimentally demonstrate a modified Ekert quantum key distribution protocol with two quantum channel approaches: both a 250 m long single mode fiber and in free space, connecting two buildings within the campus of Sapienza University in Rome. Our field study highlights that quantum dot entangled photon sources are ready to go beyond laboratory experiments, thus opening the way to real life quantum communication.", "author_names": [ "Francesco Basso Basset", "Mauro Valeri", "Emanuele Roccia", "Valerio Muredda", "Davide Poderini", "Julia Neuwirth", "Nicolo Spagnolo", "Michele B Rota", "Gonzalo Carvacho", "Fabio Sciarrino", "Rinaldo Trotta" ], "corpus_id": 220793370, "doc_id": "220793370", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Quantum key distribution with entangled photons generated on demand by a quantum dot", "venue": "Science Advances", "year": 2021 }, { "abstract": "Abstract Quantum dot light emitting diodes (QLEDs) are unarguably the most successful member of rapidly developing family of devices based on quantum dots (type II VI group compounds) Herein, the electroluminescence properties and fabrication/characterization technologies of QLEDs are reviewed. Particular emphasis is devoted to the dynamic processes of charge carriers and the related characterization technology because QLEDs are electro optic conversion devices whose performance is to a great extent determined by the carrier transport/distribution and exciton formation. The utility of spectroscopic technologies, including steady/transient electroluminescence and photoluminescence, electro absorption spectrum, and differential absorption spectrum are explained. Additionally, displacement current measurement technology is also discussed due to its potential to characterize the trapped charges within the devices. The strategies to improve the device performance by interface modification and QD design are summarized and the corresponding physics and chemistry mechanisms are discussed. Finally, a summary and outlook are shown about the challenge faced by QLED, as well as possible pathway to enhancing the device performance.", "author_names": [], "corpus_id": 234315757, "doc_id": "234315757", "n_citations": 5, "n_key_citations": 1, "score": 1, "title": "A review on the electroluminescence properties of quantum dot light emitting diodes", "venue": "", "year": 2021 }, { "abstract": "Abstract Transition metal oxides are one of the promising materials for energy storage because they have rich redox reactions with good stability. In this study, CuMnO2 nanocrystals and CuMnO2/graphene quantum dot (GQD) composite were synthesized by hydrothermal method and used in constructing a new supercapacitor. GQD has been applied to increase specific capacity and improve efficiency of the supercapacitor. Various methods were used to identify the synthesized nanocomposite and to study its morphology, structure and surface area. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to record and track the electrochemical behavior of the synthesized nanocomposite used as an electrode material. The study of changes in the capacity of CuMnO2/GQD and CuMnO2 electrodes during 5000 consecutive charge/discharge cycles showed that the stability of the electrode made of nanocomposite is higher and its capacity after this number of cycles reached 83.3% while the capacity of the electrode made with CuMnO2 nanoparticles has reached 65.4% The specific capacity of CuMnO2/GQD nanocomposite and CuMnO2 nanoparticles at a current density of 1 A g 1 was calculated to be 520.2 and 381.5 C g 1, respectively. The maximum specific energy of CuMnO2/GQD//AC asymmetric supercapacitor was obtained at a specific power of 1108.1 W kg 1 equal to 47.9 Wh Kg 1. Asymmetric supercapacitor capacitance decreased by only less than 13.3% after 5000 charge and discharge cycles, which is a very good cycle life compared to similar materials. All these results indicate that the CuMnO2/GQD nanocomposite can be deliberated as a possible option for fast and stable supercapacitor.", "author_names": [ "Mohammad Ashourdan", "Abolfazl Semnani", "Foroozan Hasanpour", "Seyyed Ebrahim Moosavifard" ], "corpus_id": 233591939, "doc_id": "233591939", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Synthesis of CuMnO2/graphene quantum dot nanocomposites as novel electrode materials for high performance supercapacitors", "venue": "", "year": 2021 }, { "abstract": "We investigate room temperature lasing of terahertz quantum cascade lasers using quantum dot chains as active material suitable for wireless communication and imaging technologies. To make band structure calculations for such extended systems of coupled quantum dots possible, we developed a `linear combination of quantum dot orbitals' method, based on single quantum dot wave functions. Our results demonstrate strong vertical emission of coupled quantum dots, reduced phonon coupling, and in plane scattering, enabling room temperature lasing with significantly reduced threshold current densities.", "author_names": [ "Alexander Mittelstadt", "Ludwig A Th Greif", "Stefan Thomas Jagsch", "Andrei Schliwa" ], "corpus_id": 234354425, "doc_id": "234354425", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Terahertz lasing at room temperature: A numerical study of a vertical emitting quantum cascade laser based on a quantum dot superlattice", "venue": "", "year": 2021 } ]

[ { "abstract": "Part 1 Policy context for US trade: introduction US trade negotiations in perspective, Robert S. Walters the multilateral trade order the new GATT round, Charles Pearson and Mils Johnson the domestic political setting of US trade policy, Timothy J.C. O'Shea. Part 2 US trade diplomacy: the US Japan semiconductor problem, Timothy J.C. O'Shea under construction US Japan negotiations to open Japan's construction markets to American firms, Ellis Krauss the US Brazilian informatics dispute, Ellene Felder and Andrew Hurrell European Community enlargement and the United States, John Odell and Margit Matzinger Tchakerian.", "author_names": [ "Robert S Walters" ], "corpus_id": 152656048, "doc_id": "152656048", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Talking Trade", "venue": "", "year": 2020 }, { "abstract": "", "author_names": [ "Ellene A Felder", "Andrew Hurrell" ], "corpus_id": 144828456, "doc_id": "144828456", "n_citations": 4, "n_key_citations": 0, "score": 1, "title": "The U.S. Brazilian informatics dispute", "venue": "", "year": 1991 }, { "abstract": "This is one of the finest books on the normative dimension of global governance published in the past decade. Utilizing insights from the English School, liberal institutionalism, and constructivism, the author addresses some of the most profound questions on the nature, limitations, and possibilities of global order in the twenty first century. Andrew Hurrell, a former student of Hedley Bull, goes beyond the traditional concept of an anarchical society based on minimalist conditions of coexistence and suggests a fresh approach to understanding what kinds of political organizations we need in the future. To do so, he explores three major challenges in global society: the need to capture shared and common interests, the imperative to manage unequal power, and the need to mediate cultural diversity and value conflict. On Global Order is divided into four parts. The first, which focuses on conceptual frameworks, comprises three chapters that revisit the idea of the anarchical society, explore global liberalism, and analyze the complex system of global governance. Hurrell regards the anarchical society identified by Bull and others in the English School which rested on the preservation of international society, the maintenance of the independence of sovereign states, and the regulation of war and conflict", "author_names": [ "Samuel M Makinda" ], "corpus_id": 144657348, "doc_id": "144657348", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "On Global Order: Power, Values, and the Constitution of International Society by Andrew Hurrell", "venue": "Ethics International Affairs", "year": 2009 }, { "abstract": "", "author_names": [ "Ian D Clark" ], "corpus_id": 143820921, "doc_id": "143820921", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "On Global Order: Power, Values, and the Constitution of International Society By Andrew Hurrell. New York: Oxford University Press, 2007. 354p. $95.00 cloth, $35.00 paper.", "venue": "Perspectives on Politics", "year": 2008 }, { "abstract": "", "author_names": [ "Robert M Pallitto" ], "corpus_id": 154117911, "doc_id": "154117911", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "On Global Order: Power, Values, and the Constitution of International Societyby Andrew Hurrell", "venue": "", "year": 2008 }, { "abstract": "Catalysis informatics is a distinct subfield that lies at the intersection of cheminformatics and materials informatics but with distinctive challenges arising from the dynamic, surface sensitive, and multiscale nature of heterogeneous catalysis. The ideas behind catalysis informatics can be traced back decades, but the field is only recently emerging due to advances in data infrastructure, statistics, machine learning, and computational methods. In this work, we review the field from early works on expert systems and knowledge engines to more recent approaches utilizing machine learning and uncertainty quantification. The data information knowledge hierarchy is introduced and used to classify various developments. The chemical master equation and microkinetic models are proposed as a quantitative representation of catalysis knowledge, which can be used to generate explanative and predictive hypotheses for the understanding and discovery of catalytic materials. We discuss future prospects for the field, i.", "author_names": [ "Andrew J Medford", "M Ross Kunz", "Sarah M Ewing", "Tammie L Borders", "Rebecca R Fushimi" ], "corpus_id": 104233691, "doc_id": "104233691", "n_citations": 81, "n_key_citations": 0, "score": 0, "title": "Extracting Knowledge from Data through Catalysis Informatics", "venue": "", "year": 2018 }, { "abstract": "We introduce a combination of existing and novel approaches to the assessment and prediction of particle properties intrinsic to the formulation and manufacture of pharmaceuticals. Naturally following on from established solid form informatics methods, we return to the drug lamotrigine, re evaluating its context in the Cambridge Structural Database (CSD) We then apply predictive digital design tools built around the CSD System suite of software, including Synthonic Engineering methods that focus on intermolecular interaction energies, to analyze and understand important particle properties and their effects on several key stages of pharmaceutical manufacturing. We present a new, robust workflow that brings these approaches together to build on the knowledge gained from each step and explain how this knowledge can be combined to provide resolutions at decision points encountered during formulation design and manufacturing processes.", "author_names": [ "M J Bryant", "Ian Rosbottom", "Ian J Bruno", "R Docherty", "Colin M Edge", "Robert B Hammond", "R H Peeling", "Jonathan Pickering", "Kevin J Roberts", "Andrew G P Maloney" ], "corpus_id": 202073713, "doc_id": "202073713", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "\"Particle Informatics\" Advancing Our Understanding of Particle Properties through Digital Design", "venue": "Crystal Growth Design", "year": 2019 }, { "abstract": "", "author_names": [ "Chuan Ming Gang" ], "corpus_id": 160847658, "doc_id": "160847658", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Shao Jie Rosemary Foot, John Lewis Gaddis and Andrew Hurrell(eds. Order and Justice in International Relations", "venue": "", "year": 2004 }, { "abstract": "", "author_names": [ "Imtiaz Hussain" ], "corpus_id": 147024161, "doc_id": "147024161", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Regionalism in World Politics: Regional Organization and international order, de Louise Fawcett y Andrew Hurrell", "venue": "", "year": 1998 }, { "abstract": "Adverse drug reactions have been linked with HLA alleles in different studies. These HLA proteins play an essential role in the adaptive immune response for the presentation of self and non self peptides. Anti thyroid drugs methimazole and propylthiouracil have been associated with drug induced agranulocytosis (severe lower white blood cell count) in patients with B*27:05, B*38:02 and DRB1*08:03 alleles in different populations: Taiwanese, Vietnamese, Han Chinese and Caucasian. In this study, informatics methods were used to investigate if any sequence or structural similarities exist between the two associated HLA B alleles, compared with a set of \"control\" alleles assumed not be associated, which could help explain the molecular basis of the adverse drug reaction. We demonstrated using MHC Motif Viewer and MHCcluster that the two alleles do not have a propensity to bind similar peptides, and thus at a gross level the structure of the antigen presentation region of the two alleles are not similar. We also performed multiple sequence alignment to identify polymorphisms shared by the risk but not by the control alleles and molecular docking to compare the predicted binding positions of the drug allele combinations. Two residues, Cys67 and Thr80, were identified from the multiple sequence alignments to be unique to these risk alleles alone. The molecular docking showed the poses of the risk alleles to favour the F pocket of the peptide binding groove, close to the Thr80 residue, with the control alleles generally favouring a different pocket. The data are thus suggestive that Thr80 may be a critical residue in HLA mediated anti thyroid drug induced agranulocytosis, and thus can guide future research and risk assessment.", "author_names": [ "Kerry A Ramsbottom", "Daniel F Carr", "Daniel J Rigden", "Andrew R Jones" ], "corpus_id": 199638835, "doc_id": "199638835", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Informatics investigations into anti thyroid drug induced agranulocytosis associated with multiple HLA B alleles", "venue": "", "year": 2019 } ]

[ { "abstract": "Unconventional thermo optic responses of CH3NH3PbCl3 enable phase shift compensators and tunable retarders for visible light. Lead halide perovskites are promising semiconductors for high performance photonic devices. Because the refractive index determines the optimal design and performance limit of the semiconductor devices, the refractive index and its change upon external modulations are the most critical properties for advanced photonic applications. Here, we report that the refractive index of halide perovskite CH3NH3PbCl3 shows a distinct decrease with increasing temperature, i.e. a large negative thermo optic coefficient, which is opposite to those of conventional inorganic semiconductors. By using this negative coefficient, we demonstrate the compensation of thermally induced optical phase shifts occurring in conventional semiconductors. Furthermore, we observe a large and slow refractive index change in CH3NH3PbCl3 during photoirradiation and clarify its origin to be a very low thermal conductivity supported by theoretical analysis. The giant thermo optic response of CH3NH3PbCl3 facilitates efficient phase modulation of visible light.", "author_names": [ "Taketo Handa", "Hirokazu Tahara", "Tomoko Aharen", "Yoshihiko Kanemitsu" ], "corpus_id": 198120457, "doc_id": "198120457", "n_citations": 20, "n_key_citations": 0, "score": 1, "title": "Large negative thermo optic coefficients of a lead halide perovskite", "venue": "Science Advances", "year": 2019 }, { "abstract": "Abstract Chalcogenide glasses have attracted much attention for the realization of photonic components owing to their outstanding optical properties in the mid infrared (MIR) region. However, relatively few refractive index dispersion data are presently available for these glasses at MIR wavelengths. This paper presents a mini review of methods we have both used and developed to determine the refractive indices and thermo optic coefficients of chalcogenide glasses at MIR wavelengths, and is supported by new results. The mini review should be useful to both new and established researchers in the chalcogenide glass field and fields of MIR optics, fiber optics and waveguides. Three groups of methods are distinguished: (1) spectroscopic ellipsometry, (2) prism based methods, and (3) methods using Fourier transform infrared (FTIR) transmission data. The mini review is supported by a brief discussion of refractive index models.", "author_names": [ "Y Fang", "David Furniss", "Dinuka Jayasuriya", "Harriet Parnell", "Z Q Tang", "Daniel J Gibson", "Shyam S Bayya", "Jas S Sanghera", "Angela B Seddon", "T M Benson" ], "corpus_id": 202983186, "doc_id": "202983186", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "(INVITED) Methods for determining the refractive indices and thermo optic coefficients of chalcogenide glasses at MIR wavelengths", "venue": "Optical Materials: X", "year": 2019 }, { "abstract": "A new method (FTIR continuous dn dT method, n is refractive index and T temperature) for measuring the continuous thermo optic coefficients of thin transparent films in the mid infrared (MIR) spectral region is introduced. The technique is based on Fourier transform infrared (FTIR) transmission spectra measured at different temperatures. It is shown that this method can successfully determine the thermo optic coefficient of chalcogenide glass thin films (of batch compositions Ge20Sb10Se70 at. (atomic and Ge16As24Se15.5Te44.5 at. over the wavelength range from 2 to 25 um. The measurement precision error is less than 11.5 ppm degC over the wavelength range from 6 to 20 um. The precision is much better than that provided by the prism minimum deviation method or an improved Swanepoel method.", "author_names": [ "Yuanrong Fang", "David Furniss", "Dinuka Jayasuriya", "Harriet Parnell", "Zhuoqi Tang", "Angela B Seddon", "Trevor M Benson" ], "corpus_id": 199686852, "doc_id": "199686852", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Determining the continuous thermo optic coefficients of chalcogenide glass thin films in the MIR region using FTIR transmission spectra.", "venue": "Optics express", "year": 2019 }, { "abstract": "Abstract Terahertz time domain spectroscopy has been used to measure the temperature dependent absorption coefficients and refractive indices of different polymers in 0.2 1.8 THz spectral frequency. The coefficients of temperature dependent Sellmeier equation for all these polymers have also been evaluated by statistical fitting the measured data, which will be helpful for the evaluation of dispersion properties of the material. Additionally, the thermo optic coefficients have been evaluated to be the range of 1.230 x 10 4 to 2.50 x 10 4 K 1 for 298 373 K. This data would be helpful for the applications of polymers as THz waveguide and other temperature sensitive devices. These results provide a temperature dependent database of optical properties of different polymers for their efficient utilization in THz technology.", "author_names": [ "Muhammad Bilal Mumtaz", "M Ahsan Mahmood", "Sabih D Khan", "M Aslam Zia", "Mushtaq Ahmed", "Izhar Ahmad" ], "corpus_id": 109294660, "doc_id": "109294660", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Experimental measurement of temperature dependent sellmeier coefficients and thermo optic coefficients of polymers in terahertz spectral range", "venue": "Optical Materials", "year": 2019 }, { "abstract": "The values of dn/dT for thermally evaporated WO3 thin films were found to be negative either in the heating cycle (295 373 K) or in the cooling cycle (100 300 K) and were found to be of order of 10 5 K 1. On the other hand thermo optic coefficients (TOCs: dn/dT and dk/dT values) of tungsten bronzes (H+ Li+ Na+ with different concentrations were found to be positive and negative, respectively in both the heating and cooling cycles and they were found to be in the order of 10 4 K 1. Heating cycles show hysteresis loops of n and k for tungsten bronzes, which are good for electrochromic devices. On heating the bronzes at temperature higher than 400 K, there might be a reduction in the porosity but an irreversible disordering of hydrogen, lithium or sodium atoms could occur because of anomalous dispersions produced in the optical data. For cooling cycles, the calculated TOCs were again of the order of 10 4 but there was an increase in dn/dT and a decrease in dk/dT values due to more amorphousness built up in the bronzes during the cooling cycles. This change in the values of TOCs for tungsten bronzes created small decrease in electronic polarizabilities (ae) which were calculated in the range from 8.003 to 8.02 x 10 24 cm3 in the cooling cycles.", "author_names": [ "Zahid Hussain" ], "corpus_id": 204196693, "doc_id": "204196693", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Thermo Optic Coefficients and Electronic Polarizabilities of Tungsten Bronzes Using Ellipsometry", "venue": "IEEE Photonics Journal", "year": 2019 }, { "abstract": "We have measured mass densities, thermo optic coefficients, and electronic polarizability of MoO3 thin films and of HxMoO3 and LixMoO3 bronze thin films over the temperature range from 100 K to 373 K using ellipsometry. The mass densities of MoO3 and molybdenum bronzes with different concentrations (x) changed from 3.76 g/cm3 to 2.45 g/cm3 during the heating and cooling cycles. Thermo optic coefficients (TOCs) or dn/dT and dk/dT values of the molybdenum bronzes were found to have anomalous dispersion in the heating cycles over the range 295 373 K. On the other hand, the values of dn/dT for MoO3 thin films and for ZxMoO3 bronzes were found to be negative and positive, respectively over the temperature range 100 295 K and were on the order of 10 4 K 1. The respective values of dk/dT were found to be positive and negative and were on the order of 10 4 K 1 in the same temperature range. A little increase in the values of TOCs for the molybdenum bronzes is due to small increase in electronic polarizability, which was calculated in the range from 8.20 to 8.22 x 10 24 cm3 over the temperature range 100 373 K. All these small values are due to creation of more amorphousness in the MoO3 structure during the cooling cycles. The n and k data and TOCs values of molybdenum bronzes are explained using analytical model. The reported ellipsometric data is also interpreted in terms of small polarons and bipolarons using configurational coordinate model.", "author_names": [ "Zahid Hussain" ], "corpus_id": 201656267, "doc_id": "201656267", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Ellipsometric Investigations of Electronic Polarizability and Thermo optic Coefficients of ZxMoO3 (Z H+ Li+ Bronzes", "venue": "Journal of Electronic Materials", "year": 2019 }, { "abstract": "Abstract The development of thermo optic modulator elements for midwave infrared (MWIR) and longwave infrared (LWIR) electro optic systems, and the development of resistive thermometer elements for infrared imaging microbolometers require materials with high thermo optic coefficients (TOC) and high temperature coefficients of resistance (TCR) respectively. In this paper, we synthesize novel vanadium oxide (VxOy) thin film structures and measure their MWIR/LWIR thermo optic coefficients (TOCs) and their temperature coefficients of resistance (TCRs) The VxOy thin film are synthesized by sputter depositing interchanging, 5 nm thick, layers of vanadium sesquioxide (V2O3) and vanadium (V) reaching a final thin film thickness of 95 nm. The sputter deposited multilayer structures are then ex situ annealed in N2 and O2 atmospheres at 300 degC for 30 min. Infrared spectroscopic ellipsometry was used to measure the optical constants of the thin films as a function of temperature across the MWIR and LWIR bands (3000 14000 nm) The synthesized VxOy thin films exhibited high TOCs and high TCRs when operated in their semiconducting phase. A high TOC was measured reaching a maximum of 0.0278 degC 1 and 0.119 degC 1 at l 4000 nm for N2 and O2 annealed VxOy thin films respectively; and reaching a maximum of 0.0634 degC 1 and 0.139 degC 1 at l 10,000 nm for N2 and O2 annealed VxOy thin films respectively. Moreover, sheet resistance versus temperature measurements were conducted revealing room temperature sheet resistances of 1.495 k O/sq. and 1.516 k O/sq. and TCRs of 3.54%/degC and 3.46%/degC for N2 and O2 annealed VxOy thin films respectively.", "author_names": [ "Mohamed R Abdel-Rahman" ], "corpus_id": 125974018, "doc_id": "125974018", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Vanadium oxide thin films with high midwave longwave infrared thermo optic coefficients and high temperature coefficients of resistance", "venue": "", "year": 2018 }, { "abstract": "A microcavity fiber Fabry Perot interferometer (MFFPI) that is based on dual hollow core fibers (HCFs) is developed for measuring the thermo optic coefficients (TOCs) of liquids. The proposed MFFPI was fabricated by fusion splicing a tiny segment of the main HCF with a diameter D of 30 mm and another section of feeding HCF with a diameter of 5 mm. Then, the main HCF was filled with liquid by capillary action through the feeding HCF by immersing the MFFPI in the liquid. The TOCs of the Cargille liquid (n(D)=1.3) deionized (DI) water, and ethanol were accurately determined from the shift of the interference wavelength, which was due to the temperature variation. Our experimental results were also compared with other published studies to investigate the effectiveness of the proposed sensing scheme. The major advantage is that the miniature MFFPI can achieve the measurement of the TOCs of the liquids with picoliter volume, and the measured liquids also can be sealed off and stored inside the HCF to prevent contamination.", "author_names": [ "Cheng-Ling Lee", "Hsuan-Yu Ho", "Jheng-Hong Gu", "Tung-Yuan Yeh", "Chung-Hao Tseng" ], "corpus_id": 36465809, "doc_id": "36465809", "n_citations": 46, "n_key_citations": 1, "score": 0, "title": "Dual hollow core fiber based Fabry Perot interferometer for measuring the thermo optic coefficients of liquids.", "venue": "Optics letters", "year": 2015 }, { "abstract": "We report a method for compensation of errors caused by temperature fluctuations in refractive index measurements using Silicon photonic microring sensors. The method involves determination of resonance wavelength shifts caused by thermal fluctuations using real time measurement of on chip temperature variations and thermo optic coefficient (TOC) of analyte liquids. Resistive metal lines patterned around Silicon microrings are used to track temperature variations and TOC of analyte is calculated by measuring wavelength shifts caused by controlled increments in device temperature. The TOC of de ionized water is determined to be 1.12 x 10 4/degC, with an accuracy of 8.26 x 10 6/degC. In our system, chip surface temperature variations were measured with an instrument limited precision of 0.004 degC yielding a factor of 16 enhancement in tracking accuracy compared to conventional, bottom of chip temperature measurement. We show that refractive index detection limit of the microring sensor is also improved by the same factor.", "author_names": [ "Prashanth R Prasad", "Shankar Kumar Selvaraja", "Manoj M Varma" ], "corpus_id": 44137328, "doc_id": "44137328", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Real time compensation of errors in refractive index shift measurements of microring sensors using thermo optic coefficients.", "venue": "Optics express", "year": 2018 }, { "abstract": "Seventeen glasses in the Ge As Se ternary glass forming region have been fabricated and analyzed to provide input for optical design data and to establish composition and structure based relationships to aide development of novel chalcogenide glasses with tailored optical functionality. While known that Ge addition to binary As Se glasses enhances the mean coordination number (MCN) of the network and results in increased Tg and decreased CTE, this work highlights the impact on optical properties, specifically mid wave (l 4.515 mm) index and thermo optic coefficient (dn/dT) Trends in property changes were correlated with an excess or deficiency of chalcogen content in the glassy network as compared to stoichiometric compositions. Transitions in key optical properties were observed with the disappearance of Se Se homopolar bonds and creation of As As homopolar bonds which are associated with the Se rich and Se deficient regions near the stoichiometry, respectively. A second transition was observed with the creation of GeSe ethane like structures, which are only present in strongly Se deficient networks. Fitting dn/dT values with a simplified version of the thermal Lorentz Lorenz formulation yielded a linear relation between the quantity (n 3dn/dT) and the CTE, which can be used to predict compositions with the near zero dn/dT required for athermal optical systems.", "author_names": [ "Benn Gleason", "Kathleen Richardson", "Laura Sisken", "Charmayne E Smith" ], "corpus_id": 139079603, "doc_id": "139079603", "n_citations": 32, "n_key_citations": 1, "score": 0, "title": "Refractive Index and Thermo Optic Coefficients of Ge As Se Chalcogenide Glasses", "venue": "", "year": 2016 } ]

[ { "abstract": "Semiconductor photocatalysis is a promising approach to combat both environmental pollution and the global energy shortage. Advanced TiO2 based photocatalysts with novel photoelectronic properties are benchmark materials that have been pursued for their high solar energy conversion efficiency. In general, the photocatalytic efficiency is affected by the degree of light absorption, charge separation, and surface reactivity. Consequently, in this review we first discuss a series of interesting studies that aim to extend the light absorption of TiO2 from UV wavelengths into the visible or even the near infrared region. We next focus on attempts to overcome the drawback that dopants usually act as charge recombination centres. We discuss the use of either selective local doping or the introduction of disorder together with doping, which aims to facilitate charge separation while preserving the visible light response. We also show that crystal facet engineering can endow TiO2 with superior physicochemical properties, thus yielding high surface reactivity in photocatalytic reactions. Finally, we examine the recent theoretical advances of TiO2 based photocatalysis.", "author_names": [ "Hua Xu", "Shuxin Ouyang", "Lequan Liu", "Pakpoom Reunchan", "Naoto Umezawa", "Jinhua Ye" ], "corpus_id": 136121316, "doc_id": "136121316", "n_citations": 16, "n_key_citations": 0, "score": 1, "title": "Recent advances in TiO 2 based photocatalysis", "venue": "", "year": 2014 }, { "abstract": "Hierarchical TiO2 superstructures with desired architectures and intriguing physico chemical properties are considered to be one of the most promising candidates for solving the serious issues related to global energy exhaustion as well as environmental deterioration via the well known photocatalytic process. In particular, TiO2 mesocrystals, which are built from TiO2 nanocrystal building blocks in the same crystallographical orientation, have attracted intensive research interest in the area of photocatalysis owing to their distinctive structural properties such as high crystallinity, high specific surface area, and single crystal like nature. The deeper understanding of TiO2 mesocrystals based photocatalysis is beneficial for developing new types of photocatalytic materials with multiple functionalities. In this paper, a comprehensive review of the recent advances toward fabricating and modifying TiO2 mesocrystals is provided, with special focus on the underlying mesocrystallization mechanism and controlling rules. The potential applications of as synthesized TiO2 mesocrystals in photocatalysis are then discussed to shed light on the structure performance relationships, thus guiding the development of highly efficient TiO2 mesocrystal based photocatalysts for certain applications. Finally, the prospects of future research on TiO2 mesocrystals in photocatalysis are briefly highlighted.", "author_names": [ "Boxue Zhang", "Shengxin Cao", "Meiqi Du", "Xiaozhou Ye", "Yun Wang", "Jianfeng Ye" ], "corpus_id": 202662652, "doc_id": "202662652", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Titanium Dioxide TiO 2 Mesocrystals Synthesis Growth Mechanisms and Photocatalytic Properties", "venue": "", "year": 2019 }, { "abstract": "Photocatalysis, which is the catalyzation of redox reactions via the use of energy obtained from light sources, is a topic that has garnered a lot of attention in recent years as a means of addressing the environmental and economic issues plaguing society today. Of particular interest are photosynthesis can potentially mimic a variety of vital reactions, many of which hold the key to develop sustainable energy economy. In light of this, many of the technological and procedural advancements that have recently occurred in the field are discussed in this review, namely those linked to: (1) photocatalysts made from metal oxides, nitride, and sulfides; (2) photocatalysis via polymeric carbon nitride (PCN) and (3) general advances and mechanistic insights related to TiO 2 based catalysts. The challenges and opportunities that have arisen over the past few years are discussed in detail. Basic concepts and experimental procedures which could be useful for eventually overcoming the problems associated with photo catalysis are presented herein.", "author_names": [ "Yuanxing Fang", "Yun Zheng", "Tao Fang", "Yong Chen", "Yaodong Zhu", "Qing Liang", "Hua Sheng", "Zhaosheng Li", "Chuncheng Chen", "Xinchen Wang" ], "corpus_id": 209542157, "doc_id": "209542157", "n_citations": 30, "n_key_citations": 0, "score": 0, "title": "Photocatalysis: an overview of recent developments and technological advancements", "venue": "Science China Chemistry", "year": 2019 }, { "abstract": "Fundamental mechanisms of TiO(2) heterogeneous photocatalysis for degrading wastes are based on some radical reactions. Under ultraviolet light the photocatalysts produce holes and electrons, which subsequently initiate oxidation and reduction reactions. Holes and electrons can react directly with organic species adsorbed on the surface of the catalysts and also can transform into high energy chemical species such as hydroxyl radicals. Some organics such as dyes, which are sensitive to visible light, can also be degraded via Excited states. Langmuir Hinshelwood kinetics model describes the degradation rate expressions in terms of the disappearance of compounds. The kinetics of the photocatalysis is not only essential to practical applications but also is key aspect for understanding mechanisms of die photocatalysis.", "author_names": [ "Yc Tang", "C Hu", "Yz Wang" ], "corpus_id": 99651979, "doc_id": "99651979", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Recent advances in mechanisms and kinetics of TiO(2) photocatalysis", "venue": "", "year": 2002 }, { "abstract": "The ever increasing world population and the rapid growth of industrialization globally make necessary the development of clean technologies and affordable materials for remediating environmental pollution from petroleum based hydrocarbons and dyes, among others. Advanced photocatalytic materials may provide an excellent solution for environmental cleanup without generating toxic byproducts as they allow for the complete oxidation of the pollutants and their conversion to benign species. In this review, the basic principle of photocatalyst operation and the importance of bandgap engineering are discussed. TiO2 has been the default photocatalyst although it has several shortcomings. Doping of TiO2 with Ce has been explored extensively in the literature as a way to enable visible light activated photocatalysis and enhanced efficiency. Recent advances in the synthesis of Ce modified TiO2 photocatalytic materials along with photocatalytic reaction mechanisms are summarized.", "author_names": [ "Milind Pawar", "Perena Gouma" ], "corpus_id": 180260505, "doc_id": "180260505", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "A Brief Overview of TiO 2 Photocatalyst for Organic Dye Remediation Case Study of Reaction Mechanisms Involved in Ce TiO 2 Photocatalysts System", "venue": "", "year": 2018 }, { "abstract": "Abstract For the last few decades, photocatalysis has attracted as an emerging successful technology for purifying wastewater by dye degradation from households and industries. TiO 2 based photocatalysis has gained wide attention due to its importance in energy source as well as its outstanding involvement in the reduction in environmental problems. Consequently, researchers and scientists are looking for the synthesis of polyaniline TiO 2 based photocatalysts which are widely being used for the degradation of dyes. Lately, the use of polyaniline as photosensitizers has proved that it immensely enhances photodegradation by its excellent photocatalytic activity under both ultraviolet light and natural sunlight irradiation. Considering this most unique performance of Polyaniline TiO 2 based photocatalysis, the present review provides the recent advances and trends in the development of ultraviolet and visible light responsive polyaniline TiO 2 based photocatalysis for their potential application in environmental remediation by dye degradation. Graphic abstract", "author_names": [ "Nirmala Kumari Jangid", "Sapana Jadoun", "Anjali Yadav", "Manish Kumar Srivastava", "Navjeet Kaur" ], "corpus_id": 221050389, "doc_id": "221050389", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Polyaniline TiO2 based photocatalysts for dyes degradation", "venue": "Polymer Bulletin", "year": 2020 }, { "abstract": "Recent advances in synchrotron based x ray spectroscopy enable materials scientists to emanate fingerprints on important materials properties, e.g. electronic, optical, structural, and magnetic properties, in real time and under nearly real world conditions. This characterization in combination with optimized materials synthesis routes and tailored morphological properties could contribute greatly to the advances in solid state electronics and renewable energy technologies. In connection to this, such perspective reflects the current materials research in the space of emerging energy technologies, namely photocatalysis, with a focus on transition metal oxides, mainly on the Fe 2 O 3 and TiO 2 based materials.", "author_names": [ "Yifan Ye", "Mukes Kapilashrami", "Cheng-Hao Chuang", "Yi-sheng Liu", "Per Anders Glans", "Jinghua Guo" ], "corpus_id": 59380839, "doc_id": "59380839", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "X ray spectroscopies studies of the 3d transition metal oxides and applications of photocatalysis", "venue": "", "year": 2017 }, { "abstract": "", "author_names": [ "Jia-Yan Chen", "Dongyuan Zhao" ], "corpus_id": 235525031, "doc_id": "235525031", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Recent advances in TiO 2 based catalysts for N 2 reduction reaction", "venue": "", "year": 2021 }, { "abstract": "The lithium ion battery (LIB) has proven to be a very reliably used system to store electrical energy, for either mobile or stationary applications. Among others, TiO2 based anodes are the most attractive candidates for building safe and durable lithium ion batteries with high energy density. A variety of TiO2 nanostructures has been thoroughly investigated as anodes in LIBs, e.g. nanoparticles, nanorods, nanoneedles, nanowires, and nanotubes discussed either in their pure form or in composites. In this review, we present the recent developments and breakthroughs demonstrated to synthesize safe, high power, and low cost nanostructured titania based anodes. The reader is provided with an in depth review of well oriented TiO2 based nanotubes fabricated by anodic oxidation. Other strategies for modification of TiO2 based anodes with other elements or materials are also highlighted in this report.", "author_names": [ "Mahmoud Madian", "Alexander Eychmuller", "Lars Giebeler" ], "corpus_id": 54215496, "doc_id": "54215496", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Current Advances in TiO 2 Based Nanostructure Electrodes for High Performance Lithium Ion Batteries", "venue": "", "year": 2018 }, { "abstract": "Photocatalysis is a multifunctional phenomenon that can be employed for energy applications such as H2 production, CO2 reduction into fuels, and environmental applications such as pollutant degradations, antibacterial disinfection, etc. In this direction, it is not an exaggerated fact that TiO2 is blooming in the field of photocatalysis, which is largely explored for various photocatalytic applications. The deeper understanding of TiO2 photocatalysis has led to the design of new photocatalytic materials with multiple functionalities. Accordingly, this paper exclusively reviews the recent developments in the modification of TiO2 photocatalyst towards the understanding of its photocatalytic mechanisms. These modifications generally involve the physical and chemical changes in TiO2 such as anisotropic structuring and integration with other metal oxides, plasmonic materials, carbon based materials, etc. Such modifications essentially lead to the changes in the energy structure of TiO2 that largely boosts up the photocatalytic process via enhancing the band structure alignments, visible light absorption, carrier separation, and transportation in the system. For instance, the ability to align the band structure in TiO2 makes it suitable for multiple photocatalytic processes such as degradation of various pollutants, H2 production, CO2 conversion, etc. For these reasons, TiO2 can be realized as a prototypical photocatalyst, which paves ways to develop new photocatalytic materials in the field. In this context, this review paper sheds light into the emerging trends in TiO2 in terms of its modifications towards multifunctional photocatalytic applications.", "author_names": [ "Mohan Sakar", "R Mithun Prakash", "Trong-On Do" ], "corpus_id": 203578495, "doc_id": "203578495", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Insights into the TiO 2 Based Photocatalytic Systems and Their Mechanisms", "venue": "", "year": 2019 } ]

