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[ { "abstract": "Phenomenological models for the internal quantum efficiency of Schottky barrier photodetectors suitable for the detection of optical radiation below the bandgap energy of the semiconductor are presented and discussed. The detection mechanism is internal photoemission from the metal film into the semiconductor substrate. Three detector configurations are considered: the first consists of a thick metal film on a semiconductor substrate forming a single Schottky barrier; the second consists of a thin metal film on a semiconductor substrate also forming a single Schottky barrier; and the third consists of a thin metal film buried in semiconductor and forming two Schottky barriers (one along each metal semiconductor interface) In the three cases, illumination through the semiconductor substrate is assumed. The two thin film configurations provide enhanced internal quantum efficiencies due to multiple hot carrier reflections within the metal film, with the double barrier case providing the greatest enhancement due to emission over two barriers. The models proposed are based on assessing the emission probability of hot carriers as a function of their energy, taking into account multiple reflections within the metal film and energy losses due to internal scattering (e.g. with phonons and cold carriers) The thin film single barrier model was tested via comparisons with responsivity measurements reported in the literature for PtSi/p Si and Pd2Si/p Si detectors.", "author_names": [ "Christine Scales", "Pierre Berini" ], "corpus_id": 43229071, "doc_id": "43229071", "n_citations": 197, "n_key_citations": 14, "score": 1, "title": "Thin Film Schottky Barrier Photodetector Models", "venue": "IEEE Journal of Quantum Electronics", "year": 2010 }, { "abstract": "It is generally believed that the resistance degradation behavior of bulk and thin film oxide capacitors arises from the oxygen vacancy migration within the oxide and/or the charge injection at the oxide/electrode interface. The magnitude of the degradation in the resistance has been theoretically studied in the literature by solving the electrochemical transport equations while assuming constant Schottky barrier height. The treatment of constant Schottky barrier height in existing models has led to significant underestimation of the resistance degradation. In this work, I incorporated the dependence of Schottky barrier height on the oxygen vacancy concentration at the interface into the existing model to simulate the degradation process in thin film oxide capacitors. With the consideration of Schottky barrier height lowering from the interface dipole arising from the accumulation of oxygen vacancies at the cathode interface, I found that the leakage current can be increased by more than one order of magnitude, which is more consistent with experimental observations in comparison to the prediction from existing models.", "author_names": [ "Feng Xue" ], "corpus_id": 233911676, "doc_id": "233911676", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Effect of Schottky barrier height lowering on resistance degradation of Fe doped SrTiO3 thin film capacitor", "venue": "", "year": 2021 }, { "abstract": "Abstract. A two dimensional model was developed to simulate the optoelectronic characteristics of indium gallium nitride (InxGa1 xN) thin film, Schottky barrier solar cells. The solar cells comprise a window designed to reduce the reflection of incident light, Schottky barrier and ohmic front electrodes, an n doped InxGa1 xN wafer, and a metallic periodically corrugated backreflector. The ratio of indium to gallium in the wafer varies periodically throughout the thickness of absorbing layer of the solar cell. Thus, the resulting InxGa1 xN wafer's optical and electrical properties are made to vary periodically. This material nonhomogeneity could be physically achieved by varying the fractional composition of indium and gallium during deposition. Empirical models for indium nitride and gallium nitride were combined using Vegard's law to determine the optical and electrical constitutive properties of the alloy. The nonhomogeneity of the electrical properties of the InxGa1 xN aids in the separation of the excited electron hole pairs, whereas the periodicities of optical properties and the backreflector enable the incident light to couple to multiple guided wave modes. The profile of the resulting charge carrier generation rate when the solar cell is illuminated by the AM1.5G spectrum was calculated using the rigorous coupled wave approach. The steady state drift diffusion equations were solved using COMSOL, which employs finite volume methods, to calculate the current density as a function of the voltage. Midband Shockley Read Hall, Auger, and radiative recombination rates were taken to be the dominant methods of recombination. The model was used to study the effects of the solar cell geometry and the shape of the periodic material nonhomogeneity on efficiency. The solar cell efficiency was optimized using the differential evolution algorithm.", "author_names": [ "Tom H Anderson", "Akhlesh Lakhtakia", "Peter B Monk" ], "corpus_id": 55221823, "doc_id": "55221823", "n_citations": 9, "n_key_citations": 1, "score": 0, "title": "Optimization of nonhomogeneous indium gallium nitride Schottky barrier thin film solar cells", "venue": "", "year": 2018 }, { "abstract": "In the present article, we proposed a p n homojunction photodetector with a series Schottky barrier and a high value of responsivity in the ultraviolet region. The thin film photodetector makes use of a junction between an RF sputtered n type ZnO nanostructure and a p type copper doped ZnO (CZO) thin film derived through the spin coating process on an ITO coated glass substrate. Palladium metal contacts have been deposited to form the Schottky barrier in series with the p n homojunction. The device has been simulated, fabricated, and tested only after ensuring the stability of the p type CZO thin film. The measured I V characteristics of the fabricated photodetector under illuminated and dark conditions showed excellent UV response and good rectification properties. The device exhibits a peak responsivity of 13.2 A W 1 for a reverse biasing voltage of 3 V. This value is much higher than the values reported by others for a ZnO based photodetector.", "author_names": [ "Lucky Agarwal", "Shweta Tripathi" ], "corpus_id": 212761495, "doc_id": "212761495", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "High responsivity ZnO based p n homojunction UV photodetector with series Schottky barrier", "venue": "", "year": 2020 }, { "abstract": "The application of Schottky junction in self powered devices is limited by low efficiency in both separation and transport of photogenerated electrons/holes. This issue may be overcome by introducing electronically conductive metal organic framework (EC MOF) materials into the junction and limited by preparing high quality thin films of EC MOFs. In this study, for the first time, high quality EC MOF thin films were demonstrated as effective interlayer materials to solve the above mentioned issue by modulating the height of Schottky barrier (PhB) The EC MOF based self powered Schottky diode can act as a photodetector and demonstrate the highest external quantum efficiency (84% for all reported self powered photodetectors as well as the broadest detectable spectrum range (250 to 1500 nm) high on off ratio ~103) and short rise (0.007 s) and fall time (0.03 s) Furthermore, it can be used as a gas sensor for typical harmful gases and vapors.", "author_names": [ "Linan Cao", "Ming-Shui Yao", "Huijie Jiang", "Susumu Kitagawa", "Xiaoliang Ye", "Wenhua Li", "Gang Xu" ], "corpus_id": 218825848, "doc_id": "218825848", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "A highly oriented conductive MOF thin film based Schottky diode for self powered light and gas detection", "venue": "", "year": 2020 }, { "abstract": "Abstract A single crystalline ZnGa2O4 epilayer was successfully grown on a c plane (0001) sapphire substrate through metalorganic chemical vapor deposition. A metal semiconductor metal Schottky deep ultraviolet (DUV) photodetector based on a ZnGa2O4 thin film was fabricated through a simple process of E gun evaporation and thermal annealing. At a bias of 10 V, the ZnGa2O4 photodetectors exhibited excellent performance characteristics such as an extremely low dark current (0.86 pA) a responsivity of 0.46 A/W under 230 nm DUV, a high photo/dark current ratio (up to 4.68 x 104) a sharp cutoff wavelength of approximately 270 nm, and short rise and fall times of 0.96 and 0.34 s. The photogenerated holes trapped in the Schottky barrier and the shrinking of the depletion region under DUV illumination enabled high DUV/visible rejection ratio (3 4 orders with a 20 V bias) Therefore, the Fowler Nordheim field tunneling emission functioned as the main electron transport mechanism under DUV illumination and improved the photoelectric characteristics of the epilayer.", "author_names": [ "Chiung-yi Huang", "Ray-Hua Horng" ], "corpus_id": 202219308, "doc_id": "202219308", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Deep ultraviolet Schottky photodetectors with high deep ultraviolet/visible rejection based on a ZnGa2O4 thin film", "venue": "", "year": 2019 }, { "abstract": "Ferroelectrics are considered next generation photovoltaic (PV) materials. In this work, a switchable and large PV effect is demonstrated in a Pb free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 0.5(Ba0.7Ca0.3)TiO3 (BZT BCT) thin film fabricated by a pulsed laser deposition technique. The material shows a remarkable PV output of 0.81 V due to its morphotropic phase boundary composition. The observed PV effect is analyzed on the basis of the interfacial Schottky barrier and bulk depolarization field. The poling dependent PV studies revealed that although the Schottky and depolarization field contribute to the PV effect, the latter dominates the PV response beyond the coercive field. Additionally, the importance of this compound in the field of a self biased photodetector is elucidated in terms of calculated photodetector parameters such as responsivity and detectivity. The explored results will bring significant advancement in the field of ferroelectric PV, UV solid state detector applications and also give an additional dimension to the multifunctional ability of the BZT BCT system.Ferroelectrics are considered next generation photovoltaic (PV) materials. In this work, a switchable and large PV effect is demonstrated in a Pb free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 0.5(Ba0.7Ca0.3)TiO3 (BZT BCT) thin film fabricated by a pulsed laser deposition technique. The material shows a remarkable PV output of 0.81 V due to its morphotropic phase boundary composition. The observed PV effect is analyzed on the basis of the interfacial Schottky barrier and bulk depolarization field. The poling dependent PV studies revealed that although the Schottky and depolarization field contribute to the PV effect, the latter dominates the PV response beyond the coercive field. Additionally, the importance of this compound in the field of a self biased photodetector is elucidated in terms of calculated photodetector parameters such as responsivity and detectivity. The explored results will bring significant advancement in the field of ferroelectric PV, UV solid state detector applications and also give an addit.", "author_names": [ "Atal Bihari Swain", "Martando Rath", "Pranab Parimal Biswas", "Mamidanna Sri Ramachandra Rao", "Pattukkannu Murugavel" ], "corpus_id": 104473517, "doc_id": "104473517", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Polarization controlled photovoltaic and self powered photodetector characteristics in Pb free ferroelectric thin film", "venue": "", "year": 2019 }, { "abstract": "A two dimensional model was developed to simulate the optoelectronic characteristics of indium gallium nitride (InxGa1 xN) thin film, Schottky barrier junction solar cells. The solar cell comprises a window designed to reduce the reflection of incident light, Schottky barrier and ohmic front electrodes, an n doped InxGa1 xN wafer, and a metallic periodically corrugated back reflector (PCBR) The ratio of indium to gallium in the wafer varies periodically in the thickness direction, and thus the optical and electrical constitutive properties of the alloy also vary periodically. This material nonhomogeneity could be physically achieved by varying the fractional composition of indium and gallium during deposition. Empirical models for indium nitride and gallium nitride, combined with Vegard's law, were used to calculate the optical and electrical constitutive properties of the alloy. The periodic nonhomogeneity aids charge separation and, in conjunction with the PCBR, enables incident light to couple to multiple surface plasmon polariton waves and waveguide modes. The profile of the resulting chargecarrier generation rate when the solar cell is illuminated by the AM1.5G spectrum was calculated using the rigorous coupled wave approach. The steady state drift diffusion equations were solved using COMSOL, which employs finite element methods, to calculate the current density as a function of the voltage. Mid band Shockley Read Hall, Auger, and radiative recombination rates were taken to be the dominant methods of recombination. The model was used to study the effects of the solar cell geometry and the shape of the periodic material nonhomogeneity on efficiency. The solar cell efficiency was optimized using the differential evolution algorithm.", "author_names": [ "Tom H Anderson", "Akhlesh Lakhtakia", "Peter B Monk" ], "corpus_id": 139549048, "doc_id": "139549048", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Optimal indium gallium nitride Schottky barrier thin film solar cells", "venue": "Optical Engineering Applications", "year": 2017 }, { "abstract": "The switchable ferroelectric photovoltaic (FPV) effect facilitates application of multifunctional photoelectric devices. The drawback of the FPV effect is that it generates a very low photocurrent in highly insulated ferroelectric materials. In contrast, the light induced pyroelectric effect enhances photoelectric performance. Both effects strongly depend on the ferroelectric polarization of the material. In this study, we fabricated and characterized a near ultraviolet photodetector consisting of a Pt/hexagonal TmFeO3/Pt heterojunction. The switchable FPV and light induced pyroelectric effects are both observed in a hexagonal TmFeO3 ferroelectric semiconductor film. An additional potential arises from the light induced pyroelectric effect, which strongly depends on the light intensity. The Schottky barrier height can be modulated by both the poling electric field and light induced pyroelectric potential. Increasing the power density above the threshold leads to switchable polarization via the light induced pyroelectric potential. The coexistence of photovoltaic and pyroelectric effects in the hexagonal TmFeO3 ferroelectric semiconductor makes it possible to develop electronic, thermal, and optical sensors as well as energy conversion devices.The switchable ferroelectric photovoltaic (FPV) effect facilitates application of multifunctional photoelectric devices. The drawback of the FPV effect is that it generates a very low photocurrent in highly insulated ferroelectric materials. In contrast, the light induced pyroelectric effect enhances photoelectric performance. Both effects strongly depend on the ferroelectric polarization of the material. In this study, we fabricated and characterized a near ultraviolet photodetector consisting of a Pt/hexagonal TmFeO3/Pt heterojunction. The switchable FPV and light induced pyroelectric effects are both observed in a hexagonal TmFeO3 ferroelectric semiconductor film. An additional potential arises from the light induced pyroelectric effect, which strongly depends on the light intensity. The Schottky barrier height can be modulated by both the poling electric field and light induced pyroelectric potential. Increasing the power density above the threshold leads to switchable polarization via the light induc.", "author_names": [ "Lichuan Jin", "Dainan Zhang", "Huaiwu Zhang", "Miaoqing Wei", "Zhiyong Zhong" ], "corpus_id": 213090000, "doc_id": "213090000", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Near ultraviolet photodetector based on hexagonal TmFeO3 ferroelectric semiconductor thin film with photovoltaic and pyroelectric effects", "venue": "", "year": 2019 }, { "abstract": "Abstract. Schottky barrier photodetector (PD) (tungsten/nickel/aluminum nitride) based on stacked tungsten gratings is reported in our work. The absorbance of the grating based structure is obtained using rigorous coupled wave analysis method. In addition, a responsivity value of 6.164 mA W is calculated at l 559.38 nm based on Fowler's model. More than three times enhancement in responsivity is achieved as compared with that of bulk structure (without grating) based Schottky barrier PD. In addition, a detectivity value of 33.11 x 1011 cm Hz1/2 W is obtained. Furthermore, the effect of grating variables and incident angle on responsivity are also demonstrated. In future, the proposed structure can also be used as a plasmonic sensor, absorber, or spectral filter.", "author_names": [ "Ankit Kumar Pandey", "Anuj Kumar Sharma" ], "corpus_id": 226369917, "doc_id": "226369917", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Schottky barrier photodetector utilizing tungsten grating nanostructure", "venue": "", "year": 2020 } ]

[ { "abstract": "While high mobility p type conjugated polymers have been widely reported, high mobility n type conjugated polymers are still rare. In the present work, we designed semifluorinated alkyl side chains and introduced them into naphthalene diimide based polymers (PNDIF T2 and PNDIF TVT) We found that the strong self organization of these side chains induced a high degree of order in the attached polymer backbones by forming a superstructure composed of \"backbone crystals\" and \"side chain crystals\" This phenomenon was shown to greatly enhance the ordering along the backbone direction, and the resulting polymers thus exhibited unipolar n channel transport in field effect transistors with remarkably high electron mobility values of up to 6.50 cm(2) V( 1) s( 1) and with a high on off current ratio of 10(5)", "author_names": [ "Boseok Kang", "Ran Kim", "Seon Baek Lee", "Soon-Ki Kwon", "Yun-Hi Kim", "Kilwon Cho" ], "corpus_id": 207160974, "doc_id": "207160974", "n_citations": 157, "n_key_citations": 0, "score": 1, "title": "Side Chain Induced Rigid Backbone Organization of Polymer Semiconductors through Semifluoroalkyl Side Chains.", "venue": "Journal of the American Chemical Society", "year": 2016 }, { "abstract": "Abstract The chain conformation of poly(2 vinylpyridine) (P2VP) complexed by 4 (4 (3,4,5 tris(dodecyloxy)benzoyl)oxy)phenyl)diazenyl)benzenesulfonic acid at different degrees of neutralization (DN) was addressed by small and wide angle neutron scattering technique. To get information on the conformation of P2VP chains spatially confined within lamellar and columnar mesophases at different DNs, the complexes were prepared from a blend of protonated and deuterated P2VP. The 2D scattering patterns of extruded fibers show that at low DN the complex self organizes in a lamellar phase. The inertial mean distances in the direction parallel and perpendicular to the fiber axis reveal the formation of compact disc like globules of individual P2VP chains at DN 25 and 33% With the increase of DN the interaction between the neighboring side groups along the backbone increases. This results in formation of hexagonal columnar phase at DN 50% in which the P2VP macromolecules are confined within cylindrical channels forming most probably a disordered helical conformation. At DN 1.0, the enhanced rigidity of the complex hinders the accommodation of the ligands at the interface with polymer chain. This results in appearance of non bonded side groups in the columns giving rise to a poorly ordered structure. In contrast to more rigid chains of poly(4 vinylpyridine) the transition from lamellar to columnar mesophase in P2VP occurs at lower DNs, indicating a significant role of the chain flexibility in the formation of ordered structures.", "author_names": [ "Denis V Anokhin", "Kseniia N Grafskaia", "Inessa A Izdelieva", "Xiaomin Zhu", "Dimitri A Ivanov" ], "corpus_id": 107570416, "doc_id": "107570416", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Polymer conformation in supramolecular complexes with wedge shaped ligands: Exploring the impact of the liquid crystalline organization", "venue": "Polymer", "year": 2019 }, { "abstract": "Comb like macromolecules 3 nnn consisting of poly(p phenylene vinylene)/poly(p phenylene ethynylene) polymer backbones bearing four flexible alkoxy substituents per constitutional unit are examined in their bulk states with respect to the length of the side chains attached on the phenylene ring located between the vinylene moities. Characterization of phase behaviour has been performed by means of polarized optical microscopy and differential scanning calorimetry. Structural ordering on the molecular size scale was deduced from a qualitative analysis of wide angle X ray scattering effects recorded for macroscopically oriented filaments using a two dimensional detector. Macromonomer 1 was also considered. All experimental results pointed out a highly ordered self organization of these materials with structure parameters depending on molecular details. For both macromonomer 1 and polymers 3 nnn, formation of supramolecular assemblies is detected as temperature dependent contributions of (1) spatial segregation between aromatic and aliphatic segments, (2) stacking properties of p conjugated fragments and (3) crystallization of the alkoxy side chains.", "author_names": [ "Benjamin Carbonnier", "Tadeusz Pakula", "Daniel Ayuk Mbi Egbe" ], "corpus_id": 98100361, "doc_id": "98100361", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Self organization of comb like macromolecules comprised of four fold alkoxy substituted (PPV PPE) rigid backbone repeat units: role of length variation of side chains attached on phenylene ring surrounded by vinylene moieties", "venue": "", "year": 2005 }, { "abstract": "Abstract 4 Hydroxy 4' cyanobiphenyl and 4 hydroxy 4' n pentylbiphenyl have been converted into vinyl monomers by reactions with acryloyl and methacryloyl chlorides. All four new monomers were homopolymerized free radically to yield acrylic polymers which melt with decomposition at temperatures in excess of 200degC. Powder X ray diffraction studies clearly show that the polymers are crystalline and suggest that the polymer backbones lie in essentially parallel planes contained within perpendicular smectic like layers of the directly attached and rigid anisotropic side chain substituents. It is noteworthy that side chain ordering is sufficiently strong to overcome the normal conformational barriers associated with main chain methyl groups in the methacrylate polymers. Previous examples of this type of ordering have been restricted to acrylate polymers.", "author_names": [ "A K Alimoglu", "Anthony Ledwith", "Peter Alan Gemmell", "George William Gray", "Dana Borden Lacy" ], "corpus_id": 98715253, "doc_id": "98715253", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Polymers with rigid anisotropic side groups: 1. Side chain induced crystallinity in substituted biphenyl acrylates and methacrylates", "venue": "", "year": 1984 }, { "abstract": "Abstract The synthesis, characterization and supramolecular organization of rigid flexible aromatic aliphatic polyethers are reported. The polymers contain substituted quinquephenyl moieties along their main chains separated by flexible aliphatic units of various lengths. The oligophenylene segments bear different types of dodecyloxy tailed side groups, either attached on the periphery of side dendritic wedges (G 1 or as direct side chains (G 0 Their structural characterization was performed by means of differential scanning calorimetry, polarizing optical microscopy and X ray scattering from oriented fibers. These techniques revealed the presence of supramolecular organization in different levels and in the absence of solvent, reflecting a delicate balance of interactions produced by the rigid flexible backbone segments and the size of dendritic side chains. It was concluded that the polymers with only two dodecyloxy side chains (zeroth generation, G 0 possess smectic order. On the other hand, substitution of the quinquephenyl backbone with the dodecyloxy decorated dendrons (first generation, G 1 disrupts the lateral order giving rise to a nematic state. These results are compared with the corresponding rigid flexible polyethers having terphenyl rigid segments.", "author_names": [ "P Riala", "Aikaterini K Andreopoulou", "Joannis K Kallitsis", "Antonis Gitsas", "George Floudas" ], "corpus_id": 97232650, "doc_id": "97232650", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Role of main chain rigidity and side chain substitution on the supramolecular organization of rigid flexible polymers", "venue": "", "year": 2006 }, { "abstract": "The glass transition temperature (Tg) of polymers is an important parameter that determines the kinetics of molecular organization of polymeric chains. Understanding the Tg of conjugated polymers i.", "author_names": [ "Anirudh Sharma", "Xun Pan", "Jonas Mattiasson Bjuggren", "Desta Gedefaw", "Xiaofeng Xu", "Renee Kroon", "Ergang Wang", "Jonathan A Campbell", "David A Lewis", "Mats R Andersson" ], "corpus_id": 182437628, "doc_id": "182437628", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Probing the Relationship between Molecular Structures, Thermal Transitions, and Morphology in Polymer Semiconductors Using a Woven Glass Mesh Based DMTA Technique", "venue": "Chemistry of Materials", "year": 2019 }, { "abstract": "Abstract The relationship between the isotropization transition temperatures and the associated entropy changes of two series of side chain liquid crystalline polymers based on three different polymer backbones (polymethacrylate, polyacrylate and polymethylsiloxane) and 4 methoxy 4' hydroxy a methylstilbene and 4 hydroxy 4' methoxy a methylstilbene mesogenic side groups attached to the polymer backbone through different flexible spacers is discussed. In the case of polymers containing long flexible spacers, isotropization transition temperatures, which are mostly dictated by the side groups, are higher for polymers based on flexible backbones, suggesting that they provide the highest degree of order in the mesophase. Therefore, their mesophase should exhibit the lowest entropy and the highest entropy change of isotropization. However, experimentally determined entropy changes of isotropization, which refer to the overall degree of order of the polymer, present the highest values for polymers based on the most rigid backbone. Two different mechanisms of distortion of the random coil conformation of flexible and rigid polymer backbones are suggested to account for this contradictory result. A squeezed random coil conformation, which in the case of smectic polymers is confined between the smectic layers, is considered for flexible backbones. An extended chain conformation is considered for rigid backbones. The entropy associated with the squeezed random coil conformation is higher than that associated with the extended conformation, and therefore the overall order that results from the combination of backbone and the organization of the mesogenic side groups may explain the experimentally observed isotropization entropy changes. Polymers based on short flexible spacers exhibit similar entropy changes of isotropization irrespective of the nature of their backbone. This may suggest an extended backbone conformation for polymers based on short spacers and rigid or flexible backbones.", "author_names": [ "Virgil Percec", "Dimitris Tomazos" ], "corpus_id": 95716652, "doc_id": "95716652", "n_citations": 24, "n_key_citations": 0, "score": 0, "title": "Can the rigidity of a side chain liquid crystalline polymer backbone influence the mechanism of distortion of its random coil conformation?", "venue": "", "year": 1990 }, { "abstract": "Shape persistent macrocycles based on the phenylene ethynylene butadiynylene backbone with extraannular amino groups were synthesized by the oxidative dimerization of the corresponding (BOC protected) half ring bisacetylenes. ABA block structures with a central rigid macrocycle and a flexible periphery (oligoalkyl and oligostyryl groups) were subsequently obtained by carbodiimide directed coupling of the macrocyclic diamines with the corresponding carboxylic acids. Depending on the solvent, an aggregation of the compounds toward tubular supramolecular polymer brushes could be induced. Cryogenic transmission electron microscopy and small angle neutron scattering reveal the tubelike aggregates in solution. Atomic force microscopy confirms the morphology of these aggregates after casting onto surfaces. The aggregate growth occurs remarkably slowly. Solvophobic interactions good solubility of the flexible substituents and weak solubility of the rigid macrocycle combined with the oblate shape of the latter are.", "author_names": [ "Martina Fritzsche", "Stefan-S Jester", "Sigurd Hoger", "Christina Klaus", "Nico Dingenouts", "Peter Linder", "Markus Drechsler", "Sabine Rosenfeldt" ], "corpus_id": 94309932, "doc_id": "94309932", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Self Organization of Coil Ring Coil Structures into Tubular Supramolecular Polymer Brushes: Synthesis, Morphology, and Growth", "venue": "", "year": 2010 }, { "abstract": "The ability to widely tune the design of macromolecular bottlebrushes provides access to self assembled nanostructures formed by microphase segregation in melt, thin film and solution that depart from structures adopted by simple linear copolymers. A series of random bottlebrush copolymers containing poly(3 hexylthiophene) (P3HT) and poly(d,l lactide) (PLA) side chains grafted on a poly(norbornene) backbone were synthesized via ring opening metathesis polymerization (ROMP) using the grafting through approach. P3HT side chains induce a physical aggregation of the bottlebrush copolymers upon solvent removal by vacuum drying, primarily driven by attractive p p interactions; however, the amount of aggregation can be controlled by adjusting side chain composition or by adding linear P3HT chains to the bottlebrush copolymers. Coarse grained molecular dynamics simulations reveal that linear P3HT chains preferentially associate with P3HT side chains of bottlebrush copolymers, which tends to reduce the aggregation. The nanoscale morphology of microphase segregated thin films created by casting P3HT PLA random bottlebrush copolymers is highly dependent on the composition of P3HT and PLA side chains, while domain spacing of nanostructures is mainly determined by the length of the side chains. The selective removal of PLA side chains under alkaline conditions generates nanoporous P3HT structures that can be tuned by manipulating molecular design of the bottlebrush scaffold, which is affected by molecular weight and grafting density of the side chains, and their sequence. The ability to exploit the unusual architecture of bottlebrushes to fabricate tunable nanoporous P3HT thin film structures may be a useful way to design templates for optoelectronic applications or membranes for separations.", "author_names": [ "Suk-Kyun Ahn", "Jan Michael Carrillo", "Jong K Keum", "Jihua Chen", "David M Uhrig", "Bradley S Lokitz", "Bobby G Sumpter", "S Michael Kilbey" ], "corpus_id": 206096312, "doc_id": "206096312", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Nanoporous poly(3 hexylthiophene) thin film structures from self organization of a tunable molecular bottlebrush scaffold.", "venue": "Nanoscale", "year": 2017 }, { "abstract": "A series of methacrylate based side chain liquid crystal polymers have been prepared with a range of molecular weight. For the high molecular weight polymers, a smectic phase is observed with a very narrow nematic range. However at low molecular weight only the nematic phase is observed. A marked reduction in Tg, Tsn and Tnias a function of reducing the molecular weight have been observed. Infrared dichroism measurements have been made to determine the order parameters of the liquid crystalline side chain polymers. It is found that the higher the molecular weight of the polymer the higher is the threshold voltage of the electro optic response, and the lower the order parameter. The increase in the threshold voltage with increasing molecular weight may be related to the intrinsic curvature elasticity and hence to the coupling between mesogenic units and the polymer backbone. Introduction:The design principles of side chain liquid crystal polymers are well established [1] These molecular composites consist of a flexible polymer backbone and a rigid mesogenic unit, joined as a side chain to the polymer backbone by means of a flexible coupling chain .Although there were initial suggestions that the spacer chain would decouple the motion of the mesogenic unit from the polymer backbone it is now clear that the relatively short length of the coupling chains will result in some interaction between the mesogenic units and the polymer backbone chains. The theoretical predictions of Warner et al [2,3] and others [4] have been substantiated by a number of neutron scattering studies [5,10] In the nematic phase, the coupling in systems based upon methacrylates appears to be negative in the sense that the polymer chains lie preferentially perpendicular to the mesogenic units [5,10] in contrast to the parallel arrangement in a crylate based backbones [7] for the smectic phase, the density of the layered structure of the mesogenic units acts to confine the polymer chain to a layer perpendicular to the mesogenic units [5,6,8,10] although there is some possibility of interlayet hopping by the polymer chain [11] By suitable chemical design, polymers can be synthesized that will exhibit [12,13] The well known electric and magnetic filed effects displayed by low molar mass counterparts [14] In such electro optic effects, what is the role of the polymer backbone? It is clear that the polymetric nature of the liquid crystal phase strongly effects the response times through a highly temperature dependent viscosity. Furthermore the electro optic response of a side chain liquid crystal polymer is particularly sensitive to the thermal history of each sample, and this may be related to the coupling of the side chain organization to the very long relaxation time of the polymer backbone [15] In this contribution we focus on the role of the polymer backbone in determining the static properties of the liquid crystal phase. In particular we want to give attention on the influence of the molecular weight upon curvature elasticity, which determines the case with which the director pattern may be modified using external electric fields. We shall consider a dd`l 1 @ljm @ybrtl @ylk @yssl' lbb `mj a b 0229 m @yssl' @ybrtl @ylkl ynthl ywnsl yml`l rmtw'ml /Skh dd` 5 5 0222 m 433 series of methacrylate based side chain liquid crystal homopolymers in which the molecular weight is systematically varied. The state of orientational order in these homopolymers is evaluated through the use of infra red spectroscopy which selectively probes only the mesogenic side chains. Carefully programmed electro optic measurements are used to evaluate the relationships between the variation in molecular weight, orientational order and electro optical properties. Materials:A series of methacrylate based side chain liquid crystalline homopolymers of the repeat unit shown have been prepared by free radical polymerization [16] The standard conditions used, (initiation by AIBN in chlorobenzene at 55C) have been modified to give a range of molecular weight by increasing the initiator concentration and by the addition of various amounts of dodecanethiol [17] as a chain transfer agent [18] Both of these modifications reduce the molecular weight of the polymer produced. The homopolymers are characterized by a smectic phase, identified as sceectic A by Davideon et. al. [19] over the greater part of the liquid crystal range. A nematic phase is seen over a narrow temperature range close to the clearing point. On reducing the molecular weight all of the phase transitions, Tg TSN and TNI are depressed (table 1) as has been seen for polyacrylate and polysiloxane based side chain liquid crystalline polymer systems [20,21] At low molecular weights however, (polymer 4 and 5) the smectic to nematic transition is no longer observed by DSC and no textural features characteristic of smectic phases can be observed by polarizing microscopy. This itself is not conclusive proof of the absence of a smectic phase since those materials which do exhibit textures identifiable as smectic only do so when annealed well below the apparent S N transition (as determined by DSC) Annealing of polymer samples 4 and 5 at temperatures well below TNI did not yield textures characteristic of the smectic phase. dd`l 1 @ljm @ybrtl @ylk @yssl' lbb `mj a b 0229 m @yssl' @ybrtl @ylkl ynthl ywnsl yml`l rmtw'ml /Skh dd` 5 5 0222 m 434 Table 1 Molecular weight and Phase Transition Data 2 no phase transition observed When interpreting the phase behaviour of these materials we have to be cautious in attributing effects solely to differences in molecular weight: in the lowest molecular weight members of this series a significant percentage of end groups will be chain transfer agent fragments, consisting of a long alkyl chain bound through a sulphur atom. This percentage has been determined by micro analysis for the sulphur content of the polymers [16] and has been found to be 20% for 5 and 14% for 4 In order to ascertain whether the plasticizing effect of the dodecyl chains is responsible for the anomalous phase behaviour, we prepared a series of copolymers of the liquid crystalline monomer and dodecyl methacrylate, under conditions similar to that of polymer 2. These materials showed similar phase behaviour to the homopolymers, in terms of detectable smectic to nematic and nematic to isotropic phase transitions, even when up to 15 mol% of the non mesogenic monomer was incorporated. The molecular weight data were determined by G.P.C. (RAPRA Ltd) at room temperature in tetraphydrofuran, using a combination of concentration and viscosity detectors and UNICAL universal calibrattion software. Experimental Methods:An electro optic experiment involves the measurement of changes in the optical properties of thin films of the liquid crystal polymers induced through the application of electric fields. The experimental arrangment used for these electro optic measurements has been described previously in detail elsewhere [15,22) The electro optic cell (described below) was held inside a temperature controlled stage providing a uniform temperature environment with functions of 0.25C. the optical system w n g SN NI dd`l 1 @ljm @ybrtl @ylk @yssl' lbb `mj a b 0229 m @yssl' @ybrtl @ylkl ynthl ywnsl yml`l rmtw'ml /Skh dd` 5 5 0222 m 435 consisted on a 5mW helium neon laser with crossed polarizer and analyzer system and a photodiode with amplifier for intensity measurements. Electric fields were provided by means of a power amplifier (Hewlett packard 6827 A) driven by a function generator (Thandar TG 501) this arrangement provided waveforms in the frequency range 0.05 to 30 KHz with peak to peak voltages in the range 0 to 240 volts. The intensity of the transmitted light through this optical system was recorded as a function of time using a microcomputer system based around a IBM compatible PC. Through the use of a specially written software system EOCS, sophisticated electrooptical experiments could be performed on a continuous or cyclic basis, involving temperature control, data recording, field switching and analysis [15] the electro optic cells with predefined director orientation were constructed from patterned tin oxide coated glass slides. After cleaning in an ultrasonic bath and drying, the cell electrodes were coated with a thin layer of a polyimide precursor consisting of a 5% solution of Rodehftal 322 in dimethylformamide using a spin coater. These coated slides were heated and tabbed in a single direction with a cloth. A small portion of the selected polymer sample was carefully applied onto one of the treated glass electrodes, which was then heated above its cleaning point in order to allow the trapped air to escape. The second glass electrode was then mounted above the first electrode using 0.025 mm thickness Kapton sheet as spacers. The quality of the direction orientation was confirmed through examination with a polarizing microscope. Complete and uniform director alignment was obtained by holding the completed electro optic cell at a temperature 1C below the measured clearing point for 15 hours. This technique was successful in inducing a uniform director alignment in electro optic cells for all the materials used in this work, in all cases, the predefined director alignment was parallel to the electrode surface and to the direction of rubbing. Some cells showed small numbers of defects such as small loops when examined using the polarizing microscope, however these largely disappeared after holding the cells at elevated temperatures. The orientational order parameter \"S\" for each polymer sample at a variety of temperatures was measured using infra red dichrosim employing a perkin Elmer 580B spectrometer fitted with a wire grid polarizer and heating stage [22] the order parameter measurements were made using monodom", "author_names": [ "A Khalkaf", "Khawaja Sabir Hassain", "A Abbas" ], "corpus_id": 208196142, "doc_id": "208196142", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "he Effect Of The Molecular Weight On The Static Electro Optic Properties Of Methacrylate Based Side Chain Liquid Polymers", "venue": "", "year": 2013 } ]

[ { "abstract": "The Technical Committee of the IEEE Magnetics Society has selected seven research topics to develop their roadmaps, where major developments should be listed alongside expected timelines: 1) hard disk drives; 2) magnetic random access memories; 3) domain wall devices; 4) permanent magnets; 5) sensors and actuators; 6) magnetic materials; and 7) organic devices. Among them, magnetic materials for spintronic devices have been surveyed as the first exercise. In this roadmap exercise, we have targeted magnetic tunnel and spin valve junctions as spintronic devices. These can be used, for example, as a cell for a magnetic random access memory and a spin torque oscillator in their vertical form as well as a spin transistor and a spin Hall device in their lateral form. In these devices, the critical role of magnetic materials is to inject spin polarized electrons efficiently into a nonmagnet. We have accordingly identified two key properties to be achieved by developing new magnetic materials for future spintronic devices: 1) half metallicity at room temperature (RT) and 2) perpendicular anisotropy in nanoscale devices at RT. For the first property, five major magnetic materials are selected for their evaluation for future magnetic/spintronic device applications: 1) Heusler alloys; 2) ferrites; 3) rutiles; 4) perovskites; and 5) dilute magnetic semiconductors. These alloys have been reported or predicted to be half metallic ferromagnets at RT. They possess a bandgap at the Fermi level EF only for its minority spins, achieving 100% spin polarization at EF. We have also evaluated L10 alloys and D022 Mn alloys for the development of a perpendicularly anisotropic ferromagnet with large spin polarization. We have listed several key milestones for each material on their functionality improvements, property achievements, device implementations, and interdisciplinary applications within 35 years time scale. The individual analyses and the projections are discussed in the following sections.", "author_names": [ "Atsufumi Hirohata", "Hiroaki Sukegawa", "Hideto Yanagihara", "Igor Zutic", "Takeshi Seki", "Shigemi Mizukami", "Rajasekaran Swaminathan" ], "corpus_id": 24710770, "doc_id": "24710770", "n_citations": 125, "n_key_citations": 1, "score": 1, "title": "Roadmap for Emerging Materials for Spintronic Device Applications", "venue": "IEEE Transactions on Magnetics", "year": 2015 }, { "abstract": "Spin orbit torque (SOT) is an emerging technology that enables the efficient manipulation of spintronic devices. The initial processes of interest in SOTs involved electric fields, spin orbit coupling, conduction electron spins, and magnetization. More recently, interest has grown to include a variety of other processes that include phonons, magnons, or heat. Over the past decade, many materials have been explored to achieve a larger SOT efficiency. Recently, holistic design to maximize the performance of SOT devices has extended material research from a nonmagnetic layer to a magnetic layer. The rapid development of SOT has spurred a variety of SOT based applications. In this article, we first review the theories of SOTs by introducing the various mechanisms thought to generate or control SOTs, such as the spin Hall effect, the Rashba Edelstein effect, the orbital Hall effect, thermal gradients, magnons, and strain effects. Then, we discuss the materials that enable these effects, including metals, metallic alloys, topological insulators, 2 D materials, and complex oxides. We also discuss the important roles in SOT devices of different types of magnetic layers, such as magnetic insulators, antiferromagnets, and ferrimagnets. Afterward, we discuss device applications utilizing SOTs. We discuss and compare three and two terminal SOT magnetoresistive random access memories (MRAMs) we mention various schemes to eliminate the need for an external field. We provide technological application considerations for SOT MRAM and give perspectives on SOT based neuromorphic devices and circuits. In addition to SOT MRAM, we present SOT based spintronic terahertz generators, nano oscillators, and domain wall and skyrmion racetrack memories. This article aims to achieve a comprehensive review of SOT theory, materials, and applications, guiding future SOT development in both the academic and industrial sectors.", "author_names": [ "Qiming Shao", "Luqiao Liu", "Hyunsoo Yang", "Shunsuke Fukami", "Armin Razavi", "Hao Wu", "Kang L Wang", "Frank Freimuth", "Yuriy Mokrousov", "Mark D Stiles", "Satoru Emori", "Axel Hoffmann", "Johan Akerman", "Kaushik Roy", "Jian-Ping Wang", "See-hun Yang", "Kevin Garello" ], "corpus_id": 233388176, "doc_id": "233388176", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Roadmap of Spin Orbit Torques", "venue": "IEEE Transactions on Magnetics", "year": 2021 }, { "abstract": "Part I. Advanced Flash and Nano Floating Gate Memories: 1. Scaling challenges for NAND and replacement memory technology Kirk Prall 2. Growth and in line characterization of silicon nanodots integrated in discrete charge trapping non volatile memories Julien Amouroux 3. Matrix density effect on morphology of germanium nanocrystals embedded in silicon dioxide thin films Arif Alagoz 4. Temperature effects on charge transfer mechanisms of nc ITO embedded ZrHfO high k nonvolatile memory devices Yue Kuo 5. Enhancement of nonvolatile floating gate memory devices containing AgInSbTe SiO2 nanocomposite by inserting HfO2/SiO2 blocking oxide layer Tsung Eong Hsieh Part II. Resistive Switching Memories: 6. Complementary resistive switches (CRS) high speed performance for the application in passive nanocrossbar arrays Roland Rosezin 7. Influence of copper on the switching properties of hafnium oxide based resistive memory Benjamin Briggs 8. Fabrication and characterization of copper oxide resistive memory devices Seann Bishop 9. Influence of process parameters on resistive switching in MOCVD NiO films Dirk Wouters 10. Understanding the role of process parameters on the characteristics of transition metal oxide RRAM/memristor devices Rashmi Jha 11. Memristive switches with two switching polarities in a forming free device structure Rainer Bruchhaus 12. WOx resistive memory elements for scaled flash memories Judit G. Lisoni 13. Memory retention characteristics of data storage area written in transition metal oxide films by using atomic force microscope Kentaro Kinoshita 14. A survey of metal oxides and top electrodes for resistive memory devices Seann Bishop 15. Switching speed in resistive random access memories (RRAMs) based on plastic semiconductor Paulo Rocha 16. Retentivity of RRAM devices based on metal/YBCO interfaces Carlos Acha 17. Electro forming of vacancy doped metal SrTiO3 metal structures Barbara Abendroth Part III. Phase Change, Ferroelectric, and Organic Memories: 18. Interface characterization of metals and metal nitrides to phase change materials Deepu Roy 19. Investigation on phase change behaviors of Si Sb Te alloy: the effect of tellurium segregation Xilin Zhou 20. Recent progress in downsizing FeFETs for Fe NAND application Shigeki Sakai 21. Lanthanum oxide capping layer for solution processed ferroelectric gate thin film transistors Tue Phan 22. New MEH PPV based composite materials for rewritable nonvolatile polymer memory devices Mikhail Dronov 23. Planar non volatile memory based on metal nanoparticles Asal Kiazadeh.", "author_names": [ "Dirk J Wouters", "Physics for Non-Volatile Memories", "Process for Non-Volatile Memories" ], "corpus_id": 135588875, "doc_id": "135588875", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "New functional materials and emerging device architectures for nonvolatile memories symposium held April 25 29, 2011, San Francisco, California, U.S.A.", "venue": "", "year": 2011 }, { "abstract": "Author(s) Sander, D; Valenzuela, SO; Makarov, D; Marrows, CH; Fullerton, EE; Fischer, P; McCord, J; Vavassori, P; Mangin, S; Pirro, P; Hillebrands, B; Kent, AD; Jungwirth, T; Gutfleisch, O; Kim, CG; Berger, A Abstract: (c) 2017 IOP Publishing Ltd. Building upon the success and relevance of the 2014 Magnetism Roadmap, this 2017 Magnetism Roadmap edition follows a similar general layout, even if its focus is naturally shifted, and a different group of experts and, thus, viewpoints are being collected and presented. More importantly, key developments have changed the research landscape in very relevant ways, so that a novel view onto some of the most crucial developments is warranted, and thus, this 2017 Magnetism Roadmap article is a timely endeavour. The change in landscape is hereby not exclusively scientific, but also reflects the magnetism related industrial application portfolio. Specifically, Hard Disk Drive technology, which still dominates digital storage and will continue to do so for many years, if not decades, has now limited its footprint in the scientific and research community, whereas significantly growing interest in magnetism and magnetic materials in relation to energy applications is noticeable, and other technological fields are emerging as well. Also, more and more work is occurring in which complex topologies of magnetically ordered states are being explored, hereby aiming at a technological utilization of the very theoretical concepts that were recognised by the 2016 Nobel Prize in Physics. Given this somewhat shifted scenario, it seemed appropriate to select topics for this Roadmap article that represent the three core pillars of magnetism, namely magnetic materials, magnetic phenomena and associated characterization techniques, as well as applications of magnetism. While many of the contributions in this Roadmap have clearly overlapping relevance in all three fields, their relative focus is mostly associated to one of the three pillars. In this way, the interconnecting roles of having suitable magnetic materials, understanding (and being able to characterize) the underlying physics of their behaviour and utilizing them for applications and devices is well illustrated, thus giving an accurate snapshot of the world of magnetism in 2017. The article consists of 14 sections, each written by an expert in the field and addressing a specific subject on two pages. Evidently, the depth at which each contribution can describe the subject matter is limited and a full review of their statuses, advances, challenges and perspectives cannot be fully accomplished. Also, magnetism, as a vibrant research field, is too diverse, so that a number of areas will not be adequately represented here, leaving space for further Roadmap editions in the future. However, this 2017 Magnetism Roadmap article can provide a frame that will enable the reader to judge where each subject and magnetism research field stands overall today and which directions it might take in the foreseeable future. The first material focused pillar of the 2017 Magnetism Roadmap contains five articles, which address the questions of atomic scale confinement, 2D, curved and topological magnetic materials, as well as materials exhibiting unconventional magnetic phase transitions. The second pillar also has five contributions, which are devoted to advances in magnetic characterization, magneto optics and magneto plasmonics, ultrafast magnetization dynamics and magnonic transport. The final and application focused pillar has four contributions, which present non volatile memory technology, antiferromagnetic spintronics, as well as magnet technology for energy and bio related applications. As a whole, the 2017 Magnetism Roadmap article, just as with its 2014 predecessor, is intended to act as a reference point and guideline for emerging research directions in modern magnetism.", "author_names": [ "Daniel J Sander", "Sergio O Valenzuela", "Denys Makarov", "Christopher H Marrows", "Eric E Fullerton", "Peter Fischer", "Jeffrey McCord", "Paolo Vavassori", "Stephane Mangin", "Philipp Pirro", "Burkard Hillebrands", "Andrew D Kent", "Tomas Jungwirth", "Oliver Gutfleisch", "Cheolgi Kim", "Andreas Berger" ], "corpus_id": 4810990, "doc_id": "4810990", "n_citations": 215, "n_key_citations": 1, "score": 0, "title": "The 2017 Magnetism Roadmap", "venue": "", "year": 2017 }, { "abstract": "Magnetism is a very fascinating and dynamic field. Especially in the last 30 years it has experienced many major advances in the full range from novel fundamental phenomena to new products. Applications such as hard disk drives and magnetic sensors are part of our daily life, and new applications, such as in non volatile computer random access memory, are expected to surface shortly. Thus it is timely for describing the current status, and current and future challenges in the form of a Roadmap article. This 2014 Magnetism Roadmap provides a view on several selected, currently very active innovative developments. It consists of 12 sections, each written by an expert in the field and addressing a specific subject, with strong emphasize on future potential. This Roadmap cannot cover the entire field. We have selected several highly relevant areas without attempting to provide a full review a future update will have room for more topics. The scope covers mostly nano magnetic phenomena and applications, where surfaces and interfaces provide additional functionality. New developments in fundamental topics such as interacting nano elements, novel magnon based spintronics concepts, spin orbit torques and spin caloric phenomena are addressed. New materials, such as organic magnetic materials and permanent magnets are covered. New applications are presented such as nano magnetic logic, non local and domain wall based devices, heat assisted magnetic recording, magnetic random access memory, and applications in biotechnology. May the Roadmap serve as a guideline for future emerging research directions in modern magnetism.", "author_names": [ "Robert Stamps", "Stephan Breitkreutz", "J Aakerman", "Andrii V Chumak", "Yoshichika Otani", "Gerrit E W Bauer", "Jan Ulrich Thiele", "Martin Bowen", "Sara A Majetich", "Mathias Klaui", "Ioan Lucian Prejbeanu", "Bernard Dieny", "Nora M Dempsey", "Burkard Hillebrands" ], "corpus_id": 119196613, "doc_id": "119196613", "n_citations": 212, "n_key_citations": 0, "score": 0, "title": "The 2014 Magnetism Roadmap", "venue": "", "year": 2014 }, { "abstract": "Dilute magnetic semiconductors (DMSs) attract tremendous interest as emerging candidates for the microelectronics industry due to their uniqueness in exhibiting spin dependent magneto electro optical properties. Their distinctive material characteristics such as spin dependent coupling between semiconductor bands and the localized states promises magnetoelectric effect the modulation of magnetic properties by an applied electric field in semiconductors (Kulkarni et al. 2005, Ohno et al. 2000) Thus, a wide variety of semiconductor devices can be envisaged (Brunner, 2002a) such as spin polarized lightemitting diodes, lasers (Schulthess and Butler, 2001, Schilfgaarde and Mryasov, 2001) and spin transistor logic devices (Chen et al. 2005, Brunner, 2002b, Ohno et al. 2000) The development of these devices is considered as a possible route for extending the semiconductor scaling roadmap to spin added electronics (Liu et al. 2005)", "author_names": [ "Faxian Xiu", "Jin Zou", "Kang L Wang" ], "corpus_id": 208541741, "doc_id": "208541741", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Magnetic MnxGe1 x Dots for Spintronics Applications", "venue": "", "year": 2018 }, { "abstract": "Two dimensional (2D) hexagonal boron nitride (h BN) is one of the most promising materials for many technological applications ranging from optics to electronics. In past years, a property tunable strategy that involves the construction of electronic structures of h BN through an atomic level design of point defects has been in vogue. The point defects imported during material synthesis or functionalization by defect engineering can endow h BN with new physical characteristics and applications. In this Perspective, we survey the current state of the art in multifunction variations induced by point defects for 2D h BN. We begin with an introduction of the band structure and electronic property of the pristine h BN. Subsequently, the formation and characterization of the most obvious point defects and their modulation in electronic structures of h BN nanomaterials are envisaged in theory. The experimental results obtained by atom resolved transmission electron microscopy, magnetic measurement, and optical measurements have provided insights into the point defect engineered structures and their corresponding emerging properties. Finally, we highlight the perspectives of h BN nanomaterials for heterostructures and devices. This Perspective provides a landscape of the point defect physics involved to demonstrate the modulation of the structure and functionalities in h BN and identify the roadmap for heterostructure and device applications, which will make advances in electronics, spintronics, and nanophotonics.", "author_names": [ "Jijun Zhang", "Dongliang Ruan", "Yanxi Li" ], "corpus_id": 225274624, "doc_id": "225274624", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Point defects in two dimensional hexagonal boron nitride: A perspective", "venue": "", "year": 2020 }, { "abstract": "Molecular/inorganic multilayer heterostructures are gaining attention in molecular electronics and more recently in new generation spintronic devices. The intrinsic properties of molecular materials as low cost, tuneability, or long spin lifetimes were the original reasons behind their implementation. However, the non innocent role played by these hybrid interfaces is a determinant factor in the device performance. In this account we will give an overview about different types of hybrid molecular system/ferromagnet interfaces, which can be of direct application in molecular spintronics. This includes the insertion of a 2D material in between the molecular system and the ferromagnet. As perspective, new hybrid interfaces able to tune the spin properties under an external stimulus, are proposed. These smart interfaces, based on switchable magnetic molecules or flexible MOFs, can open the way to new multifunctional spintronic devices able to couple the spin with a second property.", "author_names": [ "Alicia Forment-Aliaga", "Eugenio Coronado" ], "corpus_id": 3710895, "doc_id": "3710895", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Hybrid Interfaces in Molecular Spintronics.", "venue": "Chemical record", "year": 2018 }, { "abstract": "Skyrmionic textures are being extensively investigated due to the occurrence of novel topological magnetic phenomena and their promising applications in a new generation of spintronic devices that take advantage of the robust topological stability of their spin structures. The development of practical devices relies on a detailed understanding of how skyrmionic structures can be formed, transferred, detected and annihilated. In this work, our considerations go beyond static skyrmions and theoretically show that the formation/annihilation of both skyrmions and antiskyrmions is enabled by the transient creation and propagation of topological singularities (magnetic monopole like Bloch points) Critically, during the winding/unwinding of skyrmionic textures, our results predict that the Bloch point propagation will give rise to an emergent electric field in a terahertz frequency range and with substantial amplitude. We also demonstrate ways for controlling Bloch point dynamics, which directly enable the tuneability on both frequency and amplitude of this signal. Our studies provide a concept of directly exploiting topological singularities for terahertz skyrmion based electronic devices.", "author_names": [ "Yu Li", "Leonardo Pierobon", "Michalis Charilaou", "H B Braun", "Niels R Walet", "Jorg F Loffler", "Jim J Miles", "Christoforos Moutafis" ], "corpus_id": 208513334, "doc_id": "208513334", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "Tunable terahertz oscillation arising from Bloch point dynamics in chiral magnets", "venue": "", "year": 2019 }, { "abstract": "(La,Sr)MnO(3) manganite (LSMO) has emerged as the standard ferromagnetic electrode in organic spintronic devices due to its highly spin polarized character and air stability. Whereas organic semiconductors and polymers have been mainly envisaged to propagate spin information, self assembled monolayers (SAMs) have been overlooked and should be considered as promising materials for molecular engineering of spintronic devices. Surprisingly, up to now the first key step of SAM grafting protocols over LSMO surface thin films is still missing. We report the grafting of dodecyl (C12P) and octadecyl (C18P) phosphonic acids over the LSMO half metallic oxide. Alkylphosphonic acids form ordered self assembled monolayers, with the phosphonic group coordinated to the surface and alkyl chains tilted from the surface vertical by 43deg (C12P) and 27deg (C18P) We have electrically characterized these SAMs in nanodevices and found that they act as tunnel barriers, opening the door toward the integration of alkylphosphonic acid//LSMO SAMs into future molecular/organic spintronic devices such as spin OLEDs.", "author_names": [ "Sergio Tatay", "Clement Barraud", "Marta Galbiati", "Pierre Seneor", "Richard Mattana", "Karim Bouzehouane", "Cyrile Deranlot", "Eric Jacquet", "Alicia Forment-Aliaga", "Pascale Jegou", "Albert Fert", "Fr'ed'eric Petroff" ], "corpus_id": 5169876, "doc_id": "5169876", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "Self assembled monolayer functionalized half metallic manganite for molecular spintronics.", "venue": "ACS nano", "year": 2012 } ]

[ { "abstract": "Background The photolithography process in the semiconductor industry uses various chemicals with little information on their constitution. This study aimed to identify the chemical constituents of photoresist (PR) products and their by products and to compare these constituents with material safety data sheets (MSDSs) and analytical results. Methods A total of 51 PRs with 48 MSDSs were collected. Analysis consisted of two parts: First, the constituents of the chemical products were identified and analyzed using MSDS data; second, for verification of the by products of PR, volatile organic compounds were analyzed. The chemical constituents were categorized according to hazards. Results Forty five of 48 products contained trade secrets in amounts ranging from 1 to 65% A total of 238 ingredients with multiple counting (35 ingredients without multiple counting) were identified in the MSDS data, and 48.7% of ingredients were labeled as trade secrets under the Korea Occupational Safety and Health Act. The concordance rate between the MSDS data and the analytical result was 41.7% The by product analysis identified 129 chemicals classified according to Chemical Abstracts Service No. with 17 chemicals that are carcinogenic, mutagenic, and reprotoxic substances. Formaldehyde was found to be released from 12 of 21 products that use novolak resin. Conclusion We confirmed that several PRs contain carcinogens, and some were not specified in the toxicological information in the MSDS. Hazardous chemicals, including benzene and formaldehyde, are released from PRs products as by products. Therefore, it is necessary to establish a systematic management system for chemical compounds and the working environment.", "author_names": [ "Miyeon Jang", "Chungsik Yoon", "Jihoon Park", "Ohhun Kwon" ], "corpus_id": 93003318, "doc_id": "93003318", "n_citations": 8, "n_key_citations": 1, "score": 1, "title": "Evaluation of Hazardous Chemicals with Material Safety Data Sheet and By products of a Photoresist Used in the Semiconductor Manufacturing Industry", "venue": "Safety and health at work", "year": 2019 }, { "abstract": "The purpose of this study was to investigate the furnishing rate and dental technicians' comprehension level on Material Safety Data Sheet (MSDS) in Jeju province. On line and off line questionnaires filled out by 102 dental technicians were acquired and analyzed by frequency analysis, chi squared test, and one way ANOVA by SPSS 20.0. On average, respondents rated 3.21+ 0.87 on a Likert 5 point scale regarding familiarity with hazardous effects of chemicals, 2.54+ 1.09 to awareness of MSDS, and 2.05+ 1.09 to familiarity with the contents of MSDS. Regarding availability of MSDS or similar information at workplace, 18.6% responded MSDS were furnished, 5.9% responded similar information sheets were provided, 29.4% responded MSDS or similar information sheets were not furnished, and 46.1% responded that they were not sure. Total of 24.5% responded positive to availability of MSDS or similar information, which was higher than result from a similar study from 2010 but lower than that of the 2016 study. Gender difference in awareness and comprehension level of MSDS were noted. No statistically significant differences were noted between graduates of Jeju and of other regions regarding awareness and comprehension of MSDS. Position at work rather than length of employment affected level of awareness and comprehension of MSDS. Efforts to rouse dental technicians' interest in chemical safety may enhance workplace health and safety, and there is room for improvement in MSDS provision and education in dental labs of Jeju.", "author_names": [ "Jae-Man Woo", "Chan Woo Jo", "Se Hoon Kahm", "Gyeong Pil Moon", "Jung Kwan Eun", "Sung-Joon Kim" ], "corpus_id": 117269466, "doc_id": "117269466", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Awareness and assessment of the Material Safety Data Sheet by dental technicians in Jeju province", "venue": "", "year": 2018 }, { "abstract": "Abstrak Penelitian ini bertujuan untuk mengembangkan buku petunjuk praktikum kimia anorganik yang disertai dengan Material Data Sheet. Untuk mengetahui kevalidan, kepraktisan, dan keefektifan dari buku petunjuk praktikum yang dikembangkan, maka dilakukan penelitian pengembangan mengacu pada R D yang dikemukakan oleh Plomp (2010) Data hasil penelitian dianalisis menggunakan statistik deskriptif. Dari hasil analisis diperoleh beberapa temuan sebagai berikut: (1) buku petunjuk praktikum yang dikembangkan telah valid ditinjau dari kriteria isi, kriteria kebahasaan, kriteria penyajian, dan kriteria kegrafikan; (2) buku petunjuk praktikum yang dikembangkan telah praktis ditinjau dari angket respon mahasiswa dan hasil observasi aktivitas mahasiswa; (3) buku petunjuk praktikum yang dikembangkan telah efektif ditinjau dari hasil belajar mahasiswa. Kata kunci: pengembangan, buku petunjuk praktikum, Material Safety Data Sheet. Abstract The purpose of this research is to develop experimental guidance book for inorganic chemistry with material safety data sheet. Design of development experimental guidance book was R D by Plomp (2010) Data of the research was analyzed by descriptive statistic. The result of the research were: (1) the experimental guidance book in developing are good in content validity, language validity, presentation validity, and graphic validity; (2) the experimental guidancw book in developing are practice based on university students response and university students activity; (3) the experimental guidance book in developing are efective based on learning outcome. Keywords: development, experimental guidance book, Material Safety Data Sheet", "author_names": [ "Rusly Hidayah", "Dina Kartika Maharani" ], "corpus_id": 133086562, "doc_id": "133086562", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "PENGEMBANGAN BUKU PETUNJUK PRAKTIKUM KIMIA ANORGANIK YANG DISERTAI DENGAN MATERIAL SAFETY DATA SHEET", "venue": "", "year": 2018 }, { "abstract": "Kimia merupakan bidang yang tidak terlepas dari kegiatan riset. Para pelaku riset sangatlah wajib dalam memperhatikan aspek kesehatan dan keselamatan. Untuk itu diperlukan pengetahuan dan pengenalan aspek aspek yang terkait pada suatu bahan kimia. Sehingga dengan dibangunnya aplikasi ini diharapkan akan menunjang kinerja dan meminimalkan potensi kecelakaan kerja para pelaku riset diantaranya teknisi laboratorium, analis kimia, mahasiswa kimia maupun dosen kimia. Algoritma Boyer Moore merupakan metode pencarian pattern di dalam teks, Algoritma Boyer Moore dianggap sebagai algoritma pencocokan string yang efisien sehingga dalam pencarian bahan kimia dengan menggunakan aplikasi pengetahuan umum sifat fisik bahan kimia serta Material Safety Data Sheet (MSDS) Laboratorium menjadi lebih mudah dan cepat. Speech to text merupakan proses mengkonversi input suara menjadi output digital atau teks. Dengan fitur mendengarkan suara pengguna, memahaminya dan mengubahnya ke dalam bentuk output yang diinginkan dan juga melakukan tindakan yang dibutuhkan agar dapat mempermudah pengguna dalam melakukan pencarian. Chemistry is a field that cannot be separated from research activities. Researchers are obliged to pay attention to health and safety aspects. For this reason, knowledge and an introduction to the related aspects of a chemical are needed. So that the construction of this application is expected to support performance and minimize the potential for workplace accidents, including laboratory technicians, chemical analysts, chemical students and chemistry lecturers. Boyer Moore algorithm is a method of searching patterns in the text, Boyer Moore Algorithm is considered as an efficient string matching algorithm so that in the search for chemicals by using applications of general knowledge of the physical properties of chemicals and Material Safety Data Sheet (MSDS) the Laboratory becomes easier and fast. Speech to text is the process of converting voice input into digital output or text. The feature listens to the user's voice, understands it and converts it into the desired output form and also takes the actions needed to make it easier for users to search.", "author_names": [ "Abdul Aziz Aminudin" ], "corpus_id": 186825052, "doc_id": "186825052", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Aplikasi pengetahuan umum sifat fisik bahan kimia serta MSDS (Material Safety Data Sheet)Laboratorium menggunakan algoritma boyer moore berbasis android", "venue": "", "year": 2018 }, { "abstract": "", "author_names": [ "Sangjun Choi", "Youngeun Choi", "Jeongim Park", "" ], "corpus_id": 181352543, "doc_id": "181352543", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Improvement of Material Safety Data Sheet Regulation for Enhancing the Effectiveness and Efficiency in the Field", "venue": "", "year": 2018 }, { "abstract": "", "author_names": [ "Hong-Kwan Kim", "Youngwoo Chon", "Kwang-Hoon Ko", "Yongwoo Hwang", "Jung-Soo Kim", "Ik Mo Lee" ], "corpus_id": 198487232, "doc_id": "198487232", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A Study on the Awareness of Material Safety Data Sheet (MSDS) of University Laboratory Workers", "venue": "", "year": 2018 }, { "abstract": "Because of the vertical combustion characteristics of combustible substances, accurate substance safety information for their safe use, handling and transportation is essential. The flash point, fire point, explosion limits and autoignition temperature (AIT) are important safety parameters which need special attention in chemical plants and laboratories that handle dangerous materials. In this study, tert butylbenzene which is widely used as an intermediate material in the chemical industry was selected. For the reliability of the flammable properties of tert butylbenzene, this study was investigated the explosion limits of tert butylbenzene in the reference data. The flash points, fire points and AITs by the ignition delay time for tert butylbenzene were experimented. The lower flash points of tert butylbenzene by using the Setaflash and Pensky Martens closed cup testers measured 39 degC and 44 degC, respectively. The flash points of tert butylbenzene by using the Tag and Cleveland open cup testers are measured 51 degC and 54 degC. And the fire points of tert butylbenzene by the Tag and Cleveland open cup testers were 54 degC and 58 degC respectively. The AIT of tert butylbenzene measured by the ASTM 659E tester was measured as 450 degC. The lower explosion limit of 39 degC which measured by the Setaflash flash point tester was calculated to be 0.68 vol%", "author_names": [ "Dong-Myeong Ha" ], "corpus_id": 139583273, "doc_id": "139583273", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "The Measurement of the Combustible Properties of tert Butylbenzene for the Improvement of MSDS(Material Safety Data Sheet)", "venue": "", "year": 2017 }, { "abstract": "J. Anderson et al. \"Farm Program Helps Japanese, San Antonio Express News, Jun. 9, 1993. J. Anderson et al. \"USDA Promoting New Uses for Farm Products' United Feature Syndicate, Jun. 9, 1993. A. Balden, \"Binders from Soy Flour' Chemical Abstracts, 106, No. 24, Abstract No. 198031, Jun. 5, 1987. A. Behling, \"Soybean Based Building Material Creates Excitement' Soybean Digest, p. 28, Aug./Sep. 1993.", "author_names": [ "Katharina Schulz" ], "corpus_id": 56129429, "doc_id": "56129429", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Honeymead Products Company Material Safety Data Sheet Product Name Soybean Flour Flakes", "venue": "", "year": 2017 }, { "abstract": "saeobjangeseo hwajae mic pogbaleul yebanghagi wihaeseoneun yeonsoteugseongciro inhwajeom, pogbalhangye, coesojayeonbalhwaondo deungeul deul su issda. hwahaggongjeongyi anjeoneul wihaeseo cwigeub muljilyi jeonghwaghan muljilbogeonanjeonjaryo(MSDS)yi yeonsoteugseongci sayongeun maeu jungyohada. hwahagsaneobeseo dayanghage sayongdoego issneun benjilalkoolyi anjeonhan cwigeubeul wihaeseo inhwajeomgwa coesojayeonbalhwaondoreul ceugjeonghayeossda. benjilalkoolyi pogbalhahangyeneun silheomeseo eodeojin habuinhwajeomeul iyonghayeo gyesanhayeossda. benjilalkoolyi Setaflash milpyesigeun 90 Pensky Martens milpyesigeseoneun 93 geurigo Tag gaebangsigeseoneun 97 Cleveland gaebangsigeseoneun 100 ro ceugjeongdoeeossda. ASTM E659 jangcie yihan ceugjeongdoen benjilalkoolyi coesojayeonbalhwaondoneun 408 ro ceugjeongdoeeossda. Setaflash milpyesige yihae ceugjeongdoen benjilalkoolyi habuinhwajeom 90 yi pogbalhahangyeneun 1.17 vol%ro gyesandoeeossda. bon yeongueseoneun Setaflash milpyesige yihae ceugjeongdoen benjilalkoolyi habuinhwajeomeul iyonghayeo pogbalhahangyeyi yeceugi ganeunghayeossda.", "author_names": [ "" ], "corpus_id": 99215322, "doc_id": "99215322", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "MSDS (Material Safety Data Sheet)reul wihan benjilalkool yeonsoteugseongciyi ceugjeong mic yeceug", "venue": "", "year": 2017 }, { "abstract": "", "author_names": [ "Hyung-Jun An", "Won-bae Tae", "Hyeon Oh", "Min Song", "C Park", "Eun-Jeong Bae" ], "corpus_id": 113934530, "doc_id": "113934530", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Recognition of the Material Safety Data Sheet of dental technicians Focused on Gyeonggi do Dental Technicians", "venue": "", "year": 2016 } ]

[ { "abstract": "An all silicon in plane micron size electrically driven resonant cavity light emitting device (RCLED) based on slotted waveguide is proposed and modeled. The device consists of a microring resonator formed by Si/SiO2 slot waveguide with a low index electroluminescent material (erbium doped SiO2) in the slot region. The geometry of the slot waveguide permits the definition of a metal oxide semiconductor (MOS) configuration for the electrical excitation of the active material. Simulations predict a quality factor Q of 6,700 for a 20 microm radius electrically driven microring RCLED capable to operate at a very low bias current of 0.75 nA. Lasing conditions are also discussed.", "author_names": [ "Carlos Angulo Barrios", "Michal Lipson" ], "corpus_id": 6466092, "doc_id": "6466092", "n_citations": 181, "n_key_citations": 1, "score": 1, "title": "Electrically driven silicon resonant light emitting device based on slot waveguide.", "venue": "Optics express", "year": 2005 }, { "abstract": "Silicon photonics could enable a chip scale platform for monolithic integration of optics and microelectronics for applications of optical interconnects in which high data streams are required in a small footprint. This paper discusses mechanisms in silicon photonics for waveguiding, modulating, light amplification, and emission. These mechanisms, together with recent advances of fabrication techniques, have enabled the demonstration of ultracompact passive and active silicon photonic components with very low loss.", "author_names": [ "Michal Lipson" ], "corpus_id": 42767475, "doc_id": "42767475", "n_citations": 678, "n_key_citations": 19, "score": 0, "title": "Guiding, modulating, and emitting light on Silicon challenges and opportunities", "venue": "Journal of Lightwave Technology", "year": 2005 }, { "abstract": "We examine the current performance and future demands of interconnects to and on silicon chips. We compare electrical and optical interconnects and project the requirements for optoelectronic and optical devices if optics is to solve the major problems of interconnects for future high performance silicon chips. Optics has potential benefits in interconnect density, energy, and timing. The necessity of low interconnect energy imposes low limits especially on the energy of the optical output devices, with a 10 fJ/bit device energy target emerging. Some optical modulators and radical laser approaches may meet this requirement. Low (e.g. a few femtofarads or less) photodetector capacitance is important. Very compact wavelength splitters are essential for connecting the information to fibers. Dense waveguides are necessary on chip or on boards for guided wave optical approaches, especially if very high clock rates or dense wavelength division multiplexing (WDM) is to be avoided. Free space optics potentially can handle the necessary bandwidths even without fast clocks or WDM. With such technology, however, optics may enable the continued scaling of interconnect capacity required by future chips.", "author_names": [ "David A B Miller" ], "corpus_id": 15772363, "doc_id": "15772363", "n_citations": 1770, "n_key_citations": 76, "score": 0, "title": "Device Requirements for Optical Interconnects to Silicon Chips", "venue": "Proceedings of the IEEE", "year": 2009 }, { "abstract": "A theoretical investigation of silicon on insulator nanometer slot waveguides for highly sensitive and compact chemical and biochemical integrated optical sensing is proposed. Slot guiding structures enabling high optical confinement in a low index very small region are demonstrated to be very sensitive to either cover medium refractive index change or deposited receptor layer thickness increase. Modal and confinement properties of slot waveguides have been investigated, considering also the influence of fabrication tolerances. Waveguide sensitivity has been calculated and compared with that exhibited by other silicon nanometer guiding structures, such as rib or wire waveguides, or with experimental values in literature.", "author_names": [ "Francesco Dell'Olio", "Vittorio M N Passaro" ], "corpus_id": 9372245, "doc_id": "9372245", "n_citations": 327, "n_key_citations": 8, "score": 0, "title": "Optical sensing by optimized silicon slot waveguides.", "venue": "Optics express", "year": 2007 }, { "abstract": "Integrated optical circuits based on silicon on insulator technology are likely to become the mainstay of the photonics industry. Over recent years an impressive range of silicon on insulator devices has been realized, including waveguides1,2, filters3,4 and photonic crystal devices5. However, silicon based all optical switching is still challenging owing to the slow dynamics of two photon generated free carriers. Here we show that silicon organic hybrid integration overcomes such intrinsic limitations by combining the best of two worlds, using mature CMOS processing to fabricate the waveguide, and molecular beam deposition to cover it with organic molecules that efficiently mediate all optical interaction without introducing significant absorption. We fabricate a 4 mm long silicon organic hybrid waveguide with a record nonlinearity coefficient of g 1 x 105 W 1 km 1 and perform all optical demultiplexing of 170.8 Gb s 1 to 42.7 Gb s 1. This is to the best of our knowledge the fastest silicon photonic optical signal processing demonstrated. A silicon organic hybrid slot waveguide with a strong optical nonlinearity is demonstrated to perform ultrafast all optical demultiplexing of high bit rate data streams. The approach could form the basis of compact high speed optical processing units for future communication networks.", "author_names": [ "Christian Koos", "P Vorreau", "T Vallaitis", "Pieter Dumon", "Wim Bogaerts", "Roel Baets", "Bweh Esembeson", "Ivan Biaggio", "Tsuyoshi Michinobu", "Francois Diederich", "Wolfgang Freude", "Juerg Leuthold" ], "corpus_id": 13125120, "doc_id": "13125120", "n_citations": 717, "n_key_citations": 18, "score": 0, "title": "All optical high speed signal processing with silicon organic hybrid slot waveguides", "venue": "", "year": 2009 }, { "abstract": "High index contrast, wavelength scale structures are key to ultracompact integration of photonic integrated circuits. The fabrication of these nanophotonic structures in silicon on insulator using complementary metal oxide semiconductor processing techniques, including deep ultraviolet lithography, was studied. It is concluded that this technology is capable of commercially manufacturing nanophotonic integrated circuits. The possibilities of photonic wires and photonic crystal waveguides for photonic integration are compared. It is shown that, with similar fabrication techniques, photonic wires perform at least an order of magnitude better than photonic crystal waveguides with respect to propagation losses. Measurements indicate propagation losses as low as 0.24 dB/mm for photonic wires but 7.5 dB/mm for photonic crystal waveguides.", "author_names": [ "Wim Bogaerts", "Roel Baets", "Pieter Dumon", "Vincent Wiaux", "S Beckx", "Dirk Taillaert", "Bert Luyssaert", "Joris Van Campenhout", "Peter Bienstman", "Dries van Thourhout" ], "corpus_id": 40896078, "doc_id": "40896078", "n_citations": 842, "n_key_citations": 27, "score": 0, "title": "Nanophotonic waveguides in silicon on insulator fabricated with CMOS technology", "venue": "Journal of Lightwave Technology", "year": 2005 }, { "abstract": "We present a computing microsystem that uniquely leverages the bandwidth, density, and latency advantages of silicon photonic interconnect to enable highly compact supercomputer scale systems. We describe and justify single node and multinode systems interconnected with wavelength routed optical links, quantify their benefits vis a vis electrically connected systems, analyze the constituent optical component and system requirements, and provide an overview of the critical technologies needed to fulfill this system vision. This vision calls for more than a hundredfold reduction in energy to communicate an optical bit of information. We explore the power dissipation of a photonic link, suggest a roadmap to lower the energy per bit of silicon photonic interconnects, and identify the challenges that will be faced by device and circuit designers towards this goal.", "author_names": [ "Ashok V Krishnamoorthy", "Ron Ho", "Xuezhe Zheng", "Herb Schwetman", "Jon K Lexau", "Pranay Koka", "Guoliang Li", "Ivan Shubin", "John E Cunningham" ], "corpus_id": 6173689, "doc_id": "6173689", "n_citations": 429, "n_key_citations": 23, "score": 0, "title": "Computer Systems Based on Silicon Photonic Interconnects", "venue": "Proceedings of the IEEE", "year": 2009 }, { "abstract": "It is known that light can be slowed down in dispersive materials near resonances. Dramatic reduction of the light group velocity and even bringing light pulses to a complete halt has been demonstrated recently in various atomic and solid state systems, where the material absorption is cancelled via quantum optical coherent effects. Exploitation of slow light phenomena has potential for applications ranging from all optical storage to all optical switching. Existing schemes, however, are restricted to the narrow frequency range of the material resonance, which limits the operation frequency, maximum data rate and storage capacity. Moreover, the implementation of external lasers, low pressures and/or low temperatures prevents miniaturization and hinders practical applications. Here we experimentally demonstrate an over 300 fold reduction of the group velocity on a silicon chip via an ultra compact photonic integrated circuit using low loss silicon photonic crystal waveguides that can support an optical mode with a submicrometre cross section. In addition, we show fast ~100 ns) and efficient (2 mW electric power) active control of the group velocity by localized heating of the photonic crystal waveguide with an integrated micro heater.", "author_names": [ "Yurii A Vlasov", "Martin P O'Boyle", "Hendrik F Hamann", "S Mcnab" ], "corpus_id": 4335328, "doc_id": "4335328", "n_citations": 1197, "n_key_citations": 19, "score": 0, "title": "Active control of slow light on a chip with photonic crystal waveguides", "venue": "Nature", "year": 2005 }, { "abstract": "We investigate the light emission properties of electrical dipole emitters inside 2 dimensional (2D) and 3 dimensional (3D) silicon slot waveguides and evaluate the spontaneous emission enhancement (F(p) and waveguide coupling ratio (beta) Under realistic conditions, we find that greater than 10 fold enhancement in F(p) can be achieved, together with a beta as large as 0.95. In contrast to the case of high Q optical resonators, such performance enhancements are obtained over a broad wavelength region, which can cover the entire emission spectrum of popular optical dopants such as Er. The enhanced luminescence efficiency and the strong coupling into a limited set of well defined waveguide modes enables a new class of power efficient, CMOS compatible, waveguide based light sources.", "author_names": [ "Young Chul Jun", "Ryan M Briggs", "Harry A Atwater", "Mark L Brongersma" ], "corpus_id": 1459675, "doc_id": "1459675", "n_citations": 83, "n_key_citations": 1, "score": 0, "title": "Broadband enhancement of light emission in silicon slot waveguides.", "venue": "Optics express", "year": 2009 }, { "abstract": "We demonstrate a 20 mum radius disk resonator based on Si/SiO2 slot waveguide. Quality factors around 1,000 are measured. Low effective refractive index evidences light guiding in the low index SiO2 layer.", "author_names": [ "Carlos Angulo Barrios", "Q Xu", "Jagat Shakya", "Christina Manolatou", "Michal Lipson" ], "corpus_id": 44480543, "doc_id": "44480543", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Compact silicon slot waveguide disk resonator", "venue": "2006 Conference on Lasers and Electro Optics and 2006 Quantum Electronics and Laser Science Conference", "year": 2006 } ]

[ { "abstract": "Abstract. A silicon p channel metal oxide semiconductor field effect transistor (Si PMOSFET) that is fully compatible with the standard complementary metal oxide semiconductor process is investigated based on the phenomenon of optical radiation observed in the reverse biased p n junction in the Si PMOSFET device. The device can be used either as a two terminal silicon diode light emitting device (Si diode LED) or as a three terminal silicon gate controlled diode light emitting device (Si gate controlled diode LED) It is seen that the three terminal operating mode could provide much higher power transfer efficiency than the two terminal operating mode. A new solution based on the concept of a theoretical quantum efficiency model combined with calculated results is proposed for interpreting the evidence of light intensity reduction at high operating voltages. The Si LED that can be easily integrated into CMOS fabrication process is an important step toward optical interconnects.", "author_names": [ "Kaikai Xu" ], "corpus_id": 123831798, "doc_id": "123831798", "n_citations": 11, "n_key_citations": 0, "score": 3, "title": "Structural and optical properties of silicon metal oxide semiconductor light emitting devices", "venue": "", "year": 2016 }, { "abstract": "We demonstrated a new kind of InGaN/GaN multi quantum well (MQW) light emitting diode (LED) with simplified fabrication processes, where only one round of photolithography and electrode deposition is necessary. The electrical and optical properties of this LED, which is defined as a coplanar metal semiconductor metal (CMSM) LED, were characterized. The electroluminescence spectrum only exhibits blue emission at 450 nm, meaning that the light comes exclusively from MQWs. The optical output at 20 mA was comparable to that of conventional LEDs. A shunt circuit model with a surface thin film resistance, an n+ InGaN/p GaN/n GaN structure and a p GaN/n GaN junction was proposed to explain the working mechanism of the CMSM LED. A proof of concept display was demonstrated, exploiting the promising application of CMSM LED to display.", "author_names": [ "Hao Long", "Y P Zeng", "Yang Mei", "Leiying Ying", "Baoping Zhang" ], "corpus_id": 101466179, "doc_id": "101466179", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Coplanar metal semiconductor metal light emitting devices with an n+ InGaN layer and their application to display", "venue": "", "year": 2016 }, { "abstract": "The reflectivity versus incident angle of a GaP/Au reflector, a GaP/SiO2/Au triple ODR (omni directional reflector) and a GaP/ITO/Au triple ODR was calculated. Compared to AlGaInP LEDs with a GaAs absorbing substrate, thin film LEDs with a Au reflector, a SiO2 ODR and an ITO ODR were fabricated. At a current of 20 mA, the optical output power of four samples was respectively 1.04, 1.14, 2.53 and 2.15 mW. The Au diffusion in the annealing process reduces the reflectivity of the Au/GaP reflector to 9% The different transmittance of quarter wave thickness ITO and SiO2 induces different optical output power between the SiO2 and ITO thin film LEDs. The insertion of Zn in the ITO ODR LED does not affect the light output but evidently reduces the voltage.", "author_names": [ "Wei Gao", "Weiling Guo", "DeShu Zou", "Qin Yuan", "Wenxin Jiang", "Guangdi Shen" ], "corpus_id": 107882516, "doc_id": "107882516", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "SEMICONDUCTOR DEVICES Thin film AlGaInP light emitting diodes with different reflectors", "venue": "", "year": 2010 }, { "abstract": "In order to further improve the efficiency and the spectral quality of white light LEDs new colour conversion materials which allow a selective and narrow banded conversion of the blue excitation light are needed. Quantum dots could be promising in this regard as they exhibit exactly these properties. For commercially used light sources a stable colour distribution has to be ensured over the entire lifetime. Our experiments revealed a very different degradation characteristic of phosphor and quantum dots. In this paper we present the results of different experiments which aim on the understanding of the mechanism for optical stability. We focused mainly on two degradation effects, a decrease of the photoluminescence intensity and a shift of the emission peak wavelength towards the blue.", "author_names": [ "David Schmidmayr", "Johann Zehetner", "Peter Amann" ], "corpus_id": 38700716, "doc_id": "38700716", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Investigation of optical stability issues with embedded semiconductor quantum dots used as colour conversion material in LED lighting applications", "venue": "The Tenth International Conference on Advanced Semiconductor Devices and Microsystems", "year": 2014 }, { "abstract": "In order to ensure the exchangeability of LED light engines in LED based luminaires, the Zhaga consortium develops standard specifications for the interfaces of LED light engines. The complete interface definition consists of the description of a mechanical, optical, electrical and thermal interface. The thermal interface has to ensure a good thermal contact between the engine and the fixture. Next to that, the heat spreading capabilities of both the engine and the fixture have to be taken into account in order to ensure sufficient heat spreading capabilities of complete luminaire. In order to come to a practical interface definition, a number of tests and test devices are proposed. Engines and fixture have to pass these tests in order to become Zhaga compliant. One test is the heat flux measurement on the LED light engine in order to determine the amount of heat that has to be transferred from the engine via the fixture. The second test is a test with a reference thermal engine in order to determine the heat spreading capabilities and the thermal resistance of a fixture. The final test is a test with a reference luminaire in order to determine the heat spreading capabilities of the LED light engine. With these three tests, we can realize a practical thermal interface definition.", "author_names": [ "T C Treurniet", "Karel Joop Bosschaart" ], "corpus_id": 37748229, "doc_id": "37748229", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Method for heat flux measurement on LED light engines", "venue": "2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium", "year": 2011 }, { "abstract": "The optical semiconductor unit of the present invention has an LED device, the LED device is provided with a light emitting diode (LED) and a socket, said socket mounted on the light emitting diode, LED devices having a body, LED mounted on the body, the body having a first surface, bulk electrode connected to the first surface portion.", "author_names": [ "" ], "corpus_id": 139460165, "doc_id": "139460165", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The optical semiconductor device, the optical semiconductor element and the socket", "venue": "", "year": 2010 }, { "abstract": "The determination to develop fast, efficient devices has led to vast studies on photonic circuits but it is difficult to shrink these circuits below the diffraction limit of light. However, the coupling between surface plasmon polaritons and nanostructures in the near field shows promise in developing next generation integrated circuitry. In this work, we demonstrate the potential for integrating nanoplasmonic based light guides with atomically thin materials for on chip near field plasmon detection. Specifically, we show near field electrical detection of silver nanowire plasmons with the atomically thin semiconductor molybdenum disulfide. Unlike graphene, atomically thin semiconductors such as molybdenum disulfide exhibit a bandgap that lends itself for the excitation and detection of plasmons. Our fully integrated plasmon detector exhibits plasmon responsivities of ~255 mA/W that corresponds to highly efficient plasmon detection ~0.5 electrons per plasmon)", "author_names": [ "Kenneth M Goodfellow", "Chitraleema Chakraborty", "Ryan Beams", "Lukas Novotny", "A Nick Vamivakas" ], "corpus_id": 206726737, "doc_id": "206726737", "n_citations": 31, "n_key_citations": 0, "score": 0, "title": "Direct On Chip Optical Plasmon Detection with an Atomically Thin Semiconductor.", "venue": "Nano letters", "year": 2015 }, { "abstract": "Colloidal semiconductor nanocrystals, also known as \"quantum dots\" (QDs) represent an example of a disruptive technology for display and lighting applications. The QDs' high luminescence efficiency and precisely tunable, narrow emission are nearly ideal for achieving saturated colors and enriching the display or TV color gamut. Quantum dot light emitting diodes (QLEDs) can provide saturated emission colors and allow inexpensive solution based device fabrication on almost any substrate. The first incorporation of QDs into the consumer market is using them as optical down converters. Blue light from an efficient high energy light source (e.g. GaN blue LED) is absorbed and reemitted at any desired lower energy wavelength. Alternatively, electric current can be used for direct excitation of QDs. QLEDs are an exciting technical challenge and commercial opportunity for display and solid state lighting applications. Recent developments in the field show that efficiency and brightness of QLEDs can match those of organic LEDs.", "author_names": [ "Dmitri V Talapin", "Jonathan S Steckel" ], "corpus_id": 137289394, "doc_id": "137289394", "n_citations": 116, "n_key_citations": 0, "score": 0, "title": "Quantum dot light emitting devices", "venue": "", "year": 2013 }, { "abstract": "The power output, forward voltage, conversion efficiency, and spectral characteristics of a 365 nm ultraviolet light emitting diode (LED) were measured for applications of triggering wide bandgap photoconductive switches for pulsed power applications. Pulsed currents through the LED ranged from 125 mA up to 2.2 A at widths from 10 ms up to several seconds. Using time resolved electroluminescence spectroscopy, peak emission was observed to occur at 368.5 nm for short pulses with a red shift to 371.8 nm for pulses 8 s in duration. A peak light output of 4.1 W was measured for short pulses ;50 ms) of 2.12 A, corresponding to six times the rated output specification. The LED was used to trigger a high voltage photoconductive semiconductor switch (PCSS) at voltages up to 6 kV into a high impedance load. The 365 nm LED is a promising candidate for optical triggering of PCSS devices.", "author_names": [ "Daniel Mauch", "Cameron Hettler", "William Sullivan", "Andreas A Neuber", "James C Dickens" ], "corpus_id": 26176877, "doc_id": "26176877", "n_citations": 2, "n_key_citations": 1, "score": 0, "title": "Evaluation of a Pulsed Ultraviolet Light Emitting Diode for Triggering Photoconductive Semiconductor Switches", "venue": "IEEE Transactions on Plasma Science", "year": 2015 }, { "abstract": "GaN and related materials have received a lot of attention because of their applications in a number of semiconductor devices such as LEDs, laser diodes, field effect transistors, photodetectors etc. An introduction to optical phenomena in semiconductors, light emission in p n junctions, evolution of LED technology, bandgaps of various semiconductors that are suitable for the development of LEDs are discussed first. The detailed discussion on photoluminescence of GaN nanostructures is made, since this is crucial to develop optical devices. Fabrication technology of many nanostructures of GaN such as nanowires, nanorods, nanodots, nanoparticles, nanofilms and their luminescence properties are given. Then the optical processes including ultrafast phenomena, radiative, non radiative recombination, quantum efficiency, lifetimes of excitons in InGaN quantum well are described. The LED structures based on InGaN that give various important colors of red, blue, green, and their design considerations to optimize the output were highlighted. The recent efforts in GaN technology are updated. Finally the present challenges and future directions in this field are also pointed out.", "author_names": [ "Annamraju Kasi Viswanath" ], "corpus_id": 27710958, "doc_id": "27710958", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "GaN nanostructure based light emitting diodes and semiconductor lasers.", "venue": "Journal of nanoscience and nanotechnology", "year": 2014 } ]

[ { "abstract": "Semiconductor quantum dots (QDs) exhibit unique optical and photophysical properties. These features are implemented to develop optical molecular sensor systems. The review addresses the methods to functionalize the QDs with chemical capping layers that enable the use of the resulting hybrid structures for sensing, and discusses the photophysical mechanisms being applied in the different sensor systems. Different methods to design the chemically modified QDs hybrid structures for sensing low molecular weight substrates, metal ions, anions and gases are presented. These include the functionalization of the QDs with ligands that bind ions, the modification of the QDs with substrate specific ligands or receptor units, and the chemical modification of the QDs upon sensing. Specific emphasis is directed to describe the cooperative catalytic functions of the QDs in the sensing processes, and to address the function of sensing with logic gate operations.", "author_names": [ "Ronit Freeman", "Itamar Willner" ], "corpus_id": 205815460, "doc_id": "205815460", "n_citations": 301, "n_key_citations": 0, "score": 1, "title": "Optical molecular sensing with semiconductor quantum dots (QDs)", "venue": "Chemical Society reviews", "year": 2012 }, { "abstract": "", "author_names": [ "Ronit Freeman", "Itamar Willner" ], "corpus_id": 196968382, "doc_id": "196968382", "n_citations": 68, "n_key_citations": 2, "score": 0, "title": "Optical Molecular Sensing with Semiconductor Quantum Dots (QDs)", "venue": "", "year": 2012 }, { "abstract": "Abstract Luminescent quantum dots (QDs) are colloidal semiconductor nanocrystals consisting of an inorganic core covered by a molecular layer of organic surfactants. Although QDs have been known for more than thirty years, they are still attracting the interest of researchers because of their unique size tunable optical and electrical properties arising from quantum confinement. Moreover, the controlled decoration of the QD surface with suitable molecular species enables the rational design of inorganic organic multicomponent architectures that can show a vast array of functionalities. This minireview highlights the recent progress in the use of surface modified QDs in particular, those based on cadmium chalcogenides as supramolecular platforms for light related applications such as optical sensing, triplet photosensitization, photocatalysis and phototherapy.", "author_names": [ "Marcello La Rosa", "Emily H Payne", "Alberto Credi" ], "corpus_id": 211098163, "doc_id": "211098163", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Semiconductor Quantum Dots as Components of Photoactive Supramolecular Architectures", "venue": "ChemistryOpen", "year": 2020 }, { "abstract": "Due to an internal error, the following article was added after the original publication of the special issue on Nanochemistry (11 12/2012) Semiconductor quantum dots (QDs) exhibit unique photophysical properties, turning these nanomaterials into ideal components for the development of optical or optoelectronic sensors and biosensors. Various methods and mechanisms of using QDs for sensing have been implemented, including the probing of recognition events by the luminescence of the QDs, their application in fluorescence resonance energy transfer (FRET) electron transfer (ET) chemiluminescence resonance energy transfer (CRET) and photoelectrochemical generation of photocurrents. These different mechanisms are exemplified by discussing the QD based sensing of low molecular weight substrates, chiroselective sensing of amino acids, probing of the catalytic activities of enzymes (casein kinase, tyrosinase, NAD+ dependent enzymes) and analysis of DNA and of aptamer substrate complexes. Specifically, the amplified QD based sensing of DNA using exonuclease III as target regeneration biocatalyst and the multiplexed detection of DNAs using differently sized QDs are discussed. Also, the implementation of the CRET process for the multiplexed analysis of DNA using differently sized QDs is addressed. Finally, the use of semiconductor QDs for the photoelectrochemical detection of DNA, aptamer substrate complexes and enzyme activities are discussed. Specifically, the use of QDs for photoelectrochemical sensors, using the CRET process as internal excitation light source, is described. The future applications of the various QD based sensors as analytical devices and as nanotools that probe intracellular processes are discussed.", "author_names": [ "Ronit Freeman", "Julia Girsh", "Bilha Willner", "Itamar Willner" ], "corpus_id": 97657837, "doc_id": "97657837", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Sensing and Biosensing with Semiconductor Quantum Dots", "venue": "", "year": 2012 }, { "abstract": "Featuring size tunable electrical and optical properties, semiconductor quantum dots (QDs) are appealing intensive interests in developing ingenious luminescent materials for chemosensory and biological applications. The surface modification of QDs with functional ligands not only fine tunes the physiochemical properties and fluorescence emission behaviors, but also induces the designated interplay between analytes and probes for special determination. In this review, the fundamental principles guiding the rational design of high efficiency luminescent sensors with surface engineering are overviewed. The state of the art applications of QDs based probes are highlighted for the sensing of molecular substrates and ionic species as well as various biological applications, with the inherent recognition mechanisms elaborated for representative cases. The challenge and future research direction in this emerging and promising research field are also discussed.", "author_names": [ "Jie Zhou", "Yun Liu", "Jian Tang", "Weihua Tang" ], "corpus_id": 136309705, "doc_id": "136309705", "n_citations": 56, "n_key_citations": 0, "score": 0, "title": "Surface ligands engineering of semiconductor quantum dots for chemosensory and biological applications", "venue": "", "year": 2017 }, { "abstract": "Research on fluorescent semiconductor quantum dots (QDs, or nanocrystals) has been focused towards developing analytical applications for which their robust optical properties add value. To this end, the materials must be efficiently water solubilized and functionalized. This thesis details my research in this regard, starting with the development of a one step method to produce ~10 nm hydrodynamic diameter water soluble CdSe/ZnS quantum dots through ligand exchange with a near monolayer of organosilane caps. The samples are stable for months under benchtop conditions and have high quantum yields ~60% which is unprecedented for cap exchanged QDs. Furthermore, the procedure can be applied to CdS/ZnS, ZnSe/ZnMnS/ZnS, and CuInS2/ZnS QDs. While water solubilization is necessary for the development of analytical applications, the materials must be functionalized with chemical and biological vectors for sensing applications. In this regard, small molecular reagents that can efficiently functionalize water soluble CdSe/ZnS nanocrystals have been developed. These reagents do not cause quenching or precipitation of QDs as observed with commercially available activators. Last, a ratiometric fluorescent QD reporter for O2 levels in water created by attaching multiple pyrene functional chromophores to the surface of bright, water soluble semiconductor nanocrystals. These ligands have been used with both CdSe/CdZnS and AgInS2/ZnS nanocrystals, the latter of which represents a fluorescent QD sensor with significantly reduced toxicity.", "author_names": [ "Xi Zhang" ], "corpus_id": 94630533, "doc_id": "94630533", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Semiconductor Quantum Dots Water Solubilization, Functionalization, and Ratiometric Sensing of O2", "venue": "", "year": 2014 }, { "abstract": "Semiconductor quantum dots possess unique size dependent electronic properties and are of high potential interest for the construction of functional nanodevices. Photoinduced electron and energy transfer processes between quantum dots and surface bound molecular species open up attractive routes to implement chemical switching of luminescence, which is at the basis of luminescence sensing. In this article, we discuss the general principles underlying the rational design of this kind of multicomponent species. Successively, we illustrate a few prominent examples, taken from the recent literature, of luminescent chemosensors constructed by attaching molecular species to the surface of quantum dots.", "author_names": [ "Serena Silvi", "Massimo Baroncini", "Marcello La Rosa", "Alberto Credi" ], "corpus_id": 44581401, "doc_id": "44581401", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Interfacing Luminescent Quantum Dots with Functional Molecules for Optical Sensing Applications", "venue": "Topics in Current Chemistry", "year": 2016 }, { "abstract": "Since its emergence, semiconductor nanoparticles known as quantum dots (QDs) have drawn considerable attention and have quickly extended their applicability to numerous fields within the life sciences. This is largely due to their unique optical properties such as high brightness and narrow emission band as well as other advantages over traditional organic fluorophores. New molecular sensing strategies based on QDs have been developed in pursuit of high sensitivity, high throughput, and multiplexing capabilities. For traditional biological applications, QDs have already begun to replace traditional organic fluorophores to serve as simple fluorescent reporters in immunoassays, microarrays, fluorescent imaging applications, and other assay platforms. In addition, smarter, more advanced QD probes such as quantum dot fluorescence resonance energy transfer (QD FRET) sensors, quenching sensors, and barcoding systems are paving the way for highly sensitive genetic and epigenetic detection of diseases, multiplexed identification of infectious pathogens, and tracking of intracellular drug and gene delivery. When combined with microfluidics and confocal fluorescence spectroscopy, the detection limit is further enhanced to single molecule level. Recently, investigations have revealed that QDs participate in series of new phenomena and exhibit interesting non photoluminescent properties. Some of these new findings are now being incorporated into novel assays for gene copy number variation (CNV) studies and DNA methylation analysis with improved quantification resolution. Herein, we provide a comprehensive review on the latest developments of QD based molecular diagnostic platforms in which QD plays a versatile and essential role.", "author_names": [ "Yi Zhang", "Tza-Huei Wang" ], "corpus_id": 1255105, "doc_id": "1255105", "n_citations": 119, "n_key_citations": 0, "score": 0, "title": "Quantum Dot Enabled Molecular Sensing and Diagnostics", "venue": "Theranostics", "year": 2012 }, { "abstract": "Quantum dots (QDs) are attractive semiconductor fluorescent nanomaterials with remarkable optical and electrical properties. The broad absorption spectra and high stability of QD transducers are advantageous for sensing and bioimaging. Molecular imprinting is a technique for manufacturing synthetic polymeric materials with a high recognition ability towards a target analyte. The high selectivity of the molecularly imprinted polymers (MIPs) is a result of the fabrication process based on the template tailored polymerization of functional monomers. The three dimensional cavities formed in the polymer network can serve as the recognition elements of sensors because of their specificity and stability. Appending specific molecularly imprinted layers to QDs is a promising strategy to enhance the stability, sensitivity, and selective fluorescence response of the resulting sensors. By merging the benefits of MIPs and QDs, inventive optical sensors are constructed. In this review, the recent synthetic strategies used for the fabrication of QD nanocrystals emphasizing various approaches to effective functionalization in aqueous environments are discussed followed by a detailed presentation of current advances in QD conjugated MIPs (MIP QDs) Frontiers in manufacturing of specific imprinted layers of these nanomaterials are presented and factors affecting the specific behaviour of an MIP shell are identified. Finally, current limitations of MIP QDs are defined and prospects are outlined to amplify the capability of MIP QDs in future sensing.", "author_names": [ "Monika Sobiech", "Piotr Bujak", "Piotr Lulinski", "Adam Pron" ], "corpus_id": 206144597, "doc_id": "206144597", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "Semiconductor nanocrystal polymer hybrid nanomaterials and their application in molecular imprinting.", "venue": "Nanoscale", "year": 2019 }, { "abstract": "Bright emitters with photoluminescence in the spectral region of 800 1600 nm are increasingly important as optical reporters for molecular imaging, sensing, and telecommunication and as active components in electrooptical and photovoltaic devices. Their rational design is directly linked to suitable methods for the characterization of their signal relevant properties, especially their photoluminescence quantum yield (Ph(f) Aiming at the development of bright semiconductor nanocrystals with emission >1000 nm, we designed a new NIR/IR integrating sphere setup for the wavelength region of 600 1600 nm. We assessed the performance of this setup by acquiring the corrected emission spectra and Ph(f) of the organic dyes Itrybe, IR140, and IR26 and several infrared (IR) emissive Cd(1 x)Hg(x)Te and PbS semiconductor nanocrystals and comparing them to data obtained with two independently calibrated fluorescence instruments absolutely or relative to previously evaluated reference dyes. Our results highlight special challenges of photoluminescence studies in the IR ranging from solvent absorption to the lack of spectral and intensity standards together with quantum dot specific challenges like photobrightening and photodarkening and the size dependent air stability and photostability of differently sized oleate capped PbS colloids. These effects can be representative of lead chalcogenides. Moreover, we redetermined the Ph(f) of IR26, the most frequently used IR reference dye, to 1.1 x 10( 3) in 1,2 dichloroethane DCE with a thorough sample reabsorption and solvent absorption correction. Our results indicate the need for a critical reevaluation of Ph(f) values of IR emissive nanomaterials and offer guidelines for improved Ph(f) measurements.", "author_names": [ "Soheil Hatami", "Christian Wurth", "Martin Kaiser", "Susanne Leubner", "Stefanie Gabriel", "Lydia Bahrig", "Vladimir Lesnyak", "Jutta Pauli", "Nikolai Gaponik", "Alexander Eychmuller", "Ute Resch-Genger" ], "corpus_id": 205921011, "doc_id": "205921011", "n_citations": 43, "n_key_citations": 0, "score": 0, "title": "Absolute photoluminescence quantum yields of IR26 and IR emissive Cd(1 x)Hg(x)Te and PbS quantum dots method and material inherent challenges.", "venue": "Nanoscale", "year": 2015 } ]

[ { "abstract": "In this paper, finger vein authentication, a new biometric method utilizing the vein patterns inside one's fingers for personal identification, is introduced. Vein patterns are different for each finger and for each person, and as they are hidden underneath the skin's surface, forgery is extremely difficult. These unique aspects of finger vein pattern recognition set it apart from previous forms of biometrics and have led to its adoption by the major Japanese financial institutions as their newest security technology. This paper discusses the technology and applications of finger vein authentication, as well as the importance of semiconductor devices in its future development", "author_names": [ "J Hashimoto" ], "corpus_id": 36951023, "doc_id": "36951023", "n_citations": 180, "n_key_citations": 8, "score": 1, "title": "Finger Vein Authentication Technology and Its Future", "venue": "2006 Symposium on VLSI Circuits, 2006. Digest of Technical Papers.", "year": 2006 }, { "abstract": "Finger vein authentication is one of the most accurate and reliable biometric technologies, which is widely employed in mission critical applications such as financial transactions. Section 6.1 describes the advantages of finger vein authentication as well as a brief history of the technology. Section 6.2 covers the overview of the hardware by taking an example of a commercial finger vein authentication device. Section 6.3 features the imaging technology and the matching algorithm employed by the commercial model. Section 6.4 explains two performance evaluation results based on internationally recognised biometric testing standards. Sections 6.5 and 6.6 illustrate the actual implementations of the technology in both general and financial applications. Conclusion and future plans are described in", "author_names": [ "Mitsutoshi Himaga", "Katsuhiro Kou" ], "corpus_id": 166817630, "doc_id": "166817630", "n_citations": 30, "n_key_citations": 0, "score": 0, "title": "Finger Vein Authentication Technology and Financial Applications", "venue": "", "year": 2008 }, { "abstract": "Hiroyuki Suzuki1, Jumpei Nagata1, Kazuki Hirai1, Keiichiro Kagawa2, Takashi Obi1, Nagaaki Ohyama1, Takashi Komuro3 1 Laboratory for Future Interdisciplinary Research of Science and Technology, Tokyo Institute of Technology 4259 Nagatsutacho Midoriku Yokohama, 226 8503 Japan 2 Research Institute of Electronics, Shizuoka University 3 5 1 Johoku, Hamamatsu, 432 8011 Japan 3 Graduate School of Science Engineering, Saitama University Shimo Okubo 255, Sakura ku, Saitama shi, 338 8570 Japan E mail:[email protected]", "author_names": [ "Suzuki Hiroyuki", "Nagata Jumpei", "Hirai Kazuki", "Kagawa Keiichiro", "Obi Takashi", "Ohyama Nagaaki", "Komuro Takashi" ], "corpus_id": 108358213, "doc_id": "108358213", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Improvement of Imaging system for hand waving finger vein authentication", "venue": "", "year": 2018 }, { "abstract": "Information security has become an indivisible part of the emerging Information and Communication Technology [ICT] applications. In particular, authentication plays an extremely important role in dealing with security. A review on the biometric authentication techniques and few future possibilities in the fields of Information security is presented in this work. The basis of biometrics is that an individual is identifiable by a few characteristic and physiological parameters. To affirm or determine the identity of any particular individual, most of the systems require personal recognition schemes which are distinctive and equally reliable. This assures the authentication of the people requesting their services. This ensures that only legitimate users can access the services and not anyone else. The use of biometrics also allows to establish or approve an individual's identity. The position of biometrics in the present field of security can be deduced from this work. This paper outlines a comparison between three different techniques and their advantages and disadvantages over each other. Comparing these three techniques, we were able to deduce that the finger vein recognition system showed a good balance in every aspect.", "author_names": [ "Sarah Ali Khan", "Sameena Naaz" ], "corpus_id": 216104339, "doc_id": "216104339", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Comparative Analysis of Finger Vein, Iris and Human Body Odor as Biometric Approach in Cyber Security System", "venue": "2020 2nd International Conference on Innovative Mechanisms for Industry Applications (ICIMIA)", "year": 2020 }, { "abstract": "In this Paper, Finger vein authentication is used to ensure the user identity. Finger vein technology, is one of the fastest growing method in the Biometrics. Vein patterns are different for each and ever person also they are hidden under the skins surface. Since they are situated inside forgery is extremely difficult. Near IR rays are passed through the finger and the hemoglobin pigments inside the blood blocked the rays and the patterns of vein are captured at the other side via Image sensor. HausdThorff distance technique is used to extract the Skelton pattern from the vein image. This paper discusses the utilization of Minutiae feature points in the verification tasks as geometric representation of vein pattern shape. Also discusses the technology and applications of finger vein authentication, as well as the importance of authentication in its future development.", "author_names": [ "Momodu Ibrahim", "Faris S Al-Namiy", "M Marsaline Beno", "L Rajaji" ], "corpus_id": 108515721, "doc_id": "108515721", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Biometric authentication for secured transaction using finger vein technology", "venue": "", "year": 2011 }, { "abstract": "Finger vein authentication is a new biometric method utilizing the vein patterns inside one's fingers for personal identity verification. Vein patterns are different for each finger and for each person; and as they are hidden underneath the skin's surface, forgery is extremely difficult. These unique aspects of finger vein pattern recognition set it apart from previous forms of biometrics and have led to its adoption by the major Japanese financial institutions as their newest security technology. This white paper discusses the origins, features, technology, applications and future development of finger vein authentication. Originally, the motivation to develop finger vein pattern recognition technology was born of Hitachi's advanced research to measure brain function activity in the field of medical science. In that research, near infrared light was used to observe the increase in blood flow and was found to be applicable to recognition of the finger vein pattern. As finger vein patterns differ for each finger and for each person, Hitachi thus discovered that finger vein pattern recognition is a viable biometric personal authentication technology for the commercial market. In the first phase (1997 2000) Hitachi developed its original light transmission technology for finger vein biometric authentication. As opposed to light reflection, whereby a captured image is taken from light reflected off the surface of the skin, light transmission captures a vein pattern image from light that passes through the surface of the skin (see Section 4 for details) In the second phase (2000 2003) the technology was adapted into product form, and the first physical access control system was developed and released in 2002. In 2002 research began on the logical access systems, with commercialization in Japan beginning in 2004. Hitachi developed ATM applications in 2004 and commercialized them in 2005. Finger vein authentication technology has thrived in the Japanese financial sector, with major banks in Japan employing it for ATM end user verification. The basic principle on which the finger vein authentication system is based is shown in Fig. 2. Near infrared rays generated from a bank of LEDs (light emitting diodes) penetrate the finger and are absorbed by the hemoglobin in the blood. The areas in which the rays are absorbed (i.e. veins) thus appear as dark areas in an image taken by a CCD camera located on the opposite side of the finger. Image processing can then construct a finger vein pattern from the camera image. This pattern is compressed and digitized so", "author_names": [], "corpus_id": 16178661, "doc_id": "16178661", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Finger Vein Authentication White Paper", "venue": "", "year": null }, { "abstract": "With the development of shopper physical science, the demand for straightforward, convenient, and high security authentication systems for protective personal info hold on in mobile devices has steady exaggerated. In thought of rising necessities for info protection, biometrics, that uses human physiological or activity options for private identification, has been extensively studied as an answer to security problems. However, most existing biometric systems have high complexness in time or house or each, and are so not appropriate for mobile devices. there's an extended list of accessible biometric patterns, as well as face, iris, finger print, palm print, hand shape, voice, signature and gait. joined of the most stream branches, Vein recognition bioscience could be a significantly spectacular and promising technology. This study presents a survey of finger vein recognition techniques. The merits, basic working rule, key techniques, performance analysis metrics, application field and future trends are extensively analyzed. per the theoretical analysis report in literatures and business utilization experiences, vein recognition has been proven to be associate degree effective, extremely secure and reliable selection of high exactness among all accessible biometric techniques. during this paper we have a tendency to had planned to implement the Finger Vein Recognition idea mistreatment MATLAB R2013a. The options used are Lacunareity Distance, Blanket Dimension distance, SURF (Speeded Up strong Feature) and Hareris corners, that has additional accuracy in comparison to standard strategies. Keywords bioscience, Personal identification, Finger vein recognition. ____________________________________________________________________________________________________________________", "author_names": [ "S Aparna" ], "corpus_id": 31605466, "doc_id": "31605466", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "A Novel Approach For Finger Vein Recognition Technique For Private Identification And Verification", "venue": "", "year": 2014 }, { "abstract": "Biometric technology will soon be the norm in the banking sector. According to Acuity Market Intelligence 1 physical credentials such as cash and bank cards will disappear over the next decade or so as the uptake of 'virtual credentials' iris, voice, finger vein becomes entrenched by 2030. By 2025, Acuity predicts that standard authentication for trillions of transactions will be biometric. Overall, the reason for this is that while the public recognises that data security is increasingly important, they worry that passwords and PINs are not fraud proof and biometrics answers this by delivering a faster, easier and more secure authentication process. More specifically, biometric technology adoption is accelerating because of a shift away from external feature recognition towards internal (for example, from voice to vein recognition) which offers a more streamlined and palatable customer experience.", "author_names": [ "Ravi Ahluwalia" ], "corpus_id": 115098370, "doc_id": "115098370", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Banking's biometric future", "venue": "", "year": 2016 }, { "abstract": "A review is conducted to deeply analyse and map the research landscape of current technologies in finger vein (FV) biometric authentication in medical systems into a coherent taxonomy. This research focuses on articles related to the keywords 'biometrics' 'finger veins' and 'verification' and their variations in three major databases, namely, Web of Science, ScienceDirect and IEEE Xplore. The final set of collected articles related to FV biometric authentication systems is divided into software and hardware based systems. In the first category, software development attempts are described. The experiment results, frameworks, algorithms and methods that perform satisfactorily are presented. Moreover, the experiences obtained from conducting these studies are discussed. In the second category, hardware development attempts are described. The final articles are discussed from three aspects, namely, (1) number of publications, (2) problem type, proposed solutions, best results and evaluation methods in the included studies and (3) available databases containing different scientific work collected from volunteers, such as staff and students. The basic characteristics of this emerging field are identified from the following aspects: motivations of using FV biometric technology in authentication systems, open challenges that impede the technology's utility, authors' recommendations and future research prospects. A new solution is proposed to address several issues, such as leakage of biometrics that leads to serious risks due to the use of stolen FV templates and various spoofing and brute force attacks in decentralised network architectures in medical systems, including access points and various database nodes without a central point. This work contributes to literature by providing a detailed review of feasible alternatives and research gaps, thereby enabling researchers and developers to develop FV biometric authentication medical systems further. Insights into the importance of such a technology and its integration into different medical applications and fields are also provided.", "author_names": [ "A H Mohsin", "N S Jalood", "M J Baqer", "Abdullah Hussein Alamoodi", "E M Almahdi", "A S Albahri", "M A Alsalem", "K I Mohammed", "Hussein Ali Ameen", "Salem Garfan", "A A Zaidan", "Bilal Bahaa Zaidan", "Osamah Shihab Albahri", "Shamsul Arrieya Bin Ariffin", "Ahmed Alemran", "Odai Enaizan", "Ali H Shareef", "Ali Najm Jasim" ], "corpus_id": 210887656, "doc_id": "210887656", "n_citations": 18, "n_key_citations": 0, "score": 0, "title": "Finger Vein Biometrics: Taxonomy Analysis, Open Challenges, Future Directions, and Recommended Solution for Decentralised Network Architectures", "venue": "IEEE Access", "year": 2020 }, { "abstract": "Over the years Biometric authentication system has gained widespread popularity due to the rising need for personal identification and security. The most common biometric features used in authentication systems are fingerprint, iris, hand geometry, retina, finger vein, palm vein, and voice pattern. Among them, finger vein biometric recognition system might soon surge ahead for its many advantages, such as high identification accuracy, non invasive technology, and little to no possibility of being duplicated or forged. After being motivated by the apparent benefits of finger vein authentication, many researchers have tried to develop a working model with improved performance. Since, deep learning has the ability to solve complex problems that require discovering hidden patterns in structured data and understanding intricate relationships between a large number of interdependent variables, many deep learning models were created for feature extraction and classification purposes. In this paper, existing research works of finger vein authentication based on deep learning models have been assembled and summarized. In addition, the accuracy and performance of the approaches have been highlighted to give a future direction for further research.", "author_names": [ "Fariha Elahee", "Farhana Mim", "Faizah Binte Naquib", "Sharika Tabassom", "Tonmoy Hossain", "Kazi A Kalpoma" ], "corpus_id": 231823677, "doc_id": "231823677", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Comparative Study of Deep Learning based Finger Vein Biometric Authentication Systems", "venue": "2020 2nd International Conference on Advanced Information and Communication Technology (ICAICT)", "year": 2020 } ]

[ { "abstract": "In 1929, only three years after the advent of quantum mechanics, von Neumann and Wigner showed that Schrodinger's equation can have bound states above the continuum threshold. These peculiar states, called bound states in the continuum (BICs) manifest themselves as resonances that do not decay. For several decades afterwards the idea lay dormant, regarded primarily as a mathematical curiosity. In 1977, Herrick and Stillinger revived interest in BICs when they suggested that BICs could be observed in semiconductor superlattices. BICs arise naturally from Feshbach's quantum mechanical theory of resonances, as explained by Friedrich and Wintgen, and are thus more physical than initially realized. Recently, it was realized that BICs are intrinsically a wave phenomenon and are thus not restricted to the realm of quantum mechanics. They have since been shown to occur in many different fields of wave physics including acoustics, microwaves and nanophotonics. However, experimental observations of BICs have been limited to passive systems and the realization of BIC lasers has remained elusive. Here we report, at room temperature, lasing action from an optically pumped BIC cavity. Our results show that the lasing wavelength of the fabricated BIC cavities, each made of an array of cylindrical nanoresonators suspended in air, scales with the radii of the nanoresonators according to the theoretical prediction for the BIC mode. Moreover, lasing action from the designed BIC cavity persists even after scaling down the array to as few as 8 by 8 nanoresonators. BIC lasers open up new avenues in the study of light matter interaction because they are intrinsically connected to topological charges and represent natural vector beam sources (that is, there are several possible beam shapes) which are highly sought after in the fields of optical trapping, biological sensing and quantum information.", "author_names": [ "Ashok Kodigala", "Thomas Lepetit", "Qing Gu", "Babak Bahari", "Yeshaiahu Fainman", "Boubacar Kante" ], "corpus_id": 4465627, "doc_id": "4465627", "n_citations": 345, "n_key_citations": 0, "score": 1, "title": "Lasing action from photonic bound states in continuum", "venue": "Nature", "year": 2017 }, { "abstract": "Bound states in the continuum (BICs) are widely studied for their ability to confine light, produce sharp resonances for sensing applications and serve as avenues for lasing action with topological characteristics. Primarily, the formation of BICs in periodic photonic band gap structures are driven by symmetry incompatibility; structural manipulation or variation of incidence angle from incoming light. In this work, we report two modalities for driving the formation of BICs in terahertz metasurfaces. At normal incidence, we experimentally confirm polarization driven symmetry protected BICs by the variation of the linear polarization state of light. In addition, we demonstrate through strong coupling of two radiative modes the formation of capacitively driven Freidrich Wintgen BICs, exotic modes which occur in off G points not accessible by symmetry protected BICs. The capacitance mediated strong coupling at 0deg polarization is verified to have a normalized coupling strength ratio of 4.17% obtained by the Jaynes Cummings model. Furthermore, when the polarization angle is varied from 0deg to 90deg (0deg ph 90deg) the Freidrich Wintgen BIC is modulated until it is completely switched off at 90deg. Bound states in the continuum, offering long lived, spatially confined photon states, are typically realized via geometric manipulation of symmetry. Here, the formation of bound states in the continuum is instead driven in a THz metasurface by varying the polarization.", "author_names": [ "Chan Kyaw", "Riad Yahiaoui", "Joshua A Burrow", "Viet Nhan Hao Tran", "Kyron Keelen", "Wesley Sims", "Eddie C Red", "Willie S Rockward", "Mikkel A Thomas", "Andrew M Sarangan", "Imad H Agha", "Thomas A Searles" ], "corpus_id": 227061198, "doc_id": "227061198", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Polarization selective modulation of supercavity resonances originating from bound states in the continuum", "venue": "", "year": 2020 }, { "abstract": "On chip light sources are critical for the realization of fully integrated photonic circuitry. So far, semiconductor miniaturized lasers have been mainly limited to sizes on the order of a few microns. Further reduction of sizes is challenging fundamentally due to the associated radiative losses. While using plasmonic metals helps to reduce radiative losses and sizes, they also introduce Ohmic losses hindering real improvements. In this work, we show that, making use of quasi bound states in the continuum, or supercavity modes, we circumvent these fundamental issues and realize one of the smallest purely semiconductor nanolasers thus far. Here, the nanolaser structure is based on a single semiconductor nanocylinder that intentionally takes advantage of the destructive interference between two supported optical modes, namely Fabry Perot and Mie modes, to obtain a significant enhancement in the quality factor of the cavity. We experimentally demonstrate the concept and obtain optically pumped lasing action using GaAs at cryogenic temperatures. The optimal nanocylinder size is as small as 500 nm in diameter and only 330 nm in height with a lasing wavelength around 825 nm, corresponding to a size to wavelength ratio as low as 0.6.", "author_names": [ "V M Mylnikov", "Son Tung Ha", "Zhenying Pan", "Vytautas Valuckas", "Ramon Paniagua-Dominguez", "Hilmi Volkan Demir", "Arseniy I Kuznetsov" ], "corpus_id": 212633812, "doc_id": "212633812", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Lasing Action in Single Subwavelength Particles Supporting Supercavity Modes.", "venue": "ACS nano", "year": 2020 }, { "abstract": "We have demonstrated for the first time lasing action in a Bound stae in the Continuum (BIC) based cavity. We have achieved this result on a platform made of an ensemble of dielectric resonators that is compatible with electrical pumping. Lasing action was observed at room temperature in a compact array with a footprint as small as 9x9 mm2. The lasing wavelength follows the prediction of the BIC mode as the radius is varied for different array sizes thereby demonstrating the robustness and scalability of the system. Additionally, this work paves the way for future investigation into the intriguing topological properties of BICs. Furthermore, this design can be implemented for an electrically pumped equivalent thereby taking full advantage of its power efficient performance. The fundamental principle of bound states can also be used to design in plane emitting laser.", "author_names": [ "Boubacar Kante" ], "corpus_id": 125522235, "doc_id": "125522235", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Topological photonic light sources (Conference Presentation)", "venue": "NanoScience Engineering", "year": 2016 }, { "abstract": "We demonstrate lasing action in the visible from an all dielectric metasurface. A low laser threshold is achieved with a high Q resonance due to operation at the near bound states in the continuum (BIC) regime.", "author_names": [ "Shaimaa I H Azzam", "Krishnakali Chaudhuri", "Alexei S Lagutchev", "Young S Kim", "Vladimir M Shalaev", "Alexandra Boltasseva", "Alexander V Kildishev" ], "corpus_id": 221717262, "doc_id": "221717262", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Room Temperature Lasing Action from All Dielectric Metasurfaces near Bound States in the Continuum", "venue": "2020 Conference on Lasers and Electro Optics (CLEO)", "year": 2020 }, { "abstract": "Recently, optical bound states in continuum in various passive photonic crystals have been identified and similar structures incorporated with optical gain have been reported to exhibit lasing. However, no explicit control over the type of lasing BIC has been reported. In this work, we utilize all four fundamental BICs related to the lowest energy G point of a square photonic crystal lattice. We identify the associated topological charges from experimentally obtained dispersions, finite element method simulations, as well as from spherical decomposition method based on the microscopic polarization currents in the photonic crystal plane. By tailoring the periodicity and the hole diameter of the photonic crystal slab, we selectively bring each of the four BIC resonances to a wavelength regime, where fluorescent IR702 molecules overlaid with the photonic crystal provide sufficient gain for the onset of lasing. We experimentally analyze all four observed lasing BICs by imaging their far field polarization vortices and their associated topological charges. The results correspond excellently with the transmission results as well as the simulation results in the absence of gain. Finally, we experimentally present a case where the lasing signal reveals the coexistence of two BICs with opposite topological charges, resulting in a unique polarization pattern. We believe our results enable tailoring the properties, such as polarization winding and topological charge of BICs, by a priori design and thus pave the way for a more general utilization of their appealing", "author_names": [ "Sughra Mohamed", "Jie Wang", "Heikki Rekola", "Janne Heikkinen", "Benjamin O Asamoah", "Lei Shi", "Tommi K Hakala" ], "corpus_id": 229924008, "doc_id": "229924008", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Topological charge engineering in lasing bound states in continuum", "venue": "", "year": 2020 }, { "abstract": "Photonic bound states in the continuum (BICs) are protected eigenstates in optical systems with infinite lifetimes. This unique property, which translates in infinite Q factor resonances, makes BICs extremely interesting not only from a fundamental perspective but also for various applications such as lasing and sensing. General means to achieve robust BICs are, however, elusive. Here we demonstrate analytically that BICs emerge in metasurfaces formed by arrays of detuned resonant dipolar dimers as a universal behavior occurring regardless of both dipole position within the unit cell and lattice constant in the nondiffracting regime. These resonances evolve continuously from a Fano resonance into a symmetry protected BIC as the dipole detuning vanishes. We have experimentally verified this very robust response at terahertz frequencies through dimer rod arrays with different rod sizes by simultaneously measuring the reduction of linewidth and the increase of lifetime before the BIC is formed, as it is impossible to couple to it from the continuum. Similar configurations can be straightforwardly envisioned throughout the electromagnetic spectrum, enabling a simple geometry that is easy to fabricate with resonances of arbitrarily high Q factors.", "author_names": [ "Diego Romero Abujetas", "Niels van Hoof", "Stan Ter Huurne", "Jaime Gomez Rivas", "Jose A Sanchez-Gil" ], "corpus_id": 209495100, "doc_id": "209495100", "n_citations": 43, "n_key_citations": 1, "score": 0, "title": "Spectral and temporal evidence of robust photonic bound states in the continuum on terahertz metasurfaces", "venue": "Optica", "year": 2019 }, { "abstract": "Photonic bound states in the continuum (BICs) are protected eigenstates in optical systems with infinite lifetimes. This unique property, which translates in infinite Q factor resonances, makes BICs extremely interesting not only from a fundamental perspective but also for various applications such as lasing and sensing. General means to achieve robust BICs are, however, elusive. Here we demonstrate analytically that BICs emerge in metasurfaces formed by arrays of detuned resonant dipolar dimers as a universal behavior occurring regardless of both dipole position within the unit cell and lattice constant in the nondiffracting regime. These resonances evolve continuously from a Fano resonance into a symmetry protected BIC as the dipole detuning vanishes. We have experimentally verified this very robust response at terahertz frequencies through dimer rod arrays with different rod sizes by simultaneously measuring the reduction of linewidth and the increase of lifetime before the BIC is formed, as it is impossible to couple to it from the continuum. Similar configurations can be straightforwardly envisioned throughout the electromagnetic spectrum, enabling a simple geometry that is easy to fabricate with resonances of arbitrarily high Q factors.", "author_names": [ "Diego Romero Abujetas", "Niels van Hoof", "Stan ter Huurne", "Jaime Gomez Rivas", "Jose A Sanchez-Gil" ], "corpus_id": 201248714, "doc_id": "201248714", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Spectral and temporal evidence of robust photonic bound states in the continuum on THz metasurfaces", "venue": "", "year": 2019 }, { "abstract": "In conventional materials, Cherenkov radiation (CR) due to a moving charged particle is associated with a broad frequency range and velocity threshold. Here, we show that using a periodic grating structure, which possesses photonic bound states in the continuum (BICs) and quasi BICs, unusual CR can be generated in a very narrow frequency band at a particle velocity below the common threshold. This effect arises from an interesting light amplification process in the BIC structure, which can dramatically improve the efficiencies of evanescent to propagating wave conversion and CR generation. Our results present a mechanism for realizing Cherenkov lasing at low electron velocity and may find applications in compact free electron lasers.", "author_names": [ "Yanan Song", "Ningxiao Jiang", "Liu Liu", "Xinhua Hu", "Jian Zi" ], "corpus_id": 125973144, "doc_id": "125973144", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Cherenkov Radiation from Photonic Bound States in the Continuum: Towards Compact Free Electron Lasers", "venue": "", "year": 2018 }, { "abstract": "The concept of optical bound states in the continuum (BICs) underpins the existence of strongly localized waves embedded into the radiation spectrum that can enhance the electromagnetic fields in subwavelength photonic structures. Early studies of optical BICs in waveguides and photonic crystals uncovered their topological properties, and the concept of quasi BIC metasurfaces facilitated applications of strong light matter interactions to biosensing, lasing, and low order nonlinear processes. Here we employ BIC empowered dielectric metasurfaces to generate efficiently high optical harmonics up to the 11th order. We optimize a BIC mode for the first few harmonics and observe a transition between perturbative and nonperturbative nonlinear regimes. We also suggest a general strategy for designing subwavelength structures with strong resonances and nonperturbative nonlinearities. Our work bridges the fields of perturbative and nonperturbative nonlinear optics on the subwavelength scale.", "author_names": [ "George P Zograf", "Kirill L Koshelev", "Anastasia S Zalogina", "Viacheslav Korolev", "Duk-Yong Choi", "Michael Zurch", "Christian Spielmann", "Barry Luther-Davies", "Daniil V Kartashov", "Sergey V Makarov", "Sergey S Kruk", "Yuri S Kivshar" ], "corpus_id": 221319450, "doc_id": "221319450", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "High harmonic generation from metasurfaces empowered by bound states in the continuum.", "venue": "", "year": 2020 } ]

[ { "abstract": "Injection locking properties of a semiconductor laser have been analyzed, taking into account the injected carrier density dependent refractive index in the active region. It has been found that this dependence significantly affects the injection locking properties, giving rise to a peculiar asymmetric tuning curve and dynamic instability. The instability originates from the intermode interaction via the modulation in the injected carrier density caused by intensity beat. The detuning dependence of the direct modulation response characteristics inside and outside of the locking range have also been examined.", "author_names": [ "R S Lang" ], "corpus_id": 123612253, "doc_id": "123612253", "n_citations": 611, "n_key_citations": 31, "score": 2, "title": "Injection locking properties of a semiconductor laser", "venue": "", "year": 1982 }, { "abstract": "In this paper the injection locking properties of two laterally coupled semiconductor lasers (LCSLs) are studied numerically. We consider external injection into either one (single external injection scheme) or both (simultaneous external injection scheme) of the LCSLs. We present stability maps for both schemes in the plane of the frequency detuning and the injection strength, where attention is centered on the influence of the waveguiding structures, the laser separation, the pump rate, and the frequency offset between the two coupled lasers. Our results contribute to a better understanding of LCSLs under external injection.", "author_names": [ "Nianqiang Li", "Hadi Susanto", "Benjamin R Cemlyn", "Ian D Henning", "Michael J Adams" ], "corpus_id": 115589237, "doc_id": "115589237", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Injection locking of two laterally coupled semiconductor laser arrays", "venue": "Photonics Europe", "year": 2018 }, { "abstract": "We present a theoretical and experimental investigation of injection locking of semiconductor lasers. The theoretical analysis takes into account the dependence of refractive index on the carrier density expressed by the linewidth enhancement factor a. Locking conditions and dynamic stability are analyzed. The nonzero value of a results in an increased locking bandwidth, where only part of the range corresponds to a dynamically stable state. Asymmetric characteristics are obtained for the locked power and phase as a function of frequency detuning between the master and slave laser. Outside the stable range, light injection gives rise to beat phenomena and intensity pulsations. The theoretical results were confirmed by experiments on 830 nm CSP lasers and 1.3 mm BH lasers. The experiments include the first measurements of locking bandwidth characteristics reported for 1.3 mm lasers. Power spectra are recorded under locked and near locked conditions and compared with theory. The 1.3 mm lasers are found to have a better dynamic stability than 830 nm lasers. Even so, the stability problems may exclude the particular application of injection locking where phase modulation is generated for coherent transmission.", "author_names": [ "Finn Mayer Mogensen", "Henning Lind Olesen", "Gunnar Jacobsen" ], "corpus_id": 120236600, "doc_id": "120236600", "n_citations": 405, "n_key_citations": 18, "score": 0, "title": "Locking conditions and stability properties for a semiconductor laser with external light injection", "venue": "", "year": 1985 }, { "abstract": "The injection locking properties of a newly developed waveguide based external cavity semiconductor laser have been investigated. Using the injection locking properties to measure the Q factor of complex optical cavities with unknown internal losses, has been demonstrated for the first time.", "author_names": [ "Y Fan", "Ruud M Oldenbeuving", "M R H Khan", "Chris G H Roeloffzen", "Edwin Jan Klein", "Chris J Lee", "Herman Leonard Offerhaus", "Klaus J Boller" ], "corpus_id": 13724640, "doc_id": "13724640", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Q factor measurements through injection locking of a semiconductor glass hybrid laser with unknown intracavity losses.", "venue": "Optics letters", "year": 2014 }, { "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": "The injection locking properties of self pulsation in semiconductor lasers are studied, using a phenomenological approach, based on an analogy with laser models. It has been found that the locking range is directly proportional to the input power, rather than to the square root of the input power as in injection locked microwaves or laser oscillators; the locking range is symmetric with respect to the self pulsation frequency in the free running case; in the locking state, the spectral linewidth of the self pulsation peak is equal to that of the incoming signal. These theoretical results agree very well with experimental ones, obtained on a distributed feedback three section laser.", "author_names": [ "Guang-Hua Duan", "Guillaume Pham" ], "corpus_id": 111129881, "doc_id": "111129881", "n_citations": 30, "n_key_citations": 2, "score": 0, "title": "Injection locking properties of self pulsation in semiconductor lasers", "venue": "", "year": 1997 }, { "abstract": "We experimentally and theoretically demonstrate the variety of the nonlinear dynamics exhibited by a single frequency semiconductor laser subjected to optical injection from a frequency comb. The injection parameters (the detuning and the injection strength) and the comb properties (comb spacing and the amplitude of the injected comb lines) are varied to unveil several dynamics such as injection locking, wave mixing, chaotic dynamics, and unlocked time periodic dynamics corresponding to new comb solutions. The asymmetry of the injected comb is shown to modify the size of the injection locking region in the parameter space, as well as the common properties between the new comb solutions observed and the injected comb.", "author_names": [ "Yaya Doumbia", "Tushar Malica", "Delphine Wolfersberger", "Krassimir Panajotov", "Marc Sciamanna" ], "corpus_id": 224861835, "doc_id": "224861835", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Nonlinear dynamics of a laser diode with an injection of an optical frequency comb.", "venue": "Optics express", "year": 2020 }, { "abstract": "", "author_names": [ "Rongqing Hui", "Antonio Mecozzi", "Alessandro D'Ottavi", "Paolo Spano" ], "corpus_id": 106522720, "doc_id": "106522720", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Injection locking properties of DFB semiconductor lasers", "venue": "12th IEEE International Conference on Semiconductor Laser", "year": 1990 }, { "abstract": "Abstract Properties of attractors and basins of the locking unlocking bistability in an optically injected semiconductor laser are investigated to study the bistable operating conditions. The attractors of the injection locked and unlocked states are a fixed point and a period one limit cycle, respectively. The presence of the intrinsic noise makes the system operated at operating conditions close to the bistability boundaries unconditionally injection locked or unlocked, resulting in the disappearance of attractors. The basins and basin boundary exhibit fractal like structure which causes difficulty in controlling the bistable operation near the basin boundary. The presence of the intrinsic noise induces a jump of the orbit of an initial condition close to the basin boundary from the basin of one attractor to that of the other, resulting in the increased degree of the difficulty. The possibility of such a jump is higher for an operating condition showing a more complex basin boundary. Hence, how noise of a given strength affects the operation of a system under different operating conditions is related to the dimension of the basin boundary of the system. The dimension of the basin boundary as a function of the operating condition is thus computed to quantitatively characterize the fractal structure. Both fractal fractal and fractal smooth metamorphoses are found to happen in the system.", "author_names": [ "Sheng-Kwang Hwang", "Jian Liu" ], "corpus_id": 122195424, "doc_id": "122195424", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Attractors and basins of the locking unlocking bistability in a semiconductor laser subject to strong optical injection", "venue": "", "year": 1999 }, { "abstract": "Abstract The injection locking characteristics of a multi mode semiconductor laser are considered. A formalism is developed to investigate the stability properties of an arbitrary laser mode subject to optical injection. The formalism is used to show that the relaxation oscillation frequency (ROF) in a semiconductor laser subject to optical injection is increased relative to that of the free running laser diode. Methods of utilizing positive detuning to determine the best approach of increasing the ROF of a semiconductor laser via injection locking are considered.", "author_names": [ "R J Jones", "Paul S Spencer", "K Alan Shore" ], "corpus_id": 121040489, "doc_id": "121040489", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Influence of detuned injection locking on the relaxation oscillation frequency of a multimode semiconductor laser", "venue": "", "year": 2000 } ]

[ { "abstract": "Preface 1. Introduction 2. Classical propagation 3. Interband absorption 4. Excitons 5. Luminescence 6. Semiconductor quantum wells 7. Free electrons 8. Molecular materials 9. Luminescence centres 10. Phonons 11. Nonlinear optics Appendix A: Electromagnetism in dielectrics Appendix B: Quantum theory of radiative absorption and emission Appendix C: Band theory Appendix D: Semiconductor p i n diodes", "author_names": [ "Mark Fox" ], "corpus_id": 6015910, "doc_id": "6015910", "n_citations": 2338, "n_key_citations": 133, "score": 1, "title": "Optical Properties of Solids", "venue": "", "year": 2002 }, { "abstract": "", "author_names": [ "A M Fox" ], "corpus_id": 122290865, "doc_id": "122290865", "n_citations": 1, "n_key_citations": 1, "score": 0, "title": "Optical Properties of Excited States in Solids", "venue": "", "year": 1994 }, { "abstract": "Although the field of nonlinear optics is over 25 years old. our understanding of the nonlinear optical properties of solids is poor. For kh(3) simple bonding molecular orbital approaches1 are unable to account in a quantitative way for the magnitude, dispersion or anisotropy. On the other hand, the number of full band structure calculations of the nonlinear optical constants of solids, arid semiconductors in particular, is small. The difficulties associated with these calculations is two fold: first is the complex nature of the nonlinear response function itself, and second is the requirement of knowing both the electron energy bands and wavefunctions through the Brillouin zone. The only previous full band structure calculation of kh(3) focussed solely on the zero frequency limit and did not address its anisotropy which has been known for some time3,4. It has been suggested by some authors1 that the magnitude and anisotropy of kh(3) could only be understood in terms of local field effects.", "author_names": [ "David J Moss", "Eric C Fox", "J E Sipe", "Henry M van Driel" ], "corpus_id": 138162377, "doc_id": "138162377", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "THIRD HARMONIC GENERATION IN CRYSTALLINE AND AMORPHOUS SILICON", "venue": "", "year": 1988 }, { "abstract": "model. A final chapter gives a brief introduction to the problem of ergodicity in the foundation of statistical mechanics. The book contains a beautiful selection of topics presented with the pioneering insights of the authors, and gives concise and clear review of a wide range of ideas. The field is difficult and technical, and so the book will require some effort and patience on the part of the reader. There are also a number of unfortunate typing errors, including errors in some equations. This means that the book may not be suitable as an exclusive first introduction to the topics, and would probably benefit from being read in conjunction with other texts. However, it is rarely the case that a review by pioneers would be anything other than full of insight. This book is no exception. A scientifically mature reader would hence benefit from using it both as an overview of the field, and as a lifelong reference guide to some of its major techniques.", "author_names": [ "Bill Barnes" ], "corpus_id": 122893244, "doc_id": "122893244", "n_citations": 41, "n_key_citations": 2, "score": 0, "title": "Optical Properties of Solids, 2nd edn, by Mark Fox", "venue": "", "year": 2011 }, { "abstract": "inclusion of problems, and solutions? perhaps even the smell of the paper/ink? I doubt there is one criterion (though my local book shop groups books by the colour of the cover an interesting approach! My list of favourites just gained a new recruit, Optical Properties of Solids, by Mark Fox. Each of us has I suspect a list of favourite text books. Our choices are in part based on the particular topics covered in a book, but I fancy that much to do with the choice comes down to the approach adopted by the author, especially the extent to which that resonates with our own way of thinking. My initial reading of this book was that it did not follow an approach that I had an immediate empathy for. There are two approaches that often seem to define the discipline of physics: trying to understand why things are the way they are, and identifying how we know the things we know. Whilst these are skills, perhaps even ideologies, that we hope our students may come to adopt, they are not always the best ways of initiating students in new topic areas. It seems to me that Mark Fox understands this point very well. The topic of optical materials could fill volumes, yet he has chosen his material carefully, and has in particular chosen the level of discussion with care too, frequently making simple statements about how things are, e.g. sometimes giving formulae without derivation. Initially I found this rather sweeping approach dissatisfying, but more thought, and especially trying out some of the material on my own students, quickly showed me its value, it is above all accessible. The key to this book is that the connections with the underlying physics are always at the forefront and clearly identified. One example of this is the care taken over the section concerning the physics of oscillators in Chapter 2. This topic underpins so much of how we understand many optical (and other) materials that without such a clear grounding students will not easily gain the physical understanding that they may wish, and certainly need. Fox has appreciated this point, and has also provided exercises to reinforce students' learning in this vital area. In addition to such key fundamentals, the book also contains a number of insights that make a real difference, and are all too often left from many texts. As an example, in his discussion on oscillators, Fox shows how one can understand the fact that a resonance can influence the refractive index of a material over a wider spectral range that the associated absorption. This second edition of the book is also up to date in that it includes many of the new areas that students and others are likely to want to explore, for example plasmonics, carbon nanostructures, sources for single photons (such as NV centres in diamond) and negative refraction. Whilst no introductory text can go into great depth on such topics, the fact that Fox has introduced them, and related their properties to topics covered elsewhere in the book, does make the introduction to these new topics of considerable value. Whilst they will not be enough for someone embarking on research in these areas, they will provide the basis for future study, especially when combined with the well prepared suggestions for further reading. All in all I think this is set to become a standard work. Fox has woven together an informative and practical text, rooted in the underlying physics that will help students build an understanding of the optical properties of everything from glass to graphene.", "author_names": [ "Derry Wynn Jones" ], "corpus_id": 122482324, "doc_id": "122482324", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Soap, Science and Flat Screen TVs: A History of Liquid Crystals, by David Dunmur and Tim Sluckin", "venue": "", "year": 2011 }, { "abstract": "We compare the physical and morphological properties of z 2 Lyman alpha emitting galaxies (LAEs) identified in the HETDEX Pilot Survey and narrow band studies with those of z 2 optical emission line galaxies (oELGs) identified via HST WFC3 infrared grism spectroscopy. Both sets of galaxies extend over the same range in stellar mass (7.5 logM 10.5) size (0.5 R 3.0 kpc) and star formation rate ~1 SFR 100) Remarkably, a comparison of the most commonly used physical and morphological parameters stellar mass, half light radius, UV slope, star formation rate, ellipticity, nearest neighbor distance, star formation surface density, specific star formation rate, [O III] luminosity, and [O III] equivalent width reveals no statistically significant differences between the populations. This suggests that the processes and conditions which regulate the escape of Ly alpha from a z 2 star forming galaxy do not depend on these quantities. In particular, the lack of dependence on the UV slope suggests that Ly alpha emission is not being significantly modulated by diffuse dust in the interstellar medium. We develop a simple model of Ly alpha emission that connects LAEs to all high redshift star forming galaxies where the escape of Ly alpha depends on the sightline through the galaxy. Using this model, we find that mean solid angle for Ly alpha escape is 2.4+ 0.8 steradians; this value is consistent with those calculated from other studies.", "author_names": [ "Alex Hagen", "Gregory R Zeimann", "Christopher Behrens", "Robin Ciardullo", "Henry S Grasshorn Gebhardt", "Caryl Gronwall", "Joanna S Bridge", "Derek B Fox", "Donald P Schneider", "Jonathan R Trump", "Guillermo A Blanc", "Y K Chiang", "Taylor Steven Chonis", "Steven L Finkelstein", "Gary J Hill", "Shardha Jogee", "Eric Gawiser" ], "corpus_id": 118656213, "doc_id": "118656213", "n_citations": 40, "n_key_citations": 8, "score": 0, "title": "HST Emission Line Galaxies at z 2: Comparing Physical Properties of Lyman Alpha and Optical Emission Line Selected Galaxies", "venue": "", "year": 2015 }, { "abstract": "In the present work we study the growth by pulsed laser deposition of YBa$_2$Cu$_3$O$_{7 \\delta} (YBCO) films on the r cut sapphire substrates. To improve the matching of the lattice parameters between the substrate and the film we use CeO$_{2} buffer layer, recrystallized prior to the deposition of YBCO. The optimal thickness and temperature of recrystallization of the buffer layer is first determined using atomic force microscopy (AFM) and X ray diffraction. Next, we use the AFM to examine the dependence of YBCO film roughness on the film thickness, and we study the homogeneity of magnetic flux penetration into the films by magneto optical imaging. We find that the superconducting critical temperature and critical current density of these films are very similar to those of YBCO films grown on well matched substrates. It appears that the microstructure of YBCO films is affected by structural defects in the buffer layer as well as variations in oxygen deficiency, which results in high values of critical current density suitable for application.", "author_names": [ "Irina Abaloszewa", "Piotr Gierlowski", "Aleksander Abaloszew", "Irina V Zaytseva", "Marta Aleszkiewicz", "Yevgen Syryanyy", "V L Bezusyy", "A Malinowski", "Marta Z Cieplak", "Marek Jaworski", "Marcin Konczykowski", "Adam Abramowicz", "Stefan Chromik", "Ewha Womans University Department of Physics", "Polish Academy of Sciences", "", "Laboratoire des Solides Irradies Ceadsmiramiscnrs UMR7642", "Ecole Nationale Polytechnique", "Warsaw University of Technology", "Institute of Electronic Systems", "Institute of Process Engineering", "Slovak Academy of Sciences", "Slovak Republic" ], "corpus_id": 226975802, "doc_id": "226975802", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Properties of YBa$_2$Cu$_3$O$_{7 \\delta} films grown by pulsed laser deposition on CeO$_2$ buffered sapphire", "venue": "", "year": 2020 }, { "abstract": "Despite the recent surge of interest in two dimensional (2D) inorganic nanosheets derived from photoactive coordination polymers of lanthanide ions having interesting optical properties, research in this area is still in its infancy. Luminescent lanthanide ions, Eu(iii) or/and Tb(iii) as well as a bis terpyridine ligand (L) were used in this study as the building blocks for the synthesis of the archetypical layered structure of coordination polymers (CPs) (L*Eu/L*Tb) 2D nanosheets were obtained through exfoliation of the layered precursor of CPs in a suitable solvent system following a sonication assisted strategy. These nanosheets exhibit lateral sizes on the micrometer scale (0.3 1 mm) and an ultrathin thickness of 2 6.5 nm. 1,1 Diamino 2,2 dinitroethene or FOX 7 is an insensitive high explosive; in a binder mixture, it exhibits a slightly superior detonation velocity of 8870 m s 1 in comparison to RDX. The insensitive nature of FOX 7 makes it a key component for the development of low vulnerable high explosive compositions for further application in weaponry. The growing demand for FOX 7, for use as a suitable replacement of conventional explosives, is of serious concern to human security. Achieving rapid and efficient detection of this unexplored explosive is a challenging task. In the present study, the developed luminescent nanosheets were used for the first time for micromolar level detection of FOX 7 both in solution and in the solid state. A visually distinct color change of the nanosheets from red (L*Eu) and green (L*Tb) to colorless was witnessed upon UV light irradiation during the detection process. Notably, the solid state detection technique could be exploited for developing a commercial spray kit for quick onsite screening of this important explosive.", "author_names": [ "Tufan Singha Mahapatra", "Ananta Dey", "Harwinder Singh", "Sk Saddam Hossain", "Amal Kumar Mandal", "Amitava Das" ], "corpus_id": 210991015, "doc_id": "210991015", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Two dimensional lanthanide coordination polymer nanosheets for detection of FOX 7+", "venue": "Chemical science", "year": 2019 }, { "abstract": "A comprehensive analysis of guided modes of a novel type of a planar Bragg reflection waveguide which consists of a low refractive index guiding layer sandwiched between two finite aperiodic mirrors is presented. The layers in the mirrors are aperiodically arranged according to the Kolakoski substitution rule. In such a waveguide light is confined inside the core by Bragg reflection from the mirrors, while dispersion characteristics of guided modes strongly depend on aperiodicity of the cladding. Using the transfer matrix formalism bandgap conditions, dispersion characteristics and mode profiles of the guided modes of such Bragg reflection waveguide are studied. (c) 2015 Optical Society of America OCIS codes: (130.3120) Integrated optics devices; (130.5296) Photonic crystal waveguides; (230.7390) Waveguides, planar; (230.4170) Multilayers; (310.4165) Multilayer design. References and links 1. A. J. Fox, \"The grating guide A component for integrated optics,\" Proceedings of IEEE 62, 644 645 (1974) 2. P. Yeh, and A. Yariv, \"Bragg reflection waveguides,\" Opt. Commun. 19, 427 430 (1976) 3. P. Yeh, A. Yariv, and E. Marom,\"Theory of Bragg fiber,\" J. Opt. Soc. Am. 68, 1196 1201 (1978) 4. Qing Hu, Liu Yang Sun, Di Hu Xu, Yu Zhou, Ru Wen Peng, and Mu Wang, \"Tunable multimode and narrowband in a photonic quasicrystal waveguide,\" J. Nanosci. Nanotechnol. 13, 873 877 (2013) 5. I. A. Sukhoivanov, S. O. Iakushev, O. V. Shulika, A. Diez, and M. Andres, \"Femtosecond parabolic pulse shaping in normally dispersive optical fibers,\" Opt. Express 21, 17769 17785 (2013) 6. D. N. Chigrin, A. V. Lavrinenko, and C. S. Torres, \"Nanopillars photonic crystal waveguides,\" Opt. Express 12, 617 622 (2004) 7. A. W. Snyder, and J. D. Love, Optical Waveguide Theory (Chapman and Hall, London, New York, 1983) 8. P. Russell, \"Photonic crystal fibers,\" Science 299, 358 362 (2003) 9. B. Nistad, M. W. Haakestad, and J. Skaar, \"Dispersion properties of planar Bragg waveguides,\" Opt. Commun. 265, 153 160 (2006) 10. V. I. Fesenko, V. R. Tuz, P. P. Rocha Garcia, and I. A. Sukhoivanov, \"Dispersion properties of a one dimensional aperiodic OmniGuide structure,\" in Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications VIII, S. Yin and R. Guo, eds. Proc. SPIE 9200, 1 7 (2014) 11. J. Li, and K. S. Chiang, \"Light guidance in a photonic bandgap slab waveguide consisting of two different Bragg reflectors,\" Opt. Commun. 281, 5797 5803 (2008) 12. V. I. Fesenko, I. A. Sukhoivanov, S. N. Shul'ga, and J. A. Andrade Lucio, \"Propagation of electromagnetic waves in anisotropic photonic structures,\" in Advances in Photonic Crystals, Vittorio M. N. Passaro, ed. (InTech, Rijeka, 2013) pp 79 105. 13. S. Dasgupta, A. Ghatak, and B. P. Pal, \"Analysis of Bragg reflection waveguides with finite cladding: An accurate matrix method formulation,\" Opt. Commun. 279, 83 88 (2007) 14. B. R. West, and A. S. Helmy, \"Properties of the quarter wave Bragg reflection waveguide: Theory,\" J. Opt. Soc. Am. B 23, 1207 1220 (2006) 15. Yu Li, Yanping Xi, Xun Li, and Wei Ping Huang, \"A single mode laser based on asymmetric Bragg reflection waveguides,\" Opt. Express 17, 11179 11186 (2009) 16. Bishnu P. Pal, Somnath Ghosh, R. K. Varshney, Sonali Dasgupta, Ajoy Ghatak, \"Loss and dispersion tailoring in 1D photonics band gap Bragg reflection waveguides: Finite chirped claddings as a design tool,\" Opt. Quant. Electron. 39, 983 993 (2007) 17. Y. Fink, J. N. Winn, S. Fan, C. Chen, J. Michel, J. D. Joannopoulos, and E. L. Thomas, \"A dielectric omnidirectional reflector,\" Science 282, 1679 1682 (1998) 18. M. Ibanescu, Y. Fink, S. Fan, E. L. Thomas, and J. D. Joannopoulos, \"An all dielectric coaxial waveguide,\" Science 289, 415 419 (2000) 19. S. G. Johnson, M. Ibanescu, M. Skorobogatiy, O. Weisberg, T. D. Engeness, M. Soljacic, S. A. Jacobs, J. D. Joannopoulos, and Y. Fink, \"Breaking the glass ceiling: hollow OmniGuide fibers,\" in Photonic Bangap Materials and Devices, A. Adibi, A. Scherer and Shawn Yu Lin, eds. Proc. SPIE 4655, 1 15 (2002) 20. D. Lusk, I. Abdulhalim, and F. Placido, \"Omnidirectional reflection from Fibonacci quasi periodic one dimensional photonic crystal,\" Opt. Commun. 198, 273 279 (2001) 21. F. Qiu, R. W. Peng, X. Q. Huang, X. F. Hu, Mu Wang, A. Hu, S. S. Jiang, and D. Feng, \"Omnidirectional reflection of electromagnetic waves on Thue Morse dielectric multilayers,\" Europhys. Lett. 68, 658 (2004) 22. A. Barriuso, J. Monzon, L. Sanchez Soto, and A. Felipe, \"Comparing omnidirectional reflection from periodic and quasiperiodic one dimensional photonic crystals,\" Opt. Express 13, 3913 3920 (2005) 23. V. I. Fesenko, V. R. Tuz, and I. A. Sukhoivanov, \"Optical characterization of the aperiodic multilayered anisotropic structure based on Kolakoski sequence,\" in Integrated Optics: Physics and Simulations, P. Cheben, J. Ctyroky and I. Molina Fernandez, eds. Proc. SPIE 8781, 87811C 1 87811C 7 (2013) 24. V. I. Fesenko, \"Aperiodic birefringent photonic structures based on Kolakoski sequence,\" Waves Rand. Complex 24, 174 190 (2014) 25. V. I. Fesenko, \"Omnidirectional reflection from generalized Kolakoski multilayers,\" Prog. Electromagn. Res. M 41, 33 41 (2015) 26. V. R. Tuz, \"Optical properties of a quasiperiodic generalized Fibonacci structure of chiral and material layers,\" J. Opt. Soc. Am. B 26, 627 632 (2009) 27. V. R. Tuz and V. B. Kazanskiy \"Electromagnetic scattering by a quasiperiodic generalized multilayer Fibonacci structure with grates of magnetodielectric bars,\" Waves Rand. Complex 19, 501 508 (2009) 28. V. R. Tuz, \"A peculiarity of localized mode transfiguration of a Cantor like chiral multilayer,\" J. Opt. A: Pure Appl. Opt. 11, 125103 (2009) 29. W. Kolakoski, \"Self generating runs, Problem 5304,\" Amer. Math. Monthly 72, 674 (1965) 30. B. Sing, \"Kolakoski sequences an example of aperiodic order,\"J. Non Cryst. Solids 334, 100 104 (2004) 31. J. S. I, Y. Park, and H. Jeon, \"One dimensional photonic crystal waveguide: A frame for photonic integrated circuits,\" J. Korean Phys. Soc. 39, 994 997 (2001) 32. J. S. I, Y. Park, and H. Jeon, \"Optimal design for one dimensional photonic crystal waveguide,\" J. Light. Tech. 22, 509 513 (2004) 33. G. P. Agrawal, Nonlinear Fiber Optics. Third Edition (Academic Press, San Diego, 2001) 34. J. Li, and K. S. Chiang, \"Guided modes of one dimensional photonic bandgap waveguides,\" J. Opt. Soc. Am. A 24, 1942 1950 (2007) 35. F. Villa, and J. Gaspar Armenta, \"Photonic crystal to photonic crystal surface modes: narrowbandpass filters,\" Opt. Express 12, 2338 2355 (2004)", "author_names": [ "Volodymyr I Fesenko", "Vladimir R Tuz", "Oleksiy V Shulika", "Igor A Sukhoivanov" ], "corpus_id": 119250226, "doc_id": "119250226", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Dispersion properties of a nanophotonic Bragg waveguide with finite aperiodic cladding", "venue": "", "year": 2015 }, { "abstract": "The study of crystal optics is largely a matter of solid geometry, and demands clear visualization of optical properties in their three dimensional relations. To aid students in visualizing these relations, numerous models of wood, wire, glass, and plaster have been devised,l and have proven to be of definite value. The models described in this paper were designed, in part to supplement, and in part to substitute for standard types already in use. Following the precedent of Wright' and Rogers,t emphasis is placed on the indicatrix, or index ellipsoid, and its relations to crystallographic directions and to common optical phenomena. Relations heretofore shown only by tqo dimensional drawings, by solid opaque models, or by elusive wire \"bird cages\" are clearly represented in three dimensions by transparent models made of sheet celluloid. The models described below were constructed for the Petrographic Laboratory of the University of Kansas by student workers as a project under the National Youth Administration. Particular credit is due to Mr. Hugh Magruder and to Mr. Raymond Leonard for skilled workmanship and for ingenuity in working out details of construction. Photographs of the models were made by Mr' Oren Bingham, director of the University Photographic Bureau.", "author_names": [ "", "T U Surur", "Uniaersi'ty of Kamsas", "- Kamsas" ], "corpus_id": 211255835, "doc_id": "211255835", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "MODELS TO AID IN VISUALIZING THE OPTICAL PROPERTIES OF CRYSTALS Henor,n", "venue": "", "year": 2007 } ]

[ { "abstract": "Micro electro mechanical systems (MEMS) have experienced an explosive growth over the past few years driven mainly by its physical properties and its promising technological applications in many different fields, particularly in space and Radio Frequency (RF) systems. MEMS technology exhibits greater advantages over the existing semiconductor switches. In this paper, electro thermal performances of a two hot arms actuator MEMS switch have been investigated. The switch is designed using CST Microwave Studio. Some mathematical equations have been developed to see the temperature distribution of the hot arms as voltage applied on it. Based on this thermal distribution, the linear thermal expansion of the hot arms and the air gap used in this switch is expressed mathematically. The developed equations have been solved and analyzed using the MATLAB software. This analysis shows that this MEMS switch has a wider range of linear operation and has extremely higher breakdown voltage.", "author_names": [ "M Asaduzzaman", "Soren Peik", "Mohammed Shoaib" ], "corpus_id": 15188421, "doc_id": "15188421", "n_citations": 2, "n_key_citations": 0, "score": 1, "title": "Electro thermal and mechanical analysis of a MEMS switch", "venue": "International Conference on Electrical Computer Engineering (ICECE 2010)", "year": 2010 }, { "abstract": "The micromachining technology that emerged in the late 1980s can provide micron sized sensors and actuators. These micro transducers are able to be integrated with signal conditioning and processing circuitry to form micro electromechanical systems (MEMS) that can perform real time distributed control. This capability opens up a new territory for flow control research. On the other hand, surface effects dominate the fluid flowing through these miniature mechanical devices because of the large surface to volume ratio in micron scale configurations. We need to reexamine the surface forces in the momentum equation. Owing to their smallness, gas flows experience large Knudsen numbers, and therefore boundary conditions need to be modified. Besides being an enabling technology, MEMS also provide many challenges for fundamental flow science research.", "author_names": [ "Chih-Ming Ho", "Yu-Chong Tai" ], "corpus_id": 16413008, "doc_id": "16413008", "n_citations": 1186, "n_key_citations": 17, "score": 0, "title": "MICRO ELECTRO MECHANICAL SYSTEMS (MEMS) AND FLUID FLOWS", "venue": "", "year": 1998 }, { "abstract": "This paper deals with a relatively new area of radio frequency (RF) technology based on microelectro mechanical systems (MEMS) RF MEMS provides a class of new devices and components which display superior high frequency performance relative to conventional (usually semiconductor) devices, and which enable new system capabilities. In addition, MEMS devices are designed and fabricated by techniques similar to those of very large scale integration, and can be manufactured by traditional batch processing methods. In this paper, the only device addressed is the electrostatic microswitch perhaps the paradigm RF MEMS device. Through its superior performance characteristics, the microswitch is being developed in a number of existing circuits and systems, including radio front ends, capacitor banks, and time delay networks. The superior performance combined with ultra low power dissipation and large scale integration should enable new system functionality as well. Two possibilities addressed here are quasi optical beam steering and electrically reconfigurable antennas.", "author_names": [ "Elliott R Brown" ], "corpus_id": 382198, "doc_id": "382198", "n_citations": 646, "n_key_citations": 23, "score": 0, "title": "RF MEMS switches for reconfigurable integrated circuits", "venue": "", "year": 1998 }, { "abstract": "Electrostatically actuated microswitches and relays have been developed at Northeastern University and Analog Devices, Inc. Here, we report a steady state thermal electrical finite element model of microswitches with gold gold contacts. The modeling results show that in a microswitch with a typical geometry, the thermal constriction occurs in the thin film trace leading up to the contact, and not at the contact interface. The model correctly predicts the switch voltage at which the drain trace melts, but underestimates the switch resistance, and therefore overestimates the failure current. SEM images indicate that the contact area increases significantly with current.", "author_names": [ "X T Yan", "Nicol E McGruer", "G G Adams", "Sumit Majumder" ], "corpus_id": 31897362, "doc_id": "31897362", "n_citations": 16, "n_key_citations": 2, "score": 0, "title": "Finite element analysis of the thermal characteristics of MEMS switches", "venue": "TRANSDUCERS '03. 12th International Conference on Solid State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664)", "year": 2003 }, { "abstract": "This paper presents a detailed steady state thermal analysis of RF MEMS capacitive switches. In the up state position, the maximum temperature on the bridge occurs at the center and is only 50/spl deg/ and 70/spl deg/C for 1 /spl mu/m thick gold and aluminum membranes, respectively, for a power dissipation in the bridge of 20 mW. This corresponds to an incident RF power of 10 W for C/sub u/ 100 fF at 12 GHz (or C/sub u/ 35 fF at 35 GHz) and R/sub s/ 0.5 /spl Omega/ In the down state position, it is shown that the bridge temperature does not increase considerably for an incident power of 1 W, and therefore, does not contribute to the reliability problems at high RF powers. On the other hand, it is our opinion that the RF current density on the leading edge of the bridge membrane is the main factor of the failure of MEMS capacitive switches at high RF powers. Two dimensional temperature measurements are currently being done at Rockwell Scientific, and will be presented at the conference.", "author_names": [ "J B Rizk", "E Chaiban", "Gabriel M Rebeiz" ], "corpus_id": 23262625, "doc_id": "23262625", "n_citations": 76, "n_key_citations": 1, "score": 0, "title": "Steady state thermal analysis and high power reliability considerations of RF MEMS capacitive switches", "venue": "2002 IEEE MTT S International Microwave Symposium Digest (Cat. No.02CH37278)", "year": 2002 }, { "abstract": "From the Publisher: Practical and theoretical coverage of RF MEMS for circuits and devices New RF and microwave frequency MEMS (microeletromechanical systems) have potentially enormous and widespread applications in the telecommunications industry. Components based on this technologysuch as switches, varactors, and phase shiftersexhibit virtually no power consumption or loss, making them ideally suited for use in modern telecommunications and wireless devices. This book sets out the basics of RF MEMS and describes how to design practical devices and circuits. As well as covering fundamentals, Gabriel Rebeiz offers expert tips for designers and presents a range of real world applications. Throughout, the author utilizes actual engineering examples to illustrate basic principles in theory and practice. Detailed discussion of cutting edge fabrication and packaging techniques is provided. Suitable as a tutorial for electrical and computer engineering students, or as an up to date reference for practicing circuit designers, RF MEMS provides the most comprehensive available survey of this new and important technology. Author Biography: Gabriel M. Rebeiz received his PhD from the California Institute of Technology, and is Professor of Electrical and Computer Engineering at the University of Michigan, Ann Arbor. In 1991 he was the recipient of the National Science Foundation Presidential Young Investigator Award, and in 2000 was the corecipient of the IEEE Microwave Prize. A Fellow of the IEEE and a consultant to Rockwell, Samsung, Intel, Standard MEMS, and Agilent, he has published extensively in the field of microwave technology and in the area of RF MEMS.", "author_names": [ "Gabriel M Rebeiz" ], "corpus_id": 108034421, "doc_id": "108034421", "n_citations": 1856, "n_key_citations": 154, "score": 0, "title": "RF MEMS: Theory, Design and Technology", "venue": "", "year": 2003 }, { "abstract": "This paper reports two unique mechanisms using \"V shape\" electro thermal actuators to realize large displacement and reliable contact in MEMS switches. The first mechanism is a novel displacement amplification system that enables a large in plane traveling distance for closing the gap between switch contacts. The structure features a movable end and pivot joints connecting to the amplification beam that can result in smaller actuating force distinguishing this mechanism from others. The second mechanism involves a unique latching system to provide a large lateral force for reliable contact. In both mechanisms, out of plane displacements are minimized due to the structural symmetry of the \"V shape\" actuators. The devices are fabricated using PolyMUMPS process. At 1 V driving voltage for 2 pairs of 3 arm V shape actuators, the displacement amplification system provides a gain of ~6.5 while consuming 2x3.8 mW power. Each 4 arm V shape latching actuator generates ~2.7 um displacement and ~240 uN contact force with a power consumption of ~2.2 mW.", "author_names": [ "Jay J Khazaai", "M Haris", "Hongwei Qu", "James Melvin Slicker" ], "corpus_id": 38572053, "doc_id": "38572053", "n_citations": 14, "n_key_citations": 1, "score": 0, "title": "Displacment amplification and latching mechanism using V shape actuators in design of electro thermal MEMS switches", "venue": "2010 IEEE Sensors", "year": 2010 }, { "abstract": "MEMS are rapidly emerging as critical components in the telecommunications industry. This enabling technology is currently being implemented in a variety of product and engineering applications. MEMS are currently being used as optical switches to reroute light, tunable filters, and mechanical resonators. Radio frequency (RF) MEMS must be compatible with current Gallium Arsenide (GaAs) microwave integrated circuit (MMIC) processing technologies for maximum integration levels. The RF MEMS switch discussed in this paper was fabricated using various layers of polyimide, silicon oxynitride (SiON) gold, and aluminum monolithically fabricated on a GaAs substrate. Fig. 1 shows a metal contacting series switch. This switch consists of gold signal lines (transmission lines) and contact metallization. SiON was deposited to form the fixed fixed beam, and aluminum was deposited to form the top actuation electrode. To ensure product performance and reliability, RF MEMS switches are tested at both the wafer and package levels. Various processing irregularities may pass the visual inspection but fail electrical testing. This paper will focus on the failure mechanisms found in the first generation of RF MEMS developed at Sandia National Laboratories. Various tools and techniques such as scanning electron microscopy (SEM) resistive contrast imaging (RCI) focused ion beam (FIB) and thermally induced voltage alteration (TIVA) have been employed to diagnose the failure mechanisms. The analysis performed using these tools and techniques led to corrective actions implemented in the next generation of RF MEMS metal contacting series switches.", "author_names": [ "Jeremy A Walraven", "Edward I Cole", "Lynn R Sloan", "Susan L Hietala", "C P Tigges", "Christopher W Dyck" ], "corpus_id": 38222520, "doc_id": "38222520", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "Failure analysis of radio frequency (rf) micro electro mechanical systems (MEMS)", "venue": "SPIE MOEMS MEMS", "year": 2001 }, { "abstract": "Self heating in electrostatically actuated RF MEM capacitive shunt switches is analyzed by coupled electrical and thermal simulations using three dimensional finite element analysis. The result shows that despite highly nonuniform current and temperature distributions, the self heating effect can be approximated by lumped thermal resistances of the switch membrane and the substrate. Additionally, since the thermal resistance of thermally insulating substrates such as quartz is significant compared to that of the membrane, it is important to consider the heat transfer across both the membrane and the substrate.", "author_names": [ "F Solazzi", "Cristiano Palego", "Subrata Halder", "James C M Hwang", "Alessandro Faes", "Viviana Mulloni", "Benno Margesin", "P Farinelli", "Roberto Sorrentino" ], "corpus_id": 34137307, "doc_id": "34137307", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Electro thermal analysis of RF MEM capacitive switches for high power applications", "venue": "2010 Proceedings of the European Solid State Device Research Conference", "year": 2010 }, { "abstract": "Micro electro mechanical sensor systems (MEMS Sensors) are being considered for a variety of applications in space and launch operations. These applications include health and status monitoring, environmental monitoring, automated control, repair and service. A microaccelerometer performance was characterized in detail and their failure mechanisms were identified by subjecting them to 1,000 thermal cycles under extreme temperatures 65 to +150degC) and to 30,000 shocks at 2,000 g. In addition, several other MEMS sensors (microaccelerometers and temperature sensors) were characterized at the extremes of their temperature ranges. It consists of a 10 day test that subjected various microaccelerometers to both continuous thermal cycling between temperatures of 40 degC and +85 degC and mechanical loading. A comparison of the data from microaccelerometers of the same type and between several types will be presented. Self test output signals and X ray evaluation test data after completion of 182 thermal cycles will also be presented.", "author_names": [ "Reza Ghaffarian", "David G Sutton", "Paul D Chaffee", "N Marquez" ], "corpus_id": 9471082, "doc_id": "9471082", "n_citations": 6, "n_key_citations": 1, "score": 0, "title": "Thermal and Mechanical Reliability of Five COTS MEMS Accelerometers", "venue": "", "year": 2002 } ]

[ { "abstract": "Degradation leading to failure in photovoltaic modules follows a progression that is dependent on multiple factors, some of which interact causing degradation that is difficult to simulate in the lab. This paper defines observed degradation in field aged modules, including degradation of packaging materials, adhesional loss, degradation of interconnects, degradation due to moisture intrusion, and semiconductor device degradation. Additionally, this paper suggests that the onset and progression of degradation need to be studied to gain a more comprehensive understanding of module degradation rates and module failures.", "author_names": [ "Michael A Quintana", "David L King", "Thomas Joseph Mcmahon", "Carl R Osterwald" ], "corpus_id": 110543550, "doc_id": "110543550", "n_citations": 268, "n_key_citations": 12, "score": 1, "title": "Commonly observed degradation in field aged photovoltaic modules", "venue": "Conference Record of the Twenty Ninth IEEE Photovoltaic Specialists Conference, 2002.", "year": 2002 }, { "abstract": "Abstract Delamination and discoloration are the most commonly observed encapsulant degradations in crystalline silicon photovoltaic (PV) modules under field conditions. In this work, a comparative analysis of brown discoloration and front side grey appearing delamination of ethylene vinyl acetate (EVA) has been presented, to understand their basic effects and modes of degradation. For this purpose, both type of degraded EVA samples from field aged PV modules have been investigated, for finding the difference in their spectral response, chemical constituents, structural change, and impact on module electrical performance. These investigations have been performed using quantum efficiency (QE) measurement, Fourier transform infrared (FTIR) spectroscopy, X ray diffraction (XRD) and scanning electron microscopy (SEM) In addition, electrical analysis was performed using PSpice circuit simulator. The distinct effect of discolored and delaminated EVA degradations, on incident radiations was identified mainly in absorption and reflection loss respectively, under different wavelengths. Also, the impact of these degradations on module performance, due to mismatch loss within the module has been presented. The chemical constituent investigation, supported presence of delamination in grey degraded sample due to absence of interfacial adhesive agent, in contrast to discolored sample. Findings from the structural investigation, corroborated a decrease in crystalline behaviour of both degradations. Furthermore, impressions from etched silicon cell were observed only in delaminated sample, which can be the reason of its grey appearance and more reflection. This work highlights the comparative effects and impact of dominant EVA degradations in terms of their characteristic aspects, which can be instrumental in improvement of EVA formulation.", "author_names": [ "Roop Singh Meena", "Sagarika Kumar", "Rajesh Gupta" ], "corpus_id": 218966710, "doc_id": "218966710", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Comparative investigation and analysis of delaminated and discolored encapsulant degradation in crystalline silicon photovoltaic modules", "venue": "", "year": 2020 }, { "abstract": "Degradation is commonly observed in field aged PV modules due to corrosion of the photovoltaic ribbon. The reduced performance is caused by a loss of fill factor due to the high series resistance in the PV ribbon. This study aimed to mitigate the degradation by corrosion using five sacrificial anodes Al, Zn and their alloys to identify the most effective material to mitigate the corrosion of the PV ribbon. The corrosion behavior of the five sacrificial anode materials were examined by open circuit potential measurements, potentiodynamic polarization tests, and galvanic current density and potential measurements using a zero resistance ammeter. Immersion tests for 120 hours were also conducted using materials and damp heat test tests were performed for 1500 hours using 4 cell mini modules. The Al 3Mg and Al 3Zn 1Mg sacrificial anodes had a low corrosion rate and reduced drop in power, making then suitable for long term use. yo yag taeyanggwang modyuleseo taeyangjeonjireul yeongyeolhaejuneun inteokeonegteoro ribon soldeoro SnPbAgga sayongdoego, ogoe taeyanggwang baljeone janggigan noculsi ribonyi busigeuro inhan yeolhwaga heunhi gwancaldoenda. ireohan busighyeonsangeuro inhayeo ribongwa taeyangjeonjiyi jeobhabi yaghaejyeo jeobcogjeo hangi jeunggahago, ddohan ribon jaceyi jigryeol jeohangi jeunggahage doeeo taeyangjeonjiyi jeonab jeonryu gogseoneseo cungjinryul sonsilro culryeogi jeohadoen da. bon nonmuneseoneun ribonyi busigeul wanhwasikil su issneun bangbeobeuro hyisaengyanggeugbeobeul iyonghayeo sunsu alruminyum mic ayeon, alruminyum, ayeon geurigo mageunesyumyi habgeumeul iyonghan 5gaji hyisaengyanggeug sojaeyi busige yihan yeolhwa jeogameul yeonguhayeossda. jeongihwahagjeog bangbeobeuro hyisaengyang geug sojaeyi gaebanghoero jeonwiwa pyeswaehoero jeonwireul ceugjeonghayeossgo, potensiodainamig bungeug gogseoneul ceugjeonghago, yeongjeohangjeonryugyereul iyonghayeo ribongwa sojaeganyi galbanig jeonryureul ceugjeonghayeossda. ddohan, aseteusangwa, NaCle ribongwa hyisaengyanggeug sojaeyi bucag jeonhuyi cimjisiheomgwa 4sel minimodyulro jejaghan hu 1500sigan goongoseub siheom jeonhu culryeogeul pyeonggahayeossda. geu gyeolgwa Al 3Mgwa Al 3Zn 1Mgyi hyisaengyanggeug sojaega busigsogdoga neurigo, culryeogjeohareul jeogamsikil bbunman anira janggi anjeongseongedo hyogwajeogin geoseuro pyeonggadoenda.", "author_names": [ "Wonwook Oh", "S I Chan" ], "corpus_id": 201911780, "doc_id": "201911780", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Corrosion mitigation of photovoltaic ribbon using a sacrificial anode", "venue": "", "year": 2017 }, { "abstract": "To identify the common degradation mechanism(s) between field aged photovoltaic (PV) modules and PV cells/modules exposed to artificial corrosive stress, the ac impedance associated with the corrosion in the front electrodes was analyzed in the individual PV cells laminated within the PV modules, fielded for 21 years. By evaluating the ac impedance together with the PV performance for these PV cells, we found that the short circuit current (Isc) remarkably decreased, depending on the expression and elevation of the ac impedance relevant to the front electrode corrosion. This Isc reduction can be explained by the formation of rectifying contacts to restrict the current conduction between the front electrodes and the associated silicon wafer. Since the Isc reduction was primarily observed in the PV cells with extensive loss of fill factor, we suggest that the power loss is induced by the gap formation underneath the front electrodes, followed by the emergence of rectifying contacts, even in the PV cells/modules degraded in field. The ac impedance parameters of the PV cells/modules could be a valuable predictor of the service lifetime of PV modules, as our findings in this study mean the equivalency of the failure attained by extended damp heat testing with that observed in the field.", "author_names": [ "Tadanori Tanahashi", "Norihiko Sakamoton", "Hajime Shibata", "Atsushi Masuda" ], "corpus_id": 127433401, "doc_id": "127433401", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Corrosion Induced AC Impedance Elevation in Front Electrodes of Crystalline Silicon Photovoltaic Cells Within Field Aged Photovoltaic Modules", "venue": "IEEE Journal of Photovoltaics", "year": 2019 }, { "abstract": "Ethylene vinyl acetate (EVA) is the predominant encapsulant in crystalline silicon photovoltaic (PV) modules; however, its degradation is a subject of major concern, which causes significant power loss under field conditions. This article presents a comparison of EVA degradation in field aged PV modules with glass/backsheet (G/B) and glass/glass (G/G) architectures. Module level characterization included UV fluorescence imaging and I V measurements. Material analytical techniques, including colorimetry, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Raman spectroscopy, were performed to correlate the module performance parameters with EVA material properties. An intense EVA discoloration in G/G modules was observed, which was corroborated by higher module $I_{sc} and Pmax degradation rates compared with its counterpart G/B modules. Higher power degradation was accompanied by a significant increase in EVA crosslinking, vinyl acetate content, yellowness index, and presence of functional groups containing unsaturated moieties that are linked to degradation products of photothermal reaction, and a higher decrease in the degree of crystallinity. The absence of a polymeric backsheet in hermetically sealed G/G modules, which restricts photobleaching and enhances the entrapment of volatile acetic acid and other degradation by products, plays a major role in causing higher EVA degradation in G/G modules. This article concludes that EVA might have been a good choice of an encapsulant for the G/B modules over the decades, but it may prove to be an inappropriate choice for the G/G modules because of potential degassing, corrosion, and/or discoloration issues. Ionomers or polyester based encapsulants like polyolefins could be best suited for G/G modules as it appears to be a current trend in the industry.", "author_names": [ "Aesha Parimalbhai Patel", "Archana Sinha", "Govindasamy Tamizhmani" ], "corpus_id": 211243492, "doc_id": "211243492", "n_citations": 5, "n_key_citations": 1, "score": 0, "title": "Field Aged Glass/Backsheet and Glass/Glass PV Modules: Encapsulant Degradation Comparison", "venue": "IEEE Journal of Photovoltaics", "year": 2020 }, { "abstract": "Degradation phenomena observed in field aged crystalline silicon photovoltaic modules include EVA browning, delamination between the glass encapsulant and the cell encapsulant interfaces, degradation of the anti reflective coating, corrosion of busbars and contacts, cracks, humidity ingress, etc. The type and severity of the defects observed vary significantly between cells, modules and installations as affected by a number of both internal and external parameters. This study presents mild to severe degradation effects observed in crystalline silicon PV modules operating outdoors for different periods of time and investigated through non destructive testing techniques including I V characterisation, UV fluorescence, IR thermography and Electroluminescence (EL) Imaging. The identification and diagnosis of defects and further correlation to the electrical degradation of the module is achieved through the complementary contribution of these techniques. Severe electrical degradation and mismatch between the cells are identified through IR thermography and EL imaging. Diagnosis of rather uniformly degraded modules is enhanced through EL Imaging by which shunts, higher resistance regions, cracks, broken metallization are identified, while the module may appear to operate reliably. Signs of early degradation are further diagnosed through UV fluorescence and EL Imaging, allowing to monitor the evolution of defects and evaluate module reliability.", "author_names": [ "Eleni Kaplani" ], "corpus_id": 59149700, "doc_id": "59149700", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "Degradation in Field aged Crystalline Silicon Photovoltaic Modules and Diagnosis using Electroluminescence Imaging", "venue": "", "year": 2016 }, { "abstract": "The longevity of solar photovoltaic modules depends on the durability and reliability of their components, one of which is the solder bonds in interconnect ribbons. The solder joints experience stresses from thermal cycling and constant elevated temperatures (40 degC 70 degC) in regular field operation leading to thermo mechanical fatigue and intermetallic compound formation. To study the end of life wear out mechanisms and to obtain activation energy of solder bond degradation, two field aged modules from Arizona a 21 year old Solarex MSX60 module (with Sn62Pb36Ag2 at the solder joints) and an 18 year old Siemens M55 module (with Sn60Pb40 at the solder joints) underwent 800 and 400 modified thermal cycles, respectively. Using three heating blankets, each module had three temperature zones maintained at 85, 95, and 105 degC during the 15 min hot dwell time of the thermal cycle. Cell level series resistance data obtained from three temperature zones enabled the calculation of activation energy for solder bond degradation for the MSX60 and the M55 modules to be 0.12 eV and 0.35 eV, respectively. From each temperature zone in both modules, busbar solder samples were obtained, imaged through SEM, and analyzed with energy dispersive X ray spectroscopy. In the MSX60 module with traces of Ag in the solder material, phase segregation and growth were primarily observed at high temperatures. For M55 modules without Ag in the solder material, major phase segregation was observed in all temperature zones. The IMC thickness for both modules increased with increasing module temperature. The beneficial effect of Ag in solder material on mitigating solder bond degradation is presented.", "author_names": [ "Hamsini Gopalakrishna", "Archana Sinha", "Joe Carpenter", "Sridhar Niverty", "Nikhilesh Chawla", "Dirk C Jordan", "Govindasamy Tamizhmani" ], "corpus_id": 225048360, "doc_id": "225048360", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Activation Energy for End of Life Solder Bond Degradation: Thermal Cycling of Field Aged PV Modules", "venue": "IEEE Journal of Photovoltaics", "year": 2020 }, { "abstract": "Encapsulant discoloration, a commonly occurring and serious field degradation mode, can be replicated by exposing modules to UV light. Increasing the UV light intensity and the testing temperatures reduces the required testing time. Calculating activation energy using Arrhenius equation for the encapsulant discoloration requires short circuit current data (or yellowness index data) at multiple temperatures over significant time period. A method of simultaneously obtaining four temperatures in four photovoltaic modules in a single walk in accelerated UV weathering chamber which drastically reduces the required time and resources is presented. Field aged modules with visible encapsulant browning were selected for the accelerated testing to determine the wear out failure mechanisms rather than the early life and midlife failure mechanisms conventionally determined using fresh modules. These modules have been subjected to a very long UV exposure of 450 kWh operating at high temperatures. This work demonstrates that a fast, repeatable, and non contact UV fluorescence setup can be used in the accelerated testing programs and in powerplants as a standardized technique for an early encapsulant browning detection.", "author_names": [ "Hamsini Gopalakrishna", "Archana Sinha", "Jaewon Oh", "Kshitiz Dolia", "Sai Ravi Tatapudi", "Govindasamy Tamizhmani" ], "corpus_id": 54439524, "doc_id": "54439524", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Novel Accelerated UV Testing of Field Aged Modules: Correlating EL and UV Fluorescence Images with Current Drop", "venue": "2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC 34th EU PVSEC)", "year": 2018 }, { "abstract": "In this paper, degradation in field aged PV modules including degradation of interconnect, discoloration of encapsulant and hot spot have been observed and analyzed. From the results, photovoltaic module installed for 6 years shows around 16 drop of electrical properties due to the interconnect degradation and PV module passed 18 years has been found to drop of around 20 mainly by the encapsulant discoloration. Furthermore the difference between low and high temperature of PV array at hot spot goes up to 3 and it leads to interconnect degradation. On the other hands, the temperature difference was observed to be around 15 at the encapsulant discoloration spot of PV array.", "author_names": [ "Gihwan Kang", "Gwonjong Yu", "Hyung-Keun Ahn", "Deukyoung Han" ], "corpus_id": 137693207, "doc_id": "137693207", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Consideration of Electrical Properties in Field aged Photovoltaic Module", "venue": "", "year": 2004 }, { "abstract": "Due to the vast expansion of photovoltaic (PV) module production nowadays, a great interest is shown in factors affecting PV performance and efficiency under real conditions. Particular attention is being given to degradation effects of PV cells and modules, which during the last decade are seen to be responsible for significant power losses observed in PV systems. This paper presents and analyses degradation effects observed in severely EVA discoloured PV cells from field aged modules operating already for 18 22 years. Temperature degradation effects are identified through IR thermography in bus bars, contact solder bonds, blisters, hot spots, and hot areas. I V curve analysis results showed an agreement between the source of electrical performance degradation and the degradation effects in the defected cell identified by the IR thermography. Finally, an algorithm was developed to automatically detect EVA discoloration in PV cells through processing of the digital image alone in a way closely imitating human perception of color. This nondestructive and noncostly solution could be applied in the detection of EVA discoloration in existing PV installations and the automatic monitoring and remote inspection of PV systems.", "author_names": [ "Eleni Kaplani" ], "corpus_id": 56565327, "doc_id": "56565327", "n_citations": 107, "n_key_citations": 3, "score": 0, "title": "Detection of Degradation Effects in Field Aged c Si Solar Cells through IR Thermography and Digital Image Processing", "venue": "", "year": 2012 } ]

[ { "abstract": "Colloidal quantum rods of cadmium selenide (CdSe) exhibit linearly polarized emission. Empirical pseudopotential calculations predict that slightly elongated CdSe nanocrystals have polarized emission along the long axis, unlike spherical dots, which emit plane polarized light. Single molecule luminescence spectroscopy measurements on CdSe quantum rods with an aspect ratio between 1 and 30 confirm a sharp transition from nonpolarized to purely linearly polarized emission at an aspect ratio of 2. Linearly polarized luminescent chromophores are highly desirable in a variety of applications.", "author_names": [ "Jiangtao Hu", "Liang-shi Li", "Weidong Yang", "Liberato Manna", "Lin-wang Wang", "A Paul Alivisatos" ], "corpus_id": 45130871, "doc_id": "45130871", "n_citations": 926, "n_key_citations": 5, "score": 1, "title": "Linearly Polarized Emission from Colloidal Semiconductor Quantum Rods", "venue": "Science", "year": 2001 }, { "abstract": "Quasi one dimensional (1D) semiconductor nanocrystals manifest linearly polarized emission, reduced lasing threshold, and improved charge transport compared with their counterparts such as spherical quantum dots. Present investigations of colloidal semiconductor quantum rods are mainly based on cadmium chalcogenide systems because of their facile synthetic accessibility. However, it is still a big challenge to fabricate quasi 1D zinc chalcogenide nanocrystals with controlled aspect ratios. Here we report a general strategy for synthesizing zinc chalcogenide quantum rods via a colloidal chemical synthetic approach. Unlike the most common growth mechanisms of quasi 1D colloidal nanocrystals such as monomer attachment and particle coalescence, the synthesis of zinc chalcogenide quantum rods is performed by a ripening process starting from their respective ultrathin nanowires through thermodynamically driven material diffusion. We anticipate that this strategy is general and could be applied to other systems to construct quasi 1D nanostructures. Moreover, the presence of cadmium free (or \"green\" zinc chalcogenide quantum rods synthesized through this strategy provides a desirable platform for eco friendly photocatalysis, optoelectronic devices, biolabeling, and other applications.", "author_names": [ "Guohua Jia", "Uri Banin" ], "corpus_id": 10440636, "doc_id": "10440636", "n_citations": 52, "n_key_citations": 0, "score": 0, "title": "A general strategy for synthesizing colloidal semiconductor zinc chalcogenide quantum rods.", "venue": "Journal of the American Chemical Society", "year": 2014 }, { "abstract": "Colloidal semiconductor nanocrystals, also known as \"quantum dots\" (QDs) represent an example of a disruptive technology for display and lighting applications. Their high luminescence efficiency and tunable, narrow emission are nearly ideal for achieving saturated colors and enriching the display or TV color gamut. Our contribution will discuss the next generation of inorganic nanostructures with electronic structure optimized for achieving emission characteristics beyond traditional near spherical QDs. For example, nano heterostructures with spherical CdSe QDs epitaxially integrated into CdS quantum rods combine high luminescence efficiency with giant extinction coefficients, large Stokes shifts, and linearly polarized emission. Such a set of characteristics can be ideal for LCD backlighting. The other class of emitters includes colloidal quantum wells (QWs) whose ensemble luminescence is significantly narrower than emission spectra of the best QD samples. Moreover, we show that colloidal QWs produce amplified spontaneous emission (ASE) with pump fluence thresholds as low as 6 mJ/cm2 and gain as high as 600 cm 1, on par with the best values for any solution processed material.", "author_names": [ "Chunxing She", "Igor Fedin", "Michael A Boles", "Dmitriy S Dolzhnikov", "Richard D Schaller", "Matthew Pelton", "Dmitri V Talapin" ], "corpus_id": 135544336, "doc_id": "135544336", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "12.2: Invited Paper: Colloidal Quantum Rods and Wells for Lighting and Lasing Applications", "venue": "", "year": 2014 }, { "abstract": "Atomically thin layers of transition metal dichalcogenides semiconductors, such as MoS2, exhibit strong and circularly polarized light emission due to inherent crystal symmetries, pronounced spin orbit coupling and out of plane dielectric and spatialconfinement. While the layer by layer confinement is well understood, the impact of in plane quantization in their optical spectrum is far behind. Here, we report the novel optical properties of atomically thin MoS2 colloidal semiconductor nanocrystals. Besides the spatial confinement effect leading to their blue wavelength emission, the high quality of our MoS2 nanocrystals is revealed by narrow photoluminescence, which allows us to resolve multiple optically active transitions, originating from quantum confined excitons (coupled electron hole pairs) Surprisingly, in stark contrast to monolayer MoS2, the luminescence of the lowest energy levels is linearly polarized and persists up to room temperature that could be exploited in a variety of light emitting applications.", "author_names": [ "Andres Granados del Aguila", "Sheng Liu", "T Anh Thu Do", "Zhuangchai Lai", "Thu Ha Tran", "Sean Ryan Krupp", "Zhi-Rui Gong", "Hua Zhang", "Wang Yao", "Qihua Xiong" ], "corpus_id": 203639974, "doc_id": "203639974", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Linearly Polarized Luminescence of Atomically Thin MoS2 Semiconductor Nanocrystals.", "venue": "ACS nano", "year": 2019 }, { "abstract": "Spectroscopy of single colloidal quantum dots (QDs) especially at cryogenic temperature, helps to understand the inherent properties of nanocrystals that are often hidden in ensemble level studies. This applies in particular to InP based QDs, which attract increasing interest as Cd free alternative nanocrystals yet were hardly investigated at the single QD level. Here, we discuss the photoluminescence properties of single InP/ZnSe QDs, both at room temperature and at cryogenic temperature. While ensemble level measurements feature a luminescent linewidth of around 50 nm, we find that emission spectrum of single InP/ZnSe QDs can have a linewidth as narrow as 14 nm (50 meV) Hence, the relatively broad emission line that characterizes ensembles of InP based QDs is by no means an intrinsic material property. In addition, we found that InP/ZnSe QDs combine a nearly blinking free emission with a high purity single photon emission (g(0)<0.03) also well beyond the saturation intensity.[1] Cryogenic single QD spectra, on the other hand, consist of zero phonon lines that can be as narrow as 40 meV. Polarization resolved spectra point to a linearly polarized spectral doublet from the bright exciton. At lower excitation intensities, jitter was negligible and spectra could be integrated for tens of seconds without erasing the doublet splitting of 1.2 meV. At higher excitation intensities, jitter becomes more severe and switching between emission from the exciton doublet and the trion singlet can be observed. This indicates that spectral jitter finds its origin in changes of the local electric field caused by the temporal trapping of one charge carrier. In summary, we find conclude that single InP QDs have emission characteristics similar to the extensively studied CdSe based QDs. Moreover, the narrow emission lines, limited jitter and fluorescence intermittency of single InP/ZnSe QDs holds great promise to further explore these materials as a solutionprocessable single photon emitter and improve the ensemble level characteristics of these materials.", "author_names": [ "Vigneshwaran Chandrasekaran", "Lorenzo Scarpelli", "Francesco Masia", "Dorian Dupont", "Mickael D Tessier", "Pieter Geiregat", "Iwan Moreels", "Wolgang Langbein", "Zeger Hens" ], "corpus_id": 106025698, "doc_id": "106025698", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Spectral dynamics of linearly polarized bright exciton in InP/ZnSe colloidal quantum dots", "venue": "", "year": 2018 }, { "abstract": "Polarizers provide convenience in generating polarized light, meanwhile their adoption raises problems of extra weight, cost, and energy loss. Aiming to realize polarizer free polarized light sources, herein, we present a plasmonic approach to achieve direct generation of linearly polarized optical waves at the nanometer scale. Periodic slot nanoantenna arrays are fabricated, which are driven by the transition dipole moments of luminescent semiconductor quantum dots. By harnessing interactions between quantum dots and scattered fields from the nanoantennas, spontaneous emission with a high degree of linear polarization is achieved from such hybrid antenna system with polarization perpendicular to antenna slot. We also demonstrate that the polarization is engineerable in aspects of both spectrum and magnitude by tailoring plasmonic resonance of the antenna arrays. Our findings will establish a basis for the development of innovative polarized light emitting devices, which are useful in optical displays, spectroscopic techniques, optical telecommunications, and so forth.", "author_names": [ "Mengxin Ren", "Mo Chen", "Wei Wu", "Lihui Zhang", "Junku Liu", "Biao Pi", "Xinzheng Zhang", "Qunqing Li", "Shoushan Fan", "Jingjun Xu" ], "corpus_id": 30737229, "doc_id": "30737229", "n_citations": 36, "n_key_citations": 0, "score": 0, "title": "Linearly polarized light emission from quantum dots with plasmonic nanoantenna arrays.", "venue": "Nano letters", "year": 2015 }, { "abstract": "Semiconductor heterostructure nanocrystals, especially with core/shell architectures, are important for numerous applications. Here we show that by decreasing the shell growth rate the morphology of ZnS shells on ZnSe quantum rods can be tuned from flat to islands like, which decreases the interfacial strain energy. Further reduced growth speed, approaching the thermodynamic limit, leads to coherent shell growth forming unique helical shell morphology. This reveals a template free mechanism for induced chirality at the nanoscale. The helical morphology minimizes the sum of the strain and surface energy and maintains band gap emission due to its coherent core/shell interface without traps, unlike the other morphologies. Reaching the thermodynamic controlled growth regime for colloidal semiconductor core/shell nanocrystals thus offers morphologies with clear impact on their applicative potential.Core/shell semiconductor nanocrystals have advantageous optoelectronic properties, which depend on the shell architecture. Here the authors show that by reducing the growth rate of ZnS shells on ZnSe nanorods the shell morphology can be tuned from flat to islands like to helical", "author_names": [ "Botao Ji", "Yossef E Panfil", "Nir Waiskopf", "Sergei Remennik", "Inna Popov", "Uri Banin" ], "corpus_id": 57373569, "doc_id": "57373569", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "Strain controlled shell morphology on quantum rods", "venue": "Nature Communications", "year": 2019 }, { "abstract": "Semiconductor quantum dots (QDs) have been demonstrated viable for the emission of single photons on demand during the past decade. However, the synthesis of QDs emitting photons with pre defined a", "author_names": [ "Anders Lundskog", "Chih-Wei Hsu", "K F Karlsson", "Supaluck Amloy", "Daniel Nilsson", "Urban Forsberg", "P O Holtz", "Erik Janzen" ], "corpus_id": 123117625, "doc_id": "123117625", "n_citations": 60, "n_key_citations": 2, "score": 0, "title": "Direct generation of linearly polarized photon emission with designated orientations from site controlled InGaN quantum dots", "venue": "", "year": 2014 }, { "abstract": "The polarized emission of colloidal quantum dots from II VI and perovskite semiconductors were investigated thoroughly, revealing information about the optical transitions in these materials and their potential use in various opto electronic or spintronic applications. The studies included recording of the micro photoluminescence of individual nanostructures at cryogenic temperatures, with or without the influence of an external magnetic field. The experimental conditions enabled detection of circular and/or linear polarized emission to elucidate the exciton manifolds, angular momentum of the emitting states, Lande g factors, single exciton and bi exciton binding energies, the excitons' effective Bohr radii, and the unique influence of the Rashba effect. The study advances the understanding of other phenomena such as electron hole dissociation, long diffusion lengths, and spin coherence, facilitating appropriate design of optical and spin based devices.", "author_names": [ "Maya Isarov", "Liang Z Tan", "Jenya Tilchin", "Freddy T Rabouw", "Maryna I Bodnarchuk", "Relinde J A van Dijk-Moes", "R Carmi", "Yahel Barak", "Alyssa Kostadinov", "Itay Meir", "Daniel Vanmaekelbergh", "Maksym V Kovalenko", "Andrew M Rappe", "Efrat Lifshitz" ], "corpus_id": 3903834, "doc_id": "3903834", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Polarized emission in II VI and perovskite colloidal quantum dots", "venue": "", "year": 2017 }, { "abstract": "Semiconductor nanorods can emit linear polarized light at efficiencies over 80% Polarization of light in these systems, confirmed through single rod spectroscopy, can be explained on the basis of the anisotropy of the transition dipole moment and dielectric confinement effects. Here we report emission polarization in macroscopic semiconductor polymer composite films containing CdSe/CdS nanorods and colloidal CdSe nanoplatelets. Anisotropic nanocrystals dispersed in polymer films of poly butyl co isobutyl methacrylate (PBiBMA) can be stretched mechanically in order to obtain unidirectionally aligned arrays. A high degree of alignment, corresponding to an orientation factor of 0.87, was achieved and large areas demonstrated polarized emission, with the contrast ratio I/I 5.6, making these films viable candidates for use in liquid crystal display (LCD) devices. To some surprise, we observed significant optical anisotropy and emission polarization for 2D CdSe nanoplatelets with the electronic structure of quantum wells. The aligned nanorod arrays serve as optical funnels, absorbing unpolarized light and re emitting light from deep green to red with quantum efficiencies over 90% and high degree of linear polarization. Our results conclusively demonstrate the benefits of anisotropic nanostructures for LCD backlighting. The polymer films with aligned CdSe/CdS dot in rod and rod in rod nanostructures show more than 2 fold enhancement of brightness compared to the emitter layers with randomly oriented nanostructures. This effect can be explained as the combination of linearly polarized luminescence and directional emission from individual nanostructures.", "author_names": [ "Patrick D Cunningham", "Joao B Souza", "Igor Fedin", "Chunxing She", "Byeongdu Lee", "Dmitri V Talapin" ], "corpus_id": 206699645, "doc_id": "206699645", "n_citations": 123, "n_key_citations": 1, "score": 0, "title": "Assessment of Anisotropic Semiconductor Nanorod and Nanoplatelet Heterostructures with Polarized Emission for Liquid Crystal Display Technology.", "venue": "ACS nano", "year": 2016 } ]

[ { "abstract": "", "author_names": [ "Henan Li", "Jing-Kai Huang", "Yumeng Shi", "Lain-Jong Li" ], "corpus_id": 198384144, "doc_id": "198384144", "n_citations": 17, "n_key_citations": 0, "score": 2, "title": "Toward the Growth of High Mobility 2D Transition Metal Dichalcogenide Semiconductors", "venue": "Advanced Materials Interfaces", "year": 2019 }, { "abstract": "We give here an overview on our results on the large area growth of 2D transition metal dichalcogenide semiconductors MoS₂ MoSe₂ WSe₂ using chemical vapor deposition. The growth of MoS₂ on sapphire occurs epitaxially with the crystalline orientation of the MoS₂ film closely matching that of the sapphire substrate, resulting in a high quality continuous film. The use of H₂S results in more control over growth morphologies. WSe₂ and MoSe₂ have also been successfully grown using solid state precursors. Room temperature mobilities of all these materials exceed 10 cm²V¹s¹ In contrast to MoS₂ WSe₂ and MoSe₂ show ambipolar behavior.", "author_names": [ "Dumitru Dumcenco", "Dmitry Ovchinnikov", "Kolyo Marinov", "Andras Kis" ], "corpus_id": 13098654, "doc_id": "13098654", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "High quality synthetic 2D transition metal dichalcogenide semiconductors", "venue": "2016 46th European Solid State Device Research Conference (ESSDERC)", "year": 2016 }, { "abstract": "Transition metal dichalcogenides (TMDs) have previously been recognized as a new class of semiconducting 2D layered materials.1, 2 TMDs such as molybdenum disulfide (MoS2) and tungsten diselenide (WSe2) thus open up new opportunities in semiconductor technology for the development of future 2D electronics and optoelectronics. Furthermore, monolayer TMDs feature a direct energy band gap, good carrier mobility, and excellent 'on''off' current ratios when they are fabricated in field effect transistors. These are all advantageous properties for future low power electronic and optoelectronic devices. To achieve additional applications of these materials in advanced circuits, however, it is necessary to develop a 2D p n junction (i.e. the interface between a p type and an n type semiconductor) In earlier studies of such p n junctions, the focus has mainly been on vertically stacked van der Waals heterojunctions in which the interface properties and stacking angle strongly affect the junction performance.3, 4 Alternatively, it has been shown that chemical vapor deposition (CVD) can be used reliably for the growth of wafer scale 2D materials and is feasible for lateral heterojunction growth.5 The thermodynamically favored formation of TMD alloys at the hetero interface during the so called one pot synthetic process, however, remains an obstacle to the formation of lateral heterojunctions via direct CVD growth.6 8 Moreover, the one pot synthetic process only allows the growth of heterostructures with either different metals or different chalcogens, and this limits the materials that can be selected for practical applications.6 8 To provide a more reliable and robust growth method for 2D heterojunctions, we have therefore developed a new Figure 1. (a) Optical microscope image of the tungsten diselenide/ molybdenum disulfide (WSe2/MoS2) lateral heterojunction fabricated using the two step epitaxial growth method. (b) A high resolution scanning transmission electron microscope image of the heterojunction, showing the atomically sharp interface between the WSe2 and the MoS2.", "author_names": [ "Lain-Jong Li", "Ming-Yang Li" ], "corpus_id": 124307380, "doc_id": "124307380", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Epitaxial growth of a 2D transition metal dichalcogenide lateral heterojunction", "venue": "", "year": 2016 }, { "abstract": "Two dimensional (2D) heterostructures based on layered transition metal dichalcogenides (TMDs) have attracted increasing attention for the applications of the next generation high performance integrated electronics and optoelectronics. Although various TMD heterostructures have been successfully fabricated, epitaxial growth of such atomically thin metal semiconductor heterostructures with a clean and sharp interface is still challenging. In addition, photodetectors based on such heterostructures have seldom been studied. Here, we report the synthesis of high quality vertical NbS2/MoS2 metallic semiconductor heterostructures. By using NbS2 as the contact electrodes, the field effect mobility and current on off ratio of MoS2 can be improved at least 6 fold and two orders of magnitude compared with the conventional Ti/Au contact, respectively. By using NbS2 as contact, the photodetector performance of MoS2 is much improved with higher responsivity and less response time. Such facile synthesis of atomically thin metal semiconductor heterostructures by a simple chemical vapor deposition strategy and its effectiveness as ultrathin 2D metal contact open the door for the future application of electronics and optoelectronics.", "author_names": [ "P Zhang", "Ce Bian", "Jiafu Ye", "Ningyan Cheng", "Xiao Wang", "Huaning Jiang", "Yi Wei", "Yiwei Zhang", "Yi Du", "Lihong Bao", "Weida Hu", "Yongji Gong" ], "corpus_id": 220071773, "doc_id": "220071773", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Epitaxial growth of metal semiconductor van der Waals heterostructures NbS2/MoS2 with enhanced performance of transistors and photodetectors", "venue": "Science China Materials", "year": 2020 }, { "abstract": "Two dimensional (2D) layered semiconductors are emerging as promising candidates for next generation thin film electronics because of their high mobility, relatively large bandgap, low power switching, and the availability of large area growth methods. Thin film transistors (TFTs) based on multilayer transition metal dichalcogenides or black phosphorus offer unique opportunities for next generation electronic and optoelectronic devices. Here, we review recent progress in high mobility transistors based on multilayer 2D semiconductors. We describe the theoretical background on characterizing methods of TFT performance and material properties, followed by their applications in flexible, transparent, and optoelectronic devices. Finally, we highlight some of the methods used in metal semiconductor contacts, hybrid structures, heterostructures, and chemical doping to improve device performance.", "author_names": [ "Zhenxing Wang", "Amber McCreary", "Natalie Briggs", "Joice Sophia Ponraj", "Zai-Quan Xu", "Sathish Chander Dhanabalan", "Seong Yeoul" ], "corpus_id": 13849716, "doc_id": "13849716", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Recent progress in high mobility thin film transistors based on multilayer 2 D materials", "venue": "", "year": 2017 }, { "abstract": "Heterostructures based on two dimensional (2D) transition metal dichalcogenides semiconductors are reported to be promising building blocks for next generation integrated optoelectronic systems, owing to their atomic thin interface and interface induced properties. Previously reported works have mostly been directed to focus on the 2D/2D heterostructures, and their optoelectronic performance is still inferior to the expectations for practical applications, mainly attributed to their non ideal optical absorption when the thickness is confined at atomic scale. In this work, we have reported on high sensitivity photodetectors based on one dimensional (1D)/2D heterostructures consisting of CdS nanowire and WS2 nanosheets grown by direct chemical vapor deposition. The components of the heterostructures were confirmed by x ray diffraction, x ray photoelectron spectroscopy, transmission electron microscope, photoluminescence and Raman spectra measurements, confirming the high quality heterostructures. Photodetectors were then fabricated based on the as synthesized CdS/WS2 heterostructures, showing superior photodetection performances with a photoresponsivity of ~50 A W 1 and an ultrahigh photodetectivity of ~1012 Jones. Much higher responsivity of 5472 A W 1 and detectivity of 5 x 1013 Jones can be achieved through applying back gate voltage. The direct growth of such 1D/2D heterostructures may pave the way toward high performance integrated optoelectronics and systems.", "author_names": [ "Anlian Pan" ], "corpus_id": 145022388, "doc_id": "145022388", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Vapor growth of CdS nanowires/WS2 nanosheet heterostructures with sensitive photodetections.", "venue": "Nanotechnology", "year": 2019 }, { "abstract": "Two dimensional (2D) nanosheets of layered transition metal dichalcogenides (TMDs) have received significant attention because some of them are semiconductors with sizable band gaps and are naturally abundant. Here, we report the photolithographic pattern transfer (PPT) technology used to fabricate FETs of two dimensional materials. To explore the electrical properties and realize functional optoelectronics and electronics from semiconductors, the fabrication of devices (such as field effect transistors (FET) diodes and Hall bars) and integrated circuits is necessary and important. An essential step in fabricating micro /nanoelectronics is making the metal electrode arrays. Such a PPT method can be used to efficiently design and prepare complicated electrode arrays for electronics and optoelectronics, and is especially suitable for 2D materials. Few layer MoS 2 made by electron beam lithography (EBL) gold wire mask moving (GWM) and this method are used as templates for comparison. The mobility of our thin MoS 2 flake is comparable to the results of devices from EBL and better than the results of the GWM method. Further complicated device applications such as a top gate FET, a Hall bar, and heterostructure transistors could also be easily realized based on such a method. We also report the growth and electric transport of Co doped MoS 2 bilayer. As the initial loading of the sulfur increases, the morphology of the Co x Mo 1 x S 2 (0 x <1) nanosheets becomes hexagons from David stars step by step at 680degC. We find that Co atoms mainly distribute at the edge of nanosheets. When the temperature increases from 680 to 750degC, high quality cubic pyrite type crystal structure CoS 2 grows on the surface of Co x Mo 1 x S 2 nanosheet gradually and forms hexagonal film induced by the nanosheet. Electrical transport measurements reveal that the Co x Mo 1 x S 2 nanosheets and CoS 2 films exhibit n type semiconducting transport behavior and half metallic behavior, respectively. Theoretical calculations of their band structures agree well with the experimental results. These alloy nanosheets of Co x Mo 1 x S 2 should have large potential applications in the tunable optoelectronics. Then, we report the vapor phase growth and optoelectronic property of vertical bilayer SnS 2 /MoS 2 heterostructure. 2D van der Waals heterostructures with different types of band alignment have recently attracted great attention due to their unique optical and electrical properties. Most 2D heterostructures are formed by transfer stacking two monolayers together, but the interfacial quality and controllable orientation of such artificial structures are inferior to those epitaxial grown heterostructures. An extremely Type II band alignment exists in this 2D heterostructure, with band offset larger than any other reported. Consistent with the large band offset, distinctive optical properties including strong photoluminescence quenching in the heterostructure area are observed in the heterostructure. The SnS 2 /MoS 2 heterostructures also exhibit well aligned lattice orientation between the two layers, forming a periodic Moire superlattice pattern with high lattice mismatch. Electrical transport and photoresponsive studies demonstrate that the SnS 2 /MoS 2 heterostructures exhibit an obvious photovoltaic effect and possess high on/off ratio >10 6 high mobility (27.6 cm 2 V 1 s 1 and high photoresponsivity (1.36 A W 1 Efficient synthesis of such vertical heterostructure may open up new realms in 2D functional electronics and optoelectronics. Finally we give some perspectives on studies of two dimensional materials in future.", "author_names": [ "Bo Li", "Zhongming Wei" ], "corpus_id": 102941761, "doc_id": "102941761", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Growth and optoelectronic property of two dimensional semiconductors", "venue": "", "year": 2017 }, { "abstract": "Significance Traditional semiconductor fabrication methods, such as lithography and etching, have been sufficient for the needs of integrated circuits over past decades. Their applicability has also been demonstrated in emerging 2D materials, which offers facile processing over large lateral dimensions, while unique and remarkable properties due to the confinement within atomic thicknesses. Nevertheless, each fabrication step adds cost to the manufacturing and increases the possibility of quality degradation. Here, we developed a method to directly synthesize arbitrary monolayer molybdenum disulfide patterns with high spatial resolution, excellent homogeneity, and electrical performance on insulating SiO2/Si. Significantly, our on demand method allows for the repeated growth of patterned 2D materials with preserved structural integrity and material qualities, paving the way for simpler and cost effective fabrication. The 2D van der Waals crystals have shown great promise as potential future electronic materials due to their atomically thin and smooth nature, highly tailorable electronic structure, and mass production compatibility through chemical synthesis. Electronic devices, such as field effect transistors (FETs) from these materials require patterning and fabrication into desired structures. Specifically, the scale up and future development of \"2D\" based electronics will inevitably require large numbers of fabrication steps in the patterning of 2D semiconductors, such as transition metal dichalcogenides (TMDs) This is currently carried out via multiple steps of lithography, etching, and transfer. As 2D devices become more complex (e.g. numerous 2D materials, more layers, specific shapes, etc. the patterning steps can become economically costly and time consuming. Here, we developed a method to directly synthesize a 2D semiconductor, monolayer molybdenum disulfide (MoS2) in arbitrary patterns on insulating SiO2/Si via seed promoted chemical vapor deposition (CVD) and substrate engineering. This method shows the potential of using the prepatterned substrates as a master template for the repeated growth of monolayer MoS2 patterns. Our technique currently produces arbitrary monolayer MoS2 patterns at a spatial resolution of 2 mm with excellent homogeneity and transistor performance (room temperature electron mobility of 30 cm2 V 1 s 1 and on off current ratio of 107) Extending this patterning method to other 2D materials can provide a facile method for the repeatable direct synthesis of 2D materials for future electronics and optoelectronics.", "author_names": [ "Yunfan Guo", "Pin-Chun Shen", "Cong Su", "Ang-Yu Lu", "Marek Hempel", "Yimo Han", "Qingqing Ji", "Yuxuan Lin", "Enzheng Shi", "Elaine McVay", "Letian Dou", "David A Muller", "Tomas Palacios", "Ju Li", "Xi Ling", "Jing Kong" ], "corpus_id": 73450680, "doc_id": "73450680", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Additive manufacturing of patterned 2D semiconductor through recyclable masked growth", "venue": "Proceedings of the National Academy of Sciences", "year": 2019 }, { "abstract": "Chemical vapor deposition (CVD) is a powerful method employed for high quality monolayer crystal growth of 2D transition metal dichalcogenides with much effort invested toward improving the growth process. Here, we report a novel method for CVD based growth of monolayer molybdenum disulfide (MoS2) by using thermally evaporated thin films of molybdenum trioxide (MoO3) as the molybdenum (Mo) source for coevaporation. Uniform evaporation rate of MoO3 thin films provides uniform Mo vapors which promote highly reproducible single crystal growth of MoS2 throughout the substrate. These high quality crystals are as large as 95 mm and are characterized by scanning electron microscopy, Raman spectroscopy, photoluminescence spectroscopy, atomic force microscopy, and transmission electron microscopy. The bottom gated field effect transistors fabricated using the as grown single crystals show n type transistor behavior with a good on/off ratio of 106 under ambient conditions. Our results presented here address the precursor vapor control during the CVD process and is a major step forward toward reproducible growth of MoS2 for future semiconductor device applications.", "author_names": [ "Sajeevi Sankalpani Withanage", "Hirokjyoti Kalita", "Hee-Suk Chung", "Tania Roy", "Yeonwoong Jung", "Saiful I Khondaker" ], "corpus_id": 53691325, "doc_id": "53691325", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Uniform Vapor Pressure Based Chemical Vapor Deposition Growth of MoS2 Using MoO3 Thin Film as a Precursor for Coevaporation", "venue": "ACS omega", "year": 2018 }, { "abstract": "We present a DC AC Hall effect analysis on transition metal dichalcogenides comprising natural crystals of molybdenum disulfide and tungsten diselenide; and synthetic crystals of hafnium diselenide, molybdenum ditelluride, molybdenum diselenide and niobium doped molybdenum disulfide. We observe a wide range of Hall mobility and carrier concentration values with either a net electron or hole carrier type. The synthetic niobium doped molybdenum disulfide crystal exhibits a net hole carrier type and a carrier concentration approximately two orders of magnitude higher than a non intentionally doped natural molybdenum disulfide crystal, with an equivalent reduction in Hall mobility. This synthetic niobium doped molybdenum disulfide crystal also shows a significantly reduced resistivity when compared to the other crystals. Secondary ion mass spectrometry shows higher counts of niobium in the intentionally doped synthetic niobium molybdenum disulfide crystal, in addition to various other high contamination counts in both the natural and synthetic molybdenum disulfide crystals, correlating well with the significant range of high resistivity observed. Compared to silicon, the resistivity in these contaminated TMD materials reduces less rapidly with increasing equivalent carrier concentration levels, and the resistivity is higher in magnitude by a factor of approximately 4 10 when compared to silicon, which in turn reduces the achievable Hall mobility by at least a similar factor. It is therefore suggested that more controlled growth methods of TMD materials which lead to significantly reduced contamination elements and levels, with improved stoichiometry, could potentially provide a significant increase in Hall mobility assuming no change in carrier properties.", "author_names": [ "Scott Monaghan", "Farzan Gity", "Ray Duffy", "Gioele Mirabelli", "Melissa M McCarthy", "Karim Cherkaoui", "Ian M Povey", "Roger Nagle", "Paul K Hurley", "Jeffrey R Lindemuth", "Enrico Napolitani" ], "corpus_id": 22169993, "doc_id": "22169993", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Hall effect mobility for a selection of natural and synthetic 2D semiconductor crystals", "venue": "2017 Joint International EUROSOI Workshop and International Conference on Ultimate Integration on Silicon (EUROSOI ULIS)", "year": 2017 } ]

[ { "abstract": "Use of electricity in industry opened a new age which is dominated by industrial automation. In the beginning, automation systems were based on electro mechanical systems consisting of relays and contactors. Developments in semiconductor technology inevitably transformed the existing structure and cause electronic controlled Programmable Logic Controller (PLC) to prevail in the automation systems. PLCs consist of a microcontroller/microprocessor, relay or transistor for switching, isolating equipment such as opto couplers and voltage converter/inverters. Industrial PLCs are quite expensive devices. In this study, design and implementation of a low cost PLC using PIC18F4580 microcontroller are realized. Special software including a graphical user interface is developed for programming the PLC and transferring code data to the device. Both ladder diagram and word instructions can be used for programming the PLC.", "author_names": [ "Ufuk Sanver", "Erdem Yavuz", "Can Eyupoglu", "Tuncay Uzun" ], "corpus_id": 3930871, "doc_id": "3930871", "n_citations": 5, "n_key_citations": 1, "score": 0, "title": "Design and implementation of a programmable logic controller using PIC18F4580", "venue": "2018 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus)", "year": 2018 }, { "abstract": "This paper describes the design of a nonlinear linearizing controller based on feedback linearizing method to stabilize a nonlinear magnetic levitation system. The linearized model states are selected through input state linearization, and the mathematical expression of the linearizing controller is obtained. An additional innovative integral LQR is designed to make the closed loop system more robust. The closed loop system is implemented in real time on an IEC 61499 standardbased programmable logic controller using a new model transformation technique. The closed loop system is simulated in MATLAB/SIMULINK and TwinCAT 3 real time environment, and the simulation results obtained on both environments are compared.", "author_names": [], "corpus_id": 215734963, "doc_id": "215734963", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Development of a Nonlinear Linearizing Controller Using Input Output Input State Linearization for Implementation in Programmable Logic Controller (PLC)", "venue": "", "year": 2019 }, { "abstract": "V magistrskem delu je prikazano snovanje in uporaba mehkega (Fuzzy) regulacijskega sistema na primeru regulacije pretoka zraka skozi sistem dveh tlacnih posod in regulacije temperature grelca. Izvedba algoritma mehkega sklepanja je bila zasnovana na osnovi Siemens Fuzzy Control orodja, ki pa ga v novejsih krmilnikih ni bilo mogoce uporabiti. Razvit in implementiran je bil algoritem mehkega sklepanja v Siemens TIA portalu. V obeh primerih je bila izvedena primerjava mehkega regulatorja z linearnim PID regulatorjem. Za prikaz in analizo delovanja regulacijskega sistema je bil izdelan uporabniski vmesnik SCADA s programom Siemens WinCC.", "author_names": [ "Andrej Jozic" ], "corpus_id": 201886030, "doc_id": "201886030", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design and implementation of a Fuzzy control algorithm on a programmable logic controller magistrsko delo", "venue": "", "year": 2019 }, { "abstract": "V magistrskem delu je prikazano snovanje in uporaba mehkega (Fuzzy) regulacijskega sistema na primeru regulacije pretoka zraka skozi sistem dveh tlacnih posod in regulacije temperature grelca. Izvedba algoritma mehkega sklepanja je bila zasnovana na osnovi Siemens Fuzzy Control orodja, ki pa ga v novejsih krmilnikih ni bilo mogoce uporabiti. Razvit in implementiran je bil algoritem mehkega sklepanja v Siemens TIA portalu. V obeh primerih je bila izvedena primerjava mehkega regulatorja z linearnim PID regulatorjem. Za prikaz in analizo delovanja regulacijskega sistema je bil izdelan uporabniski vmesnik SCADA s programom Siemens WinCC.", "author_names": [ "Andrej Jozic" ], "corpus_id": 149897602, "doc_id": "149897602", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design and implementation of a Fuzzy control algorithm on a programmable logic controller", "venue": "", "year": 2019 }, { "abstract": "Biodiesel washing is part of a biodiesel production process that aims to remove impurities contained in biodiesel. In this research, the process of biodiesel washing was conducted at a liquid separation mini plant using mechanical stirring method. A capacitive sensor was utilized to detect interface which is used in the separation between the two liquids, biodiesel and water. This sensor acts as a substitute for the operator who does visual observation in liquid separation. The temperature and the level of water and mixture in the mixing tank to make the process run optimally was also constantly controlled. The process of washing or purification was carried out with 3 times iteration. Programmable logic controller (PLC) was used as a controller device that serves to detect the sensor readings and operate the pumps and valves in this biodiesel washing process. The water mixing process was tested by mixing water temperature ranging from 70degC to 75degC with 25degC water for 2 times to get the water temperature of 55degC. The capacitive sensor module was able to differentiate water from biodiesel. The module produced 58.2 84.5 kHz voltage signal when detecting water and 84.5 98.8 kHz voltage signal when detecting biodiesel in static condition. The time delay for the transfer from water discharge valve to biodiesel discharge valve is 12 seconds. The overall, biodiesel washing automation system can be operated in 18 minutes duration for one washing cycle (excluding the duration of the water heating)", "author_names": [ "Gitta Septiani", "Rivon Tridesman", "Estiyanti Ekawati" ], "corpus_id": 12619059, "doc_id": "12619059", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Design and implementation of biodiesel washing automation system with set of sensors and programmable logic controller device", "venue": "2015 International Conference on Sustainable Energy Engineering and Application (ICSEEA)", "year": 2015 }, { "abstract": "In order to ensure the security of each set of tracks, signalization systems are build track specific, even though they have similar building blocks. In this Project it is aimed to design a modular, adaptable signalization system, while sticking to the asked conditions and safety measures and implement it on a programmable logic controller (PLC) First order of business was to design the general architecture of the whole system while complying with the interlocking systems safety regulations. Afterwards the main blocks that were used to build the larger system (rail block, intersection block, route block and signal block) were designed using the automata approach. The PLC's that were planned on being used in the future belonged to Siemens S7 family. Accordingly Siemens' SIMATIC STEP 7 software was chosen to define the inputs, outputs, events, cases and functions and to finally simulate them all.", "author_names": [ "Burcu Akmansayar", "Salman Kurtulan", "Siddika Berna Ors Yalcin" ], "corpus_id": 9716887, "doc_id": "9716887", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Design of core blocks and implementation on a programmable logic controller for a train signalization system", "venue": "2015 23nd Signal Processing and Communications Applications Conference (SIU)", "year": 2015 }, { "abstract": "", "author_names": [ "Aleksey A Imaev" ], "corpus_id": 57138508, "doc_id": "57138508", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design and implementation of a programmable logic controller lab: An internet based monitoring and control of a process", "venue": "", "year": 2002 }, { "abstract": "The design and implementation of a classical control system laboratory based on PLC control system is introduced in this paper. To design and implement the system, two parts must be produced. The first is software for PLC and the second is hardware for experiments related to the programs. The PLC control system used in the design is LS industrial system company GM7 DR40A 24/16 Digital I/O and single Analog I/O module, two photoelectric sensors from Atonic company' the first with the model BR100 DDT P, and the second BEN10M TFR. An approximate sensor with 5 sides is detected, four of CMOS BCD 7 Segment driven by CD4511B, two relays: 2 poles and 3 poles, six voltages and an ammeter measurement, DC motor and 24 VDC power supply and many connecters and pinions. Satisfactory results are obtained by executing twenty four experiments for classical control theory that fulfill the requirements of control theory in undergraduate stage and replace the old experiments executed by PID controller where the practice system is implemented by PLC control now.", "author_names": [ "Yousif Al Mashhadany" ], "corpus_id": 52221424, "doc_id": "52221424", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Design and Implement of a Programmable Logic Controller (PLC) for Classical Control Laboratory", "venue": "", "year": 2012 }, { "abstract": "Direct Current (DC) motor position control using Programmable Logic Controller (PLC) is one of the applications which are widely used in automation industries. The aim of this project is to implement a Proportional Integral Derivative (PID) controller in a DC motor control system of The Conveyor System. The project is consists of two stages, classical controller and PID controller. The classical controller and PID controller were implemented in PLC and the results of both methods were compared. The system response of both controllers were compared and analyzed. Throughout the analysis, the PID control system illustrated better performance as compared to the classical control system controller in DC motor position control.", "author_names": [ "Muhammad Sharfi Najib", "Mohd Shawal Jadin", "Raja Mohd Taufika Raja Ismail", "Mohd Rusllim Mohamed" ], "corpus_id": 109053212, "doc_id": "109053212", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Design and implementation of PID controller in programmable logic controller for DC motor position control of the conveyor system", "venue": "", "year": 2007 }, { "abstract": "This programmable logic controller can provide logical and timer functions to control in different environments, especially for the intelligent resident. It is consisted of 3 modules: I/O module, processor and programmer. Microcontroller unit MC68HC05C9 processes signal according to the user program saved in EEPROM. User can program with the input and output signal flexibly.", "author_names": [ "Li Zhe" ], "corpus_id": 63072274, "doc_id": "63072274", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A Design and Implementation of Programmable Logic Controller by Microcontroller 68HC05C9", "venue": "", "year": 2002 } ]

[ { "abstract": "The time resolved measurement of capacitance is a powerful method in the evaluation of defects in semiconductors, carrier dynamics in quantum dots, and photo induced dynamics in photovoltaic materials. In this study, we demonstrate time resolved capacitance measurements at the nanoscale using scanning nonlinear dielectric microscopy. We detected the capacitance transient of SiO2/4H SiC interfaces triggered by the application of a 3 ns pulse, showing the high temporal resolution of the developed method. We exemplified the method with the evaluation of the density and activation energy of defects at SiO2/4H SiC interfaces that verified the quantitative capability and high sensitivity of the method. Two dimensional mapping of the interface states showed nanoscale inhomogeneous contrasts, implying that the physical origin of the defects at SiO2/4H SiC interfaces is microscopically clustered.", "author_names": [ "Yuji Yamagishi", "Yasuo Cho" ], "corpus_id": 125342157, "doc_id": "125342157", "n_citations": 13, "n_key_citations": 3, "score": 1, "title": "Nanosecond microscopy of capacitance at SiO2/4H SiC interfaces by time resolved scanning nonlinear dielectric microscopy", "venue": "", "year": 2017 }, { "abstract": "Noncontact scanning nonlinear dielectric microscopy (NC SNDM) is a microwave based scanning probe microscopy method detecting the variation in the tip sample capacitance. By detecting the second order nonlinear effect in dielectric polarization, this method enables imaging spontaneous polarization in materials. Although dielectric polarization is a material property formulated in a somewhat macroscopic sense, a series of the measurement results on cleaned semiconductor surfaces suggest that atomic scale polarization, or atomic dipoles, can be resolved by NC SNDM. Here we review unique capability of this method and mention its significance in solid state and surface physics. We also explain a novel extension of NC SNDM, called noncontact scanning nonlinear dielectric potentiometry (NC SNDP) and its application to the nanoscale evaluation of two dimensional materials. The results reviewed here show that these methods will be tools for the atomic scale investigation of surface and interface charge states even in a quantitative way.", "author_names": [ "K Yamasue", "Yasuo Cho" ], "corpus_id": 225080095, "doc_id": "225080095", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Atomic Resolution Studies on Surface Dipoles by Noncontact Scanning Nonlinear Dielectric Microscopy and Potentiometry", "venue": "2020 Joint Conference of the IEEE International Frequency Control Symposium and International Symposium on Applications of Ferroelectrics (IFCS ISAF)", "year": 2020 }, { "abstract": "Scanning nonlinear dielectric microscopy (SNDM) can be used to visualize the carrier distribution in semiconductors with high sensitivity and spatial resolution. We recently proposed a complementary method named C/z SNDM that avoids the problem of contrast reversal. This paper describes a methodology for calculating the signal intensity in C/z SNDM using examples. For the simulation, the capacitance of a conductive probe metal/oxide/semiconductor model was calculated and then the response signal for various probe sample distances was analyzed. The simulation results confirm that the C/z SNDM signal intensity increases monotonically with dopant concentration, avoiding contrast reversal. Moreover, in addition to the fundamental (1o) signal, higher harmonic (2o, 3o) signals have sufficient intensities to be detected. The results suggest that the detection sensitivity for low dopant concentrations can be improved by conducting the measurement under an appropriate dc bias.", "author_names": [ "Yoshiomi Hiranaga", "Yasuo Cho" ], "corpus_id": 201714600, "doc_id": "201714600", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Carrier distribution imaging using C/z mode scanning nonlinear dielectric microscopy.", "venue": "The Review of scientific instruments", "year": 2019 }, { "abstract": "We discuss the feasibility of interface defect density estimation using scanning nonlinear dielectric microscopy (SNDM) With reference to the previous results on SiO2/SiC gate stacks, we evaluate the non uniformity in the microscopy images of SiO2/Si and high k/SiO2/Si gate stacks. The results suggest that a high k layer on a SiO2/Si gate stack has little impact on the quality of interface. Our procedure possibly gives a useful method for the nanoscale evaluation of interface quality at gate stacks with Si substrates. We also measure local capacitance voltage (CV) spectrum by newly developed time resolved SNDM, which show CV spectrum gradually changed during the measurement.", "author_names": [ "Koharu Suzuki", "K Yamasue", "Yasuo Cho" ], "corpus_id": 211119167, "doc_id": "211119167", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A Study on Evaluation of Interface Defect Density on High K/SiO2/Si and SiO2/Si Gate Stacks using Scanning Nonlinear Dielectric Microscopy", "venue": "2019 IEEE International Integrated Reliability Workshop (IIRW)", "year": 2019 }, { "abstract": "Abstract The effect of Nb5+ on the crystallographic structure, electrical properties and the dielectric behaviour of Na 0.5 La 0.5 Cu 3 Ti 4 x Nb x O 12 ceramics prepared via the solid state reaction method were investigated. Rietveld refinement of the powder diffraction data confirmed a cubic, single phase structure with space group Im3. A low frequency Debye type relaxation is observed for the Nb doped samples in addition to the usually observed high frequency relaxation. The grain boundary resistance decreased significantly with increasing Nb5+ dopant. The reduced grain boundary resistivity was found to be responsible for the decrease in the potential barrier at the grain boundary as observed from the overall variation of current density electric field (J E) characteristics. The dielectric constant at low Frequency is increased with increasing Nb content. The dielectric behaviour of the compound is explained on the basis of the Internal Barrier Layer Capacitance (IBLC) model.", "author_names": [ "and K George Thomas", "Merin K George", "D Sajan", "Kevin Abraham", "Jini Thomas", "K V Saban" ], "corpus_id": 104325639, "doc_id": "104325639", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Effect of niobium doping on the dielectric and nonlinear current voltage characteristics of Na0.5La0.5Cu3Ti4O12 ceramics", "venue": "Optical Materials", "year": 2019 }, { "abstract": "[Shi Yan toJie Guo nXing SiCJi Ban noSiMian ni20 nmnoRe Suan Hua Mo gaXing Cheng saretaShi Liao woPing Jia Dui Xiang toshiteYong ita. NOFen Wei Qi Xia dePOAChu Li saretaShi Liao toPOAChu Li nosareteinaiShi Liao noEr Zhong Lei noShi Liao niDui shiteSNDMCe Ding woXing tsuta. ma zuBian Diao Xin Hao noZhou Bo Shu wo1 MHz, Shi Liao niYin Jia surubaiasuDian Ya ha0 Vtoshite|dC/dV|Xiang woQu De shita. konoShi Qu De sa reta|dC/dV|Xiang woTu 1(a)toTu 1(b)nisorezoreShi su. Zou Cha Ling Yu noMian Nei deha|dC/dV|gaKong Jian De niBu Jun Yi niFen Bu shiteori, Te ni POA Chu Li sareteinaiShi Liao dehaMian Nei denoRong Liang Te Xing nobaratsukigaDa kiikotogaFen karu. Ci niTu 1(a)Nei noChi Xian toTu 1(b)Nei noQing Xian deShi shitaXian Shang deCe Ding sareta, |dC/dV|toBan Dao Ti Ceng henoYin Jia baiasunoGuan Xi woTu 1(c)niShi su. |dC/dV|nopikugaQue Ren dekiruga, konouchi POA Chu Li sareteinaiShi Liao dehapikunoZui Da Zhi |dC/dV|max)gaXiang Dui De niXiao saku, matapikunoBan Zhi Quan Fu (FWHM)haDa kii. korehaPOAChu Li sareteinaiShi Liao noJie Mian Zhun Wei Mi Du gaXiang Dui De niGao ku, Jin Shu Tan Zhen /Suan Hua Mo /Ban Dao Ti deGou Cheng sareruMOSGou Zao noC VTe Xing ga\"stretch out\"shiteirukotoni Dui Ying surutoKao erareru. saraniTu 1(b)noXian Fen ABShang niokeru|dC/dV|maxtoFWHMnoFen Bu woTu 1(d)niShi su. Xiang Dui De ni|dC/dV|maxgaDa kikuFWHMgaXiao saiLing Yu (i)to, sonoNi noQing Xiang woShi suLing Yu (ii)gaCun Zai shiteirukotogaQue Ren deki ruga, koreranoLing Yu hasorezoreJie Mian Zhun Wei Mi Du gaDi iLing Yu toGao iLing Yu niDui Ying shiteirutoKao erare, Jie Mian Zhun Wei Mi Du gaMian Nei deBu Jun Yi niFen Bu shiteirukotogaShi Suo sareru. [Xie Ci Ben Yan Jiu haSIP (Zhan Lue De inobeshiyonChuang Zao puroguramu)/Ci Shi Dai pawaerekutorokusuniyotsuteShi Shi sareta. [Can Kao Wen Xian [1] Y. Cho, A. Kirihara, T. Saeki, Rev. Sci. Instrum. 67 (1996) 2297", "author_names": [ "Yuji Yamagishi", "N Chinone", "Yasuo Cho" ], "corpus_id": 136068270, "doc_id": "136068270", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Evaluation of Local Capacitance Characteristics of SiO 2 /4H SiC Interface by Scanning Nonlinear Dielectric Microscopy", "venue": "", "year": 2016 }, { "abstract": "Outer hair cell (OHC) nonlinear capacitance (NLC) represents voltage sensor charge movements of prestin (SLC26a5) the protein responsible for OHC electromotility. Previous measures of NLC frequency response have employed methods which did not assess the influence of dielectric loss (sensor charge movements out of phase with voltage) that may occur, and such loss conceivably may influence prestin's frequency dependent activity. Here we evaluate prestin's complex capacitance out to 30 kHz and find that prestin's frequency response determined using this approach coincides with all previous estimates. We also show that membrane tension has no effect on prestin's frequency response, despite substantial shifts in its voltage operating range, indicating that prestin transition rate alterations do not account for the shifts. The magnitude roll off of prestin activity across frequency surpasses the reductions of NLC caused by salicylate treatments that are known to abolish cochlear amplification. Such roll off likely limits the effectiveness of prestin in contributing to cochlear amplification at the very high acoustic frequencies processed by some mammals.", "author_names": [ "Joseph Santos-Sacchi", "Winston J T Tan" ], "corpus_id": 210932482, "doc_id": "210932482", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Complex nonlinear capacitance in outer hair cell macro patches: effects of membrane tension", "venue": "Scientific Reports", "year": 2020 }, { "abstract": "In this paper, the cracking fault occurred in the dynamic environment of the multi layer porcelain dielectric capacity used in a aerospace electronic product. The stress and deformation response in the PCB area where the multi layer porcelain dielectric capacity is located are reduced by a reasonable PCB layout. Damping materials are added to PCB to reduce vibration. The nonlinear damping characteristics of material damping and energy filtering are used to realize energy consumption in the area of multi layer porcelain dielectric capacity on PCB.", "author_names": [ "Zhang Yu", "Liu Mi" ], "corpus_id": 232071745, "doc_id": "232071745", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Research on reliability Optimization design of multilayer porcelain dielectric capacitance of aerospace electronic products based on dynamic simulation", "venue": "2020 7th International Forum on Electrical Engineering and Automation (IFEEA)", "year": 2020 }, { "abstract": "We demonstrate that scanning nonlinear dielectric microscopy (SNDM) can be used for the nanoscale characterization of dominant carrier distribution on atomically thin MoS2 mechanically exfoliated on SiO2. For stable imaging without damaging microscopy tips and samples, SNDM was combined with peak force tapping mode atomic force microscopy. The identification of dominant carriers and their spatial distribution becomes possible even for single and few layer MoS2 on SiO2 using the proposed method allowing differential capacitance (dC/dV) imaging. We can expect that SNDM can also be applied to the evaluation of other two dimensional semiconductors and devices.We demonstrate that scanning nonlinear dielectric microscopy (SNDM) can be used for the nanoscale characterization of dominant carrier distribution on atomically thin MoS2 mechanically exfoliated on SiO2. For stable imaging without damaging microscopy tips and samples, SNDM was combined with peak force tapping mode atomic force microscopy. The identification of dominant carriers and their spatial distribution becomes possible even for single and few layer MoS2 on SiO2 using the proposed method allowing differential capacitance (dC/dV) imaging. We can expect that SNDM can also be applied to the evaluation of other two dimensional semiconductors and devices.", "author_names": [ "K Yamasue", "Yasuo Cho" ], "corpus_id": 125954040, "doc_id": "125954040", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "Local carrier distribution imaging on few layer MoS2 exfoliated on SiO2 by scanning nonlinear dielectric microscopy", "venue": "", "year": 2018 }, { "abstract": "A nanoscale linear permittivity imaging method based on scanning nonlinear dielectric microscopy (SNDM) was developed. The C/z mode SNDM (C/z SNDM) technique described herein employs probe height modulation to suppress disturbances originating from stray capacitance and to improve measurement stability. This method allows local permittivity distributions to be examined with extremely low noise levels (approximately 0.01 aF) by virtue of the highly sensitive probe. A cross section of a multilayer oxide film was visualized using C/z SNDM as a demonstration, and numerical simulations of the response signals were conducted to gain additional insights. The experimental signal intensities were found to be in a good agreement with the theoretical values, with the exception of the background components, demonstrating that absolute sample permittivity values could be determined. The signal profiles near the boundaries between different dielectrics were calculated using various vibration amplitudes and the boundary transition widths were obtained. The beneficial aspects of higher harmonic response imaging are discussed herein, taking into account assessments of spatial resolution and quantitation.", "author_names": [ "Yoshiomi Hiranaga", "N Chinone", "Yasuo Cho" ], "corpus_id": 4345971, "doc_id": "4345971", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Nanoscale linear permittivity imaging based on scanning nonlinear dielectric microscopy.", "venue": "Nanotechnology", "year": 2018 } ]

[ { "abstract": "Quantum dots (QD) which is considered the ideal candidate of third generation semiconductor lighting, has the advantages of high quantum yield, adjustable emission wavelength and narrow full width at half maxima (FWHM) thus it is an ideal choice as the colour converting materials for LEDs. InGaN LEDs are the main choice of solid state lighting, which is always applied with Ce doped yttrium aluminum garnet (YAG: Ce3+ yellow phosphor to achieve white light. However, white light achieved by this method has a low colour rendering index (CRI) mainly because of the missing of red spectral components in YAG: Ce3+ thus the CRI is lower than 80 and the correlated colour temperature (CCT) is always above 6500K. In order to increase the CRI of white LEDs, in this paper, we fabricated yellow CQDs and applied it on blue LED chips, red QD films were also used to increase the CRI of our white LEDs. The result shows that the white LEDs with yellow CQDs and red QD films has a max CRI of 94.3 at a driving current of 70mA, the Commission International de L'Eclairage (CIE) chromaticity coordinates are (0.325, 0.3435) and the CCT is 5832K, which is white light with high CRI and can be used in indoor lighting.", "author_names": [ "Yuxian Yan", "Doudou Zhang", "Luqiao Yin", "Jianhua Zhang" ], "corpus_id": 230999135, "doc_id": "230999135", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "CQD LEDs with High Colour Rendering Index", "venue": "2020 17th China International Forum on Solid State Lighting 2020 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)", "year": 2020 }, { "abstract": "Existing white LEDs use a blue LED chip to stimulate phosphor powder to form white light. The surface coated with a phosphor layer directly affects the colour rendering index, the luminous efficacy and the colour temperature. We have encapsulated a white LED source with chip on board packaging to meet the requirements for a high power, high colour temperature, high colour rendering index LED using stacked phosphor coating. This chip on board white LED light source can achieve a colour rendering index over 95 and a luminous efficacy over 100 lm/W while the colour temperature is 5700 K. This technology can be widely used in commercial lighting applications where high quality light sources are needed.", "author_names": [ "Peng Ge", "Z Zhou", "Jun Zhang", "Haiyan Wang" ], "corpus_id": 117599398, "doc_id": "117599398", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Stacked phosphor coating technology for white LEDs with high colour temperature and high colour rendering index", "venue": "", "year": 2019 }, { "abstract": "Designing two step tuning based on substitution of multiple cation lattices and energy transfer successfully achieved versatile colour output for single phase phosphor converted white LEDs in this work. Herein, we chose whitlockite type Ca9LiY0.667(PO4)7 compound as a host which provides multiple cation sites for Eu2+ occupation. Spectral results indicate that the Ca9LiY0.667(PO4)7:Eu2+ phosphor emits a cold white emission due to its multiple emission bands at about 420, 480, and 530 nm, which correspond to emissions from the M(3) M(1)/M(2) and M(5) cation sites as ascertained by the Rietveld refinement method. In order to enhance the red emission of CLYPO:Eu2+ phosphors, they were codoped with Mn2+ Warm white emission in a single phase host based on energy transfer was successfully obtained in the CLYPO:Eu2+,Mn2+ phosphors. The excitation band of the CLYPO:Eu2+,Mn2+ phosphors in the 360 to 450 nm range perfectly coincides with that of commercial LED chips, implying that these phosphors are desirable for white LED applications. White LEDs with a higher color rendering index (Ra 90.2) and a lower correlated color temperature (CCT 3614 K) were achieved by using a single phase CLYPO:0.03Eu2+,0.10Mn2+ phosphor and a 395 nm InGaN LED chip.", "author_names": [ "Mingshan Cui", "Jindi Wang", "Mengmeng Shang", "Jin-Hua Li", "Qi Wei", "Peipei Dang", "Ho Seong Jang", "Jun Lin" ], "corpus_id": 140014947, "doc_id": "140014947", "n_citations": 57, "n_key_citations": 0, "score": 0, "title": "Full visible light emission in Eu2+,Mn2+ doped Ca9LiY0.667(PO4)7 phosphors based on multiple crystal lattice substitution and energy transfer for warm white LEDs with high colour rendering", "venue": "", "year": 2019 }, { "abstract": "CdS/Si multi interface nanoheterojunctions (CdS/Si NPA) were fabricated by depositing CdS nanocrystallites (nc CdS) on silicon nanoporous pillar arrays (Si NPA) by chemical bath deposition. White electroluminescence (EL) with a high colour rendering index from a prototypical light emitting diode based on CdS/Si NPA has been reported, which does not need complex colour mixing or conversion techniques. The white EL can be composed into three primary colours, which include blue emissions from the Si NPA, the green emissions from the bandgap emission of nc CdS and red emissions from the defects in the nc CdS. Through the annealing treatment, the chromaticity coordinate and correlated colour temperature can be tuned. This indicates that CdS/Si NPA is a potential candidate in the one chip white LEDs.", "author_names": [ "Yiming Li", "Yue Li Song", "Peng Fei Ji", "Feng Qun Zhou" ], "corpus_id": 7166671, "doc_id": "7166671", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "White light emission with tuneable colour temperature and high colour rendering index from CdS/Si multi interface nanoheterojunctions.", "venue": "Nanoscale", "year": 2017 }, { "abstract": "Existing white light LED technology uses a blue light LED chip to stimulate a phosphor powder to form white light. The phosphor layer on the surface directly affects the colour rendering index, luminous efficacy and colour temperature of the LED. We propose a high power, white LED, chip on board package technology to achieve high colour rendering index and high luminous efficacy by optimising the spectral power distribution. The chip on board package light source can achieve a colour rendering index over 90 and a luminous efficacy over 90 lm/W while the power is 45W. It can be widely used in commercial lighting applications.", "author_names": [ "Z Zhou", "H Wang", "Jingwen Zhang", "Jie Su", "Peng Ge" ], "corpus_id": 113625419, "doc_id": "113625419", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "LED chip on board package with high colour rendering index and high luminous efficacy", "venue": "", "year": 2018 }, { "abstract": "Abstract The circadian rhythm is influenced by light and other non visual responses in humans. Recent researches have shown that the visual quantity illuminance is not appropriate for evaluating non visual effects. Metrics such as the circadian stimulus have been developed to address this issue. One of the limitations with circadian metrics is that the determination requires a spectroradiometer instead of the standard illuminance meters. In this article, a simple circadian stimulus calculation model for white light sources is presented. The model is determined with the parameters illuminance, correlated colour temperature CCT and colour rendering index Ra. The accuracy and reliability of the model is high and is based on 7641 spectra with 19 illuminance levels, which are generated using a heuristic optimisation procedure. In addition, the model has been internally validated with the method repeated split data and has an error deviation of 0.058 for CCT 3710 K and 0.045 for CCT 3710 K at 99% confidence interval in the circadian stimulus CS range between 0.2 and 0.5. Since the quantities illuminance, correlated temperature and colour rendering index are common in practice, this model enables non visual planning of illumination installations by lighting designers or lighting design tools. Furthermore, it allows retrospective analysis of past non visual research results in scientific studies, where illuminance and correlated colour temperature were provided.", "author_names": [ "William Truong", "Babak Zandi", "Vinh Quang Trinh", "Tran Quoc Khanh" ], "corpus_id": 225378584, "doc_id": "225378584", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Circadian metric Computation of circadian stimulus using illuminance, correlated colour temperature and colour rendering index", "venue": "Building and Environment", "year": 2020 }, { "abstract": "This paper describes how CIE colour fidelity index Rf values are correlated with CIE Ra colour rendering index values for typical FL fluorescent lamps. The results shows that for broad band FL lamps Rf doesn't introduce drastically changes in relation to Ra values. The other situation is with narrow band FL lamps whose spectral power distribution was designed for achieving of high Ra value. At that case there is no correlation between Ra and Rf. Streszczenie. W artykule przedstawiono badania nad zaleznoscia wskaznika wiernosci barwy CIE Rf od wskaznika oddawania barw CIE Ra dla standardowych lamp fluorescencyjnych (swietlowek) FL. Wyniki pokazuja, ze dla szerokopasmowych swietlowek, wskaznik Rf nie wprowadza drastycznych zmian w stosunku do wartosci Ra. W przypadku waskopasmowych lamp FL, tj. takich ktorych rozklad widmowy zostal zaprojektowany w celu osiagniecia wysokiej wartosci Ra pomimo faktu iz wizualnie ich swiatlo nie oddaje perfekcyjnie barw, wartosc wskaznika Rf nie koreluje z Ra. (Jakosc oddawania barw wspolczesnych lamp fluorescencyjnych okreslona zdefiniowanym przez CIE wskaznikiem wiernosci barwy oraz wskaznikiem oddawania barw)", "author_names": [ "J Kowalska" ], "corpus_id": 195851417, "doc_id": "195851417", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Colour rendition quality of typical fluorescent lamps determined by CIE Colour Fidelity Index and Colour Rendering Index", "venue": "PRZEGLAD ELEKTROTECHNICZNY", "year": 2019 }, { "abstract": "Lu modified (Ca2.94 xLuxCe0.06)(Sc2 yMgy)Si3O12 (CLSMS Ce3+ yellow emitting phosphors are prepared by a solid state reaction. Controllable luminescent intensity and emitting colour are studied as a function of Lu and Mg contents. Fixing the Mg content to be 1, the effect of Lu content on crystal phase formation, luminescence properties and temperature characteristics is studied. It is revealed that the Lu induced luminescent enhancement is the result of an increase in absorbance of Ce3+ rather than the internal quantum efficiency. Intense and broadband emission is realized by controlling the Lu content to obtain a pure CLSMS crystal phase. The maximum luminescence intensity is obtained at x 0.54, which is as high as 156% of the Lu free phosphor. The Lu containing phosphor also exhibits better temperature characteristics for its big activation energy (0.20 eV) than the Lu free one (0.18 eV) Combining the present phosphor with a blue light emitting diode (LED) chip, a white LED with an excellent colour rendering index Ra of 86 and a high luminous efficiency of 86 lm W 1 is obtained. The results of the present study demonstrate that the CLSMS Ce3+ phosphors show a good performance and are attractive candidates for commercial applications when used in white LEDs.", "author_names": [ "Yongfu Liu", "Xia Zhang", "Zhendong Hao", "Wei Lu", "Xingyuan Liu", "Xiaojun Wang", "Jiahua Zhang" ], "corpus_id": 55699704, "doc_id": "55699704", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Crystal structure and luminescence properties of (Ca2.94 xLuxCe0.06)(Sc2 yMgy)Si3O12 phosphors for white LEDs with excellent colour rendering and high luminous efficiency", "venue": "", "year": 2011 }, { "abstract": "Ca8.78Ce (PO4)7:0.06Eu2+,0.16Mn2+,xH3BO3 phosphors were synthesized by a high temperature solid state reaction method. XRD patterns of the samples indicate that H3BO3 doping does not change the phase formation. However, H3BO3 doping can change the emission intensities of Ce3+ Eu2+ Mn2+ and the energy transfer efficiencies of Ce3+ Eu2+ and Ce3+ Mn2+ The reason for this is that H3BO3 doping changes the luminescent centre and the distance between different luminescent centres to some degree. When the ligand polyhedron volume decreases, the lifetime and emission intensity of the luminescent centre will increase. When the distance between Ce3+ and Eu2+/Mn2+ decreases, the energy transfer efficiency between them will increase. In Ca8.78Ce(PO4)7:0.06Eu2+,0.16Mn2+,xH3BO3, the average volume of an (Eu/Mn)1/2/3 O8/9] polyhedron will decrease from 27.511 A3 to 21.847 A3, and the average distance between Ce and (Eu/Mn)1/2 will decrease from 3.702 A to 3.573 A with increased doping amounts of H3BO3 from 0 to 7. Meanwhile, the emission intensity and lifetime of Ce3+ decrease, and those of Eu2+/Mn2+ increase. Furthermore, the energy transfer efficiency from Ce3+ to Eu2+/Mn2+ and the quantum efficiency are improved. H3BO3 doping improves the ratio of red, green and blue colours of the spectrum, which improves the colour rendering index of materials from 80.5 to 90.7. H3BO3 doping also improves the thermal stability of the material to some degree. The quenching temperature of Eu2+ is improved from 75 degC to 100 degC.", "author_names": [ "Chao Wang", "Zhijun Wang", "Jinge Cheng", "Zhenling Li", "Miaomiao Tian", "Zhi-ping Yang", "Panlai Li" ], "corpus_id": 104744844, "doc_id": "104744844", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Improvement of emission intensity, colour rendering index and thermal stability of Ca9Ce(PO4)7:Eu2+,Mn2+via H3BO3 doping", "venue": "", "year": 2018 }, { "abstract": "Four heteroleptic platinum complexes (FPtXND) bearing 4 hydroxy 1,5 naphthyridine derivatives functionalized with dimethyl (X mm) phenoxy (X OPh) piperidine (X pp) or carbazole (X Cz) units as one ligand (XND) and 2 (2,4 difluorophenyl)pyridine as the other common ligand (F) were newly synthesized and characterized. The crystal structures of FPtOPhND and FPtCzND were determined by single crystal X ray diffraction crystallography. Although they have a short plane to plane packing distance of 3.62 and 3.39 A, respectively, both platinum complexes have different molecular packing patterns, which affect their photoluminescence (PL) in solution and electroluminescence (EL) in the solid state. Due to the contribution from both monomers and excimers/aggregates, all of the platinum complexes exhibited broad and red shifted PL in concentrated solutions as well as in doped thin films. In the monochromatic organic lighting diode (OLED) testing, FPtXND doped in 4,4' di(9H carbazol 9 yl) 1,1' biphenyl (CBP) exhibited greenish yellow or orange yellow EL, of which FPtOPhND has the highest EL efficiency mainly due to its high solution PL quantum yield of 21% Hybrid white OLEDs were first achieved with a single emitting layer configuration, of which highly fluorescent blue N,N' di 1 naphthalenyl N,N' diphenyl [1,1':4',1':4',1' quaterphenyl] 4,4' diamine (4P NPD) was used as the host material for all four platinum complexes. To improve the performance of the FPtOPhND based hybrid white OLEDs, double emitting layer configurations were adopted with CBP and 4P NPD as the host material. Virtually voltage independent, a white EL having CIEx,y (0.33, 0.31) and a CRI as high as 91 was obtained. The maximum EL efficiency of 11.8% 25.9 cd A 1, or 11.6 lm W 1 was acquired with FPtOPhND doped in the double emitting layer configuration of an OLED.", "author_names": [ "Anurach Poloek", "Chiao-Wen Lin", "Chin-Ti Chen", "Chao-Tsen Chen" ], "corpus_id": 94783519, "doc_id": "94783519", "n_citations": 25, "n_key_citations": 0, "score": 0, "title": "High colour rendering index and colour stable hybrid white efficient OLEDs with a double emitting layer structure using a single phosphorescence dopant of heteroleptic platinum complexes", "venue": "", "year": 2014 } ]