[ { "abstract": "We report on a German network project in which the technology and the basic electronic properties of amorphous/crystalline silicon heterojunction solar cells are investigated. In contrast to the approach of Sanyo our focus is on hetero solar cells fabricated on p type substrates without an a Si:H(i) buffer layer. One goal of the project is to transfer the results obtained on single crystalline wafers to inexpensive substrates, such as block cast multicrystalline silicon or edge defined film fed grown silicon. All solar cells investigated here are completely processed at low temperatures <250degC) Simulation studies show that a critical parameter is the defect density at the interface between the amorphous and the crystalline semiconductor both at the front and rear side. The interface state density has to be minimized to obtain maximum open circuit voltages. Using optimised deposition conditions of the amorphous silicon efficiencies larger 17% are obtaind on p type c Si wafers and larger 18% on n type c Si. For large area cells a low temperature screen printing process was developed. On a cell area of 10x10 cm2 an efficiency of 12.9% on block cast multicrystalline silicon is achieved.", "author_names": [ "Horst Windgassen", "Uwe Rau", "Philipp Johannes Rostan", "Jurgen Henze", "Jan Schmidt", "Maximilian Scherff", "Wolfgang R Fahrner", "Dietmar Borchert", "Saioa Tardon", "Rudolf Bruggemann", "Helmut Stiebig", "Manfred Schmidt", "Auf der Reihe" ], "corpus_id": 111937876, "doc_id": "111937876", "n_citations": 5, "n_key_citations": 0, "score": 1, "title": "BASIC ELECTRONIC PROPERTIES AND TECHNOLOGY OF TCO/a Si:H(n)/c Si(p) HETEROSTRUCTURE SOLAR CELLS: A GERMAN NETWORK PROJECT", "venue": "", "year": 2005 }, { "abstract": "Among distinct 2 D materials, Graphene has attained higher potential due to its attractive properties. This material provided a new dimension to nanotechnology and material research. It has a 2D honeycomb structure lattice having a single layer of carbon atoms due to which it is flexible in nature, durable and lighter than any material. It has a wide range of applications starting from the fabrication of products, biological engineering, optical electronics, electrical engineering, and biomedical field. Morden Graphene's research has been directed towards the exploration of electronic properties and their electron transfer properties. This attracts the interest of scientists and engineers to come up with new theories and technologies. Experiments are conducted on Graphene to discover new features suitable for different area of interests. Graphene is among one of the materials which are undergoing intense research due to its fascinating properties from the last 2 3 decades. In this review paper, some basic properties of Graphene are discussed, followed by their respective applications, and then current research in Graphene is explored. Overall this paper gives an overview of Graphene in terms of properties and its applications, especially in the medical sector, which will enlighten future research in the field of material science. KeywordsGraphene, 2D Materials, Applications of Graphene, Protective Coatings.", "author_names": [ "Srajan Gupta" ], "corpus_id": 221368417, "doc_id": "221368417", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Recent development in Graphene technology for multidisciplinary properties and its applications: A Review", "venue": "", "year": 2020 }, { "abstract": "Ordered atomic scale superlattices on a surface hold great interest both for basic science and for potential applications in advanced technology. However, controlled fabrication of superlattices down to the atomic scale has proven exceptionally challenging. Here we develop a segregation method to realize self organization of S superlattices at the interface of graphene and S rich Cu substrates. Via scanning tunneling microscope measurements, we directly image well ordered identical nanocluster superlattices and atomic superlattices under the cover of graphene. Scanning tunneling spectra show that the superlattices in turn could modulate the electronic structure of top layer graphene. Importantly, a special ordered S monatomic superlattice commensurate with a graphene lattice is found to drive semimetal graphene into a symmetry broken phase the electronic Kekule distortion phase which opens a bandgap of ~245 meV.", "author_names": [ "Dongling Ma", "Zhong-Qiu Fu", "Xuelei Sui", "Ke-ke Bai", "Jiabin Qiao", "Chao Yan", "Yuanwei Zhang", "Jingyi Hu", "Qian Xiao", "Xinrui Mao", "Wenhui Duan", "Lin He" ], "corpus_id": 206722480, "doc_id": "206722480", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Modulating the Electronic Properties of Graphene by Self Organized Sulfur Identical Nanoclusters and Atomic Superlattices Confined at an Interface.", "venue": "ACS nano", "year": 2018 }, { "abstract": "Signal oscillators based on DDS (Direct Digital Synthesis) are widely used in recent years. However, order metrological characteristics of signals generated by these oscillators have not been studied in many cases, and uses of such oscillators are not always justified. First of all, signals of the most popular sine waveform are unsatisfactory in terms of metrology, including errors of amplitude, period and their instability, total harmonic distortion. Certainly, with the development of integrated circuit fabrication technology, errors of basic units decrease. Therefore, it can be expected that instrumental errors will be decreasing in the nearest future. However, not only instrumental but also method errors are intrinsic to direct digital synthesis of signals. These method errors will determine limiting metrological characteristics as a hardware component of digital oscillators continue to be improved. When considering metrological characteristics of DDS based digital oscillators, it is necessary to take into account that their output signals are quasiperiodic. This produces a complex spectrum of signals. Three methods for estimating a spectrum are proposed. Summation of amplitudes of spectral components in modulus is found to determine the level of signal amplitude and its instability, while vector summation determines period and its instability. Finally, root mean square summation determines total harmonic distortion. This paper analyzes limiting distortions of an output sine wave signal with the aim of identifying the most appropriate application of these oscillators. It should be noted that the method error in this case is a theoretical error, which is very difficult to determine experimentally against other errors. Therefore, only results of mathematical modeling are given in the article. We present the graphics that allow right sampling frequency to be chosen depending on a specified error of amplitude, error of period, and total harmonic distortion of output voltage.", "author_names": [ "Yuriy Konstantinovich Rybin", "T A Petlina" ], "corpus_id": 114481674, "doc_id": "114481674", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Basic metrological properties of electronic oscillators with direct digital synthesis", "venue": "", "year": 2017 }, { "abstract": "The public defense on 12th June 2020 at 12:00 will be available via remote technology. Link: https:/aalto.zoom.us/j/62968943922 Zoom Quick Guide: https:/www.aalto.fi/en/services/zoom quick guide Electronic online display version of the doctoral thesis is available by email by request from aaltodoc [email protected]", "author_names": [ "Miia Kivio" ], "corpus_id": 226736986, "doc_id": "226736986", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Utilization of Ti containing microparticles on improved steel properties Basic studies on inclusions control and interfacial phenomena", "venue": "", "year": 2020 }, { "abstract": "Multifunctional materials having simultaneous electrical and magnetic assembling have been attempted by numerous researchers for next generation electronic appliances. Among such materials, rare earth metals containing double perovskites, such as La2BB'O6 (B Ni, B' Mn) are the utmost studied materials. In this review, we have summarized various physicochemical aspects of La2NiMnO6 such as crystal structure, electrical, magnetic, and magneto transport behavior from earlier studies under several experimental conditions. Magnetic field and temperature effects on magnetoelectric and electronic behavior of this material are described. We discuss how the morphology in the form of bulk phase, thin layer, and nanoparticles affect such physicochemical properties of this material. We also highlighted the role of cation order disorder at 'B' sites and the probability of the resulting numerous electronic behavior in this type of material and expectation on basic understanding of Ni O Mn electronic, as well as magnetic properties. The prospective applications of this material over conventional substances in solar cells, electric tunable devices, biomolecular and gas sensing technologies are also ascribed. The motivation of the present review is to sum up all such behaviors of La2NiMnO6 to find its possible applications in new areas of material research and the directions of future works. La2NiMnO6 double perovskite exhibits simultaneous electric and magnetic orderings Crystal structure, magneto electric, and transport nature affect the functionality of La2NiMnO6 Bulk phase, thin layer, and nanoparticles morphology affect the physical property of La2NiMnO6 La2NiMnO6 holds solar cell, electric tunable device, biomolecular and gas sensing applications La2NiMnO6 double perovskite exhibits simultaneous electric and magnetic orderings Crystal structure, magneto electric, and transport nature affect the functionality of La2NiMnO6 Bulk phase, thin layer, and nanoparticles morphology affect the physical property of La2NiMnO6 La2NiMnO6 holds solar cell, electric tunable device, biomolecular and gas sensing applications", "author_names": [ "Aslam Hossain", "A K M Atique Ullah", "Partha Sarathi Guin", "Sanjay Dhar Roy" ], "corpus_id": 198358340, "doc_id": "198358340", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "An overview of La2NiMnO6 double perovskites: synthesis, structure, properties, and applications", "venue": "Journal of Sol Gel Science and Technology", "year": 2019 }, { "abstract": "Abstract Instrument current and voltage transformers remain the basic apparatuses used in energy measurements in electrical grid. The increasing importance of distributed energy sources necessitates more accurate measurements of consumed as well as generated electrical energy. Both types occur in low voltage network where the main focus is on current transformers (CTs) for electronic type electrical energy meters. These current transformers should fulfil many requirements for precise electrical energy measurements. This paper presents a modern measurement system for various metrological research of CTs offered as 1 and 3 phase current transformers modules (CTMs)", "author_names": [ "Wojciech A Pluta", "Cezary Swieboda", "Jacek Leszczynski", "Marian Soinski" ], "corpus_id": 92983698, "doc_id": "92983698", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Some remarks on metrological properties and production technology of current transformers made of nanocrystalline cores", "venue": "", "year": 2017 }, { "abstract": "Blockchain has been said to be one of the technologies for the future, and researchers have argued that this technology is going to disrupt many industries in the coming years, and democratic elections are one of the key areas blockchain is going to transform. Several organizations have begun experimenting on blockchain enabled e voting platforms, such as Democratic Earth, Horizon State and Follow My Vote. This study seeks to conceptualize a blockchain architecture for the storage of election results that provide trust, transparency, and immutability using distributed ledger technology (DLT) One of the main issues with elections in Ghana and other sub Saharan African countries is the inaccurate recording of votes from polling stations, constituencies and at the national office. There are instances where votes recorded at the polling station changes at the constituencies either intentionally or accidentally. The study discussed the basic properties of the blockchain, such as distributed ledger, consensus mechanisms and cryptographic hash function, and how it can be used to address the current challenges in vote recording during elections. The study evaluates current blockchain enabled e voting systems and designs a blockchain based vote recording system that provides immutability, trust, and transparency. The proposed design addresses the issues of vote tempering because transactions added to the block are secure with a cryptographic hash function which makes tempering of the votes stored in the blockchain nearly impossible and make it immutable.", "author_names": [ "Samuel Agbesi", "George Asante" ], "corpus_id": 210889232, "doc_id": "210889232", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Electronic Voting Recording System Based on Blockchain Technology", "venue": "2019 12th CMI Conference on Cybersecurity and Privacy (CMI)", "year": 2019 }, { "abstract": "The research of new p conjugated molecules with specific applications has become one of the most interesting topics in the fields of chemical physics and materials science. Thanks to their specific properties, these compounds have become the most promising materials for the optoelectronic device technology such as solar cells. The use of low band gap materials is a viable method for a better harvesting of the solar spectrum and an improved raise of its efficiency. The control of this parameter of these materials is a research issue of ongoing interest. In this work a quantum chemical investigation has been performed to explore the optical and electronic properties of a series of different compounds based on pyridine (MPEP) Different electron side groups were introduced to investigate their effects on the electronic structure. The theoretical knowledge of the HOMO and LUMO energy levels of the components is basic in studying organic solar cells so the HOMO, LUMO and energy Egap of the studied compounds have been calculated and reported. These properties suggest these materials as good candidates for organic solar cells.", "author_names": [ "T Abram", "Rachid Hmamouchi", "Tahar Lakhlifi", "L Bejjit", "M El M Hamidi", "Mohammed Bouachrine" ], "corpus_id": 56240430, "doc_id": "56240430", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Organic materials based on MPEP for photovoltaic devices. Correlation structure/electronic properties", "venue": "", "year": 2014 }, { "abstract": "The research in new pi conjugated molecules with specific applications has become one of the most interesting topics in the fields of chemical physics and materials science. Thanks to their specific properties, these compounds have become the most promising materials for the optoelectronic device technology such as solar cells. The use of low band gap materials is a viable method for a better harvesting of the solar spectrum and an improved raise of its efficiency. The control of this parameter of these materials is a research issue of ongoing interest. In this work a quantum chemical investigation has been performed to explore the optical and electronic properties of a series of different compounds based on antracene and pyrazine. Different electron side groups were introduced to investigate their effects on the electronic structure. The theoretical knowledge of the HOMO and LUMO energy levels of the components is basic in studying organic solar cells so the HOMO, LUMO and energy Egap of the studied compounds have been calculated and reported. These properties suggest these materials as good candidates for organic solar cells.", "author_names": [ "Rachid Hmammouchi", "Azeddine Adad", "Mohammed Bouachrine", "Tahar Lakhlifi" ], "corpus_id": 199384139, "doc_id": "199384139", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Organic materials based on pyrazine for photovoltaic devices Correlation structure electronic properties", "venue": "", "year": 2013 } ]

[ { "abstract": "This paper describes the development and validation of the currently smallest aerial platform with olfaction capabilities. The developed Smelling Nano Aerial Vehicle (SNAV) is based on a lightweight commercial nano quadcopter (27 g) equipped with a custom gas sensing board that can host up to two in situ metal oxide semiconductor (MOX) gas sensors. Due to its small form factor, the SNAV is not a hazard for humans, enabling its use in public areas or inside buildings. It can autonomously carry out gas sensing missions of hazardous environments inaccessible to terrestrial robots and bigger drones, for example searching for victims and hazardous gas leaks inside pockets that form within the wreckage of collapsed buildings in the aftermath of an earthquake or explosion. The first contribution of this work is assessing the impact of the nano propellers on the MOX sensor signals at different distances to a gas source. A second contribution is adapting the 'bout' detection algorithm, proposed by Schmuker et al. (2016) to extract specific features from the derivative of the MOX sensor response, for real time operation. The third and main contribution is the experimental validation of the SNAV for gas source localization (GSL) and mapping in a large indoor environment (160 m2) with a gas source placed in challenging positions for the drone, for example hidden in the ceiling of the room or inside a power outlet box. Two GSL strategies are compared, one based on the instantaneous gas sensor response and the other one based on the bout frequency. From the measurements collected (in motion) along a predefined sweeping path we built (in less than 3 min) a 3D map of the gas distribution and identified the most likely source location. Using the bout frequency yielded on average a higher localization accuracy than using the instantaneous gas sensor response (1.38 m versus 2.05 m error) however accurate tuning of an additional parameter (the noise threshold) is required in the former case. The main conclusion of this paper is that a nano drone has the potential to perform gas sensing tasks in complex environments.", "author_names": [ "Javier Burgues", "Victor Manuel Hernandez Bennetts", "Achim J Lilienthal", "Santiago Marco" ], "corpus_id": 59274176, "doc_id": "59274176", "n_citations": 41, "n_key_citations": 1, "score": 1, "title": "Smelling Nano Aerial Vehicle for Gas Source Localization and Mapping", "venue": "Sensors", "year": 2019 }, { "abstract": "Identification and quantification of trace gas sources is a major challenge for understanding and regulating air quality and greenhouse gas emissions. Current approaches provide either continuous but localized monitoring, or quasi instantaneous \"snapshot in time\" regional monitoring. There is a need for emissions detection that provides both continuous and regional coverage, because sources and sinks can be episodic and spatially variable. We field deploy a dual frequency comb laser spectrometer for the first time, enabling an observing system that provides continuous detection of trace gas sources over multiple square kilometer regions. Field tests simulating methane emissions from oil and gas production demonstrate detection and quantification of a 1.6 g min 1 source (less than the average emissions from a small pneumatic controller) from a distance of 1 km, and the ability to discern two leaks among a field of many potential sources. The technology achieves the goal of detecting, quantifying, and attributing emissions sources continuously through time, over large areas, and at emissions rates ~1000x lower than current regional approaches. It therefore provides a useful tool for monitoring and mitigating undesirable sources and closes a major information gap in the atmospheric sciences.", "author_names": [ "Sean C Coburn", "Caroline B Alden", "Robert J Wright", "Kevin C Cossel", "Esther Baumann", "Gar Wing Truong", "Fabrizio Raphael Giorgetta", "Colm Sweeney", "Nathan R Newbury", "K Rajendra Prasad", "Ian Coddington", "Gregory B Rieker" ], "corpus_id": 134129396, "doc_id": "134129396", "n_citations": 91, "n_key_citations": 1, "score": 0, "title": "Regional trace gas source attribution using a field deployed dual frequency comb spectrometer", "venue": "", "year": 2018 }, { "abstract": "This paper addresses the localization of a gas emission source within a real world human environment with a mobile robot. Our approach is based on an efficient and coherent system that fuses different sensor modalities (i.e. vision and chemical sensing) to exploit, for the first time, the semantic relationships among the detected gases and the objects visually recognized in the environment. This novel approach allows the robot to focus the search on a finite set of potential gas source candidates (dynamically updated as the robot operates) while accounting for the non negligible uncertainties in the object recognition and gas classification tasks involved in the process. This approach is particularly interesting for structured indoor environments containing multiple obstacles and objects, enabling the inference of the relations between objects and between objects and gases. A probabilistic Bayesian framework is proposed to handle all these uncertainties and semantic relations, providing an ordered list of candidates to be the source. This candidate list is updated dynamically upon new sensor measurements to account for objects not previously considered in the search process. The exploitation of such probabilities together with information such as the locations of the objects, or the time needed to validate whether a given candidate is truly releasing gases, is delegated to a path planning algorithm based on Markov decision processes to minimize the search time. The system was tested in an office like scenario, both with simulated and real experiments, to enable the comparison of different path planning strategies and to validate its efficiency under real world conditions.", "author_names": [ "Javier Gonzalez Monroy", "Jose-Raul Ruiz-Sarmiento", "Francisco Angel Moreno", "Francisco Melendez-Fernandez", "Cipriano Galindo", "Javier Gonzalez" ], "corpus_id": 54123323, "doc_id": "54123323", "n_citations": 29, "n_key_citations": 0, "score": 0, "title": "A Semantic Based Gas Source Localization with a Mobile Robot Combining Vision and Chemical Sensing", "venue": "Sensors", "year": 2018 }, { "abstract": "The design of a flying odor compass is proposed for the localization of gas source. The compass is built on a quad rotor helicopter and contains three gas sensors. A data processing method is proposed to estimate the direction which the odor comes from. The method adopts continuous wavelet transform and modulus maxima approaches to uncover the time difference information hidden in the gas sensor signals. Experiments have demonstrated the effectiveness of this design.", "author_names": [ "Bing Luo", "Jia-Ying Wang", "Ming Zeng" ], "corpus_id": 28976406, "doc_id": "28976406", "n_citations": 11, "n_key_citations": 3, "score": 0, "title": "A Flying Odor Compass to Autonomously Locate the Gas Source", "venue": "IEEE Transactions on Instrumentation and Measurement", "year": 2018 }, { "abstract": "The occurrence of anaerobic oxidation of methane (AOM) and trace methane oxidation (TMO) was investigated in a freshwater natural gas source. Sediment samples were taken and analyzed for potential electron acceptors coupled to AOM. Long term incubations with 13C labeled CH4 (13CH4) and different electron acceptors showed that both AOM and TMO occurred. In most conditions, 13C labeled CO2 (13CO2) simultaneously increased with methane formation, which is typical for TMO. In the presence of nitrate, neither methane formation nor methane oxidation occurred. Net AOM was measured only with sulfate as electron acceptor. Here, sulfide production occurred simultaneously with 13CO2 production and no methanogenesis occurred, excluding TMO as a possible source for 13CO2 production from 13CH4. Archaeal 16S rRNA gene analysis showed the highest presence of ANME 2a/b (ANaerobic MEthane oxidizing archaea) and AAA (AOM Associated Archaea) sequences in the incubations with methane and sulfate as compared with only methane addition. Higher abundance of ANME 2a/b in incubations with methane and sulfate as compared with only sulfate addition was shown by qPCR analysis. Bacterial 16S rRNA gene analysis showed the presence of sulfate reducing bacteria belonging to SEEP SRB1. This is the first report that explicitly shows that AOM is associated with sulfate reduction in an enrichment culture of ANME 2a/b and AAA methanotrophs and SEEP SRB1 sulfate reducers from a low saline environment.", "author_names": [ "Peer H A Timmers", "Diego A Suarez-Zuluaga", "Minke van Rossem", "Martijn Diender", "A J M Stams", "Caroline M Plugge" ], "corpus_id": 1671923, "doc_id": "1671923", "n_citations": 69, "n_key_citations": 9, "score": 0, "title": "Anaerobic oxidation of methane associated with sulfate reduction in a natural freshwater gas source", "venue": "The ISME Journal", "year": 2016 }, { "abstract": "Abstract The molecular composition, stable carbon and hydrogen isotopes and light hydrocarbons of the Upper Paleozoic tight