[ { "abstract": "Spin torque nano oscillators (STNOs) have outstanding advantages of a high degree of compactness, high frequency tunability, and good compatibility with the standard complementary metal oxide semiconductor process, which offer prospects for future wireless communication. There have as yet been no reports on wireless communication using STNOs, since the STNOs also have notable disadvantages such as lower output power and poorer spectral purity in comparison with those of LC voltage controlled oscillators. Here we show that wireless communication is achieved by a proper choice of modulation scheme despite these drawbacks of STNOs. By adopting direct binary amplitude shift keying modulation and non coherent demodulation, we demonstrate STNO based wireless communication with 200 kbps data rate at a distance of 1 m between transmitter and receiver. It is shown, from the analysis of STNO noise, that the maximum data rate can be extended up to 1.48 Gbps with 1 ns turn on time. For the fabricated STNO, the maximum data rate is 5 Mbps which is limited by the rise time measured in the total system. The result will provide a viable route to real microwave application of STNOs.", "author_names": [ "Hyun Seok Choi", "Sun-Yool Kang", "Seong Jun Cho", "Inn Yeal Oh", "Mincheol Shin", "Hyuncheol Park", "Chaun Jang", "Byoung-Chul Min", "Sang-il Kim", "Seungyung Park", "Chul Soon Park" ], "corpus_id": 14259928, "doc_id": "14259928", "n_citations": 90, "n_key_citations": 2, "score": 1, "title": "Spin nano oscillator based wireless communication", "venue": "Scientific reports", "year": 2014 }, { "abstract": "A low power spin torque nano oscillator (STNO) based wireless communication is demonstrated with a 180 nm CMOS transmitter and receiver. The ON OFF keying (OOK) modulation is employed to overcome the inherent drawbacks of the STNO, such as low output power and spectral purity, despite its advantages of a wide frequency tuning range and nano scale dimensions. As the magnetic tunnel junction (MJT) STNO with an MgO barrier has a maximum oscillation power as small as 75 dBm at 3.39 GHz, a 68 dB high gain amplification throughout the transmitter and receiver is needed for a 1 m wireless communication. A 36 dB high gain amplifier with a 3.9 dB low noise figure is implemented for the OOK transmitter together with an external modulator. The receiver is composed of a 3.5 dB low noise amplifier (LNA) with a high gain of 27 dB, gain boosted envelope detector, and baseband amplifier. The transmitter and receiver amplifiers are implemented with a highly isolated ground between each stage in order to prevent oscillations even at the high gain. The communication system with the STNO achieves an 11.8 Mb/s wireless data transmission over 1 m, with a power consumption of 41.4 mW. The implemented transmitter and receiver occupy 2.34 and 4.08 mm2, including all of the pads, respectively. The proposed system achieves the highest data rate with the lowest power consumption compared to those of the previous state of the art STNO based wireless communication systems.", "author_names": [ "Hee Sung Lee", "Seung Hun Kim", "Tae Hwan Jang", "Hee Gyum Park", "Byoung-Chul Min", "Seungyung Park", "Chul Soon Park" ], "corpus_id": 122379913, "doc_id": "122379913", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Power Efficient Spin Torque Nano Oscillator Based Wireless Communication With CMOS High Gain Low Noise Transmitter and Receiver", "venue": "IEEE Transactions on Magnetics", "year": 2019 }, { "abstract": "", "author_names": [ "Hyunseok Choi", "" ], "corpus_id": 232835618, "doc_id": "232835618", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Implementation of spin nano oscillator based wireless communication seupin nano baljingireul sayonghan museontongsin guhyeon", "venue": "", "year": 2015 }, { "abstract": "", "author_names": [ "" ], "corpus_id": 233507572, "doc_id": "233507572", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Spin nano oscillator based wireless communication", "venue": "", "year": 2014 }, { "abstract": "In this study, wireless transmitter and receiver including high gain amplifiers have been implemented in CMOS circuits for the first time for spin torque nano oscillator based wireless communication. The system block diagram is defined, and the power budget is calculated for 1 meter OOK wireless communication. The transmitter consists of STNO, LNA and SPDT switch, the receiver consists of LNA, demodulator and Schmitt trigger, and all are implemented in 0.18 um CMOS. Simulated gain of the LNA in transmitter and receiver are 38.5 dB and 31.0 dB, respectively. The fabricated chip sizes of transmitter and receiver are 2.34 and 4.42 mm2. The transmitter and receiver operate with 18 mW and 21.2 mW power dissipation, respectively. An STNO based wireless communication will be demonstrated using CMOS circuits in the presentation.", "author_names": [ "Hee Sung Lee", "Seung Hun Kim", "Tae Hwan Jang", "Chul Soon Park" ], "corpus_id": 4614172, "doc_id": "4614172", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "CMOS transmitter and receiver for spin torque nano oscillator based wireless communication", "venue": "2018 International Conference on Electronics, Information, and Communication (ICEIC)", "year": 2018 }, { "abstract": "Wireless transmission requires a circuitry to generate GHz range signal. Spin transfer torque devices are one of the promising candidates for generating stable signal in the GHz range through collective precession of the local spins in one of the ferromagnetic layer, known as free layer. Another ferromagnetic layer, fixed layer, acts as a medium to convert the incoming electric current into spin polarized current. This spin polarized current drives local spins of the free layer into constant precession. Factors like high linewidth, low output power and modulation rate are yet to be optimized to make these devices ready for use in practical wireless communication system. Recently, H. S. Choi et al. has demonstrated the first ever complete wireless communication system using spin torque nano oscillators (STNOs) through the amplitude shift keying (ASK) modulation. Here, we present a more detailed study of wireless communication as a function of the modulation frequency and distance between receiver and transmitting antennas (Tx) in order to determine modulation rate limits.", "author_names": [ "R Sharma", "Philipp Durrenfeld", "M Ranjbar", "Randy K Dumas", "Johan Akerman", "Pranaba Kishor Muduli" ], "corpus_id": 2293181, "doc_id": "2293181", "n_citations": 13, "n_key_citations": 1, "score": 0, "title": "Modulation rate study in spin torque oscillator based wireless communication system", "venue": "2015 IEEE Magnetics Conference (INTERMAG)", "year": 2015 }, { "abstract": "We study a wireless communication system based on a magnetic tunnel junction spin torque nano oscillator (STNO) by employing amplitude shift keying modulation. By varying the pulse modulation frequency (fm) from 1 kHz to 2 MHz and distance (D) between the antenna from 25 to 150 cm, we show a maximum data rate of 6 Mb/s (at D 25 cm and fm 1 MHz) a limit imposed by our setup and noise generated by the STNO itself. We also report the average amplitude noise (Sda) and average white frequency noise (Swh) of the wireless communication system and discuss their dependence on the distance between the antennas.", "author_names": [ "R Sharma", "Philipp Durrenfeld", "M Ranjbar", "Randy K Dumas", "Johan Akerman", "Pranaba Kishor Muduli" ], "corpus_id": 52858705, "doc_id": "52858705", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Modulation Rate Study in a Spin Torque Oscillator Based Wireless Communication System", "venue": "IEEE Transactions on Magnetics", "year": 2015 }, { "abstract": "Abstract An important property of spin torque nano oscillators (STNOs) is their ability to produce a frequency modulated (FM) signal, which is very critical for communication applications. We here demonstrate a novel single sideband (SSB) modulation phenomenon using a magnetic tunnel junction (MTJ) based STNO, which saves transmission bandwidth and in principle should minimize attenuation for wireless communication. Experimentally, lower single sidebands (LSSBs) have been successfully demonstrated over a wide range of modulation frequency, fm 150 MHz 1 GHz. The observed LSSBs are determined by the intrinsic properties of the device, which can be modeled well by a nonlinear frequency and amplitude modulation formulation and reproduced in macrospin simulations. Moreover, our macrospin simulation results show that the range of modulation current and modulation frequency for generating SSBs can be controlled by the field like torque and biasing conditions.", "author_names": [ "Raghav Sharma", "Naveen Sisodia", "Ezio Iacocca", "Ahmad A Awad", "Johan Akerman", "Pranaba Kishor Muduli" ], "corpus_id": 37158574, "doc_id": "37158574", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "A high speed single sideband generator using a magnetic tunnel junction spin torque nano oscillator", "venue": "Scientific Reports", "year": 2017 }, { "abstract": "Spin transfer torque nano oscillators (STNOs) based on magnetoresistance and spin transfer torque effects find potential applications in miniaturized wireless communication devices. Using the non coherent non equilibrium Green's function spin transport formalism self consistently coupled with the stochastic Landau Lifshitz Gilbert Slonczewski's equation and the Poisson's equation, we elucidate the role of elastic phase breaking on the proposed STNO design featuring double barrier resonant tunneling. Demonstrating the immunity of our proposed design, we predict that despite the presence of elastic dephasing, the resonant tunneling magnetic tunnel junction structures facilitate oscillator designs featuring a large enhancement in microwave power up to 8mW delivered to a 50O load.", "author_names": [ "Abhishek A Sharma", "Ashwin A Tulapurkar", "Bhaskaran Muralidharan" ], "corpus_id": 103759329, "doc_id": "103759329", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Role of phase breaking processes on resonant spin transfer torque nano oscillators", "venue": "", "year": 2018 }, { "abstract": "Spin orbit torque nano oscillators based on bilayers of ferromagnetic and nonmagnetic metals are ultra compact current controlled microwave signal sources. They are attractive for practical applications such as microwave assisted magnetic recording, neuromorphic computing, and chip to chip wireless communications. However, a major drawback of these devices is low output microwave power arising from the relatively small anisotropic magnetoresistance of the ferromagnetic layer. Here we experimentally show that the output power of a spin orbit torque nano oscillator can be significantly enhanced without compromising its structural simplicity. Addition of a ferromagnetic reference layer to the oscillator allows us to employ current in plane giant magnetoresistance to boost the output power of the device. This enhancement of the output power is a result of both large magnitude of giant magnetoresistance compared to that of anisotropic magnetoresistance and their different angular dependencies. Our results hold promise for practical applications of spin orbit torque nano oscillators. Spin orbit torque driven oscillators, such as spin Hall oscillators, form a class of devices that are intensively studied due to potential practical applications in spintronics. Here, the authors modify the conventional ferromagnetic/nonmagnetic stack to include an additional ferromagnetic layer and leverage the giant magnetoresistance effect to enhance the direct conversion of an in plane driving current into the microwave output signal.", "author_names": [ "Jen-Ru Chen", "Andrew Smith", "Eric Arturo Montoya", "Jia Grace Lu", "Ilya N Krivorotov" ], "corpus_id": 225058860, "doc_id": "225058860", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Spin orbit torque nano oscillator with giant magnetoresistance readout", "venue": "", "year": 2020 } ]

[ { "abstract": "The present research demonstrates the fabrication and comparative performance of GaN based metal semiconductor metal (MSM) ultraviolet (UV) photodetector on sapphire substrate. The MSM device has been fabricated with gold (Au) in an inter digitized electrode (IDE) form with different geometry on molecular beam epitaxially (MBE) grown GaN. The current voltage characteristics shows the minimum dark current of 68 nA and 40 nA and photocurrent of 24.5 \\mu$A and 9.02 \\mu$A for rectangular asymmetric (RA) and circular asymmetric (CA) geometry respectively. The room temperature characterization was performed under the illumination of 365 nm light at the applied voltage of 5V. The responsivity and efficiency enhanced by almost three times by circular geometry due to the reduced two dimensional and three dimensional electric field distribution effects in CA IDE.", "author_names": [ "Indu Kumari", "Santu Nandi", "Ankush Bag" ], "corpus_id": 174820713, "doc_id": "174820713", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Performance Evaluation of GaN based Selective UV Photodetector by Varying Metal Semiconductor Metal Geometry", "venue": "2019 Electron Devices Technology and Manufacturing Conference (EDTM)", "year": 2019 }, { "abstract": "Optoelectronic properties of nonpolar a plane GaN are superior along the [0002] azimuth direction compared to other azimuth directions. We have grown a GaN on r sapphire, and interdigitated electro.", "author_names": [ "Rohit Pant", "Deependra Kumar Singh", "Arun Malla Chowdhury", "Basanta Roul", "Karuna Kar Nanda", "Saluru Baba Krupanidhi" ], "corpus_id": 213280456, "doc_id": "213280456", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Highly Responsive, Self Powered a GaN Based UV A Photodetectors Driven by Unintentional Asymmetrical Electrodes", "venue": "", "year": 2020 }, { "abstract": "Abstract This study demonstrates a novel, simple, and process compatible approach to fabricate UV photodetectors (PDs) based on an asymmetric metal semiconductor metal (MSM) structure, with ZnO nanoflowers (NFs) as the active layer. A network of silver nanowires (AgNWs) is used as a low resistivity transparent electrode. The MSM UV PDs based on AgNWs/ZnONFs/AgNWs showed low dark current of the order of nA and a photo to dark current ratio of two orders of magnitude at 3 V and more than 3 orders of magnitude at 3 V of asymmetric MSM UV PDs based on AgNWs/ZnONFs/AgNWs with a source (S) and drain (D) channel width of 570 mm. The UV sensitivity and responsivity at 0 V of the device with the wider S/D channel was as high as 6.34 x 104 and 9.4 x 10 3 AW 1, respectively. The findings suggest that UV PDs based on ZnONFs with asymmetric Ag network electrodes with ZnONFs hold promise for use in future optoelectronic devices.", "author_names": [ "Manoj Kumar", "Hakyung Jeong", "Dongjin Lee" ], "corpus_id": 205234592, "doc_id": "205234592", "n_citations": 12, "n_key_citations": 1, "score": 0, "title": "UV photodetector with ZnO nanoflowers as an active layer and a network of Ag nanowires as transparent electrodes", "venue": "Superlattices and Microstructures", "year": 2019 }, { "abstract": "Abstract A scheme illustrating electrode engineering in metal semiconductor metal geometry is employed for fabricating GaN based high performance ultraviolet photodetectors. The effect of different metal semiconductor (Au, Ti/Al and Al) junctions on photon assisted charge carrier transport and the current conduction is explored. Depending upon work function of the metals, barrier height varies which contributed towards different characteristics of the device revealing linear and non linear behaviour of the electrical measurements from the non rectifying and rectifying contact at the metal semiconductor interface respectively. A maximum photoresponsivity efficiency of 280.4 mA/W and 107.04% respectively, under 5 V applied bias in the visible blind region was measured from the device with rectifying Au electrodes. While, the photoresponsivity values of 219 mA/W and 200 mA/W under the same bias has been achieved from devices measured with near Ohmic contacts using Ti/Al and Al electrodes, respectively. The enhancement in detector's performance with Au electrode has been attributed to the built in electric field as well as the presence of internal gain which can promote efficient transport of charge carriers through the metal semiconductor interface. Thus, an approach has been adopted to enhance the photoresponsivity of the fabricated GaN based optoelectronic devices which could be utilized for wide range of industrial, military, environmental and biological applications.", "author_names": [ "Neha Aggarwal", "Shibin Krishna", "Shubhendra Kumar Jain", "Arzoo Arora", "Lalit N Goswami", "Alka Jyoti Sharma", "Sudhir Husale", "A Gundimeda", "Govind Gupta" ], "corpus_id": 139823441, "doc_id": "139823441", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Impact on photon assisted charge carrier transport by engineering electrodes of GaN based UV photodetectors", "venue": "Journal of Alloys and Compounds", "year": 2019 }, { "abstract": "Abstract In this work, we have investigated the potential of Pt nanoparticles in modification the surface of b Ga2O3 layer, which improved the performance of b Ga2O3 based device with a novel asymmetric metal semiconductor metal (MSM) structure. The results shown that the disadvantage of high dark current in traditional MSM detector can be overcome by the novel asymmetric MSM detector and the Pt nanoparticles can remarkably enhance the generation of photogenerated carriers via formation of the local surface plasmon resonance effect. As a result, the obtained device has a high responsivity of 29.08 A/W, an excellent detectivity (D* of 2.16x1011 Jones and a high normalized photocurrent to dark current ratio (NPDR) of 5.156x106 mW 1cm2, exhibiting an increase by 88.5% 677% and 3024.8% compared to pristine device. At last, the energy band theory and the finite difference time domain (FDTD) calculation were used to explain the mechanism of device performance improvement. These results of our study provide an effective method for fabricating high performance solar blind photodetector and pave the way for the potential application of Pt nanoparticles in the field of deep UV photodetector.", "author_names": [ "Jian Lou", "Zhuo Wang", "Siwei Ji", "Jiajie Chen", "Yanfei Hu", "Lei Yuan", "Yuming Zhang", "Renxu Jia" ], "corpus_id": 233683502, "doc_id": "233683502", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Surface modification of b Ga2O3 layer using pt nanoparticles for improved deep UV photodetector performance", "venue": "", "year": 2021 }, { "abstract": "Fabrication of very thin GaN ultraviolet photodetectors on Si (111) substrate integrated with asymmetric (Pt Ag, Pt Cr) metal semiconductor metal (MSM) structure have been illustrated. Designed GaN photodetection device displays significant enhancement in responsivity for asymmetric (Pt Ag) MSM structure (280 mA/W) in comparison to symmetric (Pt Pt) MSM structure (126 mA/W) at 10 V bias. The fabricated asymmetric and symmetric devices also exhibit fast response time in the range of 30 59 ms. The enhancement in responsivity using asymmetric MSM structure ascribed to large difference in work function which lead to change in Schottky barrier height of the metal semiconductor junction. Additionally, power dependent photoresponse analysis of GaN asymmetric (Pt Ag) ultraviolet photodetector was showing a responsivity of 116 mA/W at low optical power of 1 mW. Such GaN asymmetric MSM ultraviolet photodetectors having high responsivity can extensively be used for low power, high speed ultraviolet photo detection applications.", "author_names": [ "Shubhendra Kumar Jain", "Neha Aggarwal", "Shibin Krishna", "Rahul Kumar", "Sudhir Husale", "Vinay Gupta", "Govind Gupta" ], "corpus_id": 139808711, "doc_id": "139808711", "n_citations": 29, "n_key_citations": 0, "score": 1, "title": "GaN UV photodetector integrated with asymmetric metal semiconductor metal structure for enhanced responsivity", "venue": "Journal of Materials Science: Materials in Electronics", "year": 2018 }, { "abstract": "Near ultraviolet (NUV) light emitting diodes (LEDs) have been used in several potential applications such as UV curing and biochemical sensors. However, the internal quantum efficiency (IQE) of NUV LEDs is still a crucial issue. To improve the IQE, in this paper, an asymmetric triangular multiple quantum well (MQW) structure was used, which exhibited a higher emission efficiency and lower efficiency droop with nitrogen face oriented inclination. This is in contrast to the trend observed in blue LEDs. Furthermore, we demonstrated that holes are more confined in MQWs with nitrogen face oriented inclination than in MQWs with gallium face oriented inclination. Moreover, simulations revealed that the IQE improved by approximately 32% compared with that of symmetric square MQW NUV LEDs; this trend was also confirmed through experimental results. The external quantum efficiency of thin film flip chip LEDs with nitrogen face oriented inclination MQWs was 52%", "author_names": [ "Heng Li", "Chia Jui Chang", "Shiou-Yi Kuo", "Haocheng Wu", "Huamao Huang", "Tien-Chang Lu" ], "corpus_id": 54464182, "doc_id": "54464182", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Improved Performance of Near UV GaN Based Light Emitting Diodes With Asymmetric Triangular Multiple Quantum Wells", "venue": "IEEE Journal of Quantum Electronics", "year": 2019 }, { "abstract": "Self powered photodetectors have demonstrated potential for developing future wireless and implantable devices. Herein, we present a self powered UV photodetector with an ultrahigh photoresponse based on vertically oriented and high crystalline quality n type GaN nanorod arrays: poly(methyl methacrylate)/p Si heterojunction. Benefiting from the highly efficient separation and transport of photoexcited electron hole pairs, significant improvements in photoresponsivity are experimentally obtained. In a zero biased self powered detection mode, a 6.7AW 1 responsivity and 2.68x1013 Jones detectivity are achieved under 355 nm light illumination, and the response time is as low as 0.29/3.07 ms (rise/fall times)", "author_names": [ "Yulin Zheng", "Xin Tang", "Yuhui Yang", "Wenliang Wang", "Guoqiang Li" ], "corpus_id": 221464729, "doc_id": "221464729", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Vertically aligned GaN nanorod arrays/p Si heterojunction self powered UV photodetector with ultrahigh photoresponsivity.", "venue": "Optics letters", "year": 2020 }, { "abstract": "A simplistic design of a self powered UV photodetector device based on hybrid reduced graphene oxide (r GO)/gallium nitride (GaN) is demonstrated. Under zero bias, the fabricated hybrid photodetector shows a photosensivity of ~85% while the ohmic contact GaN photodetector with an identical device structure exhibits only ~5.3% photosensivity at 350 nm illumination (18 mW/cm2) The responsivity and detectivity of the hybrid device were found to be 1.54 mA/W and 1.45 x 1010 Jones (cm Hz 1/2 W 1) respectively, at zero bias with fast response (60 ms) recovery time (267 ms) and excellent repeatability. Power density dependent responsivity and detectivity revealed ultrasensitive behaviour under low light conditions. The source of the observed self powered effect in the hybrid photodetector is attributed to the depletion region formed at the r GO and GaN quasi ohmic interface.", "author_names": [ "N Guru Prakash", "Manjri Singh", "Gaurav Kumar", "Arun Barvat", "Kritika Anand", "Prabir Pal", "Surinder P Singh", "Suraj P Khanna" ], "corpus_id": 119486542, "doc_id": "119486542", "n_citations": 53, "n_key_citations": 1, "score": 0, "title": "Ultrasensitive self powered large area planar GaN UV photodetector using reduced graphene oxide electrodes", "venue": "", "year": 2016 }, { "abstract": "Hybrid systems based on the combination of crystalline bulk semiconductors with 2D crystals are identified as promising heterogeneous structures for new optoelectronic applications. The direct integration of III V semiconductors on 2D materials is very attractive to make practical devices but the preservation of the intrinsic properties of the underlying 2D materials remains a challenge. In this work, we study the direct epitaxy of self organized GaN crystals on graphene. We demonstrate that severe metal organic chemical vapor deposition growth conditions of GaN (chemically aggressive precursors and high temperatures) are not detrimental to the structural quality and the charge carrier mobility of the graphene base plane. Graphene can therefore be used both as an efficient sensitive material and as a substrate for GaN epitaxy to make a self assembled UV photodetector. A responsivity as high as 2 A W 1 is measured in the UV A range without any further postprocessing compared to simple deposition of contact electrodes. Our study opens the way to build new self assembled 2D/III V hybrid optoelectronic devices by direct epitaxy.", "author_names": [ "Timotee Journot", "Vincent Bouchiat", "B Gayral", "Jean Dijon", "Berangere Hyot" ], "corpus_id": 13693238, "doc_id": "13693238", "n_citations": 27, "n_key_citations": 0, "score": 0, "title": "Self Assembled UV Photodetector Made by Direct Epitaxial GaN Growth on Graphene.", "venue": "ACS applied materials interfaces", "year": 2018 } ]

[ { "abstract": "Measurement of moisture at ppm or ppb level is very difficult and the fabrication of such sensors at low cost is always challenging. High sensitivity is an important parameter for trace level (ppm) humidity sensors. Anelectronic detection circuit for interfacing the humidity sensor with high sensitivity requires a simple hardware circuit with few active devices. The recent trends for increasing the sensitivity include fabricating nanoporous film with a very large surface area. In the present work, the sensitivity of a parallel plate capacitive type sensor with metal oxide sensing film has been significantly improved with an aim to detect moisture from 3 to 100 ppm in the industrial process gases used to fabricate semiconductors and other sensitive electronic devices. The sensitivity has been increased by (i) fabricating a nanoporous film of aluminum oxide using the sol gel method and (ii) increasing the cross sectional area of a parallel plate capacitor. A novel double sided capacitive structure has been proposed where two capacitors have been fabricated one on the top and one on the bottom side of a flat alumina substrate and then the capacitors are connected in parallel. The structure has twice the sensitivity of a single sensor in the same ppm range but the size of the structure remains unchanged. The important characteristics of the sensors such as the sensitivity (S D C D p p m x 100 the response time (tr) and the recovery time (tc) are determined and compared with a commercial SHAW, UKdew point meter. The fabricated double sided sensor has comparable sensitivity (S 100% tr (s) 28, tc (s) 40) with the commercial meter (S 100.5% tr (s) 258) but has a faster response time. The proposed method of sensitivity enhancement is simple, and mass producible.", "author_names": [ "Lokesh Kumar", "Tarikul Islam", "Subhas Chandra Mukhopadhyay" ], "corpus_id": 54695847, "doc_id": "54695847", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Sensitivity Enhancement of a PPM Level Capacitive Moisture Sensor", "venue": "", "year": 2017 }, { "abstract": "In the present study a real time capacitive sensor based on a capacitance step method is designed, developed and applied on measuring the liquid level by immersion. The capacitive sensor consists of two electrodes from copper plated phenolite plates separated by a gap distance and mounted inside a non conductive storage tank. Water is used as the dielectric material. The analyzed sensor behavior with liquid level variation is semi linear and obtained in function of the output voltage variation by using proper signal conditioning circuit. For converting the voltage variation into level variation, a parallel R C circuit is used instead of conventional bridge circuit. Under suitable parameter settings it provided good reading accuracy. The experimental results demonstrate the high efficiency of the proposed model, which confirm the satisfactory performance of the capacitive sensor for liquid level measurement. The sensor presents an excellent ease of construction and installation, linked to the good measurements precision and high autonomy of system operation. The behavior experiments under different salt concentrations show that the water chemical composition does not interfere on the sensor operation. The proposed model exhibits a promising employment in several applications, such as control equipment for irrigation, biomedical area in the interaction between antibody antigen or protein DNA, aerospace and pharmaceutical industry, gas sensors, and automation solutions.", "author_names": [ "R T Bento", "Roger W O Silva", "Lucas Alves Dias", "Andre Ferrus Filho", "Antonio Pitta" ], "corpus_id": 189932742, "doc_id": "189932742", "n_citations": 3, "n_key_citations": 0, "score": 1, "title": "Design, development and application of a real time capacitive sensor for automatically measuring liquid level", "venue": "SN Applied Sciences", "year": 2019 }, { "abstract": "Liquid level measurement is important requirement for building and industrial applications. One of the most popular methods for level measurement is the capacitive sensor. Most of the capacitive sensors are contact type which suffer from frequent maintenance, and drift of the sensor output. Present paper proposes a simple noncontact interdigitated fringing field capacitance sensor for liquid level measurement. Three different interdigitated (IDT) sensors have been designed, simulated (finite element method) and fabricated to measure water level from 0 to 40 mm. The capacitance value of all the three sensors vary almost linearly with the variation of liquid level. Experimental results show that the sensitivity of the 1 5 1 IDT sensor is 0.0398 pF/mm. The sensor is capable to detect water level with resolution of 0.1 mm", "author_names": [ "Tarikul Islam", "Om Prakash Maurya" ], "corpus_id": 212703639, "doc_id": "212703639", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Design and fabrication of non contact fringing field capacitive sensor for liquid level measurement", "venue": "2019 IEEE 16th India Council International Conference (INDICON)", "year": 2019 }, { "abstract": "Present work describes the design and development of nonsubmersible capacitive sensor for liquid level detection. The prototype implementation is done using glass container. Aluminum strips on the outer surface of the container forms the capacitor. The change in water level inside the container, changes the capacitance value. This changes the signal frequency which is analyzed using microcontroller. Hence, this proposed prototype successfully detects the change in level of water without submersing the sensor inside the container.", "author_names": [ "", "Amit Patwardhan", "P N Vishwanathan", "Jayant Pawar", "Ashish kumar Patel", "Rabinder Henry", "Pratik More" ], "corpus_id": 174784875, "doc_id": "174784875", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Development of Non Submersible Capacitive Sensor for Water Level Detection", "venue": "", "year": 2019 }, { "abstract": "Hoppers and silos are the integrated part of various industrial processes. Hoppers or silos are used mainly as a temporary storage of the product or by product from the industrial processes. Level measurement in hoppers is a crucial task due to temperature and dusty environment. Various techniques like optical laser based sensors, ultrasonic sensors, strain gauge based sensors etc. are used for level measurement in the hoppers/silos. But for cement or ash level measurement, due to dusty environment ultrasonic sensors and optical sensors are not advisable. Strain gauge based sensors are also not advisable as it work on the physical deformation of the sensor so it has relatively small life cycle. A non contact type capacitive sensor design is proposed and experimentally evaluated for level measurement in hopper/silos. The calculation for the non parallel portion of the hopper is also presented in this work. The present design in free from any parasitic capacitances and the outer metallic body of the hopper is used as shield for the capacitive sensor. The experiments are performed for cement clinkers and fly ash and the results are presented.", "author_names": [ "Amithab Pal", "Urandur Pavan Kalyan", "Ch Harika", "B Vasuki" ], "corpus_id": 211211862, "doc_id": "211211862", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Capacitive Sensor for Level Measurement in Hopper/Silos Experimental Evaluation", "venue": "2019 2nd International Conference on Intelligent Computing, Instrumentation and Control Technologies (ICICICT)", "year": 2019 }, { "abstract": "BACKGROUND: Drinking water has several advantages that have already been established, such as improving blood circulation, reducing acid in the stomach, etc. However, due to people not noticing the amount of water they consume every time they drink, most people drink less water than the recommended daily allowance. OBJECTIVE: In this paper, a capacitive sensor for developing an automatic tumbler to measure water level is proposed. Different than in previous studies, the proposed capacitive sensor was separated into two sets: the main sensor for measuring the water level in the tumbler, and the reference sensor for measuring the incremental level unit. METHODS: In order to confirm the feasibility of the proposed idea, and to optimize the shape of the sensor, a 3D model of the capacitive sensor with the tumbler was designed and subjected to Finite Element Analysis (FEA) simulation. According to the simulation results, the electrodes were made of copper and assembled in a tumbler manufactured by a 3D printer. The tumbler was filled with water and was subjected to experiments in order to assess the sensor's performance. RESULTS: The comparison of experimental results to the simulation results shows that the measured capacitance value of the capacitive sensor changed linearly as the water level varied. This proves that the proposed sensor can accurately measure the water level in the tumbler. Additionally, by use of the curve fitting method, a compensation algorithm was found to match the actual level with the measured level. CONCLUSIONS: The experimental results proved that the proposed capacitive sensor is able to measure the actual water level in the tumbler accurately. A digital control part with micro processor will be designed and fixed on the bottom of the tumbler for developing a smart tumbler.", "author_names": [ "Qun Wei", "Mi-Jung Kim", "Jong-Ha Lee" ], "corpus_id": 46887654, "doc_id": "46887654", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Development of capacitive sensor for automatically measuring tumbler water level with FEA simulation", "venue": "Technology and health care official journal of the European Society for Engineering and Medicine", "year": 2018 }, { "abstract": "Paper presents a technique for simultaneous measurement of liquid temperature along with level of liquid using capacitive level sensor and estimators/ soft sensors. The objective of the proposed work is to develop an estimator for measuring the liquid temperature in a process tank by analyzing the available capacitive level sensor. Input output behavior of the capacitive level sensor is analyzed for variation in liquid level and temperature variations. A non parametric soft sensor is designed using artificial neural network and fuzzy logic techniques are used to compute the relation between the capacitive level sensor outputs for variations in liquid temperature. The designed measurement technique is validated by performing the experiment in simulation and on practical setup. Results obtained by the technique shows successful implementation of proposed soft sensor.", "author_names": [ "Santhosh Kv", "Manik Gupta" ], "corpus_id": 54435229, "doc_id": "54435229", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Simultaneous Measurement of Liquid Level and Temperature Using Capacitive Sensor", "venue": "2018 2nd International Conference on Trends in Electronics and Informatics (ICOEI)", "year": 2018 }, { "abstract": "Ink printing is utilized to develop a coplanar capacitive senor with microscale electrodes, which exhibits high sensitivity. The sensor's capacitance has been theoretically and experimentally correlated to the water resistivity. As a cost effective, portable and reusable sensor, its application for water level measuring and quality monitoring has been demonstrated.", "author_names": [ "Qiang Yang", "Andrew Junfang Yu", "James L Simonton", "Gaoqiang Yang", "Yeshi Dohrmann", "Zhenye Kang", "Yifan Li", "Jingke Mo", "Feng-Yuan Zhang" ], "corpus_id": 136108652, "doc_id": "136108652", "n_citations": 14, "n_key_citations": 1, "score": 0, "title": "An inkjet printed capacitive sensor for water level or quality monitoring: investigated theoretically and experimentally", "venue": "", "year": 2017 }, { "abstract": "In this paper, characterization of sensitive contact less coplanar capacitive liquid level sensors realized by polymer thick film technology is presented. It was found out that polymer thick film coplanar capacitive sensors are suitable for use in liquid level sensing application realized by contactless sensing method. Principle of measurement by using contact less capacitive sensing method and performance of realized liquid level sensors are described in this paper. Design optimization of various geometric dimension of comb sensor structures was compared and analyzed for easy construction of very sensitive contact less coplanar capacitive liquid level sensor. Thick film coplanar capacitive sensor is suitable, cost effective and reusable alternative for contact less level measurement of various liquids with different dielectric constant.", "author_names": [ "Alena Pietrikova", "Samuel Zuk", "Igor Vehec" ], "corpus_id": 201740913, "doc_id": "201740913", "n_citations": 3, "n_key_citations": 1, "score": 0, "title": "Coplanar Capacitive Liquid Level Sensor", "venue": "2019 42nd International Spring Seminar on Electronics Technology (ISSE)", "year": 2019 }, { "abstract": "Abstract This paper presents the design and fabrication of a liquid level measurement system based on a grounded cylindrical capacitive sensor for conductive liquids. Fabrication of the cylindrical capacitive sensor is performed with a novel approach of shielded cable. The inner conductor of shielded cable is connected to ground and the outer conductor is used to measure the liquid level. The relationship between the capacitance value of the cylindrical capacitive sensor and the liquid level is deduced by the analysis and calculation of physical parameters. Moreover, a backward difference calculation is adopted in order to offset the effects of the parasitic capacitance. The performance of the system has been experimentally tested in both grounded metallic and plastic containers. The experimental results show that the nonlinear error is smaller than 5 mm over a range of 90 cm. Over a wide measuring range of 200 cm, the liquid level measurement system has a nonlinear error smaller than 1.35 cm.", "author_names": [ "Bao-quan Jin", "Zeyu Zhang", "Hong-juan Zhang" ], "corpus_id": 108456383, "doc_id": "108456383", "n_citations": 47, "n_key_citations": 4, "score": 0, "title": "Structure design and performance analysis of a coaxial cylindrical capacitive sensor for liquid level measurement", "venue": "", "year": 2015 } ]

[ { "abstract": "Much of the mechanical strain in semiconductor devices can be relieved when they are made on compliant substrates. We demonstrate this strain relief with amorphous silicon thin film transistors made on 25 /spl mu/m thick polyimide foil, which can be bent to radii of curvature R down to 0.5 mm without substantial change in electrical characteristics.", "author_names": [ "Helena Gleskova", "Sigurd Wagner" ], "corpus_id": 42607654, "doc_id": "42607654", "n_citations": 84, "n_key_citations": 4, "score": 1, "title": "Amorphous silicon thin film transistors on compliant polyimide foil substrates", "venue": "IEEE Electron Device Letters", "year": 1999 }, { "abstract": "Flexible electronics will have inorganic devices grown at elevated temperatures on free standing foil substrates. The thermal contraction mismatch between the substrate and the deposited device films, and the built in stresses in these films, cause curving and a change in the in plane dimensions of the workpiece. This change causes misalignment between the device layers. The thinner and more compliant the substrate, the larger the curvature and the misalignment. We model this situation with the theory of a bimetallic strip, which suggests that the misalignment can be minimized by tailoring the built in stress introduced during film growth. Amorphous silicon thin film transistors (a Si:H TFTs) fabricated on stainless steel or polyimide (PI) (Kapton E(r) foils need tensile built in stress to compensate for the differential thermal contraction between the silicon films and the substrate. Experiments show that by varying the built in stress in just one device layer, the gate silicon nitride (SiNx) one can reduce the misalignment between the source/drain and the gate levels from ~400 parts per million to ~100 parts per million.", "author_names": [ "Helena Gleskova", "I-Chun Cheng", "Sigurd Wagner", "Zhigang Suo" ], "corpus_id": 109232683, "doc_id": "109232683", "n_citations": 14, "n_key_citations": 1, "score": 0, "title": "Mechanical theory of the film on substrate foil structure: curvature and overlay alignment in amorphous silicon thin film devices fabricated on free standing foil substrates", "venue": "", "year": 2009 }, { "abstract": "We have fabricated high performance amorphous silicon thin film transistors (a Si:H TFTs) on 2 mil. (51 mm) thick polyimide foil substrates. The TFT structure was deposited by r.f. excited plasma enhanced chemical vapor deposition (PECVD) All TFT layers, including the gate silicon nitride, the undoped, and the n+ amorphous silicon were deposited at a substrate temperature of 150 degC. The transistors have inverted staggered back channel etch structure. The TFT off current is approximately 10 12 A, the on off current ratio is >107, the threshold voltage is 3.5 V, the sub threshold slope is approximately 0.5 V/decade, and the linear regime mobility is approximately 0.5 cm2 V 1 s 1. We compare the mechanical behavior of a thin film on a stiff and on a compliant substrate. The thin film stress can be reduced to one half by changing from a stiff to a compliant substrate. A new equation is developed for the radius of curvature of thin films on compliant substrates.", "author_names": [ "Helena Gleskova", "Sigurd Wagner", "Zhigang Suo" ], "corpus_id": 98564986, "doc_id": "98564986", "n_citations": 70, "n_key_citations": 0, "score": 0, "title": "a Si:H TFTs made on polyimide foil by PE CVD at 150 degC", "venue": "", "year": 1998 }, { "abstract": "Large area electronic circuits on thin foil substrates can be made with techniques adapted from conventional printing. Conventional printing can provide a resolution and an overlay registration of 10 mm and 5 mm, respectively, which will allow making thin film transistors (TFTs) at densities above 10 000 per square centimeter. An early example is the use of laser printed toner etch masks for the fabrication of amorphous silicon TFTs. Patterned devices can be made by direct printing, as demonstrated by the jet printing of the active polymer for organic light emitting diodes (OLEDs) Paper thin foils of glass, steel, and polyimide can serve as substrates for making TFTs with characteristics comparable to those made on glass plates. Materials options for thin foil substrates are described. A study of the mechanics of films on stiff and compliant foil substrates shows that particularly rugged and flexible device structures can be made when the foils are very thin. Integrating OLEDs with thin film transistors on steel foil substrates provides an early example of 3 D integrated components for macroelectronics.", "author_names": [ "Sigurd Wagner", "Helena Gleskova", "James C Sturm", "Zhigang Suo" ], "corpus_id": 134107768, "doc_id": "134107768", "n_citations": 29, "n_key_citations": 0, "score": 0, "title": "Novel processing technology for microelectronics", "venue": "", "year": 2000 }, { "abstract": "We report the successful fabrication of high quality a Si:H thin film transistors (TFTs) on stainless steel foil substrates. TFTs with an inverted staggered structure were grown on 200 /spl mu/m thick stainless steel foil. These TFTs show typical ON/OFF current ratios of 10/sup 7/ OFF currents on the order of 10/sup 12/ A, good linear and saturation current behavior, subthreshold slopes of 0.5 V/decade, and linear channel mobilities of 0.5 cm/sup 2//V. In addition, we have demonstrated that these TFTs are capable of withstanding significant mechanical shocks, as well as macroscopic deformation of the substrate, while remaining functional. This work demonstrates that transistor circuits can be made on a flexible, nonbreakable substrate. Such circuits would be highly useful in reflective or emissive displays, and in other applications that require rugged macroelectronic circuits.", "author_names": [ "Steven D Theiss", "Sigurd Wagner" ], "corpus_id": 7515378, "doc_id": "7515378", "n_citations": 78, "n_key_citations": 1, "score": 0, "title": "Amorphous silicon thin film transistors on steel foil substrates", "venue": "IEEE Electron Device Letters", "year": 1996 }, { "abstract": "We have fabricated TFTs of nanocrystalline silicon (nc Si) at 150degC on clear polymer substrates (coefficients of thermal expansion, a~45 to 55ppm/K) on Kapton(r) 200E (a=17ppm/K) and on Corning 1737 glass (a=3ppm/K) for comparison. Because thermally stable polymers, such as Kapton(r) 200E polyimide, have glass transition temperatures as high as 325degC, they are candidates for direct substitution of display glass. The stresses developed in the substrate and device layers, due to a, are reduced by decreasing the thickness of the active layers, by cutting the layers into islands separated by exposed substrate, and by designing stresses, via plasma conditions, into the SiNx passivating layers. By using these three techniques we have made nc Si TFTs on high Tg, and high a, clear polymer foils with electron mobilities of up to 18cm 2 /Vs. When integrated with bottom emitting organic light emitting diodes, such devices will allow for a 10x reduction in pixel TFT areas, compared to TFTs of amorphous silicon.", "author_names": [ "Alex Z Kattamis", "I-Chun Cheng", "Ke Long", "James C Sturm", "Sigurd Wagner" ], "corpus_id": 18502793, "doc_id": "18502793", "n_citations": 8, "n_key_citations": 5, "score": 0, "title": "Nanocrystalline Silicon Thin Film Transistors on Optically Clear Polymer Foil Substrates", "venue": "", "year": 2005 }, { "abstract": "We have developed a 150degC technology for amorphous silicon thin film transistors (a Si:H TFTs) on polyimide substrates deposited by plasma enhanced chemical vapor deposition. The silicon nitride gate dielectric and the a Si:H channel material were tailored to provide the least leakage current and midgap defect density, respectively. In addition, we conducted experiments on the TFT structure and fabrication with the aim of obtaining high electron mobility. TFTs with back channel etch and channel passivated structures were fabricated on glass or 51 mm thick polyimide foil. The a Si:H TFTs have an on/off current ratio of ~10 7 and an electron mobility of ~0.7 cm 2/V s.", "author_names": [ "Helena Gleskova", "Sigurd Wagner", "Vladimir Gasparik", "P Kovac" ], "corpus_id": 56333904, "doc_id": "56333904", "n_citations": 64, "n_key_citations": 2, "score": 0, "title": "150degC Amorphous Silicon Thin Film Transistor Technology for Polyimide Substrates", "venue": "", "year": 2001 }, { "abstract": "Thin film transistors (TFTs) were fabricated on polyimide and glass substrates at low temperatures using microwave ECR CVD deposited amorphous and nanocrystalline silicon as active layers. The amorphous Si TFT fabricated at 200 /spl deg/C on the polyimide foil had a saturation region field effect mobility of 4.5 cm/sup 2//V s, a linear region mobility of 5.1 cm/sup 2//V s, a threshold voltage of 3.7 V, a subthreshold swing of 0.69 V/decade, and an ON/OFF current ratio of 7.9 /spl times/ 10/sup 6/ This large mobility and high ON/OFF current ratio were attributed to the high quality channel materials with less dangling bond defect states. Nanocrystalline Si TFTs fabricated on glass substrates at 400 /spl deg/C showed a saturation region mobility of 14.1 cm/sup 2//V s, a linear region mobility of 15.3 cm/sup 2//V s, a threshold voltage of 3.6 V, and an ON/OFF current ratio of 6.7 /spl times/ 10/sup 6/ TFT performance was mostly independent of substrate type when fabrication conditions were the same.", "author_names": [ "", "Wayne A Anderson" ], "corpus_id": 30423443, "doc_id": "30423443", "n_citations": 25, "n_key_citations": 1, "score": 0, "title": "Thin film transistors on plastic and glass substrates using silicon deposited by microwave plasma ECR CVD", "venue": "IEEE Electron Device Letters", "year": 2003 }, { "abstract": "We applied strain ranging from 1% compressive to ~0.3% tensile to a Si:H TFTs on polyimide foils by bending them inward or outward, or by stretching them in a microstrain tester. We also applied strain to a Si:H TFTs by deforming a flat substrate into a spherical dome. In each case, compression lowered and tension raised the on current and hence the electron field effect mobility. We conclude that compressive strain broadens both the valence and conduction band tails of the a Si:H channel material, and thus reduces the effective electron mobility. We show that the mobility can be used as an indicator of local mechanical strain.", "author_names": [ "Helena Gleskova", "P I Hsu", "Z Xi", "James C Sturm", "Zhigang Suo", "Sigurd Wagner" ], "corpus_id": 14558357, "doc_id": "14558357", "n_citations": 47, "n_key_citations": 3, "score": 0, "title": "Field effect mobility of amorphous silicon thin film transistors under strain", "venue": "", "year": 2004 }, { "abstract": "Flexible electronics and displays have attracted attention due to merits such as light weight, thin profiles, portability, and the ability to form conformable shapes, all of which allow novel applications. Lightweight, bendable thin film transistors (TFTs) are a must for the circuitry that drives such displays. Emerging TFT technology based on oxide semiconductors is promising for this application due to advantages such as high mobility in the amorphous phase, low processing temperatures, and relative compatibility with existing fabrication methods.1 4 Most reports on flexible oxide TFTs involve the use of steel foil substrates or of fabrication techniques such as lift off and shadow masking. These processes are relatively primitive and cannot be easily applied for mass production. Steel foils, meanwhile, suffer limited flexibility and issues of parasitic capacitance. Recently, there have been some reports of oxide TFTs on polyimide substrates, which are compatible with higher processing temperatures compared with other common plastic substrates. Although polyimides can, in general, withstand higher processing temperatures, to date most of these materials are tinted or not transparent, limiting applications in displays and other flexible electronics. We have used fully colorless and transparent polyimide based nanocomposite substrates to make high performance, highly flexible amorphous indium gallium zinc oxide (a IGZO) TFTs: see Figure 1.5 The lithographic and etching processes we use are compatible with existing TFT fabrication technologies. The first step is to coat smooth polyimide films tens of microns thick on glass substrates to which they adhere strongly. To Figure 1. (a) Flexible amorphous indium gallium zinc oxide thinfilm transistors (a IGZO TFTs) using a titanium/indium zinc oxide (Ti/ZnO) stacked electrode on a freestanding nanocomposite substrate. (b) Structure of the a IGZO TFT. SiNx: Silicon nitride.", "author_names": [ "Chih Wei Chien", "Cheng-han Wu" ], "corpus_id": 123752983, "doc_id": "123752983", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "High performance, highly rollable oxide thin film transistors", "venue": "", "year": 2012 } ]

[ { "abstract": "Room temperature, broadly tunable, electrically pumped semiconductor sources in the terahertz spectral range, similar in operation simplicity to diode lasers, are highly desired for applications. An emerging technology in this area are sources based on intracavity difference frequency generation in dual wavelength mid infrared quantum cascade lasers. Here we report terahertz quantum cascade laser sources based on an optimized non collinear Cherenkov difference frequency generation scheme that demonstrates dramatic improvements in performance. Devices emitting at 4 THz display a mid infrared to terahertz conversion efficiency in excess of 0.6 mW W( 2) and provide nearly 0.12 mW of peak power output. Devices emitting at 2 and 3 THz fabricated on the same chip display 0.09 and 0.4 mW W( 2) conversion efficiencies at room temperature, respectively. High terahertz generation efficiency and relaxed phase matching conditions offered by the Cherenkov scheme allowed us to demonstrate, for the first time, an external cavity terahertz quantum cascade laser source tunable between 1.70 and 5.25 THz.", "author_names": [ "Karun Vijayraghavan", "Yifan Jiang", "Min Jang", "Aiting Jiang", "Karthik Choutagunta", "Augustinas Vizbaras", "Frederic Demmerle", "Gerhard Boehm", "Markus-Christian Amann", "Mikhail A Belkin" ], "corpus_id": 14076495, "doc_id": "14076495", "n_citations": 159, "n_key_citations": 6, "score": 1, "title": "Broadly tunable terahertz generation in mid infrared quantum cascade lasers.", "venue": "Nature communications", "year": 2013 }, { "abstract": "", "author_names": [ "Yifan Jiang" ], "corpus_id": 210003083, "doc_id": "210003083", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Broadly tunable terahertz difference frequency generation in mid infrared quantum cascade lasers", "venue": "", "year": 2017 }, { "abstract": "We report a monolithic terahertz source made of an array of 10 electrically tunable mid infrared quantum cascade lasers with intra cavity terahertz difference frequency generation. Continuous tunability between 2 and 4 THz is demonstrated at room temperature.", "author_names": [ "Aiting Jiang", "Seungyong Jung", "Yifan Jiang", "Karun Vijayraghavan", "Jae Hyun Kim", "Mikhail A Belkin" ], "corpus_id": 118822384, "doc_id": "118822384", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Broadly tunable room temperature monolithic terahertz quantum cascade laser sources", "venue": "CLEO 2015", "year": 2015 }, { "abstract": "We report a monolithic terahertz source made of an array of 10 electrically tunable mid infrared quantum cascade lasers with intra cavity terahertz difference frequency generation. Continuous tunability between 2 and 4 THz is demonstrated at room temperature.", "author_names": [ "Aiting Jiang", "Seungyong Jung", "Yifan Jiang", "Karun Vijayraghavan", "Jaehyun Kim", "Mikhail A Belkin" ], "corpus_id": 12300292, "doc_id": "12300292", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Broadly tunable room temperature monolithic terahertz quantum cascade laser sources", "venue": "2015 Conference on Lasers and Electro Optics (CLEO)", "year": 2015 }, { "abstract": "We present room temperature broadly tunable external cavity terahertz sources based on Cherenkov intra cavity difference frequency generation in mid infrared quantum cascade lasers bonded with Si substrate. Laser chips are integrated into a Littrow type external cavity system. Devices demonstrate continuous THz emission tuning from 1.2 THz to 5.9 THz at room temperature with peak power output varying between 5 and 45 mW, depending on the operating frequency.", "author_names": [ "Yifan Jiang", "Karun Vijayraghavan", "Seungyong Jung", "Frederic Demmerle", "Gerhard Boehm", "Markus-Christian Amann", "Mikhail A Belkin" ], "corpus_id": 10050698, "doc_id": "10050698", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Broadly tunable external cavity terahertz source from 1.2~5.9 THz", "venue": "2014 39th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW THz)", "year": 2014 }, { "abstract": "Terahertz quantum cascade laser sources based on intra cavity difference frequency generation are currently the only room temperature mass producible diode laser like emitters of coherent 1 6 THz radiation. Device performance has improved dramatically over the past few years to reach milliwatt level power output and broad tuning from 1.2 to 5.9 THz, all at room temperature. Terahertz output in these sources originates from intersubband optical nonlinearity in the laser active region. Here we report the first comprehensive spectroscopic study of the optical nonlinearity and investigate its dependence on the mid infrared pump frequencies. Our work shows that the terahertz generation efficiency can vary by a factor of 2 or greater depending on the spectral position of the mid infrared pumps for a fixed THz difference frequency. We have also measured for the first time the linewidth for transitions between the lower quantum cascade laser states, which is critical for determining terahertz nonlinearity and predicting optical loss in quantum cascade laser waveguides.", "author_names": [ "Yifan Jiang", "Karun Vijayraghavan", "Seungyong Jung", "Aiting Jiang", "Jae Hyun Kim", "Frederic Demmerle", "Gerhard Boehm", "Markus-Christian Amann", "Mikhail A Belkin" ], "corpus_id": 18947165, "doc_id": "18947165", "n_citations": 30, "n_key_citations": 2, "score": 0, "title": "Spectroscopic Study of Terahertz Generation in Mid Infrared Quantum Cascade Lasers", "venue": "Scientific reports", "year": 2016 }, { "abstract": "We report the performance of room temperature terahertz sources based on intracavity difference frequency generation in mid infrared quantum cascade lasers with a dual upper state (DAU) active region. DAU active region design is theoretically expected to produce larger optical nonlinearity for terahertz difference frequency generation, compared to the active region designs of the bound to continuum type used previously. Fabricated buried heterostructure devices with a two section buried distributed feedback grating and the waveguide designed for Cherenkov difference frequency phase matching scheme operate in two single mode mid infrared wavelengths at 10.7 mm and 9.7 mm and produce terahertz output at 2.9 THz with mid infrared to terahertz conversion efficiency of 0.8 mW/W2 at room temperature.", "author_names": [ "Kazuue Fujita", "Masahiro Hitaka", "Akio Ito", "Tadataka Edamura", "Masamichi Yamanishi", "Seungyong Jung", "Mikhail A Belkin" ], "corpus_id": 1218906, "doc_id": "1218906", "n_citations": 48, "n_key_citations": 3, "score": 0, "title": "Terahertz generation in mid infrared quantum cascade lasers with a dual upper state active region", "venue": "", "year": 2015 }, { "abstract": "We discuss novel approaches to improve the tuning bandwidth and power output of terahertz (THz) sources based on difference frequency generation (DFG) in mid infrared quantum cascade lasers (QCLs) Using a double Littrow external cavity system, we experimentally demonstrate that both doubly resonant terms and optical rectification terms in the expression for the intersubband optical nonlinearity contribute to THz generation in DFG QCLs and report THz DFG QCLs with the optimized optical rectification terms. We also demonstrate a hybrid DFG QCL device on silicon that enables significant improvement on THz out coupling efficiency and results in more than 5 times higher THz output power compared to that of a reference device on its native semi insulating InP substrate. Finally, we report for the first time the THz emission linewidth of a free running continuous wave THz DFG QCL.", "author_names": [ "Seungyong Jung", "Yifan Jiang", "Jae Hyun Kim", "Luigi Consolino", "Saverio Bartalini", "Paolo De Natale", "Miriam Vitello", "Kazuue Fujita", "Masahiro Hitaka", "Akio Ito", "J D Kirch", "Dan Botez", "Frederic Demmerle", "Gerhard Boehm", "Markus-Christian Amann", "Mikhail A Belkin" ], "corpus_id": 125106793, "doc_id": "125106793", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Narrow linewidth ultra broadband terahertz sources based on difference frequency generation in mid infrared quantum cascade lasers", "venue": "OPTO", "year": 2017 }, { "abstract": "We discuss novel approaches to improve the tuning bandwidth and power output of terahertz (THz) sources based on difference frequency generation (DFG) in mid infrared quantum cascade lasers (QCLs) Using a double Littrow external cavity system, we experimentally demonstrate that both doubly resonant terms and optical rectification terms in the expression for the intersubband optical nonlinearity contribute to THz generation in DFG QCLs and report THz DFG QCLs with the optimized optical rectification terms. We also demonstrate a hybrid DFG QCL device on silicon that enables significant improvement on THz out coupling efficiency and results in more than 5 times higher THz output power compared to that of a reference device on its native semi insulating InP substrate. Finally, we report for the first time the THz emission linewidth of a free running continuous wave THz DFG QCL.", "author_names": [ "Seungyong Jung", "Yifan Jiang", "Jae Hyun Kim", "Luigi Consolino", "Saverio Bartalini", "Paolo De", "", "Miriam Serena Vitiello", "Kazuue Fujita", "Masahiro Hitaka", "Akio Ito", "J D Kirch", "Frederic Demmerle", "Gerhard Boehm", "Markus-Christian Amann", "Ayman Mikhail" ], "corpus_id": 165160663, "doc_id": "165160663", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Narrow linewidth ultrabroadband terahertz sources based on difference frequency generation in mid infrared quantum cascade lasers", "venue": "", "year": 2017 }, { "abstract": "We report 5 THz quantum cascade laser sources based on intra cavity difference frequency generation in dual wavelength mid infrared quantum cascade lasers. Our devices produce microwatt level terahertz output at 80 K and approximately 200 nW output at 250 K.", "author_names": [ "Mikhail A Belkin", "Federico Capasso", "Feng Xie", "Alexey Belyanin", "Milan Fischer", "Andreas Wittmann", "Jerome Faist" ], "corpus_id": 2369957, "doc_id": "2369957", "n_citations": 14, "n_key_citations": 3, "score": 0, "title": "Microwatt level terahertz sources based on intra cavity difference frequency generation in mid infrared quantum cascade lasers", "venue": "2008 Conference on Lasers and Electro Optics and 2008 Conference on Quantum Electronics and Laser Science", "year": 2008 } ]

[ { "abstract": "NASDA (National Space Development Agency of Japan) have developed (OICETS (Optical Inter Orbit Communications Engineering Test Satellite) since 1993 in order to get the acquisition, tracking and pointing technology for optical inter satellite communications through the in orbit experiment with ARTEMIS (Advanced Relay and TEchnology Mission Satellite) of European Space Agency. The engineering model of the optical terminal called LUCE (Laser Utilizing Communications Equipment) was tested and its optical performance was evaluated during the thermal vacuum test. The on axis intensity transmitted from the terminal was about 560 MW/Sr with 90 mW of the averaged semiconductor laser output. The full width of the far field pattern of the emitted beam at the point of 1/e2 was about 9.4 (mu) radian.", "author_names": [ "Keizo Nakagawa", "Akio Yamamoto", "Masahiro Toyoda" ], "corpus_id": 108441070, "doc_id": "108441070", "n_citations": 13, "n_key_citations": 0, "score": 1, "title": "Performance test result of LUCE (laser utilizing communications equipment) engineering model", "venue": "LASE", "year": 2000 }, { "abstract": "For the purpose of providing a larger space for designing scaffold and replacing the current method of bone injury repair and bone transplantation by using CAD design with PCL HA as the material of the porous circular structure that can meet the requirements of the mechanical strength of the material. The CT 3D reconstruction model of the hydroxyapatite scaffold was designed and constructed. CT laser scanning was used to study the structure of the femur and lumbar spine with eight male rabbits, using HA PCL as material and using 3D printing technology to make bone tissue engineering scaffold. The blank form of the scaffold, the diameter and porosity of the fiber scaffold, and the loading force, the maximum load and the deformation value of the mechanical data were measured. The resulted showed that the pore connectivity rate of each scaffold in each group was 100% there was no significant difference between the total parameters of the stent and the micro structure parameters. When the load is 320N, the three different cylindrical stents under the maximum pressure, the loading force, deformation and deformation of no significant difference. The result of the present work implied that the combination of CT and CAD reverse technology can complete the design and manufacture of complex bone tissue engineering scaffold materials, there was no significant difference in the physical properties of the porous scaffolds with different loads.", "author_names": [ "Shigang Wang", "Yuhang Fan", "Shufeng Jiang" ], "corpus_id": 55493355, "doc_id": "55493355", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "3D Printing PCL HA Bone Tissue Engineering Scaffold and Its Performance Test", "venue": "", "year": 2016 }, { "abstract": "The Atmospheric Processing Module (APM) is a Mars In Situ Resource Utilization (ISRU) technology designed to demonstrate conversion of the Martian atmosphere into methane for use as rocket propellant for an ascent vehicle. The Martian atmosphere mainly consists of 95% carbon dioxide (CO2) and residual argon and nitrogen. APM utilized cryocoolers for CO2 acquisition from a simulated Martian atmosphere and pressure. The captured CO2 was sublimated and pressurized as a feedstock into the Sabatier reactor, which converted CO2 and hydrogen to methane and water. The Sabatier reaction occurred over a packed bed reactor filled with Ru/Al2O3 catalyst pellets. During performance testing at high flow rates, failure of the Sabatier catalyst occurred, which was detected by unwanted byproducts at elevated reaction temperatures. A Sabatier catalyst failure study was initiated after this event. This led to an effort to develop a model that could determine acceptable flow rates and predict the temperature profile in order to avoid catalyst damage and identify system tolerances. Validation of a computational model with experimental results also aids in long duration system development for reactor scaling purposes. This paper discusses the experimental results of the APM Sabatier tests, as well as a small scale Sabatier reactor that was set up for further model validation. The thermal and kinetic modeling approaches are discussed, as well as results of the APM catalyst characterization which included x ray powder diffraction and x ray photoelectron spectroscopy.", "author_names": [ "Anne J Meier", "Malay G Shah", "Paul E Hintze", "Elspeth M Petersen", "Anthony C Muscatello" ], "corpus_id": 5639135, "doc_id": "5639135", "n_citations": 8, "n_key_citations": 1, "score": 0, "title": "Mars Atmospheric Conversion to Methane and Water: An Engineering Model of the Sabatier Reactor with Characterization of Ru/Al2O3 for Long Duration Use on Mars", "venue": "", "year": 2017 }, { "abstract": "In order to estimate and demonstrate the performance of Thermal And Near infrared Sensor for carbon Observation Fourier Transform Spectrometer (TANSO FTS) and Cloud and Aerosol Imager (TANSO CAI) under the environmental condition on orbit, the Engineering Model (EM) for TANSO FTS and CAI have been developed and demonstrated. The TANSO FTS has three narrow bands detectable regions; 0.76, 1.6 and 2micrion (Band1, 2 and 3) with /2.5cm maximum optical path difference, and a wide band (5.5 14.3micron in thermal near infrared region. The TANSO CAI is a radiometer of ultraviolet (UV) visible, and SWIR, which has 4 spectral band regions with 1 dimensional array CCDs. The initial performance tests have been carried out in the laboratory and the thermal vacuum chamber. The Signal to Noise Ratio (SNR) the polarization sensitivity (PS) Instantaneous Field Of View (IFOV) and response for FTS and CAI, and also the Instrumental Line Shape Function (ILSF) for FTS have been characterized in this test by introducing the light emitted from the black body, halogen lamp and the tunable diode laser. As a results of these experiments, it is appeared that the some modification of system for manufacturing the proto flight model (PFM) is required, and now in progressing. In addition to these characterizations, the newly developed tests, such as the stray light measurement and micro vibration test, are applied on TANSO FTS to estimate the effect on orbit. These tests methods and results are presented in this paper.", "author_names": [ "Hiroshi Suto", "Takahiro Kawashima", "Kei Shiomi", "Tomoko Kina", "Akihiko Kuze", "Tomoyuki Urabe", "Shuji Kawakami", "Yutaka Kaneko", "Takashi Hamazaki" ], "corpus_id": 122209416, "doc_id": "122209416", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "The performance test results for engineering model (EM) of thermal and near infrared sensor for carbon observation (TANSO) on GOSAT", "venue": "SPIE Optical Engineering Applications", "year": 2007 }, { "abstract": "Rock bolt is a support system extensively utilized in Civil and Mining Engineering applications, especially for underground excavations projects. The main function of a rock bolt is to stabilize the rock mass around the opening of an excavation by fastening to further stable formations. Previous technical work developed pull out testing in order to improve understanding regarding the mechanical response within this system. However, due to limitations with conventional laboratory methods of capturing strain, there still exists a lack of understanding in this mechanical response at the micro scale; more specifically, in the detailed strain profile distribution along fully grouted rock bolts. Aiming to address this knowledge gap, two research programmes were conducted and will be addressed in this paper: numerical modelling of pull out tests through finite element method (FEM) and hybrid finite discrete element method (FDEM) and laboratory pull out tests on concrete samples utilizing a newly developed distributed optical strain sensing technology that provides a spatial resolution of 0.65 mm in order to capture the strain along the rock bolt. Experimental and modelling results were compared to evaluate the numerical approaches feasibility and their correspondence with the experiments. FDEM modelling demonstrated ability in capturing general mechanical behavior, while the FEM software seems to be a good option to be utilized as a design tool, yet improvements to the interaction model are necessary to achieve a better calibration with experimental results.", "author_names": [ "Nicholas Vlachopoulos", "Daniel Cruz", "Bryan S A Tatone", "Andrea Lisjak", "O K Mahabadi", "Bradley Forbes", "Carla Carrapatoso" ], "corpus_id": 204786529, "doc_id": "204786529", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "The Performance of Axially Loaded, Fully Grouted Rock Bolts Based on Pull Out Experiments Utilizing Fiber Optics Technology and Associated Numerical Modelling of Such Support Elements", "venue": "Geotechnical and Geological Engineering", "year": 2019 }, { "abstract": "Abstract Laser marking is one of the effective and efficient ways of permanent marking process in the different engineering materials like composites, ceramics and any other hard metals and alloys. The present investigation deals with the experimental analysis on laser marking process using diode pumped Nd:YAG laser considering several process parameters for example lamp current, pulse repetition rate and laser scanning speed. The Response Surface Methodology (RSM) based experimental design was adopted to study in depth the influence of these parameters on marking performance criteria such as mark width, mark depth and mark intensity. Based on experimental results, the second order mathematical models were established. Multi performance optimized parametric combination was achieved to obtain high quality marking using developed models and desirability functions. Moreover, in order to determine the most influencing parameter on the responses, Sensitivity Analysis (SA) was performed on the test results obtained from experimentation as well as predictive models. SEM and optical microscopic images were also analyzed to examine the quality aspects of laser marking on gallium nitride.", "author_names": [ "Ishwer Shivakoti", "Golam Mohammad Kibria", "Bal Bahadur Pradhan" ], "corpus_id": 126726037, "doc_id": "126726037", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Predictive model and parametric analysis of laser marking process on gallium nitride material using diode pumped Nd:YAG laser", "venue": "Optics Laser Technology", "year": 2019 }, { "abstract": "Atomic Clock Ensemble in Space (ACES) is a European Space Agency (ESA) project to be deployed externally to the Columbus Laboratory on the International Space Station (ISS) Two high performance atomic clocks on board ACES generate a frequency reference with stability and accuracy at the 1x10 16 level. The performance of the ACES clock signal results from the combination of the good short term stability of an active hydrogen maser (SHM) and the long term stability and accuracy of a primary standard based on samples of laser cooled Cs atoms (PHARAO) The two clocks are controlled by two servo loops, the first stabilizing the PHARAO local oscillator on SHM clock signal, the second correcting the long term instabilities of SHM using the error signal generated by the PHARAO Cs resonator. This frequency reference, distributed to the ground by a link in the microwave domain is used to perform comparisons of distant clocks and to test Einstein's theory of general relativity. ACES main instrument and subsystems have now reached a high technology readiness level, demonstrated by the completion and the successful test of their engineering models. In particular, a dedicated test campaign has recently verified the performance of the ACES system, where PHARAO and SHM, locked together via the ACES servo loops, are operated as a unique oscillator to generate the ACES frequency reference. The test campaign conducted at CNES premises in Toulouse between July and November 2009 has concluded the engineering models phase, releasing the manufacturing of the ACES flight models. The setup of the ACES system test campaign, the specific tests performed, and the achieved results will be presented and discussed.", "author_names": [ "B Leger", "Luca Stringhetti", "Didier Massonnet", "Ch Delaroche", "F Picard", "M P Hess", "L Cacciapuoti", "S J Feltham", "Rudolph Much", "Rosario Nasca", "T Vudali", "Christophe Salomon", "Ph M Laurent" ], "corpus_id": 11150108, "doc_id": "11150108", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Results of the ACES engineering model system test", "venue": "EFTF 2010 24th European Frequency and Time Forum", "year": 2010 }, { "abstract": "Test model plays an important role in specification testing processes and improves test efficiency. At present test model performance is too simple, relatively few types of performance indicators, this paper presents the test model WTMS which based on user behavior. Besides user loader, response time, CPU utilization rate, WTMS increase the success rate of requests, the actual request time, the best of concurrent users and the maximum number of concurrent user. And performance testing of the subjects are divided into user behavior factors, business factors, the software elements, hardware elements, and test strategy factors. Base on educational administration management system, results show that WTMS model improves test efficiency and accuracy of test results.", "author_names": [ "Deng Lu-juan", "Fan Naimei", "Su Yikun", "Pan Kaijie", "Chen Pei" ], "corpus_id": 63995088, "doc_id": "63995088", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Research on performance test model of Web application", "venue": "", "year": 2013 }, { "abstract": "This paper presents a universal engineering model, which can be used to formulate both counterflow and crossflow cooling towers. By using fundamental laws of mass and energy balance, the effectiveness of heat exchange is approximated by a second order polynomial equation. Gauss Newton and Levenberg Marquardt methods are then used to determine the coefficients from manufactures data. Compared with the existing models, the new model has two main advantages: (1) As the engineering model is derived from engineering perspective, it involves fewer input variables and has better description of the cooling tower operation; (2) There is no iterative computation required, this feature is very important for online optimization of cooling tower performance. Although the model is simple, the results are very accurate. Application examples are given to compare the proposed model with commonly used models. NOMENCLATURE Cpw: specific heat of water under constant pressure; Cs: derivative of saturated ha with respect to Tw; c0 c5: curve fitting constants; dk: search direction of optimization method; Fdata: computation value of ea; ha: enthalpy of air; hs,w: saturation air enthalpy at Tw; hs,wb: saturation air enthalpy at Twb; J(uk) Jacobian matrix of uk; ma: mass flow rate of air; me: mass flow rate of evaporation; ma: mass flow rate of air; mm: mass flow rate of makeup water; mw: mass flow rate of water; NTU: number of transfer units; m: ratio of air to water effective capacitance rate; Qe: heat evaporation rate of loss water; Qrej: heat rejection rate of cooling tower; Tdb: dry bulb temperature of air; Tm: temperature of makeup water; Tw: temperature of water; Twb: wet bulb temperature of air; uk: the value of c0 c5 of the kth iteration; ea: heat transfer effectiveness of Braun's model; h: enthalpy difference with respect to T; T: approach of cooling tower; lk: control coefficients; Subscript i: inlet; o: outlet; INTRODUCTION Cooling towers are commonly used to dissipate heat from heat sources to heat sink (ambient environment) Their applications are typically in Heating Ventilation and Air Conditioning (HVAC) systems and power generators, etc. Heat rejection of cooling towers is accomplished by heat and mass transfer between hot water droplets and ambient air. Although cooling towers are relatively inexpensive and normally consume around ten percent of the whole system energy, their operation has significant effect to the energy consumption of other related subsystems (RMIRA 1995; Michel 1995) Therefore, optimizing cooling tower performance will not only increase the tower efficiencies but also has direct effect to other subsystems. As such, there has been some research interest in this area. Austin (1997) recommended regression methods to create the models of each component in air conditioning systems for predicting and optimizing the system performance. Flake (1997) utilized a different regression technique to determine parameters of the cooling tower model developed by Braun (1989) and to build a predictive model for optimal supervisory control strategies. However, due to the lacking of an effective and precise model for cooling towers, which is essential to estimate and verify the energy savings by different optimization strategies, the research on optimization of cooling tower performance is still in the primary stage. Attempts to develop the cooling tower models have a relative long history, the first such work may trace back to 1925, when Merkel developed a practical model for cooling tower operation, which has been the basis for most modern cooling tower analyses. In his model, the water loss of evaporation is neglected and the Lewis number is assumed to be one in order to simplify the analysis. However, as evaporate water cannot be neglected in cooling tower operation, Merkel's model is not accurate enough and not suitable for real applications. A more rigorous analysis of a cooling tower model that relaxed Merkel's restriction was given by Sutherland (1983) In 1989, Braun developed \"effectiveness models\" for cooling towers, which utilized the assumption of a linearized air saturation enthalpy and the modified definition of number of transfer units. The models were useful for both design and system simulation and has been adopted by the simulation software TRNSYS (SEL 2000) However, Braun's model needs iterative computation to obtain the output results and is not suitable for online optimization. Bernier (1994) reviewed the heat and mass transfer process in cooling towers at water droplet level and analyzed an idealized spray type tower in one dimension, which is useful for cooling tower designers, but no much information is provided to plant operators. Soylemez (1999) presented a quick method for estimating the size and performance of forced draft countercurrent cooling towers and experimental results were used to validate the prediction formulation. Unfortunately, this model also need iterative computation and not suitable for online optimization. In this paper, a universal engineering model, which can be used to formulate both counterflow and crossflow cooling towers, is proposed. Extending the methods provided by Merkel and Braun and using fundamental laws of mass and energy balance, the effectiveness of heat exchange is approximated by a second order polynomial equation. Gauss Newton and Levenberg Marquardt methods are then used to determine the coefficients from manufactures data. Compared with the existing models, the new model has two main advantages: (1) As the engineering model is derived from engineering perspective, it involves fewer input variables and has better description of the cooling tower operation; (2) There is no iterative computation required, this feature is very important for online optimization of cooling tower performance. Although the model is simple, the results are very accurate. Application examples are given for both counterflow and crossflow to compare the proposed model with commonly used models. COOLING TOWER MODEL ANALYSIS The mechanism of heat and mass transfer between ambient air and condenser water inside a cooling tower is illustrated in Figure 1. Figure 1. Schematic representation of heat and mass transfer in the cooling tower AIR WATER i a m i a h o a h o a m", "author_names": [ "L Lu" ], "corpus_id": 6743691, "doc_id": "6743691", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "A Universal Engineering Model For Cooling Towers", "venue": "", "year": 2014 }, { "abstract": "The NASA s Evolutionary Xenon Thruster (NEXT) project is developing an advanced ion propulsion system for future NASA missions for solar system exploration. An engineering model (EM) power processing unit (PPU) for the NEXT project was designed and fabricated by L 3 Communications under contract with NASA Glenn Research Center (GRC) This modular PPU is capable of processing up from 0.5 to 7.0 kW of output power for the NEXT ion thruster. Its design includes many significant improvements for better performance over the state of the art PPU. The most significant difference is the beam supply which is comprised of six modules and capable of very efficient operation through a wide voltage range because of innovative features like dual controls, module addressing, and a high current mode. The low voltage power supplies are based on elements of the previously validated NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) PPU. The highly modular construction of the PPU resulted in improved manufacturability, simpler scalability, and lower cost. This paper describes the design of the EM PPU and the results of the bench top performance tests.", "author_names": [ "Luis R Pinero", "M B Hopson", "Philip C Todd", "Brian R Wong" ], "corpus_id": 111291590, "doc_id": "111291590", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Performance of the NEXT Engineering Model Power Processing Unit", "venue": "", "year": 2007 } ]

[ { "abstract": "The potential of bulk black phosphorus, a layered semiconducting material with a direct band gap of ~0.3 eV, for thermoelectric applications has been experimentally studied. The Seebeck Coefficient (S) has been measured in the temperature range from 300 K to 385 K, finding a value of S +335 10 mV/K at room temperature (indicating a naturally occurring p type conductivity) S increases with temperature, as expected for p type semiconductors, which can be attributed to an increase of the charge carrier density. The electrical resistance drops up to a 40% while heating in the studied temperature range. As a consequence, the power factor at 385 K is 2.7 times higher than that at room temperature. This work indicates the prospective use of black phosphorus in thermoelectric applications such as thermal energy scavenging, which typically require devices with high performance at temperatures near room temperature.", "author_names": [ "Eduardo Flores", "Jose Ramon Ares", "Andres Castellanos-Gomez", "Mariam Barawi", "Isabel J Ferrer", "Carlos S'anchez" ], "corpus_id": 118459355, "doc_id": "118459355", "n_citations": 112, "n_key_citations": 0, "score": 1, "title": "Thermoelectric power of bulk black phosphorus", "venue": "", "year": 2014 }, { "abstract": "The electric field effect is a useful means of elucidating intrinsic material properties as well as for designing functional devices. The electric double layer transistor (EDLT) enables the control of carrier density in a wide range, which is recently proved to be an effective tool for the investigation of thermoelectric properties. Here, we report the gate tuning of thermoelectric power in a black phosphorus (BP) single crystal flake with the thickness of 40 nm. Using an EDLT configuration, we successfully control the thermoelectric power (S) and find that the S of ion gated BP reached +510 mV/K at 210 K in the hole depleted state, which is much higher than the reported bulk single crystal value of +340 mV/K at 300 K. We compared this experimental data with the first principles based calculation and found that this enhancement is qualitatively explained by the effective thinning of the conduction channel of the BP flake and nonuniformity of the channel owing to the gate operation in a depletion mode. Our results provide new opportunities for further engineering BP as a thermoelectric material in nanoscale.", "author_names": [ "Yu Saito", "Takahiko Iizuka", "Takashi Koretsune", "Ryotaro Arita", "Sunao Shimizu", "Yoshihiro Iwasa" ], "corpus_id": 31486087, "doc_id": "31486087", "n_citations": 66, "n_key_citations": 0, "score": 0, "title": "Gate Tuned Thermoelectric Power in Black Phosphorus.", "venue": "Nano letters", "year": 2016 }, { "abstract": "Chemical doping of bulk black phosphorus is a well recognized way to reduce surface oxidation and degradation. Here, we report on the fabrication of terahertz frequency detectors consisting of an antenna coupled field effect transistor (FET) with an active channel of Se doped black phosphorus. Our devices show a maximum room temperature hole mobility of 1780 cm2 V 1 s 1 in a SiO2 encapsulated FET. A room temperature responsivity of 3 V W 1 was observed, with a noise equivalent power of 7 nW Hz 1/2 at 3.4 THz, comparable with the state of the art room temperature photodetectors operating in the same frequency range. The inclusion of Se dopants in the growth process of black phosphorus crystals enables the optimization of the transport and optical performances of FETs in the far infrared with a high potential for the development of BP based electro optical devices. We also demonstrate that the flake thickness can be tuned according to the target application. Specifically, thicker flakes >80 nm) are suitable for applications in which high mobility and high speed are essential, thinner flakes <10 nm) are more appropriate for applications requiring high on/off current ratios, while THz photodetection is optimal with flakes 30 40 nm thick, due to the larger carrier density tunability.", "author_names": [ "Leonardo Viti", "Antonio Politano", "Kai Zhang", "Miriam Serena Vitiello" ], "corpus_id": 58545322, "doc_id": "58545322", "n_citations": 29, "n_key_citations": 0, "score": 0, "title": "Thermoelectric terahertz photodetectors based on selenium doped black phosphorus flakes.", "venue": "Nanoscale", "year": 2019 }, { "abstract": "The electronic properties of the layered black phosphorus (black P) and its monolayer counterpart phosphorene are investigated by using the first principles calculations based on the density functional theory (DFT) The room temperature electronic transport coefficients are evaluated within the semi classical Boltzmann theory. The electrical conductivity exhibits anisotropic behavior while the Seebeck coefficient is almost isotropic. At the optimal doping level and room temperature, bulk black P and phosphorene are found to have large thermoelectric power factors of 118.4 and 138.9 \\mu}Wcm 1K 2, respectively. The maximum dimensionless figure of merit (ZT value) of 0.22 can be achieved in bulk black P by appropriate n type doping, primarily limited by the reducible lattice thermal conductivity. For the phosphorene, the ZT value can reach 0.30 conservatively estimated by using the bulk lattice thermal conductivity. Our results suggest that both bulk black P and phosphorene are potentially promising thermoelectric materials.", "author_names": [ "Hongying Lv", "W -J Lu", "Ding-Fu Shao", "Y P Sun" ], "corpus_id": 117832380, "doc_id": "117832380", "n_citations": 39, "n_key_citations": 0, "score": 0, "title": "Large thermoelectric power factors in black phosphorus and phosphorene", "venue": "", "year": 2014 }, { "abstract": "Efficient continuous wave (CW) and passively Q switched Ho<sup>3+/sup>,Pr<sup>3+/sup>:LiLuF ₄ (Ho,Pr:LLF) laser operating at 2.95 <italic>m</italic>m were realized using a 1150 nm Raman fiber laser as the pump source. A CW output power as high as 1.15 W, which we believe to be the highest one ever achieved from Ho <sup>3+/sup> doped bulk laser emission around 3 <italic>m</italic>m, corresponds to an optical to optical conversion efficiency of 14.5% and a slope efficiency of 15.5% respectively. A high quality saturable absorber (SA) based on multilayered black phosphorus (BP) nanosheet film deposited on a CaF₂ substrate was successfully fabricated and employed. Under the absorbed pump power of 7.36 W, the shortest pulse width of 194.3 ns was obtained, which is the shortest among the two dimensional materials as SA around 3 <italic>m</italic>m. The results not only indicated that Ho,Pr:LLF crystal would be a promising mid infrared (MIR) gain medium for obtaining high power output, but verified that the multilayered BP is a promising optical modulator for generating short pulses in MIR spectral range.", "author_names": [ "Hongkun Nie", "Peixiong Zhang", "Baitao Zhang", "Min Xu", "Kejian Yang", "Xiaoli Sun", "Lianhan Zhang", "Yin Hang", "Jingliang He" ], "corpus_id": 35396500, "doc_id": "35396500", "n_citations": 49, "n_key_citations": 0, "score": 0, "title": "Watt Level Continuous Wave and Black Phosphorus Passive Q Switching Operation of Ho3+,Pr 3+:LiLuF4 Bulk Laser at 2.95 mm", "venue": "IEEE Journal of Selected Topics in Quantum Electronics", "year": 2018 }, { "abstract": "In recent years, two dimensional black phosphorus (BP) has seen a surge of research because of its unique optical, electronic, and chemical properties. BP has also received interest as a potential thermoelectric material because of its high Seebeck coefficient and excellent charge mobility, but further development is limited by the high cost and poor scalability of traditional BP synthesis techniques. In this work, high quality BP is synthesized using a low cost method and utilized in a PEDOT:PSS film to create the first ever BP composite thermoelectric material. The thermoelectric properties are found to be greatly enhanced after the BP addition, with the power factor of the film, with 2 wt BP (36.2 mW m 1 K 2) representing a 109% improvement over the pure PEDOT:PSS film (17.3 mW m 1 K 2) A simultaneous increase of mobility and decrease of the carrier concentration is found to occur with the increasing BP wt which allows for both Seebeck coefficient and electrical conductivity to be increased. These results show the potential of this low cost BP for use in energy devices.", "author_names": [ "Travis G Novak", "Ho Sun Shin", "Jungmo Kim", "Kisun Kim", "Ashraful Azam", "Chien Viet Nguyen", "Sun Hwa Park", "Jae Yong Song", "Seokwoo Jeon" ], "corpus_id": 13696643, "doc_id": "13696643", "n_citations": 23, "n_key_citations": 0, "score": 0, "title": "Low Cost Black Phosphorus Nanofillers for Improved Thermoelectric Performance in PEDOT:PSS Composite Films.", "venue": "ACS applied materials interfaces", "year": 2018 }, { "abstract": "An elementary and economical approach is demonstrated for achieving bulk nanostructured calcium cobalt oxide (CCO) ceramics with enhanced thermoelectric power factor (PF) of 64.2 x 10 3 W m 1 K 2 at 770 K. Nanostructures of CCO are realized by high energy ball milling of the as synthesized CCO and are consolidated using hot press (HP) technique to form fully dense pellets. The morphological, crystallographic, and spectroscopic properties suggest the formation of highly pure nanostructures and ceramics of CCO. The significant improvement of ~11 times in PF for bulk nanostructured CCO ceramics compared to the pellets of as synthesized CCO microstructures is attributed to the enhancement of Seebeck coefficient (S) triggered due to structural deformations originated from the rearrangement of atomic contents and development of oxygen vacancies during the HP process of ceramic formation with application of high pressure at elevated temperatures and introduction of an enlarged interface area at grain boundaries", "author_names": [ "Nidhi Puri", "R P Tandon", "Ajit Kumar Mahapatro" ], "corpus_id": 105756395, "doc_id": "105756395", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Significant Enhancement in Thermoelectric Power Factor of Bulk Nanostructured Calcium Cobalt Oxide Ceramics", "venue": "", "year": 2019 }, { "abstract": "Recent progress in the currently available methods of producing black phosphorus bulk and phosphorene are presented. The effective passivation approaches toward improving the air stability of phosphorene are also discussed. Furthermore, the research efforts on the phosphorene and phosphorene based materials for potential applications in lithium ion batteries, sodium ion batteries, and thermoelectric devices are summarized and highlighted. Finally, the outlook including challenges and opportunities in these research fields are discussed.", "author_names": [ "Yu Zhang", "Yun Zheng", "Kun Rui", "Huey Hoon Hng", "Kedar Hippalgaonkar", "Jianwei Xu", "Wenping Sun", "Jixin Zhu", "Qingyu Yan", "Wei Huang" ], "corpus_id": 21617057, "doc_id": "21617057", "n_citations": 106, "n_key_citations": 0, "score": 0, "title": "2D Black Phosphorus for Energy Storage and Thermoelectric Applications.", "venue": "Small", "year": 2017 }, { "abstract": "We investigate anisotropic electronic structure and thermal transport properties of bulk black phosphorus (BP) Using density functional dynamical mean field theory we first derive a correlation induced electronic reconstruction, showing band selective Kondoesque physics in this elemental $p$ band material. The resulting correlated picture is expected to shed light onto the temperature and doping dependent evolution of resistivity, Seebeck coefficient, and thermal conductivity, as seen in experiments on bulk single crystal BP. Therein, large anisotropic particle hole excitations are key to consistently understand thermoelectric transport responses of pure and doped BP.", "author_names": [ "Luis Craco", "T A S Pereira", "Stefano Leoni" ], "corpus_id": 4997620, "doc_id": "4997620", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Electronic structure and thermoelectric transport of black phosphorus", "venue": "", "year": 2017 }, { "abstract": "Black phosphorus (BP) has attracted great attention for applications in thermoelectric devices, owing to its unique in plane anisotropic electrical and thermal properties. However, its limited conversion efficiency hinders practical application. Here, the thermoelectric properties of 1D BP nanotubes (BPNTs) with different tube chirality are investigated using first principles calculations and Boltzmann transport theory. The results reveal that variation of crystallographic orientation has a distinct impact on band dispersions, which provides a wide tunability of electronic transport. It is shown that (1,1) oriented BPNT structure can yield an order of magnitude enhanced thermoelectric figure of merit ZT at room temperature (as high as 1.0) compared with the bulk counterpart. The distinct enhancement is attributed to the favorable multiple band structures that lead to high carrier mobility of 2430 cm2 V 1 s 1 Further performance improvement can be realized by suitable doping, such as N alloying, reaching an increase of room temperature ZT by a factor of 3 over that of pristine BPNT. The work provides an applicable method to achieve band engineering design, and presents a new strategy of designing 1D BPNT that are promising candidates for flexible, eco friendly, and high performance thermoelectrics.", "author_names": [ "Xin-Yu Chen", "Shuai Duan", "Wencai Yi", "David J Singh", "J G Guo", "Xiaobing Liu" ], "corpus_id": 219587847, "doc_id": "219587847", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Enhanced Thermoelectric Performance in Black Phosphorus Nanotubes by Band Modulation through Tailoring Nanotube Chirality.", "venue": "Small", "year": 2020 } ]

[ { "abstract": "An exciton is the particle like entity that forms when an electron is bound to a positively charged 'hole' An ordered electronic state in which excitons condense into a single quantum state was proposed as a theoretical possibility many years ago. We review recent studies of semiconductor bilayer systems that provide clear evidence for this phenomenon and explain why exciton condensation in the quantum Hall regime, where these experiments were performed, is as likely to occur in electron electron bilayers as in electron hole bilayers. In current quantum Hall excitonic condensates, disorder induces mobile vortices that flow in response to a supercurrent and limit the extremely large bilayer counterflow conductivity.", "author_names": [ "James Philip Eisenstein", "Allan H MacDonald" ], "corpus_id": 1538354, "doc_id": "1538354", "n_citations": 423, "n_key_citations": 2, "score": 1, "title": "Bose Einstein condensation of excitons in bilayer electron systems", "venue": "Nature", "year": 2004 }, { "abstract": "", "author_names": [ "James Philip Eisenstein", "Allan H MacDonald" ], "corpus_id": 197218868, "doc_id": "197218868", "n_citations": 44, "n_key_citations": 0, "score": 0, "title": "Bose Einstein Condensation of Excitons in Bilayer Electron Systems", "venue": "", "year": 2005 }, { "abstract": "Bilayer electron hole systems, where carriers in one layer are electrons and carriers in the other are holes, have been actively investigated in recent years with the focus on Bose Einstein condensation of excitons. This condensation is expected to occur when the layer separation $d$ is much smaller than the interparticle distance {r}_{s}{a}_{B} within each layer. In this Brief Report, we argue for the existence of a state, Wigner supersolid, in which excitons are phase coherent but form a Wigner crystal due to dipolar repulsion. We present the qualitative phase diagram of a bilayer system and discuss properties and possible signatures of the Wigner supersolid phase.", "author_names": [ "Yogesh N Joglekar", "Alexander V Balatsky", "Sankar Das Sarma" ], "corpus_id": 118914084, "doc_id": "118914084", "n_citations": 29, "n_key_citations": 0, "score": 0, "title": "Wigner supersolid of excitons in electron hole bilayers", "venue": "", "year": 2006 }, { "abstract": "We report on small cluster exact diagonalization calculations which prove the formation of electron hole pairs (excitons) as prerequisite for spontaneous interlayer phase coherence in bilayer systems described by the extended Falicov Kimball model. Evaluating the anomalous Green's function and momentum distribution function of the pairs, and thereby analyzing the dependence of the exciton binding energy, condensation amplitude, and coherence length on the Coulomb interaction strength, we demonstrate a crossover between a BCS like electron hole pairing transition and a Bose Einstein condensation of tightly bound preformed excitons. We furthermore show that a mass imbalance between electrons and holes tends to suppress the condensation of excitons.", "author_names": [ "Tatsuya Kaneko", "Satoshi Ejima", "Holger Fehske", "Yukinori Ohta" ], "corpus_id": 119210850, "doc_id": "119210850", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "Exact diagonalization study of exciton condensation in electron bilayers", "venue": "", "year": 2013 }, { "abstract": "At a total filling factor of one two closely spaced two dimensional electron systems (2DES) can be viewed as a Bose Einstein condensate of excitons, where electrons from one 2DES couple to vacant states from the other 2DES. The pairing of electrons and holes (i.e. excitons) is mediated by Coulomb interactions. In this thesis this excitonic state was investigated by interlayer tunneling and Coulomb drag experiments. The Coulomb drag experiments on Corbino ring structures have shown a minimum in the conductivity, implying an energy gap at the Fermi energy due to exciton condensation. The tunneling experiments revealed a critical behavior and an I/V curve reminiscent of the Josephson effect of superconductivity.", "author_names": [ "Lars Tiemann" ], "corpus_id": 124765602, "doc_id": "124765602", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Phase coherence in the regime of bilayer exciton condensation", "venue": "", "year": 2008 }, { "abstract": "Macroscopic quantum states such as superconductors, Bose Einstein condensates and superfluids are some of the most unusual states in nature. In this project, we proposed to design a semiconductor system with a 2D layer of electrons separated from a 2D layer of holes by a narrow (but high) barrier. Under certain conditions, the electrons would pair with the nearby holes and form excitons. At low temperature, these excitons could condense to a macroscopic quantum state either through a Bose Einstein condensation (for weak exciton interactions) or a BCS transition to a superconductor (for strong exciton interactions) While the theoretical predictions have been around since the 1960's, experimental realization of electron hole bilayer systems has been extremely difficult due to technical challenges. We identified four characteristics that if successfully incorporated into a device would give the best chances for excitonic condensation to be observed. These characteristics are closely spaced layers, low disorder, low density, and independent contacts to allow transport measurements. We demonstrated each of these characteristics separately, and then incorporated all of them into a single electron hole bilayer device. The key to the sample design is using undoped GaAs/AlGaAs heterostructures processed in a field effect transistor geometry. In such samples, the density of singlemore 2D layers of electrons could be varied from an extremely low value of 2 x 10{sup 9} cm{sup 2} to high values of 3 x 10{sup 11} cm{sup 2} The extreme low values of density that we achieved in single layer 2D electrons allowed us to make important contributions to the problem of the metal insulator transition in two dimensions, while at the same time provided a critical base for understanding low density 2D systems to be used in the electron hole bilayer experiments. In this report, we describe the processing advances to fabricate single and double layer undoped samples, the low density results on single layers, and evidence for gateable undoped bilayers. less", "author_names": [ "Sungkwun Kenneth Lyo", "Roberto G Dunn", "Michael P Lilly", "D R Tibbetts-Russell", "Larry L Stephenson", "J A Seamons", "John Louis Reno", "Edward S Bielejec", "Wes Edmund Baca", "Jerry A Simmons" ], "corpus_id": 124180311, "doc_id": "124180311", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "LDRD final report on engineered superconductivity in electron hole bilayers.", "venue": "", "year": 2005 }, { "abstract": "Abstract The aim of this project is to explore the strongly correlated states, more specifically Bose Einstein condensation of indirectly bound excitons, in bilayer graphene. During this final reporting period, we have continued our work on the extension of the many body calculations to an atomistic model, examined the electron phonon coupling, studied the possibility of finding the same type of condensation in a 3D topological insulator, and started our work on a time dependent theory to understand the behavior of the time dependent many body systems. In this final progress report, we will outline our most important results and draw some final conclusions from our 3 year project.", "author_names": [ "Matthew J Gilbert" ], "corpus_id": 118128628, "doc_id": "118128628", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Progress Report for Grant Number W911NF 09 1 0347 (University of Illinois Urbana)", "venue": "", "year": 2012 }, { "abstract": "The bilayer systems exhibit the Bose Einstein condensation of excitons that emerge due to Coulomb pairing of electrons belonging to one layer with the holes belonging to the other layer. Here we present the microscopic derivation of the dynamic equation for the condensate wave function at a low density of electron hole $e h$ pairs in a strong magnetic field perpendicular to the layers and an electric field directed along the layers. From this equation we obtain the dispersion law for collective excitations of the condensate and calculate the electric charge of the vortex in the exciton condensate. The critical interlayer spacing, the excess of which leads to a collapse of the superfluid state, is estimated. In bilayer systems with curved conducting layers, the effective mass of the $e h$ pair becomes the function of the $e h$ pair coordinates, the regions arise, where the energy of the $e h$ pair is lowered (exciton traps) and lastly $e h$ pairs can gain the polarization in the basal plane. This polarization leads to the appearance of quantized vortices even at zero temperature.", "author_names": [ "A I Bezuglyj", "Sergej I Shevchenko" ], "corpus_id": 119401969, "doc_id": "119401969", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Dynamic equation for quantum hall bilayers with spontaneous interlayer coherence The low density limit", "venue": "", "year": 2007 }, { "abstract": "The Bose Einstein condensation of excitons has a long history with seminal contributions from Leonid V. Keldysh. Despite numerous efforts, however, a compelling experimental evidence is still missing. A brief survey of attempts to realize exciton condensation in different semiconductor systems is given. Specific problems compared with atomic Bose condensation are highlighted. More details are given on coupled quantum wells as a possible candidate in the search for exciton condensation. While here extremely long radiative lifetimes of indirect excitons can be achieved, their strong dipole dipole repulsion leads to a genuine non ideal behavior. Theoretical results from a dynamical T matrix theory are presented which allow to explain blue shift and line broadening under strong excitation which have been seen in recent high density photoluminescence experiments using a lateral trap. 18.1 A short history of exciton condensation My first encounter with exciton physics was not reading one of the famous textbooks like the 'Knox' (Knox, 1963) but trying to understand the 'Excitonic Insulator' from a review written by Halperin and Rice (1968) Soon we realized that this branch of solid state theory was shaped and brought forward by (at that time) Soviet physicists, with cornerstone papers by Keldysh and coworkers (Keldysh and Kopaev, 1964; Keldysh and Kozlov, 1968) The basic idea was to look at a small gap semiconductor whose energy gap could be tuned to values below the exciton binding energy. Then, the ground state must become unstable against formation of excitonic correlations. The theoretical description is very close to the famous BCS (Bardeen Cooper Schrieffer) theory of superconductivity, only that here the attraction between electron and hole is the standard Coulomb force, while in the BCS the dynamical screening by acoustic phonons provides the necessary attraction. More important, however, are two other facts. In the exciton case, anomalous propagators have a simple physical meaning they are the optically driven interband polarization. Therefore, what needs sophisticated experiments using Josephson junctions in superconductors, can be 282 Bose Einstein condensation of excitons by R. Zimmermann easily done in the excitonic case via interband optics. Secondly, outside the excitonic ground state (or condensate) we find excitons as normal bound states, being thermally excited. There is a long standing claim that the intermediate valent compound TmSeTe fits to the original idea of the excitonic insulator (Bucher et al 1991; Wachter, 2005) When driving the band gap through zero by applying hydrostatic pressure, the material exhibits a phase transition with a critical temperature as high as 250K, which is deduced from measuring thermal properties. Further specific experiments would be needed to clarify if excitons are the main players in this game ruling out competitive mechanisms like charge density wave or lattice instability. A new turn came in when the excitonic insulator was identified as a possible phase transition in wide gap semiconductors, too. If optical recombination is slow enough, excited electrons and holes may reach quasi equilibrium (with common temperature, but different chemical potentials) Although more speculative than the small gap case with strict equilibrium, a lot of interesting physics was to be expected. However, the pressing question 'Does it work, even in principle? was always lurking behind this scenario. This feeling of uncertainty was often seen already in the paper titles, as, e.g. 'Possibility of the excitonic phase in insulators' (which was my first scientific publication, Zimmermann, 1970) The story with the excitonic insulator was coming to rest for some time when a new phase transition from dilute exciton gas to the electron hole liquid was shown to dominate the physics in highly excited semiconductors. Again, Leonid V. Keldysh was among the pioneers of this new 'electron hole droplet physics' (Keldysh, 1968) which is mainly electron gas theory extended to two species (electrons and holes) In fact, the ground state energy minimum for multi valley semiconductors (Si or Ge) is rather deep and lies at relatively high densities. Therefore, the excitonic character of the dilute gas around the droplets was of not much importance, and a random phase like approximation for the twocomponent electron hole plasma did rather well. Indeed, at these high densities, strong screening prevents the formation of excitons as bound states (Mott transition) Things were expected to be different for single valley semiconductors (GaAs, CdS) Theoretical work revealed that in this case even the high density side of the first order phase diagram bears excitonic signatures (Zimmermann, 1976) However, these materials have a direct band gap with dipole allowed optical transitions, and the much shorter radiative lifetime prevents the build up of quasi equilibrium under high excitation. Still it was general belief that here a quite interesting sequence could be expected with rising density: Formation of excitons, their Bose Einstein condensation (BEC) strong nonideal effects due to the underlying fermionic structure (excitonic insulator) and a high density plasma which looses the excitonic correlations gradually (Zimmermann, 1988) When including polar optical phonons into the electron hole plasma theory, Leonid V. Keldysh was once more paving the way (Keldysh and Silin, 1975) which gave me the first chance to come into personal contact with him, and to A short history of exciton condensation 283 learn quite a lot (which continued to be the case at all further meetings) How to overcome the exciton lifetime problem? One way was to use wide gap semiconductors with dipole forbidden optical transitions. The paradigm material is here cuprous oxide which has indeed a long history on the search for exciton BEC. Following earlier claims on biexciton condensation in CuCl (Nagasawa et al 1975) pioneering work on Cu2O was done by Wolfe (Lin and Wolfe, 1993) and Mysyrowicz (Mysyrowicz et al 1996) However, several findings were not really conclusive, for instance to read off directly the bosonic distribution function from the (phonon assisted) photoluminescence. Other BEC claims found a different and much less spectacular explanation, as, e.g. exciton super transport being driven by phonon wind (Bulatov and Tikhodeev, 1992; Tikhodeev, 1997) Quite recently, new findings on Cu2O give new hopes, as the exploration of 1s 2p transitions using infrared femtosecond spectroscopy (Kuwata Gonokami, 2005) Another way to achieve extremely long radiative lifetimes of excitons is using coupled quantum wells. Application of a static electric field in the growth direction allows to tilt the confinement potentials such that the lowest state has electrons and holes residing in different quantum wells. A spatially indirect exciton is formed which acquires microsecond lifetime since the overlap between electron and hole is exponentially small. Already in 1976, Lozovik made a first theoretical prediction for the excitonic insulator in such a system (Lozovik and Yudson, 1976) The first experimental hint on a possible BEC was reported quite early, too (Fuzukawa et al 1990) But here again, spectacular findings as the nearly millimeter sized ring emission has been considered first as BEC evidence (Butov, 2002; Snoke et al 2002) but are now discussed in terms of a dynamic p n junction. Still, the quite regular fragmentation of this ring emission is waiting for a conclusive explanation. Another interesting issue is to take the fluctuations (noise) of the photoluminescence as indicator of BEC (Butov, 2003) In Sections 18.3 and 18.4 we give more details and own theoretical results for this very promising system, focussing on the emission lineshape. It is quite common knowledge that at a given density, the BEC critical temperature is larger if the Bose particles have a lighter mass (a specific example is given in eqn (18.3) below) Usually, the exciton mass is dictated by the underlying semiconductor material. However, if exciton polaritons are formed within a microcavity, the dispersion is dominated by the cavity mode, and the relevant polariton mass can be orders of magnitude smaller than the exciton mass. However, there is always a price to be paid! Here, the system has to be pumped hard in order to get reasonable polariton densities. Furthermore, the cooling is slowed down since only the exciton part in the polariton is able to transfer energy to the lattice (Doan et al 2005) Both effects hinder to establish quasi equilibrium, which we consider to be one condition for classification as BEC. At least bosonic stimulation has been seen (Deng et al 2003) and interesting features like parametric scattering under resonant pumping have been reported, too (Baumberg et al 2000) For the latter, a description as 'driven condensate' would be probably right. In a genuine BEC, we hope to see a condensate whose phase coherence 284 Bose Einstein condensation of excitons by R. Zimmermann Table 18.1. Bose Einstein condensation of excitons is rather improbable if not impossible since: Excitons are: due to: While for atoms, instable radiative decay stability is given hard to equilibrate slow cooling sophisticated within lifetime cooling in use composite bosons electron hole pairs, electron ion Mott transition! plasma is far away strongly non ideal dipolar repulsion repulsion is weak (hinders condensation) builds up spontaneously, and is not triggered from outside. A more exotic version of exciton condensation is discussed for the quantum Hall effect in electron bilayer systems. At half filling, a description in terms of electrons and holes within the Landau level can be applied. Using the exciton terminology provides a new look on this system (Eisenstein and MacDonald, 2004) but it may be que", "author_names": [ "R Zimmermann" ], "corpus_id": 10804925, "doc_id": "10804925", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "BOSE EINSTEIN CONDENSATION OF EXCITONS: PROMISE AND DISAPPOINTMENT", "venue": "", "year": 2008 }, { "abstract": "The bosonic atoms used in present day experiments on Bose Einstein condensation are made up of fermionic electrons and nucleons. In this Letter we demonstrate how the Pauli exclusion principle for these constituents puts an upper limit on the Bose Einstein condensed fraction. Detailed numerical results are presented for hydrogen atoms in a cubic volume and for excitons in semiconductors and semiconductor bilayer systems. The resulting condensate depletion scales differently from what one expects for bosons with a repulsive hard core interaction. At high densities, Pauli exclusion results in significantly more condensate depletion. These results also shed a new light on the low condensed fraction in liquid helium II.", "author_names": [ "Stefan M A Rombouts", "", "Kris Van Houcke" ], "corpus_id": 119477787, "doc_id": "119477787", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Consequences of the Pauli exclusion principle for the Bose Einstein condensation of atoms and excitons", "venue": "", "year": 2005 } ]

[ { "abstract": "Assembly and reliability of lead free solder joints are very important topics in electronic manufacturing. There are many books [1 69] and papers [70 315] written on them. In this book, the assembly of lead free solder joints such as prevailing lead free materials, soldering processes, advanced specialty flux design, and characterization of lead free solder joints will be discussed, respectively in Chaps. 2 5. The reliability of lead free solder joints such as reliability testing and data analyses, design for reliability, and failure analyses of lead free solder joints will be discussed, respectively in Chaps. 6 8. The special features of this book are the materials covered are not only for electronic manufacturing services (EMS) on the second level interconnects, but also for packaging assembly on the first level interconnects and for the semiconductor back end on the 2.5D and 3D IC integration interconnects as shown in Fig. 1.1. The solder joints in various plated through hole (PTH) and surface mount technology (SMT) printed circuit board (PCB) assemblies, and semiconductor packages will be discussed in this chapter.", "author_names": [ "John H Lau", "Ning-Cheng Lee" ], "corpus_id": 219879245, "doc_id": "219879245", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Solder Joints in PCB Assembly and Semiconductor Packaging", "venue": "", "year": 2020 }, { "abstract": "In high reliability Surface Mount Technology (SMT) assembly applications, the ability to inspect the solder joints visually has been standard and has been key factors in providing confidence in solder joint reliability. Inspection techniques such as X ray can be used to detect gross manufacturing defects such as solder bridging, but are not suitable for detection of other defects such as cracks. Temperature cycling test (TCT) is a standard solder joint reliability assessment method in semiconductor reliability for ball grid array (BGA) packaging. SMT reflow process and CTE (coefficient of thermal expansion) between solder materials, PCB and BGA package have high influence in solder joint reliability. A careful experimental investigation was undertaken to evaluate the reliability of solder joints of SAC BGA components formed using Sn 2Ag Cu Ni solder paste. This evaluation specifically looked at the impact of time above liquidus, peak temperature and thermal interface material (TIM) on solder joint reliability. Four types of samples prepared with the peak temperature of 2500C and no TIM, 2500C with TIM, time above liquidus (TAL) 90 seconds and no TIM and TAL 90 seconds with TIM. A total of 60 drives were assembled and subjected to accelerated thermal cycling (ATC) test in the temperature range of 00C to 1000C for a maximum of 2000 cycles with reference to JESD22 A104 standard. Based on the results from the deisgn of experiment (DOE) TAL 90s profile have demonstrated better TCT reliability margin compared to peak temperature of 2500C.", "author_names": [ "Mohammad Zainudeen Moideen", "Chong Leong Gan" ], "corpus_id": 47547433, "doc_id": "47547433", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Solder joint reliability enhancement through surface mounting solder joint reflow optimization in enterprise grade solid state drives (SSDs)", "venue": "2016 IEEE 37th International Electronics Manufacturing Technology (IEMT) 18th Electronics Materials and Packaging (EMAP) Conference", "year": 2016 }, { "abstract": "In high reliability Surface Mount Technology (SMT) assembly applications, the ability to inspect the solder joints visually has been standard and has been key factors in providing confidence in solder joint reliability. Inspection techniques such as X ray can be used to detect gross manufacturing defects such as solder bridging, but are not suitable for detection of other defects such as cracks. Temperature cycling test (TCT) is a standard solder joint reliability assessment method in semiconductor reliability for ball grid array (BGA) packaging. SMT reflow process and CTE (coefficient of thermal expansion) between solder materials, PCB and BGA package have high influence in solder joint reliability. A careful experimental investigation was undertaken to evaluate the reliability of solder joints of SAC BGA components formed using Sn 2Ag Cu Ni solder paste. This evaluation specifically looked at the impact of time above liquidus, peak temperature and thermal interface material (TIM) on solder joint reliability. Four types of samples prepared with the peak temperature of 2500C and no TIM, 2500C with TIM, time above liquidus (TAL) 90 seconds and no TIM and TAL 90 seconds with TIM. A total of 60 drives were assembled and subjected to accelerated thermal cycling (ATC) test in the temperature range of 00C to 1000C for a maximum of 2000 cycles with reference to JESD22 A104 standard. Based on the results from the deisgn of experiment (DOE) TAL 90s profile have demonstrated better TCT reliability margin compared to peak temperature of 2500C.", "author_names": [ "Mohammad Zainudeen Moideen", "Chong Leong Gan" ], "corpus_id": 42186138, "doc_id": "42186138", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Solder joint reliability enhancement through surface mounting solder joint reflow optimization in enterprise grade solid state drives (SSDs)", "venue": "2016 IEEE 37th International Electronics Manufacturing Technology (IEMT) 18th Electronics Materials and Packaging (EMAP) Conference", "year": 2016 }, { "abstract": "Fan out wafer level packaging (FOWLP) is one of the latest technologies to meet the requirements of high performance and thin form factor, especially for mobile application processors. To achieve a simple path way and thinner package form, many outsourced semiconductor assembly and test (OSAT) suppliers and foundries provide FOWLP capabilities. Most solutions are limited to the bottom 2D package area with a package on package (PoP) stacking structure to communicate logic to memory or a peripheral chip beyond the 2D distribution area. This means that communication between heterogeneous chips has more power and signal loss by PoP interconnection to reach hetero chip functions through bulk solder ball joints and printed circuit board (PCB) laminated routing with more coarse trace pattern than a fan out (FO) redistribution layer (RDL pattern) To improve this situation, high performance heterogeneous integration has been simulated and successfully realized with the novel 3D Silicon Wafer Integrated Fan out Technology (SWIFT(r) prototype as chip stackable, ultra thin, high flexibility FOWLP for the first ultimate 3D packaging. Also, this has been proven to be a highly flexible and cost effective structure with a low risk process flow, low package warpage, stable electrical performance, and good reliability performance. The form factor of the 3D SWIFT design with various structure options is as much as 45% thinner than PoP technology.", "author_names": [ "WonMyoung Ki", "Wongeol Lee", "In Su Mok", "Ilbok Lee", "WonChul Do", "Mohammed Kolbehdari", "Alex Copia", "Suresh Jayaraman", "Curtis Zwenger", "KangWook Lee" ], "corpus_id": 51981231, "doc_id": "51981231", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Chip Stackable, Ultra thin, High Flexibility 3D FOWLP (3D SWIFT(r) Technology) for Hetero Integrated Advanced 3D WL SiP", "venue": "2018 IEEE 68th Electronic Components and Technology Conference (ECTC)", "year": 2018 }, { "abstract": "Due to environmental concerns, the need for lead free solutions in electronic components and systems is receiving increasing attention within the semiconductor and electronics industries. Sn Ag Cu systems are some of the more promising materials to replace the eutectic Sn Pb solder. In this paper, a chip scale package assembled on board test and a notebook motherboard surface mount assembly were used to investigate the characteristics of Sn 3.0 Ag 0.5 Cu solder alloy from three different companies. One eutectic tin lead solder was included for comparison. For the chip scale package, the PCB's surface finish included OSP (organic solderability preservatives) and electroless Ni/immersion Au. OSP and immersion Ag PCB surface finish was used in the notebook motherboard surface mount assembly. In circuit test and function test were used to evaluate the properties. Thermal cycling test was used to evaluate the reliability of the solder joints. Failure modes of Sn Ag Cu solder and Sn Pb solder alloys were also investigated. Scanning electron microscope (SEM) and optical microscope (OM) were utilized to observe the fracture morphology; energy dispersive spectrometer (EDS) was employed to analyze the distribution of the elements and the intermetallic compounds (IMCs) formed at the interface. All the chip scale package samples passed the electrical test after 2500 thermal cycles. All Sn Pb and Sn Ag Cu solder joints of CSP possess good board level reliability. But the TCT results of notebook motherboard assembled by Sn Ag Cu were not so good. About one half of samples didn't pass the function test after 500 thermal cycles. By failure analyses, we found some cracks in the joints and all the failed components were made by ceramic based chip.", "author_names": [ "Jian-Shu Wu", "Shan-Pu Yu", "I-Hsuan Peng", "Jong-Lih Wang", "B Chung" ], "corpus_id": 136974041, "doc_id": "136974041", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Board level reliability of lead free SnAgCu solder joint", "venue": "Proceedings of the 4th International Symposium on Electronic Materials and Packaging, 2002.", "year": 2002 }, { "abstract": "Technologies are focusing on empowering consumers with more functionalities into compact assemblies such as ball grid array (BGA) and Chip Scale Packaging (CSP) offering small form factors to enable high density semiconductor applications. Reliable performance under drop test conditions is of paramount importance for components targeted for some hand held applications. Drop testing per JESD22 B111, prescribed by the Joint Electronic Device Engineering Council (JEDEC) is an industrial standard to characterize mechanical reliability of solder joints subject to drop impact under the specified test conditions. This specification was recently revised to JESD22 B111A version, with intent to provide homogenous stress distribution for all components mounted on the newly prescribed PCB layout. The objective of this paper is to assess the impact of these test board changes on drop test performance of solder interconnects and failure modes generated. It is carried out by recording the board dynamic response upon drop impact for test boards with three different form factors. It is complemented well with the Finite Element Modelling (FEM) developed for the studied drop test settings. The investigation is supported by targeted experiments on some prominent package styles. The drop test results show increased characteristic lifetime of solder joints when dropped using the square shaped test board defined by JESD22 B111A as compared to the outstanding studied specifications. This observation is linked to the impact of changing drop impact pulse, PCB form factor and build up construction on the board dynamics such as resonance frequency modes and PCB deformation.", "author_names": [ "Varun Thukral", "Jeroen J M Zaal", "R Roucou", "J Jalink", "R T H Rongen" ], "corpus_id": 51975726, "doc_id": "51975726", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Understanding the Impact of PCB Changes in the Latest Published JEDEC Board Level Drop Test Method", "venue": "2018 IEEE 68th Electronic Components and Technology Conference (ECTC)", "year": 2018 }, { "abstract": "Solid state lighting (SSL) which is based 0n semiconductor Lighting Emitting Diode (LED) is the most promising and reliable energy saving solution for future lighting applications. Since a bare LED die can hardly survive without a package, one of the most import function of the LED package is to facilitate the electrical connection and heat dissipation of the light engine mounted on a printed circuit board (PCB) by Land Grid Array (LGA) solder joints. These joints have been proven to be one of the most vulnerable link in the system. Therefore, evaluating the reliability of solder joints becomes vital to ensure the long term reliability of this new lighting product. A combined theoretical and experimental approach based on Finite Element (FE) calculations is a fast and commonly adopted way of estimating the solder reliability in microelectronics industry. However, there is no fatigue model that is particularly suitable for Land Grid Array (LGA) solder joints, which are mostly employed in board level LED packages. Additionally, it would be desirable to have cruder engineering guidelines to quickly estimate the effect of the various geometries and dimensions for new trial LGA configurations. On the other hand, relatively accurate lifetime predictions still required Accelerated Life Tests (ALT) However, current reliability testing methods based on the detection of final catastrophic failure generally require very long test time (up to 9000 hours or 55 weeks) which does not meet the industrial target to limit the testing time to 6 12 weeks. A test method that is capable of carefully separating and in situ monitoring the fatigue damages may be able to resolve the issue by offering the possibility of early termination of the test once enough information is collected to predict final and catastrophic failure. In addition, this capability can be attractive to make more accurate Remaining Useful Lifetime prognostic of solder joint in many critical electronics in other systems. In Chapter 2, it was demonstrated that the widely accepted fatigue model for predicting the lifetime of BGA solder joint no longer valid for assessing reliability of solder joint in a LGA assembly due to its inappropriate critical elements selection method. Therefore, a more suitable critical element selection method for LGA assemblies is proposed based on statistical analysis of creep energy density distribution for elements in the vicinity of the likely crack initiation point. By adopting this new critical element selection method, a new energy based fatigue model for predicting LGA solder life times has been established by combining lifetime measurements with corresponding Finite Element Method (FEM) simulations for different material combinations and different LED package configurations. The model has a much better predictive power than the model based on the BGA approach. In chapter 3, a phenomenological response surface model is derived for a fast qualification of the reliability of LED packages with different designs by conducting a series of FEM simulations. It seems that a smaller carrier size and larger solder standoff height in general will result in better solder reliability. This trend is more pronounced in solder with smaller carrier size and larger stand off height. Additionally, solder reliability decreases rapidly with solder coverage decreasing. The ratio between thermal solder area and electrical solder area AR has a significant influence on solder joint reliability in a SSL system. The optimal AR value is also observed to relate to carrier size and solder coverage. In general, the optimal AR value increases with increasing carrier size, and this phenomenon is more pronounced in packages with smaller solder coverage. When the chip carrier size is relative small, it is advisable to make the thermal pad and electrical pad comparable. The proposed methodology in this work, a combination of energy based fatigue modeling and FEM modeling proves to be very valuable for solder reliability optimization for LED packages. This methodology can also be applied to optimize the package configuration in terms of thermal performance, electrical performance, cost and combinations thereof. The predictive power and the limitations of the approach are also discussed in Chapter 3. The advantages of in situ high precision damage monitor during ALT are demonstrated, which offers great potential to save testing time. In Chapter 4, precise fatigue damage monitoring is proven to be achievable by conducting in situ high precision (apx. 80 n? electrical resistance measurement of each individual solder joint during testing. The method was shown to be capable of capturing viscoplastic deformation accumulation, resulted crack initiation and sequenced crack propagation in an isothermal fatigue test. Moreover, in Chapter 5, it is demonstrated that using dedicated electrode configurations, different types of fatigue damages can be separated from each other or highlighted depending on the testing purpose. The effect of viscoplastic deformation can best be separated from those due to crack formation in one electrode configuration whereby progressive viscoplastic deformation induces resistance decay, whereas crack initiation and propagation provokes resistance increasing. It allows a rather precise yet conservative estimation of the crack initiation point. The other two configurations studied demonstrated superior sensitivity to crack opening and closure during fatigue cycling, which gives saw teeth shaped signal patterns, in which case the measured resistance increases with both progressive viscoplastic deformation and propagating crack. The experimental findings agree with results from FEA simulation and periodic tomographic analyses. However, even for very high resolution of the electrical resistance measurements as in the present work, identification of the very early stages of crack initiation (less than 5% of the joint contact zone) remains not really feasible. In Chapter 6, the knowledge gained for monitoring failure under isothermal conditions is transferred to the testing of solder joints subjected to thermo mechanical loading, employing a different crack initiation identification method. Accelerated temperature cycling test was done to four LED like board level ceramic packages with in situ periodic high precision electrical resistance monitoring for each solder joint inside. Not the actual electrical resistance values but the change in Temperature Coefficient of Resistance (TCRc) of the solder joint was correlated to fatigue damage evolution in the joint. Both viscoplastic deformation accumulation and crack propagation increase the TCR. A method to identify the crack initiation point based on the noise analysis of in situ TCRc monitoring signal of individual solder joint is presented. It is observed that once a major crack is present in the joint the noise level increases significantly, and the rate of TCR increase increases with further crack growth. The crack initiation point as determined from the electrical resistance data using a built in variance analysis tool in Matlab, was verified by micro tomographic results and FEM simulation predictions. The new method as developed can be a very attractive technique for both solder accelerated test and RUL prognostics.", "author_names": [ "Jianshan Zhang" ], "corpus_id": 107999668, "doc_id": "107999668", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Fast Qualification of Solder Reliability in Solid state Lighting System", "venue": "", "year": 2015 }, { "abstract": "The solder joint reliability of semiconductor package interconnects is critical to product durability. A dominant failure mode is solder fatigue due to the CTE mismatch between BGA component and PCB at thermal cycling. It is well known that besides thermal expansion mismatch of component and board, the solder joint geometry has a great impact on fatigue behavior and time to failure. In this study, a combination of Surface Evolver and finite element analysis are use to predict the solder joint shapes for the assembly of medium pin count BGA's and to estimate the reliability at accelerated temperature cycling conditions. Results of Surface Evolver are compared with the assumption of a truncated sphere. The solder shape predictions are applied for a subsequent thermo mechanical analysis of the BGA assembly. Inelastic creep deformation is evaluated for critical solder balls, and the Coffin Manson relation is used to estimate the solder joint lifetime. The entire simulation procedure will be demonstrated for a.", "author_names": [ "Betty Yeung", "Torsten Hauck", "Brett Wilkerson", "T Koschmieder" ], "corpus_id": 138675171, "doc_id": "138675171", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Thermal Cycling Analysis of BGA Solder Joint Reliability", "venue": "", "year": 2012 }, { "abstract": "Trends in the packaging of semiconductors are towards miniaturization and high functionality. The package on package (PoP) with increasing demands is beneficial in cost and space saving. This study conducts the assembly of the PoP component through the stacking process. Samples are subject to thermal cycling test condition, 0degC to 100degC. The failure of samples is defined as when the measured resistance is above 3D. The cross section and dye penetrate analysis are used to investigate the failure modes. Results shows that majority of failure occurred to bottom components. The failure location is at interface between component pad and the solder joint due to the CTE mis match between bottom chip and the PCB. The warpage of PoP substrate has resulted in variation in standoff height across the components. Failure data is verified to follow a Weibull distribution. The parameters of the Weibull distribution are identified. The expected life for the PoP solder joint is determined to be 5600 cycles in the temperature range of 0degC to 100degC.", "author_names": [ "Jimmy Yang", "Jay Cy Huang", "K C Li", "J L Ku", "Andrew Lee" ], "corpus_id": 23704355, "doc_id": "23704355", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Reliability assessment for the PoP lead free solder joint through temperature cycling test", "venue": "2010 5th International Microsystems Packaging Assembly and Circuits Technology Conference", "year": 2010 }, { "abstract": "Recently, handheld electronic products are prone to being dropped during their useful service life because of their size and weight. Board level solder joint reliability performance of IC packages during drop impact becomes a great concern to semiconductor and electronic product manufacturers. The packages are susceptible to solder joint failures, induced by a combination of PCB bending and mechanical shock during impact. Therefore, board level drop testing is an effective method to characterize the solder joint reliability performance of miniature handheld products. In this study, we examine and compare simulation the board level drop test of SSD. Applying the JEDEC (JESD22 B111) standard present a finite element modeling of the BGA package assembly was performed to study the stress and strain behavior of the solder joints during drop test. The simulation revealed that maximum stress was located at the outermost solder ball in the PCB or Package side, which consisted well with the location of crack initiation observed in the failure analysis after drop reliability tests.", "author_names": [ "Tae Min Kang", "Yong Chang Lee", "Byung Kwon Bae", "Won Seob Song", "Jae Sung Lee" ], "corpus_id": 41054293, "doc_id": "41054293", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A study on the correlation between experiment and simulation board level drop test for SSD", "venue": "2017 18th International Conference on Thermal, Mechanical and Multi Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)", "year": 2017 } ]