gas in the Daniudi gas field in the Ordos Basin were investigated to study the geochemical characteristics. Tight gas in the Daniudi gas field displays a dryness coefficient (C1/C1 5) of 0.845 0.977 with generally positive carbon and hydrogen isotopic series, and the C7 and C5 7 light hydrocarbons of tight gas are dominated by methylcyclohexane and iso alkanes, respectively. The identification of gas origin and gas source correlation indicate that tight gas is coal type gas, and the gases reservoired in the Lower Permian Shanxi Fm. (P1s) and Lower Shihezi Fm. (P1x) had a good affinity and were derived from the P1s coal measure source rocks, whereas the gas reservoired in the Upper Carboniferous Taiyuan Fm. (C3t) was derived from the C3t coal measure source rocks. The molecular and methane carbon isotopic fractionations of natural gas support that the P1x gas was derived from the P1s source rocks. The differences of geochemical characteristics of the C3t gas from different areas in the field suggest the effect of maturity difference of the source rocks rather than the diffusive migration, and the large scale lateral migration of the C3t gas seems unlikely. Comparative study indicates that the differences of the geochemical characteristics of the P1s gases from the Yulin and Daniudi gas fields originated likely from the maturity difference of the in situ source rocks, rather than the effect of large scale lateral migration of the P1s gases.", "author_names": [ "Xiaoqi Wu", "Quanyou Liu", "Jianhui Zhu", "Kuang Li", "Guangxiang Liu", "Yingbin Chen", "Chunhua Ni" ], "corpus_id": 133283878, "doc_id": "133283878", "n_citations": 33, "n_key_citations": 0, "score": 0, "title": "Geochemical characteristics of tight gas and gas source correlation in the Daniudi gas field, the Ordos Basin, China", "venue": "", "year": 2017 }, { "abstract": "Mobile robot olfaction systems combine gas sensors with mobility provided by robots. They relief humans of dull, dirty and dangerous tasks in applications such as search rescue or environmental monitoring. We address gas source localization and especially the problem of minimizing exploration time of the robot, which is a key issue due to energy constraints. We propose an active search approach for robots equipped with MOX gas sensors and an anemometer, given an occupancy map. Events of rapid change in the MOX sensor signal \"bouts\" are used to estimate the distance to a gas source. The wind direction guides a Gaussian regression, which interpolates distance estimates. The contributions of this paper are two fold. First, we extend previous work on gas source distance estimation with MOX sensors and propose a modification to cope better with turbulent conditions. Second, we introduce a novel active search gas source localization algorithm and validate it in a real world environment.", "author_names": [ "Mikel Vuka", "Erik Schaffernicht", "Michael Schmuker", "Victor Manuel Hernandez Bennetts", "Francesco Amigoni", "Achim J Lilienthal" ], "corpus_id": 3014620, "doc_id": "3014620", "n_citations": 13, "n_key_citations": 1, "score": 0, "title": "Exploration and localization of a gas source with MOX gas sensors on a mobile robot A Gaussian regression bout amplitude approach", "venue": "2017 ISOCS/IEEE International Symposium on Olfaction and Electronic Nose (ISOEN)", "year": 2017 }, { "abstract": "Abstract Estimating the distance of a gas source is important in many applications of chemical sensing, like e.g. environmental monitoring, or chemically guided robot navigation. If an estimation of the gas concentration at the source is available, source proximity can be estimated from the time averaged gas concentration at the sensing site. However, in turbulent environments, where fast concentration fluctuations dominate, comparably long measurements are required to obtain a reliable estimate. A lesser known feature that can be exploited for distance estimation in a turbulent environment lies in the relationship between source proximity and the temporal variance of the local gas concentration the farther the source, the more intermittent are gas encounters. However, exploiting this feature requires measurement of changes in gas concentration on a comparably fast time scale, that have up to now only been achieved using photo ionisation detectors. Here, we demonstrate that by appropriate signal processing, off the shelf metal oxide sensors are capable of extracting rapidly fluctuating features of gas plumes that strongly correlate with source distance. We show that with a straightforward analysis method it is possible to decode events of large, consistent changes in the measured signal, so called 'bouts' The frequency of these bouts predicts the distance of a gas source in wind tunnel experiments with good accuracy. In addition, we found that the variance of bout counts indicates cross wind offset to the centreline of the gas plume. Our results offer an alternative approach to estimating gas source proximity that is largely independent of gas concentration, using off the shelf metal oxide sensors. The analysis method we employ demands very few computational resources and is suitable for low power microcontrollers.", "author_names": [ "Michael Schmuker", "Viktor Bahr", "Ramon Huerta" ], "corpus_id": 14293652, "doc_id": "14293652", "n_citations": 29, "n_key_citations": 5, "score": 0, "title": "Exploiting plume structure to decode gas source distance using metal oxide gas sensors", "venue": "", "year": 2016 }, { "abstract": "Gas source localization (GSL) with mobile robots is a challenging task due to the unpredictable nature of gas dispersion, the limitations of the currents sensing technologies, and the mobility constraints of ground based robots. This work proposes an integral solution for the GSL task, including source declaration. We present a novel pseudo gradient based plume tracking algorithm and a particle filter based source declaration approach, and apply it on a gas sensitive micro drone. We compare the performance of the proposed system in simulations and real world experiments against two commonly used tracking algorithms adapted for aerial exploration missions.", "author_names": [ "Patrick P Neumann", "Victor Manuel Hernandez Bennetts", "Achim J Lilienthal", "Matthias Bartholmai", "Jochen H Schiller" ], "corpus_id": 29973960, "doc_id": "29973960", "n_citations": 134, "n_key_citations": 5, "score": 0, "title": "Gas source localization with a micro drone using bio inspired and particle filter based algorithms", "venue": "Adv. Robotics", "year": 2013 }, { "abstract": "RATIONALE High precision stable isotope measurements in gas source isotope ratio mass spectrometry are generally carried out by repeated comparison of the composition of an unknown sample with that of a working gas (WG) through a dual inlet (DI) Due to the established DI protocols, however, most of the sample gas is wasted rather than measured, which is a major problem when sample size is limited. Here we propose a new methodology allowing the measurement of a much larger portion of the available sample. METHODS We tested a new measurement protocol, the long integration dual inlet (LIDI) method, which consists of a single measurement of the sample for 200 to 600 seconds followed by a single measurement of the WG. The isotope ratios of the sample are calculated by comparison of the beam ratios of the WG and sample at equivalent intensities of the major ion beam. RESULTS Three isotopically very different CO2 samples were analyzed. The LIDI measurements of large samples (50 to 100 umol of CO2) measured at quasi constant beam sizes, and of small samples (1.5 to 2 umol of CO2) measured in micro volume mode, generated results that are indistinguishable from the standard DI measurements for carbon, oxygen and clumped isotope compositions. The external precision of D47 using the LIDI protocol 0.007%0) is similar to that of the state of the art DI measurements. CONCLUSIONS For traditional and clumped isotope measurements of CO2, the LIDI protocol allows the measurement of a much larger portion of the sample gas rather than only ~20% of it. In addition, the sample can be measured at higher signal intensity and for longer time, allowing the measurement of smaller samples while preserving precision. We suggest that other gases commonly used for stable isotope measurements with gas source mass spectrometry would also benefit from this new protocol.", "author_names": [ "Bin Hu", "Jens Radke", "H J Schluter", "Frank Heine", "Liping Zhou", "Stefano Michele Bernasconi" ], "corpus_id": 8798693, "doc_id": "8798693", "n_citations": 38, "n_key_citations": 4, "score": 0, "title": "A modified procedure for gas source isotope ratio mass spectrometry: the long integration dual inlet (LIDI) methodology and implications for clumped isotope measurements.", "venue": "Rapid communications in mass spectrometry RCM", "year": 2014 } ]

[ { "abstract": "Wide bandgap semiconductors show superior material properties enabling potential power device operation at higher temperatures, voltages, and switching speeds than current Si technology. As a result, a new generation of power devices is being developed for power converter applications in which traditional Si power devices show limited operation. The use of these new power semiconductor devices will allow both an important improvement in the performance of existing power converters and the development of new power converters, accounting for an increase in the efficiency of the electric energy transformations and a more rational use of the electric energy. At present, SiC and GaN are the more promising semiconductor materials for these new power devices as a consequence of their outstanding properties, commercial availability of starting material, and maturity of their technological processes. This paper presents a review of recent progresses in the development of SiC and GaN based power semiconductor devices together with an overall view of the state of the art of this new device generation.", "author_names": [ "Jose Millan", "Philippe Godignon", "Xavier Perpina", "Amador Perez-Tomas", "Jose Rebollo" ], "corpus_id": 23719999, "doc_id": "23719999", "n_citations": 1075, "n_key_citations": 33, "score": 1, "title": "A Survey of Wide Bandgap Power Semiconductor Devices", "venue": "IEEE Transactions on Power Electronics", "year": 2014 }, { "abstract": "Abstract Diamond is known as an ultimate material because of its superior properties and it is expected to be employed in next generation power electronic devices. Progress in epitaxial growth and fabrication techniques such as p and n type doping control with low compensation and surface treatment have improved the performance of power devices. High forward current density and long term stability have been achieved for Schottky barrier diodes operating at 400 degC. Fast turn off operation with low loss and a high blocking capability of 10 kV have also been realized. In addition, high blocking voltages of more than 2 kV have been achieved for switching devices such as metal semiconductor field effect transistors (MESFETs) and metal oxide semiconductor FETs. To maximize device performance up to the material limit requires the development of fabrication techniques such as selective area doping, lithography, etching, formation of diamond/oxide interfaces and also defect reduction. Here, the current status of semiconductor diamond technology is reviewed.", "author_names": [ "H Umezawa" ], "corpus_id": 103470776, "doc_id": "103470776", "n_citations": 59, "n_key_citations": 1, "score": 0, "title": "Recent advances in diamond power semiconductor devices", "venue": "", "year": 2018 }, { "abstract": "Modern civilization is related to the increased use of electric energy for industry production, human mobility, and comfortable living. Highly efficient and reliable power electronic systems, which convert and process electric energy from one form to the other, are critical for smart grid and renewable energy systems. The power semiconductor device, as the cornerstone technology in a power electronics system, plays a pivotal role in determining the system efficiency, size, and cost. Starting from the invention and commercialization of silicon bipolar junction transistor 60 years ago, a whole array of silicon power semiconductor devices have been developed and commercialized. These devices enable power electronics systems to reach ultrahigh efficiency and high power capacity needed for various smart grid and renewable energy system applications such as photovoltaic (PV) wind, energy storage, electric vehicle (EV) flexible ac transmission system (FACTS) and high voltage dc (HVDC) transmission. In the last two decades, newer generations of power semiconductor devices based on wide bandgap (WBG) materials, such as SiC and GaN, were developed and commercialized further pushing the boundary of power semiconductor devices to higher voltages, higher frequencies, and higher temperatures. This paper reviews some of the major power semiconductor devices technologies and their potential impacts and roadmaps.", "author_names": [ "Alex Q Huang" ], "corpus_id": 34692580, "doc_id": "34692580", "n_citations": 123, "n_key_citations": 6, "score": 0, "title": "Power Semiconductor Devices for Smart Grid and Renewable Energy Systems", "venue": "Proceedings of the IEEE", "year": 2017 }, { "abstract": "At the heart of modern power electronics converters are power semiconductor switching devices. The emergence of wide bandgap (WBG) semiconductor devices, including silicon carbide and gallium nitride, promises power electronics converters with higher efficiency, smaller size, lighter weight, and lower cost than converters using the established siliconbased devices. However, WBG devices pose new challenges for converter design and require more careful characterization, in particular due to their fast switching speed and more stringent need for protection. Characterization of Wide Bandgap Power Semiconductor Devices presents comprehensive methods with examples for the characterization of this important class of power devices. After an introduction, the book covers pulsed static characterization; junction capacitance characterization; fundamentals of dynamic characterization; gate drive for dynamic characterization; layout design and parasitic management; protection design for double pulse test; measurement and data processing for dynamic characterization; cross talk consideration; impact of three phase system; and topology considerations.", "author_names": [ "Fei Wang", "Zheyu Zhang", "Edward A Jones" ], "corpus_id": 139454903, "doc_id": "139454903", "n_citations": 18, "n_key_citations": 3, "score": 0, "title": "Characterization of Wide Bandgap Power Semiconductor Devices", "venue": "", "year": 2018 }, { "abstract": "Research on high voltage (HV) silicon carbide (SiC) power semiconductor devices has attracted much attention in recent years. This paper overviews the development and status of HV SiC devices. Meanwhile, benefits of HV SiC devices are presented. The technologies and challenges for HV SiC device application in converter design are discussed. The state of the art applications of HV SiC devices are also reviewed.", "author_names": [ "Shiqi Ji", "Zheyu Zhang", "Fred Wang" ], "corpus_id": 115276142, "doc_id": "115276142", "n_citations": 63, "n_key_citations": 4, "score": 0, "title": "Overview of high voltage sic power semiconductor devices: development and application", "venue": "", "year": 2017 }, { "abstract": "The thermal behavior of power electronics devices has been a crucial design consideration, because it is closely related to the reliability and also the cost of the converter system. Unfortunately, the widely used thermal models based on lumps of thermal resistances and capacitances have their limits to correctly predict the device temperatures, especially when considering the thermal grease and heat sink attached to the power semiconductor devices. In this paper, frequency domain approach is applied to the modeling of the thermal dynamics for power devices. The limits of the existing RC lump based thermal networks are explained from a point of view of frequency domain. Based on the discovery, a more advanced thermal model developed in the frequency domain is proposed, which can be easily established by characterizing the slope variation from the bode diagram of the typically used Foster thermal network. The proposed model can be used to predict not only the internal temperature behaviors of the devices but also the behaviors of the heat flowing out of the devices. As a result, more correct estimation of device temperature can be achieved when considering the cooling conditions for the devices.", "author_names": [ "Ke Ma", "Ning He", "Marco Liserre", "Frede Blaabjerg" ], "corpus_id": 23550146, "doc_id": "23550146", "n_citations": 100, "n_key_citations": 7, "score": 0, "title": "Frequency Domain Thermal Modeling and Characterization of Power Semiconductor Devices", "venue": "IEEE Transactions on Power Electronics", "year": 2016 }, { "abstract": "Wire bond lift off and Solder fatigue are degradation mechanisms that dominate the lifetime of power semiconductor packages. Although their lifetime is commonly estimated at the design stage, based on mission profiles and physics of failure models, there are many uncertainties associated with such lifetime estimates, emerging, e.g. from model calibration errors, manufacturing tolerances, etc. These uncertainties, combined with the diverse working environments of power semiconductor packages result in inaccurate lifetime estimates. This paper presents an approach for estimating the extent of degradation in power semiconductor packages based on online monitoring of key parameters of the semiconductor, namely, the thermal resistance <inline formula><tex math notation=\"LaTeX\"$R_{\\rm{thja} /tex math>/inline formula> and the electrical resistance <inline formula><tex math notation=\"LaTeX\"$R_{\\rm{CE} /tex math>/inline formula> Using these two parameters, solder fatigue and wire bond lift off can be detected during normal converter operation. In order to estimate these two parameters, two techniques are introduced: a residual obtained from a Kalman filter, which estimates the change in the thermal resistance <inline formula> <tex math notation=\"LaTeX\"$R_{\\rm{thja}/tex math>/inline formula> and a recursive least squares algorithm, which is used to estimate the electrical resistance. Both methods are implemented online and validated experimentally.", "author_names": [ "Mohd Amir Eleffendi", "C Mark Johnson" ], "corpus_id": 34869451, "doc_id": "34869451", "n_citations": 49, "n_key_citations": 1, "score": 0, "title": "In Service Diagnostics for Wire Bond Lift off and Solder Fatigue of Power Semiconductor Packages", "venue": "IEEE Transactions on Power Electronics", "year": 2017 }, { "abstract": "Low temperature Ag sintering provides a lead free die attachment method that is compatible with high temperature (300 degC) power electronics applications. The reliability of sintered Ag die attach for Si and SiC die has been studied on both thick film substrates for lower current power applications and direct bond copper (DBC) substrates for higher current power applications. Pressureless and low pressure sintering were evaluated. Sintering with low pressure yielded lower porosity (15 17% versus pressureless sintering ~30% Reliability was evaluated with thermal aging (300 degC) and thermal cycling 55 degC to 300 degC) tests. Reliable Ag sintered die attach was achieved with assemblies having Ag bearing surface finishes on both the die and the substrate. In contrast, the shear strength after 300 degC aging was greatly reduced when Au metallization was used either on the die or on substrate surface. In some cases, low pressure sintering delayed the failure of the sintered Ag die attach to Au surfaces when aged at 300 degC compared to the pressureless sintering. The reliability with Pd containing substrate metallizations was intermediate between Ag and Au metallizations. The thermal cycle reliability on DBC substrates was limited by failure at the Cu to alumina interface over the wide temperature range, while on the thick film substrates high adhesion was maintained after 1000 thermal cycles.", "author_names": [ "Fang Yu", "Jinzi Cui", "Zhangming Zhou", "Kun Fang", "R Wayne Johnson", "Michael C Hamilton" ], "corpus_id": 8478975, "doc_id": "8478975", "n_citations": 64, "n_key_citations": 0, "score": 0, "title": "Reliability of Ag Sintering for Power Semiconductor Die Attach in High Temperature Applications", "venue": "IEEE Transactions on Power Electronics", "year": 2017 }, { "abstract": "The investigation shows that power semiconductor devices are the most fragile components of power electronic systems.Improving the reliability of power devices is the basis of a reliable power electronic system, and in recent years, many studies have focused on power device reliability.This paper describes the current state of the art in reliability research for power semiconductor devices, mainly includes failure mechanisms,condition monitoring, lifetime evaluation and active thermal control.Among them,condition monitoring technology are classified and summarized by the failure mechanism and the change rules of characteristic quantities; The method of lifetime estimation isillustrated from the practical point of view;Methods of active thermal control are classified and summarized from the two ideas of reducing loss and loss compensation which are refined by the principle of realization. At last, this paper draws the existing problems and challenges of power devices reliability studies.", "author_names": [ "Bo Wang", "Jie Cai", "Xiong Du", "Luowei Zhou" ], "corpus_id": 54667815, "doc_id": "54667815", "n_citations": 37, "n_key_citations": 0, "score": 0, "title": "Review of power semiconductor device reliability for power converters", "venue": "", "year": 2017 }, { "abstract": "Bulk gallium nitride (GaN) power semiconductor devices are gaining significant interest in recent years, creating the need for technology computer aided design (TCAD) simulation to accurately model and optimize these devices. This paper comprehensively reviews and compares different GaN physical models and model parameters in the literature, and discusses the appropriate selection of these models and parameters for TCAD simulation. 2 D drift diffusion semi classical simulation is carried out for 2.6 kV and 3.7 kV bulk GaN vertical PN diodes. The simulated forward current voltage and reverse breakdown characteristics are in good agreement with the measurement data even over a wide temperature range.", "author_names": [ "Gourab Sabui", "Peter J Parbrook", "Miryam Arredondo-Arechavala", "Z John Shen" ], "corpus_id": 55278684, "doc_id": "55278684", "n_citations": 32, "n_key_citations": 0, "score": 0, "title": "Modeling and simulation of bulk gallium nitride power semiconductor devices", "venue": "", "year": 2016 } ]