[ { "abstract": "The Schottky barrier height in metal/Ge contacts shows weak dependence on the metal work function indicating strong Fermi level pinning close to the Bardeen limit. The pinning factor S is about 0.05 and the charge neutrality level (CNL) is only about 0.09eV above the top of the valence band. Because of this, the Fermi level in Ge lies higher than CNL in most cases of interest so that unpassivated acceptorlike gap states at the interface are easily filled, building up a net negative fixed charge. This could prevent efficient inversion of a p type Ge surface in a metal oxide semiconductor structure.", "author_names": [ "Athanasios Dimoulas", "Polychronis Tsipas", "A Sotiropoulos", "Evangelos Evangelou" ], "corpus_id": 121799771, "doc_id": "121799771", "n_citations": 481, "n_key_citations": 6, "score": 1, "title": "Fermi level pinning and charge neutrality level in germanium", "venue": "", "year": 2006 }, { "abstract": "Density functional theory calculations are performed to unravel the nature of the contact between metal electrodes and monolayer MoS2. Schottky barriers are shown to be present for a variety of metals with the work functions spanning over 4.2 6.1 eV. Except for the p type Schottky contact with platinum, the Fermi levels in all of the studied metal MoS2 complexes are situated above the midgap of MoS2. The mechanism of the Fermi level pinning at metal MoS2 contact is shown to be unique for metal 2D semiconductor interfaces, remarkably different from the well known Bardeen pinning effect, metal induced gap states, and defect/disorder induced gap states, which are applicable to traditional metal semiconductor junctions. At metal MoS2 interfaces, the Fermi level is partially pinned as a result of two interface behaviors: first by a metal work function modification by interface dipole formation due to the charge redistribution, and second by the production of gap states mainly of Mo d orbitals character by the weakened intralayer S Mo bonding due to the interface metal S interaction. This finding would provide guidance to develop approaches to form Ohmic contact to MoS2.", "author_names": [ "Cheng Gong", "Luigi Pietro Maria Colombo", "Robert M Wallace", "Kyeongjae Cho" ], "corpus_id": 20629763, "doc_id": "20629763", "n_citations": 449, "n_key_citations": 6, "score": 0, "title": "The unusual mechanism of partial Fermi level pinning at metal MoS2 interfaces.", "venue": "Nano letters", "year": 2014 }, { "abstract": "The purpose of this paper is to understand metal/germanium (Ge) junction characteristics. Electrode metals with a wide work function range were deposited on Ge. All metal/p Ge and metal/n Ge junctions have shown Ohmic and Schottky characteristics, respectively, with the strong Fermi level pinning. The charge neutrality level (CNL) at metal/Ge interface is close to the branch point calculated for the bulk Ge. Moreover, the pinning level is hardly modulated by annealing in forming gas, forming metal germanide/Ge interfaces or changing the substrate orientation. These results suggest that Fermi level at metal/Ge interface is intrinsically pinned at the CNL characterized by the metal induced gap states model.", "author_names": [ "Tomonori Nishimura", "Koji Kita", "Akira Toriumi" ], "corpus_id": 119771153, "doc_id": "119771153", "n_citations": 341, "n_key_citations": 5, "score": 0, "title": "Evidence for strong Fermi level pinning due to metal induced gap states at metal/germanium interface", "venue": "", "year": 2007 }, { "abstract": "Photoelectron spectroscopy has been used to map out energy level alignment of conjugated polymers at various organic organic and hybrid interfaces. Specifically, we have investigated the hole injection interface between the substrate and light emitting polymer. Two different alignment regimes have been observed: (i) Vacuum level alignment, which corresponds to the lack of vacuum level offsets (Schottky Mott limit) and (ii) Fermi level pinning, where the substrate Fermi level and the positive polaronic level of the polymer align. The observation is rationalized in terms of spontaneous charge transfer whenever the substrate Fermi level exceeds the positive polaron/bipolaron formation energy per particle. The charge transfer leads to the formation of an interfacial dipole, as large as 2.1 eV.", "author_names": [ "Carl Tengstedt", "Wojciech Osikowicz", "William Raymond Salaneck", "Ian D Parker", "Che-Hung Hsu", "Mats Fahlman" ], "corpus_id": 122632644, "doc_id": "122632644", "n_citations": 302, "n_key_citations": 4, "score": 0, "title": "Fermi level pinning at conjugated polymer interfaces", "venue": "", "year": 2006 }, { "abstract": "Electrical metal contacts to two dimensional (2D) semiconducting transition metal dichalcogenides (TMDCs) are found to be the key bottleneck to the realization of high device performance due to strong Fermi level pinning and high contact resistances (Rc) Until now, Fermi level pinning of monolayer TMDCs has been reported only theoretically, although that of bulk TMDCs has been reported experimentally. Here, we report the experimental study on Fermi level pinning of monolayer MoS2 and MoTe2 by interpreting the thermionic emission results. We also quantitatively compared our results with the theoretical simulation results of the monolayer structure as well as the experimental results of the bulk structure. We measured the pinning factor S to be 0.11 and 0.07 for monolayer MoS2 and MoTe2, respectively, suggesting a much stronger Fermi level pinning effect, a Schottky barrier height (SBH) lower than that by theoretical prediction, and interestingly similar pinning energy levels between monolayer and bulk MoS2. Our results further imply that metal work functions have very little influence on contact properties of 2D material based devices. Moreover, we found that Rc is exponentially proportional to SBH, and these processing parameters can be controlled sensitively upon chemical doping into the 2D materials. These findings provide a practical guideline for depinning Fermi level at the 2D interfaces so that polarity control of TMDC based semiconductors can be achieved efficiently.", "author_names": [ "Changsik Kim", "Inyong Moon", "Daeyeong Lee", "Min Sup Choi", "Faisal Ahmed", "Seunggeol Nam", "Yeonchoo Cho", "Hyeon-Jin Shin", "Seongjun Park", "Won Jong Yoo" ], "corpus_id": 206706267, "doc_id": "206706267", "n_citations": 297, "n_key_citations": 7, "score": 0, "title": "Fermi Level Pinning at Electrical Metal Contacts of Monolayer Molybdenum Dichalcogenides.", "venue": "ACS nano", "year": 2017 }, { "abstract": "The Schottky barrier for carrier injection into 2D semiconductors can be effectively tuned by using 2D metals. Two dimensional (2D) semiconductors have shown great potential for electronic and optoelectronic applications. However, their development is limited by a large Schottky barrier (SB) at the metal semiconductor junction (MSJ) which is difficult to tune by using conventional metals because of the effect of strong Fermi level pinning (FLP) We show that this problem can be overcome by using 2D metals, which are bounded with 2D semiconductors through van der Waals (vdW) interactions. This success relies on a weak FLP at the vdW MSJ, which is attributed to the suppression of metal induced gap states. Consequently, the SB becomes tunable and can vanish with proper 2D metals (for example, H NbS2) This work not only offers new insights into the fundamental properties of heterojunctions but also uncovers the great potential of 2D metals for device applications.", "author_names": [ "Yuanyue Liu", "Paul Stradins", "Suhuai Wei" ], "corpus_id": 27833640, "doc_id": "27833640", "n_citations": 279, "n_key_citations": 5, "score": 0, "title": "Van der Waals metal semiconductor junction: Weak Fermi level pinning enables effective tuning of Schottky barrier", "venue": "Science Advances", "year": 2016 }, { "abstract": "The passivation of interface states remains an important problem for III V based semiconductor devices. The role of the most stable bound native oxides GaOx (0.5<=x<=1.5) is of particular interest. Using monochromatic x ray photoelectron spectroscopy in conjunction with controlled GaAs(100) and InGaAs(100) surfaces, a stable suboxide (Ga2O) bond is detected at the interface but does not appear to be detrimental to device characteristics. In contrast, the removal of the Ga 3+ oxidation state (Ga2O3) is shown to result in the reduction of frequency dispersion in capacitors and greatly improved performance in III V based devices.", "author_names": [ "Christopher L Hinkle", "M Milojevic", "Barry Brennan", "A M Sonnet", "F S Aguirre-Tostado", "Greg Hughes", "Eric M Vogel", "Robert M Wallace" ], "corpus_id": 53541370, "doc_id": "53541370", "n_citations": 236, "n_key_citations": 5, "score": 0, "title": "Detection of Ga suboxides and their impact on III V passivation and Fermi level pinning", "venue": "", "year": 2009 }, { "abstract": "Due to the strong Fermi level pinning close to the germanium (Ge) valence band edge, all metal/p type Ge contacts show Ohmic characteristics, while metal/n type Ge contacts exhibit rectifying behaviors. In this paper, we report a simple method to alleviate this Fermi level pinning effect by inserting a thin layer of aluminum oxide (Al2O3) formed by oxidation of aluminum (Al) between the metal/Ge interface. The effective Schottky barrier heights of nickel (Ni)/n type Ge, cobalt (Co)/n type Ge, and iron (Fe)/n type Ge decrease from 0.54, 0.62, and 0.61eV to 0.39, 0.23, and 0.18eV, respectively, with this thin layer of Al2O3. The tunneling oxide significantly suppresses the Fermi level pinning, and yet does not restrict the current density. This method seems promising to realize low resistance metal contact to n type Ge, which is essential to realize n channel Ge complementary metal oxide semiconductor field effect transistor with metal source and drain.", "author_names": [ "Yi Zhou", "Masaaki Ogawa", "Xinhai Han", "Kang L Wang" ], "corpus_id": 119563109, "doc_id": "119563109", "n_citations": 129, "n_key_citations": 5, "score": 0, "title": "Alleviation of Fermi level pinning effect on metal/germanium interface by insertion of an ultrathin aluminum oxide", "venue": "", "year": 2008 }, { "abstract": "Various mechanisms for the Fermi level pinning of p gate metals on HfO2 are analyzed in detail. It is found that for Fermi energies below the Si valence band, HfO2 can oxidize Si by creating positively charged O vacancies. The band bending due to this vacancy concentration can account for the observed Fermi level pinning of p metals on HfO2.", "author_names": [ "John Robertson", "Onise Sharia", "Alexander A Demkov" ], "corpus_id": 123368521, "doc_id": "123368521", "n_citations": 127, "n_key_citations": 1, "score": 0, "title": "Fermi level pinning by defects in HfO2 metal gate stacks", "venue": "", "year": 2007 }, { "abstract": "It is predicted that Schottky barriers of the transition metal dichalcogenides MoSe2, MoTe2, WS2, WSe2, and WTe2 will suffer less from Fermi level pinning by chalcogen vacancies than does MoS2, because their vacancy formation energies are larger. The reduction in vacancy numbers will allow a greater degree of Schottky barrier height tuning by varying metal work function of the contacts in these compounds. The vacancy levels of WS2, WSe2 and MoSe2, and MoTe2 are also calculated to lie nearer midgap, so that ambipolar conduction will be easier in these compounds than in MoS2.", "author_names": [ "Yuzheng Guo", "Dehong Liu", "John Robertson" ], "corpus_id": 123012620, "doc_id": "123012620", "n_citations": 109, "n_key_citations": 0, "score": 0, "title": "Chalcogen vacancies in monolayer transition metal dichalcogenides and Fermi level pinning at contacts", "venue": "", "year": 2015 } ]

[ { "abstract": "Based on an analysis of basic realization possibilities, the structure of the power circuit of a new single stage three phase boost type pulsewidth modulated (PWM) rectifier system (VIENNA Rectifier II) is developed. This system has continuous sinusoidal time behavior of the input currents and high frequency isolation of the output voltage, which is controlled in a highly dynamic manner. As compared to a conventional two stage realization, this system has substantially lower complexity and allows the realization of several isolated output circuits with minimum effort. The basic function of the new PWM rectifier system is described based on the conduction states occurring within a pulse period. Furthermore, a straightforward space vector oriented method for the system control is proposed which guarantees a symmetric magnetization of the transformer. Also, it makes possible a sinusoidal control of the mains phase currents in phase with the associated phase voltages. By digital simulation, the theoretical considerations are verified and the stresses on the power semiconductors of the new converter system are determined. Finally, results of an experimental analysis of a 2.5 kW laboratory prototype of the system are given, and the direct startup and the short circuit protection of the converter are discussed. Also, the advantages and disadvantages of the new converter system are compiled in the form of an overview.", "author_names": [ "Johann Walter Kolar", "Uwe Drofenik", "Franz C Zach" ], "corpus_id": 12353707, "doc_id": "12353707", "n_citations": 72, "n_key_citations": 2, "score": 1, "title": "VIENNA rectifier II a novel single stage high frequency isolated three phase PWM rectifier system", "venue": "IEEE Trans. Ind. Electron.", "year": 1999 }, { "abstract": "Based on an analysis of basic realization possibilities, the structure of the power circuit of a new single stage three phase boost type PWM rectifier system (VIENNA Rectifier II) is developed. This system has continuous sinusoidal time behavior of the input currents and high frequency isolation of the output voltage which is controlled in a highly dynamic manner. As compared to a conventional two stage realization, this system has substantially lower complexity and allows to realize several isolated output circuits with minimum effort. The basic function of the new PWM rectifier system is described based on the conducting states occurring within a pulse period. Furthermore, a straightforward space vector oriented method for the system control is proposed which guarantees a symmetric magnetization of the transformer. Also, it makes possible a sinusoidal control of the mains phase currents in phase with the associated phase voltages. By digital simulation the theoretical considerations, the stresses on the power semiconductors of the new converter system are determined. Finally, problems of a practical realization of the system are discussed, as well as the direct start up and the short circuit protection of the converter. Also, the advantages and disadvantages of the new converter system are compiled in the form of an overview.", "author_names": [ "Johann Walter Kolar", "Uwe Drofenik", "Franz C Zach" ], "corpus_id": 16405912, "doc_id": "16405912", "n_citations": 63, "n_key_citations": 2, "score": 1, "title": "VIENNA rectifier II a novel single stage high frequency isolated three phase PWM rectifier system", "venue": "APEC '98 Thirteenth Annual Applied Power Electronics Conference and Exposition", "year": 1998 }, { "abstract": "An isolated single stage three phase ac dc converter is proposed for aircraft system in this paper. The proposed converter uses the matrix $3 \\times 1$ topology to directly convert three phase line frequency ac voltages into high frequency ac voltage, and therefore facilitates the use of high frequency transformer for galvanic isolation leading to more compact and lighter weight of the power electronic converter. A space vector modulation based switching scheme is proposed and digitally implemented for superior input power quality and improved power conversion efficiency. A current doubler rectifier (CDR) circuit is used at the output side, which essentially reduces the leakage inductance of the high frequency transformer by decreasing the primary to secondary turns ratio. Moreover, an active soft switched lossless snubber circuit is proposed to overcome the high voltage spikes produced due to the leakage inductance of the high frequency transformer. A novel approach of adding a series capacitor in the primary winding of the high frequency transformer for the soft and uninterrupted commutation of the high frequency ac current is presented. The modes of operation of the proposed converter with the CDR circuit are analyzed in detail. Subsequently, the design equations for the proposed converter are derived. Simulation and experimental results are presented for a 500 W prototype converter suitable for aircraft systems.", "author_names": [ "Amit Kumar Singh", "Elango Jeyasankar", "Pritam Das", "Sanjib Kumar Panda" ], "corpus_id": 35025976, "doc_id": "35025976", "n_citations": 36, "n_key_citations": 2, "score": 0, "title": "A Single Stage Matrix Based Isolated Three Phase AC DC Converter With Novel Current Commutation", "venue": "IEEE Transactions on Transportation Electrification", "year": 2017 }, { "abstract": "Three phase power factor correction rectifiers followed by a dc dc isolated converter are widely used for conversion of three phase ac to isolated dc output used for high power telecommunication loads. In this paper, a reduced device count nine switch converter topology, which integrates the two stages of a conventional three phase ac dc power supply with an isolated dc output voltage for telecom applications is proposed. A novel modulation scheme using three separate 120$\\circ phase shifted high frequency carriers for the three legs of the proposed converter is developed to drive the switches. It is shown that such modulation scheme leads to interleaved operation of the three dc dc resonant converters integrated within the proposed topology resulting in low output dc voltage ripple. Justification is provided for the choice of the SiC MOSFET as the enabling technology for the converter. The proposed system with the modulation scheme is validated with a 1.5 kW laboratory prototype, which meets the Energy Star 80PLUS platinum efficiency standard for all loads.", "author_names": [ "Kawsar Ali", "Ravi Kiran Surapaneni", "Pritam Das", "Sanjib Kumar Panda" ], "corpus_id": 28855440, "doc_id": "28855440", "n_citations": 18, "n_key_citations": 1, "score": 0, "title": "An SiC MOSFET Based Nine Switch Single Stage Three Phase AC DC Isolated Converter", "venue": "IEEE Transactions on Industrial Electronics", "year": 2017 }, { "abstract": "High frequency link matrix rectifier (HFLMR) is an isolated single stage three phase ac dc converter, which originates from the three phase matrix converter and inherits the advantages of matrix rectifier such as no dc link components. In this paper, an HFLMR for more electric aircraft system is proposed. The proposed HFLMR consists of a three phase input LC filter, a matrix rectifier, a high frequency transformer, a diode bridge rectifier, and a purely capacitive output filter. The elimination of output filter inductor clamps the output rectifier device off state voltage to the output voltage and eliminates any RC snubber across the rectifier. A novel symmetric modulation scheme based on space vector modulation is implemented to regulate the switching sequences and provide selective natural zero voltage switching and zero current switching of the devices of the matrix bridge. The proposed converter is more power dense since it eliminates the dc link components, output filter inductor, and lossy snubber across the output rectifier devices. A TI digital signal processor TMS320F28379D is used to process the converter signals and generate the gating logic. The proposed converter is validated on a laboratory prototype powered by 115 $V_{{rms} ac with frequency of 400 Hz. The isolated dc output voltage is regulated at 270 V dc and the maximum output power is 600 W.", "author_names": [ "Dongdong Lan", "Pritam Das" ], "corpus_id": 116250967, "doc_id": "116250967", "n_citations": 15, "n_key_citations": 2, "score": 0, "title": "A High Frequency Link Matrix Rectifier With a Pure Capacitive Output Filter in a Discontinuous Conduction Mode", "venue": "IEEE Transactions on Industrial Electronics", "year": 2020 }, { "abstract": "The development of guidelines for the practical application of a new power module (IXYS VUM25 E) realizing a bridge leg of a three phase/switch/level PWM (VIENNA) rectifier system with low effects on the mains is discussed. The inner circuit structure of the power module is formed by a bidirectional bipolar switch and of two free wheeling diodes. In a first step the switching losses of the power MOSFET and of the free wheeling diodes are determined by measurement in dependency on the switched current for characteristic values of the junction temperature. The isolated driving stage of the MOSFET is designed for minimum switching losses considering the occurring switching overvoltages and the ringing between the parasitic circuit elements. The conduction losses of the semiconductor elements are calculated directly via simple analytical approximations of the mean and rms values of the device currents. Based on the knowledge of the dependency of the main loss contributions of the semiconductors of the power module on the operating parameters (mains voltage, output voltage, heat sink temperature and switching frequency) the thermally maximum allowable mains current amplitude is calculated. Furthermore, for different switching frequencies an overview over the power loss contributions of the semiconductor elements is given. Also, the reduction of the efficiency caused by the total semiconductor losses is determined. Finally, the overall efficiency of a PWM (VIENNA) rectifier system realised by using the IXYS VUM25 E module is estimated and further possible developments of this module are discussed.", "author_names": [ "Johann Walter Kolar", "Hans Ertl", "Franz C Zach" ], "corpus_id": 110920945, "doc_id": "110920945", "n_citations": 170, "n_key_citations": 4, "score": 0, "title": "Design and experimental investigation of a three phase high power density high efficiency unity power factor PWM (VIENNA) rectifier employing a novel integrated power semiconductor module", "venue": "Proceedings of Applied Power Electronics Conference. APEC '96", "year": 1996 }, { "abstract": "In this paper a single stage structure is proposed for realizing a three phase unity power factor rectifier. This topology utilizes a forward/flyback transformer to allow the high frequency isolation. The principle of the operation and the applied control concept is discussed. Space vector modulation is used in order to achieve unity power factor and to have the output voltage be regulated. Furthermore, the system transient is analyzed during turn on and a novel method is applied to the control system in order to limit inrush current during startup. The proper operation of the soft start method is confirmed by numerical simulation of a 6KW, 380V/48Vdc. The stability of the closed loop as well as the converter performance is verified by measurements on a low power prototype.", "author_names": [ "Negar Noroozi", "Mohammad Reza Zolghadri" ], "corpus_id": 28428189, "doc_id": "28428189", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "An isolated three phase three switch buck rectifier with inrush current limiting", "venue": "The 6th Power Electronics, Drive Systems Technologies Conference (PEDSTC2015)", "year": 2015 }, { "abstract": "In this paper, a novel three phase matrix based isolated AC DC converter is proposed for DC distribution system. The circuit is derived from boost converter based matrix PWM rectifier by only adding a small commutation capacitor and inductor. Compare to traditional power factor correction rectifier plus DC/DC two stage configuration, the proposed converter has higher efficiency and power density. Soft switching can be realized for all switches and the intermediate DC capacitor is eliminated in the proposed topology. Also, compared to the buck derived single stage solution, it requires smaller size EMI filter in the AC input stage. Furthermore, a novel space vector modulation (SVM) scheme is developed for the converter to control the input current and enable the soft switching operation. In this paper, the topology derivation and circuit operational analysis for soft commutation are given. The proposed SVM scheme is introduced and a simulation is carried out to verify the circuit.", "author_names": [ "Chushan Li", "Yulin Zhong", "David Xu" ], "corpus_id": 38680932, "doc_id": "38680932", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "Soft switching three phase matrix based isolated AC DC converter for DC distribution system", "venue": "2015 IEEE Energy Conversion Congress and Exposition (ECCE)", "year": 2015 }, { "abstract": "Recently an important increase of the electrical equipment in modern aircrafts is leading to an increase in the demand for electrical power. The usual electrical power distribution in aircraft applications is done via a three phase 115Vac grid. A new trend of DC distribution is emerging employing a 270 Vdc grid. This yields the need for high efficiency and high power density AC DC converters, connecting the two grids while providing galvanic isolation. Traditionally 12 pulse autotransformer passive rectifiers are used in aircraft applications. This converter is robust and highly reliable, however it is a non controlled topology and it is relatively heavy because of the low frequency power transformer. Two stage rectifier system approaches, employing three phase PWM rectifiers or active filters and isolated DC DC converters, are good alternatives to be applied in aircraft applications, to reduce the weight by using high frequency transformers and inductors. However, two stage topologies process the energy twice leading to lower efficiency, power density. The reliability is also not very high due to a high semiconductor component count. This paper presents a new isolated single stage PWM rectifier system, based on the recently presented non isolated Swiss rectifier topology, called the Swiss Forward rectifier. The principle of operation of this converter topology is presented together with detailed design guidelines and experimental validation on a 3.3kW 115Vac to 270Vdc prototype.", "author_names": [ "Marcelo Silva", "Nico Hensgens", "Jesus Angel Oliver", "Pedro Alou", "Oscar Garcia", "Jose Antonio Cobos" ], "corpus_id": 26755692, "doc_id": "26755692", "n_citations": 18, "n_key_citations": 2, "score": 0, "title": "Isolated Swiss Forward three phase rectifier for aircraft applications", "venue": "2014 IEEE Applied Power Electronics Conference and Exposition APEC 2014", "year": 2014 }, { "abstract": "With the rapid development of communication industry, high voltage DC power supply system has become a new research direction of communication power. The paper studies the high frequency switching rectifier for high voltage DC power supply system, mainly including the hardware topology and key control strategy. Firstly, the front end converter is applied by a three phase PFC rectifier, and the rectifier with VIENNA topology and related control strategies including capacitor midpoint balance control are analyzed respectively. Secondly, a novel ZVS topology is proposed as the back end converter to optimize the ZVS effect, and an improved PWM control strategy is depicted to optimize the control scheme of lag switching according in light load case. At the same time, the key control loop under a variety of working conditions is depicted. Finally a 6 kW prototype of HVDC rectifier is developed to evaluate the previous theoretical analysis.", "author_names": [ "Zte Corporatio" ], "corpus_id": 112387877, "doc_id": "112387877", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "High Frequency Switching Rectifier in HVDC Power Supply System", "venue": "", "year": 2014 } ]

[ { "abstract": "It is worldwide accepted that a real breakthrough in Power Electronics mainly comes Wide Band Gap (WBG) semiconductor devices. WBG semiconductors such as SiC, GaN, and diamond show superior material properties, which allow operation at high switching speed, high voltage and high temperature. These unique performances provide a qualitative change in their application to energy processing. From energy generation to the end user, the electric energy undergoes a number of conversions. Which are currently highly inefficient to the point that it is estimated that only 20% of the whole energy involved in energy generation reaches the end user. WGB semiconductors increase the conversion efficiency thanks to their outstanding material properties. The recent progress in the development of high voltage WBG power semiconductor devices, especially SiC and GaN, is reviewed.", "author_names": [ "Jose Millan" ], "corpus_id": 5445041, "doc_id": "5445041", "n_citations": 91, "n_key_citations": 1, "score": 0, "title": "Wide Band Gap power semiconductor devices", "venue": "2013 Spanish Conference on Electron Devices", "year": 2013 }, { "abstract": "Due to the material limitations, the traditional silicon based power devices approach the intrinsic limits of the material in many ways. The silicon based devices have not been applicable to high voltage, high frequency, high temperature, high efficiency and high power density applications. Due to the wide band gap semiconductor devices having unmatched electrical performance of the silicon based devices, it can significantly reduce the weight of the inverter, volume, cost, and enhance efficiency and power density power electronic devices, which can withstand higher value, faster switching speeds, lower switching losses and higher operating junction temperature. The subject of high efficiency, high power density in the rail transit electrical drive demand as the background, the key technology research of high power converter based on the wide band gap power semiconductor devices is proposed. First, the topological structure of power electronic traction transformer is given. Then, the system control strategies including cascaded H bridge single phase rectifier, dual active H bridge converter control, inverter traction motor vector control, and auxiliary converter output voltage control are given. Related research will provide a solid foundation in the development of the wide band gap power devices and the high voltage large capacity device applications.", "author_names": [ "Lu Zhao", "Qiongxuan Ge", "Zhida Zhou", "Bo Yang", "Yaohua Li" ], "corpus_id": 189824450, "doc_id": "189824450", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Research of high power converter based on the wide band gap power semiconductor devices for rail transit electrical drive", "venue": "2018 1st Workshop on Wide Bandgap Power Devices and Applications in Asia (WiPDA Asia)", "year": 2018 }, { "abstract": "Wide band gap materials such as Gallium Nitride (GaN) and Silicon Carbide (SiC) offer improved performance for power electronic devices compared to traditional Silicon (Si) power semiconductor devices. This paper investigates a 600V GaN Silicon CoolMOS transistor application in 400W single phase continuous conduction mode (CCM) Boost PFC converter circuits with GaN, SiC and ultrafast silicon diodes and compares power semiconductor device efficiency benefits. The 600V GaN Silicon CoolMOS transistor power efficiency improvement study and loss analysis for CCM Boost PFC converter circuits are introduced in detail. Based on the experimental study, the 600V GaN transistor enables higher energy efficiency compared with 600V Si CoolMOS for CCM Boost PFC converter at 680 kHz switching frequency: around 1% higher at low line and about 0.5% higher at high line due to low switching loss. 600V SiC diode typically outperforms ultrafast Si diode GaN diode for CCM Boost PFC converter due to low device charge, and forward voltage. 600V GaN diode suffers lowest efficiency at light load due to large device capacitive charge. The ultrafast Silicon diode has the highest efficiency at light load due to low device charge, but suffers from low efficiency at heavy load due to largest forward voltage and reverse recovery loss. According to the investigations, the combination of a 600V GaN transistor for the boost switch and a SiC rectifier for the freewheeling diode achieves the best efficiency for CCM Boost PFC converter with the lowest power loss.", "author_names": [ "Saijun Mao", "Ramanujam Ramabhadran", "Jelena Popovic", "Jan Abraham Ferreira" ], "corpus_id": 41113201, "doc_id": "41113201", "n_citations": 20, "n_key_citations": 0, "score": 0, "title": "Investigation of CCM boost PFC converter efficiency improvement with 600V wide band gap power semiconductor devices", "venue": "2015 IEEE Energy Conversion Congress and Exposition (ECCE)", "year": 2015 }, { "abstract": "Wide band gap devices are highly suitable to harsh working conditions such as high voltage, high temperature, high frequency, and high radiation exposure. The working voltage can reach as high as 10,000 volt, while the heat flux can exceed 1 *107 W/m2, which is far beyond the realm of Si devices. Applications include spaceship, airplane, high speed train, ocean oil drilling platform, EV /HEV and intelligent manufacturing. Application areas of internet of things (loT) require new technologies such as power electronics, RF devices and solid state lighting.", "author_names": [ "Braham Ferreira" ], "corpus_id": 12131626, "doc_id": "12131626", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "International technology roadmap for wide band gap power semiconductor ITRW", "venue": "2016 International Symposium on 3D Power Electronics Integration and Manufacturing (3D PEIM)", "year": 2016 }, { "abstract": "It is worldwide accepted that a real breakthrough in Power Electronics mainly comes Wide Band Gap (WBG) semiconductor devices. WBG semiconductors such as SiC, GaN, and diamond show superior material properties, which allow operation at high switching speed, high voltage and high temperature. These unique performances provide a qualitative change in their application to energy processing. From energy generation to the end user, the electric energy undergoes a number of conversions. Which are currently highly inefficient to the point that it is estimated that only 20% of the whole energy involved in energy generation reaches the end user. WGB semiconductors increase the conversion efficiency thanks to their outstanding material properties. The recent progress in the development of high voltage WBG power semiconductor devices, especially SiC and GaN, is reviewed.", "author_names": [ "Jose Millan", "Philippe Godignon" ], "corpus_id": 110683893, "doc_id": "110683893", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Wide Band Gap power semiconductor devices", "venue": "", "year": 2013 }, { "abstract": "MAHAJAN ANIURUDHA ATUL. Characterization of Wide Band Gap Power Semiconductor Devices. (Under the direction of Dr. Subhashish Bhattacharya) Power semiconductor devices are the main building blocks for power conversion systems. Wide band gap power devices offer advantages like improved efficiency and low system cost. This work includes the static and switching characterization of Gallium Nitride and Silicon Carbide wide band gap transistors. The characterization procedures are explained. The characterization results are compared for various transistors and advantages of these transistors over Silicon based transistors are discussed. The results are obtained by building a hardware characterization setup in the lab. (c) Copyright 2016 Anirudha Atul Mahajan", "author_names": [ "A Mahajan" ], "corpus_id": 38679532, "doc_id": "38679532", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Characterization of Wide Band Gap Power Semiconductor Devices.", "venue": "", "year": 2016 }, { "abstract": "Power electronics switching devices involving Wide Band Gap (WBG) materials such as silicon carbide (SiC) and gallium nitride (GaN) provide a substantial switching level improvements as compared to the silicon (Si) devices. Recently Si MOSFETs are also being superseded by silicon carbide (SiC) and gallium nitride (GaN) MOSFETs due to their superior performance in high temperature limits. In order to directly compare these two types of MOSFETs we study their various parameters like energy band gap, carrier mobility, saturation velocity and thermal conductivity. A study has also been conducted to see the effect of high temperatures on electrical properties. A circuit analysis tool Pspice is used to study these two types of MOSFETs.", "author_names": [ "Faisal Mehmood Shah", "Han Min Xiao", "Muhammad Awais" ], "corpus_id": 220480052, "doc_id": "220480052", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Electro thermal Comparative Analysis and Simulation of Wide Band Gap Semiconductor Materials for Power Electronic Devices", "venue": "", "year": 2020 }, { "abstract": "", "author_names": [ "Bilal Ahmad" ], "corpus_id": 113427999, "doc_id": "113427999", "n_citations": 3, "n_key_citations": 1, "score": 0, "title": "Wide Band Gap Power Semiconductor Devices and their Applications", "venue": "", "year": 2015 }, { "abstract": "", "author_names": [ "Hiroki Takahashi", "Takeshi Anzai", "Fumiki Kato", "Shinji Sato", "Hidekazu Tanisawa", "Yoshinori Murakami", "Kinuyo Watanabe", "Hiroshi Sato" ], "corpus_id": 110080440, "doc_id": "110080440", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Invited) Baseplate Materials for Securing Reliability of Wide Band Gap Power Semiconductor Module Operating at High Temperatures", "venue": "", "year": 2015 }, { "abstract": "The commercialization of wide band gap devices such as silicon carbide and gallium nitride transistors has made it possible for power electronics applications to achieve unprecedented performance in terms of efficiency and power density. However, the device characteristics which make this performance possible also create secondary consequences in these high performance applications. One such consequence which is particularly difficult to manage in the context of power electronics applications is the occurrence of self sustained oscillation. This problem has been recognized in the power electronics literature, but heretofore has not received an extensive analytical treatment. This dissertation provides a comprehensive analytical treatment of the self sustained oscillation phenomenon, logically separated into two components: an initial forced cycle and the subsequent oscillatory behavior. A large signal model has been developed in order to predict the occurrence of the initial forced cycle based on a set of estimated initial conditions derived from a user specified operating point. The establishment of the initial forced cycle as predicted by the large signal model creates the bias conditions necessary for the analytical treatment of the subsequent oscillatory behavior. For this purpose, a small signal model is presented which describes this phenomenon on the basis of recognizing the wide band gap device and a minimal set of parasitic components associated with the gate and drain circuits as an unintended negative conductance oscillator. In the context of established oscillator design theory it has been shown both analytically and with simulation that negative differential conductance exhibited by the parasitic model explains the conditions under which self sustained oscillation is likely to occur. Both the large signal and small signal models are shown to demonstrate good agreement with empirical results from pulsed switching experiments obtained over a wide range of operating conditions. In addition, a catalog of known solutions to the problem of self sustained oscillation is presented, along with a discussion of a method by which the current work can be used by application designers to preclude the occurrence of this phenomenon in practical systems by design.", "author_names": [ "Andrew N Lemmon" ], "corpus_id": 111502884, "doc_id": "111502884", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "On the stability of circuits switched by wide band gap power semiconductor devices", "venue": "", "year": 2013 } ]

[ { "abstract": "Effective theoretical models are needed to predict the physical properties of materials. Here we discuss the electronic structure of rhenium carbonitride (ReCN) in terms of tight binding. The extended Huckel tight binding (EHTB) formalism was employed to calculate the band structure, density of states (DOS) and investigate the chemical bonding properties as well as the crystal field splitting (CFS) of d orbitals in the Re atom. Two ReCN structures were studied, characterized by space groups P63mc and P3m1, respectively. The calculated energy bands and DOS depict semiconductor properties for both structures, seeing an indirect band gap of 0.62 eV in P63mc (M K) while a direct band gap of 0.49 eV is seen in P3m1 at (H) Mulliken population and CFS analysis were done to gain insight into the filling of 5d orbitals in ReCN, crystallographical differences between the two crystal structures and their physical implications. The five fold degenerate energy levels in both the P63mc and P3m1 structures are broken by a tetragonal crystal electric field. The P63mc structure undergoes Peierls distortion, resulting in a loss of symmetry. The EHTB method is an effective tool to approximate the physical and chemical properties of novel materials such as ReCN at a low computational cost and in terms of a simple quantum mechanical framework, understood by the broader community. The EHTB model for ReCN will serve as a benchmark and starting point for future studies on the compound within similar contexts.", "author_names": [ "Etienne Palos", "Jose I Paez", "Armando Reyes-Serrato", "Donald H Galvan" ], "corpus_id": 125463194, "doc_id": "125463194", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Electronic structure calculations for rhenium carbonitride: an extended Huckel tight binding study", "venue": "", "year": 2018 }, { "abstract": "Abstract Electronic structures of nine cubic perovskite type oxides ABO3's including SrTiO3, SrZrO3, SrHfO3, BaTiO3, BaZrO3, BaHfO3, PbTiO3, PbZrO3 and PbHfO3 were calculated using a band theory based on the self consistent charge extended Huckel tight binding (SCC XHTB) method incorporating the relativistic effects except for the spin orbit interaction in order to examine how the electronic structure changes due to the substitution of the A or B site atom. Moreover, calculations were also made for the tetragonal PbTiO3 to study the electronic structural changes due to the structural change from the cubic phase to the tetragonal one. It is shown that the upper valence band of all the ABO3's considered in the present paper consists of the 2p orbital of oxygen mixed with the d valence electrons of the B atom. The shape remains nearly the same in spite of the A or B site substitution. For the conduction band, it is shown that the bottom of which is made up from the ndt 2g band of the B atom for SrTiO3, SrZrO.", "author_names": [ "Michihide Kitamura", "Hayden Chen" ], "corpus_id": 122338567, "doc_id": "122338567", "n_citations": 20, "n_key_citations": 0, "score": 0, "title": "Electronic structure calculations of perovskite type oxides using the self consistent charge extended Huckel tight binding method", "venue": "", "year": 1998 }, { "abstract": "To gain insight into the electronic properties of MoSe2 (molybdenum selenide, also known as drysdallite) electronic structure calculations, total and projected density of states, crystal orbital overlap population and Mulliken population analysis were performed. The calculated energy bands depict a semiconductor behavior with a direct gap (at K) of 0.91 eV and an indirect gap (from G to K) of 3.6 eV, respectively. Total and projected density of states provided information about the contribution from each orbital of each atom to the total density of states. Moreover, the bonding strength between some atoms within the unit cell was obtained. Mulliken population analysis corroborates the electron filling of the Mo dz2 orbitals in agreement with another experimental and theoretical results.", "author_names": [ "Donald H Galvan" ], "corpus_id": 122196158, "doc_id": "122196158", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "ELECTRONIC STRUCTURE CALCULATIONS FOR MoSe2 USING EXTENDED HUCKEL TIGHT BINDING METHOD", "venue": "", "year": 2004 }, { "abstract": "A transferable tight binding parametrization procedure for extended Huckel approximation is proposed, with the charge self consistent scheme, that could be applied to the quantum molecular dynamics (MD) simulation for long time dynamics of large scale systems. In this procedure, either a target molecule is divided into small molecules or another realistic set of small molecules characterizing chemical bonds in the complicated target molecule is adopted. Then, the parameters for these small molecules are adjusted and compared with reference results of energy levels and wave functions by, for example, density functional theory. Upon application to the large target molecule, these parameters are then readjusted directly in the target molecule. An example is demonstrated with MD simulation applied to the ionic liquid molecule N methyl N propylpiperidinium bis trifluoromethanesulfonyl imide (PP13 TFSI) The origin and stability of HOMO LUMO gap are discussed.", "author_names": [ "Shinya Nishino", "Takeo Fujiwara" ], "corpus_id": 42227752, "doc_id": "42227752", "n_citations": 3, "n_key_citations": 1, "score": 0, "title": "Parametrization scheme with accuracy and transferability for tight binding electronic structure calculations with extended Huckel approximation and molecular dynamics simulations", "venue": "Journal of Molecular Modeling", "year": 2013 }, { "abstract": "Abstract The spin polarized self consistent charge extended Huckel tight binding (SP SCC XHTB) method has been developed by authors to study the electronic structures of rutile type transition metal dioxides, MO2, with both the nonmagnetic and magnetic phases. This method has been used to successfully predict the electronic structures of nonmagnetic (n) MO2's with M =Ti, V, Nb, Ta, Cr and ferromagnetic (f) CrO2, but is inadequate to predict the value of the energy gap of a semiconductive n MnO2. The SP SCC XHTB band structure calculation, which includes all the relativistic effects in a first principal manner, has only one empirical parameter on the evaluation of the matrix elements of the non relativistic Hamiltonian H0. In this paper, the SP SCC XHTB method is improved so as to evaluate the matrix elements of the H0 in a more appropriate manner. The band structure calculations are carried out for the n MO2's with M =Ti, V, Nb, Ta, Cr and Mn, the f CrO2 and the af MnO2. With the improvement it is shown that the SP SCC IXHTB band structure calculations give reasonable results for the electronic structures of all the MO2's considered in the present paper.", "author_names": [ "Michihide Kitamura", "Kanryu Inoue", "Haydn H D Chen" ], "corpus_id": 96680001, "doc_id": "96680001", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Improvement of the spin polarized self consistent charge extended Huckel tight binding method", "venue": "", "year": 2000 }, { "abstract": "The extended Huckel (eH) tight binding method has historically been prized for its computational ease and intuitive chemical clarity. However, its lack of quantitative predictiveness has prevented the eH method from being used as a tool for rapidly screening materials for desired electronic properties. In this work, we demonstrate that when eH input parameters are calibrated using density functional theory (DFT) calculations of carefully chosen sets of simple crystals, the eH parameters retain most of their quantitative accuracy when transferred to more complex, structurally related phases. Using solar energy relevant semiconductors and insulators in the Sr Ti O family as a case study, we show that calibrated eH parameters can match the features of DFT band structures within about two tenths of an eV, at a tiny fraction of the computational cost of DFT.", "author_names": [ "Linda Grabill", "Robert F Berger" ], "corpus_id": 49671161, "doc_id": "49671161", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Calibrating the Extended Huckel Method to Quantitatively Screen the Electronic Properties of Materials", "venue": "Scientific Reports", "year": 2018 }, { "abstract": "In this work, we present a theoretical study of the electronic properties of group IV element nanosheets, namely graphene, silicene, germanene and the corresponding hydrogenated structures for the two latter, silicane and germanane. We compare the results of two different calculation methods, Density Functional Theory (DFT) and Extended Huckel Theory (EHT) for both pristine sheets and sheets of silicene and germanene with a single atom vacancy. We show that EHT offers a remarkably reliable description of the electronic structure of these materials for all cases, thus offering an affordable way for studying large systems for which DFT calculations would be expensive and lengthy.", "author_names": [ "Adriano S Martins", "Marcos Verissimo-Alves" ], "corpus_id": 26611737, "doc_id": "26611737", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Group IV nanosheets with vacancies: a tight binding extended Huckel study.", "venue": "Journal of physics. Condensed matter an Institute of Physics journal", "year": 2014 }, { "abstract": "In this work, we performed tight binding calculations of the electronic structure of III V semiconductors compounds and their alloys based on the Extended Huckel Theory (EHT) In particular, this paper is focused on the dependency between band gap and the applied pressure and also the alloy composition.", "author_names": [ "Ingrid A Ribeiro", "Fabio J Ribeiro", "Adriano S Martins" ], "corpus_id": 118453333, "doc_id": "118453333", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "An extended Huckel study of the electronic properties of III V compounds and their alloys", "venue": "", "year": 2014 }, { "abstract": "Abstract Band theory based on the spin polarized self consistent charge extended Huckel tight binding (SP SCC XHTB) method, which includes all the relativistic effects and the spin polarized self consistent field (SP SCF) atomic structure calculation based on the Hartree Fock Slater method, has been applied to the electronic structure calculations of tetragonal rutile type MO2s, such as nonmagnetic (n) TiO2, VO2, NbO2, TaO2, CrO2, MnO2, ferromagnetic (f) CrO2 and antiferromagnetic (af) MnO2. It is shown that the calculations are consistent with the experimental observations for all systems except the case of MnO2. It is demonstrated that the semiconductive nature of MnO2 can be explained by adding an assumption that three electrons in the Mn t2g orbital are localized in the crystal into the SP SCC XHTB band structure calculation.", "author_names": [ "Michihide Kitamura", "Kanryu Inoue", "Haydn H D Chen" ], "corpus_id": 97423008, "doc_id": "97423008", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Electronic structures of transition metal dioxides studied by the spin polarized self consistent charge extended Huckel tight binding method", "venue": "", "year": 1998 }, { "abstract": "We perform extended calculations of composed carbon structures where carbon acquires its sp or sp hybrid character. Based on an existing implementation of a tight binding (TB) model for carbon, we implement the calculation of the forces using the Hellmann Feynman theorem. The forces make it possible to use fast minimization algorithms to relax carbon nanostructures composed of up to several hundred atoms. We focus our investigation on carbynes (sp character) inserted in a nanohole inside a graphene sheet (sp character) and on carbon nanotubes mainly (sp character) After relaxation we compute the electronic structure, in particular we evaluated the band gaps for semiconducting nanotubes. The results are compared to DFT calculation and experimental observations. Finally, taking advantage of the forces, we perform molecular dynamics simulations of carbynes in graphene at high temperature, to investigate the stability of such a system. Advisor: Dr. Nicola Manini Co Advisor: Prof. Giovanni Onida", "author_names": [ "Nicola Manini", "Giovanni Onida", "Nicola Ferri" ], "corpus_id": 29348759, "doc_id": "29348759", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Universita degli Studi di Milano Facolta di Scienze Matematiche Fisiche e Naturali Laurea Triennale in Fisica Structural and electronic properties of carbon nanostructures a tight binding study", "venue": "", "year": 2010 } ]

[ { "abstract": "Defect inspection (to detect, classify, measure and analyze) has long been a challenging task in semiconductor manufacturing (MFG) domain. This paper discusses a new Machine Learning (ML) approach which can be used to assist defect inspection in different MFG scenarios. Associated solutions have been developed and applied to the surface defect inspection for substrate components, used in our IC packaging MFG.During the past decade, the help from image based Automated Optical Inspection (AOI) equipment has significantly reduced manual efforts in substrate/PCB defect examination, but is still insufficient in defect classification automation. Recently, the adoption of ML and Convolution Neural Network (CNN) based Deep Learning technologies raised much hoping to advance the defect classification automation to a new level that acceptable for rigid MFG practices. Most of the published CNN models, however, tend to use large number of learning parameters (floating point variables) during computing in order to gain high image recognition accuracy. The parameters' massive blow up often causes heavy power gobbling computation. While applying CNN to our substrate defect datasets, each of which contains hundreds of thousands of high resolution images, collected across different MFG processes and produced products, a training run could take days or even weeks to finish. Also, more the learning variables for training are used, longer the inference time will be. The situations make these complex CNN models hard to meet our overnight retraining and in line inference time constraint. Therefore, to develop a more efficient ML method is strongly preferred in our MFG environment.In this paper, we develop a feature spanning ML approach which takes the feature of an image as a base. Through mathematical transformations the base is spanned to fit into an accumulated and gradually divided feature of classes space. During the feature spanning process, the initialization of parameters is tightly controlled, which means the redundancy blow up is carefully calculated to optimize the usage of computation resource.To demonstrate the advantage of our ML method, the public dataset CIFAR 10 is used for benchmarking. CIFAR 10 dataset contains sufficient diversity and is small enough to have quick observations on computing performance. Our results indicate that the parameters used by our method are only 5.6% of ResNet 101's. We also apply this new ML technology to the inspection of several substrate defect types. In particular, defects on solder mask are hard to be recognized because their pattern's colors are quite similar to the substrate background. The benchmarking shows very competitive results as compared with other CNNs' Further benchmarking shows our ML method holds high degree of shift invariance property, implying that our method can help to resist MFG condition changes during the defect inspection operation.Our ML approach requires much less learning variables, and thus can achieve very fast training and inference speed. While adopted in MFG production lines, it helps to reduce computing cost/energy and comply with Green Factory policy. Besides, our ML technology has high scalability, capable of performing heterogeneous learning on data combined from different aspects, such as image plus CAM design reference, Z height or time series signal waveform. For continuous development efforts, we are making the ML behavior in our AI for MFG applications more explainable, controllable, and be self adaptive to changes in MFG environment.", "author_names": [ "Yi-Chung Hsu", "Ping-Yen Kuo", "Wong-Shian Huang" ], "corpus_id": 212647458, "doc_id": "212647458", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "A Novel Feature spanning Machine Learning Technology for Defect Inspection", "venue": "2019 14th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT)", "year": 2019 }, { "abstract": "Automated visual inspection in the semiconductor industry aims to detect and classify manufacturing defects utilizing modern image processing techniques. While an earliest possible detection of defect patterns allows quality control and automation of manufacturing chains, manufacturers benefit from an increased yield and reduced manufacturing costs. Since classical image processing systems are limited in their ability to detect novel defect patterns, and machine learning approaches often involve a tremendous amount of computational effort, this contribution introduces a novel deep neural network based hybrid approach. Unlike classical deep neural networks, a multi stage system allows the detection and classification of the finest structures in pixel size within high resolution imagery. Consisting of stacked hybrid convolutional neural networks (SH CNN) and inspired by current approaches of visual attention, the realized system draws the focus over the level of detail from its structures to more task relevant areas of interest. The results of our test environment show that the SH CNN outperforms current approaches of learning based automated visual inspection, whereas a distinction depending on the level of detail enables the elimination of defect patterns in earlier stages of the manufacturing process.", "author_names": [ "Tobias Schlosser", "Frederik Beuth", "Michael Friedrich", "Danny Kowerko" ], "corpus_id": 204822664, "doc_id": "204822664", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "A Novel Visual Fault Detection and Classification System for Semiconductor Manufacturing Using Stacked Hybrid Convolutional Neural Networks", "venue": "2019 24th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)", "year": 2019 }, { "abstract": "An automatic defect classification (ADC) system identifies and classifies wafer surface defects using scanning electron microscope images. By classifying defects, manufacturers can determine whether the wafer can be repaired and proceed to the next fabrication step. Current ADC systems have high defect detection performance. However, the classification power is poor. In most work sites, defect classification is performed manually using the naked eye, which is unreliable. This paper proposes an ADC method based on deep learning that automatically classifies various types of wafer surface damage. In contrast to conventional ADC methods, which apply a series of image recognition and machine learning techniques to find features for defect classification, the proposed model adopts a single convolutional neural network (CNN) model that can extract effective features for defect classification without using additional feature extraction algorithms. Moreover, the proposed method can identify defect classes not seen during training by comparing the CNN features of the unseen classes with those of the trained classes. Experiments with real datasets verified that the proposed ADC method achieves high defect classification performance.", "author_names": [ "Sejune Cheon", "Hankang Lee", "Chang Ouk Kim", "Seok Hyung Lee" ], "corpus_id": 116334837, "doc_id": "116334837", "n_citations": 52, "n_key_citations": 1, "score": 1, "title": "Convolutional Neural Network for Wafer Surface Defect Classification and the Detection of Unknown Defect Class", "venue": "IEEE Transactions on Semiconductor Manufacturing", "year": 2019 }, { "abstract": "Abstract The similarity of gray characteristics and shapes of the defects, stems, and calyxes in apple images is a difficult challenge for automatic identification and detection of apple defects in the machine vision field. This paper attempts towards finding an automatic and efficient way to identify apple defects. An automatic detection method is proposed for apple defects based on laser induced light backscattering imaging and convolutional neural network (CNN) algorithm. Laser backscattering spectroscopic images of apples are obtained using semiconductor laser. We take preprocessing steps to get the finest image dataset for CNN. An AlexNet model with an 11 layer structure is established and trained to identify apple defects. We analyze how well the model does with the recognition effects of apple defects. The proposed CNN model for the detection of apple defects achieves a higher recognition rate of 92.5% and the accuracy is better than conventional machine learning algorithms. The method based on laser backscattering imaging analysis and CNN theory provides an idea and theoretical basis for efficient, non destructive, and online detection of fruits quality.", "author_names": [ "Ang Wu", "Juan-hua Zhu", "Taiyong Ren" ], "corpus_id": 209069867, "doc_id": "209069867", "n_citations": 11, "n_key_citations": 2, "score": 0, "title": "Detection of apple defect using laser induced light backscattering imaging and convolutional neural network", "venue": "Comput. Electr. Eng.", "year": 2020 }, { "abstract": "With semiconductor technology progressing beyond 5nm node, there is tremendous pressure on computational lithography to achieve both accuracy and speed. One very promising technique to accomplish this mission is to take full advantage of the maturing machine learning techniques based on neural network architecture. Some success has been achieved using convolution neural network (CNN) to obtain inverse lithography technology (ILT) solution with significantly less computational time. In general, CNN architecture consists of feature extraction layers and nonlinear mapping function construction layers. To train a CNN model requires a large amount of data and computational resource. To maintain certain intrinsic symmetries of imaging behavior, the feature extraction layers must be carefully engineered using weight sharing techniques or using well balanced training samples of different orientations, otherwise, feature extraction part will be skewed. It is therefore very desired to have a scheme that can obtain optimal feature vector for machine learning based computational lithography automatically without the need of feature extraction layers in CNN. In this paper, we will make an attempt to describe such a scheme and present our test results on machine learning based OPC and ILT solution. It should be understood that machine learning based computational lithography solutions do not possess the capability to replace conventional OPC or ILT completely due to its lack of required accuracy. However, it can provide an initial solution that is close enough to final OPC solution or ILT solution, therefore fast OPC and fast ILT can be realized.", "author_names": [ "Xuelong Santa Clara Shi", "Yuhang Zhao", "Shoumian Cheng", "Ming Li", "Wei Yuan", "Leon Yao", "Wenhao Zhao", "Yanjun Xiao", "Xiao Hui Kang", "Angmar Li" ], "corpus_id": 108401167, "doc_id": "108401167", "n_citations": 2, "n_key_citations": 1, "score": 0, "title": "Optimal feature vector design for computational lithography", "venue": "Advanced Lithography", "year": 2019 }, { "abstract": "Computer vision and classification methods have become increasingly wide spread in recent years due to ever increasing access to computation power. Advances in semiconductor devices are the basis for this growth, but few publications have probed the benefits of data driven methods for improving a critical component of semiconductor manufacturing, the detection and inspection of defects for such devices. As defects become smaller, intensity threshold based approaches eventually fail to adequately discern differences between faulty and non faulty structures. To overcome these challenges we present machine learning methods including convolutional neural networks (CNN) applied to image based defect detection. These images are formed from the simulated scattering of realistic geometries with and without key defects while also taking into account line edge roughness (LER) LER is a known and challenging problem in fabrication as it yields additional scattering that further complicates defect inspection. Simulating images of an intentional defect array, a CNN approach is applied to extend detectability and enhance classification to these defects, even those that are more than 20 times smaller than the inspection wavelength.", "author_names": [ "Mark-Alexander Henn", "Hui Zhou", "Bryan M Barnes" ], "corpus_id": 202766403, "doc_id": "202766403", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Data driven approaches to optical patterned defect detection.", "venue": "OSA continuum", "year": 2019 }, { "abstract": "Computer vision and classification methods have become increasingly wide spread in recent years due to ever increasing access to computation power. Advances in semiconductor devices are the basis for this growth, but few publications have probed the benefits of data driven methods for improving a critical component of semiconductor manufacturing, the detection and inspection of defects for such devices. As defects become smaller, intensity threshold based approaches eventually fail to adequately discern differences between faulty and non faulty structures. To overcome these challenges we present machine learning methods including convolutional neural networks (CNN) applied to image based defect detection. These images are formed from the simulated scattering of realistic geometries with and without key defects while also taking into account line edge roughness (LER) LER is a known and challenging problem in fabrication as it yields additional scattering that further complicates defect inspection. Simulating images of an intentional defect array, a CNN approach is applied to extend detectability and enhance classification to these defects, even those that are more than 20 times smaller than the inspection wavelength. (c) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement", "author_names": [ "" ], "corpus_id": 202896944, "doc_id": "202896944", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Data driven approaches to optical patterned defect detection", "venue": "", "year": 2019 }, { "abstract": "With the development of machine learning technology, the exploration of energy efficient and flexible architectures for object inference algorithms is of growing interest in recent years. However, not many publications concentrate on a coarse grained reconfigurable architecture (CGRA) for object inference algorithms. This paper provides a stream processing, dual track programming CGRA based approach to address the inherent computing characteristics of algorithms in object inference. Based on the proposed approach, an architecture called stream dual track CGRA (SDT CGRA) is presented as an implementation prototype. To evaluate the performance, the SDT CGRA is realized in Verilog HDL and implemented in Semiconductor Manufacturing International Corporation 55 nm process, with the footprint of 5.19 mm2 at 450 MHz. Seven object inference algorithms, including convolutional neural network (CNN) {k} means, principal component analysis (PCA) spatial pyramid matching (SPM) linear support vector machine (SVM) Softmax, and Joint Bayesian, are selected as benchmarks. The experimental results show that the SDT CGRA can gain on average 343.8 times and 17.7 times higher energy efficiency for Softmax, PCA, and CNN, 621.0 times and 1261.8 times higher energy efficiency for {k} means, SPM, linear SVM, and Joint Bayesian algorithms when compared with the Intel Xeon E5 2637 CPU and the Nvidia TitanX graphics processing unit. When compared with the state of the art solutions of AlexNet on field programmable gate array and CGRA, the proposed SDT CGRA can achieve a 1.78 times increase in energy efficiency and a 13 times speedup, respectively.", "author_names": [ "Xitian Fan", "Di Wu", "Wei Cao", "Wayne Luk", "Lingli Wang" ], "corpus_id": 44068834, "doc_id": "44068834", "n_citations": 11, "n_key_citations": 1, "score": 0, "title": "Stream Processing Dual Track CGRA for Object Inference", "venue": "IEEE Transactions on Very Large Scale Integration (VLSI) Systems", "year": 2018 }, { "abstract": "Computation in memory (CIM) is a promising avenue to improve the energy efficiency of multiply and accumulate (MAC) operations in AI chips. Multi bit CNNs are required for high inference accuracy in many applications [1 5] There are challenges and tradeoffs for SRAM based CIM: (1) tradeoffs between signal margin, cell stability and area overhead; (2) the high weighted bit process variation dominates the end result error rate; (3) trade off between input bandwidth, speed and area. Previous SRAM CIM macros were limited to binary MAC operations for fully connected networks [1] or they used CIM for multiplication [2] or weight combination operations [3] with additional large area near memory computing (NMC) logic for summation or MAC operations.", "author_names": [ "Xin Si", "Ssu-Yen Wu" ], "corpus_id": 71150229, "doc_id": "71150229", "n_citations": 60, "n_key_citations": 8, "score": 0, "title": "24.5 A Twin 8T SRAM Computation In Memory Macro for Multiple Bit CNN Based Machine Learning", "venue": "2019 IEEE International Solid State Circuits Conference (ISSCC)", "year": 2019 }, { "abstract": "A computer aided diagnosis (CAD) system based on mammograms enables early breast cancer detection, diagnosis, and treatment. However, the accuracy of the existing CAD systems remains unsatisfactory. This paper explores a breast CAD method based on feature fusion with convolutional neural network (CNN) deep features. First, we propose a mass detection method based on CNN deep features and unsupervised extreme learning machine (ELM) clustering. Second, we build a feature set fusing deep features, morphological features, texture features, and density features. Third, an ELM classifier is developed using the fused feature set to classify benign and malignant breast masses. Extensive experiments demonstrate the accuracy and efficiency of our proposed mass detection and breast cancer classification method.", "author_names": [ "Zhiqiong Wang", "Mo Li", "Huaxia Wang", "Hanyu Jiang", "Yu-dong Yao", "Hao Zhang", "Junchang Xin" ], "corpus_id": 68066662, "doc_id": "68066662", "n_citations": 65, "n_key_citations": 3, "score": 0, "title": "Breast Cancer Detection Using Extreme Learning Machine Based on Feature Fusion With CNN Deep Features", "venue": "IEEE Access", "year": 2019 } ]

[ { "abstract": "Semiconductor devices have become indispensable for generating electromagnetic radiation in everyday applications. Visible and infrared diode lasers are at the core of information technology, and at the other end of the spectrum, microwave and radio frequency emitters enable wireless communications. But the terahertz region (1 10 THz; 1 THz 1012 Hz) between these ranges has remained largely underdeveloped, despite the identification of various possible applications for example, chemical detection, astronomy and medical imaging. Progress in this area has been hampered by the lack of compact, low consumption, solid state terahertz sources. Here we report a monolithic terahertz injection laser that is based on interminiband transitions in the conduction band of a semiconductor (GaAs/AlGaAs) heterostructure. The prototype demonstrated emits a single mode at 4.4 THz, and already shows high output powers of more than 2 mW with low threshold current densities of about a few hundred A cm 2 up to 50 K. These results are very promising for extending the present laser concept to continuous wave and high temperature operation, which would lead to implementation in practical photonic systems.", "author_names": [ "Rudeger Kohler", "Alessandro Tredicucci", "Fabio Beltram", "Harvey E Beere", "Edmund H Linfield", "A Giles Davies", "David A Ritchie", "Rita Claudia Iotti", "Fausto Rossi" ], "corpus_id": 4422664, "doc_id": "4422664", "n_citations": 2221, "n_key_citations": 46, "score": 0, "title": "Terahertz semiconductor heterostructure laser", "venue": "Nature", "year": 2002 }, { "abstract": "Achieving optical gain and/or lasing in silicon has been one of the most challenging goals in silicon based photonics because bulk silicon is an indirect bandgap semiconductor and therefore has a very low light emission efficiency. Recently, stimulated Raman scattering has been used to demonstrate light amplification and lasing in silicon. However, because of the nonlinear optical loss associated with two photon absorption (TPA) induced free carrier absorption (FCA) until now lasing has been limited to pulsed operation. Here we demonstrate a continuous wave silicon Raman laser. Specifically, we show that TPA induced FCA in silicon can be significantly reduced by introducing a reverse biased p i n diode embedded in a silicon waveguide. The laser cavity is formed by coating the facets of the silicon waveguide with multilayer dielectric films. We have demonstrated stable single mode laser output with side mode suppression of over 55 dB and linewidth of less than 80 MHz. The lasing threshold depends on the p i n reverse bias voltage and the laser wavelength can be tuned by adjusting the wavelength of the pump laser. The demonstration of a continuous wave silicon laser represents a significant milestone for silicon based optoelectronic devices.", "author_names": [ "Haisheng Rong", "Richard Jones", "Ansheng Liu", "Oded Cohen", "Dani Hak", "Alexander W Fang", "Mario Paniccia" ], "corpus_id": 4429297, "doc_id": "4429297", "n_citations": 1189, "n_key_citations": 14, "score": 0, "title": "A continuous wave Raman silicon laser", "venue": "Nature", "year": 2005 }, { "abstract": "We review the recent developments in the area of optical fiber grating sensors, including quasi distributed strain sensing using Bragg gratings, systems based on chirped gratings, intragrating sensing concepts, long period based grating sensors, fiber grating laser based systems, and interferometric sensor systems based on grating reflectors.", "author_names": [ "Alan D Kersey", "Michael A Davis", "Heather J Patrick", "Michel Joseph Leblanc", "Kee P Koo", "Charles G Askins", "Martin A Putnam", "E Joseph Friebele" ], "corpus_id": 5895223, "doc_id": "5895223", "n_citations": 3350, "n_key_citations": 93, "score": 0, "title": "Fiber grating sensors", "venue": "", "year": 1997 }, { "abstract": "Tunable semiconductor lasers have been listed in numerous critical technology lists for future optical communication and sensing systems. This paper summarizes a tutorial that was given at OFC '03. It includes some discussion of why tunable lasers might be beneficial, an outline of basic tuning mechanisms, some examples of tunable lasers that have been commercialized, and a discussion of control techniques. More extensive data is given for the widely tunable sampled grating distributed Bragg reflector (SGDBR) type of laser, including data for such lasers integrated monolithically with modulators to form complete transmitter front ends. A summary of reliability data for the SGDBR laser is also given. It is concluded that tunable lasers can reduce operational costs, that full band tunability is desirable for many applications, that monolithic integration offers the most potential for reducing size, weight, power and cost, and that sufficient reliability for system insertion has been demonstrated.", "author_names": [ "Larry A Coldren", "Gregory A Fish", "Yuliya Akulova", "Jonathon S Barton", "Linda Johansson", "Christopher W Coldren" ], "corpus_id": 19642982, "doc_id": "19642982", "n_citations": 300, "n_key_citations": 7, "score": 0, "title": "Tunable semiconductor lasers: a tutorial", "venue": "Journal of Lightwave Technology", "year": 2004 }, { "abstract": "A sequence of partially reflective slots etched into an active ridge waveguide of a 1.5 mum laser structure is found to provide sufficient reflection for lasing. Mirrors based on these reflectors have strong spectral dependence. Two such active mirrors together with an active central section are combined in a Vernier configuration to demonstrate a tunable laser exhibiting 11 discrete modes over a 30 nm tuning range with mode spacing around 400 GHz and side mode suppression ratio larger than 30 dB. The individual modes can be continuously tuned by up to 1.1 nm by carrier injection and by over 2 nm using thermal effects. These mirrors are suitable as a platform for integration of other optical functions with the laser. This is demonstrated by monolithically integrating a semiconductor optical amplifier with the laser resulting in a maximum channel power of 14.2 dBm from the discrete modes.", "author_names": [ "Diarmuid C Byrne", "J P Engelstaedter", "Wei-hua Guo", "Qiaoyin Lu", "Brian Corbett", "Brendan Roycroft", "James O'Callaghan", "Frank H Peters", "John F Donegan" ], "corpus_id": 30212308, "doc_id": "30212308", "n_citations": 59, "n_key_citations": 0, "score": 1, "title": "Discretely Tunable Semiconductor Lasers Suitable for Photonic Integration", "venue": "IEEE Journal of Selected Topics in Quantum Electronics", "year": 2009 }, { "abstract": "We report on a widely tunable transmitter based on a sampled grating distributed Bragg reflector (SG DBR) laser monolithically integrated with a semiconductor optical amplifier (SOA) and an electroabsorption (EA) modulator. Modulated time averaged powers in excess of 5 dBm, RF extinction ratios >10 dB, and error free transmission at 2.5 Gb/s for 350 km of standard single mode fiber have been demonstrated across a 40 nm tuning range. In CW mode of operation, the module meets all long haul system requirements for externally modulated laser sources: stability, power >10 mW) RIN 100 yr for output wavelength stability and power across all channels.", "author_names": [ "Yuliya Akulova", "Gregory A Fish", "Ping-Chiek Koh", "Clint L Schow", "Peter Kozodoy", "A Dahl", "Shigeru Nakagawa", "M C Larson", "M P Mack", "Timothy Andrew Strand", "Christopher W Coldren", "Eric R Hegblom", "Steven Penniman", "Torsten Wipiejewski", "Larry A Coldren" ], "corpus_id": 122810842, "doc_id": "122810842", "n_citations": 125, "n_key_citations": 11, "score": 0, "title": "Widely tunable electroabsorption modulated sampled grating DBR laser transmitter", "venue": "", "year": 2002 }, { "abstract": "Continuous wave operation of quantum cascade lasers is reported up to a temperature of 312 kelvin. The devices were fabricated as buried heterostructure lasers with high reflection coatings on both laser facets, resulting in continuous wave operation with optical output power ranging from 17 milliwatts at 292 kelvin to 3 milliwatts at 312 kelvin, at an emission wavelength of 9.1 micrometers. The results demonstrate the potential of quantum cascade lasers as continuous wave mid infrared light sources for high resolution spectroscopy, chemical sensing applications, and free space optical communication systems.", "author_names": [ "Mattias Beck", "Daniel Hofstetter", "Thierry Aellen", "Jerome Faist", "Ursula Oesterle", "Marc Ilegems", "Emilio Gini", "Hans Melchior" ], "corpus_id": 2073727, "doc_id": "2073727", "n_citations": 743, "n_key_citations": 24, "score": 0, "title": "Continuous Wave Operation of a Mid Infrared Semiconductor Laser at Room Temperature", "venue": "Science", "year": 2001 }, { "abstract": "Influences on the semiconductor laser properties of external optical feedback, i.e. return of a portion of the laser output from a reflector external to the laser cavity, have been examined. Experimental observations with a single mode laser is presented with analysis based on a compound cavity laser model, which has been found to explain essential features of the experimental results. In particular, it has been demonstrated that a laser with external feedback can be multistable and show hysteresis phenomena, analogous to those of non linear Fabry Perot resonator. It has also been shown that the dynamic properties of injection lasers are significantly affected by external feedback, depending on interference conditions between returned light and the field inside the laser diode.", "author_names": [ "R S Lang", "Kohroh Kobayashi" ], "corpus_id": 122897739, "doc_id": "122897739", "n_citations": 2214, "n_key_citations": 81, "score": 0, "title": "External optical feedback effects on semiconductor injection laser properties", "venue": "", "year": 1980 }, { "abstract": "In this paper, we describe the spectral characteristics that can be achieved in fiber reflection (Bragg) and transmission gratings. Both principles for understanding and tools for designing fiber gratings are emphasized. Examples are given to illustrate the wide variety of optical properties that are possible in fiber gratings. The types of gratings considered include uniform, apodized, chirped, discrete phase shifted, and superstructure gratings; short period and long period gratings; symmetric and tilted gratings; and cladding mode and radiation mode coupling gratings.", "author_names": [ "Turan Erdogan" ], "corpus_id": 120438068, "doc_id": "120438068", "n_citations": 2945, "n_key_citations": 204, "score": 0, "title": "Fiber grating spectra", "venue": "", "year": 1997 }, { "abstract": "The ability to tune the frequency of an oscillator is of critical importance and is a fundamental building block for many systems, be they mechanical or electronic1,2. However, this very important function is still highly inadequate in optical oscillators, particularly in semiconductor laser diodes3,4. The limitations in tuning a laser frequency (or wavelength) include the tuning range and the speed of tuning, which is typically milliseconds or slower. In addition, the tuning is often not continuous and may require complex synchronization of several electrical control signals. In this Letter, we present a new tunable laser structure with a lightweight nanoelectromechanical mirror based on a single layer, high contrast subwavelength grating. The high contrast subwavelength grating reflector enables a drastic reduction of the mirror mass, which increases the mechanical resonant frequency and hence tuning speed5. This allows for a wavelength tunable light source with potential switching speeds of the order of tens of nanoseconds and suggests various new areas of practical application, such as bio or chemical sensing6,7,8, chip scale atomic clocks9 and projection displays10,11.", "author_names": [ "Michael C Y Huang", "Ye Zhou", "Connie J Chang-Hasnain" ], "corpus_id": 3780310, "doc_id": "3780310", "n_citations": 218, "n_key_citations": 5, "score": 0, "title": "A nanoelectromechanical tunable laser", "venue": "", "year": 2008 } ]

[ { "abstract": "A central issue in computer vision is the problem of signal to symbol transformation. In the case of texture, which is an important visual cue, this problem has hitherto received very little attention. This book presents a solution to the signal to symbol transformation problem for texture. The symbolic de scription scheme consists of a novel taxonomy for textures, and is based on appropriate mathematical models for different kinds of texture. The taxonomy classifies textures into the broad classes of disordered, strongly ordered, weakly ordered and compositional. Disordered textures are described by statistical mea sures, strongly ordered textures by the placement of primitives, and weakly ordered textures by an orientation field. Compositional textures are created from these three classes of texture by using certain rules of composition. The unifying theme of this book is to provide standardized symbolic descriptions that serve as a descriptive vocabulary for textures. The algorithms developed in the book have been applied to a wide variety of textured images arising in semiconductor wafer inspection, flow visualization and lumber processing. The taxonomy for texture can serve as a scheme for the identification and description of surface flaws and defects occurring in a wide range of practical applications.", "author_names": [ "A Ravishankar Rao" ], "corpus_id": 34689429, "doc_id": "34689429", "n_citations": 432, "n_key_citations": 24, "score": 1, "title": "A Taxonomy for Texture Description and Identification", "venue": "Springer Series in Perception Engineering", "year": 1990 }, { "abstract": "Abstract The genus Typopeltis Pocock, 1894 is poorly known regarding its systematics, natural history, and distribution, despite important taxonomic advances during the 1990s. Currently, only 13 species are known from East Asia, including areas in south China, Japan, Vietnam, Laos, Thailand, and Taiwan. In this work, we describe and illustrate a new species of Typopeltis from Vietnam and provide a new description for the male of T.guangxiensis Haupt Song, 1996. Additionally, we describe and illustrate the female gonopod of T.guangxiensis for the first time and propose a new homology hypothesis for the male gonopod parts. The male of T.laurentianussp. n. is characterized by the unique patellar apophysis that presents a smooth texture and no spines. Typopeltislaurentianussp. n. is the third species of this genus to be described from Vietnam.", "author_names": [ "Gabriel Seraphim", "Alessandro P L Giupponi", "Gustavo Silva de Miranda" ], "corpus_id": 173990067, "doc_id": "173990067", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Taxonomy of the thelyphonid genus Typopeltis Pocock, 1894, including homology proposals for the male gonopod structures (Arachnida, Thelyphonida, Typopeltinae)", "venue": "ZooKeys", "year": 2019 }, { "abstract": "Globuligerina glinskikhae nov. sp. Gradstein Waskowska and Globuligerina waskowskae nov. sp. Gradstein are new species of Jurassic planktonic foraminifera from the Middle Jurassic of Dagestan and Poland. G. glinskikhae nov. sp. with its remarkable 'protoglobigerine' test may be an early evolutionary offshoot of Globuligerina oxfordiana (Grigelis) It may be an index taxon for upper Bajocian through Bathonian strata in Eastern Europe and Southwest Asia, and might be recognizable also in thin sections. We consider G. waskowskae nov. sp. to be a possible forerunner of Conoglobigerina helvetojurassica (Haeusler) the first planktonic foraminiferal species with a reticulate wall texture. Currently, is only known from Poland. In some localities, specimens of G. oxfordiana and of G. glinskikhae nov. sp. posses an additional apertural opening, often lacking a rim; its function is enigmatic. The postulated lineage from Jurassic Globuligerina balakhmatovae (Morozova) to Cretaceous Clavihedbergella eocretacea Neagu is refined with the description of Petaloglobigerina simmonsi nov. gen. nov. sp. Gradstein from the Kimmeridgian of Portugal. The evolutionary transition from G. balakhmatovae to P. simmonsi occurs by means of the ontogenic development of a petaloid test, with a pronounced flattening of the whorl with ovate chambers, the last ones often offset and twisted. Jurassic planktonic foraminifera, now known to consist of three genera and 12+ species underwent long periods of stasis, interrupted by late Bajocian, mid Oxfordian and early Kimmeridgian evolution. The three 'stasis and root' taxa G. oxfordiana G. bathoniana and G. balakhmat ovae are geographically widespread in lower to mid palaeo latitudes, and stratigraphically long ranging within the Middle and Late Jurassic. Modern digital microscopes, with co axial and side LED lighting and excellent image stacking software are important tools in the study of Jurassic planktonic foraminifera, and fast and cost effective communication tools in modern micropalaeontology.", "author_names": [ "F M Gradstein", "Anna Waskowska" ], "corpus_id": 231202891, "doc_id": "231202891", "n_citations": 3, "n_key_citations": 1, "score": 0, "title": "New insights into the taxonomy and evolution of Jurassic planktonic foraminifera", "venue": "Swiss Journal of Palaeontology", "year": 2021 }, { "abstract": "Texture is generally recognized as being fundamental to perception. A taxonomy of problems encountered within the context of texture analysis could be that of classification/discrimination, description, and segmentation. In this paper we suggest a novel artificial neural network (ANN) architecture for features extraction and texture recognition. There is evidence which suggests that the analysis of stimulus by visual system might involve a set of quasi independent mechanisms called channels which could be conveniently characterized in the spatial frequency domain. In our model we use an FT feature space with angular and radial bins that characterize spatial domain filters to extract features. The extracted features are then used as input for the recognition stage. In order to evaluate the 2 D FT coefficients we use the Radon transform. The usage of the Radon transform simplifies the ANN model significantly. We suggest an electronic implementation of the ANN model for feature extraction, using a Connected Network Adaptive ProcessorS (CNAPS) chip designed by Adaptive Solutions Inc. We also develop software to simulate the ANN model with the Radon transform. We use a three stage back propagation network as a classifier. We have used ten different texture patterns to test our ANN model.", "author_names": [ "Arun D Kulkarni", "P Byars" ], "corpus_id": 63722890, "doc_id": "63722890", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Artificial neural network models for texture classification via the radon transform", "venue": "Other Conferences", "year": 1992 }, { "abstract": "Texture is generally recognized as being fundamental to perception. A taxonomy of problems encountered within the context of texture analysis could be that of classification /discrimination, description, and segmentation. In this paper we suggest a novel artificial neural network (ANN) architecture for feature extraction and texture recognition. There is evidence which suggests that the analysis of stimulus by visual system might involve a set of quasiindependent mechanisms called channels which could be conveniently characterized in the spatial frequency domain. In our model we use an IT feature space with angular and radial bins that characterize spatial domain filters to extract features. The extracted features are then used as input for the recognition stage. In order to evaluate the 2 D FT coefficients we use the Radon transform. The usage of the Radon trmsforrn simplifies ~he ANN model significantly. We have developed software to simulate the ANN model with the Radon transform. We used a three stage backpropagation network as a classifier. We used ten different texture patterns to test our ANN model. The results are presented in the paper.", "author_names": [ "Arun D Kulkarni", "P Byars" ], "corpus_id": 18002238, "doc_id": "18002238", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Artificial neural network models for texture classification via: the Radon transform", "venue": "SAC '92", "year": 1992 }, { "abstract": "Parasitological research today focused on studying protozoan parasites infecting fish especially myxosporidian and microsporidian parasites which cause adverse effects on the fish health causing high losses in fish production. Also the presence of Heavy infections with muscle invading species destroy the texture of the fish flesh making it unmarketable. Morphological description of these parasites help in the exact determination of their taxonomy which may aid with the molecular tools in the development of anti substances against these parasites. The present book described some of these parasites including two myxosporidian and three microsporidian species infecting flesh of four of the most economically important marine fishes of the Red Sea in Egypt. The study described the different developmental stages of these parasites which undergoes its maturation within fish flesh until its progressive development into the infective spores which are the most dangerous and infective part of the cycle.", "author_names": [ "Kareem Morsy", "Fathy Abdel-Ghaffar", "A -R Bashtar" ], "corpus_id": 90945085, "doc_id": "90945085", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Myxosporidiosis and Microsporidiosis of Fish", "venue": "", "year": 2013 }, { "abstract": "The investigated area is located to the east of the Nile Delta; it is bounded by latitudes 30deg 11' 15\" 30deg 14' 10\" N and longitudes 31deg 22' 05\" 31deg 24' 20\" E. According to period of irrigated by sewage effluents the soils of the area were divided into four grades. These include i) non irrigated and barren, ii) irrigated for (24 years) iii) irrigated for (49 years) and iv) irrigated for 82 years until 2009 and after this changed to irrigated by ground water. Four soil profiles were taken to represent the soils of the area. Morphological description and soil sampling were conducted during the field work. The soil properties including texture, depth, organic matter (OM) EC, CaCO3, pH, CEC, and ESP have been determined. The soils were classified as: Typic Torripsamments and Typic Torriorthents according to the American soil taxonomy. The soil capability classes ranged between (2) good and (5) very poor. The soil suitability ranged between S1 and S3. The soils of the area are suitable for field crops (Wheat, Barley, Faba bean, Sugar beat, Sun flower, Maize, Soya bean, Peanut, Cotton, Sugar Cane) vegetable (Tomato, Pepper, Watermelon, Alfalfa, Sorghum) and fruit (Citrus, Grape, Olive, Apple, Pear, Figs, Date palm) The soils are in general not suitable for Cabbage, Onion, Rice and Banana.", "author_names": [ "Masato Oda", "A A Abd El-Hady", "Wagdy A Kawi", "Ramadan R Ali" ], "corpus_id": 210308011, "doc_id": "210308011", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "STUDY AND EVALUATE EL GABAL EL ASFAR SOILS WHICH IRRIGATED BY SEWAGE SLUDGE", "venue": "", "year": 2013 }, { "abstract": "One of the promising areas for the horizontal expansion in west Azerbaijan (Iran) is the Souma area. Peach suitability calculated on the basis of the proposed computer program \"MicroLEIS DSS\" and presented as a soil suitability map has been integrated with GIS tools. Nine benchmark soil series constituents comprising 35 soil profiles have been selected to represent the variation in soils of the studied area. According to the morphological description, physical and chemical properties and USDA Soil Taxonomy, the soils can be classified as Entisols and Inceptisols. Useful depth, texture, drainage, carbonate, salinity, sodium saturation and profile development were selected as limitation factors for peach development. For perennial crops (peach) soil reference sections are between 0 and 100 cm in depth, or between 0 cm and the limit of useful depth when the latter is between 0 and 100 cm. Following a semi quantitative procedure and according to the generalization level set up for each soil diagnostic criterion, the area under investigation has been divided into four relative suitability classes. Results showed that texture and drainage are the most important limitation factors in 2266 ha and 66 ha respectively of the study area. Peach garden development can be recommended for 1824 ha of the studied area with special reference to sustainable agriculture achievement.", "author_names": [ "A A Jafarzadeh", "Farzin Shahbazi", "R J Gilkes", "Nattaporn Prakongkep" ], "corpus_id": 131565763, "doc_id": "131565763", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Suitability of peach in Souma area (Iran) using Almagra model.", "venue": "", "year": 2010 }, { "abstract": "Human activities often alter soils found in urban areas. These alterations affect their environmental functions and potential for use. However, soils from urban areas in Brazil have not been surveyed and identified, which can pose a technical problem for the development of the city. Considering the importance of urban environments and their soils, this study aimed to evaluate the environmental and morphological characteristics and the physical properties of urban soils in Santa Maria, Rio Grande do Sul, Brazil. The purpose was then to organize a protocol for describing urban soils and to identify diagnostic qualifiers to subsidize establishment of an order that allows proper classification of these soils in the Brazilian Soil Classification System. The protocol containing general and environmental notes and morphological notes and qualifiers was organized based on the experience of this study and the relevant literature. The environmental, morphological, and physical analyses carried out supported interpretation of the urban soils of Santa Maria, their classification in the World Reference Base for Soil Resources system, and identification of diagnostic qualifiers proposed for the Brazilian Soil Classification System. The protocol tested in this study was adequate for data collection in the field. Soils had high variation in layer thickness, particle size composition, color, bulk density, saturated hydraulic conductivity, penetration resistance, stoniness, and the presence of artifacts. Considering the establishment of a Brazilian taxonomy for urban soils, the field data led to the proposal for new qualifiers, such as Saprolitic (residual saprolite material) Impervic (sealed/impermeable layer) Multigranic (layers with contrasting textures) Stonic (layers with stoniness) and Saprorockic (layers constituted of transported saprolite) which can be used as diagnostic attributes in the Brazilian Soil Classification System and even contribute to improvement of the order of Technosols in the World Reference Base For Soil Resources system.", "author_names": [ "Jessica da Costa", "Fabricio de Araujo Pedron", "Ricardo Simao Diniz Dalmolin", "Ricardo Bergamo Schenato" ], "corpus_id": 196988335, "doc_id": "196988335", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Field Description and Identification of Diagnostic Qualifiers for Urban Soils in Brazil", "venue": "", "year": 2019 }, { "abstract": "Diverse plant species of the earth constitute the fundamental source of crude drugs and the diversified botanical species comprising of non seed and seed plants, for the convenience of study, may be classified following artificial, natural, or phylogenetic system. None but the phylogenetic system put emphasis on the evolutionary relationship among different taxa of plants (e.g. Engler and Prantl, Bessey, Hutchinson, Takhtasan, Cronquists systems) Linnaeus artificial system is of little importance today, but his binomial system of nomenclature of organisms is now widely practiced. The various taxa or ranks used in plant classification following ICBN in ascending hierarchy are Species, Genus, Family, Order, Class, Subdivision, Division, and Kingdom. The naming of plants and understanding of the species' relationship to other species is essential for botanists, pharmacognosists, phytochemists, and other professionals working in the field of plant science. Taxonomic or botanical identity of medicinal plants is a fundamental step in the scientific study for their effective therapeutic use as well as forms the basis of correct identification and authentication of crude drugs from adulterants. Documentation requires an accurately identified vouchered plant sample of a recognized herbarium. Secondary metabolites and pigments (e.g. alkaloids, phenolics, terpenes, anthocyanins, carotenoids) constitute the active therapeutic principles of crude drugs (e.g. inulin of dahlia root, quinine of cinchona bark, morphine and codeine of poppy latex, and digoxin of foxglove) Similarly, therapeutically important other metabolites like agar, alginic acid, floridean starch, iodine, potash are derived from algae; ergoline alkaloids, lysergic acid derivatives, vitamin B complex and different antibiotics from fungi; and essential oils (e.g. alphapinene and borneol) balsams, flavonoids, condensed tannins, lignans, etc. are widely present in the members of Pinaceae. Important plant families of angiosperms to which a large number of medicinal plants belong are Apiaceae, Apocinaceae, Asteraceae, Boraginaceae, Brassicaceae, Caryophyllaceae, Cesalpinaceae, Cucurbitaceae, Fabaceae, Lamiaceae, Malvaceae, Mimosaceae, Papaveraceae, Phytolaccaceae, Ranunculaceae, Roseaceae, Rutaceae, Solanaceae, Scrophulariceae and Verbenaceae of dicot and Liliaceae, Orchidaceae, and Zingiberaceae of monocot. Systematics is an important tool in pharmacognostical practice and may be helpful to guess the probable presence of secondary metabolites in different taxa; for example, many members of Apiceae contain essential oils, presence of highly aromatic compounds in the members of Lamiaceae, alkaloids in Solanaceae, Papaveraceae and tannins in members of Sapindaceae. Structural description of a drug plant at morphological (macroscopic) and anatomical (microscopic) levels as used in the pharmacopoeial texts of crude drugs is important for its botanical identity, quality of herbal preparation, and pharmacognostical standardization. Roots, stems, and leaves as well as flowers and fruits are the basic morphological organs of higher plants. Modification of some of these organs are also known, e.g. stem modified into underground (rhizome, tuber, bulb, corm, etc. subaerial (runner, stolon, offset, sucker, etc. and aerial (tendril, spine, phylloclade, cladode, bulbil) stems to take over different functions. Shape, size, and forms as well as color, texture, fracture aspects, and characteristics of the cut surface of these major organs and associated other minor structures are also taken into consideration. Morphological identity is very often needed to be supplemented by anatomical characters because many different closely related plants look similar in their external appearance and comminuted drugs loss their morphological identity. The basic unit of plant body is a cell, and organized cells develop tissue and specific organs like root, stem, leaf, flower, fruit, seed of the organized drugs. A clear understanding of the structure, organization, and contents of these cells and tissues is important for meaningful study and correct botanical identification of crude drugs. Cells vary in size (1 100 mm) and shape (spherical, oval, polygonal, rectangular, or elongated) Cell components are divisible into cell wall, protoplasm, and vacuole. A cell wall may contain lignin, cutin, suberin, mucilage, etc. in addition to cellulose. Cells with lignified walls are dead and characteristics of the mechanical and vascular tissues such as tracheids, fibers, sclereids, and vessels. Plasma membrane, cytoplasm, and nucleus constitute the protoplasm. Cytoplasm is a translucent mass of colloidal substances, composed of water, protein, carbohydrate, lipoids, and various inorganic substances. The waste or ergastic products of metabolism occur as cell contents in a number of plant drugs include solid substances (e.g. calcium oxalate and calcium carbonate crystals, silica) and substances in solution in the cell sap (e.g. alkaloids, glycosides, volatile oils, resins, tannins, gums, mucilage) Calcium oxalate crystals are of considerable diagnostic importance of plant drugs (e.g. prisms of calcium oxalate occur in Senna, Liquorice, Cascara, Rauvolfia) raphides (e.g. bundles of needles in Coco yam, Squill) single acicular crystals (in Cinnamon, Gentian, Ipecacuanha, microsphenoidal, etc. or sandy crystals (e.g. in Belladonna) Calcium oxalate crystals are also useful in distinguishing between the drugs of the same family. Calcium oxalate crystals are also useful in the detection of adulterants (e.g. presence of Phytolacca leaves in Belladonna samples can be detected by the acicular crystals of Phytolacca) These crystals are found embedded or incrusted in the cell walls of certain plants (e.g. calcium carbonate crystals, cystoliths, occur in many plants of the families: Urticaceae, Moraceae, Cannabinaceae, Acanthaceae, and also in Combretaceae and Boraginaceae) The occurrence of cystolith hairs is an important criterion for the identification of marijuana leaf fragments. Alkaloids and glycosides are important therapeutically active chemical substances, which remain in solution in the cell sap of many plant drugs. Their presence can only be detected by Dragendorff or Mayer's reagent for alkaloids and Borntrager's reagent for anthraquinone glycosides. The internal structural knowledge is applicable for the identification of organized crude drugs, while the botanical identity of unorganized drugs should be determined by chemical analysis.", "author_names": [ "A N M Alamgir" ], "corpus_id": 90488420, "doc_id": "90488420", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Pharmacognostical Botany: Classification of Medicinal and Aromatic Plants (MAPs) Botanical Taxonomy, Morphology, and Anatomy of Drug Plants", "venue": "", "year": 2017 } ]

[ { "abstract": "Technology computer aided design (TCAD) semiconductor device simulators solve partial differential equations (PDE) using the finite volume method (FVM) or related methods. While this approach has been in use over several decades, its methods continue to be extended, and are still applicable for investigating novel devices. In this paper, we present an element edge based (EEB) FVM discretization approach suitable for capturing vector field effects. Drawing from a 2D approach in the literature, we have extended this method to 3D. We implemented this method in a TCAD semiconductor device simulator, which uses a generalized PDE (GPDE) approach to simulate de vices with the FVM. We describe how our EEB method is compatible with the GPDE approach, allowing the modeling of vector effects using scripting. This method is applied to solve polarization effects in a 3D ferro capacitor, and a 2D ferroelectric field effect transistor. An example for field dependent mobility in a 3D MOSFET is also presented.", "author_names": [], "corpus_id": 238153151, "doc_id": "238153151", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Element Edge Based Discretization for TCAD Device Simulation", "venue": "IEEE Transactions on Electron Devices", "year": 2021 }, { "abstract": "CMOS scaling became popular among researchers and the semiconductor industry since it provides many advantages like faster speed, higher performance, and increased integration density on a chip. Despite the above advantages, short channel effects are a major concern for planar devices at lower technology nodes which led to the development of multiple gate FETs (MugFET) such as Nanosheet FETs (NSFET) Nanowire FET (NWFET) and FinFET as a replacement for planar MOSFETs. Among all these MugFETs, for sub 7nm technology node, NSFETs are a potential replacement of FinFET and NWFETs due to their high drive current and speed. However, the small channel area and doping profile make these MugFETs more susceptible to Process induced variation. In this thesis, some of these issues are discussed and solutions are proposed. The work presented in this thesis is done using Synopsys Sentaurus TCAD and all the characterization is done using Cascade manual prober along with Keysight B1500 parameter analyzer. In the initial part of the thesis, CMOS FETs are designed and simulated using Sentaurus TCAD to match Semiconductor Laboratory (SCL) CMOS 0.18mm device's physical design and electrical characteristics. Id Vgs of n and p type FETs are measured in linear as well as in the saturation region and finally calibrated using the Sentaurus TCAD model. SOI device's faster speed, resistance to latch up, and immunity against radiation make it preferable over conventional planar devices. PD SOI and FD SOI FETs are also designed to a specific 0.18um CMOS target using a calibrated TCAD model for radiation analysis. MugFETs with small channel area are subject to Line edge roughness (LER) due to process induced variation. LER can result in a high mismatch in FET's electrical characteristics. In this thesis, a 3 D LER model has been taken for the accurate analysis of mismatch in NS and NW FETs electrical characteristics. The mismatch performance of NSFET is investigated and reported for different NS widths. Also, SCE performance parameters, like DIBL (mV) and SS (mV/dec) sensitivity to LER are investigated in this chapter. Moreover, the Junctionless mode devices (JL) are preferred over Inversion mode (IM) devices for nanoscale FETs design due to their simple fabrication process, high drive current, and feasibility of doing short channel length design. However, JL FETs are more susceptible to process induced variation. This thesis also includes a study of matching the performance of inversion (INV) and junctionless (JL) NS/NW FETs devices for 3 D LER. Semiconductor devices are also being widely used in space for various applications, also affected by the presence of Cosmic rays consist of different particles such as heavy ions, neutrons, protons, electrons, alpha particles, and gamma rays. Among these cosmic ray particles, heavy ions cause a change in the state of memory element or temporary circuit failure due to instantaneous transient current spike in devices. In the next part of the thesis, heavy ion induced single event transient (SET) in bulk and SOI NSFET are discussed. Vertically stacked nanosheets are designed and simulated using the inbuilt heavy ion Sentaurus TCAD model. SET current in bulk and SOI NSFETs for different device dimensions are investigated and discussed in this thesis. Also, the effect of the different angles of ion incidence on SET performance is analyzed. SOI NSFETs show a distinct advantage over bulk devices for heavy ion SET. Further, different 3 D SOI MugFETs, such as FinFET, NSFET, and NWFET are simulated for SET due to heavy ion irradiation and compared. Finally, an empirical model is also presented in this thesis to predict the SET current with physical design parameters of MugFETs, and as well as the heavy ion model parameters. Physical design as well as heavy ion parameters, such as nanosheet fin width/ thickness, the diameter of a nanowire, linear energy transfer (LET) angle of incidence, and channel doping are incorporated to accurately predict SET due to heavy ion irradiation on these MugFETs.", "author_names": [], "corpus_id": 232401250, "doc_id": "232401250", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "TCAD Based Modelling of Line Edge Roughness and Radiation Effects in Advanced CMOS Devices", "venue": "", "year": 2021 }, { "abstract": "The scalable iterative solution of strongly coupled three dimensional incompressible resistive magnetohydrodynamics (MHD) equations is very challenging because disparate time scales arise from the electromagnetics, the hydrodynamics, as well as the coupling between these systems. This study considers a mixed finite element discretization of a dual saddle point formulation of the incompressible resistive MHD equations using a stable nodal (Q2/Q1) discretization for the hydrodynamics and a stable edge node discretization of a reduced form of the Maxwell equations. This paper presents new approximate block factorization preconditioners for this system which reduce the system to approximate Schur complement systems that can be solved using algebraic multilevel methods. These preconditioners include a new augmentation based approximation for the magnetic induction saddle point system as well as efficient approximations of the Schur complements that arise from the complex coupling between the Navier Stokes eq.", "author_names": [ "Edward G Phillips", "John N Shadid", "Eric C Cyr", "Howard C Elman", "Roger P Pawlowski" ], "corpus_id": 15570663, "doc_id": "15570663", "n_citations": 27, "n_key_citations": 5, "score": 0, "title": "Block Preconditioners for Stable Mixed Nodal and Edge finite element Representations of Incompressible Resistive MHD", "venue": "SIAM J. Sci. Comput.", "year": 2016 }, { "abstract": "Abstract A new recovery method of edge elements for Maxwell's equations is proposed to reduce the recovery problem into one dimensional settings by using the local symmetry projection. The recovered method is applied to both Nedelec interpolation and edge finite element approximation. Superconvergence results are established for both the postprocessed Nedelec interpolation and the recovered edge finite element approximation in a discrete norm. Numerical examples are presented to illustrate our theoretical analysis.", "author_names": [ "Chao Wu", "Yunqing Huang", "Nianyu Yi", "Jinyun Yuan" ], "corpus_id": 224886785, "doc_id": "224886785", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Superconvergent recovery of edge finite element approximation for Maxwell's equations", "venue": "", "year": 2020 }, { "abstract": "In order to couple external circuits to edge element discretized electromagnetic models, with full field equations, global constraints involving voltages or currents need to be enforced. There is no canonical way to impose a voltage or a current without additional modeling information on the distribution of field sources that rely on topological concepts. In this article, a fast solution of field sources within massive conductors in static and dynamic problems is proposed. Global basis functions, required to cope with non trivial coil topologies, are directly generated by an iterative solver rather than pre computing source fields, e.g. by tree cotree decomposition.", "author_names": [ "Federico Moro", "Lorenzo Codecasa" ], "corpus_id": 209460472, "doc_id": "209460472", "n_citations": 1, "n_key_citations": 1, "score": 0, "title": "Enforcing Lumped Parameter Excitations in Edge Element Formulations by Using a Fast Iterative Approach", "venue": "IEEE Transactions on Magnetics", "year": 2020 }, { "abstract": "The high speed and high efficient cutting is the future of the mechanical processing technology. The tool edge preparation prolongs the service life of the tool, elevates the machined surface quality and the cutting performance through modification of the cutting edge contour, micro topography and microstructure in the edge area. It is necessary to study the edge preparation mechanism to realize the importance of the high speed and high efficiency cutting. The mathematical model of the milling tool motion trajectory is built up using the edge preparation characteristics of the planetary motion. Based on the basic principle of the discrete element method and the Hertz contact theory, the simulation model of the tool edge preparation process is set up through the discrete element software EDEM. The effects of the speed, the preparation time, the abrasive mesh, the abrasive ratio, the rotation direction on the abrasive state, the abrasive velocity, the cumulated energy, the wear and the action force are investigated. In this paper, the basis for the edge preparation optimization is provided and the importance of the high speed and high efficiency machining is highlighted.", "author_names": [ "Xuefeng Zhao", "Pengfei Zheng", "Lin He", "Meng Tao" ], "corpus_id": 216399432, "doc_id": "216399432", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Cutting edge preparation using the discrete element software EDEM", "venue": "", "year": 2020 }, { "abstract": "ABSTRACT The seismic assessment of archaeological heritages is studied by means of 2D numerical analysis with Discrete Element Method (DEM) The proposed approach is based on a refined discretization that reproduces the effective block masonry pattern and on a routine for carrying out seismic analysis according to either quasi static or dynamic approaches. The applicability of the DEM for the analysis of archaeological heritages is discussed referring to the case studies of the south east edge of the external wall of the Colosseum that was restored by Stern in 1807, and the arcades of the Claudio Aqueduct in Rome. The analyses based on DEM provide a reliable estimate of the seismic capacity and a refined representation of the expected failure mode, while also contributing to the design of appropriate strengthening measures. The approach is finally validated through comparison between the outcome of the numerical simulation and the survey of the existing crack pattern of the monuments.", "author_names": [ "Anna Mordanova", "Gianmarco de Felice" ], "corpus_id": 115533103, "doc_id": "115533103", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Seismic Assessment of Archaeological Heritage Using Discrete Element Method", "venue": "", "year": 2020 }, { "abstract": "Abstract We in this study present a mixed solid shell finite element formulation for laminated shell analysis. With the commonly adopted truncations applied to the strain components and the Jacobian determinant, a generalized stiffness matrix is established. Discrete shear gap (DSG) technique together with assumed natural strain (ANS) method is employed in order to alleviate shear locking and trapezoidal locking. Stiffness matrix formulation is analytically calculated based on the edge based cell backgrounds, which result in simple and efficient computation. The proposed formulation does not require using cross diagonal meshes, which can be an obstacle for several existing three node degenerated shell elements. This aspect makes the present method much more appealing than others through examples tested. Numerical validations show that the present method performs well for both structured and unstructured triangular meshes.", "author_names": [ "Leonardo Leonetti", "Hung Nguyen-Xuan" ], "corpus_id": 139961444, "doc_id": "139961444", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "A mixed edge based smoothed solid shell finite element method (MES FEM) for laminated shell structures", "venue": "", "year": 2019 }, { "abstract": "The aim of this paper is to develop a virtual element method for the two dimensional Steklov eigenvalue problem. We propose a discretization by means of the virtual elements presented in [L. Beirao da Veiga et al. Basic principles of virtual element methods, Math. Models Methods Appl. Sci.23 (2013) 199 214] Under standard assumptions on the computational domain, we establish that the resulting scheme provides a correct approximation of the spectrum and prove optimal order error estimates for the eigenfunctions and a double order for the eigenvalues. We also prove higher order error estimates for the computation of the eigensolutions on the boundary, which in some Steklov problems (computing sloshing modes, for instance) provides the quantity of main interest (the free surface of the liquid) Finally, we report some numerical tests supporting the theoretical results.", "author_names": [ "Felipe Lepe", "David Mora", "Gonzalo Rivera", "Ivan G Velasquez" ], "corpus_id": 121492213, "doc_id": "121492213", "n_citations": 87, "n_key_citations": 4, "score": 0, "title": "A virtual element method for the Steklov eigenvalue problem allowing small edges", "venue": "ArXiv", "year": 2020 }, { "abstract": "MFEM is an open source, lightweight, flexible and scalable C+ library for modular finite element methods that features arbitrary high order finite element meshes and spaces, support for a wide variety of discretization approaches and emphasis on usability, portability, and high performance computing efficiency. MFEM's goal is to provide application scientists with access to cutting edge algorithms for high order finite element meshing, discretizations and linear solvers, while enabling researchers to quickly and easily develop and test new algorithms in very general, fully unstructured, high order, parallel and GPU accelerated settings. In this paper we describe the underlying algorithms and finite element abstractions provided by MFEM, discuss the software implementation, and illustrate various applications of the library.", "author_names": [ "Robert W Anderson", "Julian Andrej", "Andrew T Barker", "Jamie A Bramwell", "Sylvain Camier", "Jakub Cerveny", "Veselin A Dobrev", "Yohann Dudouit", "Aaron C Fisher", "Tzanio V Kolev", "Will Pazner", "Mark Stowell", "Vladimir Z Tomov", "Johann P S Dahm", "David Medina", "Stefano Zampini" ], "corpus_id": 208202464, "doc_id": "208202464", "n_citations": 62, "n_key_citations": 5, "score": 0, "title": "MFEM: a modular finite element methods library", "venue": "Comput. Math. Appl.", "year": 2021 } ]

[ { "abstract": "We demonstrate an all fiber widely wavelength tunable thulium doped fiber laser (TDFL) mode locked by a semiconductor saturable absorber mirror (SESAM) The tuning range spans 121 nm, from 1862 nm to 1983 nm. The central wavelength is tuned by a grating based tunable filter in the ring laser cavity. To the best of our knowledge, this is so far the most widely wavelength tunable TDFL mode locked by SESAM.", "author_names": [ "Zhuo Xu", "Zhiyuan Dou", "Jing Hou", "Xiaojun Xu" ], "corpus_id": 24299660, "doc_id": "24299660", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "All fiber wavelength tunable Tm doped fiber laser mode locked by SESAM with 120 nm tuning range.", "venue": "Applied optics", "year": 2017 }, { "abstract": "We report a semiconductor saturable absorber mirror <inline formula> <tex math notation=\"LaTeX\"$Q$ /tex math>/inline formula> switched holmium (Ho<sup>3+/sup> doped ZrF₄ BaF₂ LaF₃ AlF₃ NaF fiber laser operating at ~1190 nm in a linear cavity. Stable <inline formula> <tex math notation=\"LaTeX\"$Q$ /tex math>/inline formula> switched operation was established at a threshold pump power of 92.8 mW with a repetition rate of 26.1 kHz and a pulsewidth of <inline formula> <tex math notation=\"LaTeX\"$4~\\mu \\text{s} /tex math>/inline formula> The repetition rate increased and the pulsewidth decreased with an increasing pump power. When the pump power was increased to 830 mW, 800 ns <inline formula> <tex math notation=\"LaTeX\"$Q$ /tex math>/inline formula> switched pulses with a pulse energy of <inline formula> <tex math notation=\"LaTeX\"$0.18~\\mu \\text{J} /tex math>/inline formula> at a repetition rate of 170 kHz were generated.", "author_names": [ "Yuchen Wang", "Xiushan Zhu", "Chuanxiang Sheng", "Lei Li", "Qian Chen", "Jie Zong", "Kort Wiersma", "Arturo Chavez-Pirson", "Robert A Norwood", "Nasser Peyghambarian" ], "corpus_id": 21925497, "doc_id": "21925497", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "SESAM $Q$ Switched Ho3+ Doped ZBLAN Fiber Laser at 1190 nm", "venue": "IEEE Photonics Technology Letters", "year": 2017 }, { "abstract": "We present a stable Yb doped SESAM mode locked fiber laser operating in the similariton regime. 4.8 ps pulses were obtained at the central wavelength of 1030 nm and the de chirped pulse duration was 83 fs.", "author_names": [ "Huibo Wang", "Hainian Han", "Yang Xie", "Yang Yu", "Hao Teng", "Shaobo Fang", "Jiangfeng Zhu", "Zhiyi Wei" ], "corpus_id": 139934237, "doc_id": "139934237", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Stable SESAM mode locked Yb fiber laser in the similariton regime", "venue": "", "year": 2017 }, { "abstract": "The rising demand in ultrafast radiation sources has boosted the search for high power and high stability mode locked fiber lasers, particularly at telecom wavelengths. In this work, we demonstrate the first ultrafast mode locked fiber laser relying on InN as saturable absorber, centered at 1.5mm. The saturable absorber consists of a 1 mm thick InN grown on a GaN on sapphire template deposited by molecular beam epitaxy [1] with a 250 nm thick top layer of Al deposited by RF sputtering. This material presents a very high nonlinear optical response, with a saturation fluence of Fsat=490 mJ/cm2 and a large change in reflectance, of approximately the 100% [inset Fig. 1(a) It has been proved that the material can withstand extremely high fluences of 9000 mJ/cm2 without suffering optical damage.", "author_names": [ "Marco Jimenez-Rodriguez", "Francesca Gallazzi", "Juan Diego Ania-Castanon", "Eva Monroy", "Miguel Gonzalez-Herraez", "Fernando Bernabe Naranjo" ], "corpus_id": 41217501, "doc_id": "41217501", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Sub 200 fs mode locked fiber laser with InN based SESAM", "venue": "2017 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)", "year": 2017 }, { "abstract": "We demonstrate ultrafast harmonically mode locked fiber lasing in up to 6 km long rings at 1.56mm with InN SESAM. Fundamental mode locking with pulse width of 239fs, pulse energy of 155nJ and peak power of 650kW is achieved with a 1 km long cavity.", "author_names": [ "Francesca Gallazzi", "Marco Jimenez-Rodriguez", "Eva Monroy", "Pedro Corredera", "Miguel Gonzalez-Herraez", "Fernando Bernabe Naranjo", "Juan Diego Ania-Castanon" ], "corpus_id": 13830339, "doc_id": "13830339", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Sub 250 fs, 650 kW Peak Power Harmonic Mode Locked Fiber Laser with InN based SESAM", "venue": "2017 European Conference on Optical Communication (ECOC)", "year": 2017 }, { "abstract": "", "author_names": [ "Luo Jiang Luo Jiang", "Yang Song Yang Song", "Hao Qiang Hao Qiang", "Ceng He Ping Zeng Heping" ], "corpus_id": 125707439, "doc_id": "125707439", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Precise Locking the Repetition Rate of a SESAM Mode Locking All Polarization Maintaining Fiber Laser", "venue": "", "year": 2017 }, { "abstract": "Abstract We present a widely tunable all fiber mode locked laser based on semiconductor saturable absorber mirror (SESAM) with a linear cavity design. An easy to use tunable bandpass filter based on thin film cavity technology is employed to tune the wavelength. By tuning the filter and adjusting the polarization controller, mode locked operation can be achieved over the range of 1023 nm 1060 nm. With the polarization controller settled, mode locked operation can be preserved and the wavelength can be continuously tuned from 1030 nm to 1053 nm. At 1030 nm, the laser delivers 9.6 mw average output power with 15.4 ps 10.96 MHz pulses at fundamental mode locked operation.", "author_names": [ "Feng Zou", "Zhaokun Wang", "Ziwei Wang", "Yangbo Bai", "Qiurui Li", "Jun Zhou" ], "corpus_id": 125628557, "doc_id": "125628557", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Widely tunable all fiber SESAM mode locked Ytterbium laser with a linear cavity", "venue": "", "year": 2017 }, { "abstract": "In this letter, we present a passively mode locked Yb:CALGO oscillator pumped by a 1.2 W single mode fiber coupled laser diode. In semiconductor saturable absorber mirror (SESAM) mode locking regime, maximum output power of 385 mW with a laser slope efficiency of 40% has been achieved. The pulse duration of the mode locked pulse is 630 fs, and the full width at half maximum (FWHM) of the spectrum is measured as only about 2.7?nm. By finely tuning the laser cavity, the laser starts to work in the SESAM combined Kerr lens mode locking regime. Compared with SESAM mode locking only, a maximum reduction factor of 6.33 in pulse duration has been achieved by the combined mode locking mechanism. By optimizing the group delay dispersion (GDD) inside the laser cavity, the shortest pulse duration of 70 fs and FWHM of 19.8?nm at output power of 210 mW has been realized.", "author_names": [ "Yan-biao Wang", "Sha Wang", "Guoying Feng", "Shou-huan Zhou" ], "corpus_id": 126236891, "doc_id": "126236891", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "SESAM combined Kerr lens mode locked Yb:CALGO laser pumped by a 1.2 W single mode fiber coupled laser diode", "venue": "", "year": 2017 }, { "abstract": "A new design hybrid passive harmonic mode locked fiber laser with integrated Faraday rotator and SESAM in sigma configuration is built. The integrated SESAM Faraday rotator acts as the mode locker. A MZ modulator provides amplitude modulation to stabilize and order optical pulses. Stable evenly spaced femtosecond optical pulses are generated.", "author_names": [ "Kevin L F Lui", "K S Tsang", "Mary Lena Fung", "Victor W L Ho", "Hideaki Furukawa", "Takeshi Makino", "Tetsuya Kobayashi", "Xiaomin Wang", "Naoya Wada", "Ray Man" ], "corpus_id": 24175639, "doc_id": "24175639", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Passive hybrid harmonic mode locked fiber sigma laser using integrated faraday rotator and SESAM with amplitude modulation stabilization", "venue": "2017 Conference on Lasers and Electro Optics Pacific Rim (CLEO PR)", "year": 2017 }, { "abstract": "A major design goal for femtosecond fiber lasers is to increase the output power but not at the cost of increasing the noise level or narrowing the bandwidth. Here, we perform a computational study to optimize the cavity design of a femtosecond fiber laser that is passively modelocked with a semiconductor saturable absorbing mirror (SESAM) We use dynamical methods that are more than a thousand times faster than standard evolutionary methods. We show that we can obtain higher pulse energies and hence higher output powers by simultaneously increasing the output coupling ratio, the gain, and the anomalous group delay dispersion. We can obtain output pulses that are from 5 to 15 times the energy of the pulse in the current experimental design with no penalty in the noise level or bandwidth.", "author_names": [ "Shaokang Wang", "Chaoran Tu", "Seyed Ehsan Jamali Mahabadi", "Stefan Droste", "Laura C Sinclair", "Ian Coddington", "Nathan R Newbury", "Thomas F Carruthers", "Curtis R Menyuk" ], "corpus_id": 220629643, "doc_id": "220629643", "n_citations": 2, "n_key_citations": 0, "score": 1, "title": "Obtaining more energetic modelocked pulses from a SESAM based fiber laser.", "venue": "Optics express", "year": 2020 } ]

[ { "abstract": "Abstract The ability to exploit data driven process control and decision making frameworks is rapidly becoming critical to success in semiconductor manufacturing. At the same time, advances in manufacturing equipment sensors has seen dramatic increases in sampling rates in recent years, which has led to the ability to capture transients effects in signals with higher fidelity than previously possible. It is known that data driven process control and decision making methodologies rely on the process of extraction of useful information from raw data signals. To that end, the current manuscript presents a novel methodology for extraction of information from data in the form of a feature set that faithfully and reliably depicts both the transient and stationary portions of the signals. The solution proposed is an automated dynamics inspired approach that looks to segment a signal into steady state and transient components before summarizing each segment into a set of relevant signatures. The steady state segments are summarized through a set of statistics and each transient is reduced to a set of parameters relating to the underlying system dynamics, such as settling time, rise time, overshoots, etc. The impactful novel information content of the resulting dynamics inspired feature set is evaluated by application to chamber matching, product defect level prediction and product quality characteristic prediction in etch and deposition processes executed in various tools across several modern 300 mm fabs.", "author_names": [ "Asad Arsalan Ul Haq", "Dragan Djurdjanovic" ], "corpus_id": 139241888, "doc_id": "139241888", "n_citations": 4, "n_key_citations": 0, "score": 1, "title": "Dynamics inspired feature extraction in semiconductor manufacturing processes", "venue": "Journal of Industrial Information Integration", "year": 2019 }, { "abstract": "Wafer maps contain information about various defect patterns on the wafer surface and automatic classification of these defects plays a vital role to find their root causes. Semiconductor engineers apply various methods for wafer defect classification such as manual visual inspection or machine learning based algorithms by manually extracting useful features. However, these methods are unreliable, and their classification performance is also poor. Therefore, this paper proposes a deep learning based convolutional neural network for automatic wafer defect identification (CNN WDI) We applied a data augmentation technique to overcome the class imbalance issue. The proposed model uses convolution layers to extract valuable features instead of manual feature extraction. Moreover, state of the art regularization methods such as batch normalization and spatial dropout are used to improve the classification performance of the CNN WDI model. The experimental results comparison using a real wafer dataset shows that our model outperformed all previously proposed machine learning based wafer defect classification models. The average classification accuracy of the CNN WDI model with nine different wafer map defects is 96.2% which is an increment of 6.4% from the last highest average accuracy using the same dataset.", "author_names": [ "Muhammad Saqlain", "Qasim Abbas", "Jong Yun Lee" ], "corpus_id": 219459186, "doc_id": "219459186", "n_citations": 10, "n_key_citations": 1, "score": 0, "title": "A Deep Convolutional Neural Network for Wafer Defect Identification on an Imbalanced Dataset in Semiconductor Manufacturing Processes", "venue": "IEEE Transactions on Semiconductor Manufacturing", "year": 2020 }, { "abstract": "Abstract: Management and analytics for inline manufacturing process data has become a critical but increasingly complex task in the semiconductor fabrication industry. The importance of new methods for construction of informative features has been accentuated by advancements in the data collection technology employed in this industry, which has recently increased sampling rates for inline data from values below 1 Hz to frequencies in excess of 10Hz. In this paper, a new feature construction method is proposed that aims to extract as much of the information accessible with these increased sampling rates as possible, while simultaneously minimizing redundancy and user involvement. The proposed method results in a meaningful dynamics inspired feature set, which provides insight into the underlying process and equipment dynamics. The advantages offered by this feature set are established using data collected at several modern 300mm fabs, for chamber and tool matching tasks, as well as wafer defect level prediction.", "author_names": [ "Asad Ul Haq", "Keren Wang", "Dragan Djurdjanovic" ], "corpus_id": 114538961, "doc_id": "114538961", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Feature Construction for Dense Inline Data in Semiconductor Manufacturing Processes", "venue": "", "year": 2016 }, { "abstract": "In semiconductor manufacturing processes, it is important to quickly identify any signs of the occurrence of defects. We applied a time series clustering method to the signal data of processing equipment and obtained information related to the occurrence of defects. By using the information as the feature values of a prediction model, we were able to predict defects more accurately than by using only conventional feature values.", "author_names": [ "Daisuke Hamaguchi", "Tomonari Masada", "Takumi Eguchi" ], "corpus_id": 232373732, "doc_id": "232373732", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Feature Extraction from Equipment Sensor Signals with Time Series Clustering and Its Application to Defect Prediction", "venue": "2020 International Symposium on Semiconductor Manufacturing (ISSM)", "year": 2020 }, { "abstract": "Reliable feature extraction, condition monitoring, and fault modeling are critical to understanding equipment degradation and implementing the proper maintenance decisions in manufacturing processes. Semiconductor manufacturing machines are highly sophisticated systems, consisting of multiple interacting components operating in highly variable operating conditions. This complicates performance monitoring since equipment condition must often be inferred through concurrent interpretation of multiple sensor readings originating from potentially very different subsystems of the tool. This paper presents an integrated approach to feature extraction, condition monitoring, and fault modeling applied to a set of standard built in sensors on a modern 300 mm technology industrial Plasma Enhanced Chemical Vapor Deposition (PECVD) tool. Linear Discriminant Analysis was utilized to determine the set of dynamic features that are the most sensitive to different tool conditions brought about by chamber cleaning or various faults. Gaussian Mixture Models of the dynamic feature distributions were used to statistically quantify changes of these features as the condition of the tool changed. In addition, four highly detrimental faults were analyzed to demonstrate the fault modeling methodology. Data collected over 8 months from a PECVD tool being operated by a major microelectronics manufacturer was used to verify the methodology. Top sensitive features from various faults observed in this period were examined and physical connections to the chamber condition were interpreted through their behavior.", "author_names": [ "Alexander Bleakie", "Dragan Djurdjanovic" ], "corpus_id": 35291919, "doc_id": "35291919", "n_citations": 30, "n_key_citations": 1, "score": 0, "title": "Feature extraction, condition monitoring, and fault modeling in semiconductor manufacturing systems", "venue": "Comput. Ind.", "year": 2013 }, { "abstract": "A variety of statistical and data mining techniques have been developed for the fault detection (FD) modeling of semiconductor manufacturing processes over the past three decades. However, few studies have analyzed which models are adequate for different types of fault data. In this paper, we define a FD model as an algorithm combining feature extraction, feature selection, and classification. We prepare six process data scenarios and collect data by simulating an etching tool. In total, 117 possible algorithm combinations are tested as FD models for the six datasets. With these test results, we conduct statistical analyses from two perspectives: 1) the algorithm perspective and 2) FD model perspective. From the algorithm perspective, we compare the performance of competing algorithms in the three model building steps using multiple comparison methods and discuss the advantages and disadvantages of individual algorithms. From the model perspective, we determine which algorithm combinations are recommended for FD models of the semiconductor process and explain why some combinations do not exhibit the expected performance. In both analyses, we interpret some results using 3 D plots.", "author_names": [ "Taehyung Lee", "Chang Ouk Kim" ], "corpus_id": 22894797, "doc_id": "22894797", "n_citations": 17, "n_key_citations": 2, "score": 0, "title": "Statistical Comparison of Fault Detection Models for Semiconductor Manufacturing Processes", "venue": "IEEE Transactions on Semiconductor Manufacturing", "year": 2015 }, { "abstract": "As semiconductor manufacturing processes become more complex and sophisticated, manufacturers demand high quality, efficient process monitoring and fault detection (FD) Segmentation feature extraction (SFE) has been shown to be successful in FD when the anomaly patterns are well described by feature extraction, but not in cases of complex anomaly patterns. This paper proposes a novel approach that combines feature extraction based and full trace analysis (FTA) capabilities in FD. First, a novel multivariate trace segmentation is applied to segment trace data based on defined patterns across key sensors, and then the pattern features and parameters are extracted within each segment. Second, full trace analysis generates adaptive guardbands on key sensors. These guardbands detect \"anomaly\" throughout the whole trace with a certain confidence interval. Third, a multivariate fault detection model is developed that combines SFE and FTA capabilities. Furthermore, multivariate data generation is developed to exhaustively validate combination and isolation of the proposed capabilities. Experimental results indicate that FTA can better capture the anomaly features with complex/atypical patterns, and the combined capability of SFE FTA exhibits better performance than each method applied individually.", "author_names": [ "Fei Li", "Haoshu Cai", "James R Moyne", "Jimmy Iskandar", "Michael Armacost", "Jay Lee" ], "corpus_id": 235206427, "doc_id": "235206427", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Combining Feature Extraction Based and Full Trace Analysis Capabilities in Fault Detection: Methods and Comparative Analysis", "venue": "2021 32nd Annual SEMI Advanced Semiconductor Manufacturing Conference (ASMC)", "year": 2021 }, { "abstract": "Feature design and selection is challenging because of huge data volume and high mix production systems. Most engineers still rely on human experts to suggest the specific sensor channel and specific time frames of data from which to design the features. This study proposes a novel approach for important sensor screening to prioritize the useful sensor channels for FDC model development in semiconductor manufacturing. The proposed method can be used as a pre processing step prior to feature extraction, and the selected sensor channels can be leveraged by process engineers for finer feature design. In this research, firstly, time series alignment kernels (TSAKs) are proposed to handle multivariate trace data. Then, the proposed method combines 5 different time series alignment kernels (TSAKs) with a feature selection algorithm, minimum Redundancy Maximum Relevance (mRMR) to identify the important sensor channels. Furthermore, a TSAK+Kernel Principal Component Analysis (KPCA) algorithm is proposed for a visualization tool. Lastly, the TSAK+Support Vector Machine (SVM) is employed for results validation. In this study, validation of the proposed method is based on both open source datasets and the proprietary datasets from a real production line.", "author_names": [ "Feng Zhu", "Xiaodong Jia", "Marcella Miller", "Xinong Li", "Fei Li", "Yinglu Wang", "Jay Lee" ], "corpus_id": 229263252, "doc_id": "229263252", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Methodology for Important Sensor Screening for Fault Detection and Classification in Semiconductor Manufacturing", "venue": "IEEE Transactions on Semiconductor Manufacturing", "year": 2021 }, { "abstract": "Big data related to manufacturing applications has the traits such as great quantity, multi sources, low value density, high complexity, and dynamic state. Traditional feature extraction methods are incapable of meeting real time demands. Therefore, a robust incremental on line feature extraction method based on PCA (Principal Component Analysis) RIPCA (Robust Incremental Principal Component Analysis) is proposed. RIPCA adopts a sliding window to update new coming data stream and to filter outliers. The proposed method could ensure the accuracy of data analysis and meet real time demands of big data processing for manufacturing applications. A test data set based on a semiconductor manufacturing process containing 1567 records with 590 features is used to demonstrate the availability of the proposed method. Experimental results show that the method can effectively extract features of the data stream in real time with high accuracy.", "author_names": [ "Xianguang Kong", "Jiantao Chang", "Meng Niu", "Xiaoyu Huang", "Jihu Wang", "Shing I Chang" ], "corpus_id": 113828191, "doc_id": "113828191", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Research on real time feature extraction method for complex manufacturing big data", "venue": "", "year": 2018 }, { "abstract": "Nowadays, more attention has been placed on cost reductions and yield enhancement in the semiconductor industry. During the manufacturing process, a considerable amount of sensor data called status variables identification (SVID) is collected by sensors embedded in advanced machines. This data is a valuable source for data driven automatic fault detection and diagnosis at an early manufacturing stage to maintain competitive advantages. However, wafer processing times vary slightly from wafer to wafer, resulting in variable length signal data. The conventional approaches use much condensed data called fault detection and classification (FDC) data made by manually designed feature extraction. Or, recent deep learning approaches assume that all wafers have the same processing time, which is impotent to the variable length SVID. To detect and diagnose faults directly from the variable length SVID, we propose a self attentive convolutional neural network. In experiments using real world data from a semiconductor manufacturer, the proposed model outperformed other deep learning models with less training time and showed robustness at different sequence lengths. Compared to FDC data, SVID data showed better fault detection performance. Without manually investigating the lengthy sensor signals, abnormal sensor value patterns were found at the time specified by the model.", "author_names": [ "Eunji Kim", "Sungzoon Cho", "Byeongeon Lee", "Myoungsu Cho" ], "corpus_id": 181710095, "doc_id": "181710095", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Fault Detection and Diagnosis Using Self Attentive Convolutional Neural Networks for Variable Length Sensor Data in Semiconductor Manufacturing", "venue": "IEEE Transactions on Semiconductor Manufacturing", "year": 2019 } ]

[ { "abstract": "This paper presents the results of our measurement of the room temperature thermal conductivity of the Ga1 xAlxAs alloy system. The study was motivated by our need to characterize the thermal properties of cw heterostructure lasers, in which the heat generated in the optically active layer must flow through a substantial thickness of Ga1 xAlxAs to reach the heat sink. The measurement was made on LPE layers which were separated from their substrates and fashioned into rectangular bars. A steady state heat flow was established in the bars utilizing an argon laser as the heat source, and the conductivity was obtained by measuring the temperature gradient in the bars with thin films of cholesteric liquid crystals. The results indicate that the thermal conductivity of the alloy is well described by an existing theoretical treatment of high temperature lattice thermal conductivity of disordered semiconductor alloys. In the Ga1 xAlxAs system, the increased thermal resistivity of the alloy is shown to be a result.", "author_names": [ "Martin A Afromowitz" ], "corpus_id": 122292701, "doc_id": "122292701", "n_citations": 145, "n_key_citations": 2, "score": 1, "title": "Thermal conductivity of Ga1 xAlxAs alloys", "venue": "", "year": 1973 }, { "abstract": "Some materials such as Cu2 xSe, Cu1.97Ag0.03Se, and SnSe have attracted attention by demonstrating a significant enhancement of their thermoelectric performance, which is associated with a phase transition. This phenomenon, observed in a limited temperature (T) interval, results in sharp changes of the Seebeck coefficient (S) the electrical resistivity (r) and the thermal conductivity (k) which may render the correct evaluation of the dimensionless figure of merit (ZT) difficult. We report the thermoelectric properties of a polycrystalline Cu2 xSe sample which is known to undergo a phase transition near 410 K, containing a mixture of a and b phases at room temperature, as determined by x ray diffraction measurements. We have used a Harman based setup (TEMTE Inc. which assures the direct measurement of ZT at all temperatures, including the phase transition region. This approach ensures that k(T) is determined under steady state conditions at any given temperature, including points arbitrarily close to the transition temperature which cannot be guaranteed by previously used techniques such as laser flash. We have observed a sharp maximum for k(T) near 410 K, similar to the reported specific heat variation, with a ZT peak value of 0.2 at 400 K. The expected gain in ZT related to the phase transition is reduced because the increase in S is counterbalanced by the increase in k(T) Thus, our detailed assessment of the temperature variation of the individual thermoelectric properties accurately evaluates the performance enhancement associated to a structural phase transition and helps to elucidate this complex phenomenon.", "author_names": [ "Dmitriy I Vasilevskiy", "Mohsen K Keshavarz", "J -M Simard", "Remo A Masut", "Sylvain Turenne", "Gerald Jeffrey Snyder" ], "corpus_id": 103941508, "doc_id": "103941508", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Assessing the Thermal Conductivity of Cu2 xSe Alloys Undergoing a Phase Transition via the Simultaneous Measurement of Thermoelectric Parameters by a Harman Based Setup", "venue": "Journal of Electronic Materials", "year": 2018 }, { "abstract": "In this research, effects of Zn and Cu content on microstructure, mechanical properties, electric and thermal conductivity of the as extruded Al x(Zn+0.5Cu) alloys were investigated. As the content of Zn and Cu increased, the area ratio of Al2Cu intermetallic compounds increased. After homogenization treatment and extrusion process, most of Al2Cu intermetallic compounds was disappeared due to solution in Al matrix of Cu atoms. As the (Zn+0.5Cu) content increased from 1 to 2 wt. the average grain size decreased remarkably from 645 to 227 mm due to the dynamic recrystallization caused by the solute Zn and Cu atoms during the extrusion. With increasing Zn and Cu additions, the thermal conductivity was decreased from 225 (x 1) to 208 (x 2) and 183 W/mK (x 4) due to electric scattering by solute Zn and Cu atoms. The ultimate tensile strength (UTS) of the as extruded Al x(1Zn+0.5Cu) alloys improved remarkably from 77 (x 1) to 142 MPa (x 4) as Zn and Cu content increased, and the elongation increased from 30 to 33% This improvement in the strength resulted from the grain refinement and solid solution strengthening due to the solute Zn and Cu atoms. The Zn and Cu addition in Al alloy played an important role in thermal conductivity and mechanical properties.", "author_names": [ "Yong-Ho Kim", "H Yoo", "Hyeon Taek Son" ], "corpus_id": 210867746, "doc_id": "210867746", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Microstructure, Mechanical Properties, Electric and Thermal Conductivity of the As Extruded Al x(1.0 wt. Zn 0.5 wt. Cu) Alloys (x 1, 2 and 4)", "venue": "Journal of nanoscience and nanotechnology", "year": 2020 }, { "abstract": "In this study, we investigated the effect of Mg addition (0, 0.5, and 1.0 wt% on the microstructure, mechanical properties, and thermal conductivity of as extruded Al RE alloys. With an increase in the Mg content from 0 to 1.0 wt% the average grain size of the alloys decreased remarkably from 740 to 130 mm and the high angle grain boundary fraction increased from 35 to 54% The addition of Mg resulted in the grain refinement of the Al 1.0RE alloy because of the dynamic recrystallization caused by the solute Mg atoms during the extrusion. With an increase in the Mg content from 0.5 to 1.0 wt% thermal conductivity of the alloy decreased from 231 to 193 W/mK because of the electric scattering caused by the solute Mg atoms. With an increase in the Mg content from 0 to 1.0 wt% the ultimate tensile strength of the alloy increased remarkably from 74 to 120 MPa, while the strain reduced from 44 to 34% This improvement in the strength resulted from the grain refinement and solid solution strengthening due to the solute Mg atoms. The Mg addition amount affected the thermal conductivity and strength of the alloys significantly.", "author_names": [ "Yong-Ho Kim", "H Yoo", "Seong Ho Lee", "Gyu-Seok Lee", "Hyeon Taek Son" ], "corpus_id": 199449810, "doc_id": "199449810", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Effects of Mg Addition on Microstructure, Mechanical Properties, and Thermal Conductivity of As Extruded Al RE Alloys.", "venue": "Journal of nanoscience and nanotechnology", "year": 2020 }, { "abstract": "The microstructure and thermal conductivity of four groups of Mg rare earth (RE) binary alloys (Mg Ce, Mg Nd, Mg Y and Mg Gd) in as cast and as solutionized states were systematically studied. Thermal conductivity was measured on a Netzsch LFA457 using laser flash method at room temperature. Results indicated that for as cast alloys, the volume fraction of second phases increased with the increase of alloying elements. After solutionizing treatment, a part or most of second phases were dissolved in a Mg matrix, except for Mg Ce alloys. The thermal conductivity of as cast and as solutionized Mg RE alloys decreased with the increase of concentrations. The thermal conductivity of as solutionized Mg Nd, Mg Y and Mg Gd alloys was lower than that of as cast alloys. Thermal conductivity of as solutionized Mg Ce alloys was higher than that of as cast alloys, because of the elimination of lattice defects and fine dispersed particles during solutionizing treatment. Different RE elements have different influences on the thermal conductivity of Mg alloys in the following order: Ce", "author_names": [ "Liping Zhong", "Jian Peng", "Son Il Sun", "Yongjiang Wang", "Yun Lu", "Fu-sheng Pan" ], "corpus_id": 138744052, "doc_id": "138744052", "n_citations": 34, "n_key_citations": 1, "score": 0, "title": "Microstructure and Thermal Conductivity of As Cast and As Solutionized Mg Rare Earth Binary Alloys", "venue": "", "year": 2017 }, { "abstract": "This study investigated the microstructure and thermal conductivity of as cast and as extruded binary Mg Mn alloys. The large grains and fine a Mn particles contained in the as cast alloys were observed. After extrusion, the average grain sizes significantly decreased, typical basal fibre texture was generated and high amount of nano particles precipitated from the a Mg matrix. The thermal conductivity of both as cast and as extruded Mg Mn alloys gradually decreased with the increase in Mn concentration. As extruded alloys exhibited lower thermal conductivity than as cast alloys except for the as extruded alloys containing higher Mn concentrations >1.2 wt Mn) Compared with binary as extruded Mg Al and Mg Zn alloys reported in literatures, thermal conductivity of the as extruded Mg Mn alloys was higher when the solute content was greater than 0.5 at.", "author_names": [ "Liping Zhong", "Jian Peng", "Y Sun", "Yongjiang Wang", "Yun Lu", "Fu-sheng Pan" ], "corpus_id": 138179176, "doc_id": "138179176", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Microstructure and thermal conductivity of as cast and as extruded binary Mg Mn alloys", "venue": "", "year": 2017 }, { "abstract": "Abstract In the present work, the thermal conductivities and microstructure of Al x wt% Cu x 1, 3, 5, 15 and 30) and Al y wt% Si y 2, 12.5 and 20) alloys were investigated by using laser flash method, scanning electron microscopy (SEM) and X ray diffraction (XRD) Besides, a CALPHAD (CALculation of PHAse Diagram) approach to evaluate the thermal conductivity of Al Cu Mg Si system was performed. The numerical models for the thermal conductivity of pure elements and stoichiometric phases were described as polynomials, and the coefficients were optimized via PARROT module of Thermal Calc software applied to the experimental data. The thermal conductivity of (Al) based solid solutions was described by using Redlich Kister interaction parameters. For alloys in two phase region, the interface scattering parameter was proposed in the modeling to describe the impediment of interfaces on the heat transfer. Finally, a set of self consistent parameters for the description of thermal conductivity in Al Cu Mg Si system was obtained, and comprehensive comparisons between the calculated and measured thermal conductivities show that the experimental information is satisfactorily accounted for by the present modeling.", "author_names": [ "Cong Zhang", "Yong Du", "Shuhong Liu", "Yuling Liu", "Bo Sundman" ], "corpus_id": 138939431, "doc_id": "138939431", "n_citations": 24, "n_key_citations": 1, "score": 0, "title": "Thermal conductivity of Al Cu Mg Si alloys: Experimental measurement and CALPHAD modeling", "venue": "", "year": 2016 }, { "abstract": "In the present work, the effects of Sn, Ca additions on thermal conductivity were investigated in as cast Mg Sn Ca alloys. The measured values of thermal conductivity of Mg 3Sn xCa alloys obviously increased from 85.6 to 126.3 W m 1 K 1 with the increasing Ca from 0 to 1.5 wt and then decreased to 98.3 W m 1 K 1 with the 2.5 wt Ca. In addition, the thermal conductivity of the Mg Sn Ca (Sn/Ca atomic ratio of 1) alloys decreased slightly from 154.2 to 132.1 W m 1 K 1 with the increasing Sn, Ca. Meanwhile, the microstructures of the selected alloys were discussed in detail, suggesting that the solute atoms that caused lattice distortion had greater effect on thermal conductivity compared with the second phases formed in as cast Mg Sn Ca alloys.", "author_names": [ "Chunming Wang", "Zhen-bao Liu", "Sufen Xiao", "Yungui Chen" ], "corpus_id": 135809492, "doc_id": "135809492", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Effects of Sn, Ca additions on thermal conductivity of Mg matrix alloys", "venue": "", "year": 2016 }, { "abstract": "This article examines factors affecting the thermal conductivity of aluminium alloys. More specifically, thermal conductivity is measured with the Hot Disk method. The work shows that improvements as high as 50 in thermal conductivity can be achieved through heat treatment of the studied alloys. Optical microscopy and scanning electron microscopy indicate that some elements in solid solution (particularly silicon) precipitate in aluminium grains during annealing. Modifying the microstructure with strontium and sodium increases thermal conductivity slightly, whereas rheocasting and grain refinement treatments do not affect thermal conductivity. AlB treatment improves thermal conductivity especially in low silicon primary aluminium alloys. As cast and heat treated thermal conductivities of the studied alloys are calculated by applying Matthiessen's rule and the Wiedemann Franz law and compared to the measured thermal conductivity.", "author_names": [ "Veijo Rauta", "Celal Cingi", "Juhani Orkas" ], "corpus_id": 137931325, "doc_id": "137931325", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Effect of Annealing and Metallurgical Treatments on Thermal Conductivity of Aluminium Alloys", "venue": "International Journal of Metalcasting", "year": 2016 }, { "abstract": "Abstract The Wiedemann Franz Law is often used to calculate the thermal conductivity of Fe from experimental measurements of the electrical conductivity. It is shown by measurements of the Seebeck coefficient (S) of solid and liquid Fe at pressures up to 6 GPa and temperatures up to 2100 K that the Sommerfeld value L 0 2.445 x 10 8 W O K 2 of the Lorenz number L represents more than 99% of the electronic component of the thermal conductivity of Fe. Using experimental values of electrical resistivity and thermal conductivity of Fe, L L 0 is shown to vary by as much as 1.22 in the solid state and 1.32 in the liquid state, signifying a non negligible phonon component. An expression for the pressure dependence of L at the melting boundary up to 5 GPa is derived for electron phonon scattering. For Fe Si alloys, L L 0 varies more than for pure Fe and generally increases with increasing Si and state of disorder. New values for the conductive heat flow in a pure Fe core of Mercury are presented.", "author_names": [ "Richard A Secco" ], "corpus_id": 132653953, "doc_id": "132653953", "n_citations": 43, "n_key_citations": 5, "score": 0, "title": "Thermal conductivity and Seebeck coefficient of Fe and Fe Si alloys: Implications for variable Lorenz number", "venue": "", "year": 2017 } ]

[ { "abstract": "1. SEMICONDUCTORS, JUNCTIONS AND MOFSET OVERVIEW 2. THE TWO TERMINAL MOS STRUCTURE 3. THE THREE TERMINAL MOS STRUCTURE 4. THE FOUR TERMINAL MOS STRUCTURE 5. MOS TRANSISTORS WITH ION IMPLANTED CHANNELS 6. SMALL DIMENSION EFFECTS 7. THE MOS TRANSISTOR IN DYNAMIC OPERATION LARGE SIGNAL MODELING 8. SMALL SIGNAL MODELING FOR LOW AND MEDIUM FREQUENCIES 9. HIGH FREQUENCY SMALL SIGNAL MODELS 10.MOFSET MODELING FOR CIRCUIT SIMULATION", "author_names": [ "Yannis P Tsividis" ], "corpus_id": 137446586, "doc_id": "137446586", "n_citations": 3154, "n_key_citations": 317, "score": 1, "title": "Operation and modeling of the MOS transistor", "venue": "", "year": 1987 }, { "abstract": "", "author_names": [ "Yannis P Tsividis" ], "corpus_id": 108137416, "doc_id": "108137416", "n_citations": 91, "n_key_citations": 1, "score": 0, "title": "Operation and Modeling of the Mos Transistor (The Oxford Series in Electrical and Computer Engineering)", "venue": "", "year": 2004 }, { "abstract": "A unified modeling approach for the submicron MOS transistor charge/capacitance characteristics in all operation regions is presented. The development of the MOS charge model is based on the charge density approximation to reduce the complexity of the expression. The unified charge densities in gate, channel, and bulk are obtained with assistance of the sigmoid, hyperbola, and exponential interpolation techniques. By carrying out the integration of the charge densities along the channel area, the terminal charges associated with gate and bulk can be obtained. The non reciprocal capacitance behavior is well realized in this model. Good agreement between the measurement data and simulation results is obtained.", "author_names": [ "Steve H Jen", "Bing J Sheu", "A Yoondong Park" ], "corpus_id": 62210692, "doc_id": "62210692", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "An efficient MOS transistor charge/capacitance model with continuous expressions for VLSI", "venue": "ISCAS '98. Proceedings of the 1998 IEEE International Symposium on Circuits and Systems (Cat. No.98CH36187)", "year": 1998 }, { "abstract": "An accurate and computationally efficient charge based model for the intrinsic capacitances in MOS transistors is proposed. The model is valid in the subthreshold regime and is based on the quasi static approximation. By integrating this model with a corresponding one in the strong inversion regime, a complete model valid in all regions of operation is presented. An interpolation scheme which guarantees the continuity of the drain current and the capacitances as well as their derivatives is used to provide a smooth transition from subthreshold to strong inversion. The theoretical predictions of the model are compared to the numerically simulated data extracted from MINIMOS 4.0 and are found to be in good agreement over a wide range of voltages.<ETX>", "author_names": [ "A Kushaa", "M A El Nokali" ], "corpus_id": 108561196, "doc_id": "108561196", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "A CAD model for MOS transistors valid in all regions of operation", "venue": "[1991] Proceedings of the 34th Midwest Symposium on Circuits and Systems", "year": 1991 }, { "abstract": "We present a circuit architecture for compact analog VLSI implementation of the Izhikevich neuron model, which efficiently describes a wide variety of neuron spiking and bursting dynamics using two state variables and four adjustable parameters. Log domain circuit design utilizing MOS transistors in subthreshold results in high energy efficiency, with less than 1pJ of energy consumed per spike. We also discuss the effects of parameter variations on the dynamics of the equations, and present simulation results that replicate several types of neural dynamics. The low power operation and compact analog VLSI realization make the architecture suitable for human machine interface applications in neural prostheses and implantable bioelectronics, as well as large scale neural emulation tools for computational neuroscience.", "author_names": [ "Venkat Rangan", "Abhishek Ghosh", "Vladimir Aparin", "Gert Cauwenberghs" ], "corpus_id": 16054180, "doc_id": "16054180", "n_citations": 44, "n_key_citations": 1, "score": 0, "title": "A subthreshold aVLSI implementation of the Izhikevich simple neuron model", "venue": "2010 Annual International Conference of the IEEE Engineering in Medicine and Biology", "year": 2010 }, { "abstract": "BACKGROUND Death within 90 days after total hip replacement is rare but might be avoidable dependent on patient and treatment factors. We assessed whether a secular decrease in death caused by hip replacement has occurred in England and Wales and whether modifiable perioperative factors exist that could reduce deaths. METHODS We took data about hip replacements done in England and Wales between April, 2003, and December, 2011, from the National Joint Registry for England and Wales. Patient identifiers were used to link these data to the national mortality database and the Hospital Episode Statistics database to obtain details of death, sociodemographics, and comorbidity. We assessed mortality within 90 days of operation by Kaplan Meier analysis and assessed the role of patient and treatment factors by Cox proportional hazards model. FINDINGS 409,096 primary hip replacements were done to treat osteoarthritis. 1743 patients died within 90 days of surgery during 8 years, with a substantial secular decrease in mortality, from 0*56% in 2003 to 0*29% in 2011, even after adjustment for age, sex, and comorbidity. Several modifiable clinical factors were associated with decreased mortality according to an adjusted model: posterior surgical approach (hazard ratio [HR] 0*82, 95% CI 0*73 0*92; p=0*001) mechanical thromboprophylaxis (0*85, 0*74 0*99; p=0*036) chemical thromboprophylaxis with heparin with or without aspirin (0*79, 0*66 0*93; p=0*005) and spinal versus general anaesthetic (0*85, 0*74 0*97; p=0*019) Type of prosthesis was unrelated to mortality. Being overweight was associated with lower mortality (0*76, 0*62 0*92; p=0*006) INTERPRETATION Postoperative mortality after hip joint replacement has fallen substantially. Widespread adoption of four simple clinical management strategies (posterior surgical approach, mechanical and chemical prophylaxis, and spinal anaesthesia) could, if causally related, reduce mortality further. FUNDING National Joint Registry for England and Wales.", "author_names": [ "Linda P Hunt", "Yoav Ben-Shlomo", "Emma M Clark", "P A Dieppe", "Andrew Judge", "Alexander J Macgregor", "Jonathan H Tobias", "Kelly Vernon", "Ashley W Blom" ], "corpus_id": 2279212, "doc_id": "2279212", "n_citations": 244, "n_key_citations": 11, "score": 0, "title": "90 day mortality after 409 096 total hip replacements for osteoarthritis, from the National Joint Registry for England and Wales: a retrospective analysis", "venue": "The Lancet", "year": 2013 }, { "abstract": "Qucs and QucsStudio open source circuit simulators have a wealth of built in swept data features, including facilities for linear and logarithmic scans of simulation variables and for setting component values and device parameters. These simulators also allow semicolon separated lists of numerical values to be used as swept data. This little known feature provides a very flexible mechanism for generating component and device parameter statistical data. An outline of a statistical circuit simulation technique is presented in this paper. The proposed technique can be used with any general purpose circuit simulator equipped with swept data capabilities and as such is suitable for the study of device and circuit performance resulting from variations in device parameters and component values. The operation of the proposed simulation technique is illustrated with the results from an investigation of the statistical performance of a simple MOS current mirror integrated circuit cell, modeled with a speed optimized Verilog A version of a long channel EPFL EKV v2.6 MOS transistor model.", "author_names": [ "Mike Brinson" ], "corpus_id": 18009567, "doc_id": "18009567", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A swept parameter technique for statistical circuit simulation", "venue": "Proceedings of the 20th International Conference Mixed Design of Integrated Circuits and Systems MIXDES 2013", "year": 2013 }, { "abstract": "Design, operation and measurement results of a CMOS camera implemented within a SOI wafer are presented. The peak of photodiode quantum efficiency is obtained for the wavelengths of 400 500 nm. In addition, noise measurements of the 1/f noise in P MOS and N MOS transistors for analog applications are reported under wide bias conditions ranging from subthreshold to saturation. Two implementations (in regular and SOI wafers) of 0.35 /spl mu/m CMOS analog process are compared and it is found that they exhibit similar 1/f noise. The results of this study are useful to the design and modeling of 1/f noise of CMOS analog circuits.", "author_names": [ "Igor Brouk", "Yael Nemirovsky" ], "corpus_id": 5492957, "doc_id": "5492957", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "CMOS SOI image sensor", "venue": "Proceedings of the 2004 11th IEEE International Conference on Electronics, Circuits and Systems, 2004. ICECS 2004.", "year": 2004 }, { "abstract": "For class E power amplifier circuits operating at switching frequencies of the MHz range or higher, the parasitic capacitance of the MOS transistor switch becomes a significant part of the circuit adding to the usual intended circuit components. For the class E power amplifier, this is often regarded as an advantage because the parasitic capacitor can be utilized for achieving zero voltage and current switchings, thus reducing the size of an external capacitor which has to be inserted. However, parallel connection of parasitic, stray and external capacitors may give rise to high frequency ringings of the voltage across the switch, causing the circuit to deviate from the desired class E operation. In this paper, the phenomenon and its underlying cause is studied by simulations and experiments. A circuit model of the amplifier with parasitic or stray components is developed to explain the phenomenon.", "author_names": [ "Hao Zhang", "Siu-Chung Wong", "C K Michael Tse", "Xikui Ma" ], "corpus_id": 4655351, "doc_id": "4655351", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Study of parasitic and stray components induced ringings in class E power amplifiers in MHz range", "venue": "Proceedings of the 2005 European Conference on Circuit Theory and Design, 2005.", "year": 2005 }, { "abstract": "This paper presents a graphical approach for the application of a compact current based MOS model, valid in all regimes of operation, in the design of CMOS operational transconductance amplifiers. Since a large amount of information is made available in the form of contour plots, the method provides a deep insight of design feasibility and allows a rapid and reliable determination of transistor dimensions that satisfy design specifications and saturation conditions. The adjustable contour plots are generated by a sizing program implemented in MATLAB.", "author_names": [ "H C M Santos", "Ana Isabela Araujo Cunha" ], "corpus_id": 11760478, "doc_id": "11760478", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "Application of ACM model to the design of CMOS OTA through a graphical approach", "venue": "Proceedings of the 2003 International Symposium on Circuits and Systems, 2003. ISCAS '03.", "year": 2003 } ]

[ { "abstract": "Tailoring tandem organics Tandem solar cells can boost efficiency by using a wider range of the solar spectrum. The bandgap of organic semiconductors can be tuned over a wide range, but, for a two terminal device that directly connects the cells, the currents produced must be nearly equal. Meng et al. used a semiempirical analysis to choose well matched top and bottom cell active layers. They used solution processing to fabricate an inverted tandem device that has a power conversion efficiency as high as 17.4% Science, this issue p. 1094 A semi empirical analysis helped to optimize materials for a tandem organic solar cell with high power conversion efficiency. Although organic photovoltaic (OPV) cells have many advantages, their performance still lags far behind that of other photovoltaic platforms. A fundamental reason for their low performance is the low charge mobility of organic materials, leading to a limit on the active layer thickness and efficient light absorption. In this work, guided by a semi empirical model analysis and using the tandem cell strategy to overcome such issues, and taking advantage of the high diversity and easily tunable band structure of organic materials, a record and certified 17.29% power conversion efficiency for a two terminal monolithic solution processed tandem OPV is achieved.", "author_names": [ "Lingxian Meng", "Yamin Zhang", "Xiangjian Wan", "Chenxi Li", "Xin Zhang", "Yanbo Wang", "Xin Ke", "Zuo Xiao", "Liming Ding", "Ruoxi Xia", "Hin-Lap Yip", "Yong Cao", "Yongsheng Chen" ], "corpus_id": 206667051, "doc_id": "206667051", "n_citations": 1638, "n_key_citations": 5, "score": 1, "title": "Organic and solution processed tandem solar cells with 17.3% efficiency", "venue": "Science", "year": 2018 }, { "abstract": "Fabricating organic solar cells (OSCs) with a tandem structure has been considered an effective method to overcome the limited light absorption spectra of organic photovoltaic materials. Currently, the most efficient tandem OSCs are fabricated by adopting fullerene derivatives as acceptors. In this work, we designed a new non fullerene acceptor with an optical band gap (Egopt) of 1.68 eV for the front subcells and optimized the phase separation morphology of a fullerene free active layer with an Egopt of 1.36 eV to fabricate the rear subcell. The two subcells show a low energy loss and high external quantum efficiency, and their photoresponse spectra are complementary. In addition, an interconnection layer (ICL) composed of ZnO and a pH neutral self doped conductive polymer, PCP Na, with high light transmittance in the near IR range was developed. From the highly optimized subcells and ICL, solution processed fullerene free tandem OSCs with an average power conversion efficiency (PCE) greater than 13% were obtained.", "author_names": [ "Yong Cui", "Huifeng Yao", "Bowei Gao", "Yunpeng Qin", "Shaoqing Zhang", "Bei Yang", "Chang He", "Bowei Xu", "Jianhui Hou" ], "corpus_id": 326352, "doc_id": "326352", "n_citations": 350, "n_key_citations": 3, "score": 0, "title": "Fine Tuned Photoactive and Interconnection Layers for Achieving over 13% Efficiency in a Fullerene Free Tandem Organic Solar Cell.", "venue": "Journal of the American Chemical Society", "year": 2017 }, { "abstract": "We present a cost analysis based on state of the art printing and coating processes to fully encapsulated, flexible ITO and vacuum free polymer solar cell modules. Manufacturing data for both single junctions and tandem junctions are presented and analyzed. Within this calculation the most expensive layers and processing steps are identified. Based on large roll to roll coating experiments the exact material consumptions were determined. In addition to the data for the pilot scale experiment presented here, projections to medium and large scale scenarios serve as a guide to achieve cost targets of 5 EURct per Wp in a detailed material and cost analysis. These scenarios include the replacement of cost intensive layers, as well as process optimization steps. Furthermore, the cost structures for single and tandem devices are listed in detail and discussed. In an optimized model the material costs drop below 10 EUR per m2 which proves that OPV is a competitive alternative to established power generation technologies.", "author_names": [ "Florian Machui", "Markus Hosel", "Ning Li", "George D Spyropoulos", "Tayebeh Ameri", "Roar R Sondergaard", "Mikkel Jorgensen", "Arnulf Scheel", "Detlef Gaiser", "Kilian Kreul", "Daniel Lenssen", "Mathilde Legros", "Noella Lemaitre", "Marja Vilkman", "Marja K Valimaki", "Sirpa Nordman", "Christoph J Brabec", "Frederik C Krebs" ], "corpus_id": 95219272, "doc_id": "95219272", "n_citations": 143, "n_key_citations": 4, "score": 0, "title": "Cost analysis of roll to roll fabricated ITO free single and tandem organic solar modules based on data from manufacture", "venue": "", "year": 2014 }, { "abstract": "Inline printing and coating methods have been demonstrated to enable a high technical yield of fully roll to roll processed polymer tandem solar cell modules. We demonstrate generality by employing different material sets and also describe how the ink systems must be carefully co developed in order to reach the ambitious objective of a fully printed and coated 14 layer flexible tandem solar cell stack. The roll to roll methodologies involved are flexographic printing, rotary screen printing, slot die coating, X ray scattering, electrical testing and UV lamination. Their combination enables the manufacture of completely functional devices in exceptionally high yields. Critical to the ink and process development is a carefully chosen technology transfer to industry method where first a roll coater is employed enabling contactless stack build up, followed by a small roll to roll coater fitted to an X ray machine enabling in situ studies of wet ink deposition and drying mechanisms, ultimately elucidating how a robust inline processed recombination layer is key to a high technical yield. Finally, the transfer to full roll to roll processing is demonstrated.", "author_names": [ "Thomas R Andersen", "Henrik Friis Dam", "Markus Hosel", "Martin Helgesen", "Jon Eggert Carle", "Thue Trofod Larsen-Olsen", "S A Gevorgyan", "Jens Wenzel Andreasen", "Jens Adams", "Ning Li", "Florian Machui", "George D Spyropoulos", "Tayebeh Ameri", "Noella Lemaitre", "Mathilde Legros", "Arnulf Scheel", "Detlef Gaiser", "Kilian Kreul", "Stephane Berny", "O R Lozman", "Sirpa Nordman", "Marja K Valimaki", "Marja Vilkman", "Roar R Sondergaard", "Mikkel Jorgensen", "Christoph J Brabec", "Frederik C Krebs" ], "corpus_id": 96901794, "doc_id": "96901794", "n_citations": 195, "n_key_citations": 1, "score": 0, "title": "Scalable, ambient atmosphere roll to roll manufacture of encapsulated large area, flexible organic tandem solar cell modules", "venue": "", "year": 2014 }, { "abstract": "As single junction photovoltaic (PV) technologies, both Si heterojunction (HIT) and perovskite based solar cells promise high efficiencies at low cost. Intuitively, a traditional tandem cell design with these cells connected in series is expected to improve the efficiency further. Using a self consistent numerical modeling of optical and transport characteristics, however, we find that a traditional series connected tandem design suffers from low JSC due to band gap mismatch and current matching constraints. Specifically, a traditional tandem cell with state of the art HIT e=24% and perovskite e=20% sub cells provides only a modest tandem efficiency of eT~ 25% Instead, we demonstrate that a bifacial HIT/perovskite tandem design decouples the optoelectronic constraints and provides an innovative path for extraordinary efficiencies. In the bifacial configuration, the same state of the art sub cells achieve a normalized output of eT* 33% exceeding the bifacial HIT performance at practical albedo re.", "author_names": [ "Reza Asadpour", "Raghu Vamsi Krishna Chavali", "M Ryyan Khan", "Muhammad A Alam" ], "corpus_id": 109438804, "doc_id": "109438804", "n_citations": 62, "n_key_citations": 2, "score": 0, "title": "Bifacial Si heterojunction perovskite organic inorganic tandem to produce highly efficient eT* 33% solar cell", "venue": "", "year": 2015 }, { "abstract": "<jats:p><jats:fig position=\"anchor\"<jats:graphic xmlns:xlink=\"http:/www.w3.org/1999/xlink\" orientation=\"portrait\" mime subtype=\"jpeg\" mimetype=\"image\" position=\"float\" xlink:type=\"simple\" xlink:href=\"S0884291419001687_figAb\" /jats:fig>/jats:p>", "author_names": [ "Zenan Jiang", "Bobak Gholamkhass", "Peyman Servati" ], "corpus_id": 181358107, "doc_id": "181358107", "n_citations": 5, "n_key_citations": 1, "score": 0, "title": "Effects of interlayer properties on the performance of tandem organic solar cells with low and high band gap polymers", "venue": "Journal of Materials Research", "year": 2019 }, { "abstract": "Fabricating solar cells with tandem structure is an efficient way to broaden the photon response range without further increasing the thermalization loss in the system. In this work, a tandem organic solar cell (TOSC) based on highly efficient nonfullerene acceptors (NFAs) with series connection type is demonstrated. To meet the different demands of front and rear sub cells, two NFAs named F M and NOBDT with a whole absorption range from 300 to 900 nm are designed, when blended with wide bandgap polymer poly[(2,6 (4,8 bis(5 (2 ethylhexyl)thiophen 2 yl) benzo[1,2 b:4,5 b']dithiophene) alt (5,5 (1',3' di 2 thienyl 5',7' bis(2 ethylhexyl)benzo[1',2' c:4',5' c']dithiophene 4,8 dione) (PBDB T) and narrow bandgap polymer PTB7 Th, respectively, the PBDB T: F M system exhibits a high Voc of 0.98 V and the PTB7 Th: NOBDT system shows a remarkable Jsc of 19.16 mA cm 2 which demonstrate their potential in the TOSCs. With the guidance of optical simulation, by systematically optimizing the thickness of each layer in the TOSC, an outstanding power conversion efficiency of 14.11% with a Voc of 1.71 V, a Jsc of 11.72 mA cm 2 and a satisfactory fill factor of 0.70 is achieved; this result is one of the top efficiencies reported to date in the field of organic solar cells.", "author_names": [ "Yamin Zhang", "Bin Kan", "Yanna Sun", "Yanbo Wang", "Ruoxi Xia", "Xin Ke", "Yuan-Qiu-Qiang Yi", "Chenxi Li", "Hin-Lap Yip", "Xiangjian Wan", "Yong Cao", "Yongsheng Chen" ], "corpus_id": 4361721, "doc_id": "4361721", "n_citations": 136, "n_key_citations": 0, "score": 0, "title": "Nonfullerene Tandem Organic Solar Cells with High Performance of 14.11.", "venue": "Advanced materials", "year": 2018 }, { "abstract": "The great challenge to improve the performance of a tandem organic solar cell is how we can measure the true behavior of its individual sub cells. In this work, we develop a new architecture of the tandem solar cell to directly and accurately measure I V and quantum efficiency of the individual sub cells by using a very thin, semi transparent metal interlayer with different surface modification as anode and cathode. Separate measurements of reference cells are used in the conventional method to evaluate the contribution of every individual sub cell in a tandem structure. The discrepancy between the summations of two individual sub cells in a tandem device and the sum of conventional two reference cells is significant. This great discrepancy is mainly ascribed to the light trapping effect from the rough silver interlayer connection. This work demonstrates that direct measuring of individual sub cells in a tandem structure is the only way to evaluate the true contribution of each sub cell, thus having important impact on the study of fundamentals and on the improvement of tandem solar cells.", "author_names": [ "Hong Bin Yang", "Qunliang Song", "Chang Ming Li", "Zhisong Lu" ], "corpus_id": 97685804, "doc_id": "97685804", "n_citations": 20, "n_key_citations": 1, "score": 0, "title": "New architecture for accurate characterization of the behavior of individual sub cells within a tandem organic solar cell", "venue": "", "year": 2008 }, { "abstract": "Tandem type organic solar cell consisting of two combined unit cells was fabricated. Each unit cell was two layer organic solar cell composed of metal free phthalocyanine and perylene tetracarboxylic derivative. When ultra thin Au layer was inserted between unit cells, photovoltage increased about 2 times, while photocurrent density was much dependent on the thickness of the inserted Au layer.", "author_names": [ "Masahiro Hiramoto", "Minoru Suezaki", "Masaaki Yokoyama" ], "corpus_id": 94200787, "doc_id": "94200787", "n_citations": 185, "n_key_citations": 1, "score": 0, "title": "Effect of Thin Gold Interstitial layer on the Photovoltaic Properties of Tandem Organic Solar Cell", "venue": "", "year": 1990 }, { "abstract": "Abstract Tandem structures can boost the efficiency of organic solar cell to more than 15% compared to the 10% limit of single layer bulk heterojunction devices. Design and fabricating of intermediate layers plays a very important role to achieve high device performance. This article will review the main experimental progresses of tandem organic solar cells, and focus on the intermediate layers (charge recombination layers) in both thermal evaporated and solution processed organic tandem solar cell devices.", "author_names": [ "Yongbo Yuan", "Jinsong Huang", "Gang Li" ], "corpus_id": 96006, "doc_id": "96006", "n_citations": 44, "n_key_citations": 1, "score": 0, "title": "Intermediate Layers in Tandem Organic Solar Cells", "venue": "", "year": 2011 } ]

[ { "abstract": "Metal halide perovskites are mixed electronic ionic semiconductors with an extraordinarily rich optoelectronic behavior and the capability to function very efficiently as active layers in solar cells, with a record efficiency surpassing 23% nowadays. In this work, we carry out an impedance spectroscopy analysis of two perovskite solar cells with quite distinct optical and electrical characteristics, i.e. MAPbI3 and CsPbBr3 based devices. The main aim of the analysis is to establish how, regardless of the inherent complexity of the impedance spectrum due to ionic effects, information like ideality factors, recombination losses and the collection efficiency can be qualitatively and quantitatively assessed from impedance experiments under operating conditions.", "author_names": [ "Lidia Contreras-Bernal", "Susana Ramos-Terron", "Antonio J Riquelme", "Pablo P Boix", "Jesus Idigoras", "Ivan Mora-Sero", "Juan Antonio Anta" ], "corpus_id": 146106109, "doc_id": "146106109", "n_citations": 51, "n_key_citations": 0, "score": 1, "title": "Impedance analysis of perovskite solar cells: a case study", "venue": "", "year": 2019 }, { "abstract": "We fabricated perovskite quantum dot solar cells (PQDSCs) and varied the thickness of the QD layer by controlling the number of deposition cycles; the cells were systematically investigated with impedance spectroscopy. Despite the evident structural differences with respect to standard perovskite solar cells (PSCs) similar impedance spectra were obtained for PQDSCs, pointing to similar working principles in terms of the active layer. We distinguish two different regimes: At low illumination, recombination is ruled by multiple trapping with trap distributions and/or shunting. However, at higher light intensities, Shockley Read Hall recombination is observed. In addition, the low frequency capacitance, CLF, of PQDSCs increases several orders of magnitude when the illumination is varied from dark to 1 sun conditions. This feature has not been observed in other kinds of photovoltaic devices and is characteristic of PSCs. Although there is no consensus about the exact mechanism responsible for CLF, the sugges.", "author_names": [ "Zahra Zolfaghari", "Ehsan Hassanabadi", "Didac Pitarch-Tena", "Seog Joon Yoon", "Zahra Shariatinia", "Jao van de Lagemaat", "Joseph M Luther", "Ivan Mora-Sero" ], "corpus_id": 139185990, "doc_id": "139185990", "n_citations": 45, "n_key_citations": 0, "score": 0, "title": "Operation Mechanism of Perovskite Quantum Dot Solar Cells Probed by Impedance Spectroscopy", "venue": "", "year": 2019 }, { "abstract": "Perovskite solar cells are notorious for exhibiting transient behaviour not seen in conventional inorganic semiconductor devices. Significant inroads have been made into understanding this fact in terms of rapid ion migration, now a well established property of the prototype photovoltaic perovskite MAPbI$_3$ and strongly implicated in the newer mixed compositions. Here we study the manifestations of ion migration in frequency domain small signal measurements, focusing on the popular technique of Electrical Impedance Spectroscopy (EIS) We provide new interpretations for a variety of previously puzzling features, including giant photo induced low frequency capacitance and negative capacitance in a variety of forms. We show that these apparently strange measurements can be rationalized by the splitting of AC current into two components, one associated with charge storage, and the other with the quasi steady state recombination current of electrons and holes. The latter contribution to the capacitance can take either a positive or a negative sign, and is potentially very large when slow, voltage sensitive processes such as ion migration are at play. Using numerical drift diffusion semiconductor models, we show that giant photo induced capacitance, inductive loop features, and low frequency negative capacitance all emerge naturally as consequences of ion migration via its coupling to quasi steady state electron and hole currents. In doing so, we unify the understanding of EIS measurements with the comparably well developed theory of rate dependent current voltage (I V) measurements in perovskite cells. Comparing the two techniques, we argue that EIS is more suitable for quantifying I V hysteresis than conventional methods based on I V sweeps, and demonstrate this application on a variety of cell types.", "author_names": [ "Daniel A Jacobs", "Heping Shen", "Florian Pfeffer", "Jun Peng", "Thomas P White", "Fiona J Beck", "Kylie R Catchpole Research School of Engineering", "The Australian National University", "" ], "corpus_id": 53455518, "doc_id": "53455518", "n_citations": 56, "n_key_citations": 0, "score": 0, "title": "The Two Faces of Capacitance: New Interpretations for Electrical Impedance Measurements of Perovskite Solar Cells and Their Relation to Hysteresis", "venue": "", "year": 2018 }, { "abstract": "Abstract The ubiquitous hysteresis in the current voltage characteristic of perovskite solar cells (PSCs) interferes in a proper determination of the diode ideality factor n a key parameter commonly adopted to analyze recombination mechanisms. An alternative way of determining n is by measuring the voltage variation of the ac resistances in conditions of negligible steady state dc currents. A reliable analysis of n based on the determination of the resistive response, free of hysteretic influences, reveals two separated voltage exponential dependences using different perovskite absorbers (3D perovskites layer based on CH3NH3PbI3 or mixed Cs0.1FA0.74MA0.13PbI2.48Br0.39) and a variety of interlayers (2D perovskite thin capping) The dominant resistive element always exhibits an exponential dependence with factor n 2 irrespective of the type of perovskite and capping layers. In addition, a non negligible resistive mechanism occurs at low frequencies (with voltage independent time constant 1 s) which is related to the kinetic properties of the outer interfaces, with varying ideality factor n 2 for CH3NH3PbI3, and n 1.5 for Cs0.1FA0.74MA0.13PbI2.48Br0.39) Our work identifies common features in the carrier recombination mechanisms among different types of high efficiency PSCs, and simultaneously signals particularities on specific architectures, mostly in the carrier dynamics at outer interfaces.", "author_names": [ "Osbel Almora", "Kyung Taek Cho", "Sadig Aghazada", "Iwan Zimmermann", "Gebhard J Matt", "Christoph J Brabec", "Mohammad Khaja Nazeeruddin", "Germa Garcia-Belmonte" ], "corpus_id": 103314125, "doc_id": "103314125", "n_citations": 60, "n_key_citations": 0, "score": 0, "title": "Discerning recombination mechanisms and ideality factors through impedance analysis of high efficiency perovskite solar cells", "venue": "", "year": 2018 }, { "abstract": "Mobile ions in hybrid perovskite semiconductors introduce a new degree of freedom to electronic devices suggesting applications beyond photovoltaics. An intuitive device model describing the interplay between ionic and electronic charge transfer is needed to unlock the full potential of the technology. We describe the perovskite contact interfaces as transistors which couple ionic charge redistribution to energetic barriers controlling electronic injection and recombination. This reveals an amplification factor between the out of phase electronic current and the ionic current. Our findings suggest a strategy to design thin film electronic components with large, tuneable, capacitor like and inductor like characteristics. The resulting simple equivalent circuit model, which we verified with time dependent drift diffusion simulations of measured impedance spectra, allows a general description and interpretation of perovskite solar cell behaviour.", "author_names": [ "Davide Moia", "Ilario Gelmetti", "Philip Calado", "William Fisher", "Michael Stringer", "Onkar S Game", "Yinghong Hu", "Pablo Docampo", "David G Lidzey", "Emilio Jose Palomares", "Jenny Nelson", "Piers R F Barnes" ], "corpus_id": 51681089, "doc_id": "51681089", "n_citations": 57, "n_key_citations": 0, "score": 0, "title": "Ionic to electronic current amplification in hybrid perovskite solar cells: ionically gated transistor interface circuit model explains hysteresis and impedance of mixed conducting devices", "venue": "", "year": 2018 }, { "abstract": "The partial replacement of methylammonium by formamidinium and cesium in organolead trihalide materials is of great importance to improve the performance and stability of photovoltaic solar cells. However, the effect of multiple cations on the cell functioning and their electrical characteristics remains to be clarified. By using the impedance spectroscopy technique, we have investigated the electrical response to a small ac perturbation applied to solar cells implementing hybrid perovskites with various compositions, polarized over a large potential range. The solar cell preparation protocols have been optimized to reach power conversion efficiencies higher than 17% The impedance response has been investigated both under light and in the dark to discriminate the light sensitive parameters. The spectra have been carefully analyzed using an ad hoc equivalent circuit, and the data have been discussed in the light of the existing literature. The spectra showed no intermediate frequency inductive loop due to.", "author_names": [ "Pengjiu Wang", "Maria Ulfa", "Thierry Pauporte" ], "corpus_id": 104172175, "doc_id": "104172175", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Effects of Perovskite Monovalent Cation Composition on the High and Low Frequency Impedance Response of Efficient Solar Cells", "venue": "", "year": 2018 }, { "abstract": "", "author_names": [ "Didac Pitarch-Tena", "Thi Tuyen Ngo", "Marta Valles-Pelarda", "Thierry Pauporte", "Ivan Mora-Sero" ], "corpus_id": 139212667, "doc_id": "139212667", "n_citations": 51, "n_key_citations": 0, "score": 0, "title": "Impedance Spectroscopy Measurements in Perovskite Solar Cells: Device Stability and Noise Reduction", "venue": "", "year": 2018 }, { "abstract": "Dye sensitized solar cells (DSCs) have emerged in the photovoltaic scenario as one of the most promising low cost alternative to the most employed solar devices based on silicon, especially for some niche application. Despite of the huge work carried out by scientists and researchers, detailed mechanism of some of the charge transfer processes occurring inside DSCs is not still fully understood. Electrochemical impedance spectroscopy (EIS) gave an immense help in analyzing these processes, and has been widely employed in the DSCs to characterize novel materials and architectures. The scope of this Review is to provide an insight on the application of EIS for the study of DSCs. A general introduction of the technique will be given, followed by an in depth review of its application in the DSC field. Finally, a brief discussion of future research directions concerning this topic will be presented.", "author_names": [ "Adriano Sacco" ], "corpus_id": 114284557, "doc_id": "114284557", "n_citations": 118, "n_key_citations": 6, "score": 0, "title": "Electrochemical impedance spectroscopy: Fundamentals and application in dye sensitized solar cells", "venue": "", "year": 2017 }, { "abstract": "The analysis of perovskite solar cells by impedance spectroscopy has provided a rich variety of behaviors that demand adequate interpretation. Two main features have been reported: First, different impedance spectral arcs vary in combination; second, inductive loops and negative capacitance characteristics appear as an intrinsic property of the current configuration of perovskite solar cells. Here we adopt a previously developed surface polarization model based on the assumption of large electric and ionic charge accumulation at the external contact interface. Just from the equations of the model, the impedance spectroscopy response is calculated and explains the mentioned general features. The inductance element in the equivalent circuit is the result of the delay of the surface voltage and depends on the kinetic relaxation time. The model is therefore able to quantitatively describe exotic features of the perovskite solar cell and provides insight into the operation mechanisms of the device.", "author_names": [ "Elnaz Ghahremanirad", "Agustin Bou", "Saeed Olyaee", "Juan Bisquert" ], "corpus_id": 3848937, "doc_id": "3848937", "n_citations": 73, "n_key_citations": 0, "score": 0, "title": "Inductive Loop in the Impedance Response of Perovskite Solar Cells Explained by Surface Polarization Model.", "venue": "The journal of physical chemistry letters", "year": 2017 }, { "abstract": "Mesoscopic solid state solar cells based on the inorganic organic hybrid perovskite CH3NH3PbI3 in conjunction with the amorphous organic semiconductor spiro MeOTAD as a hole transport material (HTM) are investigated using impedance spectroscopy (IS) A model to interpret the frequency response of these devices is established by expanding and elaborating on the existing models used for the liquid and solid state dye sensitized solar cells. Furthermore, the influence of changing the additive concentrations of tert butylpyridine and LiTFSI in the HTM and varying the HTM overlayer thickness on top of the sub micrometer thick TiO2 on the extracted IS parameters is investigated. The internal electrical processes of such devices are studied and correlated with the overall device performance. In particular, the features in the IS responses that are attributed to the ionic and electronic transport properties of the perovskite material and manifest as a slow response at low frequency and an additional RC element at intermediate frequency, respectively, are explored.", "author_names": [ "Amalie Dualeh", "Thomas Moehl", "Nicolas Tetreault", "Joel Teuscher", "Peng Gao", "Mohammad Khaja Nazeeruddin", "Michael Gratzel" ], "corpus_id": 5409494, "doc_id": "5409494", "n_citations": 564, "n_key_citations": 5, "score": 0, "title": "Impedance spectroscopic analysis of lead iodide perovskite sensitized solid state solar cells.", "venue": "ACS nano", "year": 2014 } ]

[ { "abstract": "The development of scalable sources of non classical light is fundamental to unlocking the technological potential of quantum photonics. Semiconductor quantum dots are emerging as near optimal sources of indistinguishable single photons. However, their performance as sources of entangled photon pairs are still modest compared to parametric down converters. Photons emitted from conventional Stranski Krastanov InGaAs quantum dots have shown non optimal levels of entanglement and indistinguishability. For quantum networks, both criteria must be met simultaneously. Here, we show that this is possible with a system that has received limited attention so far: GaAs quantum dots. They can emit triggered polarization entangled photons with high purity (g(2)(0) 0.002+ 0.002) high indistinguishability (0.93+ 0.07 for 2 ns pulse separation) and high entanglement fidelity (0.94+ 0.01) Our results show that GaAs might be the material of choice for quantum dot entanglement sources in future quantum technologies.", "author_names": [ "Daniel Huber", "Marcus Reindl", "Yongheng Huo", "Huiying Huang", "Johannes S Wildmann", "Oliver G Schmidt", "Armando Rastelli", "Rinaldo Trotta" ], "corpus_id": 36149189, "doc_id": "36149189", "n_citations": 153, "n_key_citations": 3, "score": 1, "title": "Highly indistinguishable and strongly entangled photons from symmetric GaAs quantum dots", "venue": "Nature communications", "year": 2017 }, { "abstract": "The generation and long haul transmission of highly entangled photon pairs is a cornerstone of emerging photonic quantum technologies, with key applications such as quantum key distribution and distributed quantum computing. However, a natural limit for the maximum transmission distance is inevitably set by attenuation in the medium. A network of quantum repeaters containing multiple sources of entangled photons would allow to overcome this limit. For this purpose, the requirements on the source's brightness and the photon pairs' degree of entanglement and indistinguishability are stringent. Despite the impressive progress made so far, a definitive scalable photon source fulfilling such requirements is still being sought for. Semiconductor quantum dots excel in this context as sub poissonian sources of polarization entangled photon pairs. In this work we present the state of the art set by GaAs based quantum dots and use them as a benchmark to discuss the challenges to overcome towards the realization of practical quantum networks.", "author_names": [ "Christian Schimpf", "Marcus Reindl", "Francesco Basso Basset", "Klaus D Jons", "Rinaldo Trotta", "Armando Rastelli" ], "corpus_id": 227162156, "doc_id": "227162156", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Quantum dots as potential sources of strongly entangled photons for quantum networks", "venue": "", "year": 2020 }, { "abstract": "Semiconductor quantum dots are converging towards the demanding requirements of photonic quantum technologies. Among different systems, quantum dots with dimensions exceeding the free exciton Bohr radius are appealing because of their high oscillator strengths. While this property has received much attention in the context of cavity quantum electrodynamics, little is known about the degree of indistinguishability of single photons consecutively emitted by such dots and on the proper excitation schemes to achieve high indistinguishability. A prominent example is represented by GaAs quantum dots obtained by local droplet etching, which recently outperformed other systems as triggered sources of entangled photon pairs. On these dots, we compare different single photon excitation mechanisms, and we find (i) a \"phonon bottleneck\" and poor indistinguishability for conventional excitation via excited states and (ii) photon indistinguishablilities above 90% for both strictly resonant and for incoherent acoustic and optical phonon assisted excitation. Among the excitation schemes, optical phonon assisted excitation enables straightforward laser rejection without a compromise on the source brightness together with a high photon indistinguishability.", "author_names": [ "Marcus Reindl", "J Weber", "Daniel Huber", "Christian Schimpf", "Saimon Filipe Covre da Silva", "Simone Luca Portalupi", "Rinaldo Trotta", "Peter Michler", "Armando Rastelli" ], "corpus_id": 119249128, "doc_id": "119249128", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Highly indistinguishable single photons from incoherently excited quantum dots", "venue": "Physical Review B", "year": 2019 }, { "abstract": "The generation and long haul transmission of highly entangled photon pairs is a cornerstone of emerging photonic quantum technologies with key applications such as quantum key distribution and distributed quantum computing. However, a natural limit for the maximum transmission distance is inevitably set by attenuation in the medium. A network of quantum repeaters containing multiple sources of entangled photons would allow overcoming this limit. For this purpose, the requirements on the source's brightness and the photon pairs' degree of entanglement and indistinguishability are stringent. Despite the impressive progress made so far, a definitive scalable photon source fulfilling such requirements is still being sought after. Semiconductor quantum dots excel in this context as sub Poissonian sources of polarization entangled photon pairs. In this work, we present the state of the art set by GaAs based quantum dots and use them as a benchmark to discuss the challenges toward the realization of practical quantum networks.", "author_names": [ "Christian Schimpf", "Marcus Reindl", "Francesco Basso Basset", "Klaus D Jons", "Rinaldo Trotta", "Armando Rastelli" ], "corpus_id": 233617353, "doc_id": "233617353", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Quantum dots as potential sources of strongly entangled photons: Perspectives and challenges for applications in quantum networks", "venue": "", "year": 2021 }, { "abstract": "Semiconductor quantum dots (QDs) obtained by epitax ial growth are regarded as one of the most promisin g olid state sources of triggered single and entangled photons f r applications in emerging quantum technologies. While most of the studies presented so far have mos tly focused on InGaAs/GaAs QDs obtained by the Stra nskiKrastanow (SK) growth mode, GaAs QDs in AlGaAs matr ix have emerged as a promising alternative to SK QD s. In this talk I will begin by briefly discussing the growth of GaAs QDs with highly symmetric shape [1 using two independent molecular beam epitaxy machines. I will the n present recent results on the generation of polar ization entangled photons from such dots [2] The good degree of ind istinguishability of the emitted photons recently a lowed us to perform two photon interference experiments using two inde pendent QDs [3] For this experiment the emission energy of one of the QDs was finely tuned by piezoelectric induced strai n. Finally I will show that the addition of strain after growth allows us to substantially modify the nature of confined holes i n a QD, which results in novel selection rules. In particular, uniaxial stress allows the quantization axis of the QD to be reorie nted in the growth plane [4] a configuration parti cularly suitable for integrated quantum photonics applications.", "author_names": [ "Armando Rastelli" ], "corpus_id": 221948325, "doc_id": "221948325", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Droplet etched GaAs/AlGaAs quantum dots for quantum photonics applications", "venue": "", "year": 2018 }, { "abstract": "A semiconductor quantum dot (QD) can generate highly indistinguishable single photons at a high rate. For application in quantum communication and integration in hybrid systems, control of the QD optical properties is essential. Understanding the connection between the optical properties of a QD and the growth process is therefore important. Here, we show for GaAs QDs, grown by infilling droplet etched nanoholes, that the emission wavelength, the neutral to charged exciton splitting, and the diamagnetic shift are strongly correlated with the capture zone area, an important concept from nucleation theory. We show that the capture zone model applies to the growth of this system even in the limit of a low QD density in which atoms diffuse over \\ensuremath{\\mu}\\mathrm{m} distances. The strong correlations between the various QD parameters facilitate preselection of QDs for applications with specific requirements on the QD properties; they also suggest that a spectrally narrowed QD distribution will result if QD growth on a regular lattice can be achieved.", "author_names": [ "Matthias Christian Lobl", "Liang-Jun Zhai", "Jan-Philipp Jahn", "Julian Ritzmann", "Yongheng Huo", "Andreas Dirk Wieck", "Oliver G Schmidt", "Arne Ludwig", "Armando Rastelli", "Richard John Warburton" ], "corpus_id": 119443529, "doc_id": "119443529", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Correlations between optical properties and Voronoi cell area of quantum dots", "venue": "Physical Review B", "year": 2019 }, { "abstract": "Introduction Semiconductor quantum dot (QD) is one of the promising candidates for on demand entangled photon emitters. To realize the entangled photon emission on the polarization basis, formation of laterally symmetric QDs are essentially necessary. By using GaAs (111)A surface with three fold rotational symmetry, we have realized highly symmetric GaAs QDs/AlGaAs by droplet epitaxy [1] which generate high quality entangled photon with filtering free violation of Bell's inequality [2] Previously, we have used optical excitation for the entangled photon generation. In this study, we report the formation of light emitting diodes (LED) that generate entangled photons by current injection, which is an important step for practical device applications. Experimental The sample was grown on nGaAs(111)A by solid source molecular beam epitaxy. After the growth of 50 nm n GaAs (Si: 1 x 10 cm) 100 nm n Al0.32Ga0.68As (Si: 5 x 10 cm) 20 nm Al0.33Ga0.67As, and 100 nm Al0.28Ga0.72As at 510 degC, GaAs QDs were formed by droplet epitaxy. To form the QDs, 0.05 monolayers (ML) gallium (0.01 ML/s) were supplied at 450 degC. Then, an As4 flux (5 x 10 Torr) was supplied at 200 degC for crystallization, followed by annealing at 500 degC. The QDs were capped with 100 nm Al0.28Ga0.72As and 25 nm Al0.33Ga0.67As at 510 degC. Then, a 100 nm p Al0.33Ga0.67As (Si: 5 x 10 cm) 20 nm p Al0.33Ga0.67As (Si: 2 x 10 cm) and 20 nm p GaAs (Si: 2 x 10 cm) were grown at 580 degC. For the growth of n type (and undoped) and p type layers, high (7 x 10 Torr) and low (6 x 10 Torr) As4 fluxes were used, respectively, to control the Si doping sites. After the growth, bottom (Au/Ni/AuGe) and top (Au/Pt/Ti) contact electrodes were formed, followed by annealing at 350degC. The electroluminescence was obtained from the 10 x 10mm apertures formed in the top contact electrode. Results and Discussions The I V curve of the sample revealed a diode type asymmetric response. We applied a forward bias, so that the electroluminescence intensity reaches the saturation value. Figure 1(a) shows coincidence histograms for the biexcitonic photons (XX) and the excitonic photons (X) with circular polarizations setting. The presence of a central peak for cross circular polarization confirms a higher probability than that for detecting uncorrelated photons. The central peak disappears for co circular polarization. Figure 1(b) shows coincidence histograms for linear polarizations setting. A positive correlation appears for the parallel polarization, while it disappears for the orthogonal polarizations. The XX and X photons are clearly correlated in any polarization basis, which is a rigorous proof for the formation of quantum entanglement. [1] T. Mano et al. Appl. Phys. Express 3, 065203 (2010) [2] T. Kuroda et al. Phys. Rev. B 88, 041306(R) (2013) Fig. 1 Coincidence histogram between excitons and biexciton photons for different polarization combinations. 500", "author_names": [ "Neul Ha", "Takaaki Mano", "Yoshiki Sakuma", "Kazuaki Sakoda", "Takashi Kuroda" ], "corpus_id": 126136335, "doc_id": "126136335", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Entangled photon emitting diode based on GaAs droplet quantum dots", "venue": "", "year": 2016 }, { "abstract": "Entangled photons are efficiently generated from highly symmetric, site controlled InGaAs/GaAs quantum dots grown in inverted pyramids. Fine structure splitting of the intermediate exciton level is suppressed without the application of electric, magnetic or strain fields. Polarization entanglement is demonstrated by measurements of the two photon density matrix and the confirmation of several entanglement criteria.", "author_names": [ "Aneena Mohan", "Marco Felici", "Pascal Gallo", "Benjamin Dwir", "Alok P Rudra", "Jerome Faist", "E Kapon" ], "corpus_id": 123176514, "doc_id": "123176514", "n_citations": 140, "n_key_citations": 1, "score": 0, "title": "Polarization entangled photons produced with high symmetry site controlled quantum dots", "venue": "", "year": 2010 }, { "abstract": "To generate entangled photon pairs via quantum dots (QDs) the exciton fine structure splitting (FSS) must be comparable to the exciton homogeneous line width. Yet in the (In,Ga)As/GaAs QD, the intrinsic FSS is about a few tens meV. To achieve photon entanglement, it is necessary to Cherrypick a sample with extremely small FSS from a large number of samples, or to apply strong in plane magnetic field. Using theoretical modeling of the fundamental causes of FSS in QDs, we predict that the intrinsic FSS of InAs/InP QDs is an order of magnitude smaller than that of InAs/GaAs dots, and better yet, their excitonic gap matches the 1.55 mm fiber optic wavelength, therefore offer efficient on demand entangled photon emitters for long distance quantum communication.", "author_names": [ "Lixin He", "Ming Gong", "Chuan-Feng Li", "Guangcan Guo", "Alex Zunger" ], "corpus_id": 59327012, "doc_id": "59327012", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "J un 2 00 8 Highly reduced Fine structure splitting in InAs InP quantum dots offering efficient on demand 1 55 m m entangled photon emitter", "venue": "", "year": 2018 }, { "abstract": "The generation of high quality entangled photon pairs has been a long sought goal in modern quantum communication and computation. So far, the most widely used entangled photon pairs have been generated from spontaneous parametric down conversion (SPDC) a process that is intrinsically probabilistic and thus relegated to a regime of low rates of pair generation. In contrast, semiconductor quantum dots can generate triggered entangled photon pairs through a cascaded radiative decay process and do not suffer from any fundamental trade off between source brightness and multi pair generation. However, a source featuring simultaneously high photon extraction efficiency, high degree of entanglement fidelity and photon indistinguishability has been lacking. Here, we present an entangled photon pair source with high brightness and indistinguishability by deterministically embedding GaAs quantum dots in broadband photonic nanostructures that enable Purcell enhanced emission. Our source produces entangled photon pairs with a pair collection probability of up to 0.65(4) (single photon extraction efficiency of 0.85(3) entanglement fidelity of 0.88(2) and indistinguishabilities of 0.901(3) and 0.903(3) (brackets indicate uncertainty on last digit) This immediately creates opportunities for advancing quantum photonic technologies.Embedding GaAs quantum dots in broadband photonic nanostructures allows a source of entangled photons to be fabricated with simultaneous enhancements of the most important parameters.", "author_names": [ "Jin Liu", "Rongbin Su", "Yuming Wei", "Beimeng Yao", "Saimon Filipe Covre da Silva", "Ying Yu", "Jake Iles-Smith", "Kartik Srinivasan", "Armando Rastelli", "Juntao Li", "Xuehua Wang" ], "corpus_id": 92988265, "doc_id": "92988265", "n_citations": 154, "n_key_citations": 2, "score": 0, "title": "A solid state source of strongly entangled photon pairs with high brightness and indistinguishability", "venue": "Nature Nanotechnology", "year": 2019 } ]

[ { "abstract": "The maximum ranging distance is a key technical indicator of the pulse laser range finder. It is generally obtained by testing the laser receiving sensitivity of the pulse laser range finder in the laboratory.The existing laser receiving sensitivity test is mainly realized by means of laser analog radiation source and collimating optical system.The laser radiation simulator generally uses a semiconductor laser to transmit the analog laser receiving signal to the focal plane of the collimating optical system through fiber coupling, and then radiates to the receiving aperture of the pulse laser range finder through the collimating optical system. Adjust the intensity of the laser to simulate the energy of the radiation source, and complete the test of the minimum detectable energy, that is, the laser receiving sensitivity.In the actual use process, it is found that the time stability deviation of the radiation power of the semiconductor laser in low power operation can reach 20% which is difficult to meet the requirements of use, and after the fiber coupling, the collimation of the collimating optical system, the radiation uniformity is difficult to fulfil requirements.Based on this, this paper designs a pulse laser range finder receiving sensitivity test equipment based on integrating sphere. The system uses the traditional laser radiation analog source plus attenuator to stabilize the laser radiation source.In the case of a pulsed laser range finder as a sensor in combination with a television or infrared sensor, a tungsten halogen lamp is added inside the integrating sphere to provide infrared or television target simulation,then the optical axis of the pulsed laser range finder and collimating optics can be quickly aligned.", "author_names": [ "Fei Xie", "Guofeng Zheng", "Baolin Du", "Peng Zhang" ], "corpus_id": 218798598, "doc_id": "218798598", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design of receiving sensitivity test system for pulse laser range finder based on integrating sphere", "venue": "", "year": 2020 }, { "abstract": "Abstract In order to suppress the effects of common mode noise, laser ranging and three dimensional imaging systems based on the differential optical path method (DOPM) are proposed. Compared with the traditional method based on single receiver, DOPM uses two receivers which have different optical paths. Based on DOPM, we developed the laser ranging and three dimensional (3D) imaging systems and carried out ranging and three dimensional imaging experiments to research DOPM for practical application. In ranging experiments, the root mean square (RMS) of ranging error decreases from 95 to 70 mm; as a result the error could be decreased to 74% of the method based on a single receiver. Meanwhile, the system obtains the highest sensitivity when differential distance is multiplied by light speed and receiving pulse width. In 3D imaging experiments, compared with the traditional method, the mean RMS of 64 channels based on DOPM decreases from 99 to 65 mm, which decreases to 66% Meanwhile, DOPM improves the range resolution and could distinguish two targets with height difference of 80 mm.", "author_names": [ "Hao Qun", "Cao Jie", "Hu Yao", "Mu Jiaxing", "Xu Jianchun", "Zhai Zichao", "Chen Pin" ], "corpus_id": 124038774, "doc_id": "124038774", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Laser ranging and three dimensional imaging systems based on the differential optical path method", "venue": "", "year": 2016 }, { "abstract": "In this paper, the key technologies of single photon detection in airborne laser ranging are analyzed. Aiming at the engineering application, we propose the next investigation of single photon detection. 1) the compensation of pulse propagation in atmosphere; 2) the problem of ranging accuracy for moving targets; 3) high accuracy optical axis coherence of receiving and transmitting. Further research can improve the airborne adaptability of single photon ranging system.", "author_names": [ "Jie Fu", "Baolin Du", "Dezhao Zhou", "Lei Li", "Yi Yang" ], "corpus_id": 126058522, "doc_id": "126058522", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Researching on single photon detection in airborne laser ranging", "venue": "Other Conferences", "year": 2018 }, { "abstract": "Using the penetration of blue green band (532 nm) laser in seawater, airborne laser scanning ranging technology can be applied to shallow sea measurements. The penetration properties of lasers due to the complex optical properties of seawater are also limited. The decrease of echo energy received by the sensor will greatly limit the accuracy of laser seabed survey. In response to this phenomenon, we propose a new structural design method combined with the optimal field of view (FOV) for shallow sea measurements to optimize the traditional receiving system to improve the laser receiving depth echo signal receiving capability. The simulation experiment is carried out by ZEMAX optical software. Experimental results show that the improved receiving system can effectively reduce spherical aberration and coma caused by spherical lens, and improve the imaging quality of the receiving system and the measurement accuracy of the shallow seabed.", "author_names": [ "Guoqing Zhou", "Jiandong Wei", "Xiaoping Zhou", "Wei Huang", "Jian Jhen Chen", "Yizhi Tan", "HaochengHu Wei" ], "corpus_id": 208039928, "doc_id": "208039928", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Structural Optimization of Receiving System Based on Optimal Field of View for Shallow Sea Laser Measurement", "venue": "IGARSS 2019 2019 IEEE International Geoscience and Remote Sensing Symposium", "year": 2019 }, { "abstract": "Abstract We are reporting on identification and calibration of one way delays in satellite laser ranging systems. Satellite Laser Ranging (SLR) is a standard technique to measure the distance of satellites as a function of time with millimeter precision and a few millimeters accuracy. For one way laser ranging, laser time transfer ground to space and for bi and multi static laser ranging to space objects identification and measurement of system delays related separately to transmitting and receiving parts of the system are needed. The epochs of transmission and reception of optical signals have to be referred to the coordinated time scale with the accuracy reaching one nanosecond level or better for one way ranging and space debris multi static ranging. For transponder ranging and laser time transfer an even higher accuracy of 50 ps or better is needed. These accuracy requirements are by several orders of magnitude higher in comparison to standard SLR applications. A new procedure of calibration of one way delays related to the SLR systems has been developed and tested. The necessary hardware components needed for calibration measurements were designed and developed in a form of a Calibration Device. It consists of a photon counting detector, an epoch timing device and a dedicated signal cable. The signal propagation delays of these components were determined with an accuracy of better than 20 ps. The signal propagation delay stability of the Calibration Device is on a level of units of picoseconds over days of operation. The Calibration Device and calibration procedure were tested in real measurements at the SLR site in Graz, Austria. The time needed to complete a calibration of one way delays of the SLR system is less than two days. The one way system delays were determined with the accuracy better than 50 ps. The measurement principle, Calibration Device and the first results are presented.", "author_names": [ "Ivan Prochazka", "Jan Kodet", "Josef Blazej", "Georg Kirchner", "Franz Koidl", "Peiyuan Wang" ], "corpus_id": 113933219, "doc_id": "113933219", "n_citations": 6, "n_key_citations": 1, "score": 1, "title": "Identification and calibration of one way delays in satellite laser ranging systems", "venue": "", "year": 2017 }, { "abstract": "The invention discloses a multielement photon counting laser ranging three dimensional imaging system. The system comprises a laser emitting unit used for emitting beam arrays, a control unit for controlling the beam arrays to be emitted and scanned, a receiving and detecting unit which receives echo optical signals through an optical lens and detects focal plane optical signals through a single photon detector array formed by coupling optical fiber arrays, and a time measurement unit used for recording and analyzing multi channel photon flying time. According to multielement photon counting three dimensional imaging system, the single photon detector array formed by coupling optical fiber arrays is used, multielement photon counting laser ranging of one dimensional laser beam arrays is achieved, one dimensional scanning is performed on the beam arrays in the vertical direction of arrangement of the beam arrays, and photon counting three dimensional laser imaging is achieved.", "author_names": [ "" ], "corpus_id": 141352909, "doc_id": "141352909", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Multielement photon counting laser ranging three dimensional imaging system", "venue": "", "year": 2014 }, { "abstract": "Satellite Laser Raging (SLR) System in Fangshan SLR station had been low sensitivity in receiving the returns from the satellite for a quite long time and no good adoption for the data by users. Some designs and rebuilding work were made to increase the sensitivity for the ranging and the monitoring ability of the ICCD in the optical receiving system of the SLR system described in the paper. The results were satisfied according to the data analysis reports of Delft Orbital Analysis, a SLR data analysis center of International Laser ranging service (ILRS)", "author_names": [ "Cheng Bo-hui" ], "corpus_id": 130569451, "doc_id": "130569451", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Rebuilding for optical system in satellite laser ranging system", "venue": "", "year": 2007 }, { "abstract": "In the performance test of the satellite based laser ranging system equipment on earth,optical pulse for simulating distance with high precision,stable and adjustable were needed,then the adjustable distance simulation technology was developed.A adjustable distance simulation system consisting of laser receiving,delay control,high precision signal delay and laser emitting units is designed to simulate distance.The minimum simulation distance of the adjustable distance simulator achiev 15 m,the accuracy superior 0.15 m are proved by experiments,satisfing the demands of the performance test of all kinds of satellite based laser ranging system equipment on earth by now.", "author_names": [ "Shu Rong" ], "corpus_id": 111770222, "doc_id": "111770222", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design of a Adjustable Distance Simulator for Pulsed Laser Ranging System Equipment", "venue": "", "year": 2012 }, { "abstract": "ARGO M is a satellite laser ranging (SLR) system developed by the Korea Astronomy and Space Science Institute with the consideration of mobility and daytime and nighttime satellite observation. The ARGO M optical system consists of 40 cm receiving telescope, 10 cm transmitting telescope, and detecting optics. For the development of ARGO M optical system, the structural analysis was performed with regard to the optics and optomechanics design and the optical components. To ensure the optical performance, the quality was tested at the level of parts using the laser interferometer and ultra high precision measuring instruments. The assembly and alignment of ARGO M optical system were conducted at an auto collimation facility. As the transmission and reception are separated in the ARGO M optical system, the pointing alignment between the transmitting telescope and receiving telescope is critical for precise target pointing. Thus, the alignment using the ground target and the radiant point observation of transmitting laser beam was carried out, and the lines of sight for the two telescopes were aligned within the required pointing precision. This paper describes the design, structural analysis, manufacture and assembly of parts, and entire process related with the alignment for the ARGO M optical system.", "author_names": [ "Jakyoung Nah", "Jung-Guen Jang", "B H Jang", "Inwoo Han", "Jeong-Yeol Han", "Kwijong Park", "Hyung-Chul Lim", "Sung-Yeol Yu", "Eunseo Park", "Y K Seo", "Il K Moon", "Byung-Kyu Choi", "Eunjoo Na", "Uk-won Nam" ], "corpus_id": 120270399, "doc_id": "120270399", "n_citations": 5, "n_key_citations": 1, "score": 0, "title": "Development of Optical System for ARGO M", "venue": "", "year": 2013 }, { "abstract": "The designed Active LDR(Laser Detection and Ranging) System contains high power Laser and its diameter is approximately 24mm. Although the laser transmitting channel and receiving optic channel are completely separated from each other and doesn't share any of the optical components in design, each channel shares 4 wedge scanners, which are to overcome the narrow FOV(Field of View) of the optical system. Any backward reflection back to the fiber laser end must be carefully studied since it can damage the LD(Laser Diodes) the inner components of the laser unit because of the high amplification factor of the laser unit. In this study, the stray light caused by the transmitting channel's laser and inner reflection by optical components were analyzed by ASAP(Advanced System Analysis Program) software. We also can confirm the operability and stability of the system by more than 6 months of operation of the system.", "author_names": [ "Jinsuk Hong", "Hae Seog Koh" ], "corpus_id": 119467971, "doc_id": "119467971", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Backward reflection analysis of transmitting channel of active laser ranging optics", "venue": "Optics Photonics Optical Engineering Applications", "year": 2013 } ]

[ { "abstract": "Abstract The junction temperature of the insulated gate bipolar transistor (IGBT) module, which belongs to power semiconductor devices, directly impacts on the system performance of the power conversion system (PCS) and therefore, the accurate prediction of the airflow rate passing the heat sink block of the IGBT module is very important at the thermal design stage. In this paper, the thermo fluid simulation was developed with the T Q characteristic curve to predict the junction temperature of the IGBT module and the airflow rate of the heat sink block. The porous media model was adopted in the heat sink block with fins and the filled air between fins of the heat sink block in the PCS to remove the heavily concentrated mesh problems in the heat sink block. The proposed simulation model was compared to the experimental value for the hot spot temperature on the heat sink block and the differences were within the average 4.0% margin of error in the comparison. This simulation model can be used to evaluate the suitability of the cooling design according to various operating conditions of the fan and IGBT module with benefits of the reduction in the mesh generation and the computation time. Also, this simulation model increases the flexibility of predicting the airflow rates in the PCS due to the change of the airflow passage structure in the PCS or the capacity of the fan.", "author_names": [ "Chang-Woo Han", "Seung-Boong Jeong", "Myung-Do Oh" ], "corpus_id": 3453439, "doc_id": "3453439", "n_citations": 4, "n_key_citations": 0, "score": 1, "title": "Thermo fluid simulation for the thermal design of the IGBT module in the power conversion system", "venue": "Microelectron. Reliab.", "year": 2016 }, { "abstract": "As an increasing attention towards sustainable development of energy and environment, the power electronics (PEs) are gaining more and more attraction on various energy systems. The insulated gate bipolar transistor (IGBT) as one of the PEs with numerous advantages and potentials for development of higher voltage and current ratings, has been used in a board range of applications. However, the continuing miniaturization and rapid increasing power ratings of IGBTs have remarkable high heat flux, which requires complex thermal management. In this paper, studies of the thermal management on IGBTs are generally reviewed including analyzing, comparing, and classifying the results originating from these researches. The thermal models to accurately calculate the dynamic heat dissipation are divided into analytical models, numerical models, and thermal network models, respectively. The thermal resistances of current IGBT modules are also studied. According to the current products on a number of IGBTs, we observe that the junction to case thermal resistance generally decreases inversely in terms of the total thermal power. In addition, the cooling solutions of IGBTs are reviewed and the performance of the various solutions are studied and compared. At last, we have proposed a quick and efficient evaluation judgment for the thermal management of the IGBTs depended on the requirements on the junction to case thermal resistance and equivalent heat transfer coefficient of the test samples.", "author_names": [ "Cheng Qian", "Amir Mirza Gheitaghy", "Jiajie Fan", "Hongyu Tang", "Bo Sun", "Huaiyu Ye", "Guoqi Zhang" ], "corpus_id": 4121814, "doc_id": "4121814", "n_citations": 75, "n_key_citations": 1, "score": 0, "title": "Thermal Management on IGBT Power Electronic Devices and Modules", "venue": "IEEE Access", "year": 2018 }, { "abstract": "The wind power industry has expanded greatly during the past few years, has served a growing market, and has spawned the development of larger wind turbines. Different designs and technical advances now make it possible to erect wind turbines offshore. The fast expansion of the wind power market faces some problems. The new designs are not always fully tested, and the designed 20 year lifetime is typically never achieved before the next generation of turbines are erected. This paper presents results from an investigation of failure statistics from four sources, i.e. two separate sources from Sweden, one from Finland, and one from Germany. Statistics reveal reliability performance of the different components within the wind turbine. The gearbox is the most critical, because downtime per failure is high compared to the other components. The statistical data for larger turbines also show trends toward higher, ever increasing failure frequency when compared to small turbines, which have a decreasing failure rate over the operational years", "author_names": [ "Johan Ribrant", "Lina Bertling" ], "corpus_id": 62806719, "doc_id": "62806719", "n_citations": 255, "n_key_citations": 4, "score": 0, "title": "Survey of Failures in Wind Power Systems With Focus on Swedish Wind Power Plants During 1997 2005", "venue": "IEEE Transactions on Energy Conversion", "year": 2007 }, { "abstract": "The temperature dependence and stability of three different commercially available unpackaged SiC Dmosfets have been measured. On state resistances increased to 6 or 7 times their room temperature values at 350 degC. Threshold voltages almost doubled after tens of minutes of positive gate voltage stressing at 300 degC, but approached their original values again after only one or two minutes of negative gate bias stressing. Fortunately, the change in drain current due to these threshold instabilities was almost negligible. However, the threshold approaches zero volts at high temperatures after a high temperature negative gate bias stress. The zero gate bias leakage is low until the threshold voltage reduces to approximately 150 mV, where after the leakage increases exponentially. Thermal aging tests demonstrated a sudden change from linear to nonlinear output characteristics after 24 100 h air storage at 300 degC and after 570 1000 h in N2 atmosphere. We attribute this to nickel oxide growth on the drain contact metallization which forms a heterojunction p n diode with the SiC substrate. It was determined that these state of the art SiC mosfet devices may be operated in real applications at temperatures far exceeding their rated operating temperatures.", "author_names": [ "Dean Hamilton", "M R Jennings", "Amador Perez-Tomas", "Stephen A O Russell", "Steven A Hindmarsh", "Craig A J Fisher", "Philip A Mawby" ], "corpus_id": 25386180, "doc_id": "25386180", "n_citations": 17, "n_key_citations": 1, "score": 0, "title": "High Temperature Electrical and Thermal Aging Performance and Application Considerations for SiC Power DMOSFETs", "venue": "IEEE Transactions on Power Electronics", "year": 2017 }, { "abstract": "Modular multilevel converters (MMC) are complex systems, composed of many elements, and exposed to critical load demands in some cases. Thereby, a detailed design of its components is of preeminent importance to achieve a high system level reliability. However, the high number of devices challenges the tradeoff between cost and reliability. This article, introduces a reliability oriented design methodology, based on the cost to achieve a predefined unreliability level <inline formula><tex math notation=\"LaTeX\"$U_x$/tex math>/inline formula> A flowchart presents the main steps of the process, including the mission profile definition, selection of power devices, thermal modeling, reliability modeling, and the reliability oriented selection. To evaluate the proposed methodology, a case study considering 17 MVA/13.8 kV MMC static synchronous compensator (STATCOM) with a real mission profile data is conducted. A <inline formula><tex math notation=\"LaTeX\"$U_x cost$/tex math>/inline formula> map is introduced to compare various design solutions, based on power devices of different voltage classes and current capabilities.", "author_names": [ "Joao Victor Matos Farias", "Allan Fagner Cupertino", "Victor de Nazareth Ferreira", "Heverton Augusto Pereira", "Seleme Isaac Seleme", "Remus Teodorescu" ], "corpus_id": 203073608, "doc_id": "203073608", "n_citations": 8, "n_key_citations": 1, "score": 0, "title": "Reliability Oriented Design of Modular Multilevel Converters for Medium Voltage STATCOM", "venue": "IEEE Transactions on Industrial Electronics", "year": 2020 }, { "abstract": "The need for multidisciplinary virtual prototyping in power electronics has been well established, however, design tools capable of facilitating a rapid iterative virtual design process do not exist. A key challenge in developing such tools is identifying and developing modeling techniques which can account for 3 D geometrical design choices without unduly affecting simulation speed. This challenge has been addressed in this paper using model order reduction techniques and a prototype power electronic design tool incorporating these techniques is presented. A relevant electrothermal power module design example is then used to demonstrate the performance of the software and model order reduction techniques. Five design iterations can be evaluated, using 3 D inductive and thermal models, under typical operating and start up conditions on a desktop PC in less than 15 min. The results are validated experimentally for both thermal and electrical domains.", "author_names": [ "Paul L Evans", "Alberto Castellazzi", "C Mark Johnson" ], "corpus_id": 22173158, "doc_id": "22173158", "n_citations": 25, "n_key_citations": 2, "score": 0, "title": "Design Tools for Rapid Multidomain Virtual Prototyping of Power Electronic Systems", "venue": "IEEE Transactions on Power Electronics", "year": 2016 }, { "abstract": "Over the last few decades, the production of Liquefied Natural Gas (LNG) has been pushing the development of electric drives with increasingly high power ratings, up to several tens of megawatts. A consolidated technology in this field entails dual star 2 pole synchronous motors fed by Load Commutated Inverters (LCI) with supply frequencies between 50 and 80 Hz. This paper presents a novel drive concept for very high power and high performance LNG applications based on a 45 MW 4 pole 100 Hz quadruple star synchronous motor supplied by four PWM multi level Voltage Source Inverters (VSI) The genesis, development and industrial implementation of this new design concept are outlined. System full load drive testing results are presented to successfully validate the proposed solution.", "author_names": [ "Alberto Tessarolo", "G Zocco", "C Tonello" ], "corpus_id": 8980649, "doc_id": "8980649", "n_citations": 66, "n_key_citations": 5, "score": 0, "title": "Design and testing of a 45 MW 100 Hz quadruple star synchronous motor for a Liquefied Natural Gas turbo compressor drive", "venue": "SPEEDAM 2010", "year": 2010 }, { "abstract": "In recent years, global warming and environmental pollution caused a limitation of the use of natural energy and resource use has become more important Renewable resources. In the industrial sector, most of factories such as Ceramic tile production, glass, and cement of devices that are used for heat production of biofuel. After heat generation, thermal energy balance of heat production is wasted. Thermoelectric modules with exposure to ambient air temperature difference between the devices and electrical energy will generate. Ultra long life, lack of moving parts, quiet and relatively low price thermoelectric modules, they are a very attractive option for use in the field. Since the temperature above the ambient heat is transferred from wasted heat energy transferred to the surrounding environment can be used to produce electrical energy. In this study, a review of the development of Thermoelectric cooling briefly introduced first. Next, the Ceramic Tile Production Process has been summarized. To improve performance, have been described thermoelectric cooler modeling and numerical compact model. Finally, simulation results are presented. The electrical energy generated can be transmitted to electrical energy to the distribution network that the production process is simulated by MATLAB software.", "author_names": [ "Ail Madani Mohammadi" ], "corpus_id": 55303118, "doc_id": "55303118", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Renewable Energy from Thermal: Electrical Power Generation in Ceramic and TileIndustry", "venue": "", "year": 2018 }, { "abstract": "To accelerate wide industry adoption of Silicon Carbide (SiC) based technology, a three phase two level inverter based power block is designed with the latest generation high performance 1.7 kV/450 A SiC mosfet module from General Electric. The designed power block is expected to replace the currently standardized 1.7 kV/450 A Silicon (Si) insulated gate bipolar transistor (IGBT) based three phase power block. Power converters face thermal challenges when subjected to very low fundamental frequency operations (below 10 Hz) This is particularly relevant in the wind power applications. At low operating fundamental frequencies, the junction temperature of the power device experiences high peak to peak ripple, which degrades the reliability of the power modules significantly. This paper presents the thermal performance of the designed power block and draws comparisons with a similar rated Si IGBT module based power blocks, especially at low output fundamental frequency operations. Key performance indices, including power rating curves at different switching frequencies and power factors; temperature ripple at different fundamental frequencies, are examined. Simulation and experimental results are provided to validate the claims. The results indicate that the SiC mosfet module based power block can be a promising replacement for the Si IGBT based power block especially in applications where wide range of fundamental frequency operations are needed.", "author_names": [ "Sayan Acharya", "Xu She", "Maja Harfman Todorovic", "Rajib Datta", "Gary D Mandrusiak" ], "corpus_id": 77384855, "doc_id": "77384855", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Thermal Performance Evaluation of a 1.7 kV, 450 A SiC MOSFET Based Modular Three Phase Power Block With Wide Fundamental Frequency Operations", "venue": "IEEE Transactions on Industry Applications", "year": 2019 }, { "abstract": "Thermal management is becoming ever more important in passenger vehicles in the trend of vehicle electrification. Even though most of the passenger vehicles still have relatively conventional thermal management systems, advanced technologies have been increasingly developed. The internal combustion engine have had the central role in thermal management but due to the powertrain hybridization and electrification, the engines are nowadays more efficient, smaller in size, and running less frequently. Especially for plug in hybrid and electric vehicles, engines are not always used or not even available, and, thus, there is no excess heat readily available. This paper reviews the present technology for the thermal management of electrified powertrains in passenger vehicles. In this context, thermal management takes into account the cooling and heating systems for the powertrain components, and different methods to develop and improve thermal systems efficiency. This paper investigates the recent technology advances for improving energy efficiency of thermal systems. The research focus is on the hybrid and electric vehicles and especially on the challenges of improving thermal energy efficiency and performance.", "author_names": [ "Antti Lajunen", "Yinye Yang", "Ali Emadi" ], "corpus_id": 56594799, "doc_id": "56594799", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Recent Developments in Thermal Management of Electrified Powertrains", "venue": "IEEE Transactions on Vehicular Technology", "year": 2018 } ]

[ { "abstract": "Localized surface plasmon resonances (LSPRs) enable tailoring of the optical response of nanomaterials through their free carrier concentration, morphology, and dielectric environment. Recent efforts to expand the spectral range of usable LSPR frequencies into the infrared successfully demonstrated LSPRs in doped semiconductor nanocrystals. Despite silicon's importance for electronic and photonic applications, no LSPRs have been reported for doped silicon nanocrystals. Here we demonstrate doped silicon nanocrystals synthesized via a nonthermal plasma technique that exhibits tunable LSPRs in the energy range of 0.07 0.3 eV or mid infrared wavenumbers of 600 2500 cm( 1)", "author_names": [ "David J Rowe", "Jong Seok Jeong", "K Andre Mkhoyan", "Uwe R Kortshagen" ], "corpus_id": 17249429, "doc_id": "17249429", "n_citations": 140, "n_key_citations": 3, "score": 1, "title": "Phosphorus doped silicon nanocrystals exhibiting mid infrared localized surface plasmon resonance.", "venue": "Nano letters", "year": 2013 }, { "abstract": "Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 August 8, 2013.", "author_names": [ "Jong Seok Jeong", "David J Rowe", "Uwe R Kortshagen", "K Andre Mkhoyan" ], "corpus_id": 138873019, "doc_id": "138873019", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Analytical STEM Study of P Doped Silicon Nanocrystals Exhibiting Mid Infrared Localized Surface Plasmon Resonance", "venue": "Microscopy and Microanalysis", "year": 2013 }, { "abstract": "Localized surface plasmon resonance (LSPR) of doped Si nanocrystals (NCs) is critical to the development of Si based plasmonics. We now experimentally show that LSPR can be obtained from both B and P doped Si NCs in the mid infrared region. Both experiments and calculations demonstrate that the Drude model can be used to describe the LSPR of Si NCs if the dielectric screening and carrier effective mass of Si NCs are considered. When the doping levels of B and P are similar, the LSPR energy of B doped Si NCs is higher than that of P doped Si NCs because B is more efficiently activated to produce free carriers than P in Si NCs. We find that the plasmonic coupling between Si NCs is effectively blocked by oxide at the NC surface. The LSPR quality factors of B and P doped Si NCs approach those of traditional noble metal NCs. We demonstrate that LSPR is an effective means to gain physical insights on the electronic properties of doped Si NCs. The current work on the model semiconductor NCs, i.e. Si NCs has important implication for the physical understanding and practical use of semiconductor NC plasmonics.", "author_names": [ "Shu Hong Zhou", "Xiaodong Pi", "Zhenyi Ni", "Yi Ding", "Yingying Jiang", "Chuanhong Jin", "Christophe Delerue", "Deren Yang", "Tomohiro Nozaki" ], "corpus_id": 5354249, "doc_id": "5354249", "n_citations": 93, "n_key_citations": 1, "score": 0, "title": "Comparative study on the localized surface plasmon resonance of boron and phosphorus doped silicon nanocrystals.", "venue": "ACS nano", "year": 2015 }, { "abstract": "Colloidal nanocrystals of anatase TiO2 exhibit localized surface plasmon resonance (LSPR) in the mid infrared upon carrier accumulation through synthetic doping or electrochemical reduction. However, the energy and intensity of LSPR in anatase TiO2 nanocrystals is anomalously low compared to those of other transparent conductive oxides with similar bulk conductivity. Here, the electronic origin of LSPR energy and intensity in TiO2 nanocrystals is quantified by measuring infrared transmittance of dilute dispersions of doped nanocrystals and ex situ charged thin films. Optical modeling of infrared spectra reveals that TiO2 nanocrystals can accommodate carrier concentrations exceeding 1.5 x 1021 cm 3 upon charging, but the large effective mass along the anatase c axis is found to diminish the infrared absorption of TiO2 nanocrystals. The respective effects of crystalline anisotropy, synthetic doping, and electrochromic charging on LSPR in TiO2 nanocrystals are investigated, revealing promising new avenues to.", "author_names": [ "Clayton J Dahlman", "Ankit Agrawal", "Corey M Staller", "Jacob Adair", "Delia J Milliron" ], "corpus_id": 104452208, "doc_id": "104452208", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Anisotropic Origins of Localized Surface Plasmon Resonance in n Type Anatase TiO2 Nanocrystals", "venue": "", "year": 2019 }, { "abstract": "A central theme of nanocrystal (NC) research involves the synthesis of dimension controlled NCs and studies of size dependent scaling laws governing their optical, electrical, magnetic, and thermodynamic properties. Here we describe the synthesis of monodisperse CdO NCs that exhibit high quality factor (up to 5.5) mid infrared (MIR) localized surface plasmon resonances (LSPR) and elucidate the inverse scaling relationship between carrier concentration and NC size. The LSPR wavelength is readily tunable between 2.4 and ~6.0 mm by controlling the size of CdO NCs. Structural and spectroscopic characterization provide strong evidence that free electrons primarily originate from self doping due to NC surface induced nonstoichiometry. The ability to probe and to control NC stoichiometry and intrinsic defects will pave the way toward predictive synthesis of doped NCs with desirable LSPR characteristics.", "author_names": [ "Zeke Liu", "Yaxu Zhong", "Ibrahim Shafei", "Soojin Jeong", "Liguang Wang", "Hoai Thuong Nguyen", "Cheng Sun", "Tao Li", "Jianyun Chen", "Liquan Chen", "Yaroslav Losovyj", "Xinfeng Gao", "Wanli Ma", "Xingchen Ye" ], "corpus_id": 211557290, "doc_id": "211557290", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Broadband Tunable Mid infrared Plasmon Resonances in Cadmium Oxide Nanocrystals Induced by Size dependent Nonstoichiometry.", "venue": "Nano letters", "year": 2020 }, { "abstract": "We observe and systematically tune an intense mid infrared absorption mode that results from phosphorus doping in silicon nanowires synthesized via the vapor liquid solid technique. The angle and shape dependence of this spectral feature, as determined via in situ transmission infrared spectroscopy, supports its assignment as a longitudinal localized surface plasmon resonance (LSPR) Modulation of resonant frequency (740 1620 cm( 1) is accomplished by varying nanowire length (135 1160 nm) The observed frequency shift is consistent with Mie Gans theory, which indicates electrically active dopant concentrations between 10(19) and 10(20) cm( 3) Our findings suggest new opportunities to confine light in this ubiquitous semiconductor and engineer the optical properties of nontraditional plasmonic materials.", "author_names": [ "Li-wei Chou", "Naechul Shin", "Saujan V Sivaram", "Michael A Filler" ], "corpus_id": 207088062, "doc_id": "207088062", "n_citations": 71, "n_key_citations": 2, "score": 0, "title": "Tunable mid infrared localized surface plasmon resonances in silicon nanowires.", "venue": "Journal of the American Chemical Society", "year": 2012 }, { "abstract": "Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron doped silicon nanocrystals excited with mid IR optical pulses. Unlike previous silicon based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p type silicon nanocrystals. The choice of optical excitation wavelength allows for selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid IR optical pumping heats the free holes of p Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective mass at high effective hole temperatures lead to a subpicosecond change of the dielectric function, resulting in a redshift of the LSPR, modulating mid IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid IR. Low hole heat capacity dictates subpicosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein Moss effect, permitting the modulation of transmittance at telecommunications wavelengths. The results presented here show that doped silicon, particularly in micro or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.", "author_names": [ "Benjamin T Diroll", "Katelyn S Schramke", "Peijun Guo", "Uwe R Kortshagen", "Richard D Schaller" ], "corpus_id": 40293128, "doc_id": "40293128", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Ultrafast Silicon Photonics with Visible to Mid Infrared Pumping of Silicon Nanocrystals.", "venue": "Nano letters", "year": 2017 }, { "abstract": "Degenerately doped semiconductor nanocrystals (NCs) exhibit strong light matter interactions due to localized surface plasmon resonance (LSPR) in the near to mid infrared region. Besides being readily tuned through dopant concentration introduced during synthesis, this LSPR can also be dynamically modulated by applying an external electrochemical potential. This characteristic makes these materials candidates for electrochromic window applications. Here, using prototypical doped indium oxide NCs as a model system, we find that the extent of electrochemical modulation of LSPR frequency is governed by the depletion width and the extent of inter NC LSPR coupling, which are indirectly controlled by the dopant density, size, and packing density of the NCs. The depletion layer is a near surface region with a sharply reduced free carrier population that occurs whenever the surface potential lies below the Fermi level. Changes in the depletion width under applied bias substantially control the spectral modulation of the LSPR of individual NCs and also modify the inter NC LSPR coupling, which additionally modulates the LSPR absorption on the NC film scale. Here, we show that both of these effects must be considered primary factors in determining the extent of LSPR frequency modulation and that the dominant factor depends on NC size. For a constant doping concentration, depletion effects govern LSPR modulation for smaller NCs, while LSPR coupling is prevalent in larger NCs. Consequently, as the size of the NCs is increased while keeping the doping concentration constant, we observe a reversal in the sign of the LSPR frequency modulation from positive to negative.", "author_names": [ "Bharat Tandon", "Ankit Agrawal", "Sung Yeon Heo", "Delia J Milliron" ], "corpus_id": 73484223, "doc_id": "73484223", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "Competition between Depletion Effects and Coupling in the Plasmon Modulation of Doped Metal Oxide Nanocrystals.", "venue": "Nano letters", "year": 2019 }, { "abstract": "Metal oxides, when electronically doped with oxygen vacancies, aliovalent dopants, or interstitial dopants, can exhibit metallic behavior due to the stabilization of a substantial charge carrier concentration within the material. As a result, localized surface plasmon resonances (LSPRs) occur in nanocrystals of conducting metal oxides. Through deliberate choice of both the host material and the defect, these resonances can be tuned across the entirety of the near and mid infrared regions of the electromagnetic spectrum. Optical modeling has revealed that the defects present have profound impacts on charge carrier mobility and electronic structure, and in some cases, choosing one dopant over another is an important trade off for optimizing plasmonic performance. These materials are distinct from classical metals in that one can tune their LSPR in energy and intensity through their elemental composition independently of any particular size or nanocrystal morphology. In addition, the LSPR in these materials.", "author_names": [ "Ankit Agrawal", "Robert W Johns", "Delia J Milliron" ], "corpus_id": 138567287, "doc_id": "138567287", "n_citations": 81, "n_key_citations": 1, "score": 0, "title": "Control of Localized Surface Plasmon Resonances in Metal Oxide Nanocrystals", "venue": "", "year": 2017 }, { "abstract": "Degenerately doped silicon nanocrystals are appealing plasmonic materials due to silicon's low cost and low toxicity. While surface plasmonic resonances of boron doped and phosphorus doped silicon nanocrystals were recently observed, there currently is poor understanding of the effect of surface conditions on their plasmonic behavior. Here, we demonstrate that phosphorus doped silicon nanocrystals exhibit a plasmon resonance immediately after their synthesis but may lose their plasmonic response with oxidation. In contrast, boron doped nanocrystals initially do not exhibit plasmonic response but become plasmonically active through postsynthesis oxidation or annealing. We interpret these results in terms of substitutional doping being the dominant doping mechanism for phosphorus doped silicon nanocrystals, with oxidation induced defects trapping free electrons. The behavior of boron doped silicon nanocrystals is more consistent with a strong contribution of surface doping. Importantly, boron doped silicon nanocrystals exhibit air stable plasmonic behavior over periods of more than a year.", "author_names": [ "Nicolaas J Kramer", "Katelyn S Schramke", "Uwe R Kortshagen" ], "corpus_id": 12010503, "doc_id": "12010503", "n_citations": 93, "n_key_citations": 1, "score": 0, "title": "Plasmonic Properties of Silicon Nanocrystals Doped with Boron and Phosphorus.", "venue": "Nano letters", "year": 2015 } ]

[ { "abstract": "Semiconductor fundamentals carrier scattering Monte Carlo transport calculation Monte Carlo device simulation balance equation method for device simulation.", "author_names": [ "Fu Ze Yi Long" ], "corpus_id": 106724249, "doc_id": "106724249", "n_citations": 61, "n_key_citations": 3, "score": 2, "title": "Numerical simulation of submicron semiconductor devices", "venue": "", "year": 1993 }, { "abstract": "The hydrodynamic model treats electron flow in a semiconductor device through the Euler equations of gas dynamics, with the addition of a heat conduction term. Thus the hydrodynamic model PDEs have hyperbolic, parabolic, and elliptic modes. The nonlinear hyperbolic modes support shock waves. Numerical simulations of a steady state electron shock wave in a submicron semiconductor device are presented, using a steady state second upwind upwind method. For the n n n diode (which models the channel of a MOSFET) the shock wave is fully developed in Si (with a 1 volt bias) at 300 K for a 0.1 micron channel and at 77 K for a 1.0 micron channel.", "author_names": [ "Carl L Gardner" ], "corpus_id": 52831447, "doc_id": "52831447", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Upwind Simulation of a Steady State Electron Shock Wave in a Submicron Semiconductor Device", "venue": "", "year": 2014 }, { "abstract": "In this paper, we apply our proposed early parallel adaptive computing methodology for numerical solution of semiconductor device equations with triangular meshing technique. This novel simulation based on adaptive triangular mesh, finite volume, monotone iterative, and a posteriori error estimation methods, is developed and successfully implemented on a Linux cluster with message passing interface (MPI) library. Parallel adaptive computing with triangular mesh has its flexibility to simulate multidimensional semiconductor devices with highly complicated geometry. Our approach fully exploits the inherent parallelism of the triangular mesh finite volume as well as monotone iterative methods for semiconductor drift diffusion equations on a Linux cluster parallel computing system. Parallel simulation results demonstrate an excellent speedup with respect to the number of processors. Benchmarks and numerical results for a submicron N MOSFET device are also presented to show the robustness and efficiency of the method. Key Words: Monotone Iterative Method, Finite Volume Method, Adaptive Refinement, Triangular Mesh, Cluster Computing, Drift Diffusion Equations, MOSFET", "author_names": [ "Yiming Li", "Cheng-Kai Chen", "Pu Chen" ], "corpus_id": 14662615, "doc_id": "14662615", "n_citations": 5, "n_key_citations": 3, "score": 0, "title": "Monotone iterative method and adaptive finite volume method for parallel numerical simulation of submicron MOSFET devices", "venue": "", "year": 2001 }, { "abstract": "Bearing in mind the requirements of design engineers, a nonlinear model is developed to simulate the temperature dependent I V characteristics of submicron high electron mobility transistors (HEMTs) Self and ambient heating effects are incorporated into the model expression to cater for both the negative and positive conductance of the device, after the onset of the saturation current. It is shown that the accuracy of numerical models previously developed for metal semiconductor field effect transistors (MESFETs) deteriorates when simulating the I V characteristics of gallium nitride (GaN) HEMTs, primarily due to the self heating effects. The validity of the proposed model is checked for GaN HEMTs with gate length $L_\\mathrm{g}$Lg) ranging from 0.12 to 0.7 \\upmu \\hbox {m}$mm in the temperature range of $T=298$$T=298 to $T=773$$T=773 K. It is demonstrated that the proposed model simulates, with a good degree of accuracy, the output characteristics of such devices exhibiting negative conductance in the saturation region of operation. It is observed that, for devices exhibiting negative conductance in the saturation region, the peak transconductance $g_\\mathrm{m}$gm) occurs at a relatively higher negative gate bias while the peak value reduces with increasing ambient temperature. The root mean square errors reveal that the proposed model is better than other similar models reported in the literature, with an improvement varying from 17 to 50 depending on the device characteristics.", "author_names": [ "M N Khan", "Umer Farooq Ahmed", "M Mansoor Ahmed", "Saif-Ur Rehman" ], "corpus_id": 125313887, "doc_id": "125313887", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Simulation and comparative analysis of the DC characteristics of submicron GaN HEMTs for use in CAD software", "venue": "", "year": 2019 }, { "abstract": "Abstract A new set of semiconductor equations is proposed here which will be suitable for the numerical study of the carrier transport effects in submicron devices. With simplified models and comprehensive numerical techniques, the relative importance (on the device behavior) of several physical effects, such as velocity overshoot, intracollisional field effect, avalanche breakdown, carrier generation and temperature effect can be determined. The program that is capable of solving this set of equations will become an indispensible CAD tool if the current trend of the decreasing of the device dimensions continues.", "author_names": [ "Cheng T Wang" ], "corpus_id": 97485224, "doc_id": "97485224", "n_citations": 29, "n_key_citations": 2, "score": 0, "title": "A new set of semiconductor equations for computer simulation of submicron devices", "venue": "", "year": 1985 }, { "abstract": "A new approach, called monotone iterative (MI) method, for the numerical solution of semiconductor device equations is presented. This constructive method is intended to alleviate some major difficulties particularly associated with Newton's method that is the principal methodology to date for the solution of nonlinear semiconductor device equations. The method converges globally with arbitrary initial guess under various bias conditions for a submicron MOSFET. By comparing with a Newton's iterative (NI) method, a speed up factor of 30 in CPU time can be achieved by the MI method. The method is highly parallel and easy to implement for two and three dimensional simulations. Numerical simulations on a submicron N MOSFET device with various biasing conditions and initial guesses are presented to demonstrate the efficiency of the method.", "author_names": [ "Yiming Li", "S Chung", "Jinn-Liang Liu" ], "corpus_id": 60498731, "doc_id": "60498731", "n_citations": 15, "n_key_citations": 5, "score": 0, "title": "A novel approach for the two dimensional simulation of submicron MOSFETs using monotone iterative method", "venue": "1999 International Symposium on VLSI Technology, Systems, and Applications. Proceedings of Technical Papers. (Cat. No.99TH8453)", "year": 1999 }, { "abstract": "In this paper, we apply our proposed computing algorithm for numerical solution of semiconductor device energy balance equation in carrier temperature simulation. This robust simulation based on finite volume discertization scheme and monotone iterative algorithm is successfully developed and implemented for intrinsic investigation of submicron MOSFET device. Simulation results demonstrate MOSFET electron temperature can be significantly controlled with lightly doped drain (LDD) structure. Global convergence behavior is also presented to show the robustness and efficiency of the method. Key Words: Carrier Temperature Calculation, Monotone Iterative Algorithm, LDD, MOSFET", "author_names": [ "Yiming LI National" ], "corpus_id": 18719461, "doc_id": "18719461", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "A Novel Approach to Carrier Temperature Calculation for Semiconductor Device Simulation using Monotone Iterative Method Part II Numerical Results", "venue": "", "year": 2001 }, { "abstract": "In this paper, we solve numerically a semiconductor device energy balance equation using monotone iterative method. With the proposed solution technique, we prove the solution of nite volume discretized semiconductor device energy balance equation converges monotonically. The method presented here provides an e+ cient approach for the numerical solution of energy balance equation in submicron semiconductor device simulation.", "author_names": [ "Li Yiming" ], "corpus_id": 9336528, "doc_id": "9336528", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "A Novel Approach to Carrier Temperature Calculation for Semiconductor Device Simulation using Monotone Iterative Method Part I Numerical Algorithm", "venue": "", "year": 2001 }, { "abstract": "An efficient numerical solution scheme based on a new generalized finite difference discretization and iterative strategies is developed for submicron semiconductor devices. As a representative model we consider a non parabolic hydrodynamic system. The discretization is formulated in a mapped reference domain, and incorporates a transformed Scharfetter Gummel treatment for the current density and energy flux. This permits the use of graded, nonuniform curvilinear grids in the physical domain of interest, which has advantages when gridding irregular domain shapes or solution profiles. The solution of the discrete system is carried out in a fully coupled, implicit form, and non symmetric gradient type iterative strategies are investigated. Numerical results demonstrating the performance and reliability of the scheme are presented for ID and 2D test problems.", "author_names": [ "Anand L Pardhanani", "Graham F Carey" ], "corpus_id": 2720208, "doc_id": "2720208", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Simulation of Hydrodynamic Semiconductor Device Models Using a Modified Scharfetter Gummel Strategy", "venue": "", "year": 2006 }, { "abstract": "An efficient numerical solution scheme based on a new mapped finite difference discretization and iterative strategies is developed for submicron semiconductor devices. As a representative model we consider a nonparabolic hydrodynamic system. The discretization is formulated in a mapped reference domain, and incorporates a transformed Scharfetter Gummel treatment for the current density and energy flux. This permits the use of graded, nonuniform curvilinear grids in the physical domain of interest, which has advantages when gridding irregular domain shapes or grading meshes for steep solution profiles. The solution of the discrete system is carried out in a fully coupled, implicit form, and nonsymmetric gradient type iterative strategies are investigated. Numerical results demonstrating the performance and reliability of the scheme are presented for test problems.", "author_names": [ "Anand L Pardhanani", "Graham F Carey" ], "corpus_id": 37659659, "doc_id": "37659659", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "A mapped Scharfetter Gummel formulation for the efficient simulation of semiconductor device models", "venue": "IEEE Trans. Comput. Aided Des. Integr. Circuits Syst.", "year": 1997 } ]