[ { "abstract": "Preface to the Second Edition. Preface to the First Edition. 1 Ray Optics. 2 Wave Optics. 3 Beam Optics. 4 Fourier Optics. 5 Electromagnetic Optics. 6 Ploarization Optics. 7 Photonic Crystal Optics. 8 Guided Wave Optics. 9 Fiber Optics. 10 Resonator Optics. 11 Statistical Optics. 12 Photon Optics. 13 Photon and Atoms. 14 Laser Amplifiers. 15 Lasers. 16 Semiconductor Optics. 17 Semiconductor Photon Sources. 18 Semiconductor Photon Detectors. 19 Acousto Optics. 20 Electro Optics. 21 Nonlinear Optics. 22 Ultrafast Optics. 23 Optical Interconnects and Switches. 24 Optical Fiber Communications. A Fourier Transform. B Linear Systems. C Modes of Linear Systems. Symbols and Units. Authors. Index.", "author_names": [ "Bahaa E A Saleh", "Malvin Carl Teich", "Richard E Slusher" ], "corpus_id": 120755349, "doc_id": "120755349", "n_citations": 3903, "n_key_citations": 292, "score": 2, "title": "Fundamentals of Photonics", "venue": "", "year": 1991 }, { "abstract": "Thank you very much for downloading fundamentals of photonics. As you may know, people have look numerous times for their chosen books like this fundamentals of photonics, but end up in harmful downloads. Rather than enjoying a good book with a cup of tea in the afternoon, instead they are facing with some malicious bugs inside their desktop computer. fundamentals of photonics is available in our book collection an online access to it is set as public so you can get it instantly. Our books collection saves in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the fundamentals of photonics is universally compatible with any devices to read.", "author_names": [ "Nadine Gottschalk" ], "corpus_id": 63468635, "doc_id": "63468635", "n_citations": 772, "n_key_citations": 59, "score": 0, "title": "Fundamentals Of Photonics", "venue": "", "year": 2016 }, { "abstract": "Although the study of light began in ancient Greece in 500 BC, very few new contributions were proposed until Galileo (born in 1564) Willebrord Snell van Royen and Descartes (born in 1621) independently discovered the law of refraction. A remarkable development from this simple law was carried out by Pierre Fermat in 1657, which gave an alternative point of view to the phenomenon of refraction. In the same year that Galileo died (1642) Newton was born. This started a remarkably creative period in history of science. Newton did not have a particularly clear view about the nature of light. He believed that light was corpuscular in nature and that the particles traveled from the object to the eye as a stream of projectiles. These ideas reduced light propagation to processes of reflection and refraction of light to a collision problem [1] Christian Huygens (in 1690) considered light to be a form of wave that travels from the source to the observer. His theory explained the reflection and refraction phenomena of light. It was then that the controversy between the wave and particle theories of light started. Newton recognized the difficulties in reconciling experimental data with some kind of corpuscular properties. He and some others anyway continued to believe in the corpuscular nature of light up to his death in 1727. Since then, other researchers such as Euler, Young, Fresnel, and Huygens suggested light as a wave in motion and developed a theory that explained the phenomena of optical interference and diffraction (late eighteenth and early nineteenth centuries) CONTENTS", "author_names": [ "B Culshaw", "Jose Miguel Lopez-Higuera" ], "corpus_id": 123681748, "doc_id": "123681748", "n_citations": 290, "n_key_citations": 48, "score": 0, "title": "Fundamentals of Photonics", "venue": "", "year": 2012 }, { "abstract": "Covers modern photonics accessibly and discusses the basic physical principles underlying all the applications and technology of photonics. This volume covers the basic physical principles underlying the technology and all applications of photonics from statistical optics to quantum optics. The topics discussed in this volume are: Photons in perspective; Coherence and Statistical Optics; Complex Light and Singular Optics; Electrodynamics of Dielectric Media; Fast and slow Light; Holography; Multiphoton Processes; Optical Angular Momentum; Optical Forces, Trapping and Manipulation; Polarization States; Quantum Electrodynamics; Quantum Information and Computing; Quantum Optics; Resonance Energy Transfer; Surface Optics; Ultrafast Pulse Phenomena.", "author_names": [ "David L Andrews" ], "corpus_id": 123844894, "doc_id": "123844894", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Photonics, Volume 1: Fundamentals of Photonics and Physics", "venue": "", "year": 2015 }, { "abstract": "This PDF file contains the editorial \"Fundamentals of Photonics, Second Edition\" for JBO Vol. 13 Issue 04", "author_names": [ "Bahaa E A Saleh", "Malvin Carl Teich" ], "corpus_id": 13718118, "doc_id": "13718118", "n_citations": 82, "n_key_citations": 7, "score": 0, "title": "Fundamentals of Photonics, Second Edition", "venue": "", "year": 2007 }, { "abstract": "", "author_names": [ "Erik W Stijns", "Hugo Thienpont" ], "corpus_id": 135957218, "doc_id": "135957218", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Fundamentals of Photonics", "venue": "", "year": 2011 }, { "abstract": "", "author_names": [ "" ], "corpus_id": 162134844, "doc_id": "162134844", "n_citations": 30, "n_key_citations": 0, "score": 0, "title": "FUNDAMENTALS OF PHOTONICS by B.E.A Saleh, M.C. Teich`(Wiley, 2nd edition, 2007)", "venue": "", "year": 2009 }, { "abstract": "", "author_names": [ "Chandrasekhar Roychoudhuri" ], "corpus_id": 138872097, "doc_id": "138872097", "n_citations": 14, "n_key_citations": 1, "score": 0, "title": "Fundamentals of Photonics", "venue": "", "year": 2008 }, { "abstract": "", "author_names": [ "William T Silfvast" ], "corpus_id": 9458436, "doc_id": "9458436", "n_citations": 33, "n_key_citations": 1, "score": 0, "title": "Fundamentals of Photonics Course 1 of 8 Now under field test", "venue": "", "year": 2003 }, { "abstract": "", "author_names": [ "James Dewey Watson" ], "corpus_id": 118799424, "doc_id": "118799424", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Fundamentals of photonics", "venue": "", "year": 1992 } ]

[ { "abstract": "Abstract In this work, we report a simple, low cost, facile fabrication of a SnSe2 based high mobility Metal Insulator Semiconductor Field effect transistor (MISFET) using an unconventional Mott insulator NiO as gate dielectric for an all paper based multifunctional photoswitch and temperature sensor. A single step hydrothermal method yielded SnSe2 on cellulose paper while NiO nanofibers, synthesized using Electrospinning technique was used as gate dielectric. Cu metal tape was used as source, drain and gate contacts while NiO and SnSe2 were used as insulator and semiconductor respectively to fabricate the MISFET. Detailed characterization studies revealed the formation of SnSe2 nanoflakes and NiO nanofibers. The transfer characteristics of SnSe2/NiO FET exhibited a transconductance of 3.25 mS and mobility of 20 cm2V 1s 1 with a Ion/Ioff ratio102 which are extraordinary considering the simplicity of the cleanroom free fabrication technique adopted. The SnSe2/NiO based FET was used as a NIR photo switch and a flexible temperature sensor. The flexible SnSe2 based NIR photoswitch demonstrated a responsivity of 28 mA/cm2, detectivity of 5.25 x 106 jones. The FET based temperature sensor exhibited a TCR value of 4.3 x 10 3 degC 1, better than many commercially available temperature sensors. The higher responsivity can be attributed the effective photo generated carriers and the higher TCR can be imputed to the thermally excited electrons of uniformly grown hexagonal SnSe2 nanoflakes. The fabrication technique of a paper based FET outlined here is a step ahead in developing 2D materials based low cost, flexible multifunctional electronic devices.", "author_names": [ "Sushmitha Veeralingam", "Sushmee Badhulika" ], "corpus_id": 204128411, "doc_id": "204128411", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "2D SnSe2 nanoflakes on paper with 1D NiO gate insulator based MISFET as multifunctional NIR photo switch and flexible temperature sensor", "venue": "", "year": 2020 }, { "abstract": "Textiles enhanced with thin film flexible sensors are well suited for unobtrusive monitoring of skin parameters due to the sensors' high conformability. These sensors can be damaged if they are attached to the surface of the textile, also affecting the textiles' aesthetics and feel. We investigate the effect of embedding flexible temperature sensors within textile yarns, which adds a layer of protection to the sensor. Industrial yarn manufacturing techniques including knit braiding, braiding, and double covering were utilised to identify an appropriate incorporation technique. The thermal time constants recorded by all three sensing yarns was <10 s. Simultaneously, effective sensitivity only decreased by a maximum of 14% compared to the uncovered sensor. This is due to the sensor being positioned within the yarn instead of being in direct contact with the measured surface. These sensor yarns were not affected by bending and produced repeatable measurements. The double covering method was observed to have the least impact on the sensors' performance due to the yarn's smaller dimensions. Finally, a sensing yarn was incorporated in an armband and used to measure changes in skin temperature. The demonstrated textile integration techniques for flexible sensors using industrial yarn manufacturing processes enable large scale smart textile fabrication.", "author_names": [ "Pasindu Lugoda", "Julio C Costa", "Carlos Oliveira", "Leonardo Azael Garcia-Garcia", "Sanjula D Wickramasinghe", "Arash Pouryazdan", "Daniel Roggen", "Tilak Dias", "Niko Munzenrieder" ], "corpus_id": 209490611, "doc_id": "209490611", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Flexible Temperature Sensor Integration into E Textiles Using Different Industrial Yarn Fabrication Processes", "venue": "Sensors", "year": 2020 }, { "abstract": "Disposable temperature sensors have great advantages in public health security and infectious disease control. However, complicated fabrication processes and poor performances persistently restrict their practical applications. In this paper, a flexible temperature sensor is firstly developed by directly writing or mask spraying commonly used paper with a highly thermo sensitive graphene nanoribbon (GNR) ink. The inexpensive, green materials and process endow the GNR sensors with the properties of being low cost, degradable and pollution free. The band gap and the local traps of GNRs, caused by the nanoscale effect and oxygen doping, make the sensor highly thermo sensitive. The sensor also shows fast response, precise resolution and good bendable properties. As demonstrated, the sensor achieves monitoring of respiratory rate, measurement of body temperature, identification of human touch and constituting a 5 x 5 array for temperature mapping. These results demonstrate that the GNRs sensor is highly promising as an economical disposable device for personal healthcare and disease monitoring.", "author_names": [ "Xue Gong", "Longjun Zhang", "Yinan Huang", "Shuguang Wang", "Gebo Pan", "Liqiang Li" ], "corpus_id": 225735777, "doc_id": "225735777", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Directly writing flexible temperature sensor with graphene nanoribbons for disposable healthcare devices", "venue": "", "year": 2020 }, { "abstract": "Temperature sensors with good mechanical flexibility, high sensitivity, fast response and recovery time are essential features for real time measurements by electronic Skin (eSkin) This paper presents the fabrication and characterization of a flexible temperature sensor using PEDOT: PSS and carbon nanotube (CNT) at 1:1 mixing ratio. In order to establish the performance enhancement capability of this composition, a comparative study was carried out. This was done by fabricating two flexible temperature sensors each on \\sim 175 \\mu \\mathrm{m} thick PVC substrate using only CNT and then with CNT/PEDOT: PSS polymer composite following simple drop casting technique. Both sensors show good sensitivity \\sim 0.27$ \\circ}\\mathrm{C} 1} for CNT and \\sim 0.64$ \\circ}\\mathrm{C} 1} for CNT/PEDOT: PSS for temperatures varying from $20^\\circ}\\mathrm{C} to $80^\\circ}\\mathrm{C} Although both the sensors, CNT and CNT/PEDOT: PSS composite revealed fast response and recovery time, the latter shows a higher sensitivity \\sim 0.64$\\circ}\\mathrm{C} 1} Further, a comparison of the sensor made with CNT/PEDOT: PSS with similar works in literature reveals that the presented sensor exhibits relatively faster response \\sim 4.8\\mathrm{s} and recovery \\sim 2.5\\mathrm{s} time. This response enhancement can provide a biomimetic eSkin with unique feature.", "author_names": [ "Oliver Ozioko", "Yogeenth Kumaresan", "Ravinder S Dahiya" ], "corpus_id": 226293723, "doc_id": "226293723", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Carbon Nanotube/PEDOT: PSS Composite based Flexible Temperature Sensor with Enhanced Response and Recovery Time", "venue": "2020 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS)", "year": 2020 }, { "abstract": "In this research, a flexible inkjet printed temperature sensor with in house silver nanoparticles ink is presented and compared with the sensor printed with commercial silver nanoparticles ink. These sensors have an average width of 0.5 0.04 mm in the latter and 0.5 0.03 mm in the former. These serpentine structure sensors were printed on polyethylene terephthalate (PET) substrate by using a Fujifilm Dimatix 2850 printer. The corresponding results indicating resistance have been recorded in the range of 30 100 degC to evaluate the sensor performance. The result of the studies showed that there was a linear relationship between the resistance and temperature for both ink types. The printed sensors developed using the in house ink presented higher sensitivity, 0.1086 /degC, compared to the commercial ink, which was 0.0543 /degC. Therefore, the flexible inkjet printed temperature sensor with the in house silver nanoparticles ink is recommended for the large scale productions and implementations.", "author_names": [ "Qiao Jun Liew", "Hing Wah Lee" ], "corpus_id": 229517922, "doc_id": "229517922", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Inkjet Printed Flexible Temperature Sensor Based on Silver Nanoparticles Ink", "venue": "", "year": 2020 }, { "abstract": "In this study, a flexible film temperature sensor was fabricated by screen printing technology. The temperature sensor was fabricated by firstly printing nano silver conductive ink and sequentially carbon temperature sensitive ink onto a flexible polyethylene terephthalate (PET) substrate. By changing the proportion of nano carbon black in the temperature sensitive ink and the sintering temperature of the nano silver conductive ink, the effects on the conductivity and temperature sensitivity of the flexible film sensor were investigated, and the linearity, hysteresis and stability of the prepared sensor were verified. When the sintering temperature of silver electrode based on PET film was 130 degC, the electrode square resistance was 10.2 mO/ When the ambient temperature varies between 25 and 75 degC, the resistance of the temperature sensor decreases as the amount of nano carbon black added increases. Besides, the flexible temperature sensor shows high linearity and good stability. By virtue of the flexibility, simple preparation process and low cost, this flexible temperature sensor that can be found useful in a certain range of applications, including wearable devices, biomedical devices, smart packaging and smart house.", "author_names": [ "Yue Shi", "Shilin Huang", "Zhicheng Sun", "Weitie Wang", "Ruping Liu" ], "corpus_id": 216375089, "doc_id": "216375089", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Performance Study of Flexible Temperature Sensor Based on Carbon Sensitive Material", "venue": "", "year": 2020 }, { "abstract": "In this research, we developed a mass production method for the preparation of thermosensitive ink composite, followed by deposition of the composite on the flexible substrate via spray coating technology. Firstly, Ag micropattern was designed and deposited on flexible polyimide substrate by high precision screen printing. The Ag interdigital electrodes with controlled spacing are realized by optimization of the sintering temperature, and the thermosensitive ink composed of polydimethylsiloxane (PDMS) mixed with graphite powder and graphene was coated on the surface of the electrodes. Effect of sintering temperature on the microstructure and electrical conductivity of Ag electrode is evaluated, and the sensitivity of the flexible temperature sensor in the large dynamic range of 15 40 degC is investigated. Finally, the sensing characteristics, response time, temperature hysteresis and effect of the spontaneous heating are tested, and the experimental results demonstrated a high performance sensor with a higher sensitivity, a smaller hysteresis, a better linearity and a faster response.", "author_names": [ "Ruping Liu", "Yue Shi", "Zhicheng Sun", "Zhengwang Li" ], "corpus_id": 216365172, "doc_id": "216365172", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Fabrication of Flexible Temperature Sensor Based on Printed Electronics", "venue": "", "year": 2020 }, { "abstract": "Graphene derivatives are promising nanomaterials for the development of various flexible electronic devices. In this work, a flexible temperature sensor based on fluorinated graphene (FG) was developed, using screen printing and drop casting processes. Interdigitated electrodes (IDEs) were fabricated by the deposition of silver (Ag) ink on the polyimide substrate, using the screen printing process, and the FG sensing layer was formed by drop casting of FG suspension on the IDEs. The resistive response of the temperature sensor towards temperatures varying from 10 degC to 80 degC, in steps of 10 degC, was investigated. The fabricated temperature sensor has a short response time 2 s) for different target temperature levels. A linear relationship between the relative resistance change (DR/Rb) and the temperature was observed, with a slope of 0.0013/degC and a correlation coefficient of 0.9964. The overall DR/Rb of the sensor was measured as 8.85% when the temperature changed from 20degC to 80 degC. The average temperature coefficient of resistance (TCR) of the temperature sensor was calculated as 0.132 0.005 /degC for the temperature range of 20 degC to 80 degC.", "author_names": [ "Sajjad Hajian", "Binu Baby Narakathu", "Dinesh Maddipatla", "Simin Masihi", "Masoud Panahi", "Richard G Blair", "B J Bazuin", "Massood Zandi Atashbar" ], "corpus_id": 222097613, "doc_id": "222097613", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Flexible Temperature Sensor based on Fluorinated Graphene", "venue": "2020 IEEE International Conference on Electro Information Technology (EIT)", "year": 2020 }, { "abstract": "Integration of sensors with antennas is becoming popular for compact high performance wireless sensing systems. In this direction, here we present a silver electrodes and Poly(3,4 ethylenedioxythiophene:polystyrene (PEDOT:PSS) based printed temperature sensor on a flexible PVC substrate. The temperature sensor was characterised using a digital multimeter for a temperature range from 25$?C to 90#C. The sensor showed a 70% change in resistance for the tested temperature range. Further, the sensing part was integrated with a Near Field Communication (NFC) tag with the data obtained semi quantitatively by means of the intensity of an Light Emittign Diode (LED) connected with the antenna system. In this case, the antenna works as an energy harvester to power an LED indicator connected in series to the resistive temperature sensor. The intensity of the LED, which varies with the increase of temperature, was measured using a lux meter mobile application. The intensity at 70#C was ~42 lux whereas it decreased down to ~14 lux at room temperature ~25#C) The presented system showed potential use as a smart label in applications requiring temperature monitoring.", "author_names": [ "Mitradip Bhattacharjee", "Pablo Escobedo", "Fatemeh Nikbakhtnasrabadi", "Ravinder S Dahiya" ], "corpus_id": 225722548, "doc_id": "225722548", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Printed Flexible Temperature Sensor with NFC Interface", "venue": "2020 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS)", "year": 2020 }, { "abstract": "This work present the fabrication and characterization of a flexible temperature sensor based on the flake graphite (FG)/carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite. The sensor shows high temperature sensitivity and good linearity. The FG/CNT/PDMS temperature sensitive films are prepared by the screen printing process. Superior printability of the FG/CNT/PDMS inks is demonstrated by means of rheology. Field emission scanning electron microscope investigation reveals an interpenetrating network structures between the FG and CNT. Moreover, thermal gravity analysis illustrates that the FG/CNT/PDMS temperature sensitive films have a better thermal stability than that of PDMS blank control film. The temperature dependent resistance behavior suggests that the temperature coefficient of resistance (TCR) value of the FG/CNT/PDMS films can be manipulated by the mass ratio of FG to CNT. When the mass ratio of FG to CNT is 4:1, the TCR is almost reproducible and maintained at the same level of 0.028 K 1 for repeated thermal cycles. These results indicate that the developed FG/CNT/PDMS composite has potential applications for the flexible temperature sensor.", "author_names": [ "Linhui Wu", "Jun Qian", "Jinhua Peng", "Ke Wang", "Zhangming Liu", "Taolin Ma", "Yihua Zhou", "Gaofeng Wang", "Shuangli Ye" ], "corpus_id": 150172600, "doc_id": "150172600", "n_citations": 24, "n_key_citations": 1, "score": 0, "title": "Screen printed flexible temperature sensor based on FG/CNT/PDMS composite with constant TCR", "venue": "Journal of Materials Science: Materials in Electronics", "year": 2019 } ]