[ { "abstract": "The explosive growth in the semiconductor industry has caused a rapid evolution of thin film materials that lend themselves to the fabrication of state of the art semiconductor devices. Early in the 1960s an old research technique named chemical vapour phase deposition (CVD) which has several unique advantages, developed into the most widely used technique for thin film preparation in electronics technology. In the last 25 years, tremendous advances have been made in the science and technology of thin films prepared by means of CVD. This book presents in a single volume, an up to date overview of the important field of CVD processes which has never been completely reviewed previously. Contents: Part I. 1. Evolution of CVD Films. Introductory remarks. Short history of CVD thin films. II. Fundamentals. 2. Techniques of Preparing Thin Films. Electrolytic deposition techniques. Vacuum deposition techniques. Plasma deposition techniques. Liquid phase deposition techniques. Solid phase deposition techniques. Chemical vapour conversion of substrate. Chemical vapour deposition. Comparison between CVD and other thin film deposition techniques. 3. Chemical Processes Used in CVD.", "author_names": [ "Constantin Morosanu" ], "corpus_id": 136885303, "doc_id": "136885303", "n_citations": 89, "n_key_citations": 8, "score": 1, "title": "Thin films by chemical vapour deposition", "venue": "", "year": 1990 }, { "abstract": "Air stable caesium tin iodide double perovskite (Cs2SnI6) thin films have been fabricated via aerosol assisted chemical vapour deposition (AACVD) We compare the properties of the double perovskite films made using AACVD with those made by the widely used spin coating method. Films with purer crystalline phase (less CsI impurity) and far better stability in ambient air can be obtained by AACVD compared with spin coating. The AACVD grown Cs2SnI6 films retain high phase purity for at least ~100 days aging in air with negligible CsI impurities detected over this time, as determined by X ray diffraction. The films exhibit an optical band gap energy (Eg) of ca. 1.3 eV and a homogeneous morphology with the expected nominal stoichiometry within error, as probed by energy dispersive X ray spectroscopy. Overall, the characteristics of the Cs2SnI6 films are highly process dependent, e.g. they are influenced by the presence of hydroiodic acid (HI) in the precursor solution. Without HI addition, an iodine deficient film with more CsI is produced, which also exhibits a larger Eg of ca. 1.6 eV. In addition to bulk properties, we utilise X ray photoelectron spectroscopy (XPS) to scrutinise the surface characteristics in detail. We find excess Sn and I located at the surfaces. This can be attributed to the presence of SnI4 from the deposition precursor vapour. Furthermore, following aging in air, an increase in CsI impurity for the AACVD +HI) grown film is observed, along with a reduction in SnI4 at the surfaces. Near ambient pressure XPS (NAP XPS) is used to examine the surface stability of AACVD +HI) grown films on exposure to O2 and H2O. No enhancement in the amount of CsI impurity is observed after both H2O vapour (9 mbar) and O2 (5 mbar) exposure. Nevertheless, the concentrations of tin and iodine change after exposure, suggesting that SnI4 protects Cs2SnI6 from degradation. This passivation effect of SnI4 on Cs2SnI6 surfaces is proposed to explain the additional stability of Cs2SnI6 fabricated via AACVD.", "author_names": [ "Jack Chun-Ren Ke", "David J Lewis", "Alex S Walton", "Ben F Spencer", "Paul O'Brien", "Andrew G Thomas", "Wendy R Flavell" ], "corpus_id": 102615251, "doc_id": "102615251", "n_citations": 37, "n_key_citations": 1, "score": 0, "title": "Ambient air stable inorganic Cs2SnI6 double perovskite thin films via aerosol assisted chemical vapour deposition", "venue": "", "year": 2018 }, { "abstract": "Epitaxial e gallium oxide (Ga2O3) thin films incorporated with In were successfully grown by mist chemical vapour deposition (CVD) on c plane sapphire substrates for bandgap tuning. In was successfully incorporated into epitaxial e (InxGa1 x)2O3 films at an In composition of x 0.2 without inducing phase separation. Phase separation originated from the (400) bixbyite structure of (InxGa1 x)2O3 when x 0.2. The solubility limit of In incorporated into e Ga2O3 on sapphire substrates via mist CVD was therefore x 0.2. Transmission electron microscopy measurements revealed that e (InxGa1 x)2O3 consisted of polycrystalline phases observed in the interface of the sapphire substrate and e phases located above the polycrystalline phase. The pole figure of e (InxGa1 x)2O3 thin films revealed that the epitaxial relationship between the e (InxGa1 x)2O3 thin film and the a Al2O3 substrate is (001) e (InxGa1 x)2O3 [130](0001) a Al2O3 [11 20] The optical bandgap of the e (InxGa1 x)2O3 thin films was tuned from 4.5 to 5.0 eV without inducing phase separation.", "author_names": [ "Hiroyuki Nishinaka", "Nobutaka Miyauchi", "Daisuke Tahara", "Shota Morimoto", "Masahiro Yoshimoto" ], "corpus_id": 103239599, "doc_id": "103239599", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Incorporation of indium into e gallium oxide epitaxial thin films grown via mist chemical vapour deposition for bandgap engineering", "venue": "", "year": 2018 }, { "abstract": "Integrating metal organic frameworks (MOFs) in microelectronics has disruptive potential because of the unique properties of these microporous crystalline materials. Suitable film deposition methods are crucial to leverage MOFs in this field. Conventional solvent based procedures, typically adapted from powder preparation routes, are incompatible with nanofabrication because of corrosion and contamination risks. We demonstrate a chemical vapour deposition process (MOF CVD) that enables high quality films of ZIF 8, a prototypical MOF material, with a uniform and controlled thickness, even on high aspect ratio features. Furthermore, we demonstrate how MOF CVD enables previously inaccessible routes such as lift off patterning and depositing MOF films on fragile features. The compatibility of MOF CVD with existing infrastructure, both in research and production facilities, will greatly facilitate MOF integration in microelectronics. MOF CVD is the first vapour phase deposition method for any type of microporous crystalline network solid and marks a milestone in processing such materials.", "author_names": [ "Ivo Stassen", "Mark J Styles", "Gianluca Grenci", "Hans Van Gorp", "Willem Vanderlinden", "Steven De Feyter", "Paolo Falcaro", "Dirk De Vos", "Philippe M Vereecken", "Rob Ameloot" ], "corpus_id": 26153066, "doc_id": "26153066", "n_citations": 297, "n_key_citations": 1, "score": 0, "title": "Chemical vapour deposition of zeolitic imidazolate framework thin films.", "venue": "Nature materials", "year": 2016 }, { "abstract": "Methyl ammonium lead iodide is the archetypal perovskite solar cell material. Phase pure, compositionally uniform methyl ammonium lead iodide thin films on large glass substrates were deposited using ambient pressure aerosol assisted chemical vapour deposition. This opens up a route to efficient scale up of hybrid perovskite film growth towards industrial deployment.", "author_names": [ "Davinder Singh Bhachu", "David O Scanlon", "E J Saban", "Hugo Bronstein", "Ivan P Parkin", "Claire J Carmalt", "Robert G Palgrave" ], "corpus_id": 135888076, "doc_id": "135888076", "n_citations": 60, "n_key_citations": 0, "score": 0, "title": "Scalable route to CH3NH3PbI3 perovskite thin films by aerosol assisted chemical vapour deposition", "venue": "", "year": 2015 }, { "abstract": "Transparent conducting oxides have widespread application in modern society but there is a need to move away from the current 'industry champion' tin doped indium oxide (In2O3:Sn) due to high costs. Antimony doped tin(IV) oxide (ATO) is an excellent candidate but is limited by its opto electrical properties. Here, we present a novel and scalable synthetic route to ATO thin films that shows excellent electrical properties. Resistivity measurements showed that at 4 at% doping the lowest value of 4.7 x 10 4 O cm was achieved primarily due to a high charge carrier density of 1.2 x 1021 cm 3. Further doping induced an increase in resistivity due to a decrease in both the carrier density and mobility. Ab initio hybrid density functional theory (DFT) calculations show the thermodynamic basis for the tail off of performance beyond a certain doping level, and the appearance of Sb(III) within the doped thin films.", "author_names": [ "Sapna D Ponja", "Benjamin A D Williamson", "Sanjayan Sathasivam", "David O Scanlon", "Ivan P Parkin", "Claire J Carmalt" ], "corpus_id": 51919229, "doc_id": "51919229", "n_citations": 53, "n_key_citations": 0, "score": 0, "title": "Enhanced electrical properties of antimony doped tin oxide thin films deposited via aerosol assisted chemical vapour deposition", "venue": "", "year": 2018 }, { "abstract": "Abstract We present electrical and optical properties of CuCrO2 thin films deposited by chemical vapour deposition, as well as the influence of depositions' parameters on these properties. Oxygen partial pressure and precursor's concentrations have the greatest influence on optical and electrical properties of the films. Values of conductivities ranging from 10 4 to 10 S/cm were obtained using different deposition conditions. The conductivity is thermally activated with an activation energy ranging from 57 to 283 meV. Thermoelectric measurements confirm the p type conduction, and demonstrate high carrier concentration typical for a degenerate semiconductor. The as deposited films show a medium degree of crystallinity, a maximum optical transmission up to 80% in the visible range with a corresponding band gap around 3.2 eV.", "author_names": [ "Petru Lunca Popa", "Jonathan Crepelliere", "Renaud Leturcq", "Damien Lenoble" ], "corpus_id": 138298439, "doc_id": "138298439", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Electrical and optical properties of Cu Cr O thin films fabricated by chemical vapour deposition", "venue": "", "year": 2016 }, { "abstract": "This work describes the first Aerosol Assisted Chemical Vapour Deposition (AACVD) synthesis of photocatalytic titanium dioxide thin films embedded with synthetic hydroxyapatite, [Ca10(PO4)(OH)2] nanoparticles. The hydroxyapatite nanoparticles were prepared using a low temperature continuous hydrothermal flow synthesis method; analysis of the hydroxyapatite powder showed that it was phase pure and that the as prepared material was made up of nano needles. The nanoparticles were then embedded into TiO2 coatings using the AACVD technique by suspending them in a solution of the titania precursor (titanium tetra isopropoxide) Results showed that the hydroxyapatite, although present in very low concentrations in the coatings (not detectable by XRD or Raman spectroscopy) heavily affected their morphology, depending on their concentration in the precursor solution. Tests of the photocatalytic activity of the composite films showed that the inclusion of the hydroxyapatite led to an increase in methylene blue photodegradation (up to 50% higher) and that the materials were photostable. This study shows that TiO2 coatings embedded with hydroxyapatite nanoparticles have potential as highly efficient photocatalysts.", "author_names": [ "Clara Piccirillo", "C J Denis", "Robert C Pullar", "Russell Binions", "Ivan P Parkin", "Jawwad A Darr", "Paula M L Castro" ], "corpus_id": 99041074, "doc_id": "99041074", "n_citations": 25, "n_key_citations": 0, "score": 0, "title": "Aerosol assisted chemical vapour deposition of hydroxyapatite embedded titanium dioxide composite thin films", "venue": "", "year": 2017 }, { "abstract": "Diethyldithiocarbamato metal complexes of the general formula [M(S2CN(Et)2)n] (M Fe(III) Co(III) Ni(II) Cu(II) Zn(II) and n 2, 3) have been synthesized and used as precursors for the deposition of iron pyrite (FeS2) and transition metal doped iron pyrite (MxFe1 xS2) thin films on glass and indium tin oxide (ITO) coated glass substrates by aerosol assisted chemical vapour deposition (AACVD) Thermogravimetric analysis (TGA) confirmed that all the five complexes decompose into their corresponding metal sulfides. The iron complex [Fe(S2CNEt2)3] (1) deposited pure cubic pyrite (FeS2) films with granular crystallites at 350 degC, whereas at 450 degC pyrite and marcasite were deposited. MxFe1 xS2 (where M Co, Ni, Cu, or Zn) films were deposited by varying the relative concentration of complexes [Fe(S2CNEt2)3] (1) and [Co(S2CNEt2)3] (2) [Ni(S2CNEt2)2] (3) [Cu(S2CNEt2)2] (4) and [Zn(S2CNEt2)2] (5) at 350 degC. The formation of a solid solution was confirmed by powder X ray diffraction (p XRD) The surface morphology of the films was studied by scanning electron microscopy (SEM) whilst the height profiles of the films were revealed by atomic force microscopy (AFM) The elemental compositions of the films were confirmed by energy dispersive X ray (EDX) spectroscopy. To the best of our knowledge, these complexes are the first in their class to be used as single source precursors to deposit MxFe1 xS2 thin films.", "author_names": [ "Sadia Khalid", "Ejaz Ahmed", "Mohammad Azad Malik", "David J Lewis", "Shahzad Abu Bakar", "Yaqoob Khan", "Paul O'Brien" ], "corpus_id": 62812582, "doc_id": "62812582", "n_citations": 34, "n_key_citations": 0, "score": 0, "title": "Synthesis of pyrite thin films and transition metal doped pyrite thin films by aerosol assisted chemical vapour deposition+", "venue": "", "year": 2015 }, { "abstract": "This work discusses an application of titanium oxide (TiOx) thin films deposited using physical (reactive magnetron sputtering, RMS) and chemical (atomic layer deposition, ALD) vapour deposition methods as a functional coating for label free optical biosensors. The films were applied as a coating for two types of sensors based on the localised surface plasmon resonance (LSPR) of gold nanoparticles deposited on a glass plate and on a long period grating (LPG) induced in an optical fibre. Optical and structural properties of the TiOx thin films were investigated and discussed. It has been found that deposition method has a significant influence on optical properties and composition of the films, but negligible impact on TiOx surface silanization effectiveness. A higher content of oxygen with lower Ti content in the ALD films leads to the formation of layers with higher refractive index and slightly higher extinction coefficient than for the RMS TiOx. Moreover, application of the TiOx film independently on deposition method enables not only for tuning of the spectral response of the investigated biosensors, but also in case of LSPR for enhancing the ability for biofunctionalization, i.e. TiOx film mechanically protects the nanoparticles and induces change in the biofunctionalization procedure to the one typical for oxides. TiOx coated LSPR and LPG sensors with refractive index sensitivity of close to 30 and 3400nm/RIU, respectively, were investigated. The ability for molecular recognition was evaluated with the well known complex formation between avidin and biotin as a model system. The shift in resonance wavelength reached 3 and 13.2nm in case of LSPR and LPG sensors, respectively. Any modification in TiOx properties resulting from the biofunctionalization process can be also clearly detected.", "author_names": [ "Magdalena Dominik", "Adam Lesniewski", "Marta Janczuk", "Joanna Niedziolka-Jonsson", "Marcin Holdynski", "Lukasz Wachnicki", "Marek Godlewski", "Wojtek J Bock", "Mateusz Smietana" ], "corpus_id": 9999847, "doc_id": "9999847", "n_citations": 28, "n_key_citations": 1, "score": 0, "title": "Titanium oxide thin films obtained with physical and chemical vapour deposition methods for optical biosensing purposes.", "venue": "Biosensors bioelectronics", "year": 2017 } ]

[ { "abstract": "This study investigates the effects of strategic alliances on individual company performances and holistic alliance performance. It also builds on the KMV model to examine the mediating roles of trust and commitment. 121 surveys obtained from 141 firms in the Taiwan semiconductor industry. Data analyses by SEM show (1) Commitment significantly affects the performance of individual companies and the overall performance of the alliance as a whole. (2) Relationship benefits are positively related to commitment. (3) Structured bond is positively related to trust. The findings of this study provide the academia and practitioners with insights on how a strategic alliance relationship will influence individual company performance and holistic alliance performance.", "author_names": [ "Mei Hua Huang", "Chia-Hui Hsieh", "Perng-Fei Huang", "Chiung-Yen Chen" ], "corpus_id": 219605831, "doc_id": "219605831", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Examining the Impacts of Strategic Alliance Examples of the Taiwan Semiconductor Industry", "venue": "IMIS", "year": 2020 }, { "abstract": "Strategic alliance is the common use of resources and core competences by the enterprises in the production, distribution and development of goods and services in order to gain a competitive advantage in the sector. The aim of strategic alliance is to create new value by creating synergy in production, R D and marketing. By using strategic collaboration techniques, airline companies can provide advantages such as economic, financial and managerial development, expansion of flight networks and increasing market share. It is also beneficial for the airline companies to cooperate among themselves. Collaboration applications reduces the transfer and waiting times of passengers, provides more flight options, provides rewards for frequent flying passengers, provides reservation priority and standardized service. In this study, strategic collaboration techniques are explained with examples. The quantity and quality of the strategic alliance organizations Star Alliance, Skyteam and Oneworld alliances are compared according to many criteria. It was determined that the Star Alliance is advanced in terms of quantity and quality.", "author_names": [ "Sabiha ANNAC GOV" ], "corpus_id": 218970004, "doc_id": "218970004", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "STRATEGIC ALLIANCES IN AIRLINE BUSINESS: COMPARISON OF SKYTEAM, ONEWORLD, STAR ALLIANCE GROUPS", "venue": "", "year": 2020 }, { "abstract": "The aim of this paper is to show the importance of relationship marketing in business to business contexts and present a \"Model of Relationship Management Variables in B2B Environments\" First, the article gives an explanation of the paradigm shift in today's marketing understanding vis a vis the traditional transaction oriented view of marketing. Further, the article looks into business to business applications of relationship marketing, gives a definiuon of strategic alliances, which are examples of interfirm relationships and presents relationship variables affecting every single phase of an alliance. The article ends with the explanation of a \"Relationship Net\" in which the strategic alliance does not only cover two partners but a whole set of partners along the value chain.", "author_names": [ "Dilek Zamantili Nayir" ], "corpus_id": 197896747, "doc_id": "197896747", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "STRATEGIC ALLIANCES AS EXAMPLES FOR RELATIONSHIP MANAGEMENT IN B2B ENVIRONMENTS", "venue": "", "year": 2020 }, { "abstract": "Based on the basic theory of the formation of enterprise strategic alliance, we made electronic enterprises in Shenzhen as the object of the study to discuss the factors of the formation of strategic alliances from corporate social capital. The main conclusions included three points: first, the formation of strategic alliance should base on building the breadth and depth of corporate social networks, second, the history of mutual trust is the key factor of combining between enterprises, third, the role of cognitive dimension in the formation of strategic alliance is not obvious.", "author_names": [ "Cui Shi-juan", "Liu Jun", "Zhen Jian-cun" ], "corpus_id": 63037772, "doc_id": "63037772", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The Formation of Strategic Alliance's Research on the View of the Dimension of Corporate Social Capital: Take Electronic Enterprises in Shenzhen as Examples", "venue": "ICEE 2012", "year": 2012 }, { "abstract": "(p. 171) It changed its production model to one in which Iranian natives investigated and wrote the news stories as well as reported them, and it instituted journalism training programmes for its growing cadre of native reporters. In so doing, the Persian Service helped foster a generation of Iranians committed to the values associated with a vigorous and free press the backbone of British democracy. More than an institutional history, Persian Service is replete with new insights and welldocumented examples of the challenges to state sponsored media in the Middle East. It makes a valuable contribution toward filling the lacuna in the literature on mass communications in the development of the modern Iranian state.", "author_names": [ "Hossein Abadian" ], "corpus_id": 147207178, "doc_id": "147207178", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "US Foreign Policy and the Iranian Revolution: The Cold War Dynamics of Engagement and Strategic Alliance", "venue": "", "year": 2016 }, { "abstract": "Choosing proper partners is the key to the success of the alliance. Based on the analysis of the characters of the Industrial Technology Innovation Strategic Alliance, a new kind of cooperative organization occurred in China in recent years. The problem of \"adverse selection\" at the stage of the its establishment is discussed in this paper. The game model is built based on motivation theory and the principle agent theory and then proved by examples. The conclusions can be got from the model. By setting the ranges of funds, preferential policy, and sharable profits and designing membership rules, the organizer of the Industrial Technology Innovation Strategic Alliance can motivate the risk neutral applicant to reveal his real capacity and the one with higher capacity to participate intothe alliance more actively and even can set capacity threshold for applicants implicitly.", "author_names": [ "Mingxia Zhao", "Changhong Li" ], "corpus_id": 73592599, "doc_id": "73592599", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Motivation Mechanism Prevents Adverse Selection in Industrial Technology Innovation Strategic Alliance", "venue": "", "year": 2014 }, { "abstract": "Strategic alliances which are cooperative strategies in which firms combine some of their resources to create competitive advantages, are the primary form of cooperative strategies. Strategic alliances are an important source of resources, learning and thereby competitive advantage. Few firms have all of the resources needed to compete effectively in the current dynamic landscape. Thus, firms seek access to the necessary resources through alliances. Research on strategic alliance in the past few decades has suggested that strategic alliance dramatically reshaped the dynamic of competition. This study provides an important and useful perspective on strategic alliances. Approaches, examples, models and other tools are discussed to develop a deeper understanding of how competitive advantage of the alliance can be achieved.", "author_names": [ "Mowla Mohammad Masrurul" ], "corpus_id": 166335474, "doc_id": "166335474", "n_citations": 15, "n_key_citations": 3, "score": 0, "title": "An Overview of Strategic Alliance: Competitive Advantages in Alliance Constellations", "venue": "", "year": 2012 }, { "abstract": "This chapter has two primary purposes. The first is to think through the concept of cooperation and its relevance for strategic alliances. The second is to analyze the potential role of information technology in such alliances. Specifically in the latter we focus on examples of \"total\" IT outsourcing often cited as forms of \"strategic alliance\" to examine the structure of cooperation, the relationships formed, how structure and relationships evolve, and the degree to which they might be sustainable. Here, as in all our chapters, \"total\" IT outsourcing is taken to be where 80% or more of an organization's IT budget is spent on third party management of IT assets, people and/or activities to required/agreed results (Lacity and Willcocks, 1998) In the mid 1990s, when an earlier version of this chapter was published, the topic of cooperation in strategic alliances, especially in the specific area of IT outsourcing, was relatively undeveloped in the academic management studies literature. \"Undeveloped\" refers to a lack of agreement on definitions of fundamental concepts; wide differences in use of terms such as \"partnership\" \"strategic partnership\" and \"strategic alliance\" and a lack of academically researched case material to work through such problems, as opposed to an uncritical adoption of cases and vocabulary described in trade journals, the press, and business magazines. Subsequently the strategic alliance literature has developed immensely (for overviews see Child et al. 2006; Faulkner and Campbell, 2005) However, strategic alliances remain understudied in the IT literature (exceptions include DiRomualdo and Gurbaxani, 1998; Barthelemy and Geyer, 2004) We have suggested elsewhere that this is because, when it comes to outsourcing, strategic alliances exist more at the rhetorical level than in practice (Lacity and Willcocks, 2001, 2009)", "author_names": [ "Leslie P Willcocks", "Chong Ju Choi" ], "corpus_id": 208344930, "doc_id": "208344930", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Cooperative Partnerships and IT Outsourcing: From Contractual Obligation to Strategic Alliance?", "venue": "", "year": null }, { "abstract": "This paper investigated the impact of fairness concerns on the formation of the inventory transshipment strategy alliance through its impact on the ordering decisions and profits of two retailers. The paper introduced reference point dependency to describe the retailer's fairness concerns utility function, and modeled the strategic alliance system consisting of two retailers involved in transshipment. The conditions for the existence of Nash equilibrium solutions were given. The paper solved the impact of the fairness parameters on order quantities and profits by the implicit function theorem. Based on the theoretical analysis and numerical examples, this paper investigated the formation of a strategic alliance under asymmetric and symmetric fairness concerns. The results are as follows: (1) under asymmetric fairness concerns, when the transshipment price of the retailer with no fairness concerns is no more than the transshipment price of the retailer with fairness concerns, an inventory transshipment strategy alliance can be formed. Otherwise the retailer with no fairness concerns may need to pay the retailer with fairness concerns certain fees in order to form a strategic alliance; (2) under symmetric fairness concerns, two completely symmetric retailers can form strategic alliances.", "author_names": [ "Xiaohong Yu", "Sujuan Wang", "Xindong Zhang" ], "corpus_id": 145819055, "doc_id": "145819055", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The Impact of Fairness Concerns on the Formation of Retailers Alliance with Consideration of Transshipment", "venue": "", "year": 2019 }, { "abstract": "This article highlights several important dimensions of planning for exit from strategic alliances and also offers several examples of the disastrous consequences of inadequate exit planning. While many companies fall into the trap of having no exit plan, other companies take too simple a planning approach, wondering if the exit will be unconditionally easy or hard. A more effective approach involves questions such as \"When should the exit be easy and when should it be hard? And for which partner?\" The article develops a framework that stipulates contingency specific exit provisions for each partner in the alliance specifically, situations in which exit should be symmetric and easy for both partners, symmetric and hard for both partners, or asymmetric, hard for one partner and easy for the other. Furthermore, many alliances today reflect complex deals that cover several distinct developmental stages, each of which contains a distina set of contingencies. Such alliances require a dynamic application of the exit framework, wherein each stage of the alliance development entails a different set of exit provisions, and exit from one stage would signify the beginning of the next.", "author_names": [ "Ranjay Gulati", "Maxim Sytch", "Parth Mehrotra" ], "corpus_id": 2103402, "doc_id": "2103402", "n_citations": 69, "n_key_citations": 3, "score": 0, "title": "Breaking up is Never Easy: Planning for Exit in a Strategic Alliance", "venue": "", "year": 2008 } ]

[ { "abstract": "At present, environmental pollution caused by refractory organic pollutants becomes more serious. Semiconductor based photocatalysis technology, an idea and continuable technology by solar light driven, is widely employed to address this situation. Here, oxygen vacancy rich WO3 decorated monolayer Bi2WO6 nanosheet composite as an atomic scale heterojunction with high active species and ultrafast charge carrier transfer was rationally constructed. The atomic scale Vo WO3/Bi2WO6 composite displayed remarkable photoactivity comparing with pristine Vo WO3 and Bi2WO6 ultrathin nanosheet, and about 79.5% of Ciprofloxacin can be degraded within 120 min under visible light irradiation when 40 mg of photocatalyst was added into CIP solution (10 mg/L) The promoted photoactivity can be ascribed to the following points: (1) the composite possesses enormous surface pit, thereby expanding the species surface area and exposing more active site to promote antibiotic absorption; (2) the presence of abundant oxygen vacancy can facilitate the formation of more electrons, which can be consumed by adsorbed molecular oxygen to produce superoxide radical, thereby accelerating degradation organic pollutant; (3) ultrathin Vo WO3 nanosheet decorated monolayer Bi2WO6 can shorten the charge carrier transfer distance and enlarge interface contact area, then ensuring remarkable photodegradation efficiency. The reasons for promoted photodegradation efficiency were elaborated based on experiments results and ESR analysis and the degradation pathways of CIP were recorded via (LC MS)/MS] After 5 run for the degradation of CIP, Vo WO3/Bi2WO6 composite also exhibited great photodegradation efficiency, thereby demonstrating its excellent stability and reusability.", "author_names": [ "Mingming Zhang", "Cui Lai", "Bisheng Li", "Danlian Huang", "Shiyu Liu", "Lei Qin", "Huan Yi", "Yukui Fu", "Fuhang Xu", "Minfang Li", "Ling Li" ], "corpus_id": 201805350, "doc_id": "201805350", "n_citations": 39, "n_key_citations": 0, "score": 0, "title": "Ultrathin oxygen vacancy abundant WO3 decorated monolayer Bi2WO6 nanosheet: A 2D/2D heterojunction for the degradation of Ciprofloxacin under visible and NIR light irradiation.", "venue": "Journal of colloid and interface science", "year": 2019 }, { "abstract": "Abstract In this work, Bi2WO6 hollow microspheres containing oxygen vacancies (OVs BWO) was synthesized by a solvothermal template free method. Raman, EPR and XPS spectra provide sufficient evidence for the existence of OVs in the material. Its activity toward photocatalytic nitrogen fixation was evaluated. Experimental results showed that the OVs BWO with a BET surface area of 80.5 m2g 1 exhibited the ammonia yield of 106.4 mmol*gcat 1 under simulated sunlight for 2 h, which is ca. 18 times higher than that of equal area nest like Bi2WO6 without oxygen vacancies. The enhanced activity is mainly attributed to the metastable electrons within the sub band (i.e. defect energy level) induced by oxygen vacancies to p anti bonding orbitals of N2 with a manner of the non radiative transfer, leading to the activation of nitrogen molecules. The activation and hydrogeneration processes of nitrogen at active site of OVs BWO were studied by DFT calculation and the possible mechanisms were proposed. The sub band extends the light absorption region of OVs BWO to 700 nm. Transient photocurrent response showed that the sub band electron excitation accelerates the transfer of charges and hinders the electron hole recombination. It can be perfectly reused five times when air and nitrogen are used as nitrogen sources, thus the OVs BWO hollow microspheres offer a promising alternative for efficient N2 fixation under ambient conditions.", "author_names": [ "Tianyu Wang", "Caiting Feng", "Jiquan Liu", "Huaiming Hu", "Jun Hu", "Ganglin Xue" ], "corpus_id": 233882215, "doc_id": "233882215", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Bi2WO6 hollow microspheres with high specific surface area and oxygen vacancies for efficient photocatalysis N2 fixation", "venue": "", "year": 2021 }, { "abstract": "The structure of the low temperature polar (orthorhombic) phase of russellite (Bi2WO6) was examined on artificial specimens with precise single crystal X ray diffraction experiments. The final atomic arrangement thus obtained was identical to that reported by Knight [Miner. Mag. (1992) 56, 399 409] with powder neutron diffraction. The residual density attributable to a stereochemically active lone pair of electrons of bismuth was prominent at approximately the centre of a larger cap of BiO8 square antiprisms, that is on the line from the Bi sites to an adjacent WO42 slab along the b axis direction. Quite uneven Bi O distances and the formation of a vacant coordination hemisphere (within 3 A) should, therefore, be ascribed to the strong demand of bismuth to form shorter Bi O bonds to use up its electrostatic charge within its coordination environment. The shift of bismuth along c propagates via the correlated shift of the W site and these cooperative shifts cause ferroelectricity in the compound. This propagation was easily effected by the intrusion of molecules such as acetone into the structure.", "author_names": [ "Hiroki Okudera", "Yuka Sakai", "Ken-ichi Yamagata", "Hiroaki Takeda" ], "corpus_id": 49413588, "doc_id": "49413588", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Structure of russellite (Bi2WO6) origin of ferroelectricity and the effect of the stereoactive lone electron pair on the structure.", "venue": "Acta crystallographica Section B, Structural science, crystal engineering and materials", "year": 2018 }, { "abstract": "Development of sensor materials based on metal oxide semiconductors (MOS) for selective gas sensors is challenging for the tasks of air quality monitoring, early fire detection, gas leaks search, breath analysis, etc. An extensive range of sensor materials has been elaborated, but no consistent guidelines can be found for choosing a material composition targeting the selective detection of specific gases. Fundamental relations between material composition and sensing behavior have not been unambiguously established. In the present review, we summarize our recent works on the research of active sites and gas sensing behavior of n type semiconductor metal oxides with different composition (simple oxides ZnO, In2O3, SnO2, WO3; mixed metal oxides BaSnO3, Bi2WO6) and functionalized by catalytic noble metals (Ru, Pd, Au) The materials were variously characterized. The composition, metal oxygen bonding, microstructure, active sites, sensing behavior, and interaction routes with gases (CO, NH3, SO2, VOC, NO2) were examined. The key role of active sites in determining the selectivity of sensor materials is substantiated. It was shown that the metal oxygen bond energy of the MOS correlates with the surface acidity and the concentration of surface oxygen species and oxygen vacancies, which control the adsorption and redox conversion of analyte gas molecules. The effects of cations in mixed metal oxides on the sensitivity and selectivity of BaSnO3 and Bi2WO6 to SO2 and VOCs, respectively, are rationalized. The determining role of catalytic noble metals in oxidation of reducing analyte gases and the impact of acid sites of MOS to gas adsorption are demonstrated.", "author_names": [ "Artem Marikutsa", "Marina N Rumyantseva", "Elizaveta A Konstantinova", "Alexander Gaskov" ], "corpus_id": 233380862, "doc_id": "233380862", "n_citations": 5, "n_key_citations": 0, "score": 1, "title": "The Key Role of Active Sites in the Development of Selective Metal Oxide Sensor Materials", "venue": "Sensors", "year": 2021 }, { "abstract": "Molecular dynamical (MD) simulations were performed to study the structure sensitivity of H2O adsorption on adsorption different Bi2WO6 and grapheme supported Bi2WO6 surfaces. Results show that stronger interaction happens between H2O and Bi2WO6 (001) than the interactions (between H2O and Bi2WO6 (100) and between H2O and Bi2WO6 (010) and O atom of the surface acts as the active site for H2O adsorption. The adsorption modes and locations of H2O on G Bi2WO6 distinct with those on Bi2WO6 surfaces. The maximum adsorption amount of H2O on graphene is under 333K and 373K, with the value of 12.0403x10 5mol/m2 and 12.0538x10 5mol/m2. The maximum adsorption amount of H2O adsorption on Bi2WO6 (100) G Bi2WO6 (100) and G Bi2WO6 (001) is under 303K, 303K, and 333K, with 6.4079x10 5mol/m2, 9.1096x10 5mol/m2, and 11.1917x10 5mol/m2, respectively. Meanwhile, the maximum adsorption amount of H2O adsorption on G Bi2WO6 (010) is under 353K and 373K, with the value of 10.0452x10 5mol/m2 and 10.5417x10 5mol/m2. Results point out the optimal catalyst and the most appropriate pressure and temperature for H2O interacting to Bi2WO6 and grapheme supported Bi2WO6.", "author_names": [ "Xue Qing Hu", "Chen Lin", "Liang Tang", "Xunyong Liu" ], "corpus_id": 101368286, "doc_id": "101368286", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Structure Sensitivity of H2O Adsorption on Graphene Supported Bi2WO6", "venue": "", "year": 2013 }, { "abstract": "Immobilization of reduced graphene oxide (RGO) Bi2WO6 is an ideal method for obtaining antifouling membranes for membrane distillation (MD) processes. Poly(vinylidene fluoride) membranes modified with RGO Bi2WO6 were successfully obtained with a double layer coating method through non solvent induced phase separation. The water contact angle was improved by about 30deg by RGO Bi2WO6; this indicated that the surface modification obviously increased the membrane hydrophobicity. The high desalination rate proved that all of the prepared membranes were appropriate for the MD process. The RGO Bi2WO6 modified membranes achieve 26.26 59.95% removal rates in 10 mg/L aqueous ciprofloxacin under visible light for 7.5 h. It was possible to erase strongly bound foulants and recover the prepared membrane's permeation flux by 3 h of visible light irradiation. The RGO Bi2WO6 modified membrane with a high hydrophobicity, fouling mitigation, and photocatalytic capability presents huge potential for the treatment of high salt antibiotic wastewater use in the MD process. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45426.", "author_names": [ "Yukun Li", "Liang Zhu" ], "corpus_id": 136558847, "doc_id": "136558847", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Evaluation of the antifouling and photocatalytic properties of novel poly(vinylidene fluoride) membranes with a reduced graphene oxide Bi2WO6 active layer", "venue": "", "year": 2017 }, { "abstract": "Electrochemical reduction of CO2 to chemical fuel offers a promising strategy for managing the global carbon balance, but presents challenges for chemistry due to the lack of effective electrocatalyst. Here we report atomically dispersed nickel on nitrogenated graphene as an efficient and durable electrocatalyst for CO2 reduction. Based on operando X ray absorption and photoelectron spectroscopy measurements, the monovalent Ni(i) atomic center with a d9 electronic configuration was identified as the catalytically active site. The single Ni atom catalyst exhibits high intrinsic CO2 reduction activity, reaching a specific current of 350 A gcatalyst 1 and turnover frequency of 14,800 h 1 at a mild overpotential of 0.61 V for CO conversion with 97% Faradaic efficiency. The catalyst maintained 98% of its initial activity after 100 h of continuous reaction at CO formation current densities as high as 22 mA cm 2.Electrocatalysts with improved activity and stability for the conversion of CO2 to CO are being sought. Using operando spectroscopies, the authors identify atomically dispersed Ni(i) as the active site in a nitrogenated graphene supported catalyst with high intrinsic activity and stability over 100 hours.", "author_names": [ "Hong Bin Yang", "Sung-Fu Hung", "Song Liu", "Kaidi Yuan", "Shu Sean Miao", "Liping Zhang", "Xiang Huang", "Hsin-Yi Wang", "Weizheng Cai", "Rong Chen", "Jiajian Gao", "Xiaofeng Yang", "Wei Chen", "Yanqiang Huang", "Hao Ming Chen", "Chang Ming Li", "Tao Zhang", "Bin Liu" ], "corpus_id": 139757576, "doc_id": "139757576", "n_citations": 720, "n_key_citations": 0, "score": 0, "title": "Atomically dispersed Ni(i) as the active site for electrochemical CO2 reduction", "venue": "", "year": 2018 }, { "abstract": "Abstract The release of organic contaminant such as dye has become a major environmental issue. Bismuth tungstate (Bi2WO6) is one of the perovskites based photocatalysts shows a great ability to photodegrade organic dye under solar light irradiation. In this study, Bi2WO6 with different physicochemical properties was synthesized using one pot solvothermal method by varying the reaction temperature ranging from 120 degC to 180 degC. The Bi2WO6 synthesized at 140 degC (BWO 140) exhibited the highest photocatalytic activity (8.0 x 10 3 min 1) toward Erichrome Black T (EBT) dye. The superiority of Bi2WO6 photodegradation was mainly attributed to a synergistic effects of large surface area, small crystallite size, low electron recombination, and the presence of oxygen vacancies. Moreover, it was interesting to note that the BWO 140 could be reused for six consecutive cycles, without any significant deterioration. It was demonstrated that, photogenerated hole (h+ was the most important active species of Bi2WO6 to initiate the photocatalytic reaction.", "author_names": [ "Magdeline Tze Leng Lai", "Chin Wei Lai", "Kian Mun Lee", "Soon Wei Chook", "Thomas Chung-Kuang Yang", "Siewhui Chong", "Joon Ching Juan" ], "corpus_id": 197620816, "doc_id": "197620816", "n_citations": 30, "n_key_citations": 0, "score": 0, "title": "Facile one pot solvothermal method to synthesize solar active Bi2WO6 for photocatalytic degradation of organic dye", "venue": "Journal of Alloys and Compounds", "year": 2019 }, { "abstract": "The broad absorption range and high carrier separation efficiency of photocatalysts are important for improving photocatalytic performance. Herein, nitrogen doped graphene quantum dots (NGQDs) as effective active sites and collectors of charge carriers in modified Z scheme g C3N4/Bi2WO6 heterojunctions were obtained by a facile hydrothermal method, and dramatically enhanced the electron hole separation efficiency and light harvesting ability. NGQD modified Z scheme g C3N4/Bi2WO6 heterojunctions exhibited outstanding universal photocatalytic degradation activity for removing various antibiotics such as tetracycline (TC) ciprofloxacin (CIP) oxytetracyline (OTC) etc. under visible (vis) and near infrared (NIR) light irradiation owing to the charge carriers' collection effect and up conversion luminescence properties of NGQDs. In addition, the photocatalytic reaction mechanism was also revealed by active species trapping experiments and the electron spin resonance (ESR) technique, which indicated that the influencing order of active species on the photocatalytic reaction is .O2 h+ .OH.", "author_names": [ "Huinan Che", "Chunbo Liu", "Wei Hu", "Hao Hu", "Liu Jinqiao", "Jianying Dou", "Weidong Shi", "Chunmei Li", "Hongjun Dong" ], "corpus_id": 103944684, "doc_id": "103944684", "n_citations": 115, "n_key_citations": 0, "score": 0, "title": "NGQD active sites as effective collectors of charge carriers for improving the photocatalytic performance of Z scheme g C3N4/Bi2WO6 heterojunctions", "venue": "", "year": 2018 }, { "abstract": "Oxygen vacancy on the surface of metal oxides is one of the most important defects which acts as the reactive site in a variety of catalytic reactions. In this work, operando spectroscopy methodology was employed to study the CO2 methanation reaction catalyzed by Ru/CeO2 (with oxygen vacancy in CeO2) and Ru/a Al2O3 (without oxygen vacancy) respectively, so as to give a thorough understanding on active site dependent reaction mechanism. In Ru/CeO2 catalyst, operando XANES, IR, and Raman were used to reveal the generation process of Ce(3+ surface hydroxyl, and oxygen vacancy as well as their structural evolvements under practical reaction conditions. The steady state isotope transient kinetic analysis (SSITKA) type in situ DRIFT infrared spectroscopy undoubtedly substantiates that CO2 methanation undergoes formate route over Ru/CeO2 catalyst, and the formate dissociation to methanol catalyzed by oxygen vacancy is the rate determining step. In contrast, CO2 methanation undergoes CO route over Ru surface in Ru/a Al2O3 with the absence of oxygen vacancy, demonstrating active site dependent catalytic mechanism toward CO2 methanation. In addition, the catalytic activity evaluation and the oscillating reaction over Ru/CeO2 catalyst further prove that the oxygen vacancy catalyzes the rate determining step with a much lower activation temperature compared with Ru surface in Ru/a Al2O3 (125 vs 250 degC)", "author_names": [ "Fei Wang", "Shan He", "Hao Chen", "Bin Wang", "Lirong Zheng", "Min Wei", "David G Evans", "Xue Duan" ], "corpus_id": 34914640, "doc_id": "34914640", "n_citations": 252, "n_key_citations": 0, "score": 0, "title": "Active Site Dependent Reaction Mechanism over Ru/CeO2 Catalyst toward CO2 Methanation.", "venue": "Journal of the American Chemical Society", "year": 2016 } ]

[ { "abstract": "Ahardmask composition for forming a resist underlayer film, a process for producing a semiconductor integrated circuit device, and a semiconductor integrated circuit device, the hardmask composition including an organosilane polymer, and a stabilizer, the stabilizer including one of acetic anhy dride, methyl acetoacetate, propionic anhydride, ethyl 2ethylacetoacetate, butyric anhydride, ethyl 2 ethylacetoac etate, Valeric anhydride, 2 methylbutyric anhydride, nonanol, decanol, undecanol, dodecanol, propylene glycol propyl ether, propylene glycol ethyl ether, propylene glycol methyl ether, propylene glycol, phenyltrimethoxysilane, diphenyl hexamethoxydisiloxane, diphenylhexaethoxydisiloxane, dioctyltetramethyldisiloxane, hexamethyltrisiloxane, tetram ethyldisiloxane, decamethyltetrasiloxane, dodecamethylpen tasiloxane, hexamethyldisiloxane, and mixtures thereof.", "author_names": [ "Sang Kyun Kim" ], "corpus_id": 202587727, "doc_id": "202587727", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Photoresist layer Silicon based hardmask layer Carbon based hardmask layer Substrate", "venue": "", "year": 2017 }, { "abstract": "Stochastic defects in the photoresist profile are one of the main yield limiters in EUV lithography patterning. These stochastic defects can be, for example, local resist loss, resist profile footing, or resist scumming. A subset of these defects is transferred through the hardmask open (HMO) patterning, leading ultimately to electrical opens and shorts. We use on wafer data and process recipes to inform a physical etch model of the HMO process. This model is tested and confirmed by comparison to additional on silicon data. The established model provides a visualization of the defect transfer through individual process steps and highlights critical patterning steps that may limit electrical yield. For example, a change in in situ deposition time is observed to be more sensitive than oxide open or planarization film open times both in the model and on wafer. This provides us the insight to focus tuning deposition step times to reduce defectivity and improve process performance. Furthermore, this model provides insight into the type of defects which are eliminated during specific patterning steps, and the type of defects which are persistent and ultimately lead to electrical opens and shorts. To characterize these defects, we plant intentional defects with varying dimensions and study which ones stay through the entire HMO process and which ones are eliminated. This insight helps better understand the HMO process, which may lead in the future to further process improvements.", "author_names": [ "Dominik Metzler", "Mohamed Oulmane", "Sagarika Mukesh", "Philip J Stopford", "Karthik Yogendra", "Lawrence S Melvin" ], "corpus_id": 216327230, "doc_id": "216327230", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Simulation of photoresist defect transfer through subsequent patterning processes", "venue": "Advanced Lithography", "year": 2020 }, { "abstract": "A thick spin on carbon hardmask (SOH) material is designed to overcome inherent problems of amorphous deposited carbon layer (ACL) and thick photoresist. For ACL in use of semiconductor production process, especially when film thickness from sub micrometer up to few micrometers is required, not only its inherent low transparency at long wavelength light often causes alignment problems with under layers, but also considerable variation of film thickness within a wafer can also cause patterning problems. To avoid these issues, a thick SOH is designed with monomers of high transparency and good solubility at the same time. In comparison with photoresist, the SOH has good etch resistance and high thermal stability, and it provides wide process window of decreased film thickness and increased thermal budget up to 400degC after processes such as high temperature deposition of SiON. In order to achieve high thickness along with uniform film, many solvent factors was considered such as solubility parameter, surface tension, vapor pressure, and others. By optimizing many solvent factors, we were able to develop a product with a good coating performance", "author_names": [ "Taeho Kim", "Young-Min Kim", "Sunmin Hwang", "Hyunsoo Lee", "Miyeon Han", "Sanghak Lim" ], "corpus_id": 125192023, "doc_id": "125192023", "n_citations": 1, "n_key_citations": 0, "score": 1, "title": "Study on thick film spin on carbon hardmask", "venue": "Advanced Lithography", "year": 2017 }, { "abstract": "The present invention relates to a resist lower layer film as a hard mask composition. The present invention is an organic silane based polymer (A) And the resist lower layer film provides a hard mask composition that includes one or more stabilizing agent (B) Resist lower layer film as a hard mask composition of the present invention can transfer the fine pattern to the material layer to exhibit excellent storage stability and excellent hard mask properties. A hard mask, an organic silane based polymer, a stabilizer, the storage stability", "author_names": [ "" ], "corpus_id": 139976658, "doc_id": "139976658", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Hardmask Composition Coated under Photoresist with Improved Storage Stability", "venue": "", "year": 2008 }, { "abstract": "Abstract The study of the effects of photoresist thickness and the use of PECVD deposited oxide hard mask layer during source/drain high dose ion implantation process in the fabrication of ion sensitive field effect transistor (ISFET) is presented. Implementation of the new optimized process for the source/drain implant mask together with the improved process module have been successful in improving the threshold voltage (Vt) of the ISFET device from negative to more than 0.3 V. Consistent high ISFET yields of more than 90% were possible to achieve.", "author_names": [ "Nurhidaya Soriadi", "Azlina Mohd Zain", "Sharaifah Kamariah Wan Sabli", "Mohd Rofei Mat Hussin", "Hing Wah Lee" ], "corpus_id": 114654785, "doc_id": "114654785", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Study of Oxide Hardmask Effect on High Dose Implant Process for ISFET Fabrication", "venue": "", "year": 2017 }, { "abstract": "A hardmask composition for an under photoresist layer is provided to ensure excellent reproducibility of pattern and storage stability, good adhesion with a resist, and excellent solvent resistance for a developer used after exposing the resist, and to reduce film reduction in plasma etching. A hardmask composition for an under photoresist layer comprises an organic silane based polymer generated from a compound represented by the chemical formula 1; at least one selected from the group consisting of pyridinium p toluenesulfonate, amidosulfobetain 16, camphor 10 sulfonic acid ammonium salt, ammonium formate, triethylammonium formate, trimethyammonium formate, tetramethylammonium formate, pyridinium formate, tetrabutylammonium acetate, tetrabutylammonium azide, tetrabutylammonium benzoate, tetrabutylammonium bisulfate, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium cyanide, tetrabutylammonium fluoride, tetrabutylammonium iodide, tetrabutylammonium sulfate, tetrabutylammonium nitrate, tetrabutylammonium nitrite, tetrabutylammonium p toluenesulfonate and tetrabutylammonium phosphate; and solvent. In chemical formula 1, Rw, Rx, Ry and Rz are independently H or C1 5 alkyl; and n is an integer of 4 20.", "author_names": [ "" ], "corpus_id": 103460156, "doc_id": "103460156", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Hardmask composition for under photoresist layer; method of manufacturing semiconductor ic device therewith; and semiconductor ic device produced thereby", "venue": "", "year": 2007 }, { "abstract": "A hard mask composition for a photoresist under layer, and a method for preparing a semiconductor integrated circuit device by using the composition are provided to improve film characteristics and storage stability and to enhance the solvent resistance against a resist developer. A hard mask composition for a photoresist under layer comprises a silane condensate which is a condensation polymer of the hydrolyzate formed from at least one compound represented by the formula 1; an ammonium salt; and a solvent, wherein R1 is H, a substituted or unsubstituted C1 C30 aliphatic hydrocarbon group, a substituted or unsubstituted C1 C30 aromatic hydrocarbon group, a substituted or unsubstituted C1 C30 alicyclic hydrocarbon group, a substituted or unsubstituted C1 C30 silyl group, a substituted or unsubstituted C1 C30 allyl group, a substituted or unsubstituted C1 C30 acyl group, a vinyl group, an amine group, an acetate group, or an alkali metal; x is 0 2; and R2 is H, a substituted or unsubstituted C1 C4 aliphatic hydrocarbon group, an acetate group, Na, or K.", "author_names": [ "" ], "corpus_id": 103771294, "doc_id": "103771294", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Hardmask composition coated under photoresist and method for preparing semiconductor devices using thereof", "venue": "", "year": 2007 }, { "abstract": "Microelectromechanical Systems (MEMS) are a fast growing technology for sensor and actuator miniaturization finding more and more commercial opportunities by having an important role in the field of Internet of Things (IoT) On the same note, Fan out Wafer Level Packaging (FOWLP) namely WLFO technology of NANIUM, which is based on Infineon/ Intel eWLB technology, is also finding further applications, not only due to its high performance, low cost, high flexibility, but also due to its versatility to allow the integration of different types of components in the same small form factor package. Despite its great potential it is still off limits to the more sensitive components as micro mechanical devices and some type of sensors, which are vulnerable to temperature and pressure. In the interest of increasing FOWLP versatility and enabling the integration of MEMS, new methods of assembling and processing are continuously searched for. Dielectrics currently used for redistribution layer construction need to b.", "author_names": [ "R Leite Pinto", "Andre Cardoso", "S F Ribeiro", "Carlos Brandao", "Joao Gaspar", "Rizwan Gill", "Helder Fonseca", "Margaret Costa" ], "corpus_id": 115652201, "doc_id": "115652201", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Application of SU 8 photoresist as a multi functional structural dielectric layer in FOWLP", "venue": "", "year": 2017 }, { "abstract": "A hard mask composition for a lower layer of resist is provided to realize excellent film properties and shelf stability, to allow transfer of a high quality pattern to a substrate, and to form a hard mask having excellent etching resistance against O2 plasma gas used in the subsequent etching step. A hard mask composition for a lower layer of resist comprises: an organosilane based polymer produced from the compounds represented by the formula of [R1O]3Si X, [R2O]3Si R3 and [R4O]3Si Y Si[OR5]3 in the presence of an acid catalyst; and a solvent. In the formulae, X is a C6 C30 functional group containing a substituted or non substituted aromatic ring; each of R1, R2, R4 and R5 independently represents a C1 C6 alkyl; R3 is a C1 C12 alkyl; and Y is a linking group selected from an aromatic ring, C1 C20 linear or branched, substituted or non substituted alkylene, C1 C20 alkylene group whose backbone contains an aromatic ring, heterocyclic ring, urea or isocyanurate group, and C2 C20 hydrocarbon group containing a multiple bond.", "author_names": [ "" ], "corpus_id": 103131866, "doc_id": "103131866", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Hardmask composition coated under photoresist, process of producing integrated circuit devices using the same and semiconductor device produced by the process", "venue": "", "year": 2006 }, { "abstract": "A hard mask composition under a resist layer is provided to control the quantity of an alkoxy group of a final polycondensation material by adjusting the quantity of introduced water in a hydrolysis process of a compound. An organic silane based polymerization material has an alkoxy group generated from a compound designated by the following chemical formula 1 or an alkoxy group generated from compounds designated by the following chemical formulas 1 and 2. A hard mask composition includes the organic silane based polymerization material and a solvent. The organic silane based polymerization material is a polycondensation material of a hydrolytic material designated by the following chemical formula 3 that is obtained from the compound designated by the following chemical formula 1, or a polycondensation material of a hydrolytic material designated by the following chemical formulas 3 and 4 that are respectively obtained from the compounds designated by the following chemical formulas 1 and 2. Chemical formula 1 is [RO]3Si R' wherein R is methyl or ethyl and R' is substitution or non substitution alkyl of a ring or non ring shape. Chemical formula 2 is [RO]3Si Ar wherein R is methyl or ethyl and Ar is a functional group including an aromatic ring. Chemical formula 3 is R'Si[OR]n[OH]3 n wherein R is methyl or ethyl, R' is substitution or non substitution alkyl of a ring or non ring shape, and n is 0 3. Chemical formula 4 is ArSi[OR]n[OH]3 n wherein R is methyl or ethyl, Ar is a functional group including an aromatic ring, and n is 0 3.", "author_names": [ "" ], "corpus_id": 102590882, "doc_id": "102590882", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Hardmask composition coated under photoresist and process of producing integrated circuit devices using thereof", "venue": "", "year": 2006 } ]

[ { "abstract": "Significance Understanding and controlling the incorporation of metal into nanoscaled semiconductor is foundational for semiconductor processing. Through theoretical calculation and experimental results, we reveal that the interstitial atoms in the Si lattice such as Mn can quickly diffuse out of Si nanowires conveniently, thus can achieve high purity of Si nanowires. This finding of self inhibition effect not only provides understanding of impurity incorporation at nanoscale, but also provides an extra knob for rational catalyst designs of nanoscale building blocks, and fine tuning their electrical, optical, and thermal properties for various applications. There has been a persistent effort to understand and control the incorporation of metal impurities in semiconductors at nanoscale, as it is important for semiconductor processing from growth, doping to making contact. Previously, the injection of metal atoms into nanoscaled semiconductor, with concentrations orders of magnitude higher than the equilibrium solid solubility, has been reported, which is often deemed to be detrimental. Here our theoretical exploration reveals that this colossal injection is because gold or aluminum atoms tend to substitute Si atoms and thus are not mobile in the lattice of Si. In contrast, the interstitial atoms in the Si lattice such as manganese (Mn) are expected to quickly diffuse out conveniently. Experimentally, we confirm the self inhibition effect of Mn incorporation in nanoscaled silicon, as no metal atoms can be found in the body of silicon (below 1017 atoms per cm 3) by careful three dimensional atomic mappings using highly focused ultraviolet laser assisted atom probe tomography. As a result of self inhibition effect of metal incorporation, the corresponding field effect devices demonstrate superior transport properties. This finding of self inhibition effect provides a missing piece for understanding the metal incorporation in semiconductor at nanoscale, which is critical not only for growing nanoscale building blocks, but also for designing and processing metal semiconductor structures and fine tuning their properties at nanoscale.", "author_names": [ "Bin Zhu", "Ding Yi", "Yuxi Wang", "Hongyu Sun", "Gang Sha", "Gong Zheng", "Erik C Garnett", "Bozhi Tian", "Feng Ding", "Jia Zhu" ], "corpus_id": 231653370, "doc_id": "231653370", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Self inhibition effect of metal incorporation in nanoscaled semiconductors", "venue": "Proceedings of the National Academy of Sciences", "year": 2021 }, { "abstract": "The intricate and multifactorial nature of Alzheimer's disease (AD) requires the development of compounds able to hit different pathophysiological targets, such as cholinergic dysfunction, deposits of amyloid beta (Ab) peptide and metal dyshomeostasis. In order to continue the search for new anti AD drugs, a design strategy was once more followed based on repositioning donepezil (DNP) drug, by ortho attaching a benzylpiperidine mimetic of DNP moiety to a hydroxyphenyl benzimidazole (BIM) chelating unit (compound 1) Herein, compound 1 and a positional isomer 2 are compared in terms of their potential multiple properties: both present good acetylcholinesterase (AChE) inhibition (low mmolar range) and are moderate/good inhibitors of Ab self and Cu mediated aggregation, the inhibition process being mainly due to ligand intercalation between the b sheets of the fibrils; compound 1 has a higher chelating capacity towards Cu2+ and Zn2+ (pCu 14.3, pZn 6.4, pH 7.4, CL/CM 10, CM 10 6 M) than 2 (pCu 10.7, pZn 6.3) attributed to its ability to establish a tridentate (N,O,O) coordination to the metal ion. Both compounds are eligible as drug candidates for oral administration but compound 1 shows improved neuroprotective role by completely preventing Ab induced cell toxicity.", "author_names": [ "Marina Costa", "Romane Josselin", "Diana F Silva", "Sandra M Cardoso", "Nora Veronika May", "Silvia Chaves", "M Amelia Santos" ], "corpus_id": 212727931, "doc_id": "212727931", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Donepezil based hybrids as multifunctional anti Alzheimer's disease chelating agents: Effect of positional isomerization.", "venue": "Journal of inorganic biochemistry", "year": 2020 }, { "abstract": "The methods of quartz crystal microbalance, atomic force microscopy (AFM) scanning electron microscopy (SEM) Fourier transform IR spectroscopy, and X ray structural microanalysis were is used to show that adsorption of vinyl silane on an aluminum surface from an aqueous solution results in formation of a uniform, self organizing protective vinyl siloxane nanolayer covalently bound with surface metal groups. Its thickness can be controlled by variation of application conditions. The effect of a vinyl siloxane nanolayer on dissolution of aluminum is studied in chloride containing solutions. It is found that an ordered vinyl siloxane nanolayer with a thickness of up to 5 molecular layers causes efficient inhibition of uniform and local corrosion of aluminum. It is shown that the vinyl siloxane nanolayer is preserved on the surface of aluminum after 10 days of corrosion tests, which indicates its stability at exposure to water and corrosive components.", "author_names": [ "Maxim Petrunin", "L B Maksaeva", "Tatiana Yurasova", "E V Terekhova", "M A Maleeva", "A A Shcherbina", "V A Kotenev", "E N Kablov", "Aslan Yu Tsivadze" ], "corpus_id": 94546946, "doc_id": "94546946", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "The effect of self organizing vinyl siloxane nanolayers on the corrosion behavior of aluminum in neutral chloride containing solutions", "venue": "Protection of Metals and Physical Chemistry of Surfaces", "year": 2014 }, { "abstract": "To better understand how renal Na( reabsorption is altered by heavy metal poisoning, we examined the effects of several divalent heavy metal ions (Zn(2+ Ni(2+ Cu(2+ Pb(2+ Cd(2+ and Hg(2+ on the activity of single epithelial Na( channels (ENaC) in a renal epithelial cell line (A6) None of the cations changed the single channel conductance. However, ENaC activity [measured as the number of channels (N) x open probability (P(o) was decreased by Cd(2+ and Hg(2+ and increased by Cu(2+ Zn(2+ and Ni(2+ but was not changed by Pb(2+ Of the cations that induced an increase in Na( channel function, Zn(2+ increased N, Ni(2+ increased P(o) and Cu(2+ increased both. The cysteine modification reagent [2 (trimethylammonium)ethyl]methanethiosulfonate bromide also increased N, whereas diethylpyrocarbonate, which covalently modifies histidine residues, affected neither P(o) nor N. Cu(2+ increased N and stimulated P(o) by reducing Na( self inhibition. Furthermore, we observed that ENaC activity is slightly voltage dependent and that the voltage dependence of ENaC is insensitive to extracellular Na( concentration; however, apical application of Ni(2+ or diethylpyrocarbonate reduced the channel voltage dependence. Thus the voltage sensor of Xenopus ENaC is different from that of typical voltage gated channels, since voltage appears to be sensed by histidine residues in the extracellular loops of ENaC, rather than by charged amino acids in a transmembrane domain.", "author_names": [ "Ling Yu", "Douglas C Eaton", "My N Helms" ], "corpus_id": 23767255, "doc_id": "23767255", "n_citations": 27, "n_key_citations": 0, "score": 0, "title": "Effect of divalent heavy metals on epithelial Na+ channels in A6 cells.", "venue": "American journal of physiology. Renal physiology", "year": 2007 }, { "abstract": "A series of novel chalcone derivatives was designed, synthesized and evaluated as multifunctional agents for the treatment of AD. Among of these synthesized compounds, compound TM 2 was a selective BuChE inhibitor (IC50 2.6 mM) and selective MAO B inhibitor (IC50 5.3 mM) which were supported by docking study. Compound TM 2 also showed good antioxidant activity, and was a selective metal chelator, as well as a neuroprotectant. Moreover, compound TM 2 could significantly inhibit self induced and Cu2+ induced Ab1 42 aggregation with 70.2% and 80.7% inhibition rate, respectively, and could disaggregate Cu2+ induced Ab1 42 aggregation (73.5% the further TEM images observed provided rational explanation. Besides, compound TM 2 displayed good PAMPA BBB permeability and conformed to the Lipinski's rule of five. Further, compound TM 2 presented precognitive effect on scopolamine induced memory impairment in vivo assay. Therefore, compound TM 2 might be a promising multifunctional hit compound for the treatment of AD, and the further structure optimization are in progress.", "author_names": [ "Zhipei Sang", "Keren Wang", "Pengfei Zhang", "Jian Shi", "Wenmin Liu", "Zhenghuai Tan" ], "corpus_id": 197421542, "doc_id": "197421542", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Design, synthesis, in silico and biological evaluation of novel chalcone derivatives as multi function agents for the treatment of Alzheimer's disease.", "venue": "European journal of medicinal chemistry", "year": 2019 }, { "abstract": "In this work, we designed polysaccharide metal complex of dopamine modified pectin linking ruthenium compound, which exhibited a certain inhibition specificity to human renal cell adenocarcinoma cell line 786 O. The chemical structure and physical properties of the polysaccharide metal complex were well characterized by multiple analysis methods. The multi spectral results revealed that pectin dopamine have been successfully coordinated by ruthenium complex to form nano conjugates, which self assembled into relatively regular nanospheres of approximately 200 nm. The polysaccharide metal complex has more amorphous and less viscosity than pectin, and cannot withstand as much strain as the pectin and pectin dopamine systems. Pectin dopamine can decrease the toxicity effect of Ru complex in normal cell line such as human normal renal epithelial cell line 293A.", "author_names": [ "Jiajing Diao", "Feng Bai", "Ying Wang", "Qianqian Han", "Xi Xu", "Hongmei Zhang", "Qiang Luo", "Yanqing Wang" ], "corpus_id": 56149902, "doc_id": "56149902", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Engineering of pectin dopamine nano conjugates for carrying ruthenium complex: A potential tool for biomedical applications.", "venue": "Journal of inorganic biochemistry", "year": 2019 }, { "abstract": "A series of scutellarein O alkylamine derivatives were designed, synthesized and tested as multifunctional agents for the treatment of Alzheimer's disease (AD) The results showed that most of these compounds exhibited good multifunctional activities. Among them, compound 16d demonstrated significant metal chelating properties, moderate acetylcholinesterase (AChE) inhibitory and anti oxidative activity, and excellent inhibitory effects on self induced Ab(1 42) aggregation, Cu(2+ induced Ab(1 42) aggregation, human AChE induced Ab(1 40) aggregation and disassembled Cu(2+ induced aggregation of the well structured Ab(1 42) fibrils. Both kinetic analysis of AChE inhibition and molecular modeling study suggested that 16d binds simultaneously to the catalytic active site and peripheral anionic site of AChE. Moreover, compound 16d showed a good protective effect against H2O2 induced PC12 cell injury, with low toxicity in SH SY5Y cells. Furthermore, the step down passive avoidance test showed this compound significantly reversed scopolamine induced memory deficit in mice. Thus, 16d was shown to be an interesting multifunctional lead compound worthy of further study.", "author_names": [ "Zhipei Sang", "Xiaoming Qiang", "Yan Li", "Wen Yuan", "Q Liu", "Yikun Shi", "Wei Ang", "Youfu Luo", "Zhenghuai Tan", "Yong Deng" ], "corpus_id": 23806161, "doc_id": "23806161", "n_citations": 49, "n_key_citations": 0, "score": 0, "title": "Design, synthesis and evaluation of scutellarein O alkylamines as multifunctional agents for the treatment of Alzheimer's disease.", "venue": "European journal of medicinal chemistry", "year": 2015 }, { "abstract": "We use hydrodynamical simulations from the OverWhelmingly Large Simulations (OWLS) project to investigate the dependence of the physical properties of galaxy populations at redshift 2 on metal line cooling and feedback from star formation and active galactic nuclei (AGN) We find that if the sub grid feedback from star formation is implemented kinetically, the feedback is only efficient if the initial wind velocity exceeds a critical value. This critical velocity increases with galaxy mass and also if metal line cooling is included. This suggests that radiative losses quench the winds if their initial velocity is too low. If the feedback is efficient, then the star formation rate is inversely proportional to the amount of energy injected per unit stellar mass formed (which is proportional to the initial mass loading for a fixed wind velocity) This can be understood if the star formation is self regulating, i.e. if the star formation rate (and thus the gas fraction) increases until the outflow rate balances the inflow rate. Feedback from AGN is efficient at high masses, while increasing the initial wind velocity with gas pressure or halo mass allows one to generate galaxy wide outflows at all masses. Matching the observed galaxy mass function requires efficient feedback. In particular, the predicted faint end slope is too steep unless we resort to highly mass loaded winds for low mass objects. Such efficient feedback from low mass galaxies (M* 1010 M) also reduces the discrepancy with the observed specific star formation rates, which are higher than predicted unless the feedback transitions from highly efficient to inefficient just below M* 5 x 109 M.", "author_names": [ "Marcel Richard Haas", "Joop Schaye", "Craig M Booth", "Claudio Dalla Vecchia", "Volker Springel", "Tom Theuns", "Robert P C Wiersma Rutgers University", "Leiden Observatory", "", "University of Chicago", "Kavli Institute for Cosmological Physics", "Enrico Fermi Institute", "Heidelberger Institut fur Theoretische Studien", "Heidelberg Northwestern University", "University of Durham", "University of Antwerp" ], "corpus_id": 54038403, "doc_id": "54038403", "n_citations": 59, "n_key_citations": 3, "score": 0, "title": "Physical properties of simulated galaxy populations at z=2 I. Effect of metal line cooling and feedback from star formation and AGN", "venue": "", "year": 2013 }, { "abstract": "Abstract For the first time, Feldspar (F) nanocontainer, which is a group of rock forming tectosilicate minerals with the chemical composition of KAlSi3O8 NaAlSi3O8 CaAl2Si2O8, was used for the construction of an epoxy composite coating with superior barrier and self healing anti corrosion performance. Feldspar (F) based nanocontainer with robust corrosion inhibitive activity was fabricated through the encapsulation of zinc cations as a cathodic inhibitor. It was understood from the electrochemical measurements that in the saline solution including F/Zn extract the metal corrosion was significantly retarded (by protection efficiency of 73% due to the inhibitor release activity of the F/Zn container and protective film generation on the metal surface. The inductively coupled plasma (ICP) analysis results confirmed the Zn2+ cations (5.33 mg/L) release in the chloride solution from the F/Zn container. EIS test results evidenced the significant effect of the F/Zn in the epoxy ester composite coating barrier and self healing anti corrosion functions in the intact and scratched forms. In the presence of F/Zn an improvement in the charge transfer resistance (about 83% of the scratched coating was observed, indicating the active self healing inhibition effect of the F/Zn nanocarrier. By incorporation of the F/Zn particles into the epoxy ester coating the E' (at 30 degC) glass transition temperature (Tg) stress, strain and energy at break were significantly enhanced. These results proved that not only the corrosion protection properties but also the mechanical properties of the epoxy ester coating were excellently improved in the presence of F/Zn nanocarrier.", "author_names": [ "M M Davoodi", "Esmaeil Ghasemi", "Bahram Ramezanzadeh", "Mohammad Mahdavian" ], "corpus_id": 214104133, "doc_id": "214104133", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Designing a zinc encapsulated Feldspar as a unique rock forming tectosilicate nanocontainer in the epoxy coating; improving the robust barrier and self healing anti corrosion properties", "venue": "", "year": 2020 }, { "abstract": "Electroless deposition (ELD) is widely used in industry to deposit metals because it is inexpensive and compatible with organic materials. The deposition rate and deposited film properties critically depend on the reducing agent, complexing agent, and bath pH and temperature as well as bath additives. We have investigated the role of ethanolamine additives in the ELD of copper using the reducing agent dimethylamine borane on CH3 and OH terminated self assembled monolayers (SAMs) adsorbed on gold. Three additives were studied: ethanolamine (EOA) diethanolamine (DEOA) and triethanolamine (TEOA) Both the chemical identity and concentration of the ethanolamine significantly affect the deposition process. We show that the Cu deposition rate is faster on CH3 terminated surfaces than on OH terminated SAMs because of the stronger interaction of the ethanolamines with the hydroxyl terminal group. In contrast to physical vapor deposition and other ELD processes, Cu deposits atop methyl terminated SAMs using TEOA. However, using EOA and DEOA, copper penetrates through CH3 terminated SAMs to the Au/S interface. For OH terminated SAMs, copper is observed to penetrate through the SAM for all ethanolamines investigated. The amount of copper penetration through the SAM to the Au/S interface increases with ethanolamine concentration. These effects are attributed to an adsorption inhibition mechanism and differences in the chelation of Cu2+ in the deposition bath.", "author_names": [ "Ashley A Ellsworth", "Amy V Walker" ], "corpus_id": 4391343, "doc_id": "4391343", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Effect of Ethanolamines on the Electroless Deposition of Copper on Functionalized Organic Surfaces.", "venue": "Langmuir the ACS journal of surfaces and colloids", "year": 2018 } ]

[ { "abstract": "Two dimensional materials are attractive for use in next generation nanoelectronic devices because, compared to one dimensional materials, it is relatively easy to fabricate complex structures from them. The most widely studied two dimensional material is graphene, both because of its rich physics and its high mobility. However, pristine graphene does not have a bandgap, a property that is essential for many applications, including transistors. Engineering a graphene bandgap increases fabrication complexity and either reduces mobilities to the level of strained silicon films or requires high voltages. Although single layers of MoS(2) have a large intrinsic bandgap of 1.8 eV (ref. 16) previously reported mobilities in the 0.5 3 cm(2) V( 1) s( 1) range are too low for practical devices. Here, we use a halfnium oxide gate dielectric to demonstrate a room temperature single layer MoS(2) mobility of at least 200 cm(2) V( 1) s( 1) similar to that of graphene nanoribbons, and demonstrate transistors with room temperature current on/off ratios of 1 x 10(8) and ultralow standby power dissipation. Because monolayer MoS(2) has a direct bandgap, it can be used to construct interband tunnel FETs, which offer lower power consumption than classical transistors. Monolayer MoS(2) could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.", "author_names": [ "Branimir Radisavljevic", "Aleksandra Radenovic", "Jacopo Brivio", "Valentina Giacometti", "Andras Kis" ], "corpus_id": 205446552, "doc_id": "205446552", "n_citations": 9689, "n_key_citations": 117, "score": 1, "title": "Single layer MoS2 transistors.", "venue": "Nature nanotechnology", "year": 2011 }, { "abstract": "A new phototransistor based on the mechanically exfoliated single layer MoS(2) nanosheet is fabricated, and its light induced electric properties are investigated in detail. Photocurrent generated from the phototransistor is solely determined by the illuminated optical power at a constant drain or gate voltage. The switching behavior of photocurrent generation and annihilation can be completely finished within ca. 50 ms, and it shows good stability. Especially, the single layer MoS(2) phototransistor exhibits a better photoresponsivity as compared with the graphene based device. The unique characteristics of incident light control, prompt photoswitching, and good photoresponsivity from the MoS(2) phototransistor pave an avenue to develop the single layer semiconducting materials for multifunctional optoelectronic device applications in the future.", "author_names": [ "Zongyou Yin", "Hai Li", "Hong Li", "Lin Jiang", "Yumeng Shi", "Yinghui Sun", "Gang Lu", "Qing Yu Zhang", "Xiaodong Chen", "Hua Zhang" ], "corpus_id": 27038582, "doc_id": "27038582", "n_citations": 2570, "n_key_citations": 16, "score": 0, "title": "Single layer MoS2 phototransistors.", "venue": "ACS nano", "year": 2012 }, { "abstract": "Molybdenum disulfide (MoS(2) of single and few layer thickness was exfoliated on SiO(2)/Si substrate and characterized by Raman spectroscopy. The number of S Mo S layers of the samples was independently determined by contact mode atomic force microscopy. Two Raman modes, E(1)(2g) and A(1g) exhibited sensitive thickness dependence, with the frequency of the former decreasing and that of the latter increasing with thickness. The results provide a convenient and reliable means for determining layer thickness with atomic level precision. The opposite direction of the frequency shifts, which cannot be explained solely by van der Waals interlayer coupling, is attributed to Coulombic interactions and possible stacking induced changes of the intralayer bonding. This work exemplifies the evolution of structural parameters in layered materials in changing from the three dimensional to the two dimensional regime.", "author_names": [ "Changgu Lee", "Hugen Yan", "Louis E Brus", "Tony F Heinz", "James C Hone", "Sunmin Ryu" ], "corpus_id": 6543876, "doc_id": "6543876", "n_citations": 3172, "n_key_citations": 44, "score": 0, "title": "Anomalous lattice vibrations of single and few layer MoS2.", "venue": "ACS nano", "year": 2010 }, { "abstract": "Ubiquitous low frequency 1/f noise can be a limiting factor in the performance and application of nanoscale devices. Here, we quantitatively investigate low frequency electronic noise in single layer transition metal dichalcogenide MoS2 field effect transistors. The measured 1/f noise can be explained by an empirical formulation of mobility fluctuations with the Hooge parameter ranging between 0.005 and 2.0 in vacuum <10( 5) Torr) The field effect mobility decreased, and the noise amplitude increased by an order of magnitude in ambient conditions, revealing the significant influence of atmospheric adsorbates on charge transport. In addition, single Lorentzian generation recombination noise was observed to increase by an order of magnitude as the devices were cooled from 300 to 6.5 K.", "author_names": [ "Vinod K Sangwan", "Heather N Arnold", "Deep Jariwala", "Tobin J Marks", "Lincoln J Lauhon", "Mark C Hersam" ], "corpus_id": 14803449, "doc_id": "14803449", "n_citations": 193, "n_key_citations": 3, "score": 0, "title": "Low frequency electronic noise in single layer MoS2 transistors.", "venue": "Nano letters", "year": 2013 }, { "abstract": "While there has been growing interest in two dimensional (2 D) crystals other than graphene, evaluating their potential usefulness for electronic applications is still in its infancy due to the lack of a complete picture of their performance potential. The focus of this article is on contacts. We demonstrate that through a proper understanding and design of source/drain contacts and the right choice of number of MoS(2) layers the excellent intrinsic properties of this 2 D material can be harvested. Using scandium contacts on 10 nm thick exfoliated MoS(2) flakes that are covered by a 15 nm Al(2)O(3) film, high effective mobilities of 700 cm(2)(V s) are achieved at room temperature. This breakthrough is largely attributed to the fact that we succeeded in eliminating contact resistance effects that limited the device performance in the past unrecognized. In fact, the apparent linear dependence of current on drain voltage had mislead researchers to believe that a truly Ohmic contact had already been achieved, a misconception that we also elucidate in the present article.", "author_names": [ "Saptarshi Das", "Hong-Yan Chen", "Ashish Verma Penumatcha", "Joerg Appenzeller" ], "corpus_id": 17348762, "doc_id": "17348762", "n_citations": 1718, "n_key_citations": 38, "score": 0, "title": "High performance multilayer MoS2 transistors with scandium contacts.", "venue": "Nano letters", "year": 2013 }, { "abstract": "Logic circuits and the ability to amplify electrical signals form the functional backbone of electronics along with the possibility to integrate multiple elements on the same chip. The miniaturization of electronic circuits is expected to reach fundamental limits in the near future. Two dimensional materials such as single layer MoS(2) represent the ultimate limit of miniaturization in the vertical dimension, are interesting as building blocks of low power nanoelectronic devices, and are suitable for integration due to their planar geometry. Because they are less than 1 nm thin, 2D materials in transistors could also lead to reduced short channel effects and result in fabrication of smaller and more power efficient transistors. Here, we report on the first integrated circuit based on a two dimensional semiconductor MoS(2) Our integrated circuits are capable of operating as inverters, converting logical \"1\" into logical \"0\" with room temperature voltage gain higher than 1, making them suitable for incorporation into digital circuits. We also show that electrical circuits composed of single layer MoS(2) transistors are capable of performing the NOR logic operation, the basis from which all logical operations and full digital functionality can be deduced.", "author_names": [ "Branimir Radisavljevic", "Michael Brian Whitwick", "Andras Kis" ], "corpus_id": 7161527, "doc_id": "7161527", "n_citations": 995, "n_key_citations": 6, "score": 0, "title": "Integrated circuits and logic operations based on single layer MoS2.", "venue": "ACS nano", "year": 2011 }, { "abstract": "Abstract MoS 2 has been exfoliated into monolayers by intercalation with lithium followed by reaction with water. X ray diffraction analysis has shown that the exfoliated MoS 2 in suspension is in the form of one molecule thick sheets. X ray patterns from dried and re stacked films of exfoliated MoS 2 indicate that the layers are randomly stacked. Exfoliated MoS 2 has been deposited on alumina particles in aqueous suspension, enabling recovery of dry exfoliated MoS 2 supported on alumina.", "author_names": [ "Per Joensen", "R F Frindt", "Stanley Roy Morrison" ], "corpus_id": 96081624, "doc_id": "96081624", "n_citations": 960, "n_key_citations": 5, "score": 0, "title": "Single layer MoS2", "venue": "", "year": 1986 }, { "abstract": "Based on first principles plane wave calculations, we studied the functionalization of the two dimensional single layer MoS2 structure through adatom adsorption and vacancy defect creation. Minimum energy adsorption sites were determined for 16 different adatoms, each of which gives rise to diverse properties. Bare, single layer MoS2, which is normally a nonmagnetic, direct band gap semiconductor, attains a net magnetic moment upon adsorption of specific transition metal atoms, as well as silicon and germanium atoms. The localized donor and acceptor states in the band gap expand the utilization of MoS2 in nanoelectronics and spintronics. Specific adatoms, such as C and O, attain significant excess charge upon adsorption onto single layer MoS2, which might be useful for tribological applications. Each MoS2 triple vacancy created in a single layer of MoS2 gives rise to a net magnetic moment, whereas other vacancy defects related to Mo and S atoms do not influence the nonmagnetic ground state. The present re.", "author_names": [ "Can Ataca", "Salim Ciraci" ], "corpus_id": 95029274, "doc_id": "95029274", "n_citations": 394, "n_key_citations": 2, "score": 0, "title": "Functionalization of Single Layer MoS2 Honeycomb Structures", "venue": "", "year": 2010 }, { "abstract": "We have studied using scanning tunneling microscopy (STM) the atomic scale realm of molybdenum disulfide MoS2) nanoclusters, which are of interest as a model system in hydrodesulfurization catalysis. The STM gives the first real space images of the shape and edge structure of single layer MoS2 nanoparticles synthesized on Au(111) and establishes a new picture of the active edge sites of the nanoclusters. The results demonstrate a way to get detailed atomic scale information on catalysts in general.", "author_names": [ "" ], "corpus_id": 29647963, "doc_id": "29647963", "n_citations": 655, "n_key_citations": 9, "score": 0, "title": "Atomic scale structure of single layer MoS2 nanoclusters", "venue": "Physical review letters", "year": 2000 }, { "abstract": "Two dimensional materials are an emerging class of new materials with a wide range of electrical properties and potential practical applications. Although graphene is the most well studied two dimensional material, single layers of other materials, such as insulating BN (ref. 2) and semiconducting MoS2 (refs 3, 4) or WSe2 (refs 5, 6) are gaining increasing attention as promising gate insulators and channel materials for field effect transistors. Because monolayer MoS2 is a direct bandgap semiconductor due to quantum mechanical confinement, it could be suitable for applications in optoelectronic devices where the direct bandgap would allow a high absorption coefficient and efficient electron hole pair generation under photoexcitation. Here, we demonstrate ultrasensitive monolayer MoS2 phototransistors with improved device mobility and ON current. Our devices show a maximum external photoresponsivity of 880 A W( 1) at a wavelength of 561 nm and a photoresponse in the 400 680 nm range. With recent developments in large scale production techniques such as liquid scale exfoliation and chemical vapour deposition like growth, MoS2 shows important potential for applications in MoS2 based integrated optoelectronic circuits, light sensing, biomedical imaging, video recording and spectroscopy.", "author_names": [ "Oriol Lopez-Sanchez", "Dominik S Lembke", "M Kayci", "Aleksandra Radenovic", "Andras Kis" ], "corpus_id": 5435971, "doc_id": "5435971", "n_citations": 3092, "n_key_citations": 33, "score": 0, "title": "Ultrasensitive photodetectors based on monolayer MoS2.", "venue": "Nature nanotechnology", "year": 2013 } ]

[ { "abstract": "In 1972, Fujishima and Honda discovered the photocatalytic splitting of water on TiO{sub 2} electrodes. This event marked the beginning of a new era in heterogeneous photocatalysis. Since then, research efforts in understanding the fundamental processes and in enhancing the photocatalytic efficiency of TiO{sub 2} have come from extensive research performed by chemists, physicists, and chemical engineers. Such studies are often related to energy renewal and energy storage. In recent years, applications to environmental cleanup have been one of the most active areas in heterogeneous photocatalysis. This is inspired by the potential application of TiO{sub 2} based photocatalysts for the total destruction of organic compounds in polluted air and wastewaters. There exists a vast body of literature dealing with the electron transfer and energy transfer processes in photocatalytic reactions. A detailed description of these processes is beyond the scope of this review. Here, the authors tend to focus on interfacial processes and to summarize some of the operating principles of heterogeneous photocatalysis. In section 2, the authors first look at the electronic excitation processes in a molecule and in a semiconductor substrate. The electronic interaction between the adsorbate molecule and the catalyst substrate is discussed in terms of the catalyzed ormore sensitized photoreactions. In section 3, thermal and photocatalytic studies on TiO{sub 2} are summarized with emphasis on the common characteristics and fundamental principles of the TiO{sub 2} based photocatalysis systems. In section 4, they address the research effort in the electronic modification of the semiconductor catalysts and its effect on the photocatalytic efficiency. Several representative examples will be presented including the Schottky barrier formation and modification at metal semiconductor interfaces. Some concluding remarks and future research directions will be given in the final section. 160 refs. less", "author_names": [ "A L Linsebigler", "Guang Lu", "John T Yates" ], "corpus_id": 53343077, "doc_id": "53343077", "n_citations": 9478, "n_key_citations": 89, "score": 1, "title": "Photocatalysis on TiO2 Surfaces: Principles, Mechanisms, and Selected Results", "venue": "", "year": 1995 }, { "abstract": "Photocatalysis has been widely applied in various areas, such as solar cells, water splitting, and pollutant degradation. Therefore, the photochemical mechanisms and basic principles of photocatalysis, especially TiO2 photocatalysis, have been extensively investigated by various surface science methods in the last decade, aiming to provide important information for TiO2 photocatalysis under real environmental conditions. Recent progress that provides fundamental insights into TiO2 photocatalysis at a molecular level is highlighted. Insights into the structures of TiO2 and the basic principles of TiO2 photocatalysis are discussed first, which provides the basic concepts of TiO2 photocatalysis. Following this, details of the photochemistry of three important molecules (oxygen, water, methanol) on the model TiO2 surfaces are presented, in an attempt to unravel the relationship between charge/energy transfer and bond breaking/forming in TiO2 photocatalysis. Lastly, challenges and opportunities of the mechanistic studies of TiO2 photocatalysis at the molecular level are discussed briefly, as well as possible photocatalysis models.", "author_names": [ "Qing Guo", "Chuanyao Zhou", "Zhibo Ma", "Xueming Yang" ], "corpus_id": 201062711, "doc_id": "201062711", "n_citations": 200, "n_key_citations": 0, "score": 0, "title": "Fundamentals of TiO2 Photocatalysis: Concepts, Mechanisms, and Challenges.", "venue": "Advanced materials", "year": 2019 }, { "abstract": "The use of sunlight to drive chemical reactions via photocatalysis is of paramount importance towards a sustainable future. Among several photocatalysts, earth abundant polymeric carbon nitride (PCN, often wrongly named g C3N4) has emerged as an attractive candidate due to its ability to absorb light efficiently in the visible and near infrared ranges, chemical stability, non toxicity, straightforward synthesis, and versatility as a platform for constructing hybrid materials. Especially, hybrids with metal nanoparticles offer the unique possibility of combining the catalytic, electronic, and optical properties of metal nanoparticles with PCN. Here, we provide a comprehensive overview of PCN materials and their hybrids, emphasizing heterostructures with metal nanoparticles. We focus on recent advances encompassing synthetic strategies, design principles, photocatalytic applications, and charge transfer mechanisms. We also discuss how the localized surface plasmon resonance (LSPR) effect of some noble metals NPs (e.g. Au, Ag, and Cu) bimetallic compositions, and even non noble metals NPs (e.g. Bi) synergistically contribute with PCN in light driven transformations. Finally, we provide a perspective on the field, in which the understanding of the enhancement mechanisms combined with truly controlled synthesis can act as a powerful tool to the establishment of the design principles needed to take the field of photocatalysis with PCN to a new level, where the desired properties and performances can be planned in advance, and the target material synthesized accordingly.", "author_names": [ "Ivo Freitas Teixeira", "Eduardo C M Barbosa", "Shik Chi Edman Tsang", "Pedro H C Camargo" ], "corpus_id": 206130858, "doc_id": "206130858", "n_citations": 105, "n_key_citations": 0, "score": 0, "title": "Carbon nitrides and metal nanoparticles: from controlled synthesis to design principles for improved photocatalysis.", "venue": "Chemical Society reviews", "year": 2018 }, { "abstract": "Catalysts are involved at some stage in the manufacture process of virtually all commercially produced chemical product. Among the materials used as catalysts, metal oxides are one of the most used due to their versatility and wide range of physical properties. Identifying the principles of surface to adsorbate charge transfer is key to a better understanding of metal oxide materials as both catalysts and gas sensors. Using density functional theory (DFT) we modeled the adsorption of small molecules over stoichiometric and reduced metal oxide surfaces of group IV metals and quantify the effect of electron transfer upon adsorption. We found that charge transfer only occurs during the adsorption process of an adsorbate more electronegative than the surface. We also found a correlation between the work function of the metal oxide, and the ionic adsorption of the oxygen molecule. Mixed phase rutile/anatase catalysts show increased reactivity compared with the pure phases alone. However, the mechanism causing this effect is not fully understood. Using DFT and the +U correction we calculated the bands offsets between the phases taking into account the effect of the interface. We found rutile to have both higher conduction and valence band offsets than anatase, leading to an accumulation of electrons in the anatase phase accompanied by hole accumulation in the rutile phase. We also probed the electronic structure of our heterostructure and found a gap state caused by electrons localized in undercoordinated Ti atoms which were present within the interfacial region. Interfaces between bulk materials and between exposed surfaces both showed electron trapping at undercoordinated sites. Finally, we studied the effect of the size of gold nanoparticles in the catalytic properties of gold decorated TiO2 surfaces. We found that the adsorption energy of several intermediates reactives in the CO oxidation and water gas shift reaction does not change with the size of the nanoparticles. In conclusion, the factor that affects the reactivity of the system is the density of undercoodinated gold atoms on the interface perimeter.", "author_names": [ "Juan Carlos Abanades Garcia" ], "corpus_id": 139950684, "doc_id": "139950684", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Catalysis and Photocatalysis over TiO2 Surfaces Detailed from First Principles", "venue": "", "year": 2014 }, { "abstract": "Abstract An abundant and largely available natural energy resource is sunlight, which possesses great potential in driving environment friendly photochemical/photocatalytic reactions. The conversion of solar energy to chemical energy has been considered as one of the most prospective long term solutions to solve global energy and environmental issues. The photocatalyst is the key to realize such a conversion. Common photocatalytic materials include metal free organic compounds and semiconductors, in which most of the interest has been focused on the semiconductor system. A photocatalyst employs the catalyst for speeding up chemical reactions in the presence of light. Significant features of the photocatalytic systems are proper bandgap, the morphology of the material, more exposed surface area, stability, and its reusability. Photocatalysis is widely being practised for the degradation and mineralization of hazardous organic compounds to CO2 and H2O. Thus, leads to the reduction of toxic metal ions into nontoxic states, deactivate and destruct all the waterborne microorganisms, decomposes the air pollutants like NO2, CO2, and NH3, degraded the waste plastics and green synthesis of industrially important chemicals. The term chalcogen applies to a few elements (O, S, Se, Te, and Po) the compounds formed by these elements are known as chalcogenides and also some chalcogenide metals (ZnS, CdS, and CdSe) can be used as photocatalysts, which is an area of present day intensive research. ZnO and TiO2 are the most commonly used metal oxides for photocatalytic and sensing purposes, due to their outstanding properties and potential electronic communicator. Semiconducting nano metal oxides (NMOs) play an important role in developing smart materials that are highly efficient for sensing and simultaneously decontaminate harmful chemicals in our environment. As the material loading plays an important role in photocatalytic performances, physical mixture through grounding is the most straightforward approach to realize transition metal oxide and chalcogenide (TMO&Cs) based heterojunctions. In this chapter, the authors discussed the unique properties, significance of chalcogenide based nanomaterials, principles and fundamentals as photocatalysts. Methods of synthesis like sol gel method, ultrasonic method, hydro (solvo) thermal method, surfactant thermal method, and in situ photo assisted deposition method, and other nonconventional synthesis methodologies, and mechanisms of chalcogenide based nanomaterials as photocatalysts were also discussed along with their applications.", "author_names": [ "G V S S Sarma", "Murthy Chavali", "Maria Nikolova", "Manoj Kumar Enamala", "Chandrasekar Kuppan" ], "corpus_id": 234898362, "doc_id": "234898362", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Basic principles, fundamentals, and mechanisms of chalcogenide based nanomaterials in photocatalytic reactions", "venue": "", "year": 2021 }, { "abstract": "Photocatalysis method for environmental applications has been using for a long time. This review article traces back the origin of catalysis, its classification and journey of development to heterogeneous photocatalysis and the article's novelty is in the simplicity, and easily understandable language, designed for the beginners. These heterogeneous photocatalysts are grouped into eleven different categories. As the paper is focused on photocatalysis, an insight on fundamental principles and mechanisms of photocatalysis are explained systematically with schematic illustrations and reactions that take place during redox oxidation and reduction reactions in photocatalysis. With an approach towards utilizing green energy and expanding the photocatalyst' absorption wavelength range towards the visible regime, bandgap engineering techniques by adopting doping and hetero structures are explained with examples of different materials. In addition, dominating factors of photocatalysis reaction viz. composition of a heterogeneous photocatalyst, doping, hetero structures, pH, surface defects on photocatalysis reaction are explored, focussing on variable charge transfer mechanisms. The main influencing factor in generating reactive oxygen species is pH of the photocatalysis reaction and are studied indetail. The effect of alkalinity or acidity in catalyst surfaces and molecular interaction depending upon the point zero charges of the photocatalyst are discussed. For the better study of catalyst properties, careful analysis and study is a much needed field as a scope for further improvement. Hence, this article will guide a beginner to understand the photocatalysis topic with ease.", "author_names": [ "Debika Devi Thongam", "Harsh Chaturvedi" ], "corpus_id": 233833919, "doc_id": "233833919", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Advances in nanomaterials for heterogeneous photocatalysis", "venue": "", "year": 2021 }, { "abstract": "Preceding work on photoelectrochemistry at semiconductor single crystal electrodes has formed the basis for the tremendous growth in the three last decades in the field of photocatalysis at semiconductor powders. The reason for this is the unique ability of inorganic semiconductor surfaces to photocatalyze concerted reduction and oxidation reactions of a large variety of electron donor and acceptor substrates. Whereas great attention was paid to water splitting and the exhaustive aerobic degradation of pollutants, only a small amount of research also explored synthetic aspects. After introducing the basic mechanistic principles, standard experiments for the preparation and characterization of visible light active photocatalysts as well as the investigation of reaction mechanisms are discussed. Novel atom economic C C and C N coupling reactions illustrate the relevance of semiconductor photocatalysis for organic synthesis, and demonstrate that the multidisciplinary field combines classical photochemistry with electrochemistry, solid state chemistry, and heterogeneous catalysis.", "author_names": [ "Horst Kisch" ], "corpus_id": 24265857, "doc_id": "24265857", "n_citations": 516, "n_key_citations": 2, "score": 0, "title": "Semiconductor photocatalysis mechanistic and synthetic aspects.", "venue": "Angewandte Chemie", "year": 2013 }, { "abstract": "Photochemical reactions induced by TiO2 nanoparticles share common mechanistic features where electron and hole pairs are formed, migrate to the surface, and their recombination competes with their reaction with various substrates. The main interest in TiO2 photocatalysis is related to its potential application for decontamination of water and air. However, the absorption of TiO2, which is limited to UV light, does not enable the use of natural or cheap light sources, and therefore tremendous effort has been invested in inducing visible light activity via modification of TiO2 including doping with nonmetals and metals, surface coating, and bi and multicomponent assembling. In addition, much research has been carried out to inhibit the electron hole recombination and enhance the reactions of holes and electrons with substrates. The basic mechanism of bare and modified TiO2 and the main principles of the photocatalytic processes remain similar, although the excitation energy is different and the energies of the electrons and holes and their reaction kinetic parameters may vary. These photocatalytic processes are reviewed and discussed.", "author_names": [ "Joseph Rabani", "Sara Goldstein" ], "corpus_id": 91630746, "doc_id": "91630746", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Mechanisms of Reactions Induced by Photocatalysis of Titanium Dioxide Nanoparticles", "venue": "", "year": 2013 }, { "abstract": "Abstract In recent years, although several two dimensional materials such as graphene, graphitic carbon nitride, and transition metal dichalcogenides have been explored in energy and environmental applications, MXenes have obtained more importance because of their excellent stability and cost effectiveness and they allow the functionalization of surface moieties. This chapter discusses various methods used for the synthesis of MXenes and MXenes based photocatalysts for hydrogen evolution and degradation of organic pollutants with recent findings and advancements in this field. After a brief introduction to the types of MXenes and their structure, general principles of photocatalysis, mechanism involved in hydrogen production, and organic pollutant degradation processes have been explained in detail. The focus is mainly on the idea behind the design and development of MXenes based photocatalysts along with enhancement in photocatalytic activity. Finally, a summary is given to the recent findings and development of MXenes based photocatalysts in order to utilize the visible light region of sunlight and future perspective of this material is discussed at the end.", "author_names": [ "Vishal Sharma", "Ashish Kumar", "Venkata Krishnan" ], "corpus_id": 213224756, "doc_id": "213224756", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Two dimensional MXene based heterostructures for photocatalysis", "venue": "", "year": 2020 }, { "abstract": "Solar driven water splitting provides a leading approach to store the abundant yet intermittent solar energy and produce hydrogen as a clean and sustainable energy carrier. A straightforward route to light driven water splitting is to apply self supported particulate photocatalysts, which is expected to allow solar hydrogen to be competitive with fossil fuel derived hydrogen on a levelized cost basis. More importantly, the powder based systems can lend themselves to making functional panels on a large scale while retaining the intrinsic activity of the photocatalyst. However, all attempts to generate hydrogen via powder based solar water splitting systems to date have unfortunately fallen short of the efficiency values required for practical applications. Photocatalysis on photocatalyst particles involves three sequential steps: (i) absorption of photons with higher energies than the bandgap of the photocatalysts, leading to the excitation of electron hole pairs in the particles, (ii) charge separation and migration of these photoexcited carriers, and (iii) surface chemical reactions based on these carriers. In this review, we focus on the challenges of each step and summarize material design strategies to overcome the obstacles and limitations. This review illustrates that it is possible to employ the fundamental principles underlying photosynthesis and the tools of chemical and materials science to design and prepare photocatalysts for overall water splitting.", "author_names": [ "Qingming Wang", "Kazunari Domen" ], "corpus_id": 199505199, "doc_id": "199505199", "n_citations": 373, "n_key_citations": 1, "score": 0, "title": "Particulate Photocatalysts for Light Driven Water Splitting: Mechanisms, Challenges, and Design Strategies.", "venue": "Chemical reviews", "year": 2019 } ]

[ { "abstract": "Unlike traditional passive harmonic filters, modern active harmonic filters have the following multiple functions: harmonic filtering, damping,isolation and termination, reactive power control for power factor correction and voltage regulation, load balancing, voltage flicker reduction, and/or their combinations. Significant cost reductions in both power semiconductor devices and signal processing devices have inspired manufactures to put active filters on the market. This paper deals with general pure active filters for power conditioning, and specific hybrid active filters for harmonic filtering of three phase diode rectifiers.", "author_names": [ "Hirofumi Akagi" ], "corpus_id": 44594581, "doc_id": "44594581", "n_citations": 960, "n_key_citations": 42, "score": 0, "title": "Active Harmonic Filters", "venue": "Proceedings of the IEEE", "year": 2005 }, { "abstract": "The interest in variable speed multiphase induction motor drives has substantially increased in recent years and novel proposals show good prospects for industrial implementation in high power applications. The additional degrees of freedom existing in multiphase machines have allowed for new applications with high torque density by current harmonic injection in concentrated winding machines. This paper addresses, for the first time, the bifurcation analysis of a five phase induction motor drive when a third harmonic is injected for torque enhancement purposes. The main focus of this paper is to present a mathematically based study of the nonlinear dynamics of the proposed drive with torque enhancement. The overall bifurcation analysis for both concentrated and distributed winding machines confirms that the harmonic injection provides not only torque enhancement but also more robust controllers. This further advantage offers improved performance of multiphase drives compared to their three phase counterparts.", "author_names": [ "Mario Javier Duran", "Francisco Salas", "Manuel Ruiz Arahal" ], "corpus_id": 34746178, "doc_id": "34746178", "n_citations": 142, "n_key_citations": 0, "score": 0, "title": "Bifurcation Analysis of Five Phase Induction Motor Drives With Third Harmonic Injection", "venue": "IEEE Transactions on Industrial Electronics", "year": 2008 }, { "abstract": "It is well known that vacuum tube amplifiers and solid state amplifiers sound different. An important factor accounting for the difference is output harmonic contents. This paper describes a novel analog method to change the harmonic contents of a signal. Based on this method, a transistor amplifier with controllable output harmonics has been built. Performance has been evaluated by both objective measurements and subjective listening.", "author_names": [ "Jerry C F Li" ], "corpus_id": 211688861, "doc_id": "211688861", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Using Transistors to Emulate Vacuum Tube Sound Quality Based on Asymmetric Cycle Harmonic Injection Method", "venue": "2019 IEEE 8th Global Conference on Consumer Electronics (GCCE)", "year": 2019 }, { "abstract": "Over recent years, the output power of micro inverters [module incorporated inverter (MIC) is progressively pushed to higher levels, following the current photovoltaic (PV) modules market trends. The interleaved Flyback inverter under discontinuous conduction mode of operation (DCM) is an appealing solution for PV applications which are based on MIC technology. This topology provides increased power level for distributed PV generation exploitation with simple control configuration, high efficiency, and reduced filter size. In this paper, the harmonic injection capability is incorporated into the interleaved Flyback inverter for the implementation of an active anti islanding scheme. A suitable technical solution is proposed that bypasses the unfolding H bridge, without affecting the active power generation of the inverter and without requiring any hardware modification. In addition, a mathematical model based on the instantaneous power balance theory is presented, being a powerful analysis tool for inverters operating under complete magnetic discharge such as the Flyback inverter (either conventional or interleaved) under DCM or boundary conduction mode of operation. The proposed model predicts accurately the steady state operational behavior of the Flyback inverter under current harmonic injection, either in grid tied or islanding operation. The proposed technical implementation method and mathematical model are verified through simulation and experimental results. Finally, an anti islanding set up based on the proposed harmonic injection technique is presented and implemented into the Flyback micro inverter. The proposed set up is verified through experimental results on various quality factor values, as well as for weak grid conditions.", "author_names": [ "Dionisis Voglitsis", "Nick P Papanikolaou", "Anastasios Ch Kyritsis" ], "corpus_id": 33650139, "doc_id": "33650139", "n_citations": 37, "n_key_citations": 3, "score": 0, "title": "Incorporation of Harmonic Injection in an Interleaved Flyback Inverter for the Implementation of an Active Anti Islanding Technique", "venue": "IEEE Transactions on Power Electronics", "year": 2017 }, { "abstract": "Square wave voltage injection is an effective sensorless control method for permanent magnet synchronous motor drives to achieve zero or low speed operation. However, it faces great challenge in the case of rail transit application where the switching frequency is less than or equal to 500 Hz, which results in rich low order harmonics. In order to improve the performance of high frequency square wave voltage injection method over low switching frequency application, an asymmetric space vector modulation (ASVM) method is proposed, and it makes comparisons between carrier and modulation wave in the 1/4 and 3/4 point of each switching cycle. Compared with space vector modulation, ASVM can significantly reduce the low order sideband and baseband harmonics in the bandpass filter bandwidth. As a result, the position estimation, which is calculated by the filtered current signal, is improved. Moreover, the inverter dead time effect has been compensated as well. With these improvements, the rotor position can be estimated without using low pass filters and its dynamic performance can be enhanced. The experimental results proved the effectiveness of the analysis.", "author_names": [ "Hang Zhang", "Weiguo Liu", "Zhe Chen", "Guangzhao Luo", "Jianxing Liu", "Dongdong Zhao" ], "corpus_id": 3973751, "doc_id": "3973751", "n_citations": 32, "n_key_citations": 0, "score": 0, "title": "Asymmetric Space Vector Modulation for PMSM Sensorless Drives Based on Square Wave Voltage Injection Method", "venue": "IEEE Transactions on Industry Applications", "year": 2018 }, { "abstract": "This paper presents an active harmonic elimination method to eliminate any number of specific higher order harmonics of multilevel converters with equal or unequal dc voltages. First, resultant theory is applied to transcendental equations characterizing the harmonic content to eliminate low order harmonics and to determine switching angles for the fundamental frequency switching scheme and a unipolar switching scheme. Next, the residual higher order harmonics are computed and subtracted from the original voltage waveform to eliminate them. The simulation results show that the method can effectively eliminate the specific harmonics, and a low total harmonic distortion (THD) near sine wave is produced. An experimental 11 level H bridge multilevel converter with a field programmable gate array controller is employed to implement the method. The experimental results show that the method does effectively eliminate any number of specific harmonics, and the output voltage waveform has low THD.", "author_names": [ "", "Leon M Tolbert", "John N Chiasson" ], "corpus_id": 14577499, "doc_id": "14577499", "n_citations": 334, "n_key_citations": 10, "score": 0, "title": "Active harmonic elimination for multilevel converters", "venue": "IEEE Transactions on Power Electronics", "year": 2006 }, { "abstract": "A low jitter, low power LC based injection locked clock multiplier (ILCM) with a digital frequency tracking loop (FTL) is presented. Based on a pulse gating technique, the proposed FTL continuously tunes the oscillator's free running frequency to ensure robust operation across PVT variations. The FTL resolves the race condition existing in injection locked PLLs by decoupling frequency tuning from the injection path, such that the phase locking condition is only determined by the injection path. This paper also introduces an accurate theoretical large signal analysis for phase domain response (PDR) of injection locked oscillators (ILOs) The proposed PDR analysis captures the asymmetric nature of ILO's lock in range, and the impact of frequency error on injection strength and phase noise performance. The proposed architecture and analysis are demonstrated by a prototype fabricated in 65 nm CMOS process with active area of 0.25 mm2. The prototype ILCM generates output clock in the range of 6.75 8.25 GHz by multiplying the reference clock by 64. It achieves superior integrated jitter performance of 190 fsrms, while consuming 2.25 mW power. This translates to an excellent figure of merit (FoM) of 251 dB, which is the best reported high frequency clock multiplier.", "author_names": [ "Ahmed Elkholy", "Mrunmay Talegaonkar", "Tejasvi Anand", "Pavan Kumar Hanumolu" ], "corpus_id": 19958957, "doc_id": "19958957", "n_citations": 36, "n_key_citations": 8, "score": 0, "title": "Design and Analysis of Low Power High Frequency Robust Sub Harmonic Injection Locked Clock Multipliers", "venue": "IEEE Journal of Solid State Circuits", "year": 2015 }, { "abstract": "Injection locking characteristics of oscillators are derived and a graphical analysis is presented that describes injection pulling in time and frequency domains. An identity obtained from phase and envelope equations is used to express the requisite oscillator nonlinearity and interpret phase noise reduction. The behavior of phase locked oscillators under injection pulling is also formulated.", "author_names": [ "Behzad Razavi" ], "corpus_id": 6095408, "doc_id": "6095408", "n_citations": 1014, "n_key_citations": 71, "score": 0, "title": "A study of injection locking and pulling in oscillators", "venue": "IEEE Journal of Solid State Circuits", "year": 2004 }, { "abstract": "This paper presents a reduced switching frequency active harmonic elimination method (RAHEM) to eliminate any number of specific order harmonics of multilevel converters. First, resultant theory is applied to transcendental equations to eliminate low order harmonics and to determine switching angles for a fundamental frequency switching scheme. Next, based on the number of harmonics to be eliminated, Newton climbing method is applied to transcendental equations to eliminate high order harmonics and to determine switching angles for the fundamental frequency switching scheme. Third, the magnitudes and phases of the residual lower order harmonics are computed, generated, and subtracted from the original voltage waveform to eliminate these low order harmonics. Compared to the active harmonic elimination method (AHEM) which generates square waves to cancel high order harmonics, RAHEM has lower switching frequency. The simulation results show that the method can effectively eliminate all the specific harmonics, and a low total harmonic distortion (THD) near sine wave is produced. An experimental 11 level H bridge multilevel converter with a field programmable gate array controller is employed to experimentally validate the method. The experimental results show that RAHEM does effectively eliminate any number of specific harmonics, and the output voltage waveform has low switching frequency and low THD.", "author_names": [ "Zhong Du", "Leon M Tolbert", "John N Chiasson", "Burak Ozpineci" ], "corpus_id": 2284754, "doc_id": "2284754", "n_citations": 107, "n_key_citations": 5, "score": 0, "title": "Reduced Switching Frequency Active Harmonic Elimination for Multilevel Converters", "venue": "IEEE Transactions on Industrial Electronics", "year": 2008 }, { "abstract": "Preface Introduction Harmonic Analysis Harmonic Sources The Static Convertor Other Harmonic Sources Harmonic Effects: Within the Power System Interference with Communications Power System Harmonic Measurements Transducers and Data Transmission Standards for the Limitation and Control of Power System Harmonics Harmonic Penetration in A.C. Systems Harmonic Elimination Index.", "author_names": [ "Jos Arrillaga", "David A Bradley", "Pat S Bodger" ], "corpus_id": 108174716, "doc_id": "108174716", "n_citations": 928, "n_key_citations": 30, "score": 0, "title": "Power System Harmonics", "venue": "", "year": 2003 } ]

[ { "abstract": "Gallium oxide has recently been found to be of high interest as the widest bandgap semiconductor for which single crystals bulk substrates are available and whose electronic conductivity can be controlled by n type doping. Because wide bandgap semiconductors lead to high breakdown voltages in small length scales, and the resistive losses over small length scales are low, the material has several attractive attributes for high voltage electronic diodes and switches. In this chapter, I give a personal account of the materials science and physics of this exciting new semiconductor material and its initial use in device demonstrations. The intention of the personal account is to share the twisted and connected paths that lead one to a specific research direction this is certainly true for how I ended up being interested in gallium oxide as an interesting semiconductor material.", "author_names": [ "Debdeep Jena" ], "corpus_id": 219048326, "doc_id": "219048326", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Gallium Oxide Materials and Devices", "venue": "", "year": 2020 }, { "abstract": "Beta gallium oxide (Ga2O3) has received much attention recently as a viable candidate for the nextgeneration material for power electronics and photonic applications, with its unique advantages, such as the wide bandgap 4.9 eV) high breakdown voltage, and optical transparency up to UV range. Recent advances in high quality Ga2O3 thin film growth, such as using molecular beam epitaxy or chemical vapor deposition, combined with the material's availability as inexpensive bulk substrates have opened new exciting opportunities for the fabrication of novel Ga2O3 devices. Despite the advances, many of the fundamental properties of Ga2O3 are yet to be understood clearly. As in many other oxide based transparent semiconductors, point defects and their complexes can dictate the properties of Ga2O3. Various spectroscopic methods as well as theoretical calculations have provided useful insights on the nature of the point defects and complexes in Ga2O3. Regardless, what has been missing in the field is the detailed information on the atomic scale structure of the defects and complexes in Ga2O3. Such information is crucial to determine how the atomic scale defects relate to many of the unanswered questions regarding the unique properties of Ga2O3, including how point defects and impurity atoms influence the formation of trap states, how the dopant atoms are compensated, and what is the exact origin of the difficulty in doping of Ga2O3 (especially p type)", "author_names": [ "Jared M Johnson", "Hsien-Lien Huang", "Jinwoo Hwang" ], "corpus_id": 225391199, "doc_id": "225391199", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Point Defects and Complexes in Gallium Oxide Materials and Devices", "venue": "Microscopy and Microanalysis", "year": 2020 }, { "abstract": "", "author_names": [ "Stephen J Pearton", "Fan Ren", "Jihyun Kim", "Michael Stavola", "A Y Polyakov" ], "corpus_id": 225189643, "doc_id": "225189643", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Radiation damage in gallium oxide materials and devices", "venue": "", "year": 2020 }, { "abstract": "In this talk, we provide an overview overview of our work on beta Ga2O3 growth, doping, heterostructures and devices. In plasma assisted MBE growth of beta Ga2O3 we demonstrate the differences in growth on cleavage (e.g. (100) vs. non cleavage planes (e.g. (010) or (001) the propensity for growth rate limitations by suboxide formation. We demonstrate unintentional doping concentration in the mid10E15 cm 3 range, and controllable intentional doping with electron concentrations from 10E16 to >10E20 cm 3. We review the development and characterization of coherent (Al,Ga)2O3/Ga2O3 heterostructures and demonstration of modulation doping and MODFETs.", "author_names": [ "James S Speck" ], "corpus_id": 139699270, "doc_id": "139699270", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Progress in beta gallium oxide materials and devices (Conference Presentation)", "venue": "", "year": 2018 }, { "abstract": "This introductory chapter provides current and comprehensive information about gallium oxide, covering crystal structures, basic physical properties, bulk melt growth and thin film epitaxial growth methods, and representative electrical and optical devices.", "author_names": [ "Masataka Higashiwaki", "Shizuo Fujita Editors", "Shizuo Fujita" ], "corpus_id": 216085513, "doc_id": "216085513", "n_citations": 10, "n_key_citations": 1, "score": 0, "title": "Gallium Oxide: Materials Properties, Crystal Growth, and Devices", "venue": "", "year": 2020 }, { "abstract": "Gallium Oxide is an ultra wide band gap semiconductor that provides key benefits for high performance power devices, including high electric breakdown field strength, good transport properties, well controlled doping, and large area melt grown native substrates. The unique properties of this material also provide significant opportunities for heterostructure and device engineering. In this paper, we discuss some key advances toward achieving high performance devices based on Gallium Oxide, and discuss future opportunities and challenges in this exciting area of research.", "author_names": [ "Zhanbo Xia", "Nidhin Kurian Kalarickal", "Siddharth Rajan" ], "corpus_id": 233226339, "doc_id": "233226339", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Materials and Device Engineering for High Performance Gallium Oxide Devices", "venue": "2020 IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium (BCICTS)", "year": 2020 }, { "abstract": "", "author_names": [ "Fan Ren", "Rajendra Singh", "Stephen J Pearton", "Jihyun Kim", "A Y Polyakov", "Steven A Ringel", "Renxu Jia" ], "corpus_id": 195427414, "doc_id": "195427414", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Preface JSS Focus Issue on Gallium Oxide Based Materials and Devices", "venue": "", "year": 2019 }, { "abstract": "", "author_names": [ "Shoya Fujita" ], "corpus_id": 140046037, "doc_id": "140046037", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Evolution and Prospects of Gallium Oxide Based Materials and Power Devices", "venue": "", "year": 2018 }, { "abstract": "", "author_names": [ "Debdeep Jena" ], "corpus_id": 138641217, "doc_id": "138641217", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Invited) Gallium Oxide Based Materials and Devices", "venue": "", "year": 2016 }, { "abstract": "", "author_names": [ "Xutang Tao", "Jiandong Ye", "Shibing Long", "Zhitai Jia" ], "corpus_id": 115297691, "doc_id": "115297691", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Preface to the Special Issue on Ultra Wide Bandgap Semiconductor Gallium Oxide: from Materials to Devices", "venue": "", "year": 2019 } ]

[ { "abstract": "Heusler compounds are promising materials in many fields of contemporary research. The spectrum of their possible applications ranges from magnetic and magneto mechanical materials over semiconductors and thermoelectrics to superconductors. An important feature of the Heusler compounds is the possibility of controlling the valence electron concentration by partial substitution of elements. On the other hand, the properties also depend on the degree of ordering of the the crystal structure. In general, Heusler compounds crystallize in the Cu2MnAl type structure but in many cases certain types of disorder are observed. In this paper a detailed description of the different types of disordered structures is given. Additionally, the synthesis of new Heusler compounds is reported. The prepared compounds contain ternary Cr Rh Ru Ni Pd and Pt based Heusler systems as well as quaternary Co2 based compounds and compounds of the general formula XXYZ. The crystal structure was determined by XRD measurements and the structural ordering of the compounds is discussed.", "author_names": [ "Tanja Graf", "Frederick Casper", "Juergen Winterlik", "Benjamin Balke", "Gerhard H Fecher", "Claudia Felser" ], "corpus_id": 93869650, "doc_id": "93869650", "n_citations": 92, "n_key_citations": 0, "score": 1, "title": "Crystal Structure of New Heusler Compounds", "venue": "", "year": 2009 }, { "abstract": "The present work reports on the new soft ferromagnetic Heusler phases Fe2NiGe, Fe2CuGa, and Fe2CuAl, which in previous theoretical studies have been predicted to exist in a tetragonal regular Heusler structure. Together with the known phases Fe2CoGe and Fe2NiGa these materials have been synthesized and characterized by powder XRD, 57 Fe M\\\"ossbauer spectroscopy, SQUID and EDX measurements. In particular M\\\"ossbauer spectroscopy was used to monitor the degree of local atomic order/disorder and to estimate magnetic moments at the Fe sites from the hyperfine fields. It is shown that in contrast to the previous predictions all the materials except Fe2NiGa basically adopt the inverse cubic Heusler (X structure with differing degrees of disorder. The disorder is more enhanced in case of Fe2NiGa, which was predicted as an inverse Heusler phase. The experimental data are compared with results from ab inito electronic structure calculations on LDA level incorporating the effects of atomic disorder by using the coherent potential approximation (CPA) A good agreement between calculated and experimental magnetic moments is found for the cubic inverse Heusler phases. Model calculations on various atomic configurations demonstrate that antisite disorder tends to enhance the stability of the X structure. Given the fundamental scientific and technological importance of tetragonal Heusler phases the present results call for further investigations to unravel the factors stabilizing tetragonal Heusler materials.", "author_names": [ "Teuta Gasi", "Vadim Ksenofontov", "Janos Kiss", "Stanislav Chadov", "Ajaya K Nayak", "Michael Nicklas", "Juergen Winterlik", "Michael Schwall", "Peter Klaer", "Peter Adler", "Claudia Felser" ], "corpus_id": 118313523, "doc_id": "118313523", "n_citations": 68, "n_key_citations": 1, "score": 0, "title": "Iron based Heusler compounds Fe2YZ: Comparison with theoretical predictions of the crystal structure and magnetic properties", "venue": "", "year": 2013 }, { "abstract": "Abstract The crystal structure, electronic and magnetic properties of predicted new full Heusler compounds Zr 2 MnZ (Z=Al, Ga, In) were studied within the density functional theory (DFT) framework. These materials exhibit unique properties that connect the spin gapless semiconducting character with the completely compensated ferrimagnetism. Magnetically ordered Zr 2 MnZ (Z=Al, Ga, In) compounds crystallize in inverse Heusler structure are stable against decomposition and have zero magnetic moment per formula unit, in agreement with Slater Pauling rule. The Zr 2 MnAl compound presents semiconducting properties with an energy band gap of 0.41 eV in the majority spin channel and a zero band gap in the minority spin channel. By substituting completely the Al in Zr 2 MnAl via Ga and In elements, semiconducting pseudo band gaps are formed in the majority spin channels due to different neighborhoods around the manganese atoms, which decreases the energy of Mn triple degenerated anti bonding states.", "author_names": [ "A Birsan" ], "corpus_id": 119221524, "doc_id": "119221524", "n_citations": 35, "n_key_citations": 0, "score": 0, "title": "First principle investigations of the structural, electronic and magnetic properties of predicted new zirconium based full Heusler compounds, Zr2MnZ (Z=Al, Ga and In)", "venue": "", "year": 2016 }, { "abstract": "In this work, half metallic (HM) properties of new Half Heusler (HH) ferromagnetic compounds CrTiX (X Si, Ge, Sn, Pb) are studied by means of first principle band structure calculation within the framework of density functional theory (DFT) From the spin polarized calculations using full potential linearized augmented plane wave (FP LAPW)method, we found that all of these compounds are stable in ferromagnetic MgAgAs type crystal structure. The latticeparameters of CrTiX compounds increase with increasing atomic radius of X atom and ranges from 5.76 to 6.38 A. The calculated electronic structure of these compounds in MgAgAs type structure shows that they are HM materials with an integer magnetic moment of 4 mB. Densities of states, electronic band structure, and origin of ferromagnetism have been discussed, and robust HM nature of these compounds is analyzed which makes them fascinating compounds for spintronic devices.", "author_names": [ "Muhammad Atif Sattar", "Muhammad Aamer Rashid", "Muhammad Nasir Rasool", "Asif Mahmood", "Muhammad Raza-ur-rehman Hashmi", "S Aftab Ahmad", "Muhammad Imran", "Fayyaz Hussain" ], "corpus_id": 123935068, "doc_id": "123935068", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Half Metallic Ferromagnetism in New Half Heusler Compounds: an Ab Initio Study of CrTiX (X Si, Ge, Sn, Pb)", "venue": "", "year": 2016 }, { "abstract": "Mn2 based Heusler compounds have attracted a great deal of interest as half metallic ferri and ferromagnets and as materials for spintronic applications. In this paper, we report the synthesis, crystal structure, and disorder type of the new Heusler compounds Mn2RuGe, Mn2RhGa, and the redetermination of the crystal structure of Mn2RuSn. They crystallize cubic with L21b structure type in Fmm, which is an inverse Heusler structure with a transition metal disorder of the type (Mn0.5,Y0.5)2MnZ (Y Ru or Rh and Z Ge, Ga or Sn) It is shown that an inverse Heusler structure can generally gain stability through the configurational part of the entropy of mixing at elevated temperatures without loosing too much enthalpy in the configurational part of the enthalpy of mixing owing to a special bond arrangement in the inverse type structure. The enthalpy of formation of transition metal based Heusler compounds and Al, Ga, and Ge as the main group metals obtained from DFT calculations and experimental data are used to confirm Burch's rule, which predicts the stability of transition metal based inverse Heusler compounds. Alloying tendencies as manifested in binary phase diagrams and the enthalpies obtained from the Miedema model are correlated with the stability of Heusler compounds. Burch's rule is in excellent agreement with the current available experimental data. The DFT data and general alloying tendencies show that deviations are expected from this rule. Miedema's model allows the estimation of the enthalpy of formation for the transition and main group metal based Heusler compounds, except for those having period 6 elements and Pd.", "author_names": [ "Guido Kreiner", "Adel Kalache", "Steffen Hausdorf", "Vajiheh Alijani", "J F Qian", "Guangcun Shan", "Ulrich Burkhardt", "Siham Ouardi", "Claudia Felser" ], "corpus_id": 98429207, "doc_id": "98429207", "n_citations": 51, "n_key_citations": 0, "score": 0, "title": "New Mn2 based Heusler Compounds+", "venue": "", "year": 2014 }, { "abstract": "Abstract Based on the previous research and summary, a new half metallic Heusler alloy FeCrAs have been proposed. The density functional theory of spin polarization is calculated by using the first principles calculation software CASTEP to determine the lattice constants of FeCrAs compounds in half Heusler structure. The effect of each element on its half metallicity and the formation of band gap are calculated. The total magnetic moment is calculated and verified theoretically. The range of lattice distortion which keeps half metallic properties was studied to ensure its half metallic properties. In the calculation process, the role of Fe atom in the crystal cell, based on the theory of level splitting in the crystal field of the complexes, has been studied. According to the calculations, the FeCrAs compound of Half Heusler phase is a new Heusler alloy.", "author_names": [ "Zhaopeng Hao", "Ran Liu", "Yihang Fan", "Lili Wang" ], "corpus_id": 214530931, "doc_id": "214530931", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "First principles calculations of a new half metallic Heusler alloy FeCrAs", "venue": "", "year": 2020 }, { "abstract": ".i ACKNOWLEDGMENTS..iii DEDICATION .iv LIST OF TABLE..viii LIST OF FIGURES..ix CHAPTER 1 INTRODUCTION..1 1.1 Spin Polarization..3 1.2 Half Metals..5 1.3 Thesis statement..7 1.4 Thesis Outline..8 CHAPTER 2 THEORETICAL BACKGROUND..9 2.1 Heusler Compounds..9 2.2 .1 Crystal Structure of Heusler Alloys..11 2.2 X ray Diffraction for Determination of Crystal Structure..13 2.2.1 Structure Factor (F).14 vi 2.2.2 X ray Diffraction Pattern for the Order and Disorder Heusler Compounds..15 2.3 Magnetism and magnetic Properties of Heusler Compounds..18 2.4 Literature Review..21 CHAPTER 3 EXPERIMENTAL TECHNIQUES..24 3.1 Sample Preparation..24 3.2 X ray Diffraction Measurements..26 3.3 Metallography..28 3.4 Magnetization Measurements..29 CHAPTER 4 RESULTS AND DISCUSSIONS..31 4.1 Mn2CoZ Family..31 4.1.1 Mn2CoGa..31 A. The crystal structure of Mn2CoGa..31 B. The Magnetic Properties of the Mn2CoGa..36 C. The Microstructure of Mn2CoGa..40 4.1.2 Mn2CoGe and Mn2CoSb..41 4.2 Mn2FeZ Family..44 4.2.1 Mn2FeSi..44 A. The Crystal Structure of Mn2FeSi..44 B. The Microstructure of Mn2FeSi..50 4.2.2 Mn2FeGe..51 CHAPTER 5 CONCLUSION..53 REFERENCES..56", "author_names": [ "Said Bakkar" ], "corpus_id": 139516099, "doc_id": "139516099", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "NEW INVERSE HEUSLER MATERIALS WITH POTENTIAL SPINTRONICS APPLICATIONS", "venue": "", "year": 2017 }, { "abstract": "Crystalline solids are characterized by periodic structures, resulting in a diverse assortment of crystal structures that exhibit a wide variety of properties. Here we report short range order, which results in characteristic diffuse bands in electron diffraction patterns, in a series of defective 19 electron half Heusler compounds for the first time. The co existence of the vacancy related short range order and the crystalline long range periodic structure makes these defective half Heusler compounds promising thermoelectric materials with low thermal conductivity and high electrical conductivity simultaneously. This new finding provides important insights into the intrinsic nature of defective HH compounds, and also proposes a possible strategy for tuning the degree of ordering to offer great potential for further improvement of thermoelectrics.", "author_names": [ "Kaiyang Xia", "Pengfei Nan", "Shihua Tan", "Yumei Wang", "Binghui Ge", "Wenqing Zhang", "Shashwat Anand", "Xinbing Zhao", "Gerald Jeffrey Snyder", "Tiejun Zhu" ], "corpus_id": 146013875, "doc_id": "146013875", "n_citations": 30, "n_key_citations": 1, "score": 0, "title": "Short range order in defective half Heusler thermoelectric crystals", "venue": "", "year": 2019 }, { "abstract": "Electronic structure theory has recently been used to propose hypothetical compounds in presumed crystal structures, seeking new useful functional materials. In some cases, such hypothetical materials are metastable, albeit with technologically useful long lifetimes. Yet, in other cases, suggested hypothetical compounds may be signifi cantly higher in energy than their lowest energy crystal structures or competing phases, making their synthesis and eventual device stability questionable. By way of example, the focus here is on the family of 1:1:1 compounds ABX called \"fi lled tetrahedral structure\" (sometimes called Half Heusler) in the four groups with octet electron count: I I VI (e.g. CuAgSe) I II V (e.g. AgMgAs) I III IV (e.g. LiAlSi) and II II IV (e.g. CaZnSn) First principles thermodynamics is used to sort the lowestenergy structure and the thermodynamic stability of the 488 unreported hypothetical ABX compounds, many of which were previously proposed to be useful technologically. It is found that as many as 235 of the 488 are unstable with respect to decomposition (hence, are unlikely to be viable technologically) whereas other 235 of the unreported compounds are predicted to be thermodynamically stable (hence, potentially interesting new materials) 18 additional materials are too close to determine. The electronic structures of these predicted stable compounds are evaluated, seeking potential new material functionalities.", "author_names": [ "Xiuwen Zhang", "Liping Yu", "Andriy Zakutayev", "Alex Zunger" ], "corpus_id": 96617850, "doc_id": "96617850", "n_citations": 84, "n_key_citations": 0, "score": 0, "title": "Sorting Stable versus Unstable Hypothetical Compounds: The Case of Multi Functional ABX Half Heusler Filled Tetrahedral Structures", "venue": "", "year": 2012 }, { "abstract": "Abstract The study of new semiconducting materials with enhanced structural, electronic, mechanical and optical properties for the advancement of optoelectronic applications has high merits in material science. First principles calculations are carried out based on density functional theory for the semiconducting Li based half Heusler compounds (X Li; Y= Be, Sc; Z As, Sb, Bi, Ge, Si) for three different atomic configurations namely a, b and g phases of C1b crystal structure. It is predicted that a phase is the lowest energy phase for LiBeAs, LiBeSb, LiBeBi and b phase for LiScGe and LiScSi. The computed electronic structure profile reveals the semiconducting behavior for these materials. The calculated elastic constants obey the necessary mechanical stability condition suggesting that all the half Heusler alloys are mechanically stable at ambient condition. Also, The study of the optical properties of these Li based compounds against the incident photon energy radiation illustrates that these materials can be the effective candidates for the optoelectronic devices. These Li based half Heusler alloys could be promising materials to use in optoelectronic and solar cell applications.", "author_names": [ "A Amudhavalli", "R Rajeswarapalanichamy", "K Iyakutti", "Anoop Kumar Kushwaha" ], "corpus_id": 140054261, "doc_id": "140054261", "n_citations": 23, "n_key_citations": 1, "score": 0, "title": "First principles study of structural and optoelectronic properties of Li based half Heusler alloys", "venue": "", "year": 2018 } ]

[ { "abstract": "Although the demand for high power inductive power transfer (IPT) systems is on the rise, implementation of such IPT systems using low cost semiconductor devices has been a challenge. This study presents a new IPT topology that facilitates easy integration of multiple IPT modules, which are made of low cost and freely available semiconductor components, to cater for high power applications. An intermediate circuit, comprising an inductor capacitor inductor resonant network, serves as a contactless interface through which the modules of primary and secondary (pick up) systems can be either series or parallel integrated. Inductor coils of the intermediate circuit and both primary and pick up systems are magnetically coupled to allow for contactless power transfer. The proposed topology is parallel compensated to minimise its var requirement, and both the direction and amount of power flow are controlled by phase and/or magnitude modulation of voltages generated by primary and pick up side converters. Theoretical analysis, together with simulations and experimental evidence of integrating four prototype bi directional IPT systems to cater for 1.8 kW demand, is presented to show that the proposed new IPT topology is suitable for high power applications, and flexible for both bi directional and uni directional contactless power transfer.", "author_names": [ "Udaya K Madawala", "Duleepa J Thrimawithana" ], "corpus_id": 109513204, "doc_id": "109513204", "n_citations": 46, "n_key_citations": 0, "score": 2, "title": "Modular based inductive power transfer system for high power applications", "venue": "", "year": 2012 }, { "abstract": "The inductive power transfer (IPT) technology is gaining more and more attentions due to its convenience and safety. Because of the current limitation of commercial power electronic devices, the modular parallel technology has been adopted in high power IPT applications. The topologies based on the parallel voltage or current sources are proposed in recent researches. However, these topologies do not have the ability of modular switching due to the coupling of the module impedance. When the number of active modules decreases, the device stress of remaining active modules increases, which reduces the reliability of the IPT systems. To solve the problem, this paper proposes a new parallel topology for modular IPT systems. The device stress in active modules remains unchanged when modules are switched off. A 4.8kW IPT system with three modules is built to verify the decoupling characteristic of proposed parallel topology. The experimental result shows good agreement with the theoretical analysis.", "author_names": [ "Hongsheng Hu", "Tao Cai", "Shanxu Duan", "Xiaoming Zhang", "Jintao Niu", "Hao Feng" ], "corpus_id": 208632946, "doc_id": "208632946", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "A Parallel Topology for Modularized IPT Systems", "venue": "2019 IEEE Energy Conversion Congress and Exposition (ECCE)", "year": 2019 }, { "abstract": "Mask aligner lithography is a technology used to transfer patterns with critical dimensions in the micrometer range from below 1 micron for contact printing to a dozen of microns in proximity printing. This technology is widely used in the fabrication of MEMS, micro optical components, and similar fields. Traditionally, the light sources used for mask aligners are high pressure mercury arc lamps, which emit in the UV rang of the spectrum with peaks at 365 nm, 405 nm and 435 nm, respectively the g h and i lines. These lamps suffer from several disadvantages (inefficient, bulky, dangerous) which makes alternatives interesting. In recent years, high power UV LEDs at the same wavelengths appeared on the market, opening the door to new illumination systems for mask aligners. We have developed a modular 250 W LED based illumination system, which can advantageously replace a 1 kW mercury arc lamp illumination. LEDs, arranged in a 7x7 grid array, are placed in the entrance apertures of individual reflectors, which collimate the individual irradiation to an output angle of 10deg. A subsequent fly's eye integrator homogenizes the illumination in the mask plane. It is followed by a Fourier lens, superimposing the individual channels in the mask plane, and a field lens to ensure telecentric illumination. This multisource approach allows the shaping of the source by switching individual illumination channels, determining the illumination angles and the spatial coherence in the mask plane. This concept can be used, for example, to do source mask optimization. Compared to mercury arc lamp illumination, our system is simultaneously more efficient, compact, versatile, economic and sustainable. In our contribution, we present the design of the system as well as lithographic test prints done with different illumination patterns.", "author_names": [ "Johana Bernasconi", "Toralf Scharf", "M Groccia", "Raoul Kirner", "Wilfried Noell", "Hans Peter Herzig" ], "corpus_id": 88487105, "doc_id": "88487105", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "High power modular LED based illumination system for lithography applications", "venue": "Optical Engineering Applications", "year": 2018 }, { "abstract": "It's very important to maintain the inverter zero voltage switching(ZVS) for inductive power transfer (IPT) system, especially for those high power applications. The ZVS condition can be obtained via regulating the inverter operating frequency of the IPT system. A modeling method based on the energy amplitude and phase is proposed and corresponding controller is designed to maintain the inverter ZVS condition for IPT. The dynamic model of the ZVS for the half bridge inverter is developed firstly. To facilitate the dynamic performance analysis and controller design, the original time variant model is linearized with small signal method at its operating point, which yields to a 4 order transfer function model. A PI controller which maintains ZVS condition via regulating the inverter operating frequency is designed based on the transfer function. An IPT prototype is built to verify the proposed theory. Experiments show that the controller traces the reference of the ZVS angle within 20 ms under various perturbation, which verifies the correction and effectiveness of the model and controller.", "author_names": [ "Jiangtao Liu", "Qijun Deng", "Wenbin Wang", "Zhifan Li" ], "corpus_id": 203655839, "doc_id": "203655839", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Modeling and Control of Inverter Zero Voltage Switching for Inductive Power Transfer System", "venue": "IEEE Access", "year": 2019 }, { "abstract": "A DESIGN OF INDUCTIVE COUPLING WIRELESS POWER TRANSFER SYSTEM FOR ELECTRIC VEHICLE APPLICATIONS Daida Sarika Reddy Old Dominion University, 2019 Director: Dr. Yucheng Zhang This research focuses on the study of using an inductive coupled Wireless Power Transfer (WPT) system for electric vehicle charging applications in Medium Voltage DC (MVDC) power networks. Implementing WPT in Electric Vehicles (EVs) can provide a convenient alternative charging option, versus static charging in a station that would take hours. Also, it can prevent the potential of electrocution hazards that might occur due to the usage of physical medium like wires in EV charging. Even though inductive coupling has been applied in some applications of WPT, it is still not efficient enough to transfer high power at the kilowatts level due to weak coupling between the transmitter and the receiver. Using optimally specified resonant circuits along with inductive coupling can enhance the coupling and make the system more efficient for practical applications. This research aims to design and analyze the performance of a 5 KW WPT circuit. The optimal specification of a resonant circuit is studied and discussed. Theoretical calculations are performed to find the component values in the circuit to reach. The WPT system is firstly verified by performing simulation tests in the MATLAB/SIMULINK environment and then on a low power hardware testbed.", "author_names": [ "Sarika Reddy Daida" ], "corpus_id": 203149772, "doc_id": "203149772", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A Design of Inductive Coupling Wireless Power Transfer System for Electric Vehicle Applications", "venue": "", "year": 2019 }, { "abstract": "This paper proposes to use the double sided LC compensation circuit to realize the long distance and high power capacitive power transfer. The targeted transfer distance is 150mm for the vehicle charging application, resulting in a loosely coupled system. The circuit working principle and the transfer efficiency are provided, which indicates the duality with the conventional series series compensated inductive power transfer system. Using the same capacitive coupler, two load conditions (the constant resistive load and the constant voltage load)are analyzed for the practical applications. The analysis of the CPT system provides the guideline to design and optimize the LC compensated system. The experimental results show that kW level power transfer can be achieved through 150mm distance with dc dc efficiency from the dc source to the dc load to be around 88%", "author_names": [ "Hua Zhang", "Chong Zhu", "Fei Lu" ], "corpus_id": 199508814, "doc_id": "199508814", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Long Distance and High Power Capacitive Power Transfer based on the Double Sided LC Compensation: Analysis and Design", "venue": "2019 IEEE Transportation Electrification Conference and Expo (ITEC)", "year": 2019 }, { "abstract": "This study proposed a hybrid inductive and capacitive wireless power transfer system to achieve high power transfer by combining inductive power transfer (IPT) and capacitive power transfer (CPT) A traditional IPT system imposes a high voltage on the transmitter because of resonance. Meanwhile, high voltages are required to establish an electric field to deliver power to the CPT system. Therefore, they can be combined to a hybrid system to achieve high power transfer by utilising two power transfer paths. A general model of the hybrid IPT and CPT coupler is analysed in detail. With a series series compensation topology, 1.1 kW hybrid system with equal power transferred by two paths is simulated and set up to evaluate the performance of the proposed method. An experimental prototype is built under various conditions, and the result shows that the hybrid system achieved 1.1 kW output power through both of magnetic path and of electric path successfully with 91.9% DC DC efficiency.", "author_names": [ "Bo Luo", "Tao Long", "Ruikun Mai", "Ruimin Dai", "Zhengyou He", "Weihua Li" ], "corpus_id": 116747695, "doc_id": "116747695", "n_citations": 16, "n_key_citations": 1, "score": 0, "title": "Analysis and design of hybrid inductive and capacitive wireless power transfer for high power applications", "venue": "", "year": 2018 }, { "abstract": "One of the most promising inductive power transfer applications is the wireless power supply for locomotives which may cancel the need for pantographs. In order to meet the dynamic and high power demands of wireless power supplies for locomotives, a relatively long transmitter track and multiple receivers are usually adopted. However, during the dynamic charging, the mutual inductances between the transmitter and receivers vary and the load of the locomotives also changes randomly, which dramatically affects the system efficiency. A maximum efficiency point tracking control scheme is proposed to improve the system efficiency against the variation of the load and the mutual inductances between the transmitter and receivers while considering the cross coupling between receivers. Firstly, a detailed theoretical analysis on dual receivers is carried out. Then a control scheme with three control loops is proposed to regulate the receiver currents to be the same, to regulate the output voltage and to search for the maximum efficiency point. Finally, a 2 kW prototype is established to validate the performance of the proposed method. The overall system efficiency (DC DC efficiency) reaches 90.6% at rated power and is improved by 5.8% with the proposed method under light load compared with the traditional constant output voltage control method.", "author_names": [ "Ruikun Mai", "M C Linsen", "Yeran Liu", "Pengfei Yue", "Guangzhong Cao", "Zhengyou He" ], "corpus_id": 30416278, "doc_id": "30416278", "n_citations": 13, "n_key_citations": 1, "score": 0, "title": "A Maximum Efficiency Point Tracking Control Scheme Based on Different Cross Coupling of Dual Receiver Inductive Power Transfer System", "venue": "", "year": 2017 }, { "abstract": "High power >50W) and high efficiency >90% wireless power transfer (WPT) systems are becoming in demand for portable electronic applications. In Fig. 8.2.1, power efficiency and/or output power specifications in prior art designs are much below the expected requirements [1 5] Frequency tuning in [1,2] is simple, but the switching frequency (fSW) deviates from 6.78MHz. Capacitor tuning [3,5] is the most intuitive approach, but the capacitor matrix occupies a large area, and the dynamically tuned compensation capacitor bank is limited by the digital control resolution and compensation accuracy. In addition, the duty cycle control in [4] leads to an unregulated output voltage at the RX side. Existing impedance matching techniques for reducing power loss are not applicable to high power impedance matching of a GaN based WPT system in the case of timevariable charging distance, loading, operation voltage, and temperature variations that induce a wide range of inductive or capacitive loading effects. Inductive loading degrades the efficiency by 51% in a GaN power switch and induces serious coupling effects to the gate of the GaN device due to the hard switching (HS) power loss. Likewise, capacitive loading results in the efficiency degradation of 14% due to the body diode conduction (BDC) power loss. Such large dissipation easily breakdowns a GaN device and even seriously damages the wPt system, especially when transmitting high power. Therefore, simultaneously achieving both (1) the minimized HS and BDC power loss by efficient impedance matching and (2) highly reliable operation of a GaN device over a wide range of loading effects is in urgent demand for high power and high efficiency WPT systems.", "author_names": [ "Che-Hao Yeh", "Yen-Ting Lin", "Chun-Chieh Kuo", "Chao-Jen Huang", "Cheng-Yu Xie", "Shenting Lu", "Wen-Hau Yang", "Ke-Horng Chen", "Kuo-Chi Liu", "Ying-Hsi Lin" ], "corpus_id": 3856091, "doc_id": "3856091", "n_citations": 7, "n_key_citations": 1, "score": 0, "title": "A 70W and 90% GaN based class E wireless power transfer system with automatic matching point search control for zero voltage switching and zero voltage derivative switching", "venue": "2018 IEEE International Solid State Circuits Conference (ISSCC)", "year": 2018 }, { "abstract": "A multi transmitter configuration made by an array of passive resonant elements placed in the proximity of the driver coil for inductive Wireless Power Transfer applications is presented. The array is able to significantly decrease the electric field level produced by the fed loop at the operative frequency of 6 MHz, thus reducing the potentially dangerous radiation over biological tissues (i.e. the Specific Absorption Rate, SAR) Nonetheless, the proposed arrangement preserves the same efficiency level of the simple driver receiver system and it does not affect the useful working distance. Electromagnetic simulations have been performed to evaluate the SAR reduction and the efficiency levels achieved by the multi transmitter configuration in comparison with the driver receiver system. The proposed solution can be extremely useful in all the WPT applications in which the SAR exposure is a concern, such as automotive applications, biomedical implants and rechargeable devices.", "author_names": [ "Danilo Brizi", "Nunzia Fontana", "Sami Barmada", "Agostino Monorchio" ], "corpus_id": 155107258, "doc_id": "155107258", "n_citations": 5, "n_key_citations": 1, "score": 0, "title": "A Multi Transmitter Configuration for High Safety Wireless Power Transfer Applications", "venue": "2019 International Applied Computational Electromagnetics Society Symposium (ACES)", "year": 2019 } ]

[ { "abstract": "Summary form only given. Conventional photodetectors are mostly propelled by p n junctions, where the detection wavelength is constrained by the bandgap of semiconductor material. Recently, a meta linsulator metal (MIM) configuration is demonstrated to be a promising candidate for the next generation photodetection due to its highly tunable operation wavelength, simple configuration, and possibly low cost. The MIM photodetector is operated under the principle of the hot carriers, which can be excited in the metal layer by the incident photons, and collected by the MIM junction to form measurable electrical current. For hot electron photodetection, a high and unidirectional photocurrent is strongly desired. This reveals that the total absorption of the entire system is not an ultimate target; nevertheless, a strong and asymmetrical absorption is desired eventually. However, the existing systems can hardly fulfill this stringent requirement since the incident light couples strongly with both metallic layers as well. To satisfy the inherent demands for the hot carrier photodetection, we have proposed a series of novel configurations such as coaxial Ag/ZnO/Ag nanowires, conformal grating structures, and planar multilayer cavities. Via the finite element electromagnetic simulation and the probability based analytical carrier transport calculation, we explore in detail the optical response and the electrical transport in the devices. Results show that the proposed devices can be designed flexibly and the optimized configurations exhibit superior optical and electrical performance, yielding a strong asymmetrical photoabsorption and a high unidirectional photocurrent. For instance, by asymmetrically aligning the semiconductor barrier relative to the Fermi level of metals and strongly localizing the light energy through plasmonic resonances, the conformal grating system can achieve a strong and highly asymmetrical optical absorption (top metal absorption 99% and a three fold photoresponsivity compared with the conventional grating design; by forming a planar perfect absorber at the targeted wavelength, coaxial nanowire schemes acquire a strong optical absorption and satisfy well the inherent requirement of efficient electron collection, which is predicted to be with an unbiased responsivity of 200 nA/mW.", "author_names": [ "Yaohui Zhan", "Cheng Zhang", "Kai Wu", "Xiaofeng Li" ], "corpus_id": 13507911, "doc_id": "13507911", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Optoelectronic design on the hot carrier photodetectors", "venue": "2016 Progress in Electromagnetic Research Symposium (PIERS)", "year": 2016 }, { "abstract": "Abstract This article presents the characteristics of a relatively new device, the quantum dot infrared (IR) photodetector, or QDIP. Recent advances in the epitaxial growth of strained heterostructures, such as Ga(In)As on GaAs, have led to the realization of coherent islands through the process of self organization. These islands behave electronically as quantum boxes, or quantum dots. The first quantum dot laser was demonstrated almost a decade ago and since then other electronic and optoelectronic devices have been reported. Theoretical and experimental studies of scattering processes and hot carrier dynamics in the quantum dots indicate that the intersubband relaxation rate of the electrons are small and may even exhibit a phonon bottleneck, under weak excitation conditions. This property, together with the three dimensional (3 D) carrier confinement and the near discrete nature of the bound states, is ideal for the design of l o n g w a v e l e n g t h intersubband detectors. Another advantage is the possibility of normal incidence operation due to the selection rules. The QDIP, therefore, has the potential of being a serious contender for applications in high temperature IR detection, and significant progress has been made since its first demonstration nearly five years ago. The properties of these fascinating and important devices are described here. Some comparisons, in terms of dark current, are made with HgCdTe detectors and quantum well IR photodetectors (QWIPs) two other successful technologies for IR detection.", "author_names": [ "Sanjay Krishna", "Adrienne D Stiff-Roberts", "Jamie D Phillips", "Pallab K Bhattacharya", "Stephen W Kennerly" ], "corpus_id": 118480103, "doc_id": "118480103", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Hot Dot Detectors. Infrared Quantum Dot Intersubband Photodetectors Are a Promising Technology for Multiwavelength IR Detection", "venue": "", "year": 2002 }, { "abstract": "Optoelectronic functionalities of photodection and light harnessing rely on the band to band excitation of semiconductors, thus the spectral response of the devices is dictated and limited by their bandgap. A novel approach, free from this restriction, is to harvest the energetic electrons generated by the relaxation of a plasmonic resonance in the vicinity of a metal semiconductor junction. In this configuration, the optoelectronic and spectral response of the detectors can be designed ad hoc just by tailoring the topology of metal structures, which has tremendous applications in solar energy harvesting and photodetection. Fully exploiting hot electron based optoelectronics yet requires a platform that combines their exotic spectral capabilities with large scale manufacturing and high performance. Herein we report the first implementation of a large area, low cost quasi 3D plasmonic crystal (PC) for hot electron photodetection, showcasing multiband selectivity in the VIS NIR and unprecedented responsivity of 70 mA/W.", "author_names": [ "F de Arquer", "Agustin Mihi", "Gerasimos Konstantatos" ], "corpus_id": 118591648, "doc_id": "118591648", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Multiband Tunable Large Area Hot Carrier Plasmonic Crystal Photodetectors", "venue": "", "year": 2014 }, { "abstract": "Based on Photo thermoelectric effect, by illuminating the active area of graphene based optoelectronic devices, strong electron electron interactions of the photo excited carriers along with inherit inefficiency of electron lattice energy relaxation in graphene, results in a sustained population of hot carriers. Furthermore, according to this effect, using generated hot carrier temperature profile and thermoelectric power(S)coefficient, produce a net photo thermoelectric current via the thermoelectric effect. The weakness point of this scenario is optical absorption of graphene. A promising solution to overcome this problem is using plasmonic nanostructures. Here, we show that by using a series of periodic plasmonic grating on top of electrodes, a considerable tunable asymmetry hot carrier profile on the graphene channel can be created. It is shown that by precise design of grating there would be a strong field distribution along one side of graphene sheet, which leads to an increased efficiency and responsivity of graphene based photodetector. The calculated photo thermoelectric current (ITEP shows 6 fold pattern which is qualitatively similar to photo thermoelectric patterns in experimental results.", "author_names": [ "Seyyed Asad Amirhosseini", "Mohammad Karimi", "Reza Safian" ], "corpus_id": 9524094, "doc_id": "9524094", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Hot carrier assisted Photo thermoelectric current using nano plasmonic structures in GFET", "venue": "2016 Fourth International Conference on Millimeter Wave and Terahertz Technologies (MMWaTT)", "year": 2016 }, { "abstract": "Among plasmonic metals, copper (Cu) has great potential for realizing optoelectronic and photoelectrochemical hot carrier devices, owing to its CMOS compatibility and catalytic ability for electrochemical carbon dioxide reduction. Yet, copper hot carrier dynamics have received little attention and the fundamental properties of photoexcited carriers in copper are not well understood. Here, we first demonstrate that Cu nanoantennas on p type gallium nitride (p GaN) enable hot hole driven photodetection across the visible spectrum. By combining experimental internal quantum efficiency (IQE) results with ab initio theoretical modelling, we clarify the competing roles of hot carrier energy and mean free path on the performance of hot hole devices above and below the copper interband absorption threshold. By comparing Cu/p GaN hot hole and Cu/n GaN hot electron photodetectors with the same metal/semiconductor interface (Cu/GaN) we elucidate the transport characteristics of these complementary systems. In particular, we conclude that harnessing hot holes is an attractive strategy for photodetectors operating in the visible and ultraviolet regime. We anticipate that these insights about carrier transport will have a broad impact on the design of hot carrier optoelectronic devices and plasmonic photocatalysts.", "author_names": [ "Giulia Tagliabue", "Joseph S DuChene", "Adela Habib", "Ravishankar Sundararaman", "Harry A Atwater" ], "corpus_id": 215774030, "doc_id": "215774030", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Hot Hole versus Hot Electron Transport at Copper/GaN Heterojunction Interfaces.", "venue": "ACS nano", "year": 2020 }, { "abstract": "Among all plasmonic metals, copper (Cu) has the greatest potential for realizing optoelectronic and photochemical hot carrier devices, thanks to its CMOS compatibility and outstanding catalytic properties. Yet, relative to gold (Au) or silver (Ag) Cu has rarely been studied and the fundamental properties of its photoexcited hot carriers are not well understood. Here, we demonstrate that Cu nanoantennas on p type gallium nitride (p GaN) enable hot hole driven photodetection across the visible spectrum. Importantly, we combine experimental measurements of the internal quantum efficiency (IQE) with ab initio theoretical modeling to clarify the competing roles of hot carrier energy and mean free path on the performance of hot hole devices above and below the interband threshold of the metal. We also examine Cu based plasmonic photodetectors on corresponding n type GaN substrates that operate via the collection of hot electrons. By comparing hot hole and hot electron photodetectors that employ the same metal/semiconductor interface (Cu/GaN) we further elucidate the relative advantages and limitations of these complementary plasmonic systems. In particular, we find that harnessing hot holes with p type semiconductors is a promising strategy for plasmon driven photodetection across the visible and ultraviolet regimes. Given the technological relevance of Cu and the fundamental insights provided by our combined experimental and theoretical approach, we anticipate that our studies will have a broad impact on the design of hot carrier optoelectronic devices and plasmon driven photocatalytic systems.", "author_names": [ "Giulia Tagliabue", "Joseph S DuChene", "Adela Habib", "Ravishankar Sundararaman", "Harry A Atwater" ], "corpus_id": 219863419, "doc_id": "219863419", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Hot Hole versus Hot Electron Transport at Cu/ GaN Heterojunction Interfaces", "venue": "", "year": 2020 }, { "abstract": "Neuromorphic computing overcomes limitations of traditional von Neumann computing architectures by incorporating synaptic interconnections of neurons with nonlinear activation functions in a distributed neural network architecture. While some electronic neuromorphic computing demonstrations have shown significant energy efficiency improvements over their von Neumann counterparts, their scalability and throughput are still limited due to the impedance of the electrical wire interconnects. Photonic spiking neural networks (PSNNs) overcome the limitations of the electrical interconnects and potentially offer exceptionally high throughput and energy efficiency compared to electronic neuromorphic counterparts while maintaining their benefits from event driven computing capability. In this paper, we designed, prototyped, and experimentally demonstrated, for the first time to our knowledge, an optoelectronic spiking neuron inspired by the Izhikevich model incorporating both excitatory and inhibitory optical spiking inputs and producing optical spiking outputs accordingly. The optoelectronic neurons consist of three transistors acting as electrical spiking circuits, a vertical cavity surface emitting laser (VCSEL) for optical spiking outputs, and two photodetectors for excitatory and inhibitory optical spiking inputs. Additional inclusion of capacitors and resistors complete the Izhikevich inspired optoelectronic neurons, which receive excitatory and inhibitory optical spikes as inputs from other optoelectronic neurons. We developed a detailed optoelectronic neuron model in Verilog A and simulated the circuit level operation of various cases with excitatory input and inhibitory input signals. The experimental results closely resemble the simulated results and demonstrate how the excitatory inputs trigger the optical spiking outputs while the inhibitory inputs suppress the outputs. Utilizing the simulated neuron model, we conducted simulations using fully connected (FC) and convolutional neural networks (CNN) The simulation results using MNIST handwritten digits recognition show 90% accuracy on unsupervised learning and 97% accuracy on a supervised modified FC neural network. We further designed a nanoscale optoelectronic neuron utilizing quantum impedance conversion where a 200 aJ/spike input can trigger the output from on chip nanolasers with 10 fJ/spike. The nanoscale neuron can support a fanout of ~80 or overcome 19 dB excess optical loss while running at 10 GSpikes/second in the neural network, which corresponds to 100 throughput and 1000 energy efficiency improvement compared to stateof art electrical neuromorphic hardware such as Loihi and NeuroGrid. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement", "author_names": [ "Yun-jhu Lee", "Mehmet Berkay On", "Xian Xiao", "Roberto Proietti", "S J Ben Yoo" ], "corpus_id": 233864372, "doc_id": "233864372", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Izhikevich Inspired Optoelectronic Neurons with Excitatory and Inhibitory Inputs for Energy Efficient Photonic Spiking Neural Networks", "venue": "ArXiv", "year": 2021 }, { "abstract": "The ability to detect light over a broad spectral range is central to several technological applications in imaging, sensing, spectroscopy and communication. Graphene is a promising candidate material for ultra broadband photodetectors, as its absorption spectrum covers the entire ultraviolet to far infrared range. However, the responsivity of graphene based photodetectors has so far been limited to tens of mA W( 1) (refs 5 10) due to the small optical absorption of a monolayer of carbon atoms. Integration of colloidal quantum dots in the light absorption layer can improve the responsivity of graphene photodetectors to 1 x 10(7) A W( 1) (ref. 11) but the spectral range of photodetection is reduced because light absorption occurs in the quantum dots. Here, we report an ultra broadband photodetector design based on a graphene double layer heterostructure. The detector is a phototransistor consisting of a pair of stacked graphene monolayers (top layer, gate; bottom layer, channel) separated by a thin tunnel barrier. Under optical illumination, photoexcited hot carriers generated in the top layer tunnel into the bottom layer, leading to a charge build up on the gate and a strong photogating effect on the channel conductance. The devices demonstrated room temperature photodetection from the visible to the mid infrared range, with mid infrared responsivity higher than 1 A W( 1) as required by most applications. These results address key challenges for broadband infrared detectors, and are promising for the development of graphene based hot carrier optoelectronic applications.", "author_names": [ "Chang-Hua Liu", "You-Chia Chang", "Theodore B Norris", "Zhaohui Zhong" ], "corpus_id": 12004569, "doc_id": "12004569", "n_citations": 773, "n_key_citations": 8, "score": 0, "title": "Graphene photodetectors with ultra broadband and high responsivity at room temperature.", "venue": "Nature nanotechnology", "year": 2014 }, { "abstract": "Abstract Embedding plasmonic metal nanostructures into the semiconductor materials offers a new route to enhance the performance of photodetectors. Herein, we have reported the development of a high performance broadband photodetector based on a new core shell nanostructure, termed Ag@PbS, where Ag nanoparticle cores were synthesized by DC sputtering technique and subsequently coated by PbS shell using a convenient wet chemical method. Transmission electron microscopy, energy dispersive X ray spectroscopy, and X ray diffraction analyses provide clear evidence of core shell heterostructure formation. Close interfacial contact and Schottky barrier formation efficiently boost separation and transfer of photogenerated charge carriers across the interface of the core and shell. Moreover, the presence of Ag cores promotes photodetecting performance through the strong light absorption and scattering, abundant hot hole carriers injection and plasmonic energy transfer. Therefore, the photoconductive device delivered a broadband response range from visible to near infrared with a maximum responsivity of 26.1 A W 1, a specific detectivity of 1.8 x 1013 Jones and EQE of 4013% under 808 nm laser illumination at low light intensity 0.14 mW cm 2) Importantly, the device exhibits a fast response time of 170 ms along with excellent operational reliability and long term stability in the ambient air atmosphere. Such a result sheds new light on the design and development of novel core shell nanostructures with advanced optoelectronic properties.", "author_names": [ "Masoud Mozafari", "Sh Nasresfahani", "Moheb Sheikhi", "H Agharezaei" ], "corpus_id": 224916433, "doc_id": "224916433", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "An enhanced Vis NIR photodetector based on Ag@ PbS core shell plasmonic heterostructure", "venue": "", "year": 2021 }, { "abstract": "Abstract The rapid progress in the field of organic inorganic halide perovskite (OIHP) has led to not only >24% power conversion efficiency for photovoltaics, but also provided breakthroughs in processing of materials with tailored functional behavior. This ability to design and synthesize engineered OIHP materials has opened the possibility to develop various other optoelectronic applications. In addition to that of photovoltaics, this includes photodetector, laser, light emitting diode, X ray and gamma detector, photocatalyst, memory, transducer, transistor, and more. At this stage, the emphasis is on fundamental understanding of the underlying physics and chemistry of OIHP materials, which will assist the evaluation of device performance and provide explanations for some of the contradictory results reported in literature. This review discusses the theoretical and experimental analysis of the OIHP materials reported from various sources and considers the chemical and structural origin of their unique optoelectronic properties, correlated microstructures, and newly discovered extraordinary properties. In the first few sections, we summarize and discuss the crystallography, chemical bonding, and substitutional effects, followed by the discussion of correlated photophysics including the optical, electronic, excitonic, charge transport, and ion migration characteristics. Next, we revisit and discuss the in depth behavior of films with unique defect structure, structural disorder, morphology, and crystallization thermodynamics. Novel thermal electrical optical properties including ferroelectricity, hot carrier contribution, spin orbit coupling effect, terahertz time response, edge state discovery, etc. are rationalized considering the results debated in the community. We elaborate on the opportunities and challenges regarding stability, toxicity, and hysteresis. The viewpoint on commercialization of OIHP based solar module is presented with the goal of identifying near term opportunities. Throughout this review, the overarching goal is to provide a simplified explanation for the complex physical effects and mechanisms, underlying interconnections between different mechanisms, uncertainties reported in literature, and recent important theoretical and experimental discoveries.", "author_names": [ "Kai Wang", "Dong Yang", "Congcong Wu", "Mohan Sanghadasa", "Shashank Priya" ], "corpus_id": 199188636, "doc_id": "199188636", "n_citations": 44, "n_key_citations": 0, "score": 0, "title": "Recent progress in fundamental understanding of halide perovskite semiconductors", "venue": "", "year": 2019 } ]

[ { "abstract": "With the global trend to produce clean electrical energy, the penetration of renewable energy sources in existing electricity infrastructure is expected to increase significantly within the next few years. The solid state transformer (SST) is expected to play an essential role in future smart grid topologies. Unlike traditional magnetic transformer, SST is flexible enough to be of modular construction, enabling bi directional power flow and can be employed for AC and DC grids. Moreover, SSTs can control the voltage level and modulate both active and reactive power at the point of common coupling without the need to external flexible AC transmission system device as per the current practice in conventional electricity grids. The rapid advancement in power semiconductors switching speed and power handling capacity will soon allow for the commercialisation of grid rated SSTs. This paper is aimed at introducing a state of the art review for SST proposed topologies, controllers, and applications. Additionally, strengths, weaknesses, opportunities, and threats (SWOT) analysis along with a brief review of market drivers for prospective commercialisation are elaborated.", "author_names": [ "Ahmed Abu-Siada", "Jad Budiri", "A F Abdou" ], "corpus_id": 116129019, "doc_id": "116129019", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Solid State Transformers Topologies, Controllers, and Applications: State of the Art Literature Review", "venue": "", "year": 2018 }, { "abstract": "The high voltage power transformer is the critical element of the power system, which requires continuous monitoring to prevent sudden catastrophic failures and to ensure an uninterrupted power supply. The most common failures in the transformer are due to partial discharge (PD) in electrical insulations which are the results of the insulation degradation over time. Different approaches have been proposed to monitor, detect, and locate the partial discharge in power transformers. This paper reviews and evaluates the current state of the art methods for PD detection and localization techniques, and methodologies in power transformers. Detailed comparisons of PD detection techniques have been identified and discussed in this paper. The drawbacks and challenges of different partial discharge measurement techniques have been elaborated. Finally, brief reviews of PD denoising signals, feature extraction of PD signals, and classification of partial discharge sources have been addressed.", "author_names": [ "Md Rashid Hussain", "Shady S Refaat", "Haitham Abu-Rub" ], "corpus_id": 233465574, "doc_id": "233465574", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Overview and Partial Discharge Analysis of Power Transformers: A Literature Review", "venue": "IEEE Access", "year": 2021 }, { "abstract": "Due to the large number of distribution transformers in the distribution grid, the status of distribution transformers plays an important role in ensuring the safe and reliable operation of the these grids. To evaluate the distribution transformer health, many assessment techniques have been studied and developed. These tools will support the transformer operators in predicting the status of the distribution transformer and responding effectively. This paper will review the literature in the area, analyze the latest techniques as well as highlight the advantages and disadvantages of current methodologies.", "author_names": [ "Q T T Tran", "Kevin Davies", "Leon R Roose", "Puthawat Wiriyakitikun", "Jaktupong Janjampop", "Eleonora Riva Sanseverino", "Gaetano Zizzo" ], "corpus_id": 228913302, "doc_id": "228913302", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "A Review of Health Assessment Techniques for Distribution Transformers in Smart Distribution Grids", "venue": "", "year": 2020 }, { "abstract": "One of the most important innovation expectation in railway electrical equipment is the replacement of the on board transformer with a high power converter. Since the transformer operates at line frequency (i.e. 50 Hz or 16 2/3 Hz) it represents a critical component from weight point of view and, moreover, it is characterized by quite poor efficiency. High power converters for this application are characterized by a medium frequency inductive coupling and are commonly referred as Power Electronic Transformers (PET) Medium Frequency Topologies or Solid State Transformers (SST) Many studies were carried out and various prototypes were realized until now, however, the realization of such a system has some difficulties, mainly related to the high input voltage (i.e. 25 kV for 50 Hz lines and 15 kV for 16 2/3 Hz lines) and the limited performance of available power electronic switches. The aim of this study is to present a survey on the main solutions proposed in the technical literature and, analyzing pros and cons of these studies, to introduce new possible circuit topologies for this application.", "author_names": [ "Stefano Farnesi", "Mario Marchesoni", "Massimiliano Passalacqua", "Luis Vaccaro" ], "corpus_id": 211105412, "doc_id": "211105412", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Solid State Transformers in Locomotives Fed through AC Lines: A Review and Future Developments", "venue": "", "year": 2019 }, { "abstract": "It is well known that transmission and distribution sections of a real world power system are physically coupled by distribution transformers. This implies that almost every large scale power system is an integrated Transmission Distribution (T D) system that consists of a Transmission Power Subsystem (TPS) and multiple Distribution Power Subsystems (DPSs) Therefore, technically, only by considering the TPS and the DPS as a whole, can people accurately assess the state of the entire power system and optimally control the system.", "author_names": [ "Zhengshuo Li" ], "corpus_id": 67475043, "doc_id": "67475043", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Backgrounds and Literature Review", "venue": "", "year": 2018 }, { "abstract": "This paper presents a literature review on magnetically controlled devices, variable inductors (VI) and variable transformers (VT) and their applications to lighting gears for discharge lamps and/or LED lamps. These current controlled devices are mainly characterized by nonlinear and non uniform saturation of the magnetic core. The paper describes the fundamentals and basic operating principle of such devices and provides an overview of existing patents. These patents refer the devices, VIs or VTs, as useful or industrially applicable. Some present one or more claims regarding the construction of the device and behavioral characteristic; others refer to specific applications, such as voltage regulation or universal ballast operation. Afterwards, the paper focuses on the review of specific techniques and circuits taking advantage of the presence of a controlled inductance value, by covering recent applications regarding discharge and solid state lamp drivers. These applications will show how these multi winding devices, typically not considered due to their low efficiency, may fulfill an important role and add features to state of the art lamp drivers.", "author_names": [ "Marina S Perdigao", "Maikel Fernando Menke", "Alysson Raniere Seidel", "Rafael A Pinto", "Jose Marcos Alonso Alvarez" ], "corpus_id": 16155091, "doc_id": "16155091", "n_citations": 42, "n_key_citations": 4, "score": 0, "title": "A Review on Variable Inductors and Variable Transformers: Applications to Lighting Drivers", "venue": "IEEE Transactions on Industry Applications", "year": 2016 }, { "abstract": "Transformers have achieved great success in many artificial intelligence fields, such as natural language processing, computer vision, and audio processing. Therefore, it is natural to attract lots of interest from academic and industry researchers. Up to the present, a great variety of Transformer variants (a.k.a. X formers) have been proposed, however, a systematic and comprehensive literature review on these Transformer variants is still missing. In this survey, we provide a comprehensive review of various X formers. We first briefly introduce the vanilla Transformer and then propose a new taxonomy of X formers. Next, we introduce the various X formers from three perspectives: architectural modification, pre training, and applications. Finally, we outline some potential directions for future research.", "author_names": [ "Tianyang Lin", "Yuxin Wang", "Xipeng Qiu" ], "corpus_id": 235368340, "doc_id": "235368340", "n_citations": 11, "n_key_citations": 1, "score": 1, "title": "A Survey of Transformers", "venue": "ArXiv", "year": 2021 }, { "abstract": "In data analysis, context information plays a significant role in enhancing the quality of the insight obtained. Furthermore, spatial analysis helps understand spatial relationships among entities. Nevertheless, findings of a comprehensive literature review show that the characterization of geographic areas based on user generated content, such as text messages, has not been sufficiently explored. This paper focuses on investigating how to combine and exploit geographic information with user generated text content to detect geographic clusters of textual events, and infer relationships between each cluster and a fixed set of retail product categories, which we consider as an insightful way to perform spatial market segmentation. We propose a workflow composed of several machine learning models incorporating Transformers as an attention mechanism and BERT based data augmentation capable of predicting product classes from Amazon product reviews and Twitter message corpora, and then characterizing the obtained geographic clusters based on their aggregated scores. The output of our system is an effective visualization of the geographic areas with their corresponding relevance score against a fixed set of categories. We trained a product document classifier achieving an F1 Score of 86% in the test set for product reviews, and of 76% in the test set for tweets; and validated our approach by manually annotating a subset of Twitter data with respect to ten product categories. Our approach provides practitioners with a mechanism to combine location context, a Transformer encoder, and transfer learning to derive insights from geo spatial and text data; and researchers with opportunities to continue advancing the field.", "author_names": [ "Luis E Ferro-Diez", "Norha M Villegas", "Javier Diaz-cely", "Sebastian G Acosta" ], "corpus_id": 233263234, "doc_id": "233263234", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Geo Spatial Market Segmentation Characterization Exploiting User Generated Text Through Transformers Density Based Clustering", "venue": "IEEE Access", "year": 2021 }, { "abstract": "In this project dynamic thermal rating for transformers and its effect on transformer reliability are investigated. A literature review is done on different thermal models used for this purpose and", "author_names": [ "Tahere Zarei" ], "corpus_id": 204090213, "doc_id": "204090213", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Analysis of reliability improvements of transformers after application of dynamic rating", "venue": "", "year": 2017 }, { "abstract": "In multi phase power conversion circuits, achieving an equalized current sharing between the paralleled modules is a challenge. Especially, in the LLC resonant converter topology, where the voltage gain is very sensitive to a minor change in the resonant tank parameters. In practical applications, the resonant tank parameters are never exactly identical among the phases, leading to unbalanced current sharing between the paralleled modules. This paper reviews the state of the art of current balance mechanisms proposed previously in the literature and revisits a newly proposed method to improve the current balance, which relies on a single balancing transformer connected in series with the paralleled resonant tanks. A comparison between the proposed method and connecting the three transformers in star is conducted. While evaluating the current balancing methods, the following sources of unbalance have been considered: a) resonant and magnetizing inductances b) resonant capacitors. c) on resistances of the switching devices. d) propagation delay of the gate drivers.", "author_names": [ "Mostafa Noah", "Jun Imaoka", "Yuki Ishikura", "Kazuhiro Umetani", "Masayoshi Yamamoto" ], "corpus_id": 52001645, "doc_id": "52001645", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Review of Current Balance Mechanism in Multiphase LLC Resonant Converters", "venue": "2018 IEEE 27th International Symposium on Industrial Electronics (ISIE)", "year": 2018 } ]

[ { "abstract": "Preface to Third Edition. 1 Resistivity. 1.1 Introduction. 1.2 Two Point Versus Four Point Probe. 1.3 Wafer Mapping. 1.4 Resistivity Profiling. 1.5 Contactless Methods. 1.6 Conductivity Type. 1.7 Strengths and Weaknesses. Appendix 1.1 Resistivity as a Function of Doping Density. Appendix 1.2 Intrinsic Carrier Density. References. Problems. Review Questions. 2 Carrier and Doping Density. 2.1 Introduction. 2.2 Capacitance Voltage (C V) 2.3 Current Voltage (I V) 2.4 Measurement Errors and Precautions. 2.5 Hall Effect. 2.6 Optical Techniques. 2.7 Secondary Ion Mass Spectrometry (SIMS) 2.8 Rutherford Backscattering (RBS) 2.9 Lateral Profiling. 2.10 Strengths and Weaknesses. Appendix 2.1 Parallel or Series Connection? Appendix 2.2 Circuit Conversion. References. Problems. Review Questions. 3 Contact Resistance and Schottky Barriers. 3.1 Introduction. 3.2 Metal Semiconductor Contacts. 3.3 Contact Resistance. 3.4 Measurement Techniques. 3.5 Schottky Barrier Height. 3.6 Comparison of Methods. 3.7 Strengths and Weaknesses. Appendix 3.1 Effect of Parasitic Resistance. Appendix 3.2 Alloys for Contacts to Semiconductors. References. Problems. Review Questions. 4 Series Resistance, Channel Length and Width, and Threshold Voltage. 4.1 Introduction. 4.2 PN Junction Diodes. 4.3 Schottky Barrier Diodes. 4.4 Solar Cells. 4.5 Bipolar Junction Transistors. 4.6 MOSFETS. 4.7 MESFETS and MODFETS. 4.8 Threshold Voltage. 4.9 Pseudo MOSFET. 4.10 Strengths and Weaknesses. Appendix 4.1 Schottky Diode Current Voltage Equation. References. Problems. Review Questions. 5 Defects. 5.1 Introduction. 5.2 Generation Recombination Statistics. 5.3 Capacitance Measurements. 5.4 Current Measurements. 5.5 Charge Measurements. 5.6 Deep Level Transient Spectroscopy (DLTS) 5.7 Thermally Stimulated Capacitance and Current. 5.8 Positron Annihilation Spectroscopy (PAS) 5.9 Strengths and Weaknesses. Appendix 5.1 Activation Energy and Capture Cross Section. Appendix 5.2 Time Constant Extraction. Appendix 5.3 Si and GaAs Data. References. Problems. Review Questions. 6 Oxide and Interface Trapped Charges, Oxide Thickness. 6.1 Introduction. 6.2 Fixed, Oxide Trapped, and Mobile Oxide Charge. 6.3 Interface Trapped Charge. 6.4 Oxide Thickness. 6.5 Strengths and Weaknesses. Appendix 6.1 Capacitance Measurement Techniques. Appendix 6.2 Effect of Chuck Capacitance and Leakage Current. References. Problems. Review Questions. 7 Carrier Lifetimes. 7.1 Introduction. 7.2 Recombination Lifetime/Surface Recombination Velocity. 7.3 Generation Lifetime/Surface Generation Velocity. 7.4 Recombination Lifetime Optical Measurements. 7.5 Recombination Lifetime Electrical Measurements. 7.6 Generation Lifetime Electrical Measurements. 7.7 Strengths and Weaknesses. Appendix 7.1 Optical Excitation. Appendix 7.2 Electrical Excitation. References. Problems. Review Questions. 8 Mobility. 8.1 Introduction. 8.2 Conductivity Mobility. 8.3 Hall Effect and Mobility. 8.4 Magnetoresistance Mobility. 8.5 Time of Flight Drift Mobility. 8.6 MOSFET Mobility. 8.7 Contactless Mobility. 8.8 Strengths and Weaknesses. Appendix 8.1 Semiconductor Bulk Mobilities. Appendix 8.2 Semiconductor Surface Mobilities. Appendix 8.3 Effect of Channel Frequency Response. Appendix 8.4 Effect of Interface Trapped Charge. References. Problems. Review Questions. 9 Charge based and Probe Characterization. 9.1 Introduction. 9.2 Background. 9.3 Surface Charging. 9.4 The Kelvin Probe. 9.5 Applications. 9.6 Scanning Probe Microscopy (SPM) 9.7 Strengths and Weaknesses. References. Problems. Review Questions. 10 Optical Characterization. 10.1 Introduction. 10.2 Optical Microscopy. 10.3 Ellipsometry. 10.4 Transmission. 10.5 Reflection. 10.6 Light Scattering. 10.7 Modulation Spectroscopy. 10.8 Line Width. 10.9 Photoluminescence (PL) 10.10 Raman Spectroscopy. 10.11 Strengths and Weaknesses. Appendix 10.1 Transmission Equations. Appendix 10.2 Absorption Coefficients and Refractive Indices for Selected Semiconductors. References. Problems. Review Questions. 11 Chemical and Physical Characterization. 11.1 Introduction. 11.2 Electron Beam Techniques. 11.3 Ion Beam Techniques. 11.4 X Ray and Gamma Ray Techniques. 11.5 Strengths and Weaknesses. Appendix 11.1 Selected Features of Some Analytical Techniques. References. Problems. Review Questions. 12 Reliability and Failure Analysis. 12.1 Introduction. 12.2 Failure Times and Acceleration Factors. 12.3 Distribution Functions. 12.4 Reliability Concerns. 12.5 Failure Analysis Characterization Techniques. 12.6 Strengths and Weaknesses. Appendix 12.1 Gate Currents. References. Problems. Review Questions. Appendix 1 List of Symbols. Appendix 2 Abbreviations and Acronyms. Index.", "author_names": [ "Dieter K Schroder" ], "corpus_id": 110493874, "doc_id": "110493874", "n_citations": 6120, "n_key_citations": 383, "score": 1, "title": "Semiconductor Material and Device Characterization", "venue": "", "year": 1990 }, { "abstract": "DESCRIPTION This Third Edition updates a landmark text with the latest findings The Third Edition of the internationally lauded Semiconductor Material and Device Characterization brings the text fully up to date with the latest developments in the field and includes new pedagogical tools to assist readers. Not only does the Third Edition set forth all the latest measurement techniques, but it also examines new interpretations and new applications of existing techniques.", "author_names": [ "Dieter K Schroder" ], "corpus_id": 136551178, "doc_id": "136551178", "n_citations": 474, "n_key_citations": 46, "score": 0, "title": "Semiconductor Material and Device Characterization, 3rd Edition", "venue": "", "year": 2005 }, { "abstract": "", "author_names": [ "Dieter K Schroder" ], "corpus_id": 138410056, "doc_id": "138410056", "n_citations": 488, "n_key_citations": 10, "score": 0, "title": "Semiconductor Material and Device Characterization: Schroder/Semiconductor Material and Device Characterization, Third Edition", "venue": "", "year": 2005 }, { "abstract": "The advent of the new nano scale high speed materials and devices require metrology tools capable of characterization at the operating frequency range with nano scale resolution. The non destructive measurement of dopant profile and carrier concentration in 2D and 3D are critical in the new emerging materials and devices such as carbon nanotubes, graphene, nanowires and spintronics. A new Scanning Microwave Microscope (SMM) has been developed to characterize the material and devices at microwave frequencies with nanometer resolution. The SMM has been shown to be capable of quantitative characterization of metals, semiconductors and dielectrics.", "author_names": [ "Hassan Tanbakuchi", "Ferry Kienberger", "Matt Richter", "Michael Dieudonne", "Manuel Kasper", "Georg Gramse" ], "corpus_id": 15592132, "doc_id": "15592132", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Semiconductor Material and Device Characterization via Scanning Microwave Microscopy", "venue": "2013 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS)", "year": 2013 }, { "abstract": "The potential of using low frequency noise as a diagnostic tool for semiconductor material and device characterization is reviewed. First a brief introduction is given related to the different noise sources in order to obtain insight into the spectral information present in their response signal. Special attention is given to 1/f noise, random telegraph signal noise, and generation recombination noise. The physics associated with the noise properties of bulk and interface defect centers is investigated and illustrated by some case studies for both metal oxide semiconductor and bipolar devices. Advantages and disadvantages compared to other spectroscopic techniques are addressed in view of future trends in electronic devices.", "author_names": [ "Cor Claeys", "Eddy Simoen" ], "corpus_id": 97064794, "doc_id": "97064794", "n_citations": 39, "n_key_citations": 0, "score": 0, "title": "Noise as a Diagnostic Tool for Semiconductor Material and Device Characterization", "venue": "", "year": 1998 }, { "abstract": "Abstract Novel developments in this review relate to mcorona Kelvin, realized by miniaturization of corona charging spot and adaptation of Kelvin Force Microscopy, KFM. Resolution improvement has opened possibilities of non contact characterization of miniature scribe line test sites on processed semiconductor wafers. Surface diffusion of corona ions can be quantified with mcorona KFM leading to the development of the kinetic C V method. The quantified decrease of charge due to diffusion creates a \"charge bias sweep\" Application examples illustrate the determination of dielectric capacitance; flatband voltage; and effective gate metal work function indicators. Applications to SiC demonstrate doping density determination with kinetic CV. Non Visible Defect, NVD, inspection benefits from micro resolution characterization in two ways: 1) defects revealed by whole wafer mapping can now be examined in high resolution; illustrated using an example of Na contamination; and 2) detailed characterization can be performed within small defective areas providing a means for better understanding of a specific NVD.", "author_names": [ "Dmitriy Marinskiy", "Piotr Edelman", "Jacek J Lagowski", "Thye Chong Loy", "Carlos Almeida", "Alexandre Savtchouk" ], "corpus_id": 124661112, "doc_id": "124661112", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Kelvin Force Microscopy and corona charging for semiconductor material and device characterization", "venue": "", "year": 2016 }, { "abstract": "The focus of the present work is addressed to the field of organic electronics, which has attracted increasing interest for the development of flexible, large area and low cost electronic applications, from light emitting diodes to thin film transistors and solar cells. The book describes initially the application of low frequency electronic noise spectroscopy for the characterization of organic electronic devices as an innovative and non destructive technique. The second part is focused on the application of a well known characterization technique, such as the admittance spectroscopy, in order to characterize the conduction and dielectric properties of a test structures based on a new organic materials for future applications in the blue organic light emitting diode and in the quantum dots polymer solar cells.", "author_names": [ "Landi Giovanni" ], "corpus_id": 139586990, "doc_id": "139586990", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Organic semiconductor material and device characterization", "venue": "", "year": 2015 }, { "abstract": "Der Schwerpunkt der vorliegenden Arbeit liegt auf dem Gebiet der organischen Elektronik, welches zunehmendes Interesse fur die Entwicklung von flexiblen, grosflachigen und kostengunstigen elektronischen Anwendungen hat, zum Beispiel fur die Entwicklung von organischen Leuchtdioden, Dunnfilmtransistoren und Solarzellen. Die vorliegende Arbeit beschreibt zunachst, die Anwendung von elektronischer Niederfrequenz Rauschspektroskopie zur Charakterisierung von organischen elektronischen Bauelementen als innovative und zerstorungsfreie Messmethode. Insbesondere die, durch Temperatur Stress bedingte, Modifizierung der elektronischen Transportparameter der nicht beleuchteten Bulk Heterojunction Polymer Solarzelle wird im Detail diskutiert. Bei der untersuchten organischen Solarzelle handelt es sich um eine Solarzelle, in welcher die aktive Schicht aus einer Mischung von Poly (3 hexylthiophen) (P3HT) und [6,6] phenyl C61 buttersaure methylester (PCBM) besteht. Dies ist die klassische Referenzstruktur fur Polymer Solarzellen. Vor der irreversiblen Anderung der aktiven Schicht kann die Solarzelle bei niedrigen Frequenzen als Parallelschaltung zwischen einem zeitlich fluktuirendem Widerstands RX(t) und einer Kapazitat CX modelliert werden. Die unter Gleichvorspannung injizierten Ladungstrager in der aktiven Schicht andern die aquivalente elektrische Impedanz verandert damit auch die Rauschspektren. Die experimentelle Spektralkurve kann mittels eines theoretischen Modells auf der Basis der Kapazitat Cm, die durch die berschuss Minoritatsladungstrager in der aktiven Schicht bestimmt wird, und des Widerstands Rrec interpretiert werden. Das gemessene elektrische Rauschen hat eine 1/f Charakteristik bis zu einer Grenzfrequenz fx. Fur hohere Frequenzen wird eine eine 1/f3 Abhangigkeit beobachtet. Die Analyse des Wertes von fx gibt Informationen uber die Rekombinationslebensdauer der Elektronen in der aktiven Schicht, wahrend die Spannungsabhangigkeit von C Informationen uber die Zustandsdichte fur das niedrigste unbesetzte Molekulorbital (LUMO) im PCBM Material ermoeglicht. Des Weiteren wurde die Niederfrequenz Rauschspektroskopie verwendet, um Anderungen der aktiven Schicht der Polymer Solarzelle durch thermische Belastung zu untersuchen. Die Temperatur wurde als eine der externen Parameter, die die Solarzellendegradation beschleunigen, identifiziert. Die VII Analyse des elektrischen Rauschens bei niedrigen Frequenzen ergibt eine deutliche Abnahme der Ladungstragernullfeldbeweglichkeit wahrend eines Temper Zyklus. Dieser Effekt wurde auf morphologischen Veranderungen der aktiven Schicht der Solarzelle und der Grenzflache zwischen dem Metallkontakt und der aktiven Schicht zuruckgefuhrt. Auserdem wurde der Einflus der Verwendung verschiedener Losungsmittelzusatze wahrend des Filmherstellung auf die elektronischen Transportparameter in den Solarzellen mittels Rausch Spektroskopie untersucht, und durch einen ausfuhrlicher Vergleich der optoelektronischen Eigenschaften von Solarzellen, welche mit verschiedenen Losungsmitteln hergestellt worden sind, erganzt. Einerseits ist eine auf P3HT/PCBM basierende Bulk Heterojunction Solarzelle einer der prominentesten Kandidaten fur eine Polymer Solarzelle, aber auf der anderen Seite, wird ihre Umwandlungseffizienz durch relative niedrige Photonenabsorption im langwelligen Spektralbereich begrenzt. Eine Moglichkeit, den Wirkungsgrad zu erhohen, ist die Absorption in der aktiven Schicht durch Zugabe von Materialien, die Licht im roten und infraroten Spektralbereich absorbieren, zu erhohen. Eine der vielversprechendsten Materialklassen fur diese Aufgabe sind anorganische Quantenpunkte (QD) In der vorliegenden Studie wurden InP/ZnS Quantenpunkte mit einem Emissionswellenlangenmaximum von etwa 660 nm zu diesem Zweck untersucht. Diese wurden mit mehrwandigen Kohlenstoff Nanorohren kombiniert, um die Ladungstragertrennung zu begunstigen und die laterale Leitfahigkeit der organischen Filme zu verbessern. Die Nanoteilchen wurden durch Spin coating zusammen mit einer nicht leitenden Matrix Polymer Losung (PMMA) auf Glas und Silizium Substrate aufgebracht, um die Wechselwirkung zwischen den Quantenpunkten und der Kohlenstoff Nanorohren und deren elektrische Leitfahigkeit unabhangig vom zukunftigen Wirtsmaterial in der Polymer Solarzelle zu untersuchen. Die QDKonzentration wurde dabei konstant gehalten und die Konzentration der CNTs in dem abgeschiedenen Film variiert. Die Charakterisierung der Filmmorphologie durch Rasterelektronenmikroskopie und der optischen Eigenschaften mittels Photolumineszenz und Transmissionsmessungen zeigten ein ziemlich komplexes Zusammenspiel zwischen Nanorohren und Quantenpunkten. Insbesondere wurde eine starke Neigung der Nanorohren festgestellt, sich im Falle hoher Konzentrationen von CNTs in Kugelform anzuordnen. Messungen der elektrischen Leitfahigkeit in Sandwich Konfiguration wurden durchgefuhrt, um den Grad der Zunahme der Leitfahigkeit der Probe durch die Nanorohren zu uberprufen. Im Falle der Messungen VIII in Sandwichkonfiguration, wobei die PMMA/CNT Filme direkt auf einem kristallinen Siliziumsubstrat abgeschieden wurden, zeigte die Bildung einer Art von Schottky Diode mit einer monotone Abnahme der Schwellspannung in Vorwartsrichtung mit zunehmender CNT Konzentration. Daruber hinaus ist die Abnahme der Lichtdurchlassigkeit der leitenden Duennschichten mit steigender CNT Konzentration weniger ausgepragt, wenn Quantenpunkte hinzugegeben wurden. Die optische Durchlassigkeit in einem Wellenlangenbereich zwischen 380 nm und 800 nm der Verbundstoffe aus PMMA und Nanopartikeln konnte empirisch als einfaches Polynom zweiter Ordnung ausgedruckt werden. Im vorletzten Teil der Arbeit, wird die Synthese und die Charakterisierung mittels Struktur und thermischer Analyse, sowie Infrarot Spektroskopie von einer neuen Art von \"kleinen Molekulen\" untersucht. Diese, \"Zn (OC)2\" genannten Molekule, wurden von Kollegen der Universitat Salerno synthetisiert. Strom Spannungs Messungen von Ag/ Zn(OC)2/p Si und Ag/Zn(OC)2/n Si Heterodioden wurden durchgefuhrt und mit Messungen an Referenzstrukturen mit den gleichen Metallkontakten, jedoch ohne die Einfugung der organischen Schicht, verglichen. Gutes Gleichrichtungsverhalten wurde fur beide Typen von Heterodioden mit der organischen Schicht, unabhangig von dem Siliziumsubstrat Dotierungstyp beobachtet. Dies bestatigt, dass die organische Schicht sowohl als als Elektronen als auch als Locherleiter verwendet werden kann. Die Zn(OC)2 Komplexe zeigten starke blaue Photolumineszenz in Losung und im Film.", "author_names": [ "Giovanni Landi" ], "corpus_id": 94122671, "doc_id": "94122671", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Organic semiconductor material and device characterization by low frequency noise and admittance spectroscopy of polymer: fullerene solar cells and silicon/organic thin film heterodiodes", "venue": "", "year": 2015 }, { "abstract": "", "author_names": [ "Paul Isaac Hagouel" ], "corpus_id": 19385335, "doc_id": "19385335", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Semiconductor material and device characterization [Book Review]", "venue": "IEEE Circuits and Devices Magazine", "year": 1999 }, { "abstract": "In this work, the electrical properties of Metal Insulator Semiconductor devices with graphene intercalated between the HfO2 dielectric and the gate electrode were studied at the nanometer scale (with a Conductive Atomic Force Microscope) and at device level. Their feasibility as ReRAM devices was also evaluated. At device level, when graphene is used as an interfacial layer, several resistive switching cycles were observed, meanwhile the standard structures without graphene did not show resistive switching behavior. Nanoscale analysis have shown that graphene avoids the complete microstructural damage of the oxide material during the forming process, demonstrating the protective role of the intercalated graphene layer in ReRAM structures.", "author_names": [ "S Claramunt", "A Ruiz", "Q Wu", "Marc Porti", "Montserrat Nafria", "Xavier Aymerich" ], "corpus_id": 232235443, "doc_id": "232235443", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "MIS structures with interfacial graphene for ReRAM applications: a nanoscale and device level characterization", "venue": "2020 Joint International EUROSOI Workshop and International Conference on Ultimate Integration on Silicon (EUROSOI ULIS)", "year": 2020 } ]

[ { "abstract": "In this paper, a four power semiconductor switch based three phase inverter is proposed for renewable energy source integration to a generalized microgrid system. The proposed topology b 4 of three phase inverter is investigated to make the commercial microgrid system to be cost effective and hardware optimized. A simple sine pulse width modulation based (SPWM) control strategy is proposed for the b 4 inverter topology instead of the traditional complex four switch based space vector techniques. The overall control structure is implemented using the Lyapunov function based nonlinear controller to track the inverter current directly in the a b c frame so that a specific amount of active and reactive grid power flow to the grid can be controlled in a decoupled manner along with low total harmonic distortion of grid currents in the presence of nonlinear load at the point of common coupling (PCC) A novel technique of using the spatial repetitive controller (SRC) is also proposed to eliminate the effect of midpoint voltage fluctuation of the dc link even in the case of asymmetrically split dc link capacitors without any extra voltage or current sensors unlike conventional methods. Detailed experimental results are provided to show the efficacy of the proposed hardware system for grid connected applications in the microgrid.", "author_names": [ "Souvik Dasgupta", "Shankar Narayan Mohan", "Sanjib Kumar Sahoo", "Sanjib Kumar Panda" ], "corpus_id": 23938996, "doc_id": "23938996", "n_citations": 98, "n_key_citations": 0, "score": 1, "title": "Application of Four Switch Based Three Phase Grid Connected Inverter to Connect Renewable Energy Source to a Generalized Unbalanced Microgrid System", "venue": "IEEE Transactions on Industrial Electronics", "year": 2013 }, { "abstract": "This paper presents modeling and control of a grid connected photovoltaic plant. The system consists of a PV cell, a Sepic DC DC converter used for Maximum Power Point Tracking (MPPT) a three phase grid converter. A nonlinear control technique of a three phase inverter is proposed to compensate unbalanced load currents. It allows full control of DC bus voltage, while controlling power flow from the PV cells to the system and guarantying balanced sinusoidal grid currents at unity power factor under varying solar irradiation. Moreover, a sliding mode control technique for a Sepic DC DC converter is used to extract the MPPT. The proposed control techniques have shown good performance. The system is validated using the \"Power system Blockset\" simulator under various values of the solar irradiation.", "author_names": [ "Abdelhamid Hamadi", "Salem Rahmani", "Kamal Al-Haddad", "Yasir A Al-Turki" ], "corpus_id": 45730736, "doc_id": "45730736", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "A three phase three wire grid connect photovoltaic energy source with Sepic converter to track the Maximum Power Point", "venue": "IECON 2011 37th Annual Conference of the IEEE Industrial Electronics Society", "year": 2011 }, { "abstract": "As the traditional resources have become rare, photovoltaic generation is developing quickly. The grid connected issue is one of the most importance problem in this field. The voltage source inverter usually uses LC or LCL as the filter. LCL filter, which can reduce the required filtered inductance and save the cost, is adopted to connect the grid in this paper. However, reasonable design of LCL filter needs consideration in order to achieve optimal effect. Meanwhile, systems with LCL filter need more complex control strategies. This paper firstly introduces a whole scheme of LCL filter design, then analyzes a two loop control method in detail which uses the capacitor current and grid current as the inner and outer control variable respectively. Detailed discussion about the role of the loops and the influence on the system caused by every parameter of the controller are given out. Finally experimental results verify the correctness of the analysis and availability of the control strategy.", "author_names": [ "Yun Chen", "Fei Liu" ], "corpus_id": 3104278, "doc_id": "3104278", "n_citations": 23, "n_key_citations": 0, "score": 0, "title": "Design and Control for Three Phase Grid Connected Photovoltaic Inverter with LCL Filter", "venue": "2009 IEEE Circuits and Systems International Conference on Testing and Diagnosis", "year": 2009 }, { "abstract": "Now a days due to recent advances in Photovoltaic (PV) panels, the demand on solar energy is increasing. In order to commercialize utilize solar energy properly we have connect it the grid. This paper deals with the design simulation of two stage converter system for integrating PV panel with the grid. It consists of PV panel, boost dc dc converter for stepping up the PV panel voltage, a VSI for converting dc to ac finally the grid. For operating the PV panel at maximum power point, Incremental Conductance algorithm is used the system also works under various changing environmental conditions. For controlling inverter output with respect to grid synchronous reference (dq) frame control is used. Three phase PLL is used to lock grid frequency phase with respect to inverter output. A low pass LC filter is modeled to remove high frequency harmonics from the inverter output transformer is used to provide galvanic isolation between inverter output grid. All the simulations are carried out in Simulink environment of MATLAB.", "author_names": [ "P Akash Pattanaik", "Naresh K Pilli", "Santosh kumar Singh" ], "corpus_id": 7069362, "doc_id": "7069362", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Design, simulation performance evaluation of three phase grid connected PV panel", "venue": "2015 IEEE Power, Communication and Information Technology Conference (PCITC)", "year": 2015 }, { "abstract": "This paper presents a Matlab/Simulink model of a 300 KW grid connected photovoltaic (PV) system. The system includes a 300 KW PV array, a maximum power point tracking boost converter using perturbation and observation (P&O) method and a grid connected inverter with its control system. An L filter is designed to smoothly connect the inverter to the utility grid. The boost converter controlled by a P&O algorithm is responsible for extracting the maximum power available to the PV array at any atmospheric conditions. The grid connected inverter is responsible for maintaining the DC link voltage constant. To accomplish the grid connected inverter task, a cascaded control structure is used; the outer control loop is the DC link voltage loop while the inner control loop is the direct axis inverter current component. A reactive power controller is used also to support the grid with a reactive power from the reserve inverter capacity. To control the reactive power transferred to the grid the quadrature axis inverter current component is controlled. A classical proportional integral (PI) and fuzzy logic controller are used to control the DC link voltage, direct axis current and quadrature axis current component. This paper also analyzes the characteristic of the power converter performance under PI control and fuzzy logic control connected to a very weak grid with minimum short circuit ratio (SCR)", "author_names": [ "Mohd Saifulizan Omar", "Amgad El-Deib", "Ahmad El Shafei", "M A El rhman", "M E Abdallah" ], "corpus_id": 23018031, "doc_id": "23018031", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Comparative study between PI and fuzzy logic controllers for three phase grid connected photovoltaic systems", "venue": "2016 Eighteenth International Middle East Power Systems Conference (MEPCON)", "year": 2016 }, { "abstract": "A single stage three phase Photovoltaic (PV) inverter guaranteeing Maximum Power Point Tracking (MPPT) and nearly unitary Power Factor (PF) in the connection to the Low Voltage (LV) grid, while acting as an Active Power Filter (APF) is developed in this paper. A Current Source Inverter (CSI) with an inductive DC link is used to connect the PV array to the grid, and the MPPT is achieved controlling directly the power in the DC link. Based on the power balance of the whole system, the grid current references are generated in a dq frame synchronized with the grid guaranteeing the mitigation of current harmonics produced by a non linear load connected to the grid. Simulation results are presented to confirm the proper operation of the system.", "author_names": [ "Thomas Geury", "Sonia Ferreira Pinto", "Johan J C Gyselinck" ], "corpus_id": 38844822, "doc_id": "38844822", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Three phase power controlled PV current source inverter with incorporated active power filtering", "venue": "IECON 2013 39th Annual Conference of the IEEE Industrial Electronics Society", "year": 2013 }, { "abstract": "Single phase grid connected inverters are widely used to connect small scale distributed renewable resources to the grid. However, unlike a three phase system, control for a single phase inverter is more challenging, especially when the inverter is used with an LCL filter. This paper proposes a novel recurrent neural network based vector control method for a single phase inverter with an LCL filter. The neural network is trained based on adaptive dynamic programming principle, and the objective of the training is to approximate optimal control. The Levenberg Marquardt plus forward accumulation through time algorithm is developed for training the proposed recurrent neural network controller. The neural network vector control approach is compared with the conventional control methods, including the conventional PI based vector control method and the PR based control technique for single phase inverters. Both the simulations and hardware experiments demonstrate the great advantages of the proposed neural network vector control over the conventional control methods. Compared with conventional control methods, the neural network control allows for low sampling rate and low switching frequency, while maintaining high performance in controlling a single phase inverter. In addition, no specific damping policy is required to implement the proposed neural network vector control for an LCL filter based single phase inverter. The study shows that the neural network vector control is a robust control method, and can provide better control performance even when facing system parameter changes, while under this case, both the conventional PI based vector control and the PR based control failed to yield the acceptable results.", "author_names": [ "Xingang Fu", "Shuhui Li" ], "corpus_id": 23707208, "doc_id": "23707208", "n_citations": 88, "n_key_citations": 4, "score": 0, "title": "Control of Single Phase Grid Connected Converters With LCL Filters Using Recurrent Neural Network and Conventional Control Methods", "venue": "IEEE Transactions on Power Electronics", "year": 2016 }, { "abstract": "This paper describes the main inverter topologies intended to connect the renewable energy resources to the grid utility. It shows the circuit configuration of the fullbridge three phase inverter, flyback inverter, Z Source inverter and neutral point clamped inverter, and it also discusses their advantages and disadvantages for each application. At last, a list of non common topologies that handle specific issues of renewable resources is presented.", "author_names": [ "Hendriks Delesposte Paulino", "P J M Menegaz", "Domingos Savio Lyrio Simonetti" ], "corpus_id": 22432191, "doc_id": "22432191", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "A review of the main inverter topologies applied on the integration of renewable energy resources to the grid", "venue": "XI Brazilian Power Electronics Conference", "year": 2011 }, { "abstract": "This paper describes and evaluates an adaptive neuro fuzzy inference system (ANFIS) based energy management system (EMS) of a grid connected hybrid system. It presents a wind turbine (WT) and photovoltaic (PV) solar panels as primary energy sources, and an energy storage system (ESS) based on hydrogen (fuel cell FC hydrogen tank and electrolyzer) and battery. All of the energy sources use dc/dc power converters in order to connect them to a central DC bus. An ANFIS based supervisory control system determines the power that must be generated by/stored in the hydrogen and battery, taking into account the power demanded by the grid, the available power, the hydrogen tank level and the state of charge (SOC) of the battery. Furthermore, an ANFIS based control is applied to the three phase inverter, which connects the hybrid system to grid. Otherwise, this new EMS is compared with a classical EMS composed of state based supervisory control system based on states and inverter control system based on PI controllers. Dynamic simulations demonstrate the right performance of the ANFIS based EMS for the hybrid system under study and the better performance with respect to the classical EMS.", "author_names": [ "Pablo Garcia-Trivino", "Carlos Andres Garcia", "Luis M Fernandez", "Francisco Llorens", "Francisco Jurado" ], "corpus_id": 19031930, "doc_id": "19031930", "n_citations": 157, "n_key_citations": 5, "score": 0, "title": "ANFIS Based Control of a Grid Connected Hybrid System Integrating Renewable Energies, Hydrogen and Batteries", "venue": "IEEE Transactions on Industrial Informatics", "year": 2014 }, { "abstract": "The increasing use of grid connected inverters to connect renewable energy sources to a power grid will have globally important effect on grid performance. A mismatch between the grid and inverter impedance may cause harmonic resonances, which can lead to instability of the grid and disruption of inverter operation. The grid dynamics vary over time, so the inverter should adapt to the varying conditions to ensure system stability. Recent studies have presented online methods to adaptively control the grid connected inverters in the sequence domain. This paper extends those previous studies, and presents an online method to adaptively control the inverters in the dq domain. In the method, the grid impedance is measured online using a pseudo random binary sequence (PRBS) injection and Fourier techniques. The inverter control parameters are then adaptively adjusted based on the measurements. This paper presents experimental results based on a three phase photovoltaic inverter using power hardware in the loop (PHIL) setup.", "author_names": [ "Roni Luhtala", "Tuomas Messo", "Tommi Reinikka", "Jussi Sihvo", "Tomi Roinila", "Matti K Vilkko" ], "corpus_id": 46043553, "doc_id": "46043553", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "Adaptive control of grid connected inverters based on real time measurements of grid impedance: DQ domain approach", "venue": "2017 IEEE Energy Conversion Congress and Exposition (ECCE)", "year": 2017 } ]

[ { "abstract": "Organic inorganic hybrid perovskites have been intensively researched in the past decade for their optoelectronic properties. The emergence of Ruddlesden Popper perovskites, which have mixed dimensionality, has heralded new opportunities for tailor made semiconductors that combine enhanced stability with useful properties between those of 2D and 3D systems. Inspired by advances in 2D materials research, there is growing interest in molecularly thin versions of these hybrid perovskites, owing to their ease of incorporation into electronic devices. There is, thus, a need to understand thickness dependent electrical, excitonic and phononic properties that go beyond quantum confinement effects. Recent studies have shown that, apart from tuning the dimensionality of the system, fine tuning its thickness also helps to optimize performance in different applications, ranging from third harmonic generation to photodetectors and spintronics. Owing to their layered structure, the properties of 2D perovskites can be controlled by tuning their thickness. This Review surveys how fine tuning the thickness of 2D perovskites from the sub micrometre to the molecularly thin regime helps to optimize their electrical and optical properties for use in different applications.", "author_names": [ "Kai Leng", "Wei Fu", "Yanpeng Liu", "Manish Chhowalla", "Kian Ping Loh" ], "corpus_id": 214696302, "doc_id": "214696302", "n_citations": 40, "n_key_citations": 0, "score": 1, "title": "From bulk to molecularly thin hybrid perovskites", "venue": "Nature Reviews Materials", "year": 2020 }, { "abstract": "Due to their layered structure, two dimensional Ruddlesden Popper perovskites (RPPs) composed of multiple organic/inorganic quantum wells, can in principle be exfoliated down to few and single layers. These molecularly thin layers are expected to present unique properties with respect to the bulk counterpart, due to increased lattice deformations caused by interface strain. Here, we have synthesized centimetre sized, pure phase single crystal RPP perovskites (CH3(CH2)3NH3)2(CH3NH3)n 1PbnI3n+1 (n 1 4) from which single quantum well layers have been exfoliated. We observed a reversible shift in excitonic energies induced by laser annealing on exfoliated layers encapsulated by hexagonal boron nitride. Moreover, a highly efficient photodetector was fabricated using a molecularly thin n 4 RPP crystal, showing a photogain of 105 and an internal quantum efficiency of ~34% Our results suggest that, thanks to their dynamic structure, atomically thin perovskites enable an additional degree of control for the bandgap engineering of these materialsReversible structural surface relaxation under laser exposure is observed for monolayers of 2D metal halide perovskites. These structural changes also induce reversible shifts in the photoluminescence peaks of these materials.", "author_names": [ "Kai Leng", "Ibrahim Abdelwahab", "Ivan A Verzhbitskiy", "Mykola Telychko", "Leiqiang Chu", "Wei Fu", "Xiao Chi", "Na Guo", "Zhihui Chen", "Zhongxin Chen", "Chun Zhang", "Qing-Hua Xu", "Jiong Lu", "Manish Chhowalla", "Goki Eda", "Kian Ping Loh" ], "corpus_id": 205566073, "doc_id": "205566073", "n_citations": 138, "n_key_citations": 1, "score": 0, "title": "Molecularly thin two dimensional hybrid perovskites with tunable optoelectronic properties due to reversible surface relaxation", "venue": "Nature Materials", "year": 2018 }, { "abstract": "In layered hybrid perovskites like (BA) 2 PbI 4 (BA C 4 H 9 NH 3 electrons and holes are considered to be confined in atomically thin two dimensional (2D) Pb I inorganic layers. These inorganic layers are electronically isolated from each other in the third dimension by the insulating organic layers. Our experimental findings suggest the presence of electronic interaction between the inorganic layers in some parts of the single crystals. The extent of this interaction is reversibly tuned by intercalation of organic and inorganic molecules in the layered perovskite single crystals. Consequently, optical absorption and emission properties switch reversibly with intercalation. Furthermore, increasing the distance between inorganic layers by increasing the length of the organic spacer cations systematically decreases these electronic interactions. This finding that the parts of the layered hybrid perovskites are not strictly electronically 2D is critical for understanding the electronic, optical and optoelectronic properties of these technologically important materials.", "author_names": [ "Tariq Sheikh", "Vaibhav V Nawale", "Nithin Pathoor", "Chinmay Phadnis", "Arindam Chowdhury", "Angshuman Nag" ], "corpus_id": 214787474, "doc_id": "214787474", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Molecular Intercalation and Electronic Two Dimensionality in Layered Hybrid Perovskites.", "venue": "Angewandte Chemie", "year": 2020 }, { "abstract": "Abstract Organic inorganic hybrid perovskites have potential applications in flexible electronics based on solution processing polycrystalline thin films. This article reports an emerging phenomenon: mechanically tunable spin orbit coupling (SOC) in flexible perovskite solar cells under elastic bending. Polarization dependent photocurrent studies show that mechanical bending increases the orbit orbit interaction, shown as an enhanced SOC, and consequently boosting the intersystem crossing to convert optically generated bright states (which are allowed to recombine) into dark states (which are forbidden to recombine) in flexible perovskite solar cells [PET/ITO/PEDOT:PSS/MAPbI3 xClx/PCBM/PEI/Ag] Simultaneously, the photocurrent is increased from 15.39 mA/cm2 to 22.0 mA/cm2 by 43% upon such elastic bending with the curvature radius of 4.2 mm. It is further found that introducing mechanical stress leads to both grain boundary interaction and grain deformation shown as the decreased defects at grain boundaries through thermal admittance spectroscopy and the elastic strain verified by X ray diffraction measurement. The capacitance frequency characteristics indicate that applying this mechanical stress causes an increase on the bulk polarization by introducing grain boundary interaction and grain deformation. This provides necessary condition to realize mechanically tunable SOC effects in perovskites via electric magnetic coupling. Essentially, mechanically tunable SOC effects present new mechanisms to control the optoelectronic properties in flexible perovskite electronic devices.", "author_names": [ "Haomiao Yu", "Miaosheng Wang", "Changfeng Han", "Kai Wang", "Bin Hu" ], "corpus_id": 210258949, "doc_id": "210258949", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Mechanically tuning spin orbit coupling effects in organic inorganic hybrid perovskites", "venue": "", "year": 2020 }, { "abstract": "Hybrid (organic inorganic) multication lead halide perovskites hold promise for a new generation of easily processable solar cells. Best performing compositions to date are multiple cation solid alloys of formamidinium (FA) methylammonium (MA) cesium, and rubidium lead halides which provide power conversion efficiencies up to around 22% Here, we elucidate the atomic level nature of Cs and Rb incorporation into the perovskite lattice of FA based materials. We use 133Cs, 87Rb, 39K, 13C, and 14N solid state MAS NMR to probe microscopic composition of Cs Rb K MA and FA containing phases in double triple and quadruple cation lead halides in bulk and in a thin film. Contrary to previous reports, we have found no proof of Rb or K incorporation into the 3D perovskite lattice in these systems. We also show that the structure of bulk mechanochemical perovskites bears close resemblance to that of thin films, making them a good benchmark for structural studies. These findings provide fundamental understanding of previously reported excellent photovoltaic parameters in these systems and their superior stability.", "author_names": [ "Dominik Jozef Kubicki", "Daniel Prochowicz", "Albert Hofstetter", "Shaik M Zakeeruddin", "Michael Gratzel", "Lyndon Emsley" ], "corpus_id": 207182928, "doc_id": "207182928", "n_citations": 190, "n_key_citations": 1, "score": 0, "title": "Phase Segregation in Cs Rb and K Doped Mixed Cation (MA)x(FA)1 xPbI3 Hybrid Perovskites from Solid State NMR", "venue": "Journal of the American Chemical Society", "year": 2017 }, { "abstract": "Current voltage hysteresis is a major issue for normal architecture organo halide perovskite solar cells. In this manuscript we reveal a several angstrom thick methylammonium iodide rich interface between the perovskite and the metal oxide. Surface functionalization via self assembled monolayers allowed us to control the composition of the interface monolayer from Pb poor to Pb rich, which, in parallel, suppresses hysteresis in perovskite solar cells. The bulk of the perovskite films is not affected by the interface engineering and remains highly crystalline in the surface normal direction over the whole film thickness. The subnanometer structural modifications of the buried interface were revealed by X ray reflectivity, which is most sensitive to monitor changes in the mass density of only several angstrom thin interfacial layers as a function of substrate functionalization. From Kelvin probe force microscopy study on a solar cell cross section, we further demonstrate local variations of the potential on different electron transporting layers within a solar cell. On the basis of these findings, we present a unifying model explaining hysteresis in perovskite solar cells, giving an insight into one crucial aspect of hysteresis for the first time and paving way for new strategies in the field of perovskite based opto electronic devices.", "author_names": [ "Johannes Will", "Yi Hou", "Simon Scheiner", "Ute Pinkert", "Ilka M Hermes", "Stefan A L Weber", "Andreas Hirsch", "Marcus Halik", "Christoph J Brabec", "Tobias Unruh" ], "corpus_id": 206474552, "doc_id": "206474552", "n_citations": 23, "n_key_citations": 0, "score": 0, "title": "Evidence of Tailoring the Interfacial Chemical Composition in Normal Structure Hybrid Organohalide Perovskites by a Self Assembled Monolayer.", "venue": "ACS applied materials interfaces", "year": 2018 }, { "abstract": "Controlling the structure of layered hybrid metal halide perovskites, such as the Ruddlesden Popper (R P) phases, is challenging because of their tendency to form mixtures of varying composition. Colloidal growth techniques, such as antisolvent precipitation, form dispersions with properties that match bulk layered R P phases, but controlling the composition of these particles remains challenging. Here, we explore the microstructure of particles of R P phases of methylammonium lead iodide prepared by antisolvent precipitation from ternary mixtures of alkylammonium cations, where one cation can form perovskite phases (CH3NH3+ and the other two promote layered structures as spacers (e.g. C4H9NH3+ and C12H25NH3+ We determine that alkylammonium spacers pack with constant methylene density in the R P interlayer and exclude interlayer solvent in dispersed colloids, regardless of length or branching. Using this result, we illustrate how the competition between cations that act as spacers between layers, or as grain terminating ligands, determines the colloidal microstructure of layered R P crystallites in solution. Optical measurements reveal that quantum well dimensions can be tuned by engineering the ternary cation composition. Transmission synchrotron wide angle X ray scattering and small angle neutron scattering reveal changes in the structure of colloids in solvent and after deposition into thin films. In particular, we find that spacers can alloy between R P layers if they share common steric arrangements, but tend to segregate into polydisperse R P phases if they do not mix. This study provides a framework to compare the microstructure of colloidal layered perovskites and suggests clear avenues to control phase and colloidal morphology.", "author_names": [ "Clayton J Dahlman", "Naveen R Venkatesan", "Patrick T Corona", "Rhys M Kennard", "Lingling Mao", "Noah C Smith", "Jiamin Zhang", "Ram Seshadri", "Matthew E Helgeson", "Michael L Chabinyc" ], "corpus_id": 221282508, "doc_id": "221282508", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Structural Evolution of Layered Hybrid Lead Iodide Perovskites in Colloidal Dispersions.", "venue": "ACS nano", "year": 2020 }, { "abstract": "In this study, we examine the effects of changing organic cation concentrations on the efficiency and photophysical implications of exciton trapping in two dimensional hybrid lead iodide self assembled quantum wells (SAQWs) We show that increasing the concentration of alkyl and aryl ammonium cations causes the formation of SAQWs at a liquid liquid interface to possess intense, broadband subgap photoluminescence (PL) spectra. Electron microscopy, X ray diffraction, and X ray photoelectron spectroscopic studies suggest that materials formed under these cation concentrations possess morphologies consistent with inhibited crystallization kinetics but exhibit qualitatively similar bulk chemical bonding to nonluminescent materials stabilized in the same structure from precursor solutions containing lower cation concentrations. Temperature and power dependent PL spectra suggest that the broadband subgap light emission stems from excitons self trapped at defect sites, which we assign as edge like, collective I vacancies using a simple model of the chemical equilibrium driving material self assembly. These results suggest that changes to the availability of molecular cations can suitably control the light emission properties of self assembled hybrid organic inorganic materials in ways central to their applicability in lighting technologies.", "author_names": [ "Adedayo M Sanni", "Aaron S Rury" ], "corpus_id": 228168259, "doc_id": "228168259", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Kinetic Molecular Cationic Control of Defect Induced Broadband Light Emission in 2D Hybrid Lead Iodide Perovskites.", "venue": "The journal of physical chemistry letters", "year": 2020 }, { "abstract": "Gas induced growth of organic inorganic hybrid perovskites, especially methylammonium lead iodide (MAPbI3) has shown interesting properties and applications in the area of optoelectronics. In this report, we introduce a method of gas induced band gap engineering of thin films of MAPbI3 due to systematic dimensional confinement deconfinement along the crystallographic c axis of growing MAPbI3. Interestingly, such restricted growth phenomenon was observed when hexylammonium lead iodide (2D hybrid perovskite) film was exposed to methylamine gas instead of conventional PbI2 film methylamine gas precursor pair. Hexylamine, formed due to cation exchange reaction interacts selectively with the Pb centres of growing MAPbI3 crystals and this induces an enormous restriction in the growth of MAPbI3 along crystallographic c direction, leading to a unique sheet type MAPbI3 film having a much higher band gap (2.18 eV) compared to conventional bulk MAPbI3. However, careful control of exposure timing gradually evaporates the hexylamine leading to systematic dimensional deconfinement enabling modulation of band gap from 2.18 eV to 1.69 eV. An interplay of adsorption and desorption of hexylamine is also utilized for generating patterns of two different fluorescent hybrid perovskite materials in a single pixel. This new mechanistic investigation highlighting gas induced interplay of dimensional confinement deconfinement associated with band gap tuning provides smooth thin films which can be used to develop optoelectronic devices.", "author_names": [ "Sayantan Sasmal", "Shilendra Kumar Sharma", "Soumyo Chatterjee", "Amlan J Pal", "Shuvan Prashant Turaga", "Andrew A Bettiol", "Raj Ganesh S Pala", "Sri Sivakumar", "Suresh Valiyaveettil" ], "corpus_id": 204851243, "doc_id": "204851243", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Gas Induced Confinement Deconfinement Interplay in Organic Inorganic Hybrid Perovskite Thin Film Results in Systematic Band Modulation.", "venue": "ACS applied materials interfaces", "year": 2019 }, { "abstract": "Knowledge of the mechanism of formation, orientation, and location of phases inside thin perovskite films is essential to optimize their optoelectronic properties. Among the most promising, low toxicity, lead free perovskites, the tin based ones are receiving much attention. Here, an extensive in situ and ex situ structural study is performed on the mechanism of crystallization from solution of 3D formamidinium tin iodide (FASnI(3) 2D phenylethylammonium tin iodide (PEA(2)SnI(4) and hybrid PEA(2)FA(n) 1)Sn(n)I(3)(n)+1) Ruddlesden Popper perovskites. Addition of small amounts of low dimensional component promotes oriented 3D like crystallite growth in the top part of the film, together with an aligned quasi 2D bottom rich phase. The sporadic bulk nucleation occurring in the pure 3D system is negligible in the pure 2D and in the hybrid systems with sufficiently high PEA content, where only surface crystallization occurs. Moreover, tin based perovskites form through a direct conversion of a disordered precursor phase without forming ordered solvated intermediates and thus without the need of thermal annealing steps. The findings are used to explain the device performances over a wide range of composition and shed light onto the mechanism of the formation of one of the most promising Sn based perovskites, providing opportunities to further improve the performances of these interesting Pb free materials.", "author_names": [ "Jingjin Dong", "Shuyan Shao", "Simon Kahmann", "Alexander J Rommens", "Daniel Hermida-Merino", "Gert H ten Brink", "Maria Antonietta Loi", "Giuseppe Portale" ], "corpus_id": 216444434, "doc_id": "216444434", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "Mechanism of Crystal Formation in Ruddlesden Popper Sn Based Perovskites", "venue": "", "year": 2020 } ]

[ { "abstract": "During the pandemic, Infineon's supply chain impacts were largely defined by governmental decisions that affected transit times. Later, one of the major impacts came from demand reductions for semiconductors. Therefore, a System Dynamics (SD) Model that investigates the interdependence between infections and governmental strictness in restrictions using an extended SEIR model was developed in AnyLogic. For the quantification of governmental measures, the Oxford Blavatnik University coronavirus government response tracker was used. Based on this conceptual output, the resulting transit time increases have been connected with the strictness of these measures. The model links reductions in semiconductor demand to the duration of lockdowns as indicated by the current measures. The findings show that demand shocks and transit time delays can be buffered using flexible capacities and safety stocks.", "author_names": [ "B Feng", "Sin-Bom Kim", "Sanja Lazarova-Molnar", "Z Zheng", "T Roeder", "Renee M Thiesing" ], "corpus_id": 230115578, "doc_id": "230115578", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "FORECASTING SUPPLY CHAIN IMPACT BY PREDICTING GOVERNMENTAL DECISIONS IN THE COVID 19 PANDEMIC", "venue": "", "year": 2020 }, { "abstract": "With the heightened volatility in stock prices during the Covid 19 pandemic, the need for price forecasting has become more critical. We investigated the forecast performance of four models including Long Short Term Memory, XGBoost, Autoregression, and Last Value on stock prices of Facebook, Amazon, Tesla, Google, and Apple in COVID 19 pandemic time to understand the accuracy and predictability of the models in this highly volatile time region. To train the models, the data of all stocks are split into train and test datasets. The test dataset starts from January 2020 to April 2021 which covers the COVID 19 pandemic period. The results show that the Autoregression and Last value models have higher accuracy in predicting the stock prices because of the strong correlation between the previous day and the next day's price value. Additionally, the results suggest that the machine learning models (Long Short Term Memory and XGBoost) are not performing as well as Autoregression models when the market experiences high volatility.", "author_names": [ "Navid Mottaghi", "Sara Farhangdoost" ], "corpus_id": 233864854, "doc_id": "233864854", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Stock Price Forecasting in Presence of Covid 19 Pandemic and Evaluating Performances of Machine Learning Models for Time Series Forecasting", "venue": "", "year": 2021 }, { "abstract": "Starting with the differences between forecasting and prediction and going deeper into prediction, a knowledge based model is presented The evolution of the stocks markets are analyzed, as well as how the epidemics and pandemics prior to the stock markets have affected them and how it is currently being affected by covid 19 The defined model is applied to a use case using Case Based Reasoning (CBR) it makes an analogy between the 2008 crisis with the covid 19 crisis in 2020 to predict whether the stock markets will take more or less time to recover", "author_names": [ "Antonio Lorenzo Sanchez", "Jose Angel Olivas" ], "corpus_id": 228955199, "doc_id": "228955199", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Intelligent data analysis of the influence of COVID 19 on the stock market using Case Based Reasoning", "venue": "J. Comput. Sci. Technol.", "year": 2020 }, { "abstract": "Currently the world is facing a global problem in the form of the COVID 19 pandemic. The spread of the COVID 19 outbreak continues to move significantly, especially in Indonesia. Since it was announced by President Joko Widodo in early March until now, the number of positive cases of COVID 19 has reached 418.375 cases. The impact of COVID 19 is a serious threat to the global economy. COVID 19 attacks the movement of stocks on global exchanges. The Composite Stock Price Index (IHSG) has touched its lowest level in history due to COVID 19. COVID 19 can be considered as an event that occurs out of control, so of course it will affect various sectors, particularly the economic sector, by spreading fear for investors and creating uncertainty in the global economy. The purpose of this study is to determine the impact of COVID 19 on the IHSG and to build a model that can be used for forecasting. The analytical method used is intervention analysis. The intervention model is used to model data that contains shocks. In this case, the suspected shock is the COVID 19. The intervention function used is the step function. Furthermore, risk measurement will be carried out so that risk is at a controllable level. Measurable risk can reduce the chance of loss that may be borne by investors. The method used is Value at Risk (VaR) The risk measurement is applied to the outcome forecasting data from the intervention model. Based on the results analysis, intervention model shows that COVID 19 has had an impact and a harsh slap on IHSG. Forecasting results from the intervention model have a good accuracy, with MAPE from in sample is 0,76% Then the forecasting results from the intervention model have a Value at Risk (VaR) which ranges from 0,45% to 1,96% with a confidence level of 95% Keywords IHSG, Intervention Analysis, Value at Risk", "author_names": [ "Andrea Tri Rian Dani", "Alifta Ainurrochmah", "Narita Yuri Adrianingsih" ], "corpus_id": 234592986, "doc_id": "234592986", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Analysis for Evaluating the Impact of COVID 19 on the Indonesian Composite Stock Price Index", "venue": "", "year": 2020 }, { "abstract": "Starting with the differences between forecasting and prediction and going deeper into prediction, a knowledge based model is presented. The evolution of the stocks markets are analyzed, as well as how the epidemics and pandemics prior to the stock markets have affected them and how it is currently being affected by covid 19. The defined model is applied to a use case using Case Based Reasoning (CBR) it makes an analogy between the 2008 crisis with the covid 19 crisis in 2020 to predict whether the stock markets will take more or less time to recover.", "author_names": [ "Antonio T Lorenzo", "Jose Angel Olivas" ], "corpus_id": 232137891, "doc_id": "232137891", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Intelligent Data Analysis of the Influence of COVID 19 on the Stock Market using Case Based Reasoning Analisis Inteligente de los Datos de la Influencia de la COVID 19 sobre los Mercados de Valores", "venue": "", "year": 2020 }, { "abstract": "The stock market is an organized body where public companies offer their stocks through initial public offerings and traders buy/sell these stocks so as to obtain profits. It is dynamic and volatile in nature which makes the task of stock market trend prediction a complex problem. In recent times, the COVID 19 pandemic has made this task even harder. With the rising number of COVID 19 cases across the globe, the market has never been more volatile. This has resulted in the poor performance of various traditional trend prediction algorithms because these algorithms do not account for the impact of the pandemic on the stock market trends. The proposed work aims to enhance the stock market prediction ability of various common prediction models by taking into account the factors related to COVID 19. The forecasting techniques analysed are Decision Tree Regressor, Random Forest Regressor and Support Vector Regressor (SVR) Currently the most affected countries by COVID 19 are the United States of America, India and Russia. Therefore we have analysed the prediction performance of various approaches discussed in this paper on S&P 500 Index, Nifty50 Index and RTS Index using Root Mean Square Error (RMSE) and Mean Absolute Percentage Error (MAPE) Results obtained showcase that all the techniques used perform better when the COVID 19 features were included.", "author_names": [ "Rajni Jindal", "Nikhil Bansal", "Nitin Chawla", "Sanskriti Singhal" ], "corpus_id": 233226237, "doc_id": "233226237", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Improving Traditional Stock Market Prediction Algorithms using Covid 19 Analysis", "venue": "2021 International Conference on Emerging Smart Computing and Informatics (ESCI)", "year": 2021 }, { "abstract": "The affliction caused by the COVID 19 Pandemic is diverse from other disasters seen so far. Supply chain industries are facing unique challenges in fulfilling the essential needs of the people. The objective of the paper is to analyze the supply and demand of essentials during pre pandemic and post pandemic lockdowns using machine learning algorithms. This helps for supply chain industries in forecasting and managing the supply and demand of essential stocks for the future. Data are analyzed using prediction algorithms to check the actual and predicted values. The clustering algorithm along with rolling mean is used for half yearly data of 2019 and 2020 to identify the sales of different categories of essential commodities. This paper aims at applying intelligence in predicting various categories of sales by providing timely information for B2B Industries during the time of disasters.", "author_names": [ "P Anitha", "Malini M Patil", "Rekha B Venkatapur" ], "corpus_id": 235410921, "doc_id": "235410921", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "COVID 19 Effect on Supply and Demand of Essential Commodities using Unsupervised Learning Method", "venue": "Journal of The Institution of Engineers (India) Series B", "year": 2021 }, { "abstract": "The impact of Covid 19 has triggered the current global economic downturn affecting all aspects of the economy including the Islamic stock index. This study aims to determine the model for forecasting the index. The Islamic stock index is used in six countries through adopting the Autoregressive Conditional Heteroscedasticity Generalized Autoregressive Conditional Heteroscedasticity (ARCH GARCH) method on daily data over the period January 2020 to October 2020. The risk level of each index was found to be influenced by the residual value from the previous day. The forecasting revealed the tendency of all stock prices to decline. These are associated with impacts of the Covid 19 pandemic on current and future economic performance. Investors need to assess the sector's fundamentals and the individual stocks in question, that are potential winners with propensity to recover and grow well once the market rebounds. They also need to continuously track the development of the pandemic in tandem with the economic sector and thus make the necessary adjustments at every step of the investment process. (c) 2021 Penerbit Universiti Kebangsaan Malaysia. All rights reserved.", "author_names": [ "Faizul Mubarok", "Mohammad Arif" ], "corpus_id": 235351665, "doc_id": "235351665", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Pandemic Attack and Islamic Stocks Index: A Cross Country Analysis", "venue": "", "year": 2021 }, { "abstract": "The stock market is volatile and complicated, especially in 2020. Because of a series of global and regional \"black swans\" such as the COVID 19 pandemic, the U.S. stock market triggered the circuit breaker three times within one week of March 9 to 16, which is unprecedented throughout the history. Affected by the whole circumstance, the stock prices of individual corporations also plummeted by rates that were never predicted by any pre developed forecasting models. It reveals that there was a lack of satisfactory models that could predict the changes of stocks prices when catastrophic, highly unlikely events occur. To fill the void of such models and to help prevent investors from heavy losses during uncertain times, this paper aims to capture the movement pattern of stock prices under anomalous circumstances. First, we detect outliers in sequential stock prices by fitting a standard ARIMA model and identifying the points where predictions deviate significantly from actual values. With the selected data points, we train ARIMA and LSTM models at the single stock level, industry level, and the general market level, respectively. Since the public moods affect the stock market tremendously, a sentiment analysis is also incorporated into the models in the form of sentiment scores, which are converted from comments about specific stocks on Reddit. Based on 100 companies' stock prices in the period of 2016 to 2020, the models achieve an average prediction accuracy of 98% which can be used to optimize existing prediction methodologies.", "author_names": [ "Jinlong Ruan", "Wei Wu", "Jiebo Luo" ], "corpus_id": 232374054, "doc_id": "232374054", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Stock Price Prediction Under Anomalous Circumstances", "venue": "2020 IEEE International Conference on Big Data (Big Data)", "year": 2020 }, { "abstract": "Considerable theoretical and empirical evidence links price comovements with the behavior of retail investors. Nevertheless, when predicting stock return correlations, research has focused on the leverage effect. We propose a new model of realized covariances that allows exogenous predictors to influence the correlation dynamics while ensuring the predicted matrices' positive definiteness. Using this model, we provide evidence for the predictive power of sentiment and attention measures obtained from social media and web search query data for the correlations of 35 Dow Jones stocks. At the one day forecasting horizon, these findings are confirmed by value at risk forecasts.", "author_names": [ "Daniele Ballinari" ], "corpus_id": 230652692, "doc_id": "230652692", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Retail Investors' Trading Activity and the Predictability of Stock Return Correlations", "venue": "", "year": 2020 } ]

[ { "abstract": "Free carrier absorption (FCA) in a semiconductor provides information about the band on which the free carriers reside, and in the classical limit, follows the o 2 law with o being the photon frequency. In hybrid organic inorganic perovskites (HOIPs) the colossal Rashba effect (RE) results in a new band dispersion, characterized by wavevector |k| k0 of band extremum and effective mass m* Here we show that the colossal RE in two dimensional HOIPs greatly enhances phonon assisted FCA with a modified frequency dependence and induces a direct transition between the subbands with a resonance at o 4R 22k02/m* which, under a magnetic field, exhibits a strong oscillatory magnetic circular dichroism (MCD) The MCD spectrum allows a complete and reliable determination of k0 and m* for conduction and valence bands in HOIPs and helps reveal the microscopic mechanism of their outstanding photovoltaic performance.", "author_names": [ "Zhi-Gang Yu" ], "corpus_id": 46781994, "doc_id": "46781994", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Oscillatory Magnetic Circular Dichroism of Free Carrier Absorption and Determination of the Rashba Dispersions in Hybrid Organic Inorganic Perovskites.", "venue": "The journal of physical chemistry letters", "year": 2018 }, { "abstract": "By incorporating various halogen (F, Cl, Br, and I) substituted chiral organic cations, the effects of chiral molecules on chiroptical properties of hybrid organic inorganic perovskite (HOIP) are investigated. Among them, the HOIP having Cl substituted chiral cation exhibits the highest circular dichroism (CD) and circular polarized luminescence (CPL) intensities, indicating the existence of the largest rotatory strength, whereas the F substituted one shows the weakest intensities. The observed modulation can be correlated to the varied magnetic transition dipole of HOIPs, which is sensitive to the d spacing between inorganic layers and the halogen halogen interaction between organic cations and the inorganic sheets. Although a larger angular momentum of organic cation is expected as the atomic number of the para substituent increases, the simultaneous increase in atom size enlarges the d spacing of the HOIPs, thereby lowering the magnetic transition dipole. However, the strong halogen halogen interaction existing in Cl substituted system leads to a significantly increased rotational strength. These offsetting effects meet the optimal CD and CPL intensity with chlorine substitution, rendering the rotatory strength of HOIPs arranged in the order of (ClMBA) 2 PbI 4 (BrMBA) 2 PbI 4 (IMBA) 2 PbI 4 (MBA) 2 PbI 4 (FMBA) 2 PbI 4 The modulation of the magnetic transition dipoles of HOIP paves the new avenue for designing hybrid perovskite based spintronic devices.", "author_names": [ "Lan-Sheng Yang", "Yi-Hung Liu", "Pi-Tai Chou", "Ching-Wen Chiu" ], "corpus_id": 236471805, "doc_id": "236471805", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Tuning the Circular Dichroism and Circular Polarized Luminescence Intensities of Chiral 2D Hybrid Organic Inorganic Perovskites through Halogenation of the Organic Ions.", "venue": "Angewandte Chemie", "year": 2021 }, { "abstract": "Metal halide perovskites are recently emerging as the promising alternative for CPL detection owing to their CPL sensitive property induced by chiral organics and efficient charge transport of inorganic frameworks. However, most of these reported chiral perovskites involve high concentrations of toxic Pb which will become the potential bottleneck for their further application. Herein, we successfully developed two lead free halide double perovskites, R b MPA] 4 AgBiI 8 R b MPA R b methylphenethylammonium, 1 R and S b MPA] 4 AgBiI 8 S b MPA S b methylphenethylammonium, 1 S Circular dichroism measurements reveal that these perovskites exhibit notable chirality induced by organic cations to distinguish different polarization states of CPL photons. Significantly, they present unique chiral polar photovoltaic, and resulting self powered CPL detection without an external power source is unprecedentedly achieved. Furthermore, an anisotropy factor up to 0.3 is acquired for the self powered CPL detection, reaching the highest value among reported chiral perovskites. This work suggests hybrid double perovskites are promising photoelectronic candidates, and provides a new approach for exploring new \"green\" circularly polarized light sensitive materials with high perfromance", "author_names": [ "Dong Li", "Xitao Liu", "Wentao Wu", "Yunyan Peng", "Sangen Zhao", "Lina Li", "Maochun Hong", "Junhua Luo" ], "corpus_id": 229351622, "doc_id": "229351622", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Chiral lead free hybrid perovskites for self powered circularly polarized light detection.", "venue": "Angewandte Chemie", "year": 2020 }, { "abstract": "Using circularly polarised broadband transient absorption, time resolved circular photoluminescence, and transient Faraday rotation spectroscopy, we report that spin dependent interactions have a significant impact on exciton energies and spin depolarisation times in layered Ruddlesden Popper hybrid metal halide perovskites. In BA2FAPb2I7, we report that room temperature spin lifetimes are largest (3.2 ps) at a carrier density of ~1015 cm 3, while the exciton depolarisation rate increases with exciton density. This indicates that many body interactions reduce spin lifetimes, and outcompete the effect of D'yakonov Perel precessional relaxation that has been previously reported at lower carrier densities. samples. We further observe a dynamic circular dichroism that arises from a photoinduced polarisation in the exciton distribution between total angular momentum states. Our findings provide fundamental, application relevant insights into the spin dependent exciton exciton interactions in layered hybrid perovskites.", "author_names": [ "Sean A Bourelle", "Ravichandran Shivanna", "Franco V A Camargo", "Soumen Ghosh", "Alexander J Gillett", "Satyaprasad P Senanayak", "Sascha Feldmann", "Lissa F L Eyre", "Arjun Ashoka", "Tim van de Goor", "Haralds Abolins", "Thomas Winkler", "Giulio Cerullo", "Richard H Friend", "Felix Deschler" ], "corpus_id": 220048242, "doc_id": "220048242", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "How Exciton Interactions Control Spin Depolarisation in Layered Hybrid Perovskites.", "venue": "Nano letters", "year": 2020 }, { "abstract": "This work demonstrates the strong excitonic magneto optic (MO) effects of magnetic circular dichroism (MCD) and Faraday rotation (FR) in nonmagnetic two dimensional (2D) organic inorganic hybrid Ruddlesden Popper perovskites (RPPs) at room temperature. Due to their strong and sharp excitonic absorption as a result of unique quantum well structures of 2D RPPs, sizeable linear excitonic MO effects of MCD and FR can be observed at room temperature under a low magnetic field <1 T) compared with their three dimensional counterpart. In addition, since the band gaps of 2D organic inorganic hybrid perovskites can be manipulated either by changing the number n of inorganic octahedral slabs per unit cell or through halide engineering, linear excitonic MO effects of 2D RPPs can be observed through the broadband spectral ranges of visible light. Our result may pave the way for the promising research field of MO and magneto optoelectronic applications based on 2D organic inorganic hybrid perovskites with facile solution processes.", "author_names": [ "Tzu-Pei Chen", "Jun-Xiao Lin", "Cheng-Chieh Lin", "Chi-Ying Lin", "W Ke", "Di-Yan Wang", "Hua-Shu Hsu", "Chia-Chun Chen", "Chun-Wei Chen" ], "corpus_id": 231954985, "doc_id": "231954985", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Strong Excitonic Magneto Optic Effects in Two Dimensional Organic Inorganic Hybrid Perovskites.", "venue": "ACS applied materials interfaces", "year": 2021 }, { "abstract": "The introduction of chirality into organic inorganic hybrid perovskites (OIHPs) is expected to achieve excellent photoelectric and nonlinear materials related to circular dichroism. Chirality dependent circular photogalvanic effect and spin transport have already been studied in OIHPs. However, chirality dependent second harmonic generation (SHG) is rarely studied in bulk single crystal of OIHPs. Due to the existence of asymmetric center and intrinsic chirality in the chiral OIHPs, the different efficiencies of SHG signal occurs when the circularly polarized light (CPL) with different phases passes through the chiral crystal, which is defined as second harmonic generation circular dichroism (SHG CD) Here, the SHG CD effect has been successfully developed in bulk single crystals chiral one dimensional (1D) R S 3 aminopiperidine]PbI 4 which crystallize in a chiral space group P 2 1 2 1 2 1 More importantly, it is the first time to distinguish CPL using chirality dependent SHG CD effect in OIHPs bulk single crystals. Furthermore, such SHG CD technology breaks through the conventional CPL detection using chiral semiconductor, thus extending the detection range to near infrared region (NIR) In this way, the anisotropy factor (g SHG CD through SHG CD signal is as high as 0.21. The results not only expand the applications of chiral OIHPs in nonlinear optics (NLO) field, but also provide a new method to distinguish the CPL in NIR.", "author_names": [ "Dongying Fu", "Jianli Xin", "Xian-Ming Zhang" ], "corpus_id": 235733443, "doc_id": "235733443", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Chirality Dependent Second order Nonlinear Optical Effects in 1D Organic Inorganic Hybrid Perovskites Bulk Single Crystal.", "venue": "Angewandte Chemie", "year": 2021 }, { "abstract": "An organic inorganic hybrid perovskite incorporating chiral organic molecules is demonstrated as a new class of chiral semiconductors. Chiral perovskites exhibit oppositely signed circular dichroism (CD) according to the S and R configurations of chiral organics. The CD signals can be also varied by changing the crystalline orientation and thickness of the chiral perovskite films.", "author_names": [ "Jihoon Ahn", "Eun Song Lee", "Jeiwan Tan", "Wooseok Yang", "Bokyung Kim", "Jooho Moon" ], "corpus_id": 98918958, "doc_id": "98918958", "n_citations": 52, "n_key_citations": 0, "score": 0, "title": "A new class of chiral semiconductors: chiral organic molecule incorporating organic inorganic hybrid perovskites", "venue": "", "year": 2017 }, { "abstract": "Chiral perovskites have emerged as a significant class of materials showing promising optoelectronic and spintronic applications. Reports of chiral perovskite ferroelectrics, however, have been scarce. In this work, we have successfully synthesized homochiral lead iodide perovskite ferroelectrics (R) N (1 phenylethyl)ethane 1,2 diaminium]PbI4 and (S) N (1 phenylethyl)ethane 1,2 diaminium]PbI4 by the chemical design of introducing a methyl group into the organic cation of the parent (N benzylethane 1,2 diaminium)PbI4. Vibrational circular dichroism spectra identify the chiral mirroring relationship. They both undergo 222F2 type paraelectric ferroelectric behavior at around 378 K coupled with clear ferroelastic domains \"ON/OFF\" switching. Besides, they exhibit an evident thermochromism with color change from orange yellow to orange red. To our knowledge, the discovery of integrated ferroelectricity, ferroelasticity and reversible thermochromism in chiral perovskites is unprecedented. This finding offers a resultful path to design chiral perovskite ferroelectrics and is of great inspiration to the discovery of multifunctional perovskite materials.", "author_names": [ "Yu-Ling Zeng", "Xue-Qin Huang", "Chao-Ran Huang", "Hua Zhang", "Fang Wang", "Zhongxia Wang" ], "corpus_id": 232078164, "doc_id": "232078164", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Unprecedented 2D Homochiral Hybrid Lead Iodide Perovskite Thermochromic Ferroelectrics with Ferroelastic Switching.", "venue": "Angewandte Chemie", "year": 2021 }, { "abstract": "The effect of chemical composition modification on the chiroptical property of chiral organic ammonium cation containing organic inorganic hybrid perovskite (chiral OIHP) is investigated. Varying the mixing ratio of bromide and iodide anions in (S or R C6H5CH2(CH3)NH3)2PbI4(1 x)Br4x modifies the bandgap of chiral OIHP, leading to a shift of the circular dichroism (CD) signal from 495 to 474 nm. However, it is also found that an abrupt crystalline structure transition occurs, and the CD signal is turned off when iodide determinant phases are transformed into the bromide determinant phase. To obtain CD in the wavelength range where the bromide determinant phase is supposed to exhibit chiroptical activity, that is, <474 nm, S or R C12H7CH2(CH3)NH3 with a larger spacer group can be adopted; thus, the CD signal can be further blue shifted to ~375 nm. Here we show that chemical composition modification of chiral OIHP affects the chiroptical properties of chiral OIHP in two ways: 1) tuning the wavelength of CD by modulating the excitonic band structure and 2) switching the CD on and off by inducing a crystalline structure change. These properties can be utilized for structural engineering of high performance chiroptical materials for spin polarized light emitting devices and polarization based optoelectronics.", "author_names": [ "Jihoon Ahn", "Sunihl Ma", "Ji-Young Kim", "Jihoon Kyhm", "Wooseok Yang", "Jung Ah Lim", "Nicholas A Kotov", "Jooho Moon" ], "corpus_id": 211099842, "doc_id": "211099842", "n_citations": 25, "n_key_citations": 0, "score": 0, "title": "Chiral 2D Organic Inorganic Hybrid Perovskite with Circular Dichroism Tunable Over Wide Wavelength Range.", "venue": "Journal of the American Chemical Society", "year": 2020 }, { "abstract": "We demonstrate theoretically that non chiral perovskite layers can exhibit circular dichroism (CD) in the absence of a magnetic field and without chiral activation by chiral molecules. The effect is shown to be due to splitting of helical excitonic states which can form in structures of orthorhombic or lower symmetry that exhibit Rashba spin effects. The selective coupling of these helical exciton states to helical light is shown to give rise to circular dichroism. Polarization dependent absorption is shown to occur due to the combined effect of Rashba splitting, in plane symmetry breaking, and the effect of the exciton momentum on its fine structure, which takes the form of Zeeman splitting in an effective magnetic field. This phenomenon, which can be considered as a manifestation of extrinsic chirality, results in significant CD with an anisotropy factor of up to 30% in orthorhombic perovskite layers under off normal, top illumination conditions, raising the possibility of its observation in non chiral perovskite structures.", "author_names": [ "Peter C Sercel", "Zeev Valy Vardeny", "Alexander L Efros" ], "corpus_id": 220280762, "doc_id": "220280762", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Circular dichroism in non chiral metal halide perovskites.", "venue": "Nanoscale", "year": 2020 } ]