[ { "abstract": "", "author_names": [ "H L Grubin" ], "corpus_id": 19117832, "doc_id": "19117832", "n_citations": 14281, "n_key_citations": 363, "score": 1, "title": "The physics of semiconductor devices", "venue": "IEEE Journal of Quantum Electronics", "year": 1979 }, { "abstract": "Density of States function, g(E) Fermi Dirac Distribution function, f(E) Distribution Function and Fermi Energy Equilibrium Distribution of Electrons and Holes n0 and p0 Equation Intrinsic carrier concentration Fermi level for Intrinsic Semiconductor Extrinsic Semiconductor Position of the Fermi Level of the Extrinsic Semiconductor Non Degenerated Semiconductor Variation of EF with Doping Concentration and with Temperature Compensated Semiconductor Statistics of donors and acceptors Formula to remember Question Bank Solved problems Assignment", "author_names": [ "S M Sze" ], "corpus_id": 171088339, "doc_id": "171088339", "n_citations": 3756, "n_key_citations": 590, "score": 0, "title": "PHYSICS OF SEMICONDUCTOR DEVICES", "venue": "", "year": 2007 }, { "abstract": "", "author_names": [ "S M Sze" ], "corpus_id": 222383291, "doc_id": "222383291", "n_citations": 15395, "n_key_citations": 25, "score": 1, "title": "Physics of semiconductor devices", "venue": "", "year": 1969 }, { "abstract": "", "author_names": [ "Simon M Sze", "Kwok K Ng" ], "corpus_id": 123539693, "doc_id": "123539693", "n_citations": 3419, "n_key_citations": 27, "score": 0, "title": "Physics of Semiconductor Devices: Sze/Physics", "venue": "", "year": 2006 }, { "abstract": "", "author_names": [ "S M Sze" ], "corpus_id": 135663396, "doc_id": "135663396", "n_citations": 1876, "n_key_citations": 68, "score": 0, "title": "Physics of semiconductor devices /2nd edition/", "venue": "", "year": 1981 }, { "abstract": "S M Sze 1981 Chichester: John Wiley xii 868 pp price PS28 The first edition of this book has become a 'standard' indeed it is often treated as the 'Bible' on the subject. The second edition is timely because the earlier volume has been overtaken by events in the fast growing world of microelectronic and optoelectronic devices.", "author_names": [ "Peter James Dobson" ], "corpus_id": 184697382, "doc_id": "184697382", "n_citations": 990, "n_key_citations": 89, "score": 0, "title": "Physics of Semiconductor Devices (2nd edn)", "venue": "", "year": 1982 }, { "abstract": "", "author_names": [ "Massimo Rudan" ], "corpus_id": 125424668, "doc_id": "125424668", "n_citations": 33, "n_key_citations": 3, "score": 0, "title": "Physics of Semiconductor Devices, Second Edition", "venue": "", "year": 2018 }, { "abstract": "", "author_names": [ "R K Sharma", "D S Rawal" ], "corpus_id": 126800368, "doc_id": "126800368", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The Physics of Semiconductor Devices", "venue": "", "year": 2019 }, { "abstract": "Preface. Introduction. PART I: SEMICONDUCTOR PHYSICS. Energy Bands and Carrier Concentration in Thermal Equilibrium. Carrier Transport Phenomena. PART II: SEMICONDUCTOR DEVICES. p n Junction. Bipolar Transistor and Related Devices. MOSFET and Related Devices. MESFET and Related Devices. Microwave Diodes, Quantum Effect, and Hot Electron Devices. Photonic Devices. PART III: SEMICONDUCTOR TECHNOLOGY. Crystal Growth and Epitaxy. Film Formation. Lithography and Etching. Impurity Doping. Integrated Devices. Appendix A: List of Symbols. Appendix B: International Systems of Units (SI Units) Appendix C: Unit Prefixes. Appendix D: Greek Alphabet. Appendix E: Physical Constants. Appendix F: Properties of Important Element and Binary Compound Semiconductors at 300 K. Appendix G: Properties of Si and GaAs at 300 K. Appendix H: Derivation of the Density of States in Semiconductor. Appendix I: Derivation of Recombination Rate for Indirect Recombination. Appendix J: Calculation of the Transmission Coefficient for a Symmetric Resonant Tunneling Diode. Appendix K: Basic Kinetic Theory of Gases. Appendix L: Answers to Selected Problems. Index.", "author_names": [ "S M Sze" ], "corpus_id": 93226361, "doc_id": "93226361", "n_citations": 3382, "n_key_citations": 222, "score": 0, "title": "Semiconductor Devices: Physics and Technology", "venue": "", "year": 1985 }, { "abstract": "We present here and in the companion paper (Part II) a general framework for the modeling of semiconductor device variability through the physics based analysis of the small change sensitivity. We consider a very general class of dynamic device operation, i.e. the periodic or quasi periodic large signal (LS) time varying regime, and we evaluate the sensitivity of both dc and harmonic components of the device dynamic working point with respect to process or physical device parameters. The proposed technique is based on the linearization of the physics based device model around a nominal parameter, and extends to the dynamic case the already established Green's function approach to the numerically efficient dc sensitivity analysis. As an example of application, we consider a class A GaAs MESFET microwave power amplifier; the sensitivity of the LS working point with respect to doping and gate work function variations is evaluated through the proposed approach and compared with the result of repeated LS amplifier analyses, showing that the numerically efficient small change sensitivity approach provides reliable predictions for parameter variations up to 10% of the nominal value.", "author_names": [ "Simona Donati Guerrieri", "Fabrizio Bonani", "Francesco Bertazzi", "Giovanni Ghione" ], "corpus_id": 7827082, "doc_id": "7827082", "n_citations": 20, "n_key_citations": 3, "score": 0, "title": "A Unified Approach to the Sensitivity and Variability Physics Based Modeling of Semiconductor Devices Operated in Dynamic Conditions Part I: Large Signal Sensitivity", "venue": "IEEE Transactions on Electron Devices", "year": 2016 } ]

[ { "abstract": "Abstract Generally, pristine semiconductor materials are difficult to own excellent photocatalytic performance, and doping is considered an effective strategy to improve their performance. Herein, Co doped BiOBr (0 1 0) was successfully synthesized. The improved performance could be attributed to the enhanced charge separation efficiency and the expanded light absorption region. Moreover, Co doped BiOBr (0 1 0) owned relatively rough crystal surface with rich atomic defects and large specific surface area, which leaded to its excellent adsorption performance that contributed to the hole dominated degradation process. Through density functional theoretical (DFT) calculation, the effect of Co doping on electronic structure of BiOBr was investigated, indicating that an additional energy level inserted into the band gap of Co doped BiOBr, the band structure of Co doped BiOBr was more intensive than that of BiOBr, and the CBM and VBM of the Co doped BiOBr shifted towards lower energy regions. Tetracycline hydrochloride was chosen to further evaluate the photocatalytic performance of as prepared Co doped BiOBr (0 1 0) and 83% of tetracycline hydrochloride was degrade within 30 min. Finally, the visible light driven catalytic mechanism of Co doped BiOBr (0 1 0) was elucidated. Thus, a feasible strategy was proposed for the fabrication of excellent visible light driven photocatalytic materials.", "author_names": [ "Luhua Shao", "Yutang Liu", "Longlu Wang", "Xinnian Xia", "Xiang-Zhong Shen" ], "corpus_id": 208690585, "doc_id": "208690585", "n_citations": 16, "n_key_citations": 0, "score": 1, "title": "Electronic structure tailoring of BiOBr (0 1 0) nanosheets by cobalt doping for enhanced visible light photocatalytic activity", "venue": "", "year": 2020 }, { "abstract": "Abstract Synergetic experimental and DFT insights of energy band structures and photogenerated rate limiting reactive species are indispensable to design impurity doped photocatalysts for photocatalytic environment remediation and solar fuels. Herein, despite the larger bandgap (Eg) of the Zn doped BiOBr samples, they exhibited superior activity to BiOBr in the photocatalytic water splitting but impaired the photodegradation of Rhodamine B under visible light illumination. Based on the spectral and electrochemical impedance characterisations and DFT simulations, the wider bandgaps of Zn doped BiOBr samples were explicitly assigned to the more positive valence band maxima (VBM) and more negative conduction band minima (CBM) The enhanced photocatalytic water splitting on the Zn doped BiOBr was arisen from the higher redox chemical potentials of charge carriers on respective CBM and VBM, suppressed back reactions and depressed recombination of photogenerated charge carriers. However, the reduced e h+ recombination on the Zn doped BiOBr cannot cancel the detrimental influences from the weaker light absorption and dye sensitisation effects, leading to slower RhB photodegradation.", "author_names": [ "Junqiu Guo", "Xin Liao", "Ming-Hsien Lee", "Geoffrey Hyett", "Chung-Che Huang", "Daniel W Hewak", "Sakellaris Mailis", "Wei Zhou", "Zheng Jiang" ], "corpus_id": 106140758, "doc_id": "106140758", "n_citations": 82, "n_key_citations": 0, "score": 0, "title": "Experimental and DFT insights of the Zn doping effects on the visible light photocatalytic water splitting and dye decomposition over Zn doped BiOBr photocatalysts", "venue": "Applied Catalysis B: Environmental", "year": 2019 }, { "abstract": "Abstract Platinum loaded BiOBr with iodine doping photocatalyst (Pt/I BiOBr) was synthesized to further improve the photocatalytic activity of BiOBr. The photocatalytic test showed the bisphenol A degradation efficiency of Pt/I BiOBr under visible light was about 93% within 20 min, about 5.8, 1.5 and 1.3 times that of BiOBr, iodine doped BiOBr and platinum loaded BiOBr, respectively. The composition, morphology, optical property and dominant active radical were investigated. Based on the results, a possible mechanism was proposed. Iodine doping and platinum loading played a synergetic effect on broadening the visible light absorption range and increasing the photo induced carrier separation efficiency of BiOBr.", "author_names": [ "Tongtong Liu", "Yawen Wang" ], "corpus_id": 213295771, "doc_id": "213295771", "n_citations": 2, "n_key_citations": 0, "score": 1, "title": "Synergistic effect of iodine doping and platinum loading on boosting the visible light photocatalytic activity of BiOBr", "venue": "", "year": 2020 }, { "abstract": "Abstract A novel composite photocatalyst of Bi/BiOBr Bi5+ was successfully developed via a facile two step procedure. The co existence of self doped Bi5+ and in situ deposited Bi(M) was evidenced by X ray diffraction, field emission transmission electron microscope and X ray photoelectron spectra. Its photocatalytic performance on the Rhodamine B (RhB) degradation under visible light irradiation displayed a significant improvement compared with that of Bi/BiOBr or BiOBr Bi5+ which was mainly attributed to the synergistic effect between Bi(M) and Bi5+ For Bi(M) enhancement of visible light absorption capacity was beneficial from surface plasmon resonance (SPR) effect while the promoted separation of photoinduced charge carriers was attributed to the formation of oxygen vacancies (OVs) and Schottky barrier. Besides, Bi(M) induced a predominant exposure of (0 1 0) facet, further enhancing photocatalytic performance. Differently, Bi5+ brought a narrowed bandgap of BiOBr in increasing the carrier density. A plausible mechanism towards RhB degradation was proposed based on analysis of electron transfer pathway and determination of dominant active species. The work offers new routes to enhance the photocatalytic performance of Bi based materials without introducing any impurities.", "author_names": [ "Siqian Chai", "Han-pei Yang", "Zhaoqun Gao", "Ruichen Zhang", "Lina Wang" ], "corpus_id": 224901050, "doc_id": "224901050", "n_citations": 5, "n_key_citations": 1, "score": 1, "title": "Enhancing visible light driven photocatalytic performance of BiOBr by self doping and in situ deposition strategy: A synergistic effect between Bi5+ and metallic Bi", "venue": "", "year": 2020 }, { "abstract": "Abstract Thermostability and band gap deeply influence the photocatalytic activity of the photocatalysts. In this article, BiOBr and La doped BiOBr photocatalysts were synthesized via a solvothermal process. The obtained samples were calcinated at different temperatures. X ray diffraction (XRD) N2 physical adsorption, scanning electron microscopy (SEM) transmission electron microscopy (TEM) thermogravimetry analysis (TGA) and differential thermal analysis (DTA) were utilized to characterize the effect on thermostability after La doping. UV Visible spectroscopy, X ray photoelectron spectroscopy (XPS) photoluminescence (PL) spectroscopy, Electrochemical Impedance Spectroscopy (EIS) transient photocurrent spectroscopy and Mott Schottky (M S) plots were utilized to analyze the band gap and band edge positions of the samples. The results presented that La doping not only enhanced thermostability of BiOBr but also regulated the band gap of heterojunction to advantageous status for promoting the activity. These results could open a new way to tune the heterojunction with rare earth doping by heat treatment.", "author_names": [ "Qizhe Fan", "Xin Chen", "Fanyun Chen", "Jian Tian", "Changling Yu", "Chunfa Liao" ], "corpus_id": 107314542, "doc_id": "107314542", "n_citations": 11, "n_key_citations": 1, "score": 0, "title": "Regulating the stability and bandgap structure of BiOBr during thermo transformation via La doping", "venue": "Applied Surface Science", "year": 2019 }, { "abstract": "", "author_names": [ "Meihua Guan", "Guangmin Ren", "Xiaochao Zhang", "Qirui Zhang", "Changming Zhang", "Rui Li", "Caimei Fan" ], "corpus_id": 229391650, "doc_id": "229391650", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Regulating electronic properties of BiOBr to enhance visible light response via 3d transition metals doping: DFT U calculations", "venue": "", "year": 2020 }, { "abstract": "In this work, Co2+ modification influence on the visible light induced photocatalytic performance of BiOBr was investigated. BiOBr and Co2+ doped BiOBr (Co/BiOBr) nanosheets were fabricated through a facile solvothermal way. The morphology, structure, chemical composition and optical properties of the photocatalysts were characterized by various techniques. The results confirmed the successful synthesis of Co/BiOBr nanosheets and indicated the doped Co2+ had little influence on the surface morphology and crystal structure but expanded the light absorption region. Photoelectrochemical measurements were applied to evaluate the semiconducting properties of Co/BiOBr, and the results implied that compared with the undoped sample, Co/BiOBr had higher charge transfer efficiency and smaller charge transfer resistance which were beneficial to the improvement of visible light driven photocatalytic performance. The as synthesized Co/BiOBr nanosheets exhibited excellent catalytic activity and stability in the photodecomposition of contaminants.", "author_names": [ "Wenmao Huang", "Xin Hua", "Yaping Zhao", "Kai Li", "Liping Tang", "Man Zhou", "Zaisheng Cai" ], "corpus_id": 199176929, "doc_id": "199176929", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Enhancement of visible light driven photocatalytic performance of BiOBr nanosheets by Co2+ doping", "venue": "Journal of Materials Science: Materials in Electronics", "year": 2019 }, { "abstract": "Abstract Ciprofloxacin (CIP) has been a serious threat to the ecological environment and human health due to extensive application and persistence. Low concentrations of CIP can cause toxic effects on the surface and ground waters. It is critical to fabricate accurate and sensitive detection platform of CIP. Herein, a photoelectrochemical detecting platform of CIP has been constructed using metallic Bi self doping BiOBr (Bi/BiOBr) composites. The Bi/BiOBr composites can be synthesized by a facile ethylene glycol (EG) assisted solvothermal method. The metallic Bi nanoparticles can evenly distribute on the surface of BiOBr microspheres. In order to the incorporation of metallic Bi nanoparticles, the Bi/BiOBr composites exhibit excellent photoabsorption property and photoelectric conversion efficiency in visible region. Consequently, the result of photoelectrochemical measurements shows that the photocurrent density of Bi/BiOBr composites is superior to pure BiOBr. The increased photoelectrochemical properties of Bi/BiOBr composites are attributed to the efficient separation of electron hole pairs and rapid electrons transfer. In addition, the photoelectrochemical sensor based on Bi/BiOBr composites has been constructed for sensitively detecting CIP. The photoelectrochemical sensor exhibits a good linear relationship, a low detect limitation and relatively stability for monitoring CIP.", "author_names": [ "Pengcheng Yan", "Li Xu", "Desheng Jiang", "Henan Li", "Jiexiang Xia", "Qi Zhang", "Mingqing Hua", "Huaming Li" ], "corpus_id": 103729277, "doc_id": "103729277", "n_citations": 53, "n_key_citations": 2, "score": 0, "title": "Photoelectrochemical monitoring of ciprofloxacin based on metallic Bi self doping BiOBr nanocomposites", "venue": "", "year": 2018 }, { "abstract": "N/Ti3+ co doping multiphasic TiO2/BiOBr heterojunctions (NT TBx) were prepared by one step in situ hydrothermal processes. The crystal phase, morphology, component, and optical properties of the heterojunctions were characterized by X ray diffraction, scanning electron microscope, transmission electron microscope, X ray photoelectron spectroscopy, and Ultraviolet visible diffuse reflectance spectroscopy techniques, respectively. The as prepared samples exhibit better sonocatalytic activity for the degradation methylene blue, Rhodamine B, and p Nitrophenol aqueous solution compared with pristine TiO2 and N/Ti3+ co doping multiphasic TiO2. Especially, the highest degradation ratio of methylene blue was achieved for NT TB0.3 up to 98.2% after 50 min under ultrasonic irradiation. The high sonocatalytic activity has been kept after four cycles with the tiny decline, indicating the excellent stability of the as prepared samples. The improvement of sonocatalytic activity could be attributed to the formation of doping level and multiphasic TiO2/BiOBr heterojunctions, which account for the absorption of long wavelength light and the electron hole pair separation, respectively. Furthermore, superoxide radical (O2 was demonstrated to be the main reactive species for the degradation of methylene blue under ultrasonic irradiation. This study provides a facile fabrication procedure for N/Ti3+ co doping multiphasic TiO2/BiOBr heterojunctions and demonstrates an efficient route to promote the application of TiO2 in addressing environment related issues.", "author_names": [ "Y Yao", "Mingxuan Sun", "Xiaojiao Yuan", "Yuanhua Zhu", "Xiao-jing Lin", "Sambandam Anandan" ], "corpus_id": 51866523, "doc_id": "51866523", "n_citations": 32, "n_key_citations": 0, "score": 0, "title": "One step hydrothermal synthesis of N/Ti3+ co doping multiphasic TiO2/BiOBr heterojunctions towards enhanced sonocatalytic performance.", "venue": "Ultrasonics sonochemistry", "year": 2018 }, { "abstract": "Abstract Under UV irradiation, self doped Bi 5+ is evidenced to be generated on the surface of BiOBr nanosheets, but with well preserved crystal structure and morphology compared with pure counterpart. Bi 5+ self doping BiOBr (BiOBr 4) exhibits distinct photocatalytic mode for dyes degradation, as compared with pure BiOBr nanosheets. These photodegradation distinctions are mainly due to the simultaneous occurrence of two photoinduced hole (h mediated oxidation processes on the BiOBr surfaces: (1) a portion of photoexcited h participates in the photocatalytic oxidation of dyes, and (2) partial h involves the oxidation of Bi 3+ to Bi 5+ Notably, BiOBr 4 nanosheets comparatively show superior photocatalytic activity for the phenol decomposition as well as the bacterial inactivation. Besides Bi 5+ induced narrowed bandgap and enhanced light adsorption capacity, significantly, the oxidative Bi 5+ acts as electron traps to promote the photoexcited electron hole separation and accelerate h migration, resulting in the considerable photocatalytic enhancement of BiOBr 4 nanosheets. These novel findings will not only give new insights into the photocatalytic mechanism but also explore new route to enhance photocatalytic performance of Bi based materials.", "author_names": [ "Dan Wu", "Songtao Yue", "Wei Wang", "Tiacheng An", "Guiying Li", "Liqun Ye", "Ho Yin Yip", "Po Keung Wong" ], "corpus_id": 99905318, "doc_id": "99905318", "n_citations": 33, "n_key_citations": 0, "score": 0, "title": "Influence of photoinduced Bi related self doping on the photocatalytic activity of BiOBr nanosheets", "venue": "", "year": 2017 } ]

[ { "abstract": "Abstract Internet of Things (IoT) is becoming the new driver for semiconductor industry and the largest electronic market ever seen. The number of IoT nodes is already many times larger than the human population and is continuously growing. It is thus mandatory that IoT nodes become self supplying with energy harvested from environment since periodic exchange of batteries in such a huge number of units (often located in inaccessible places e.g. industrial environment or elements of constructions) is impractical and soon will be simply impossible. Photovoltaic generators may easily harvest energy where light is available, but the IoT nodes often work in dark, hidden locations where the only available energy sources are heat losses. There, ThermoElectric Generators (TEGs) could be the best candidate, if not that if we speak of exploiting heat losses it often means very low temperature differences. This means conditions where TEGs power production drops down dramatically. In this paper we put forward a new idea of TEG's pulse operation that boosts the power production up to X2.7. This extends the domain of applicability of TEGs to lower temperature differences, where conventional TEGs are out of the game. Next, we show that the improvement X2.7 maintains also at larger temperature differences that presents obvious advantages.", "author_names": [ "Maciej Haras", "Michal Markiewicz", "Stephane Monfray", "Thomas Skotnicki" ], "corpus_id": 210803832, "doc_id": "210803832", "n_citations": 3, "n_key_citations": 0, "score": 1, "title": "Pulse mode of operation A new booster of TEG, improving power up to X2.7 to better fit IoT requirements", "venue": "", "year": 2020 }, { "abstract": "The production of high energy photon colliders through Compton back scattering of laser photons was proposed in the early 1980s. Recent developments in high average power short pulse lasers have made such a collider feasible. The Lawrence Livermore Lab has embarked on a multi disciplinary effort to demonstrate a working design of a photon collider. Such a design requires the participation of experts in lasers, optics, accelerators and physics simulation. A laser design, based on the MERCURY architecture, that can provide the necessary laser power is reported along with the design of focusing optics able to be integrated into the confined space of a detector. Having demonstrated the technical feasibility of a photon collider, the expected physics reach of the benchmark /spl gamma//spl gamma/ /spl rarr/ H/sup 0/ mode in our preliminary collider design is reported.", "author_names": [ "Jeffrey Baton Gronberg", "David Asner", "Steven J Boege", "Jason Early", "Kenneth M Skulina", "K A Van Bibber", "Thomas W Markiewicz" ], "corpus_id": 54991180, "doc_id": "54991180", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Lasers and optics for a gamma gamma collider", "venue": "PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268)", "year": 2001 }, { "abstract": "Abstract In recent years, the burst mode caught a lot of attention in the field of ultrashort pulse laser micro machining. One of the major issues is the influence of the burst pulse number and frequency on ablation efficiency and quality. A recent publication reported of a significant increase in ablation efficiency when processing with =25 burst pulses at =100 MHz burst frequencies. This raises the question of whether processing with such high pulse densities can be attributed to non thermal ablation, or whether a quasi nanosecond laser ablation behavior is achieved. To answer this question, we determined ablation efficiencies as function of fluence for silicon, stainless steel, and copper and compared the ablation quality at the optimal fluence using the following laser systems: femtosecond laser operated in single pulse mode, fs laser operated in 28 pulse burst mode with a burst pulse frequency of 148 MHz, and a nanosecond laser with a pulse duration of 175 ns, which is identical with the temporal length of the burst pulse train. The comparison showed that the burst mode used produces similar surface morphologies and melt burrs as the nanosecond laser, but at about 2/3 of its efficiency.", "author_names": [ "Matthias Domke", "Victor V Matylitsky", "Sandra Stroj" ], "corpus_id": 210237686, "doc_id": "210237686", "n_citations": 16, "n_key_citations": 1, "score": 0, "title": "Surface ablation efficiency and quality of fs lasers in single pulse mode, fs lasers in burst mode, and ns lasers", "venue": "", "year": 2020 }, { "abstract": "We demonstrate flat supercontinuum generation in a piece of highly nonlinear fiber pumped with a stable noise like pulse mode locked fiber laser. The compact all fiber laser realizes mode locking based on a nonlinear amplifying loop mirror and emits noise like mode locked pulse with high peak power and high average power. The output pulse has a 3 dB bandwidth of ~35.8 nm with the central wavelength of ~1581 nm. Pumping a 102 m highly nonlinear fiber with the noise like pulse mode locked fiber laser directly, a flat and weak residual pump supercontinuum spanning from ~1370 to ~2200 nm is generated. The spectrum within 1865 to 2200 nm contains more than 45% of the whole energy of the supercontinuum.", "author_names": [ "Xing Luo", "Tong Hoang Tuan", "Than Singh Saini", "Hoa Phuoc Trung Nguyen", "Takenobu Suzuki", "Yasutake Ohishi" ], "corpus_id": 197473717, "doc_id": "197473717", "n_citations": 7, "n_key_citations": 1, "score": 0, "title": "All Fiber Supercontinuum Source Pumped by Noise Like Pulse Mode Locked Laser", "venue": "IEEE Photonics Technology Letters", "year": 2019 }, { "abstract": "This paper considers the operation of a load commutated inverter (LCI) fed synchronous machine when the stator voltage is too low to ensure commutation of the machine side thyristors. Under such low voltage conditions, the LCI is operated in a so called pulse mode, accompanied by higher drive torque harmonics than during standard operation. Following a theoretical analysis, an alternative pulse mode is proposed, describing how to operate the LCI during pulse mode in order to keep the excitation of the natural frequencies of the drive shaft at a minimum.", "author_names": [ "Thomas J Besselmann", "Stefan Almer", "Pieder Jorg" ], "corpus_id": 35913466, "doc_id": "35913466", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Torque Harmonic Minimization for Load Commutated Inverters in Pulse Mode", "venue": "IEEE Transactions on Industrial Electronics", "year": 2018 }, { "abstract": "Taking advantage of the dispersive Fourier transformation technique, the decaying evolution processes of double pulse mode locking in a single walled carbon nanotube based Er doped fiber laser are observed in detail for the first time to our knowledge. The decaying dynamics of the double pulse mode locking state is analyzed in the spectral and temporal domains. We reveal that the two pulses in one cluster disappear either simultaneously or one by one during the decaying processes of double pulse mode locking states. In addition, the spectral evolution patterns of the special double pulse states (i.e. bound states) are extremely distinct at different decline rates of the pump power.", "author_names": [ "Guomei Wang", "G Chen", "Wenlei Li", "Chao Zeng", "Huiran Yang" ], "corpus_id": 125750797, "doc_id": "125750797", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Decaying evolution dynamics of double pulse mode locking", "venue": "", "year": 2018 }, { "abstract": "Abstract The capability to multiplex scintillation detectors or other pulse mode radiation detectors is necessary in some applications where a large number of detectors is required. Frequency domain multiplexing has been previously implemented for applications in astronomy using amplitude modulation on radiation detectors such as transition edge sensors. We propose an alternative method for multiplexing pulse mode radiation detectors in the frequency domain using convolution. We pass the detector signal to a resonator circuit that converts a detector pulse to a damped sinusoid of a specific frequency which gives a unique tag to the detector. We have developed a prototype frequency domain multiplexed system for four EJ 309 organic scintillator detectors using four resonators of unique frequencies. The resonator outputs are combined using a fan in circuit which is then connected to a single digitizer input. Using this system, we demonstrate that the charge collected under the original anode pulse can be estimated from the power spectrum of the damped sinusoid with a relative uncertainty of about 2% The time of arrival of the anode pulse can be estimated using constant fraction discrimination applied to the leading edge of the damped sinusoid with an uncertainty of about 450 ps. We also used a CeBr 3 detector to test the performance of our system for spectroscopic applications and found only small degradation in the resolution for a multiplexed detector.", "author_names": [ "Mudit Mishra", "John K Mattingly", "J M Mueller", "Robert M Kolbas" ], "corpus_id": 115912054, "doc_id": "115912054", "n_citations": 10, "n_key_citations": 1, "score": 0, "title": "Frequency domain multiplexing of pulse mode radiation detectors", "venue": "", "year": 2018 }, { "abstract": "The passive mode locking of vertical external cavity surface emitting lasers (VECSELs) enables the generation of high brightness ultrashort pulses at high repetition rates with unmatched performance. The peak power achievable with sub 200 fs pulse duration is mostly limited by the stability of the fundamental mode locking regime as side pulses or harmonic mode locking emerges at high pump power. Here, we study a colliding pulse mode locked VECSEL generating a pulse duration as short as 128 fs, with an average power of 90 mW per beam and a repetition rate of 3.27 GHz. The relevant laser parameters under different pumping regimes before and after the emergence of a side pulse are then used as input parameters for the simulation of the pulse interactions in the saturable absorber. We present a new comprehensive model for the calculation of saturable losses in the saturable absorber mirror and we study the energy transfer between the two counter propagating pulses. This study reveals how a colliding pulse scheme reduces the saturation fluence of the absorber by a factor 2.9 and suppresses the mode competition between the two counterpropagating pulses of the ring cavity.", "author_names": [ "Alexandre Laurain", "Robert Rockmore", "Hsiu-Ting Chan", "Jorg Hader", "Stephan W Koch", "Antje Ruiz Perez", "Wolfgang Stolz", "Jerome V Moloney" ], "corpus_id": 126143261, "doc_id": "126143261", "n_citations": 17, "n_key_citations": 1, "score": 0, "title": "Pulse interactions in a colliding pulse mode locked vertical external cavity surface emitting laser", "venue": "", "year": 2017 }, { "abstract": "We present a novel racetrack colliding pulse mode locked laser with external pulse picking and optical amplification monolithically integrated on InP. Optical pulses with FWHM of 2.36 ps are observed under hybrid mode locking at 10 GHz repetition rate.", "author_names": [ "Ashish Bhardwaj", "James Ferrara", "Ricardo Bustos Ramirez", "Michael E Plascak", "Gloria Hoefler", "Vikrant Lal", "Fred A Kish", "Peter J Delfyett", "Ming C Wu" ], "corpus_id": 20117711, "doc_id": "20117711", "n_citations": 9, "n_key_citations": 2, "score": 0, "title": "An integrated racetrack colliding pulse mode locked laser with pulse picking modulator", "venue": "2017 Conference on Lasers and Electro Optics (CLEO)", "year": 2017 }, { "abstract": "We report for the first time to the best of our knowledge, an on chip multiple colliding pulse mode locked semiconductor laser source. The device structure is fully integrated, replacing cleaved facet mirrors by using multimode interference reflectors; this allows us to precisely control the location of the saturable absorbers within the cavity length, which is critical to achieve the multiple colliding regime. In this paper, we succeeded to achieve this regime generating a repetition rate at four times the fundamental round trip frequency, demonstrating a repetition rate within the millimeter wave frequency range, at 100 GHz using a 25 GHz resonator cavity length. We also demonstrate the advantage of having the signal on chip including a boost semiconductor optical amplifier in order to increase the output optical power. This novel structure was fabricated on a generic InP photonic integrated technology through a multi project wafer run.", "author_names": [ "Carlos Gordon", "Robinson Cruzoe Guzman", "Vinicio Corral", "Mu-Chieh Lo", "Guillermo Carpintero" ], "corpus_id": 31995868, "doc_id": "31995868", "n_citations": 17, "n_key_citations": 2, "score": 0, "title": "On Chip Multiple Colliding Pulse Mode Locked Semiconductor Laser", "venue": "Journal of Lightwave Technology", "year": 2016 } ]

[ { "abstract": "Unconventional thermo optic responses of CH3NH3PbCl3 enable phase shift compensators and tunable retarders for visible light. Lead halide perovskites are promising semiconductors for high performance photonic devices. Because the refractive index determines the optimal design and performance limit of the semiconductor devices, the refractive index and its change upon external modulations are the most critical properties for advanced photonic applications. Here, we report that the refractive index of halide perovskite CH3NH3PbCl3 shows a distinct decrease with increasing temperature, i.e. a large negative thermo optic coefficient, which is opposite to those of conventional inorganic semiconductors. By using this negative coefficient, we demonstrate the compensation of thermally induced optical phase shifts occurring in conventional semiconductors. Furthermore, we observe a large and slow refractive index change in CH3NH3PbCl3 during photoirradiation and clarify its origin to be a very low thermal conductivity supported by theoretical analysis. The giant thermo optic response of CH3NH3PbCl3 facilitates efficient phase modulation of visible light.", "author_names": [ "Taketo Handa", "Hirokazu Tahara", "Tomoko Aharen", "Yoshihiko Kanemitsu" ], "corpus_id": 198120457, "doc_id": "198120457", "n_citations": 20, "n_key_citations": 0, "score": 0, "title": "Large negative thermo optic coefficients of a lead halide perovskite", "venue": "Science Advances", "year": 2019 }, { "abstract": "Abstract Chalcogenide glasses have attracted much attention for the realization of photonic components owing to their outstanding optical properties in the mid infrared (MIR) region. However, relatively few refractive index dispersion data are presently available for these glasses at MIR wavelengths. This paper presents a mini review of methods we have both used and developed to determine the refractive indices and thermo optic coefficients of chalcogenide glasses at MIR wavelengths, and is supported by new results. The mini review should be useful to both new and established researchers in the chalcogenide glass field and fields of MIR optics, fiber optics and waveguides. Three groups of methods are distinguished: (1) spectroscopic ellipsometry, (2) prism based methods, and (3) methods using Fourier transform infrared (FTIR) transmission data. The mini review is supported by a brief discussion of refractive index models.", "author_names": [ "Y Fang", "David Furniss", "Dinuka Jayasuriya", "Harriet Parnell", "Z Q Tang", "Daniel J Gibson", "Shyam S Bayya", "Jas S Sanghera", "Angela B Seddon", "T M Benson" ], "corpus_id": 202983186, "doc_id": "202983186", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "(INVITED) Methods for determining the refractive indices and thermo optic coefficients of chalcogenide glasses at MIR wavelengths", "venue": "Optical Materials: X", "year": 2019 }, { "abstract": "A new method (FTIR continuous dn dT method, n is refractive index and T temperature) for measuring the continuous thermo optic coefficients of thin transparent films in the mid infrared (MIR) spectral region is introduced. The technique is based on Fourier transform infrared (FTIR) transmission spectra measured at different temperatures. It is shown that this method can successfully determine the thermo optic coefficient of chalcogenide glass thin films (of batch compositions Ge20Sb10Se70 at. (atomic and Ge16As24Se15.5Te44.5 at. over the wavelength range from 2 to 25 um. The measurement precision error is less than 11.5 ppm degC over the wavelength range from 6 to 20 um. The precision is much better than that provided by the prism minimum deviation method or an improved Swanepoel method.", "author_names": [ "Yuanrong Fang", "David Furniss", "Dinuka Jayasuriya", "Harriet Parnell", "Zhuoqi Tang", "Angela B Seddon", "Trevor M Benson" ], "corpus_id": 199686852, "doc_id": "199686852", "n_citations": 3, "n_key_citations": 0, "score": 1, "title": "Determining the continuous thermo optic coefficients of chalcogenide glass thin films in the MIR region using FTIR transmission spectra.", "venue": "Optics express", "year": 2019 }, { "abstract": "Abstract Terahertz time domain spectroscopy has been used to measure the temperature dependent absorption coefficients and refractive indices of different polymers in 0.2 1.8 THz spectral frequency. The coefficients of temperature dependent Sellmeier equation for all these polymers have also been evaluated by statistical fitting the measured data, which will be helpful for the evaluation of dispersion properties of the material. Additionally, the thermo optic coefficients have been evaluated to be the range of 1.230 x 10 4 to 2.50 x 10 4 K 1 for 298 373 K. This data would be helpful for the applications of polymers as THz waveguide and other temperature sensitive devices. These results provide a temperature dependent database of optical properties of different polymers for their efficient utilization in THz technology.", "author_names": [ "Muhammad Bilal Mumtaz", "M Ahsan Mahmood", "Sabih D Khan", "M Aslam Zia", "Mushtaq Ahmed", "Izhar Ahmad" ], "corpus_id": 109294660, "doc_id": "109294660", "n_citations": 4, "n_key_citations": 0, "score": 1, "title": "Experimental measurement of temperature dependent sellmeier coefficients and thermo optic coefficients of polymers in terahertz spectral range", "venue": "Optical Materials", "year": 2019 }, { "abstract": "We have measured mass densities, thermo optic coefficients, and electronic polarizability of MoO3 thin films and of HxMoO3 and LixMoO3 bronze thin films over the temperature range from 100 K to 373 K using ellipsometry. The mass densities of MoO3 and molybdenum bronzes with different concentrations (x) changed from 3.76 g/cm3 to 2.45 g/cm3 during the heating and cooling cycles. Thermo optic coefficients (TOCs) or dn/dT and dk/dT values of the molybdenum bronzes were found to have anomalous dispersion in the heating cycles over the range 295 373 K. On the other hand, the values of dn/dT for MoO3 thin films and for ZxMoO3 bronzes were found to be negative and positive, respectively over the temperature range 100 295 K and were on the order of 10 4 K 1. The respective values of dk/dT were found to be positive and negative and were on the order of 10 4 K 1 in the same temperature range. A little increase in the values of TOCs for the molybdenum bronzes is due to small increase in electronic polarizability, which was calculated in the range from 8.20 to 8.22 x 10 24 cm3 over the temperature range 100 373 K. All these small values are due to creation of more amorphousness in the MoO3 structure during the cooling cycles. The n and k data and TOCs values of molybdenum bronzes are explained using analytical model. The reported ellipsometric data is also interpreted in terms of small polarons and bipolarons using configurational coordinate model.", "author_names": [ "Zahid Hussain" ], "corpus_id": 201656267, "doc_id": "201656267", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Ellipsometric Investigations of Electronic Polarizability and Thermo optic Coefficients of ZxMoO3 (Z H+ Li+ Bronzes", "venue": "Journal of Electronic Materials", "year": 2019 }, { "abstract": "The values of dn/dT for thermally evaporated WO3 thin films were found to be negative either in the heating cycle (295 373 K) or in the cooling cycle (100 300 K) and were found to be of order of 10 5 K 1. On the other hand thermo optic coefficients (TOCs: dn/dT and dk/dT values) of tungsten bronzes (H+ Li+ Na+ with different concentrations were found to be positive and negative, respectively in both the heating and cooling cycles and they were found to be in the order of 10 4 K 1. Heating cycles show hysteresis loops of n and k for tungsten bronzes, which are good for electrochromic devices. On heating the bronzes at temperature higher than 400 K, there might be a reduction in the porosity but an irreversible disordering of hydrogen, lithium or sodium atoms could occur because of anomalous dispersions produced in the optical data. For cooling cycles, the calculated TOCs were again of the order of 10 4 but there was an increase in dn/dT and a decrease in dk/dT values due to more amorphousness built up in the bronzes during the cooling cycles. This change in the values of TOCs for tungsten bronzes created small decrease in electronic polarizabilities (ae) which were calculated in the range from 8.003 to 8.02 x 10 24 cm3 in the cooling cycles.", "author_names": [ "Zahid Hussain" ], "corpus_id": 204196693, "doc_id": "204196693", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Thermo Optic Coefficients and Electronic Polarizabilities of Tungsten Bronzes Using Ellipsometry", "venue": "IEEE Photonics Journal", "year": 2019 }, { "abstract": "Abstract The development of thermo optic modulator elements for midwave infrared (MWIR) and longwave infrared (LWIR) electro optic systems, and the development of resistive thermometer elements for infrared imaging microbolometers require materials with high thermo optic coefficients (TOC) and high temperature coefficients of resistance (TCR) respectively. In this paper, we synthesize novel vanadium oxide (VxOy) thin film structures and measure their MWIR/LWIR thermo optic coefficients (TOCs) and their temperature coefficients of resistance (TCRs) The VxOy thin film are synthesized by sputter depositing interchanging, 5 nm thick, layers of vanadium sesquioxide (V2O3) and vanadium (V) reaching a final thin film thickness of 95 nm. The sputter deposited multilayer structures are then ex situ annealed in N2 and O2 atmospheres at 300 degC for 30 min. Infrared spectroscopic ellipsometry was used to measure the optical constants of the thin films as a function of temperature across the MWIR and LWIR bands (3000 14000 nm) The synthesized VxOy thin films exhibited high TOCs and high TCRs when operated in their semiconducting phase. A high TOC was measured reaching a maximum of 0.0278 degC 1 and 0.119 degC 1 at l 4000 nm for N2 and O2 annealed VxOy thin films respectively; and reaching a maximum of 0.0634 degC 1 and 0.139 degC 1 at l 10,000 nm for N2 and O2 annealed VxOy thin films respectively. Moreover, sheet resistance versus temperature measurements were conducted revealing room temperature sheet resistances of 1.495 k O/sq. and 1.516 k O/sq. and TCRs of 3.54%/degC and 3.46%/degC for N2 and O2 annealed VxOy thin films respectively.", "author_names": [ "Mohamed R Abdel-Rahman" ], "corpus_id": 125974018, "doc_id": "125974018", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Vanadium oxide thin films with high midwave longwave infrared thermo optic coefficients and high temperature coefficients of resistance", "venue": "", "year": 2018 }, { "abstract": "A microcavity fiber Fabry Perot interferometer (MFFPI) that is based on dual hollow core fibers (HCFs) is developed for measuring the thermo optic coefficients (TOCs) of liquids. The proposed MFFPI was fabricated by fusion splicing a tiny segment of the main HCF with a diameter D of 30 mm and another section of feeding HCF with a diameter of 5 mm. Then, the main HCF was filled with liquid by capillary action through the feeding HCF by immersing the MFFPI in the liquid. The TOCs of the Cargille liquid (n(D)=1.3) deionized (DI) water, and ethanol were accurately determined from the shift of the interference wavelength, which was due to the temperature variation. Our experimental results were also compared with other published studies to investigate the effectiveness of the proposed sensing scheme. The major advantage is that the miniature MFFPI can achieve the measurement of the TOCs of the liquids with picoliter volume, and the measured liquids also can be sealed off and stored inside the HCF to prevent contamination.", "author_names": [ "Cheng-Ling Lee", "Hsuan-Yu Ho", "Jheng-Hong Gu", "Tung-Yuan Yeh", "Chung-Hao Tseng" ], "corpus_id": 36465809, "doc_id": "36465809", "n_citations": 46, "n_key_citations": 1, "score": 0, "title": "Dual hollow core fiber based Fabry Perot interferometer for measuring the thermo optic coefficients of liquids.", "venue": "Optics letters", "year": 2015 }, { "abstract": "We report a method for compensation of errors caused by temperature fluctuations in refractive index measurements using Silicon photonic microring sensors. The method involves determination of resonance wavelength shifts caused by thermal fluctuations using real time measurement of on chip temperature variations and thermo optic coefficient (TOC) of analyte liquids. Resistive metal lines patterned around Silicon microrings are used to track temperature variations and TOC of analyte is calculated by measuring wavelength shifts caused by controlled increments in device temperature. The TOC of de ionized water is determined to be 1.12 x 10 4/degC, with an accuracy of 8.26 x 10 6/degC. In our system, chip surface temperature variations were measured with an instrument limited precision of 0.004 degC yielding a factor of 16 enhancement in tracking accuracy compared to conventional, bottom of chip temperature measurement. We show that refractive index detection limit of the microring sensor is also improved by the same factor.", "author_names": [ "Prashanth R Prasad", "Shankar Kumar Selvaraja", "Manoj M Varma" ], "corpus_id": 44137328, "doc_id": "44137328", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Real time compensation of errors in refractive index shift measurements of microring sensors using thermo optic coefficients.", "venue": "Optics express", "year": 2018 }, { "abstract": "Seventeen glasses in the Ge As Se ternary glass forming region have been fabricated and analyzed to provide input for optical design data and to establish composition and structure based relationships to aide development of novel chalcogenide glasses with tailored optical functionality. While known that Ge addition to binary As Se glasses enhances the mean coordination number (MCN) of the network and results in increased Tg and decreased CTE, this work highlights the impact on optical properties, specifically mid wave (l 4.515 mm) index and thermo optic coefficient (dn/dT) Trends in property changes were correlated with an excess or deficiency of chalcogen content in the glassy network as compared to stoichiometric compositions. Transitions in key optical properties were observed with the disappearance of Se Se homopolar bonds and creation of As As homopolar bonds which are associated with the Se rich and Se deficient regions near the stoichiometry, respectively. A second transition was observed with the creation of GeSe ethane like structures, which are only present in strongly Se deficient networks. Fitting dn/dT values with a simplified version of the thermal Lorentz Lorenz formulation yielded a linear relation between the quantity (n 3dn/dT) and the CTE, which can be used to predict compositions with the near zero dn/dT required for athermal optical systems.", "author_names": [ "Benn Gleason", "Kathleen Richardson", "Laura Sisken", "Charmayne E Smith" ], "corpus_id": 139079603, "doc_id": "139079603", "n_citations": 32, "n_key_citations": 1, "score": 0, "title": "Refractive Index and Thermo Optic Coefficients of Ge As Se Chalcogenide Glasses", "venue": "", "year": 2016 } ]

[ { "abstract": "Controlling magnetism via electric fields addresses fundamental questions of magnetic phenomena and phase transitions1 3, and enables the development of electrically coupled spintronic devices, such as voltage controlled magnetic memories with low operation energy4 6. Previous studies on dilute magnetic semiconductors such as (Ga,Mn)As and (In,Mn)Sb have demonstrated large modulations of the Curie temperatures and coercive fields by altering the magnetic anisotropy and exchange interaction2,4,7 9. Owing to their unique magnetic properties10 14, the recently reported two dimensional magnets provide a new system for studying these features15 19. For instance, a bilayer of chromium triiodide (CrI3) behaves as a layered antiferromagnet with a magnetic field driven metamagnetic transition15,16. Here, we demonstrate electrostatic gate control of magnetism in CrI3 bilayers, probed by magneto optical Kerr effect (MOKE) microscopy. At fixed magnetic fields near the metamagnetic transition, we realize voltage controlled switching between antiferromagnetic and ferromagnetic states. At zero magnetic field, we demonstrate a time reversal pair of layered antiferromagnetic states that exhibit spin layer locking, leading to a linear dependence of their MOKE signals on gate voltage with opposite slopes. Our results allow for the exploration of new magnetoelectric phenomena and van der Waals spintronics based on 2D materials.Electrical control of magnetism in a bilayer of CrI3 enables the realization of an electrically driven magnetic phase transition and the observation of the magneto optical Kerr effect in 2D magnets.", "author_names": [ "Bevin Huang", "Genevieve Clark", "D R Klein", "David MacNeill", "Efren Navarro-Moratalla", "Kyle L Seyler", "N P Wilson", "Michael A McGuire", "David H Cobden", "Di Xiao", "Wang Yao", "Pablo Jarillo-Herrero", "Xiaodong Xu" ], "corpus_id": 13751595, "doc_id": "13751595", "n_citations": 510, "n_key_citations": 1, "score": 1, "title": "Electrical control of 2D magnetism in bilayer CrI3", "venue": "Nature Nanotechnology", "year": 2018 }, { "abstract": "Monolayer valley semiconductors, such as tungsten diselenide (WSe2) possess valley pseudospin degrees of freedom that are optically addressable but degenerate in energy. Lifting the energy degeneracy by breaking time reversal symmetry is vital for valley manipulation. This has been realized by directly applying magnetic fields or via pseudomagnetic fields generated by intense circularly polarized optical pulses. However, sweeping large magnetic fields is impractical for devices, and the pseudomagnetic fields are only effective in the presence of ultrafast laser pulses. The recent rise of two dimensional (2D) magnets unlocks new approaches to controlling valley physics via van der Waals heterostructure engineering. Here, we demonstrate the wide continuous tuning of the valley polarization and valley Zeeman splitting with small changes in the laser excitation power in heterostructures formed by monolayer WSe2 and 2D magnetic chromium triiodide (CrI3) The valley manipulation is realized via the optical control of the CrI3 magnetization, which tunes the magnetic exchange field over a range of 20 T. Our results reveal a convenient new path toward the optical control of valley pseudospins and van der Waals magnetic heterostructures.", "author_names": [ "Kyle L Seyler", "Ding Zhong", "Bevin Huang", "Xiayu Linpeng", "N P Wilson", "Takashi Taniguchi", "Kenji Watanabe", "Wang Yao", "Di Xiao", "Michael A McGuire", "Kai-Mei C Fu", "Xiaodong Xu" ], "corpus_id": 21675035, "doc_id": "21675035", "n_citations": 119, "n_key_citations": 0, "score": 0, "title": "Valley Manipulation by Optically Tuning the Magnetic Proximity Effect in WSe2/CrI3 Heterostructures.", "venue": "Nano letters", "year": 2018 }, { "abstract": "An intrinsic magnetic tunnel junction An electrical current running through two stacked magnetic layers is larger if their magnetizations point in the same direction than if they point in opposite directions. These so called magnetic tunnel junctions, used in electronics, must be carefully engineered. Two groups now show that high magnetoresistance intrinsically occurs in samples of the layered material CrI3 sandwiched between graphite contacts. By varying the number of layers in the samples, Klein et al. and Song et al. found that the electrical current running perpendicular to the layers was largest in high magnetic fields and smallest near zero field. This observation is consistent with adjacent layers naturally having opposite magnetizations, which align parallel to each other in high magnetic fields. Science, this issue p. 1218, p. 1214 The atomic layers of the material CrI3 act as spin filters in graphite/CrI3/graphite junctions. Magnetic multilayer devices that exploit magnetoresistance are the backbone of magnetic sensing and data storage technologies. Here, we report multiple spin filter magnetic tunnel junctions (sf MTJs) based on van der Waals (vdW) heterostructures in which atomically thin chromium triiodide (CrI3) acts as a spin filter tunnel barrier sandwiched between graphene contacts. We demonstrate tunneling magnetoresistance that is drastically enhanced with increasing CrI3 layer thickness, reaching a record 19,000% for magnetic multilayer structures using four layer sf MTJs at low temperatures. Using magnetic circular dichroism measurements, we attribute these effects to the intrinsic layer by layer antiferromagnetic ordering of the atomically thin CrI3. Our work reveals the possibility to push magnetic information storage to the atomically thin limit and highlights CrI3 as a superlative magnetic tunnel barrier for vdW heterostructure spintronic devices.", "author_names": [ "Tiancheng Song", "Xinghan Cai", "Matisse Wei-Yuan Tu", "Xiaoou Zhang", "Bevin Huang", "N P Wilson", "Kyle L Seyler", "Lin Zhu", "Takashi Taniguchi", "Kenji Watanabe", "Michael A McGuire", "David H Cobden", "Di Xiao", "Wang Yao", "Xiaodong Xu" ], "corpus_id": 19218986, "doc_id": "19218986", "n_citations": 484, "n_key_citations": 3, "score": 0, "title": "Giant tunneling magnetoresistance in spin filter van der Waals heterostructures", "venue": "Science", "year": 2018 }, { "abstract": "A van der Waals heterostructure of monolayer WSe2 and ferromagnetic CrI3 enables exceptional control of valley pseudospin. The integration of magnetic material with semiconductors has been fertile ground for fundamental science as well as of great practical interest toward the seamless integration of information processing and storage. We create van der Waals heterostructures formed by an ultrathin ferromagnetic semiconductor CrI3 and a monolayer of WSe2. We observe unprecedented control of the spin and valley pseudospin in WSe2, where we detect a large magnetic exchange field of nearly 13 T and rapid switching of the WSe2 valley splitting and polarization via flipping of the CrI3 magnetization. The WSe2 photoluminescence intensity strongly depends on the relative alignment between photoexcited spins in WSe2 and the CrI3 magnetization, because of ultrafast spin dependent charge hopping across the heterostructure interface. The photoluminescence detection of valley pseudospin provides a simple and sensitive method to probe the intriguing domain dynamics in the ultrathin magnet, as well as the rich spin interactions within the heterostructure.", "author_names": [ "Ding Zhong", "Kyle L Seyler", "Xiayu Linpeng", "Ran Cheng", "Nikhil Sivadas", "Bevin Huang", "Emma Schmidgall", "Takashi Taniguchi", "Kenji Watanabe", "Michael A McGuire", "Wang Yao", "Di Xiao", "Kai-Mei C Fu", "Xiaodong Xu" ], "corpus_id": 10426963, "doc_id": "10426963", "n_citations": 370, "n_key_citations": 2, "score": 0, "title": "Van der Waals engineering of ferromagnetic semiconductor heterostructures for spin and valleytronics", "venue": "Science Advances", "year": 2017 }, { "abstract": "Description", "author_names": [ "Tiancheng Song", "Eric Anderson", "Matisse Wei-Yuan Tu", "Kyle L Seyler", "Takashi Taniguchi", "Kenji Watanabe", "Michael A McGuire", "Xiaosong Li", "Ting Cao", "Di Xiao", "Wang Yao", "Xiaodong Xu" ], "corpus_id": 231986578, "doc_id": "231986578", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Spin photovoltaic effect in magnetic van der Waals heterostructures", "venue": "Science advances", "year": 2021 }, { "abstract": "We have synthesized unique colloidal nanoplatelets of the two dimensional (2D) van der Waals ferromagnet CrI3 and have characterized these nanoplatelets structurally, magnetically, and by magnetic circular dichroism spectroscopy. The CrI3 nanoplatelets have lateral dimensions of ~25 nm and thicknesses of only ~4 nm, corresponding to just a few CrI3 monolayers. Magnetic and magneto optical measurements demonstrate robust 2D ferromagnetic ordering with Curie temperatures similar to bulk CrI3, despite their small size. These data also show magnetization steps akin to those observed in micron sized few layer 2D sheets associated with concerted spin reversal of individual CrI!3 layers within few layer van der Waals stacks. Similar data have also been obtained for CrBr3 and anion alloyed Cr(I1 xBrx)3 nanoplatelets. These results represent the first example of lateral nanostructures of 2D van der Waals ferromagnets of any composition. The demonstration of robust ferromagnetism at nanometer lateral dimensions opens new doors for miniaturization in spintronics devices based on van der Waals ferromagnets.", "author_names": [ "Michael C De Siena", "Sidney E Creutz", "Annie Regan", "Paul Malinowski", "Qianni Jiang", "Kyle T Kluherz", "Guomin Zhu", "Zhong Lin", "James J De Yoreo", "Xiaodong Xu", "Jiun Haw Chu", "Daniel R Gamelin" ], "corpus_id": 210473134, "doc_id": "210473134", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "2D van der Waals Nanoplatelets with Robust Ferromagnetism.", "venue": "Nano letters", "year": 2020 }, { "abstract": "The coupling between spin and charge degrees of freedom in a crystal gives rise to magneto optical effects with applications in the sensitive detection of local magnetic order, optical modulation and data storage. In two dimensional magnets these effects manifest themselves in the large magneto optical Kerr effect1,2, spontaneous helical light emission3,4 from ferromagnetic (FM) monolayers and electric field induced Kerr rotation5 7 and giant second order non reciprocal optical effects8 in antiferromagnetic (AFM) bilayers. Here we demonstrate the tuning of inelastically scattered light through symmetry control in atomically thin chromium triiodide (CrI3) In monolayers, we found an extraordinarily large magneto optical Raman effect from an A1g phonon mode due to the emergence of FM order. The linearly polarized, inelastically scattered light rotates by ~40deg, more than two orders of magnitude larger than the rotation from the magneto optical Kerr effect under the same experimental conditions. In CrI3 bilayers, the same phonon mode becomes Davydov split into two modes of opposite parity, which exhibit divergent selection rules that depend on inversion symmetry and the underlying magnetic order. We demonstrate the magneto electrical control over these selection rules by activating or suppressing Raman activity for the odd parity phonon mode and the magneto optical rotation of scattered light from the even parity phonon mode. Our work underlines the unique opportunities provided by two dimensional magnets to control the combined time reversal and inversion symmetries to manipulate Raman optical selection rules and for exploring emergent magneto optical effects and spin phonon coupled physics.Symmetry control in atomically thin chromium triiodide enables the observation of tunable magneto optical Raman effects in the 2D limit.", "author_names": [ "Bevin Huang", "John Cenker", "Xiaoou Zhang", "Essance L Ray", "Tiancheng Song", "Takashi Taniguchi", "Kenji Watanabe", "Michael A McGuire", "Di Xiao", "Xiaodong Xu" ], "corpus_id": 203736463, "doc_id": "203736463", "n_citations": 38, "n_key_citations": 0, "score": 0, "title": "Tuning inelastic light scattering via symmetry control in the two dimensional magnet CrI3", "venue": "Nature Nanotechnology", "year": 2020 }, { "abstract": "Layered antiferromagnetism is the spatial arrangement of ferromagnetic layers with antiferromagnetic interlayer coupling. The van der Waals magnet chromium triiodide (CrI3) has been shown to be a layered antiferromagnetic insulator in its few layer form1, opening up opportunities for various functionalities2 7 in electronic and optical devices. Here we report an emergent nonreciprocal second order nonlinear optical effect in bilayer CrI3. The observed second harmonic generation (SHG; a nonlinear optical process that converts two photons of the same frequency into one photon of twice the fundamental frequency) is several orders of magnitude larger than known magnetization induced SHG8 11 and comparable to the SHG of the best (in terms of nonlinear susceptibility) two dimensional nonlinear optical materials studied so far12,13 (for example, molybdenum disulfide) We show that although the parent lattice of bilayer CrI3 is centrosymmetric, and thus does not contribute to the SHG signal, the observed giant nonreciprocal SHG originates only from the layered antiferromagnetic order, which breaks both the spatial inversion symmetry and the time reversal symmetry. Furthermore, polarization resolved measurements reveal underlying C2h crystallographic symmetry and thus monoclinic stacking order in bilayer CrI3, providing key structural information for the microscopic origin of layered antiferromagnetism14 18. Our results indicate that SHG is a highly sensitive probe of subtle magnetic orders and open up possibilities for the use of two dimensional magnets in nonlinear and nonreciprocal optical devices.Large second harmonic generation is observed in antiferromagnetic bilayers of CrI3, providing information about the microscopic origin of layered antiferromagnetism and motivating the use of two dimensional magnets in nonlinear optical devices.", "author_names": [ "Zeyuan Sun", "Yangfan Yi", "Tiancheng Song", "Genevieve Clark", "Bevin Huang", "Yuwei Shan", "Shuang Wu", "Di Huang", "Chunlei Gao", "Zhanghai Chen", "Michael A McGuire", "Ting Cao", "Di Xiao", "Wei-Tao Liu", "Wang Yao", "Xiaodong Xu", "Shiwei Wu" ], "corpus_id": 102351120, "doc_id": "102351120", "n_citations": 138, "n_key_citations": 1, "score": 0, "title": "Giant nonreciprocal second harmonic generation from antiferromagnetic bilayer CrI3", "venue": "Nature", "year": 2019 }, { "abstract": "Magnetic anisotropy is crucially important for the stabilization of two dimensional (2D) magnetism, which is rare in nature but highly desirable in spintronics and for advancing fundamental knowledge. Recent works on CrI3 and CrGeTe3 monolayers not only led to observations of the long time sought 2D ferromagnetism, but also revealed distinct magnetic anisotropy in the two systems, namely Ising behavior for CrI3 versus Heisenberg behavior for CrGeTe3. Such magnetic difference strongly contrasts with structural and electronic similarities of these two materials, and understanding it at a microscopic scale should be of large benefits. Here, first principles calculations are performed and analyzed to develop a simple Hamiltonian, to investigate magnetic anisotropy of CrI3 and CrGeTe3 monolayers. The anisotropic exchange coupling in both systems is surprisingly determined to be of Kitaev type. Moreover, the interplay between this Kitaev interaction and single ion anisotropy (SIA) is found to naturally explain the different magnetic behaviors of CrI3 and CrGeTe3. Finally, both the Kitaev interaction and SIA are further found to be induced by spin orbit coupling of the heavy ligands (I of CrI3 or Te of CrGeTe3) rather than the commonly believed 3d magnetic Cr ions.Monolayer magnetism: Kitaev interaction comes into playInterplay between two anisotropic interactions Kitaev and single ion is responsible for magnetism in ferromagnetic thin films. Teams led by Hongjun Xiang at Fudan University in China and Laurent Bellaiche at the University of Arkansas in the US led to the use of first principles calculations to elucidate magnetic anisotropy in two different two dimensional ferromagnetic materials with different magnetic behaviors. By developing a predictive Hamiltonian and a tight binding model, the origin of two dimensional magnetism in chromium iodine and chromium germanium tellurium monolayers was revealed to be Kitaev interactions and their interplay with single ion anisotropy. Both the Kitaev and single ion anisotropies were induced by the spin orbit coupling of the heavy ligand elements iodine and tellurium. Research into Kitaev interactions in unconventional systems may contribute towards better understanding of interesting physics.", "author_names": [ "Changsong Xu", "Junsheng Feng", "Hongjun Xiang", "Laurent Bellaiche" ], "corpus_id": 53696927, "doc_id": "53696927", "n_citations": 112, "n_key_citations": 1, "score": 0, "title": "Interplay between Kitaev interaction and single ion anisotropy in ferromagnetic CrI3 and CrGeTe3 monolayers", "venue": "npj Computational Materials", "year": 2018 }, { "abstract": "Stacking order can influence the physical properties of two dimensional van der Waals materials1,2. Here we applied hydrostatic pressure up to 2 GPa to modify the stacking order in the van der Waals magnetic insulator CrI3. We observed an irreversible interlayer antiferromagnetic to ferromagnetic transition in atomically thin CrI3 by magnetic circular dichroism and electron tunnelling measurements. The effect was accompanied by a monoclinic to rhombohedral stacking order change characterized by polarized Raman spectroscopy. Before the structural change, the interlayer antiferromagnetic coupling energy can be tuned up by nearly 100% with pressure. Our experiment reveals the interlayer ferromagnetic ground state, which is established in bulk CrI3 but not observed in native exfoliated thin films. The observed correlation between the magnetic ground state and the stacking order is in good agreement with first principles calculations3 8 and suggests a route towards nanoscale magnetic textures by moire engineering3,9. Pressure induced changes in the magnetic order of atomically thin van der Waals crystals are revealed and attributed to changes in the stacking arrangement.", "author_names": [ "Tingxin Li", "Shengwei Jiang", "Nikhil Sivadas", "Zefang Wang", "Yang Xu", "Daniel Weber", "Joshua E Goldberger", "Kenji Watanabe", "Takashi Taniguchi", "Craig J Fennie", "Kin Fai Mak", "Jie Shan" ], "corpus_id": 166228052, "doc_id": "166228052", "n_citations": 138, "n_key_citations": 2, "score": 0, "title": "Pressure controlled interlayer magnetism in atomically thin CrI3", "venue": "Nature Materials", "year": 2019 } ]