[ { "abstract": "Abstract Lateral effect photodiodes sense the position of a laser beam by measuring the change of current between opposite anodes and a common cathode. They either require a bias current or the current is photogenerated. In either case, their linearity is affected by the non uniformity of the current distribution between the anodes. We here propose a bias free, lateral photo diode, which consists of a resistive layer forming an extended Schottky contact to an intrinsic semiconductor. In our sensor, the photo generated carriers do not diffuse laterally. Rather, their localization under the laser beam results in a reduction of the barrier height due to image force effect. An open circuit voltage appears between two opposite electrodes that is linear with the laser beam position. A tetra lateral configuration, with four anodes at the edges of a square shaped sensor, allows sensing in two dimensions.", "author_names": [ "Xupeng Sun", "Tianrui Zhai", "Antonio Ruotolo" ], "corpus_id": 236243766, "doc_id": "236243766", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "A bias free, lateral effect position sensor photo detector", "venue": "", "year": 2021 }, { "abstract": "Abstract Position sensitive photo detectors (PSDs) utilize the lateral photovoltaic effect to produce an electrical output that varies linearly with the position of a light spot incident on a semiconductor junction. Design, fabrication and characterization of newly developed silicon PSD, which employ the planar technology and double ion implantation with different doses, are described. Shallow and low doped p n junction is formed by boron implantation in n type silicon substrate. The position characteristics of PSD are symmetric to the zero and linear in the 80% of the active area. For a higher resistivity top layer (lower implanted dose) the sensitivity grows up and the linearity gets improved. The influence of the substrate is not substantial for the position characteristics. The response of the sensor, measured by pulsed 15 ns laser, was determined to be about 100 ns. Described PSD has been used in the construction of simple light spot rotational follower.", "author_names": [ "Ricardo C Goncalves da Silva", "Henri I Boudinov", "R R B Correia" ], "corpus_id": 9592593, "doc_id": "9592593", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Design and development of two dimensional position sensitive photo detector", "venue": "Microelectron. J.", "year": 2005 }, { "abstract": "Background: Lateral opening wedge distal femoral osteotomy (DFO) unloads a diseased lateral compartment of the knee in patients with genu valgum. To the best of our knowledge, there are no biomechanical studies investigating the effect of knee flexion on contact pressure and area after DFO. Hypothesis: As knee flexion angles increase, DFO will be less effective at unloading the lateral compartment of the knee. Study Design: Controlled laboratory study. Methods: Lateral opening wedge DFO was performed, correcting a mean of 7deg, in 10 cadaveric knees using plate fixation. Tibiofemoral contact pressure was measured in 0deg, 15deg, 30deg, 45deg, 60deg, and 75deg of knee flexion before and after osteotomy using electronic sensors. Peak contact pressure (PCP) mean contact pressure (MCP) and contact area were measured for each condition. Anatomic dissection quantified the tibiofemoral contact position on the distal femur in all degrees of flexion. Mixed effects regression analyses were used to compare the change in variables before and after osteotomy and between flexion angles. Results: One sample had to be excluded because of tibiofemoral arthritis. MCP decreased in the lateral compartment after DFO throughout all degrees of flexion (all P .05) but to the greatest extent in 0deg of flexion. When examining the percentage of MCP in the lateral compartment, this decreased after DFO at 0deg (70.4% to 40.0% P .001) 15deg (65.1% to 52.1% P .001) 30deg (60.7% to 52.0% P .003) 45deg (55.8% to 49.7% P .033) and 60deg (51.9% to 44.2% P .010) but not at 75deg (50.2% to 45.3% P .112) PCP decreased in the lateral compartment after DFO at 0deg (2.41 to 1.34 MPa; P .001) 15deg (2.50 to 1.81 MPa; P .001) 30deg (2.28 to 1.93 MPa; P .039) 45deg (2.21 to 1.73 MPa; P .005) 60deg (2.15 to 1.71 MPa; P .009) and 75deg (1.95 to 1.49 MPa; P .012) The percentage of contact area decreased in the lateral compartment in full extension (68.7% to 48.1% P .007) but not at any other degree of flexion (all P .05) Conclusion: DFO decreased lateral compartment pressure. However, it had the greatest effect in full knee extension. Clinical Relevance: DFO decreased contact pressure in the lateral compartment but more effectively decreased contact pressure in the more anterior aspects of the femoral articular cartilage.", "author_names": [ "James D Wylie", "Bastian Scheiderer", "Elifho Obopilwe", "Joshua B Baldino", "Colin Pavano", "Craig J Macken", "Ryan Bell", "Augustus D Mazzocca", "Robert A Arciero", "Florian B Imhoff" ], "corpus_id": 52881785, "doc_id": "52881785", "n_citations": 10, "n_key_citations": 1, "score": 0, "title": "The Effect of Lateral Opening Wedge Distal Femoral Varus Osteotomy on Tibiofemoral Contact Mechanics Through Knee Flexion", "venue": "The American journal of sports medicine", "year": 2018 }, { "abstract": "At present, autonomous underwater vehicles (AUVs) cannot perceive local environments in complex marine environments, where fish can obtain hydrodynamic information about the surrounding environment through a lateral line. Inspired by this biological function, an artificial lateral line system (ALLS) was built on a moving bionic carrier using the pressure sensor in this paper. When the carrier operated with different speeds in the flow field, the pressure distribution characteristics surrounding the carrier were analyzed by numerical simulation, where the effect of the flow angle between the fluid velocity direction and the carrier navigation direction was considered. The flume experiment was carried out in accordance with the simulation conditions, and the analysis results of the experiment were consistent with those in the simulation. The relationship between pressure and fluid velocity was established by a fitting method. Subsequently, the pressure difference method was investigated to establish a relationship model between the pressure difference on both sides of the carrier and the flow angle. Finally, a back propagation neural network model was used to predict the fluid velocity, flow angle, and carrier speed successfully in the unknown fluid environment. The local fluid environment perception by moving carrier carrying ALLS was studied which may promote the engineering application of the artificial lateral line in the local perception, positioning, and navigation on AUVs.", "author_names": [ "Guijie Liu", "Huanhuan Hao", "Tingting Yang", "Shuikuan Liu", "Mengmeng Wang", "Atilla Incecik", "Zhixiong Li" ], "corpus_id": 212749819, "doc_id": "212749819", "n_citations": 3, "n_key_citations": 1, "score": 0, "title": "Flow Field Perception of a Moving Carrier Based on an Artificial Lateral Line System", "venue": "Sensors", "year": 2020 }, { "abstract": "In this study, an efficient and simple designed nanohybrid created for individual and simultaneous detection of ascorbic acid (AA) dopamine (DA) and uric acid (UA) This nanohybrid is a combination of chemical reduced graphene oxide (CRGO) and redox poly(para phenylene) (Fc ac PP) modified in a lateral position with ferrrocenyl group CRGO/Fc ac PPP. The CRGO/Fc ac PPP nanohybrid demonstrated a synergistic effect resulting in a large conductivity, surface area and catalytic properties provided by the redox attached ferrocene. Moreover, this nanocomposite is able to detect individually as well as simultaneously AA, DA and UA in a co existence system with defined and separated redox peaks oxidation. The linear response ranges for AA, DA and UA, when detected simultaneously, are 0.1 10000 mM, 0.0001 1000 mM and 0.1 10000 mM, respectively, and the detection limits (S/N 3) are 0.046 mM, 0.2 nM and 0.013 mM, respectively. The proposed sensor shown satisfactory results when applied to real spiked urine samples for measuring the abnormal high or lowconcentration of AA, DA and UA in vivo.", "author_names": [ "Zouhour Hsine", "Salma Bizid", "Rym Mlika", "Helene Sauriat-Dorizon", "Ayoub Haj Said", "Hafsa Korri-Youssoufi" ], "corpus_id": 211556612, "doc_id": "211556612", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "Nanocomposite Based on Poly (para phenylene)/Chemical Reduced Graphene Oxide as a Platform for Simultaneous Detection of Ascorbic Acid, Dopamine and Uric Acid", "venue": "Sensors", "year": 2020 }, { "abstract": "Attention has been focused on the importance of anatomical tunnel placement in anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare the effect of different tunnel positions for single bundle (SB) ACL reconstruction on knee kinematics. Ten porcine knees were used for the following reconstruction techniques: three different anatomic SB [AM AM (antero medial) PL PL (postero lateral) and MID MID] (n 5 for each group) conventional SB (PL high AM) (n 5) and anatomic double bundle (DB) (n 5) Using a robotic/universal force moment sensor testing system, an 89 N anterior load (simulated KT1000 test) at 30, 60, and 90deg of knee flexion and a combined internal rotation (4 N m) and valgus (7 N m) moment (simulated pivot shift test) at 30 and 60deg were applied. Anterior tibial translation (ATT) (mm) and in situ forces (N) of reconstructed grafts were calculated. During simulated KT1000 test at 60deg of knee flexion, the PL PL had significantly lower in situ force than the intact ACL (P 0.01) In situ force of the MID MID was higher than other SB reconstructions (at 30deg: 94.8 2.5 N; at 60deg: 85.2 5.3 N; and 90deg: 66.0 8.7 N) At 30deg of knee flexion, the PL high AM had the lowest in situ values (67.1 19.3 N) At 60 and 90deg of knee flexion the PL PL had the lowest in situ values (at 60deg: 60.8 19.9 N; 90deg: 38.4 19.2 N) The MID MID and DB had no significant in situ force differences at 30 and 60deg of knee flexion. During simulated pivot shift test at 60deg of knee flexion, the PL PL and PL high AM reconstructions had a significant lower in situ force than the intact ACL (P 0.01) During simulated KT1000 test at 30, 60, and 90deg of knee flexion, the PL PL and PL high AM had significantly lower ATT than the intact ACL (P 0.01) During simulated KT1000 test at 60 and 90deg, the MID MID, AM AM, and DB had significantly lower ATT than the ACL deficient knee (P 0.01) During simulated KT1000 test at 90deg, every reconstructed knee had significantly higher ATT than the intact knee (P 0.01) In conclusion, the MID MID position provided the best stability among all anatomic SB reconstructions and more closely restored normal knee kinematics.", "author_names": [ "Yuki Kato", "Sheila Jean McNeill Ingham", "Scott Kramer", "Patrick J Smolinski", "Akiyoshi Saito", "Freddie H Fu" ], "corpus_id": 32202463, "doc_id": "32202463", "n_citations": 137, "n_key_citations": 6, "score": 0, "title": "Effect of tunnel position for anatomic single bundle ACL reconstruction on knee biomechanics in a porcine model", "venue": "Knee Surgery, Sports Traumatology, Arthroscopy", "year": 2009 }, { "abstract": "Due to the inherent misalignment variations in dynamic wireless electric vehicle (EV) charging systems, it is essential to implement effective misalignment detection and correction techniques to maximize the amount of energy received by the EV. A misalignment detection system consists of detector coils or sensors, and the corresponding detection circuitry. In this work, the design details of the auxiliary misalignment detection coils are presented. In particular, the paper investigates the effect of the number of turns of the auxiliary coils, their turn to turn spacing, and their positions relative to the edges of the secondary coil, on their lateral misalignment detection capability. Based on the conducted simulations, it is observed that increasing the number of turns as well as the turn to turn spacing of the auxiliary coils both significantly improve their misalignment detection capability by improving the resultant mutual inductance variations with lateral misalignments. Also, the optimal position of the auxiliary coils is determined to be 200 mm from both edges of the secondary coil.", "author_names": [ "Youssef Louca", "Eiman ElGhanam", "Ahmed H Osman" ], "corpus_id": 236920450, "doc_id": "236920450", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design and Modeling of Auxiliary Misalignment Detection Coils for Dynamic Wireless Electric Vehicle Charging Systems", "venue": "2021 IEEE Transportation Electrification Conference Expo (ITEC)", "year": 2021 }, { "abstract": "Total knee arthroplasty (TKA) surgery with manual instruments provides a quantitatively balanced knee in approximately 50% of cases. This study examined the effect of combining robotics technology with real time intra operative sensor feedback on the number of quantitatively balanced cases in a consecutive series of 200 robotic assisted primary TKAs. The robotics platform was used to plan the implant component position using correctable poses in extension and a manual, centrally pivoting the balancer in flexion, prior to committing to the femoral cuts. During the initial trialing, the quantitative state of balance was assessed using an instrumented tibial tray that measured the intra articular loads in the medial and lateral compartments. These sensor readings informed a number of surgical corrections, including bone recuts, soft tissue corrections, and cement adjustments. During initial trialing, a quantitatively balanced knee was achieved in only 65% of cases. After performing the relevant soft tissue corrections, bone recuts, and cement adjustments, 87% of cases ended balanced through the range of motion. Meanwhile, this resulted in a wide range of coronal alignment conditions, ranging from 6deg valgus to 9deg varus. It is therefore concluded that gaps derived from robotics navigation are not indicative for a quantitatively balanced knee, which was only consistently achieved when combining the robotics platform with real time feedback from intra operative load sensors.", "author_names": [ "Alexander C Gordon", "Michael A Conditt", "Matthias A Verstraete" ], "corpus_id": 231623698, "doc_id": "231623698", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Achieving a Balanced Knee in Robotic TKA", "venue": "Sensors", "year": 2021 }, { "abstract": "An ideal microcalorimeter is characterized by a constant energy resolution across the sensor's dynamic range. Any dependence of pulse shape on the position within the absorber where an event occurs leads to a degradation in resolution that is linear with event's energy (excess broadening) In this paper we present a numerical simulation that was developed to model the variation in pulse shape with position based on the thermal conductivity within the absorber and between the absorber, sensor, and heat bath, for arbitrarily shaped absorbers and sensors. All the parameters required for the simulation can be measured from actual devices. We describe how the thermal conductivity of the absorber material is determined by comparing the results of this model with data taken from a position sensitive detector in which any position dependent effect is purposely emphasized by constructing a long, narrow absorber that is readout by sensors on both ends. Finally, we present the implications for excess broadening given the measured parameters of our X ray microcalorimeters.", "author_names": [ "Tarek Saab", "Enectali Figueroa-Feliciano", "Naoko Iyomoto", "B D Herbert", "S R Bandler", "J A Chervenak", "Fred M Finkbeiner", "Richard Lloyd Kelley", "Caroline A Kilbourne", "Frederick S Porter", "John E Sadleir" ], "corpus_id": 121573960, "doc_id": "121573960", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Determination of lateral diffusivity in single pixel X ray absorbers with implications for position dependent excess broadening", "venue": "", "year": 2006 }, { "abstract": "Active beam stabilization is decisive in numerous applications such as free space optical (FSO) communication, military, biomedical etc. FSO communication receivers require very precise and stable pointing mechanism to maintain optimal operation. Any vibration, micro positional drift can affect efficiency and performance of active optical component and introduce an error which propagates throughout optical line [1] Beam wandering and atmospheric effect also causes the contravention of FSO communication. In this paper we have demonstrated active beam stabilization technique using fast steering mirror (FSM) and Quad detector in closed loop for FSO receiver in laboratory. The quad detector senses the error voltage according to the position of laser beacon. The error voltage is fed to FSM controller which is used in an external sensor feedback control mode with position feedback from quad photo detector and the FSM rectifies in the desired position.", "author_names": [ "Koushik Basak", "R K Bahl", "Payal Sharma", "A Banik" ], "corpus_id": 110037888, "doc_id": "110037888", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Demonstration of Active Laser Beam Stabilization in Closed Loop for Free Space Optical Receiver", "venue": "", "year": 2015 } ]

[ { "abstract": "Ferroelectric Rashba semiconductors (FERSCs) have recently attracted intensive attention due to their giant bulk Rashba parameter, aR, which results in a locking between the spin degrees of freedom and the switchable electric polarization. However, the integration of FERSCs into microelectronic devices has provoked questions concerning whether the Rashba effect can persist when the material thickness is reduced to several nanometers. Here we find that aR can keep a large value of 2.12 eV A in the 5.0 nm thick GeTe film. The behavior of aR with thickness can be expressed by the scaling law and provides a 3D thickness limit of the bulk Rashba effect, dc 2.1 0.5 nm. Finally, we find that the thickness can modify the Berry curvature as well, which influences the polarization and consequently alters the aR. Our results give insight into understanding the factors influencing aR in FERSCs and pave a novel route for designing Rashba type quantum materials.", "author_names": [ "Xu Yang", "Xiaomei Li", "Yang Li", "Yan Su Li", "Rui Sun", "Jia-nan Liu", "Xuedong Bai", "Na Li", "Zong-Kai Xie", "Lei Su", "Zi-zhao Gong", "Xiang-qun Zhang", "Wei He", "Zhaohua Cheng" ], "corpus_id": 227250921, "doc_id": "227250921", "n_citations": 1, "n_key_citations": 0, "score": 2, "title": "Three Dimensional Limit of Bulk Rashba Effect in Ferroelectric Semiconductor GeTe.", "venue": "Nano letters", "year": 2020 }, { "abstract": "We study the optoelectronic properties of a type II heterojunction (HJ) comprising a monolayer of the transition metal dichalcogenide (TMDC) WS2, and a thin film of the organic semiconductor, 3,4,9,10 perylene tetracarboxylic dianhydride (PTCDA) Both theoretical and experimental investigations of the HJ indicate that Frenkel states in the organic layer and two dimensional Wannier Mott states in the TMDC dissociate to form hybrid charge transfer excitons at the interface that subsequently dissociate into free charges that are collected at opposing electrodes. A photodiode employing the HJ achieves a peak external quantum efficiency of 1.8 0.2% at a wavelength of 430 10 nm, corresponding to an internal quantum efficiency (IQE) as high as 11 1% in these ultrathin devices. The photoluminescence spectra of PTCDA and PTCDA/WS2 thin films show that excitons in the WS2 have a quenching rate that is approximately seven times higher than in PTCDA. This difference leads to strong wavelength dependence in IQE.", "author_names": [ "Xiao Liu", "Jie Gu", "Kan Ding", "Dejiu Fan", "Xiaoer Hu", "Yu-wen Tseng", "Yi-Hsien Lee", "Vinod M Menon", "Stephen R Forrest" ], "corpus_id": 35868539, "doc_id": "35868539", "n_citations": 53, "n_key_citations": 0, "score": 0, "title": "Photoresponse of an Organic Semiconductor/Two Dimensional Transition Metal Dichalcogenide Heterojunction.", "venue": "Nano letters", "year": 2017 }, { "abstract": "The epitaxial growth of multifunctional oxides on semiconductors has opened a pathway to introduce new functionalities to semiconductor device technologies. In particular, the integration of gate materials that enable nonvolatile or hysteretic functionality in field effect transistors could lead to device technologies that consume less power or allow for novel modalities in computing. Here we present electrical characterization of ultrathin single crystalline SrZrxTi1 xO3 (x 0.7) films epitaxially grown on a high mobility semiconductor, Ge. Epitaxial films of SrZrxTi1 xO3 exhibit relaxor behavior, characterized by a hysteretic polarization that can modulate the surface potential of Ge. We find that gate layers as thin as 5 nm corresponding to an equivalent oxide thickness of just 1.0 nm exhibit a ~2 V hysteretic window in the capacitance voltage characteristics. The development of hysteretic metal oxide semiconductor capacitors with nanoscale gate thicknesses opens new vistas for nanoelectronic devices.", "author_names": [ "Reza Maleki Moghadam", "Zhiyong Xiao", "Kamyar Ahmadi-Majlan", "E D Grimley", "Mark E Bowden", "Phuong-Vu Ong", "Scott A Chambers", "J M Lebeau", "Xia Hong", "Peter V Sushko", "Joseph H Ngai" ], "corpus_id": 20357569, "doc_id": "20357569", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "An Ultrathin Single Crystalline Relaxor Ferroelectric Integrated on a High Mobility Semiconductor.", "venue": "Nano letters", "year": 2017 }, { "abstract": "Graphene heterostructures in which graphene is combined with semiconductors or other layered 2D materials are of considerable interest, as a new class of electronic devices has been realized. Here we propose a technology platform based on graphene thin film semiconductor metal (GSM) junctions, which can be applied to large scale and power efficient electronics compatible with a variety of substrates. We demonstrate wafer scale integration of vertical field effect transistors (VFETs) based on graphene In Ga Zn O (IGZO) metal asymmetric junctions on a transparent 150 x 150 mm(2) glass. In this system, a triangular energy barrier between the graphene and metal is designed by selecting a metal with a proper work function. We obtain a maximum current on/off ratio (Ion/Ioff) up to 10(6) with an average of 3010 over 2000 devices under ambient conditions. For low power logic applications, an inverter that combines complementary n type (IGZO) and p type (Ge) devices is demonstrated to operate at a bias of only 0.5 V.", "author_names": [ "Jinseong Heo", "Kyung-Eun Byun", "Jaeho Lee", "Hyun-Jong Chung", "Sanghun Jeon", "Seongjun Park", "Sungwoo Hwang" ], "corpus_id": 29399007, "doc_id": "29399007", "n_citations": 57, "n_key_citations": 0, "score": 0, "title": "Graphene and thin film semiconductor heterojunction transistors integrated on wafer scale for low power electronics.", "venue": "Nano letters", "year": 2013 }, { "abstract": "Low temperature electrostatic force microscopy (EFM) is used to probe unconventional domain walls in the improper ferroelectric semiconductor Er0.99Ca0.01MnO3 down to cryogenic temperatures. The low temperature EFM maps reveal pronounced electric far fields generated by partially uncompensated domain wall bound charges. Positively and negatively charged walls display qualitatively different fields as a function of temperature, which we explain based on different screening mechanisms and the corresponding relaxation time of the mobile carriers. Our results demonstrate domain walls in improper ferroelectrics as a unique example of natural interfaces that are stable against the emergence of electrically uncompensated bound charges. The outstanding robustness of improper ferroelectric domain walls in conjunction with their electronic versatility brings us an important step closer to the development of durable and ultrasmall electronic components for next generation nanotechnology.", "author_names": [ "Peggy Schoenherr", "Konstantin Shapovalov", "Jakob Schaab", "Zewu Yan", "Edith D Bourret", "Mario Hentschel", "Massimiliano Stengel", "Manfred Fiebig", "Andres Cano", "Dennis Meier" ], "corpus_id": 73434530, "doc_id": "73434530", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Observation of Uncompensated Bound Charges at Improper Ferroelectric Domain Walls.", "venue": "Nano letters", "year": 2019 }, { "abstract": "Crystalline oxide ferroelectric tunnel junctions enable persistent encoding of information in electric polarization, featuring nondestructive readout and scalability that can exceed current commercial high speed, nonvolatile ferroelectric memories. However, the well established fabrication of epitaxial devices on oxide substrates is difficult to adapt to silicon substrates for integration into complementary metal oxide semiconductor electronics. In this work, we report ferroelectric tunnel junctions based on 2.8 nm thick BaTiO3 films grown epitaxially on SrTiO3 growth substrates, released, and relaminated onto silicon. The performance of the transferred devices is comparable to devices characterized on the oxide substrate, suggesting a viable route toward next generation nonvolatile memories broadly integrable with different materials platforms.", "author_names": [ "Di Lu", "S Crossley", "Ruijuan Xu", "Yasuyuki Hikita", "Harold Y Hwang" ], "corpus_id": 206750535, "doc_id": "206750535", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "Freestanding Oxide Ferroelectric Tunnel Junction Memories Transferred onto Silicon.", "venue": "Nano letters", "year": 2019 }, { "abstract": "Enriching the functionality of ferroelectric materials with visible light sensitivity and multiaxial switching capability would open up new opportunities for their applications in advanced information storage with diverse signal manipulation functions. We report experimental observations of robust intralayer ferroelectricity in two dimensional (2D) van der Waals layered a In2Se3 ultrathin flakes at room temperature. Distinct from other 2D and conventional ferroelectrics, In2Se3 exhibits intrinsically intercorrelated out of plane and in plane polarization, where the reversal of the out of plane polarization by a vertical electric field also induces the rotation of the in plane polarization. On the basis of the in plane switchable diode effect and the narrow bandgap ~1.3 eV) of ferroelectric In2Se3, a prototypical nonvolatile memory device, which can be manipulated both by electric field and visible light illumination, is demonstrated for advancing data storage technologies.", "author_names": [ "Chaojie Cui", "Weijin Hu", "Xingxu Yan", "Christopher Addiego", "Wenpei Gao", "Yaoling Wang", "Zhe Wang", "Linze Li", "Yingchun Cheng", "Peng Li", "Xixiang Zhang", "Husam N Alshareef", "Tom Wu", "Wenguang Zhu", "Xiaoqing Pan", "Lain-Jong Li" ], "corpus_id": 206745952, "doc_id": "206745952", "n_citations": 200, "n_key_citations": 2, "score": 0, "title": "Intercorrelated In Plane and Out of Plane Ferroelectricity in Ultrathin Two Dimensional Layered Semiconductor In2Se3.", "venue": "Nano letters", "year": 2018 }, { "abstract": "For advanced device applications, increasing the compositional abruptness of axial heterostructured and modulation doped nanowires is critical for optimizing performance. For nanowires grown from metal catalysts, the transition region width is dictated by the solute solubility within the catalyst. For example, as a result of the relatively high solubility of Si and Ge in liquid Au for vapor liquid solid (VLS) grown nanowires, the transition region width between an axial Si Ge heterojunction is typically on the order of the nanowire diameter. When the solute solubility in the catalyst is lowered, the heterojunction width can be made sharper. Here we show for the first time the systematic increase in interface sharpness between axial Ge Si heterojunction nanowires grown by the VLS growth method using a Au Ga alloy catalyst. Through in situ tailoring of the catalyst composition using trimethylgallium, the Ge Si heterojunction width is systematically controlled by tuning the semiconductor solubility within a metal Au Ga alloy catalyst. The present approach of alloying to control solute solubilities in the liquid catalyst may be extended to increasing the sharpness of axial dopant profiles, for example, in Si Ge pn heterojunction nanowires which is important for such applications as nanowire tunnel field effect transistors or in Si pn junction nanowires.", "author_names": [ "Daniel E Perea", "Nan Li", "Robert M Dickerson", "Amit Misra", "Samuel T Picraux" ], "corpus_id": 21248009, "doc_id": "21248009", "n_citations": 88, "n_key_citations": 2, "score": 0, "title": "Controlling heterojunction abruptness in VLS grown semiconductor nanowires via in situ catalyst alloying.", "venue": "Nano letters", "year": 2011 }, { "abstract": "Organic semiconductor insulator blend films are widely explored for high performance electronic devices enabled by unique phase separation and self assembly phenomena at key device interfaces. Here we report the first demonstration of high performance hybrid diodes based on p n junctions formed by a p type poly(3 hexylthiophene) (P3HT) poly(methyl methacrylate) (PMMA) blend and n type indium gallium zinc oxide (IGZO) The thin film morphology, microstructure, and vertical phase separation behavior of the P3HT films with varying contents of PMMA are systematically analyzed. Microstructural and charge transport evaluation indicates that the polymer insulator component positively impacts the morphology, molecular orientation, and effective conjugation length of the P3HT films, thereby enhancing the heterojunction performance. Furthermore, the data suggest that PMMA phase segregation creates a continuous nanoscopic interlayer between the P3HT and IGZO layers, playing an important role in enhancing diode performance. Thus, the diode based on an optimal P3HT PMMA blend exhibits a remarkable 10 fold increase in forward current versus that of a neat P3HT diode, yielding an ideality factor value as low as 2.5, and a moderate effective barrier height with an excellent rectification ratio. These results offer a new approach to simplified manufacturing of low cost, large area hybrid inorganic organic electronics technologies.", "author_names": [ "Xinan Zhang", "Binghao Wang", "Wei Huang", "G Wang", "Weigang Zhu", "Zhi Wang", "Weifeng Zhang", "Antonio F Facchetti", "Tobin J Marks" ], "corpus_id": 54523033, "doc_id": "54523033", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Oxide Polymer Heterojunction Diodes with a Nanoscopic Phase Separated Insulating Layer.", "venue": "Nano letters", "year": 2019 }, { "abstract": "An important factor in the performance of photoelectrochemical water splitting is the band edge alignment of the photoelectrodes for efficient transport and transfer of photogenerated carriers. Many studies for improving charge transfer ability between the electrode and the electrolyte have been reported, while research to improve charge transfer at the interface of the photoactive semiconductor and the conducting substrate is largely lacking. Here, we demonstrate that the water splitting performance of an oxide heterostructured photoelectrode can be increased 6 fold by inserting an atomically thin polar LaAlO3 interlayer compared with that of an oxide heterostructure without an insertion to modify interfacial band offsets. The electrically lowered Schottky barrier is driven by the atomically thin layer, and the charge transfer resistance between the oxides is reduced by up to 2 orders of magnitude upon insertion of LaAlO3, a wide gap (5.6 eV) insulator. We show that the critical thickness of the polar layer for enhancing the charge transfer is 3 unit cells. The dipole moment from the polar sheets of LaAlO3 introduces an internal electric field, which modifies the effective band offsets in the device. This work serves as a proof of concept that photoelectrochemical performance can be improved by manipulating the band offsets of the heterostructure interface, suggesting a new design strategy for heterostructured water splitting photoelectrodes.", "author_names": [ "Taemin Kim", "Min-Ju Choi", "Tae Hyung Lee", "Woon Yong Sohn", "Ho Won Jang" ], "corpus_id": 157057209, "doc_id": "157057209", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Tailoring of Interfacial Band Offsets by an Atomically Thin Polar Insulating Layer To Enhance the Water Splitting Performance of Oxide Heterojunction Photoanodes.", "venue": "Nano letters", "year": 2019 } ]

[ { "abstract": "Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed are comprised of organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recent advances in the control of the sizes and shapes of inorganic nanocrystals allow for the formation of a broad class of new inorganic liquid crystals. Here we show the formation of liquid crystalline phases of CdSe semiconductor nanorods. These new liquid crystalline phases may have great importance for both application and fundamental study.", "author_names": [ "L Li", "Joost Walda", "Liberato Manna", "A Paul Alivisatos" ], "corpus_id": 135769112, "doc_id": "135769112", "n_citations": 221, "n_key_citations": 1, "score": 1, "title": "Semiconductor Nanorod Liquid Crystals", "venue": "", "year": 2002 }, { "abstract": "", "author_names": [ "L Li", "A Paul Alivisatos" ], "corpus_id": 41288570, "doc_id": "41288570", "n_citations": 176, "n_key_citations": 1, "score": 0, "title": "Semiconductor nanorod liquid crystals and their assembly on a substrate", "venue": "", "year": 2003 }, { "abstract": "Abstract In this project we developed a new type of material system for use in opto electronic applications. It consists of an array of nanorods. The nanorods are quantum semiconductor structures with high fluorescence quantum yields, and with their bandgap emission energy controlled by the diameter of the rod. These quantum rods are coated with a monolayer of organic surfactant which renders them highly soluble in organic liquids. We demonstrated a method by which these nanorods can be deposited from solution in the presence of an electric field, such that the nanorods are oriented perpendicularly to the substrate.", "author_names": [ "A Paul Alivisatos" ], "corpus_id": 91450142, "doc_id": "91450142", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Electro Optic Materials Based Upon Inorganic Semiconductor Nanorod Liquid Crystals", "venue": "", "year": 2006 }, { "abstract": "Photonic crystals (PCs) have many applications in order to control light wave propagation. A novel type of two dimensional anisotropic PC is investigated band gap and optical properties as a hollow semiconductor nanorod with nematicliquid crystals (LC) The PC structure composed of an anisotropic nematicLC in semiconductor square hollow nanorod is designed using the plane wave expansion (PWE) method and finite difference time domain (FDTD) method. It has been used 5CB (4 pentyl 4` cyanobiphenyl) as LC core, and Tellurium (Te) as square hollow nanorod material.The PC with hollow Tenanorod with nematicLC is compared with the PC with solid Tenanorodand the PC with hollow Tenanorod.", "author_names": [ "Filiz Karaomerlioglu", "Sevket Simsek", "Amirullah M Mamedov", "Ekmel Ozbay" ], "corpus_id": 108950160, "doc_id": "108950160", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "2D Anisotropic Photonic Crystals of Hollow Semiconductor Nanorod with Liquid Crystals", "venue": "", "year": 2013 }, { "abstract": "We studied the electro optical property and photorefractive effects in a semiconductor CdSe nanorod doped neamtic liquid crystal [NLC] system. The nonlinear index coefficient is measured to be n2=2.05x10 2cm2/W, which is 10 times larger than that of an equivalent pure liquid crystal system. Electro optical switching investigation shows that the Freedericksz transition voltage of this system is also noticeably lower than that of un doped NLC. These enhanced electro and nonlinear optical properties are attributed to the photoconductivity of CdSe nanorods and the enlarged electric conductivity and dielectric anisotropies of the doped system. An AC field assisted photorefractive effect in CdSe nanorod doped liquid crystal system has also been studied.", "author_names": [ "Y Williams", "Kan Chan", "Jae-Hong Park", "Iam-choon Khoo", "B A Lewis", "Thomas E Mallouk" ], "corpus_id": 120970529, "doc_id": "120970529", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Electro optical and nonlinear optical properties of semiconductor nanorod doped liquid crystals", "venue": "SPIE Optics Photonics", "year": 2005 }, { "abstract": "Monolayer WS2 has interesting properties as a direct bandgap semiconductor, photocatalyst, and electrocatalyst, but it is still a significant challenge to prepare this material in colloidal form by liquid phase exfoliation (LPE) Here, we report the preparation of 1 2 layer semiconducting WS2 nanosheets in a yield of 18 22 wt by a modified LPE method that involves preintercalation with substoichometric quantities of n butyllithium. The exfoliated WS2 nanosheeets are n type, have a bandgap of ~1.78 eV, and act as a cocatalyst with CdS nanorods in photocatalytic hydrogen evolution using lactate as a sacrificial electron donor. Up to a 26 fold increase in H2 evolution rate was observed with WS2/CdS hybrids compared with their pure CdS counterpart, and an absorbed photon quantum yield (AQE) of >60% was measured with the optimized photocatalyst.", "author_names": [ "Danyun Xu", "Pengtao Xu", "Yuanzhi Zhu", "Wenchao Peng", "Yulian Li", "Guoliang Zhang", "Fengbao Zhang", "Thomas E Mallouk", "Xiaobin Fan" ], "corpus_id": 206474143, "doc_id": "206474143", "n_citations": 63, "n_key_citations": 0, "score": 0, "title": "High Yield Exfoliation of WS2 Crystals into 1 2 Layer Semiconducting Nanosheets and Efficient Photocatalytic Hydrogen Evolution from WS2/CdS Nanorod Composites.", "venue": "ACS applied materials interfaces", "year": 2018 }, { "abstract": "Photoalignment technology provides high alignment quality with an exceptional control over the local director of liquid crystals. Because of the reorientation ability of sulfonic azo dye molecules, they offer high azimuthal and polar anchoring energy with a low pretilt angle for the orientation of liquid crystals and liquid crystal composites. In this work, we make use of this approach to align thin film composites of light emitting semiconductor nanorods dispersed in a liquid crystal polymer into both one dimensional and two dimensional microscale patterns. After unidirectional alignment, the patterns are fabricated by a second irradiation with different polarization azimuth and the employment of a photomask. Fluorescence micrographs reveal the nanorod pattern alignment in domain sizes down to 2 mm. Apart from demonstrating the possibility of controlling the orientation of anisotropic nanocrystals with strongly polarized emission on microscopic scale, our results are promising for the fabrication of complex nanostructures for photonic applications.", "author_names": [ "Julian Schneider", "Wanlong Zhang", "Abhishek K Srivastava", "Vladimir G Chigrinov", "H S Kwok", "Andrey L Rogach" ], "corpus_id": 149326, "doc_id": "149326", "n_citations": 45, "n_key_citations": 1, "score": 0, "title": "Photoinduced Micropattern Alignment of Semiconductor Nanorods with Polarized Emission in a Liquid Crystal Polymer Matrix.", "venue": "Nano letters", "year": 2017 }, { "abstract": "This report describes how doping liquid crystals (LC) with rod like hexagonal semiconductor nanoprisms alters the dielectric and elastic properties of the composites as compared with a pristine nematic liquid crystal (NLC) Cadmium sulfide nanorods were synthesized via the solvothermal process and blended with a NLC. Nanorods were highly miscible with NLC and produced a topological defect free texture up to a certain limit. A good dark state was achieved during the homeotropic configuration of the cell within that limit. Appreciable changes in splay and bend elastic constants of the LCs were observed after blending with nanorods. Long range order was established in the hybrid system, and consequently the anisotropy was increased. The threshold voltage decreased dramatically by ?31% Dielectric study revealed a high frequency mode, which might be due to anchoring of the LC with nanorods.", "author_names": [ "Prasenjit Nayek", "Santanu Karan", "Sudarshan Kundu", "Seung Hee Lee", "Sudeshna Das Gupta", "Soumen Kumar Roy", "Subir Kumar Roy" ], "corpus_id": 120549710, "doc_id": "120549710", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Effect of cadmium sulfide nanorod content on Freedericksz threshold voltage, splay and bend elastic constants in liquid crystal nanocomposites", "venue": "", "year": 2012 }, { "abstract": "ZnO nanorod polymer hybrids (i.e. ZnO nanorods coated with a block copolymer with a short anchor block (dopamine) and a longer solubilizing block of polystyrene (PS) form liquid crystalline (LC) phases if they are dispersed at high concentration e.g. in a PS oligomer matrix. Due to the high mobility of the low T(g) matrix the nanorod polymer hybrids show a switching behavior under an applied AC electric field. Hence, the orientation of the nanorod mesogens can be changed from planar (parallel to the substrate) to homeotropic (perpendicular) in full analogy to the switching of low molecular liquid crystals in an electric field. Dielectric measurements show that such a switching is mainly due to the cooperative LC behavior, because the rods themselves exhibit only a very small effective dipole moment. The process can be investigated by polarizing microscopy. SEM images show the orientations of the individual nanorods, which correspond to the Fredericks transition well known for liquid crystals aligned in an electric field. This was the first time such a transition could be visualized by electron microscopy due to the large nanorod mesogens. The observation is interesting to orient nanorods perpendicular to an electrode and can help to improve optoelectronic devices.", "author_names": [ "Matthias Zorn", "Muhammad Nawaz Tahir", "Bjorn Bergmann", "Wolfgang Tremel", "Christos Grigoriadis", "George Floudas", "Rudolf Zentel" ], "corpus_id": 206225687, "doc_id": "206225687", "n_citations": 34, "n_key_citations": 0, "score": 0, "title": "Orientation and Dynamics of ZnO Nanorod Liquid Crystals in Electric Fields.", "venue": "Macromolecular rapid communications", "year": 2010 }, { "abstract": "Biominerals such as bones and teeth have elaborate nanostructures composed of aligned anisotropic hydroxyapatite (HAp) nanocrystals, which results in excellent mechanical properties. Construction of such ordered structures of HAp nanocrystals in synthetic materials is challenging. Recently, we reported that HAp nanorod based colloidal liquid crystals could be obtained. In the present study, the static structure and dynamics of liquid crystalline (LC) colloidal dispersions of HAp nanorods are investigated by using small angle X ray scattering (SAXS) and X ray photon correlation spectroscopy (XPCS) The SAXS results reveal that the interparticle distance decreases with increasing HAp concentration, phHAp, and the decrease of the interparticle distance for the short axis direction is significantly smaller in the LC phase than the interparticle distance in the isotropic phase. In the dynamical studies of the LC phase using XPCS, we observe the diffusive motion of the HAp colloids, with the diffusion coefficient being dependent on the wave number. The diffusive motion slows down with increasing phHAp. We observe anisotropic dynamics after long term storage (160 days after sealing) whereas only isotropic dynamics are observed in the initial XPCS measurements after short term storage (14 days after sealing) Moreover, we have found that the dynamics slows down with increasing storage time.", "author_names": [ "Taiki Hoshino", "Masanari Nakayama", "So Fujinami", "Tomotaka Nakatani", "Yoshiki Kohmura", "Takashi Kato" ], "corpus_id": 73468597, "doc_id": "73468597", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Static structure and dynamical behavior of colloidal liquid crystals consisting of hydroxyapatite based nanorod hybrids.", "venue": "Soft matter", "year": 2019 } ]

[ { "abstract": "Writing Conductive Lines with Hot Tips The interface within devices between conductors, semiconductors, and insulators is usually created by stacking patterned layers of different materials. For flexible electronics, it can be advantageous to avoid this architectural constraint. Graphene oxide, formed by chemical exfoliation of graphite, can be reduced to a more conductive form using chemical reductants. Wei et al. (p. 1373) now show that layers of graphene oxide can also be reduced using a hot atomic force microscope tip to create materials comparable to those of organic conductors. This process can create patterned regions (down to 12 nanometers in width) that differ in conductivity by up to four orders of magnitude. Conducting regions can be drawn on graphene oxide sheets with a heated atomic force microscope tip. The reduced form of graphene oxide (GO) is an attractive alternative to graphene for producing large scale flexible conductors and for creating devices that require an electronic gap. We report on a means to tune the topographical and electrical properties of reduced GO (rGO) with nanoscopic resolution by local thermal reduction of GO with a heated atomic force microscope tip. The rGO regions are up to four orders of magnitude more conductive than pristine GO. No sign of tip wear or sample tearing was observed. Variably conductive nanoribbons with dimensions down to 12 nanometers could be produced in oxidized epitaxial graphene films in a single step that is clean, rapid, and reliable.", "author_names": [ "Zhongqing Wei", "Debing Wang", "Suenne Kim", "Soo-Young Kim", "Michael K Yakes", "Arnaldo R Laracuente", "Zhenting Dai", "Seth R Marder", "Claire Berger", "William P King", "Walt A de Heer", "Paul E Sheehan", "Elisa Riedo" ], "corpus_id": 9672782, "doc_id": "9672782", "n_citations": 610, "n_key_citations": 11, "score": 0, "title": "Nanoscale Tunable Reduction of Graphene Oxide for Graphene Electronics", "venue": "Science", "year": 2010 }, { "abstract": "The thermal and flammability properties of polypropylene/multi walled carbon nanotube, (PP/MWNT) nanocomposites were measured with the MWNT content varied from 0.5 to 4% by mass. Dispersion of MWNTs in these nanocomposites was characterized by SEM and optical microscopy. Flammability properties were measured with a cone calorimeter in air and a gasification device in a nitrogen atmosphere. A significant reduction in the peak heat release rate was observed; the greatest reduction was obtained with a MWNT content of 1% by mass. Since the addition of carbon black powder to PP did not reduce the heat release rate as much as with the PP/MWNT nanocomposites, the size and shape of carbon particles appear to be important for effectively reducing the flammability of PP. The radiative ignition delay time of a nanocomposite having less than 2% by mass of MWNT was shorter than that of PP due to an increase in the radiation in depth absorption coefficient by the addition of carbon nanotubes. The effects of residual iron particles and of defects in the MWNTs on the heat release rate of the nanocomposite were not significant. The flame retardant performance was achieved through the formation of a relatively uniform network structured floccule layer covering the entire sample surface without any cracks or gaps. This layer re emitted much of the incident radiation back into the gas phase from its hot surface and thus reduced the transmitted flux to the receding PP layers below it, slowing the PP pyrolysis rate. To gain insight into this phenomena, thermal conductivities of the nanocomposites were measured as a function of temperature while the thermal conductivity of the nanocomposite increases with an increase in MWNT content, the effect being particularly large above 160 degC, this increase is not as dramatic as the increase in electrical conductivity, however.", "author_names": [ "Takashi Kashiwagi", "Eric A Grulke", "Jenny Hilding", "Katrina M Groth", "Richard H Harris", "Kathryn M Butler", "John R Shields", "Seman B Kharchenko", "Jack F Douglas" ], "corpus_id": 56008063, "doc_id": "56008063", "n_citations": 555, "n_key_citations": 6, "score": 0, "title": "Thermal and flammability properties of polypropylene/carbon nanotube nanocomposites", "venue": "", "year": 2004 }, { "abstract": "Abstract In the large field of nanotechnology, polymer matrix based nanocomposites have become a prominent area of current research and development. Exfoliated clay based nanocomposites have dominated the polymer literature but there are a large number of other significant areas of current and emerging interest. This review will detail the technology involved with exfoliated clay based nanocomposites and also include other important areas including barrier properties, flammability resistance, biomedical applications, electrical/electronic/optoelectronic applications and fuel cell interests. The important question of the \"nano effect\" of nanoparticle or fiber inclusion relative to their larger scale counterparts is addressed relative to crystallization and glass transition behavior. Of course, other polymer (and composite) based properties derive benefits from nanoscale filler or fiber addition and these are addressed.", "author_names": [ "Donald R Paul", "Lloyd Mahlon Robeson" ], "corpus_id": 73599695, "doc_id": "73599695", "n_citations": 2634, "n_key_citations": 47, "score": 0, "title": "Polymer nanotechnology: Nanocomposites", "venue": "", "year": 2008 }, { "abstract": "It is demonstrated from stress induced Raman bands shifts that stress can be transferred from a polymer matrix to a graphene monolayer (see image) in a model nanocomposite. It is shown further that the behavior can be modeled using continuum mechanics and that the interface between the graphene and the polymer breaks down at a shear stress of the order of 2 MPa.", "author_names": [ "Lei Gong", "Ian A Kinloch", "Robert J Young", "Ibtsam Riaz", "Rashid Jalil", "Kostya S Novoselov" ], "corpus_id": 7444626, "doc_id": "7444626", "n_citations": 462, "n_key_citations": 18, "score": 0, "title": "Interfacial stress transfer in a graphene monolayer nanocomposite.", "venue": "Advanced materials", "year": 2010 }, { "abstract": "Graphene sheets one atom thick two dimensional layers of sp2 bonded carbon are predicted to have a range of unusual properties. Their thermal conductivity and mechanical stiffness may rival the remarkable in plane values for graphite ~3,000 W m 1 K 1 and 1,060 GPa, respectively) their fracture strength should be comparable to that of carbon nanotubes for similar types of defects; and recent studies have shown that individual graphene sheets have extraordinary electronic transport properties. One possible route to harnessing these properties for applications would be to incorporate graphene sheets in a composite material. The manufacturing of such composites requires not only that graphene sheets be produced on a sufficient scale but that they also be incorporated, and homogeneously distributed, into various matrices. Graphite, inexpensive and available in large quantity, unfortunately does not readily exfoliate to yield individual graphene sheets. Here we present a general approach for the preparation of graphene polymer composites via complete exfoliation of graphite and molecular level dispersion of individual, chemically modified graphene sheets within polymer hosts. A polystyrene graphene composite formed by this route exhibits a percolation threshold of ~0.1 volume per cent for room temperature electrical conductivity, the lowest reported value for any carbon based composite except for those involving carbon nanotubes; at only 1 volume per cent, this composite has a conductivity of ~0.1 S m 1, sufficient for many electrical applications. Our bottom up chemical approach of tuning the graphene sheet properties provides a path to a broad new class of graphene based materials and their use in a variety of applications.", "author_names": [ "Sasha Z Stankovich", "Dmitriy A Dikin", "Geoffrey H B Dommett", "K Kohlhaas", "Eric J Zimney", "Eric A Stach", "Richard D Piner", "SonBinh T Nguyen", "Rodney S Ruoff" ], "corpus_id": 37536, "doc_id": "37536", "n_citations": 10435, "n_key_citations": 74, "score": 0, "title": "Graphene based composite materials", "venue": "Nature", "year": 2006 }, { "abstract": "This paper reviews recent advances in the modification of graphene and the fabrication of graphene based polymer nanocomposites. Recently, graphene has attracted both academic and industrial interest because it can produce a dramatic improvement in properties at very low filler content. The modification of graphene/graphene oxide and the utilization of these materials in the fabrication of nanocomposites with different polymer matrixes have been explored. Different organic polymers have been used to fabricate graphene filled polymer nanocomposites by a range of methods. In the case of modified graphene based polymer nanocomposites, the percolation threshold can be achieved at a very lower filler loading. Herein, the structure, preparation and properties of polymer/graphene nanocomposites are discussed in general along with detailed examples drawn from the scientific literature.", "author_names": [ "Tapas Kuilla", "Sambhu Bhadra", "Da-hu Yao", "Nam Hoon Kim", "Saswata Bose", "Joong Hee Lee" ], "corpus_id": 137548823, "doc_id": "137548823", "n_citations": 2698, "n_key_citations": 46, "score": 0, "title": "Recent advances in graphene based polymer composites", "venue": "", "year": 2010 }, { "abstract": "Graphene nanosheets were prepared by complete oxidation of pristine graphite followed by thermal exfoliation and reduction. Polyethylene terephthalate (PET)/graphene nanocomposites were prepared by melt compounding. Transmission electron microscopy observation indicated that graphene nanosheets exhibited a uniform dispersion in PET matrix. The incorporation of graphene greatly improved the electrical conductivity of PET, resulting in a sharp transition from electrical insulator to semiconductor with a low percolation threshold of 0.47 vol. A high electrical conductivity of 2.11 S/m was achieved with only 3.0 vol. of graphene. The low percolation threshold and superior electrical conductivity are attributed to the high aspect ratio, large specific surface area and uniform dispersion of the graphene nanosheets in PET matrix.", "author_names": [ "Haobin Zhang", "Wenge Zheng", "Qing Yan", "Yong Yang", "Jiwen Wang", "Zhao-Hui Lu", "Guoying Ji", "Zhong-Zhen Yu" ], "corpus_id": 137457265, "doc_id": "137457265", "n_citations": 583, "n_key_citations": 5, "score": 0, "title": "Electrically conductive polyethylene terephthalate/graphene nanocomposites prepared by melt compounding", "venue": "", "year": 2010 }, { "abstract": "Graphene oxide (GO) derived from oxidation of natural graphite contains many active groups that can interact with a great variety of polar moieties. In this work, polypropylene (PP)/graphene oxide nanocomposites using polypropylene (PP) grafted with amine alcohol (PPgDMAE) as compatibilizer were prepared by two different methods. Maleic anhydride grafted PP (PPgMA) was reacted with 2 [2 (dimethylamine) ethoxy] ethanol (DMAE) in the melt for forming amine alcohol functionalized polypropylene (PPgDMAE) Nanocomposites were prepared by two methods. In one method, PP/GO nanocomposite was prepared by direct melt mixing in an internal batch mixer using PPgDMAE as compatibilizer. In another method, a previous mixing of PPgDMAE with GO in hot Xilene was done and then, once the solvent was evaporated, it was incorporated into PP by melt mixing. The microstructure and interface enhancement of the prepared composites were analyzed by Fourier transform infrared spectroscopy (FTIR) Raman, X ray difraction (DRX) contact angle, scanning and transmission electron microscopy (STEM) mechanical, thermal, and electrical properties measurements. Fourier transform infrared spectroscopy (FTIR) revealed the interaction between GO and PPgDMAE. The loading of GO conducted to enhance the composite mechanical properties attributed to the strong interfacial interactions between GO and PPgDMAE. A significant improvement in mechanical thermal stability and electrical properties was observed when nanocomposites were prepared by the solution blending method compared with melt mixing method. This work suggests a potential application of GO in preparation of high performance PP composites. POLYM. COMPOS. 2016. (c) 2016 Society of Plastics Engineers", "author_names": [ "Saul Sanchez-Valdes", "A G Zapata-Dominguez", "J G Martinez-Colunga", "Juan Mendez-Nonell", "Luis Francisco Ramos Valle", "Adriana Berenice Espinoza-Martinez", "Ana Beatriz Morales-Cepeda", "Tomas Lozano-Ramirez", "Pierre G Lafleur", "E Ramirez-Vargas" ], "corpus_id": 138477410, "doc_id": "138477410", "n_citations": 20, "n_key_citations": 0, "score": 1, "title": "Influence of functionalized polypropylene on polypropylene/graphene oxide nanocomposite properties", "venue": "", "year": 2018 }, { "abstract": "The surface area of a single graphene sheet is 2630 m(2)/g, substantially higher than values derived from BET surface area measurements of activated carbons used in current electrochemical double layer capacitors. Our group has pioneered a new carbon material that we call chemically modified graphene (CMG) CMG materials are made from 1 atom thick sheets of carbon, functionalized as needed, and here we demonstrate in an ultracapacitor cell their performance. Specific capacitances of 135 and 99 F/g in aqueous and organic electrolytes, respectively, have been measured. In addition, high electrical conductivity gives these materials consistently good performance over a wide range of voltage scan rates. These encouraging results illustrate the exciting potential for high performance, electrical energy storage devices based on this new class of carbon material.", "author_names": [ "Meryl D Stoller", "Sungjin Park", "Yanwu Zhu", "Jin-ho An", "Rodney S Ruoff" ], "corpus_id": 12346319, "doc_id": "12346319", "n_citations": 6545, "n_key_citations": 42, "score": 0, "title": "Graphene based ultracapacitors.", "venue": "Nano letters", "year": 2008 }, { "abstract": "Abstract Despite the great potential of graphene as the nanofiller, to achieve homogeneous dispersion remains the key challenge for effectively reinforcing the polymer. Here, we report an eco friendly strategy for fabricating the polymer nanocomposites with well dispersed graphene sheets in the polymer matrix via first coating graphene using polypropylene (PP) latex and then melt blending the coated graphene with PP matrix. A ~75% increase in yield strength and a ~74% increase in the Young's modulus of PP are achieved by addition of only 0.42 vol% of graphene due to the effective external load transfer. The glass transition temperature of PP is enhanced by ~2.5 degC by incorporating only 0.041 vol% graphene. The thermal oxidative stability of PP is also remarkably improved with the addition of graphene, for example, compared with neat PP, the initial degradation temperature is enhanced by 26 degC at only 0.42 vol% of graphene loading.", "author_names": [ "Pingan Song", "Zhenhu Cao", "Yuanzheng Cai", "Liping Zhao", "Zhengping Fang", "Shenyuan Fu" ], "corpus_id": 137021720, "doc_id": "137021720", "n_citations": 497, "n_key_citations": 8, "score": 1, "title": "Fabrication of exfoliated graphene based polypropylene nanocomposites with enhanced mechanical and thermal properties", "venue": "", "year": 2011 } ]

[ { "abstract": "It was shown both theoretically and experimentally that isotropic indirect couplings in GaAs beyond the nearest neighbors can be measured accurately from the decays of Hahn echoes under fast magic angle spinning. In addition, homonuclear indirect couplings give rise to a shift of the spin echo timing which can be predicted precisely based on the measured isotropic indirect couplings. The decrease of isotropic indirect coupling with increasing distance between two nuclear spins is slower than the prediction of the theory on indirect couplings in semiconductors.", "author_names": [ "Larry D Potter", "Yuan Ting Wu" ], "corpus_id": 95362475, "doc_id": "95362475", "n_citations": 15, "n_key_citations": 0, "score": 1, "title": "NMR measurements of homonuclear indirect couplings in GaAs", "venue": "", "year": 1995 }, { "abstract": "We study decoherence of nuclear spins in a nanoscale GaAs device based on resistively detected nuclear magnetic resonance (NMR) We demonstrate how the spin echo technique can be modified for our system, and this is compared to the damping of Rabi type coherent oscillations. By selectively decoupling nuclear nuclear and electron nuclear spin, we determine decoherence rates due to individual mechanisms, namely, direct or indirect dipole coupling between different or like nuclides and electron nuclear spin coupling. The data reveal that the indirect dipole coupling between Ga and As mediated by conduction electrons has the strongest contribution, whereas the direct dipole coupling between them has the smallest, reflecting the magic angle condition between the As Ga bonds and the applied magnetic field.", "author_names": [ "Go Yusa", "Norio Kumada", "Koji Muraki", "Yoshiro Hirayama" ], "corpus_id": 118499723, "doc_id": "118499723", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Individual Mechanisms of Nuclear Spin Decoherence in a Nanoscale GaAs NMR Device", "venue": "", "year": 2005 }, { "abstract": "Among the MR techniques playing on dipolar interaction (Hd) the magic sandwich echo sequence (MSE) is very seldom used in biological application. So far, the magic echo has been compared to the spin echo. However, MSE is closer to a stimulated echo thus a Magic Sandwich to Stimulated echo relative change (MaSteR) is of interest to study. The MaSteR evolution with spin lock intensity increase was studied for thawed tendon for different orientations within B0 to modulate the dipolar interaction. We show that MaSteR is correlated to dipolar interaction, sample composition and its evolution with orientation is sensitive to Hd sign. Summary (250 characters) A marker of macromolecular dipolar interactions (Hd) is introduced as the Magic Sandwich to Stimulated Echo relative change (MaSteR) Different B1 spin lock intensities are used to modulate Hd. MaSteR is sensitive to Hd sign and fiber orientation.", "author_names": [ "Eloise Mougel", "Helene Ratiney", "Eric Van Reeth", "Kevin Tse-Ve-Koon", "Kevin Tse Ve Koon", "Olivier Beuf", "Denis Grenier" ], "corpus_id": 229539146, "doc_id": "229539146", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Magic Sandwich to Stimulated Echo Relative change to identify sign and intensity of dipolar interaction in anisotropic tissue", "venue": "", "year": 2020 }, { "abstract": "To investigate the magic angle effect in three dimensional ultrashort echo time Cones Adiabatic T1r (3D UTE Cones AdiabT1r) imaging of articular cartilage at 3T.", "author_names": [ "Mei Wu", "Yajun Ma", "Akhil Kasibhatla", "Mingxin Chen", "Hyungseok Jang", "Saeed Jerban", "Eric Y Chang", "Jiang Du" ], "corpus_id": 218678408, "doc_id": "218678408", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Convincing evidence for magic angle less sensitive quantitative T1r imaging of articular cartilage using the 3D ultrashort echo time cones adiabatic T1r (3D UTE cones AdiabT1r) sequence", "venue": "Magnetic resonance in medicine", "year": 2020 }, { "abstract": "The protons in collagen rich musculoskeletal (MSK) tissues such as the Achilles tendon are subject to strong dipolar interactions which are modulated by the term (3cos2th 1) where th is the angle between the fiber orientation and the static magnetic field B0. The purpose of this study was to investigate the magic angle effect in three dimensional ultrashort echo time Cones Adiabatic T1r (3D UTE Cones AdiabT1r) imaging of the Achilles tendon using a clinical 3 T scanner. The magic angle effect was investigated by Cones AdiabT1r imaging of five cadaveric human Achilles tendon samples at five angular orientations ranging from 0deg to 90deg relative to the B0 field. Conventional Cones continuous wave T1r (Cones CW T1r) and Cones T2* (Cones T2* sequences were also applied for comparison. On average, Cones AdiabT1r increased 3.6 fold from 13.6 1.5 ms at 0deg to 48.4 5.4 ms at 55deg, Cones CW T1r increased 6.1 fold from 7.0 1.1 ms at 0deg to 42.6 5.2 ms at 55deg, and Cones T2* increased 12.3 fold from 2.9 0.5 ms at 0deg to 35.8 6.4 ms at 55deg. Although Cones AdiabT1r is still subject to significant angular dependence, it shows a much reduced magic angle effect compared to Cones CW T1r and Cones T2* and may be used as a novel and potentially more effective approach for quantitative evaluation of the Achilles tendon and other MSK tissues.", "author_names": [ "Mei Wu", "Yajun Ma", "Lidi Wan", "Saeed Jerban", "Hyungseok Jang", "Eric Y Chang", "Jiang Du" ], "corpus_id": 218758280, "doc_id": "218758280", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Magic angle effect on adiabatic T1r imaging of the Achilles tendon using 3D ultrashort echo time cones trajectory", "venue": "NMR in biomedicine", "year": 2020 }, { "abstract": "In this work, we studied the photon echo from heavy hole excitons in a thin InGaAs/GaAs quantum well. To analyze the results, we used the model of an ensemble of two level systems. The model allows us to describe the temporal profile and the moment of arrival of the echo signal, as well as the echo amplitude decay with increasing delay between pulses. In addition, excitation induced dephasing effect was observed, that was beyond the limits of applicability of the model.", "author_names": [ "I I Yanibekov", "I A Solovev", "S A Eliseev", "Yu P Efimov", "V A Lovcjus", "Yury V Kapitonov" ], "corpus_id": 216231938, "doc_id": "216231938", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Difference in the behavior of the photon echo of excitons in InGaAs/GaAs quantum wells from the predictions of the model of two level system ensemble", "venue": "", "year": 2020 }, { "abstract": "Time domain nuclear magnetic resonance techniques are frequently used in polymer, pharmaceutical, and food industries as they offer rapid experimentation and generally do not require any considerable preliminary sample preparation. Detection of solid and liquid fractions in a sample is possible with the free induction decay (FID) However, for the classical FID sequence that consists of a single pulse followed by relaxation decay acquisition, the dead time of the probe (ring out of resonance circuitry) occurs and varies between 5 and 15 ms for standard 10 mm tubes. In such a case, there arises a risk that the signal from the solid fraction cannot be detected correctly. To obtain quantitative measurement on crystalline and more mobile amorphous fractions, alternative sequences to the classical FID in the solid state nuclear magnetic resonance were developed. Solid echo and magic sandwich echo sequences perform the relaxation decay refocusing somehow excluding the dead time problem and allow detection of the signal from the solid fraction. In this study, knowledge of amorphous/crystal fraction, which is obtained through solid echo and magic sandwich echo, has been explored on powder sugar samples for the purpose of developing a groundwork for a reliable quality control method. Different sugars were examined for the utilization of the sequences. What is important to add and make this study unique is that the method proposed did not involve multiparameter fitting of the \"bead\" pattern FID signal that normally suffers from ambiguity; just the integration of the fast Fourier transform of the solid echo was needed to calculate the second moment, (M2)", "author_names": [ "Leonid Yu Grunin", "Mecit Halil Oztop", "Selen Guner", "Saadet Fatma Baltaci" ], "corpus_id": 76665051, "doc_id": "76665051", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Exploring the crystallinity of different powder sugars through solid echo and magic sandwich echo sequences", "venue": "Magnetic resonance in chemistry MRC", "year": 2019 }, { "abstract": "Title Detection of nuclear spin coherence in GaAs through spin echo measurements using electrical spin injection [an abstract of dissertation and a summary of dissertation review] Author(s) Lin Zhi Chao Citation Bei Hai Dao Da Xue Bo Shi (Gong Xue Jia Di 13517Hao Issue Date 2019 03 25 Doc URL http:/hdl.handle.net/2115/74204 Rights(URL) https:/creativecommons.org/licenses/by nc sa/4.0/ Type theses (doctoral abstract and summary of review) Additional Information There are other files related to this item in HUSCAP. Check the above URL. File Information Zhichao_Lin_abstract.pdf (Lun Wen Nei Rong noYao Zhi", "author_names": [ "Lin Zhi Chao" ], "corpus_id": 195577012, "doc_id": "195577012", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Detection of nuclear spin coherence in GaAs through spin echo measurements using electrical spin injection [an abstract of dissertation and a summary of dissertation review]", "venue": "", "year": 2019 }, { "abstract": "Low field nuclear magnetic resonance (NMR) has been widely applied in the oil industry as a noninvasive technique for rock analysis. There are many organic compounds, such as kerogen, in unconventional shale resources. However, it is difficult to evaluate solid organic matter in shales using common NMR techniques. Previous work has shown the use of a solid echo on shale samples provides more information than the standard T1 T2 method with spin echo. But for multiple homonuclear dipolar coupling present in shales, solid echo is less efficient. We propose a new multimagic echo sequence for T1 and T1 T2 measurements. The magic echo and standard T1 and T2 measurement technologies are combined to provide a more complete evaluation of hydrogen containing shale sample components. Compared with other measurements, magic echo measurements provide more signal of organic matters in shale samples. The additional signal is contributed by homonuclear dipolar coupling in organic matter. The partial least squares regress.", "author_names": [ "Zijian Jia", "Lizhi Xiao", "Zhizhan Wang", "Guangzhi Liao", "Yan Zhang", "Can Liang", "Long Guo" ], "corpus_id": 103404320, "doc_id": "103404320", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "Magic Echo for Nuclear Magnetic Resonance Characterization of Shales", "venue": "", "year": 2017 }, { "abstract": "Quantitative evaluation of the solid and viscous components of unconventional shale rock, namely kerogen and bitumen, is important for understanding reservoir quality. Short transverse coherence times, due to strong 1H 1H dipolar interactions, motivates the application of solid state refocusing pulse sequences that allow for investigating components of the free induction decay that are otherwise obscured by instrumental effects such as probe ringdown. This work reports on static, wide line 1H spectroscopy of shale rock and their extracted components, which include kerogen and bitumen, by the application of solid echo and magic echo pulse sequences. We characterize the efficiency of these cycles as a function of the radio frequency power and inter pulse spacing. Magic echos are shown to provide superior refocusing in comparison to solid echo based experiments, as can be understood from the truncation of the Magnus expansion and ability to also refocus any Iz Hamiltonians (e.g. static field inhomogeneity) We characterize the optimal echo spacing and RF power for two shale samples of different maturity, motivating routine core and cuttings analysis and applications.", "author_names": [ "Gregory S Boutis", "Ravinath Kausik" ], "corpus_id": 12419446, "doc_id": "12419446", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Comparing the efficacy of solid and magic echo refocusing sequences: Applications to 1H NMR echo spectroscopy of shale rock.", "venue": "Solid state nuclear magnetic resonance", "year": 2017 } ]

[ { "abstract": "Organic inorganic hybrid materials promise both the superior carrier mobility of inorganic semiconductors and the processability of organic materials. A thin film field effect transistor having an organic inorganic hybrid material as the semiconducting channel was demonstrated. Hybrids based on the perovskite structure crystallize from solution to form oriented molecular scale composites of alternating organic and inorganic sheets. Spin coated thin films of the semiconducting perovskite (C(6)H(5)C(2)H(4)NH(3)(2)SnI(4) form the conducting channel, with field effect mobilities of 0.6 square centimeters per volt second and current modulation greater than 10(4) Molecular engineering of the organic and inorganic components of the hybrids is expected to further improve device performance for low cost thin film transistors.", "author_names": [ "" ], "corpus_id": 5687231, "doc_id": "5687231", "n_citations": 1444, "n_key_citations": 11, "score": 1, "title": "Organic inorganic hybrid materials as semiconducting channels in thin film field effect transistors", "venue": "Science", "year": 1999 }, { "abstract": "Organic inorganic hybrid perovskite materials promise both the superior carrier mobility of inorganic semiconductors and the processability of organic materials, which make organic inorganic hybrid perovskite materials good substitutes in all the applications put forth for organic materials and extend their application to higher speed devices than is presently possible with either a Si or organic semiconductors. Recent reports have shown high carrier mobility and long electron hole diffusion lengths of organic inorganic hybrid perovskite materials. We have demonstrated a thin film field effect transistor with an organic inorganic hybrid CH3NH3PbI3 material as the semiconducting channel based on these advantages via a low temperature vapor assisted solution process. The obvious electrical field effect is obtained in organic inorganic hybrid CH3NH3PbI3 perovskite TFTs with a field effect mobility of 396.2 cm2 V 1 s 1, current modulation greater than 104, sub threshold current of 0.4035 V per decade and threshold voltage of 3.501 V.", "author_names": [ "Yuxiang Wu", "Juan Li", "Jian Xu", "Yangyang Du", "Like Huang", "Jian Ni", "Hongkun Cai", "Jianjun Zhang" ], "corpus_id": 49386052, "doc_id": "49386052", "n_citations": 46, "n_key_citations": 0, "score": 0, "title": "Organic inorganic hybrid CH3NH3PbI3 perovskite materials as channels in thin film field effect transistors", "venue": "", "year": 2016 }, { "abstract": "Abstract Thin film field effect transistors (TFTs) are an essential part of a variety of modern electronics. Interestingly, organic inorganic hybrid perovskite (OHP) material combines the excellent carrier mobility of inorganic semiconductors and the fabricability of organic materials. Herein a thin film field effect transistor using CH3NH3PbI3 as the semiconducting channel was demonstrated. A feasible strategy was presented by modifying the gold electrode with 4 fluorobenzenethiol to eliminate the hole injection barrier between the electrode and CH3NH3PbI3. In addition, we also improved the interfacial characteristics between the gold electrode and the perovskite film by using molybdenum oxide (MoO3) buffer layer. Finally, high k alumina (Al2O3) was utilized to substitute silicon oxide (SiO2) as the dielectric layer to reach low operating voltage in OHP TFTs. The representative TFT showed superior performance with the subthreshold swing (SS) on/off current ratio and linear field effect mobility (mFE) values of 0.49 V/dec, 104 and 21.41 cm2/V, respectively. Simple low temperature processing technology and prominent device performance made this OHP TFT have broad prospects for low cost, large area, and flexible applications. The device performance is supposed to be further enhanced through molecular engineering in the organic and inorganic components of the hybrid perovskite to fulfil high speed applications.", "author_names": [ "Juan Li", "Zhou-Kun Zhou", "Yuze Peng", "Jianjun Zhang", "Ning Guo", "Yanyan Sun" ], "corpus_id": 219035028, "doc_id": "219035028", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "A novel TFT with organic inorganic hybrid perovskite channel layer", "venue": "", "year": 2020 }, { "abstract": "The structures, optical properties, and field effect mobilities of three semiconducting m fluorophenethylammonium based (C6H4FC2H4NH3)2SnI4 perovskites (m 2, 3, or 4) are reported and compared with the analogous measurements for the nonfluorosubstituted phenethylammonium system, (C6H5C2H4NH3)2SnI4. The (4 fluorophenethylammonium)2SnI4 system adopts a fully ordered monoclinic (P21/c) cell with the lattice parameters a 16.653(2) A, b 8.6049(8) A, c 8.7551(8) A, b 98.644(2)deg, and Z 2. Both (3 fluorophenethylammonium)2SnI4 and (2 fluorophenethylammonium)2SnI4 are refined in a monoclinic (C2/c) subcell with the lattice parameters a 34.593(4) A, b 6.0990(8) A, c 12.254(2) A, b 103.917(2)deg, and Z 4 and a 35.070(3) A, b 6.1165(5) A, c 12.280(1) A, b 108.175(1)deg, and Z 4, respectively. Each hybrid structure consists of sheets of corner sharing distorted SnI6 octahedra separated by bilayers of fluorophenethylammonium cations. The dominant low energy feature in the optical absorption", "author_names": [ "David B Mitzi", "and Christos D Dimitrakopoulos", "Laura L Kosbar" ], "corpus_id": 98311243, "doc_id": "98311243", "n_citations": 243, "n_key_citations": 2, "score": 0, "title": "Structurally Tailored Organic Inorganic Perovskites: Optical Properties and Solution Processed Channel Materials for Thin Film Transistors", "venue": "", "year": 2001 }, { "abstract": "DOI: 10.1002/aelm.201600218 In this study, we demonstrate solution processed In2O3 NWFETs for conventional bottom gate top contacts (BGTC structure) with a multiple nanowire network. Electrospinning is utilized to readily produce a scalable continuous In2O3 nanowire network. After an annealing process to remove the polymer matrix, the polycrystalline nanowire network exhibits a conductive channel property. To improve the FET performance, a bilayer structure comprising insulating zirconium oxide (ZrO2) and a nanowire network is adopted. Having a high binding energy with oxygen, ZrO2 is favorable for the passivation of oxygen related surface defects, firmly securing the nanowire network to the substrate. In addition, Lee et al.[5] reported that electrons can pass through several insulating oxides when those oxides are combined with a semiconducting buffer layer. ZrO2, specifically, has a low work function compared to those of other insulating oxides,[6] so it is often applied to injection layer in organic light emitting diodes or resistive memory layers in resistive random access memory.[7] With a ZrO2 top layer, NWFET performance shows high current on/ off ratio (Ion/Ioff) and field effect mobility (mFET) and small SS and Von. Apart from NWFETs, due to limitations of the analyses of nanowire/thin film structures, a bilayer with In2O3 thin film and ZrO2 is fabricated to investigate the conduction mechanism, which is based on the energy band structure. Figure 1a provides a schematic illustration of the fabrication process of the hybrid In2O3 nanowire/ZrO2 thin film FET. Using a conventional single nozzle electrospinning of indium nitrate/PVP solution, indium/poly(vinylpyrrolidone) (PVP) composite fibers are obtained in the form of a fiber mat onto a p+ Si/SiO2 (100 nm) substrate (Figure 2a) The substrate is used as gate/gate insulator. Subsequent thermal annealing on a hotplate at 400 degC results in an In2O3 nanowire network that adheres to the substrate (Figure 2b and Figure S1, Supporting Information) During thermal annealing, the decomposition of PVP reduces the size of the indium/PVP fiber and some of the fibers are welded spontaneously to form nodes and branches in the randomly oriented nanowire network. The ZrO2 top layer is coated directly on the nanowire network by a solution process using spin coating and annealing process. Finally, using e beam evaporation, the source and drain electrodes are deposited on top of the In2O3 nanowire/ZrO2 thin film composite (Figure S1, Supporting Information) The diameter of the indium oxide nanowires is a Gaussian distribution, in which the average size of 224 nanowires is 35.24 4.80 nm (see Figure S3, Supporting Information) All peaks in the X ray diffraction patterns in Figure 2c correspond to cubic In2O3 crystalline structure with Nanowire field effect transistors (NWFETs) are of great interest for future nanoelectronic application such as logic circuits, chemical/biosensors, and memory/display devices. Among various nanowire materials, indium oxide (In2O3) has received much attention because of its chemical stability, high mobility, and low temperature processibility. 1D nanowires featuring unique crystalline structure and distinctive carrier transport characteristics enable outstanding electrical performance.[1] However, when single nanowire is utilized for channel, its complicated growth and transfer processes are considered as an obstacle due to low yield and inconsistency in chemical and electrical properties. On the other hand, multiple nanowire networks have less deviation and enable more reliable device performance with higher yield, suggesting their great potential for electronic devices. Another issue in nanowires is that the substantial number of oxygen related surface states originating from the large surface to volume ratio results in high off current (Ioff) subthreshold swing (SS) turn on voltage (Von) and vulnerability to environmental stimuli. In this context, various studies have reported the passivation of oxide nanowires with organic or inorganic layers.[2] However, such a passivation process requires selective deposition steps including an additional patterning process. The stacking two heterogeneous metal oxide layers, a process frequently used to engineer a channel layer in a thin film transistor, is an attractive method to passivate the surface of a channel. In this bilayer structure, a top semiconducting layer such as InGaZnO, InZnO, or HfInZnO confines a conducting bottom layer and resulting devices demonstrate high mobility and robust gate bias stability.[3] However, this kind of confinement effect is valid only when the thickness of the bottom layer remains thin usually less than 5 nm; otherwise the channel becomes conductive and the device exhibits large negative Von and off current (Ioff) www.MaterialsViews.com www.advelectronicmat.de", "author_names": [ "Hyungjin Park", "Ki Ro Yoon", "Sungkyun Kim", "Il-Doo Kim", "Jungho Jin", "Yun Hyeok Kim", "Byeong-Soo Bae" ], "corpus_id": 114772997, "doc_id": "114772997", "n_citations": 15, "n_key_citations": 1, "score": 0, "title": "Highly Conducting In2O3 Nanowire Network with Passivating ZrO2 Thin Film for Solution Processed Field Effect Transistors", "venue": "", "year": 2016 }, { "abstract": "Molecular atomic layer deposition (MALD) is employed to fabricate hydroquinone (HQ)/diethyl zinc (DEZ) organic inorganic hybrid semiconductor thin films with accurate thickness control, sharp interfaces, and low deposition temperature. Self limiting growth is observed for both HQ and DEZ precursors. The growth rate remains constant at approximately 2.8 A per cycle at 150 degC. The hybrid materials exhibit n type semiconducting behavior with a field effect mobility of approximately 5.7 cm2 V 1 s 1 and an on/off ratio of over 103 following post annealing at 200 degC in nitrogen. The resulting films are characterized using ellipsometry, Fourier transform infrared spectroscopy (FTIR) transmission electron microscopy (TEM) UV Vis spectroscopy, transistor behavior, and Hall effect measurements. Density functional theory (DFT) and many body perturbation theory within the GW approximation are also performed to assist the explanation and understanding of the experimental results. This research offers n channel materials as valuable candidates for efficient organic CMOS devices.", "author_names": [ "Jie Huang", "Hengji Zhang", "Antonio T Lucero", "Lanxia Cheng", "Santosh Kc", "Jian Wang", "Julia W P Hsu", "Kyeongjae Cho", "Jiyoung Kim" ], "corpus_id": 138636251, "doc_id": "138636251", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Organic inorganic hybrid semiconductor thin films deposited using molecular atomic layer deposition (MALD)", "venue": "", "year": 2016 }, { "abstract": "Hybrid organic/inorganic thin film transistors (TFTs) with bottom contact configuration were fabricated using the Laser Induced Forward Transfer (LIFT) process. The semiconducting polymer P3HT was laser printed from a donor to a receiver substrate in order to form the active layer of the TFTs. With a single laser pulse, P3HT pixels were successfully printed.The printed material was analyzed morphologically by means of Optical Microscopy and its thickness was measured by profilometry. In addition, structural characterization of P3HT thin films before and after laser printing took place by using UV Visible absorption spectroscopy and X Ray Diffraction. It was found that the crystallinity of the investigated films is improved upon annealing. An organic thin film transistor (OTFT) with laser printed P3HT pixel as a channel layer was then fabricated. The OTFTs indicated a field effect mobility up to 2.2310 4 cm2/Vs and an on/off ratio on the order of 10 100.", "author_names": [ "Marina Makrygianni", "Emanuele Verrelli", "Nikolaos Boukos", "Stavros Chatzandroulis", "Dimitris Tsoukalas", "Ioanna Zergioti" ], "corpus_id": 98036933, "doc_id": "98036933", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Laser printing and characterization of semiconducting polymers for organic electronics", "venue": "", "year": 2013 }, { "abstract": "A bs or pt io n RT 120 170 200 250 300 350 400 Early research on polymer electronic devices successfully demonstrated function and performance adequate for specific applications. As a result, the performance of devices fabricated from semiconducting polymers has improved to the point where 'plastic' electronics are now expected to develop into a significant industry with a large market opportunity. However, the limited stability of polymer based devices continues to hinder the path toward commercialization. Because stability in air is critical to the commercialization of polymer electronic devices, discussions concerning the stability of semiconducting polymers have focused on degradation caused by reaction with oxygen and water vapor. Conjugated polymers are, however, generally believed to be incapable of withstanding high temperatures (i.e. temperatures well above the glasstransition temperature, Tg) [6,7] thus, stability at high temperatures has received less attention. The availability of semiconducting polymers that can survive exposure to elevated temperatures would open a variety of new possibilities. For example, since inorganic electronic devices typically require process steps that must be carried out at high temperature (often over 300 8C) semiconducting polymers capable of withstanding high temperatures will enable the fabrication of novel organic inorganic hybrid devices. Here, we report the remarkable stability of the poly(2,7carbazole) derivative, poly[N 900 hepta decanyl 2,7 carbazole alt5,5 (40,70 di 2 thienyl 20,10,30 benzothiadiazole) (PCDTBT; see the inset of Fig. 1a) Prior to this report, there was no known example of a semiconducting polymer that is both stable in air at (and above) room temperature and capable of withstanding high temperatures for extended periods of time. PCDTBT is one of a relatively large class of 'donor acceptor' polycarbazole co polymers. Recently, polymer bulkheterojuction solar cells fabricated with phase separated blends of PCDTBT and PC71BM were demonstrated with internal quantum efficiency approaching 100% power conversion efficiency of 17% in response to monochromatic radiation within the absorption band, and power conversion efficiency of 6.1% in response to solar radiation. To investigate the stability of PCDTBT, we have carried out spectroscopic studies on PCDTBT thin films and transport studies using the field effect transistor (FET) architecture with PCDTBTas the semiconductor material in the channel. Figure 1 shows UV visable (UV vis) absorption spectra of PCDTBT thin films annealed for 15 minutes at various temperatures in air (Fig. 1a) and under N2 atmosphere (Fig. 1b) In air, the p p* absorption spectrum is not affected after exposure to temperatures up to 150 8C. Under N2 atmosphere (Fig 1b) the electronic band structure of PCDTBT is stable after exposure to temperatures as high as 350 8C.", "author_names": [ "Shinuk Cho", "Jung Hwa Seo", "Sung Heum Park", "Serge Beaupre", "Mario Leclerc", "Alan J Heeger" ], "corpus_id": 37131960, "doc_id": "37131960", "n_citations": 155, "n_key_citations": 1, "score": 0, "title": "A thermally stable semiconducting polymer.", "venue": "Advanced materials", "year": 2010 }, { "abstract": "During the last 25 years there has been growing research effort in organic electronics to improve the semiconducting, conducting and light emitting properties of organic materials (polymers, oligomers) and hybrids (organic inorganic composites) through novel synthesis and self assembly techniques. Performance improvements, coupled with the ability to process these materials at low temperatures over large areas on flexible substrates such as plastic or paper, provide unique advantages, generate new applications and form factors to address the growing needs for pervasive computing and enhanced connectivity and autonomy. Electronics based on organics also gained importance because the down scaling of structures in polymer materials can be realized with alternative, comparatively simple and low cost techniques. For a successful introduction of polymer electronics into the market an increase of the performance of the key elements of logic circuitry, the thin film transistors, will be essential. The Joanneum Research Institute of Nanostructured Materials and Photonics now routinely manufactures organic thin film transistors (OFETs) with critical channel lengths of less than a micrometer using various nanoimprinting techniques (hot embossing, UV NIL) We also evaluate and demonstrate alternative concepts for structuring organic materials, which are implementable in electronic and optoelectronic applications. We reproducibly achieve high values for several OFET parameters such as the charge carrier field effect mobility in combination with threshold voltages below 5V and high on/off ratios. We have high control over the organic semiconductor (pentacene) thin film formation, having immediate impact on the excellent electronic parameters of our sub micron OFETs.", "author_names": [ "Gunther Leising", "Barbara Stadlober", "Ursula Haas", "Anja Haase", "Christian Palfinger", "Herbert Gold", "Georg Jakopic" ], "corpus_id": 137213674, "doc_id": "137213674", "n_citations": 32, "n_key_citations": 0, "score": 0, "title": "Nanoimprinted devices for integrated organic electronics", "venue": "", "year": 2006 }, { "abstract": "NOT AVAILABLE ORGANIC TRANSISTOR BASED LARGE SCALE INTEGRATED CIRCUITS. Ananth Dodabalapur, B. Crone, Y.Y. Lin, J. Rogers, Z. Bao, R. Filas, S. Martin, R. Sarpeshkar, H.E. Katz and W.J. Lee, Bell Laboratories, Lucent Technologies, Murray Hill, NJ. The performance characteristics of both p channel and n channel organic/polymeric thinlm transistors have reached a level that have enabled the design and experimental realization of large scale complementary integrated circuits. Successful design of such circuits requires a detailed understanding of the basic physics of operation of such transistors as well as the development or modi cation of a range of software tools. We will describe the DC, transient, and noise properties of transistors made with a number of organic and polymer semiconductors and the characteristics of circuits fabricated by a range of methods. We will also describe the advantages of complementary circuits for applications such as RF Tags. Organic transistors have also been integrated with display elements such as organic light emitting diodes. Design considerations and experimental results from such `smart pixels' will be outlined. THIN FILM ORGANIC INORGANIC FIELD EFFECT TRANSISTORS. C.R. Kagan, D.B. Mitzi, C.D. Dimitrakopoulos, L.L. Kosbar, IBM T.J. Watson Research Center, Yorktown Heights, NY. We report thinlm eld e ect transistors having organic inorganic hybrid materials as the semiconducting channels. Organic inorganic hybrids promise the high carrier mobilities of inorganic semiconductors, but may be deposited by low cost, low temperature solution processes common to organic materials. Organic inorganic perovskites, one subset of hybrid materials, self assemble from solution to form oriented, molecular scale composites of alternating inorganic perovskite sheets and organic layers. Spin coated polycrystalline thinlms of (C H C H NH SnI just one example of an organic inorganic perovskite, forms conducting channels with eld e ect mobilities of 0.6 cm /V sec and on o ratios of 10 The exibility in the chemistry and dimensionality of hybrid materials is exploited to prepare organic inorganic perovskites with alternate organic layers and inorganic frameworks. Tailoring the organic and inorganic components of the perovskites is expected to improve carrier mobility, current modulation, and stability of hybrid materials in thinlm transistors. CRYSTAL ENGINEERING OF NTCDI DERIVATIVES FOR HIGH MOBILITY ELECTRON TRANSPORT IN FETS. H.E. Katz, A.J. Lovinger, J. Johnson, C. Kloc, T. Siegrist, Bell Laboratories, Lucent Technologies, Murray Hill, NJ. Naphthalene 1,4,5,8 tetracarboxylic dianhydride (NTCDA) and its diimide derivatives (NTCDIs) possess moderate n channel eld e ect transistor (nFET) mobilities, observable only under an inert atmosphere. However, by appending suitable substituents on NTCDI nitrogens, 2 3 order of magnitude mobility increases are observed, to 0.1 cm2/Vs. Certain uorinated substituents confer su cient stability for nFET operation in air, and one of them a ords the unprecedented capability of solution nFET fabrication. Crystal structures reveal exceptionally favorable packing geometries. These compounds show the highest mobilities and on/o ratios yet reported for organic based nFETs. TRAPPING IN ORGANIC FIELD EFFECT TRANSISTORS. J.H. Schoen, Ch. Kloc, B. Batlogg, Bell Laboratories, Lucent Technologies, Murray Hill, NJ. Organic eld e ect transistors have reached a performance similar to a Si:H devices with mobilities in the order of 1 cm /Vs and on/o ratios of 10 However, thin lm devices often exhibit instabilities, like hysteresis e ects, threshold voltage shifts, or gate voltage dependent mobilities, during operation. It has been questioned whether this behavior is intrinsic to the organic materials or can be ascribed to extrinsic e ects, such as traps or grain boundaries. We have prepared single and polycrystalline eld e ect transistors based on pentacene and oligothiophenes using di erent insulators. The mobility in high quality single crystal devices increases with decreasing temperature following a power law, indicative of band like charge transport in delocalized states. However, trapping in the bulk semiconductor, at the semiconductor/insulator interface as well as at grain boundaries can signi cantly in uence the characteristics of the devices. Especially, the formation of a potential barrier at grain boundaries due to trapped charge gives rise to thermally activated and gate voltage dependent transport. Furthermore, charged trapping sites can migrate during device operation causing, e.g. threshold voltage shifts. However, these e ects were not observed in pure (intrinsic) single crystalline transistors. Stable operation in air for more than a month is demonstrated. SESSION S2: CONDUCTIVE POLYMERS Chair: Zhenan Bao Tuesday Morning, April 25, 2000 Metropolitan II (Argent) 9,10 ANTHRACENEDIYLIDENE DERIVATIVES: SYNTHESIS, REDOX CHEMISTRY, OPTOELECTRONIC AND STRUCTURAL PROPERTIES. Martin R. Bryce, Department of Chemistry, University of Durham, Durham, ENGLAND. We will present the synthesis of new 9,10 anthracenediylidene systems, especially those bearing 1,3 dithiole substituents, and demonstrate that they are versatile building blocks for redox active materials. We will discuss: (i) photoinduced charge transfer studies and structural properties of donor pi acceptor derivatives of this system [1] (ii) synthesis and properties of novel bridged redox active cyclophanes [2] (iii) structural studies on intermolecular CT complexes of new functionalised derivatives[3] e.g. with TCNQ; (iv) the synthesis and redox behaviour of dendritic polymers incorporating bis(1,3 dithiol 2 ylidene) 9,10 dihydroanthracene units. [1] M.R. Bryce, et al, Chem. Eur. J. 1998, 4, 2580 2592. [2] T. Finn, M.R. Bryce, A.S. Batsanov, J.A.K. Howeard, Chem. Commun. 1999, 1835 1836. [3] M.R. Bryce, et al, Eur. J. Org. Chem. 1999, in press. THE ORGANIC METAL: BASIC SCIENTIFIC BACKGROUND AND TECHNOLOGICAL APPLICATIONS. Bernhard Wessling, Ormecon Chemie, Ammersbek, GERMANY. A special form of polyaniline exhibits metallic properties, so it can be considered as an \\Organic Metal\" It will be shown in what aspects the premetallic powder form is di erent from other polyanilines known", "author_names": [ "Kris J Senecal", "Margaret A Auerbach", "Heidi L Schreuder-Gibson", "" ], "corpus_id": 133610881, "doc_id": "133610881", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "S Electrically Active Polymers Chairs", "venue": "", "year": 2000 } ]

[ { "abstract": "High performance gate drive power supply (GDPS) plays a crucial role in ensuring the reliability and safety of the gate driver for power semiconductor devices. This article focuses on the design of a high voltage insulated GDPS for the 10 kV silicon carbide MOSFET in medium voltage (MV) application. Design considerations, including insulation scheme, high voltage insulated transformer design, and load voltage regulation scheme, are proposed. In addition, the performance of the secondary side regulated (SSR) GDPS and that of the primary side regulated (PSR) GDPS are compared for several aspects, including interwinding capacitance, load voltage regulation rate, conversion efficiency, and hardware complexity. Finally, an SSR GDPS and a PSR GDPS, with an insulation voltage of 20 kV, are built in the lab. The test results demonstrate that the PSR GDPS is more preferable because of lower interwinding capacitance, lower load voltage regulation rate, higher conversion efficiency, and simpler control circuit.", "author_names": [ "Li Zhang", "Shiqi Ji", "Shida Gu", "Xingxuan Huang", "James Palmer", "William Giewont", "Leon M Tolbert" ], "corpus_id": 226424161, "doc_id": "226424161", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Design Considerations for High Voltage Insulated Gate Drive Power Supply for 10 kV SiC MOSFET Applied in Medium Voltage Converter", "venue": "IEEE Transactions on Industrial Electronics", "year": 2021 }, { "abstract": "In this article, we introduce a fractional N all digital phase locked loop (ADPLL) architecture based on a single LC tank, featuring an ultra wide tuning range (TR) and optimized for ultra low area in 10 nm FinFET CMOS. Underpinned by excellent switches in the FinFET technology, a high turn on/off capacitance ratio of LC tank switched capacitors, in addition to an adjustable magnetic coupling technique, yields almost an octave TR from 10.8 to 19.3GHz. A new method to compensate for the tracking bank resolution can maintain its quantization noise level over this wide TR. A new scheme is adopted to overcome the metastability resolution problem in a fractional N ADPLL operation. A low complexity TDC gain estimator reduces the digital core area by progressive averaging and time division multiplexing. Among the published fractional N PLLs with an area smaller than 0.1mm2, this work achieves an rms jitter of 725fs in an internal fractional N mode of ADPLL's phase detector (2.7 4.825GHz) yielding the best overall jitter figure of merit (FOM) of 232dB. This topology features small area (0.034mm2) wide TR (56.5% and good supply noise rejection (1.8%/V) resulting in FOMs with normalized TR (FOMT) of 247dB, and normalized TR and area (FOMTA) of 262dB.", "author_names": [ "Min-Shueh Yuan", "Chia-Chun Liao", "Chih-Hsien Chang", "Yu-Tso Lin", "Tsung-Hsien Tsai", "Tien-Chien Huang", "Hsien-Yuan Liao", "Chung-Ting Lu", "Hung-Yi Kuo", "Augusto Ronchini Ximenes", "Robert Bogdan Staszewski" ], "corpus_id": 233333059, "doc_id": "233333059", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A Compact Transformer Based Fractional N ADPLL in 10 nm FinFET CMOS", "venue": "IEEE Transactions on Circuits and Systems I: Regular Papers", "year": 2021 }, { "abstract": "Social web contains a large amount of information with user sentiment and opinions across different fields. For example, drugs.com provides users' textual review and numeric ratings of drugs. However, text reviews may not always be consistent with the numeric ratings. In this project, we built different classification models to classify user ratings of drugs with their textual review. Multiple supervised machine learning models including Random Forest and Naive Bayesian classifiers were built with drug reviews using TF IDF features as input. Also, transformer based neural network models including BERT, BioBERT, RoBERTa, XLNet, ELECTRA, and ALBERT were built for classification using the raw text as input. Overall, BioBERT model outperformed the other models with the overall accuracy of 87% This research demonstrated that transformer based classification models can be used to classify drug reviews and identify reviews that are inconsistent with the ratings.", "author_names": [ "A A Shiju", "Z He" ], "corpus_id": 233306502, "doc_id": "233306502", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Classifying Drug Ratings Using User Reviews with Transformer Based Language Models", "venue": "medRxiv", "year": 2021 }, { "abstract": "Transformer based neural networks have heavily impacted the field of natural language processing, outperforming most previous state of the art models. However, well known models such as BERT, RoBERTa, and GPT 2 require a huge compute budget to create a high quality contextualised representations. In this paper, we study several efficient pre training objectives for Transformersbased models. By testing these objectives on different tasks, we determine which of the ELECTRA model's new features is the most relevant: (i) Transformers pre training can be improved when the input is not altered with artificial symbols, e.g. masked tokens; and (ii) loss functions computed using the whole output reduce training time. (iii) Additionally, we study efficient models composed of two blocks: a discriminator and a simple generator (inspired by the ELECTRA architecture) Our generator is based on a much simpler statistical approach, which minimally increases the computational cost. Our experiments show that it is possible to efficiently train BERT like models using a discriminative approach as in ELECTRA but without a complex generator. Finally, we show that ELECTRA largely benefits from a deep hyper parameter search.", "author_names": [ "Luca Di Liello", "Matteo Gabburo", "Alessandro Moschitti" ], "corpus_id": 233306960, "doc_id": "233306960", "n_citations": 2, "n_key_citations": 1, "score": 0, "title": "Efficient pre training objectives for Transformers", "venue": "ArXiv", "year": 2021 }, { "abstract": "In this work, we show the process of building a large scale training set from digital and digitized collections at a national library. The resulting Bidirectional Encoder Representations from Transformers (BERT) based language model for Norwegian outperforms multilingual BERT (mBERT) models in several token and sequence classification tasks for both Norwegian Bokmal and Norwegian Nynorsk. Our model also improves the mBERT performance for other languages present in the corpus such as English, Swedish, and Danish. For languages not included in the corpus, the weights degrade moderately while keeping strong multilingual properties. Therefore, we show that building high quality models within a memory institution using somewhat noisy optical character recognition (OCR) content is feasible, and we hope to pave the way for other memory institutions to follow.", "author_names": [ "Per Egil Kummervold", "Javier de la Rosa", "Freddy Wetjen", "Svein Arne Brygfjeld" ], "corpus_id": 233307467, "doc_id": "233307467", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Operationalizing a National Digital Library: The Case for a Norwegian Transformer Model", "venue": "NODALIDA", "year": 2021 }, { "abstract": "We probe pre trained transformer language models for bridging inference. We first investigate individual attention heads in BERT and observe that attention heads at higher layers prominently focus on bridging relations in comparison with the lower and middle layers, also, few specific attention heads concentrate consistently on bridging. More importantly, we consider language models as a whole in our second approach where bridging anaphora resolution is formulated as a masked token prediction task (Of Cloze test) Our formulation produces optimistic results without any fine tuning, which indicates that pre trained language models substantially capture bridging inference. Our further investigation shows that the distance between anaphor antecedent and the context provided to language models play an important role in the inference.", "author_names": [ "Onkar Arun Pandit", "Yufang Hou" ], "corpus_id": 233296222, "doc_id": "233296222", "n_citations": 2, "n_key_citations": 0, "score": 1, "title": "Probing for Bridging Inference in Transformer Language Models", "venue": "NAACL", "year": 2021 }, { "abstract": "Major depressive disorder (MDD) is a prevalent psychiatric disorder that is associated with significant healthcare burden worldwide. Phenotyping of MDD can help early diagnosis and consequently may have significant advantages in patient management. In prior research MDD phenotypes have been extracted from structured Electronic Health Records (EHR) or using Electroencephalographic (EEG) data with traditional machine learning models to predict MDD phenotypes. However, MDD phenotypic information is also documented in free text EHR data, such as clinical notes. While clinical notes may provide more accurate phenotyping information, natural language processing (NLP) algorithms must be developed to abstract such information. Recent advancements in NLP resulted in state of the art neural language models, such as Bidirectional Encoder Representations for Transformers (BERT) model, which is a transformer based model that can be pre trained from a corpus of unsupervised text data and then fine tuned on specific tasks. However, such neural language models have been underutilized in clinical NLP tasks due to the lack of large training datasets. In the literature, researchers have utilized the distant supervision paradigm to train machine learning models on clinical text classification tasks to mitigate the issue of lacking annotated training data. It is still unknown whether the paradigm is effective for neural language models. In this paper, we propose to leverage the neural language models in a distant supervision paradigm to identify MDD phenotypes from clinical notes. The experimental results indicate that our proposed approach is effective in identifying MDD phenotypes and that the BioClinical BERT, a specific BERT model for clinical data, achieved the best performance in comparison with conventional machine learning models.", "author_names": [ "Bhavani Singh Agnikula Kshatriya", "Nicolas A Nunez", "Manuel Gardea-Resendez", "Euijung Ryu", "Brandon J Coombes", "Sunyang Fu", "Mark A Frye", "Joanna M Biernacka", "Yanshan Wang" ], "corpus_id": 233307290, "doc_id": "233307290", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Neural Language Models with Distant Supervision to Identify Major Depressive Disorder from Clinical Notes", "venue": "ArXiv", "year": 2021 }, { "abstract": "Increasing concerns and regulations about data privacy, necessitate the study of privacypreserving methods for natural language processing (NLP) applications. Federated learning (FL) provides promising methods for a large number of clients (i.e. personal devices or organizations) to collaboratively learn a shared global model to benefit all clients, while allowing users to keep their data locally. To facilitate FL research in NLP, we present the FedNLP1, a research platform for federated learning in NLP. FedNLP supports various popular task formulations in NLP such as text classification, sequence tagging, question answering, seq2seq generation, and language modeling. We also implement an interface between Transformer language models (e.g. BERT) and FL methods (e.g. FedAvg, FedOpt, etc. for distributed training. The evaluation protocol of this interface supports a comprehensive collection of non IID partitioning strategies. Our preliminary experiments with FedNLP reveal that there exists a large performance gap between learning on decentralized and centralized datasets opening intriguing and exciting future research directions aimed at developing FL methods suited to NLP tasks.", "author_names": [ "Bill Yuchen Lin", "ZiHang Zeng", "Hulin Wang", "Yufen Huang", "Mahdi Soltanolkotabi", "Xiang Ren", "Salman Avestimehr" ], "corpus_id": 233296602, "doc_id": "233296602", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "FedNLP: A Research Platform for Federated Learning in Natural Language Processing", "venue": "ArXiv", "year": 2021 }, { "abstract": "Transformer based pre trained language models have significantly improved the performance of various natural language processing (NLP) tasks in the recent years. While effective and prevalent, these models are usually prohibitively large for resource limited deployment scenarios. A thread of research has thus been working on applying network pruning techniques under the pretrain then finetune paradigm widely adopted in NLP. However, the existing pruning results on benchmark transformers, such as BERT, are not as remarkable as the pruning results in the literature of convolutional neural networks (CNNs) In particular, common wisdom in pruning CNN states that sparse pruning technique compresses a model more than that obtained by reducing number of channels and layers, while existing works on sparse pruning of BERT yields inferior results than its small dense counterparts such as TinyBERT. In this work, we aim to fill this gap by studying how knowledge are transferred and lost during the pre train, fine tune, and pruning process, and proposing a knowledge aware sparse pruning process that achieves significantly superior results than existing literature. We show for the first time that sparse pruning compresses a BERT model significantly more than reducing its number of channels and layers. Experiments on multiple data sets of GLUE benchmark show that our method outperforms the leading competitors with a 20 times weight/FLOPs compression and neglectable loss in prediction accuracy.", "author_names": [ "Dongkuan Xu", "Ian En-Hsu Yen", "Jinxi Zhao", "Zhibin Xiao" ], "corpus_id": 233297003, "doc_id": "233297003", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Rethinking Network Pruning under the Pre train and Fine tune Paradigm", "venue": "NAACL", "year": 2021 }, { "abstract": "We present the Hierarchical Transformer Networks for modeling long term dependencies across clinical notes for the purpose of patientlevel prediction. The network is equipped with three levels of Transformer based encoders to learn progressively from words to sentences, sentences to notes, and finally notes to patients. The first level from word to sentence directly applies a pre trained BERT model, and the second and third levels both implement a stack of 2 layer encoders before the final patient representation is fed into the classification layer for clinical predictions. Compared to traditional BERT models, our model increases the maximum input length from 512 words to much longer sequences that are appropriate for long sequences of clinical notes. We empirically examine and experiment with different parameters to identify an optimal trade off given computational resource limits. Our experimental results on the MIMIC III dataset for different prediction tasks demonstrate that our proposed hierarchical model outperforms previous state of the art hierarchical neural networks1. Codes are available at https:/github.com/Yuqi92/hier_ transformer_networks.", "author_names": [ "Yuqi Si", "Kirk Roberts" ], "corpus_id": 233296642, "doc_id": "233296642", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Hierarchical Transformer Networks for Longitudinal Clinical Document Classification", "venue": "ArXiv", "year": 2021 } ]

[ { "abstract": "Abstract The utilization of solar irradiation to supply energy or to initiate chemical reactions is already an established idea. If a wide band gap semiconductor like titanium dioxide (TiO 2 is irradiated with light, excited electron hole pairs result that can be applied in solar cells to generate electricity or in chemical processes to create or degrade specific compounds. Recently, a new process used on the surface of TiO 2 films, namely, photoinduced superhydrophilicity, is described. All three appearances of the photoreactivity of TiO 2 are discussed in detail in this review, but the main focus is on the photocatalytic activity towards environmentally hazardous compounds (organic, inorganic, and biological materials) which are found in wastewater or in air. Besides information on the mechanistical aspects and applications of these kinds of reactions, a description of the attempts and possibilities to improve the reactivity is also provided. This paper would like to assist the reader in getting an overview of this exciting, but also complicated, field.", "author_names": [ "Oana Carp", "Carolien L Huisman", "Armin Reller" ], "corpus_id": 95781156, "doc_id": "95781156", "n_citations": 3802, "n_key_citations": 99, "score": 1, "title": "Photoinduced reactivity of titanium dioxide", "venue": "", "year": 2004 }, { "abstract": "The reactivity of NO(2) on irradiated TiO(2)/SiO(2) films was studied, with different TiO(2) contents, as proxies for NO(x) de polluting materials. The influence of the photocatalyst concentration, the role of molecular oxygen and the effect of nitrate on the reactivity of TiO(2) films were investigated. NO, HONO and nitrate anions are produced as a consequence of the NO(2) loss on UV illuminated TiO(2) films. The photoinduced nitrate conversion into NO(x) and HONO at the TiO(2) surface is discussed as being a renoxification process, which involves the NO(3) radical. The presence of O(2) in the carrier gas modifies the NO and HONO production yields in the heterogeneous reaction between NO(2) and TiO(2) as well as the products of the renoxification process. Depending on the nature of the surface, the interaction between NO(2) and nitrate with TiO(2) may generate HONO that may have a negative impact on air quality.", "author_names": [ "Maria Eugenia Monge", "Barbara d'Anna", "Christian George" ], "corpus_id": 46189909, "doc_id": "46189909", "n_citations": 88, "n_key_citations": 2, "score": 0, "title": "Nitrogen dioxide removal and nitrous acid formation on titanium oxide surfaces an air quality remediation process?", "venue": "Physical chemistry chemical physics PCCP", "year": 2010 }, { "abstract": "Special surfaces based on titanium dioxide are developed for prevention of nosocomial infections. The reactive oxygen species (ROS) have been generated by the surfaces after their UV irradiation. ROS caused destruction of bacteria. However, effectiveness of bactericidal activity of TiO 2 films depends on several factors. Influence of time of UV irradiation, thermal (annealing) and chemical (benzene) treatment of films on the bactericidal activity, as well as the bactericidal effect against suspended and lyophilized bacteria have been studied. Three clinical isolates Staphylococcus aureus 956, Staphylococcus epidermidis 1061, Escherichia coli 321 5 have been used. Viability of the suspended bacteria has been determined with use of the classical method of counting CFU, viability of lyophilized bacteria has been determined with use of the method of estimation of coefficients of bactericidal extinction of control and test samples. It has been shown that the bactericidal effect of thin films against all strains increased with an increase in the flow of UV exposure. dermal and chemical treatment caused bactericidal activity recovery which was lost during the initial incubation of the bacterial suspension on the surface. Absence of fluid in the system increased the bactericidal activity of TiO 2 films.", "author_names": [ "Svetlana N Pleskova", "Pleskova Svetlana Nikolaevna", "Irina S Golubeva", "S GolubevaI", "Yu K Verevkin", "K VerevkinIu" ], "corpus_id": 135577540, "doc_id": "135577540", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "CONDITIONING OF PHOTOINDUCED BACTERICIDAL ACTIVITY ON SURFACE OF TITANIUM DIOXIDE FILMS", "venue": "", "year": 2013 }, { "abstract": "Titanium dioxide thin films have been prepared by reactive sputtering onto the surface of tracketched polyethylene terephthalate membranes using an inverted dc magnetron, and their structural and physicochemical properties have been examined. A silver film applied onto the membrane surface by physical vapor deposition has been used to protect the polymer from the photocatalytic action of titanium dioxide. The structural characteristics of the composite membranes have been studied by scanning electron microscopy, X ray diffraction, Raman spectroscopy, spectrophotometry, and atomic force microscopy. The effects of photoinduced surface hydrophilization and catalytic decomposition of the dye rhodamine 6G have been investigated.", "author_names": [ "O V Artoshina", "A Rossouw", "V K Semina", "Alexander Nechaev", "Pavel Y Apel" ], "corpus_id": 100754984, "doc_id": "100754984", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Structural and physicochemical properties of titanium dioxide thin films obtained by reactive magnetron sputtering, on the surface of track etched membranes", "venue": "Petroleum Chemistry", "year": 2015 }, { "abstract": "Abstract A series of nitrogen doped 2D titanium dioxide nanosheets was synthesized via green and facile procedure from the lyophilized aqueous colloids of peroxo titanic acid by urea addition and annealing in the temperature range of 350 500 degC. Detailed structural characterization (SEM, TEM with EDX, XRD) of N doped TiO2 confirmed their 2D foil morphology composed of packed anatase nanocrystals. CHNS analysis showed that the total nitrogen content in the N doped TiO2 nanosheets is comparable (0.3 wt. and as shown in the EPR measurements in solid state, the annealing temperature determines the character of the nitrogen species incorporated in the anatase lattice. Paramagnetic nitrogen bulk centers N b dominate the X and Q band EPR spectra of the synthesized N doped TiO2 annealed up to 400 degC, while NO species were detected in samples annealed at higher temperatures. The photoexcitation of the N doped anatase nanosheets resulted in an intense increase of the N b signal intensity, especially upon VIS light exposure, reflecting the selective photoexcitation of the material via diamagnetic N b centers. Nevertheless, the situation upon irradiation of dispersed systems is rather different and to link the information on the structure of the nanosheets with their photoinduced performance in suspensions, the indirect techniques of EPR spectroscopy were applied. Effective generation of paramagnetic reactive oxygen species (ROS) upon UV photoexcitation of the N doped TiO2 nanopowders dispersed in water or dimethylsulfoxide was confirmed by EPR spin trapping technique. The VIS light induced ROS formation was significantly lower and correlates well with the results obtained by the photocatalytic decomposition of 4 chlorophenol upon VIS light. Even though the OH induced capacity of N doped TiO2 prevails upon UV exposure, the VIS irradiation evokes the formation of photoelectrons capable of the selective reduction processes as demonstrated by the one electron reduction of 2,2' azinobis(3 ethylbenzothiazoline 6 sulfonate) radical cation, where the form of nitrogen dopant (e. g. the presence of N b N b in the anatase structure showed a clear effect on the reaction rate. The prepared visible light active N doped TiO2 nanosheets exhibiting also adequate UV photoactivity represent promising materials for further development of solar light active photocatalysts.", "author_names": [ "Zuzana Barbierikova", "Eva Plizingrova", "Monika Motlochova", "Petr Bezdicka", "Jaroslav Bohacek", "Dana Dvoranova", "Milan Mazur", "Jaroslav Kupcik", "Jaromir Jirkovsky", "Jan Subrt", "Josef Krysa", "Vlasta Brezova" ], "corpus_id": 103455379, "doc_id": "103455379", "n_citations": 30, "n_key_citations": 0, "score": 0, "title": "N Doped titanium dioxide nanosheets: Preparation, characterization and UV/visible light activity", "venue": "", "year": 2018 }, { "abstract": "The DNA damage caused by TiO2 under in vitro conditions by UV A exposure in the presence of anionic vesicles of Aerosol OT (AOT) was investigated. The supercoiled form (S) in DNA plasmids was converted to the linear form (L) via the relaxed form (R) The DNA damage was slower in the presence of AOT vesicles prepared in aqueous NaCl solution. Moreover, the presence of AOT vesicles in solution after 6 h of UV irradiation was confirmed with an optical microscope. Probably, a fraction of the DNA was protected by random trapping during sonication. However, the addition of NaCl needed for the vesicle formation can decrease the TiO2 activity. On the other hand, in the absence of vesicles the NaCl concentration led to a profound influence on the adsorption of DNA onto the TiO2 surface. During UV irradiation, the degradation rate of DNA increased with increasing the salt concentration. Solutions containing vesicles were prepared at various NaCl concentrations between 10 mM and 75 mM. Consequently, the salt concentration had no significant effect on the DNA damage. The presence of NaCl can play a deleterious role during the photoinduced process. However, the encapsulation of a fraction of DNA is not excluded. In such conditions, the DNA could be protected against the reactive oxygen species.", "author_names": [ "Fabrice Arsac", "Hisao Hidaka" ], "corpus_id": 35116834, "doc_id": "35116834", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "DNA damage photoinduced by titanium dioxide in the presence of anionic vesicles under uv illumination: influence of sodium chloride concentration.", "venue": "Journal of oleo science", "year": 2007 }, { "abstract": "Recently, UV irradiation has been reported as a new approach to significantly improve the anticoagulant properties of titanium dioxide (TiO2) films by suppressing fibrinogen adsorption and platelet adhesion. This study focuses on how fibrinogen adsorption of and platelet adhesion to TiO2 films is affected by the duration of UV irradiation. Furthermore, this study intends to describe the link between the suppression effect and the changes in the TiO2 films nature caused by photogenerated reactive oxygen species (ROS) First, we performed UV irradiation in different atmospheres as model 1 to determine the effect of oxygen gas on the anticoagulant properties of TiO2 films. The results showed that the suppression of platelet adhesion induced by UV irradiation depended on the presence of oxygen gas, indicating that ROS were photogenerated, and the ROS induced surface change was related to the improvement in the anticoagulant ability. Then, we fabricated three other types of TiO2 samples in air by varying the UV irradiation time: (1) model 2, comprising fully UV irradiated TiO2 films, (2) model 3, comprising partially UV irradiated TiO2 films, and (3) model 4, comprising fully UV irradiated TiO2 Si micropatterns. The results indicated that UV irradiation affected the anticoagulant properties of TiO2 films in a time dependent manner. UV irradiation on TiO2 films for short duration (e.g. 1 min) evidenced a suppression effect on fibrinogen adsorption and platelet adhesion, an effect that could not be the result of photoinduced superhydrophilicity, increased hydroxyl groups OH) number, or decomposition of the adsorbed hydrocarbon. When the UV irradiation time was longer, this suppression effect extended from the surface of the UV irradiated TiO2 films to the surface of the adjacent masked TiO2 films and the nearby Si surface. This result supported that the suppression effect could be related to the changes in the nature of the TiO2 films that were caused by the photogenerated and diffused ROS. Further, this extension of the suppression effect to the Si surface indicated that the photogenerated ROS could be used to improve the anticoagulant properties of other materials. A prolonged UV irradiation time (e.g. 240 min) may enhance the fibrinogen adsorption of and platelet adhesion to TiO2 films, which could be related to the decomposition of the adsorbed hydrocarbon and the increase in the positive charge. However, when comparing the enhancement effect and the suppression effect, the results showed that the latter was the main one to influence fibrinogen adsorption of and platelet adhesion to TiO2 films. This study provides an important basis for understanding the behavior of UV irradiated TiO2 films as anticoagulant materials.", "author_names": [ "Jiang Chen", "Ping Yang", "Yuzhen Liao", "Jinbiao Wang", "Huiqing Chen", "Hong Sun", "Nan Huang" ], "corpus_id": 2018467, "doc_id": "2018467", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Effect of the duration of UV irradiation on the anticoagulant properties of titanium dioxide films.", "venue": "ACS applied materials interfaces", "year": 2015 }, { "abstract": "Studies have shown that environmentally and biologically relevant coatings on nanoparticle (NP) surfaces can significantly alter the physicochemical properties (e.g. dissolution and aggregation) of particles yet there remain some questions on how these coatings impact reactivity. In this study, we investigated molecular level details of surface adsorption and surface reactivity of titanium dioxide (TiO2) NPs using in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) in the presence of bovine serum albumin (BSA) protein and fulvic acid (FA) which were selected as representative biologically and environmentally relevant molecules. Our results show that both BSA and FA adsorb strongly and irreversibly onto TiO2 NP surfaces at neutral pH and these surface coatings impact the photochemical behavior of TiO2. In particular, we show large differences in the formation of reactive oxygen species (ROS) for coated compared to uncoated TiO2 NPs, as well as differences between the two different coatings. In the absence of any coatings, the photooxidation of solution phase sodium benzoate (BA) to hydroxyl benzoate (major product) is observed. However, this reaction is completely inhibited when TiO2 is coated with BSA and partially inhibited when TiO2 is coated with FA. Additionally, we found that BSA can strongly scavenge ROS generated upon irradiation by quenching the formation of electron hole pairs. In contrast, the behavior of FA shows photoinduced hydrophilicity of the TiO2 coated surface and the generation of ROS, although less than that of the uncoated TiO2 NPs. Overall, these results show that the formation of ROS from TiO2 NPs coated by BSA and FA is reduced. Overall, this study provides insights into the impacts of environmentally and biologically relevant coatings and how they may modify the reactivity of the NPs in the environment. Furthermore, the implications of this study extend to understanding the potential reduced toxicity and impacts of TiO2 NPs with coatings in natural and human impacted ecosystems.", "author_names": [ "Haibin Wu", "Liubin Huang", "Amber Rose", "Vicki H Grassian" ], "corpus_id": 225127940, "doc_id": "225127940", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Impact of surface adsorbed biologically and environmentally relevant coatings on TiO2 nanoparticle reactivity", "venue": "", "year": 2020 }, { "abstract": "Abstract Bi12TiO20/Bi4Ti3O12 composite photocatalyst was investigated as an alternative to the conventionally used titanium dioxide, to tackle the well known drawbacks of fast charge carriers recombination and low quantum efficiency of TiO2. Polycrystalline Bi12TiO20/Bi4Ti3O12 thin films were produced by pulsed DC reactive magnetron co sputtering, a method of high industrial relevance, and compared to titanium dioxide coatings produced with the same technique. Following the deposition process, optimum thermal treatment temperature and length were established, to obtain crystallisation. The synthesised coatings were thoroughly analysed with a range of techniques, including Raman spectroscopy, XRD, SEM, TEM, EDX, XPS and AFM. The photocatalytic properties of Bi12TiO20/Bi4Ti3O12 composite were assessed through methylene blue degradation and E. coli inactivation tests under UV A irradiation. The results indicated considerably higher efficiency of the composite photocatalyst when compared to TiO2. Moreover, the reusability assessment of Bi12TiO20/Bi4Ti3O12 thin films revealed an incremental performance increase after each consecutive test, leading to a 6 fold increase in photocatalytic activity between the first and 15th cycle. Time resolved photoluminescence and XPS analysis highlighted an increased presence of oxygen vacancies, forming over repeated usage of bismuth titanate, leading to longer lifetimes of photogenerated species and enhanced photocatalytic performance.", "author_names": [ "Matthieu Grao", "James Redfern", "Peter J Kelly", "Marina Ratova" ], "corpus_id": 233675100, "doc_id": "233675100", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Magnetron co sputtered Bi12TiO20/Bi4Ti3O12 composite An efficient photocatalytic material with photoinduced oxygen vacancies for water treatment application", "venue": "", "year": 2021 }, { "abstract": "The internal photoeffect in X ray amorphous titanium dioxide (TiO2) films deposited by reactive magnetron sputtering onto silica glass substrates has been studied. It is established that cyclic illumination of samples leads to a change in the photoinduced current kinetics, whereby the kinetic curves initially exhibit an extremum that subsequently decreases and eventually disappears. Using a system of equations that describes the kinetics of free electrons with allowance for their trapping on deep monoenergetic traps, it is shown that the observed behavior is related to a significant increase in the coefficient of interband recombination and a decrease in the concentration of vacant traps.", "author_names": [ "A V Zav'yalov", "Victor Shapovalov", "N S Shutova" ], "corpus_id": 122165780, "doc_id": "122165780", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Kinetics of internal photoeffect in titanium dioxide films", "venue": "", "year": 2011 } ]

[ { "abstract": "Photoelectrochemical (PEC) water splitting is a promising technology that uses light absorbing semiconductors to convert solar energy directly into a chemical fuel (i.e. hydrogen) PEC water splitting has the potential to become a key technology in achieving a sustainable society, if high solar to fuel energy conversion efficiencies are obtained with earth abundant materials. This review article discusses recent developments and discoveries in the mechanisms by which the localized surface plasmon resonance (LSPR) in metallic nanoparticles can increase or complement a neighbouring semiconductor in light absorption for catalytic water splitting applications. These mechanisms can mitigate the intrinsic optical limitations of semiconductors (e.g. metal oxides) for efficient solar water splitting. We identify four types of enhancement mechanisms in the recent literature: (i) light scattering, (ii) light concentration, (iii) hot electron injection (HEI) and (iv) plasmon induced resonance energy transfer (PIRET) (i) Light scattering and (ii) light concentration are light trapping mechanisms that can increase the absorption of light with energies above the semiconductor optical band edge. These two mechanisms are ideal to enhance the absorption of promising semiconductors with narrow bandgap energies that suffer from limited absorption coefficients and bulk charge recombination. On the other hand, (iii) HEI and the recently discovered (iv) PIRET are mechanisms that can enhance the absorption also below the semiconductor optical band edge. Therefore, HEI and PIRET have the potential to extend the light utilization to visible and near infrared wavelengths of semiconductors with excellent electrochemical properties, but with large bandgap energies. New techniques and theories that have been developed to elucidate the above mentioned plasmonic mechanisms are presented and discussed for their application in metal oxide photoelectrodes. Finally, other plasmonic and non plasmonic effects that do not increase the device absorption, but affect the electrochemical properties of the semiconductor (e.g. charge carrier transport) are also discussed, since a complete understanding of these phenomena is fundamental for the design of an efficient plasmonic NP semiconductor water splitting device.", "author_names": [ "Marco Valenti", "Magnus P Jonsson", "George Biskos", "A Schmidt-ott", "Wilson A Smith" ], "corpus_id": 43589656, "doc_id": "43589656", "n_citations": 93, "n_key_citations": 0, "score": 1, "title": "Plasmonic nanoparticle semiconductor composites for efficient solar water splitting", "venue": "", "year": 2016 }, { "abstract": "Abstract We report the application of plasmonic Bi nanoparticles supported rGO/BiVO4 anode for photoelectrochemical (PEC) water splitting. Nearly, 2.5 times higher activity was observed for Bi rGO/BiVO4 composite than pristine BiVO4. Typical results indicated that Bi rGO/BiVO4 exhibits the highest current density of 6.05 mA/cm2 at 1.23 V, whereas Bi BiVO4 showed the current density of only 3.56 mA/cm2. This enhancement in PEC activity on introduction of Bi rGO is due to the surface plasmonic behavior of BiNPs, which improves the absorption of radiation thereby reduces the charge recombination. Further, the composite electrode showed good solar to hydrogen conversion efficiency, appreciable incident photon to current efficiency and low charge transfer resistance. Hence, Bi rGO/BiVO4 provides an opportunity to realize PEC water splitting.", "author_names": [ "Palyam Subramanyam", "Tanmoy Khan", "Gudipati Neeraja Sinha", "Duvvuri Suryakala", "Ch Subrahmanyam" ], "corpus_id": 203938770, "doc_id": "203938770", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Plasmonic Bi nanoparticle decorated BiVO4/rGO as an efficient photoanode for photoelectrochemical water splitting", "venue": "", "year": 2020 }, { "abstract": "Abstract Plasmonic metal nanoparticles containing photoanodes are known to exhibit stable photoelectrochemical (PEC) performance due to their optical and electronic properties. In this work, we report the application of plasmonic Bi nanoparticles supported over a g C3N4/Bi2S3 photoanode for PEC water splitting. Typical results indicated that g C3N4/Bi2S3/BiNPs ternary composite photoanode showed a high photo current density of 7.11 mA cm 2 at 1.23 V under solar irradiation, which was 5 and 10 times higher than g C3N4/Bi2S3 and g C3N4 photoanodes, respectively. Further, the composite electrode also demonstrated superior solar to hydrogen efficiency and long term stability. It was concluded that Bi nanoparticles play a major role in enhancing the PEC performance for hydrogen evolution reaction. Thus, g C3N4/Bi2S3/BiNPs has superior PEC performance and proved to work as an alternative to noble metal based photo electrodes for solar water splitting reactions.", "author_names": [ "Palyam Subramanyam", "Bhagat Ram Meena", "Duvvuri Suryakala", "Melepurath Deepa", "Ch Subrahmanyam" ], "corpus_id": 213602494, "doc_id": "213602494", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Plasmonic nanometal decorated photoanodes for efficient photoelectrochemical water splitting", "venue": "", "year": 2020 }, { "abstract": "We report plasmonic Bi metal and rGO decorated on BiVO4 using a simple single step synthesis technique followed by drop casting. Impressive five fold increment in activity is observed on BiVO4@Bi rGO composite compared to pristine BiVO4 under visible light irradiation. This enhancement in photoelectrochemical performance on the introduction of SPR effect of Bi NPs and high electrical conductivity of rGO is ascribed to inhibited charge recombination and enhanced charge injection. The composite BiVO4@Bi rGO exhibit a high photocurrent density of 4.21 mA cm 2 than BiVO4@ Bi electrode whose photocurrent density is 1.91 mA cm 2 at 1.23 V vs RHE. This indicates the synergistic effect of Bi NPs and rGO in the composite. Further, superior solar to hydrogen efficiency, appreciable IPCE and low charge transfer resistance are achieved for this composite. Details on this improved PEC activity of BiVO4@Bi rGO are marked in this work which can be adapted to make more efficient photoanodes.", "author_names": [ "Tanmoy Khan", "Ch Subrahmanyam" ], "corpus_id": 182874572, "doc_id": "182874572", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Plasmonic Bi metal and rGO decorated on BiVO4 as an efficient photoanode for photoelectrochemical water splitting", "venue": "", "year": 2019 }, { "abstract": "This work exploits the ability of the spark discharge particle generator (SDG) to produce metallic nanoparticles (NPs) with control over the size, shape and composition, to unravel the plasmonic mechanisms by which NPs can enhance the photoelectrochemical performance of semiconductor photoanodes. Chapter 1 gives an overview of the SDG and the aerosol technology used in this thesis to synthesize the NPs. Chapter 2 summarizes the different aerosol NP immobilization techniques (both on solids and in liquids) and introduces for the first time an electrospray technique to efficiently capture neutral NPs in liquids. In chapter 3, an extensive literature review on plasmonic photoelectrocatalysis is given to introduce the plasmonic mechanisms that are experimentally studied in Chapter 4, 5, 6 and 7. Chapter 4 and 5 are dedicated to study the hot electron injection (HEI) mechanism by which plasmonic NPs create light induced \"hot\" charge carriers upon illumination that can drive photoelectrochemical reactions. Chapter 4 reveals that alloying Ag NPs with Au can be used to shift in a control way the absorption and utilization of light to longer wavelengths. However, due to the low interband energy of Au (i.e. 2.3 eV) compared to that of Ag (i.e. 3.6 eV) the alloy NPs exhibited more interband excitations when illuminated with visible light than pure Ag NPs. Such increase in interband excitations resulted in lower hot electron energies and HEI efficiencies in the alloy NPs than in pure Ag NPs. Chapter 5, reveals the HEI size dependency of Ag NPs. It is found that smaller NPs (l 10 nm) where the surface induced excitations are prominent result in higher HEI efficiencies, while for larger light absorbing NPs (in the range 10 25 nm) a maximum in the performance is found that corresponds well with the size of the Ag NP with the largest nearfield enhancement. Chapter 6, studies the ability of Ag NPs to concentrate and scatter light into thin film semiconductors to enhance their absorption. It is found that most of the solar energy absorbed by pure 15 nm Ag NPs is lost through heat dissipation. However, larger NPs preferentially scatter the incoming light to the neighbour 6 semiconductor, improving its absorption above their band gap energy. Finally, two configurations of plasmonic NP/semiconductor composites were studied to enhance the semiconductor absorption. In the first configuration the NPs were placed at the semiconductor electrolyte interface and in the second configuration, the NPs were embedded in the semiconductor at the back contact/semiconductor interface. It was found that an absorption enhancement at the semiconductor/electrolyte interface was better utilized due to the ability of the surface charge layer to efficiently separate the extra electron holes induced by the plasmonic NPs.", "author_names": [ "Marco Valenti" ], "corpus_id": 139818221, "doc_id": "139818221", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Spark Discharge as a Nanoparticle Source to Study Size Dependent Plasmonic Properties for Photo electrochemical Water Splitting", "venue": "", "year": 2018 }, { "abstract": "Abstract The rising demand for sustainable and efficient solar energy conversion strategies has triggered the development of a myriad of semiconductor based composite systems for photocatalytic water splitting. Plasmonic nanostructures recently emerged as a promising alternative to conventionally used photosensitizers (e.g. organic dyes) that complement semiconductors as they can uniquely harness the energy of visible photons through the excitation of the localized surface plasmon resonance (LSPR) Provided the solid foundation of the mechanisms with which the plasmonic enhancement effects occur, we herein review the recent progress in the field of plasmonic water splitting by classifying different obstacles and breakthroughs made over the past decade and a half. While plasmonic nanostructures initially served to expand the light harvesting spectrum of semiconductors, rational designs and advanced fabrication techniques have increasingly improved the light absorption capabilities of the plasmonic metal/semiconductor hybrid architectures as a whole. More recently, the use of various analytical tools has allowed a more fundamental issue of short hot carrier lifetime to be tackled which, in turn, has brought about great interest in optimizing the structures and interfaces for more efficient charge transfer. Other issues associated with the field include the complexity of fabrication methods, limited choices in material selection, and cost effectiveness. The review ends with perspectives on future steps to be taken namely the incorporation of co catalysts, the possibility of using plasmonic heating to assist the catalytic activities, and further investigation of the direct interfacial charge transfer mechanism driven by chemical interface damping (CID)", "author_names": [ "Joong Bum Lee", "Shinyoung Choi", "Jeonga Kim", "Yoon Sung Nam" ], "corpus_id": 139586893, "doc_id": "139586893", "n_citations": 32, "n_key_citations": 0, "score": 0, "title": "Plasmonically assisted nanoarchitectures for solar water splitting: Obstacles and breakthroughs", "venue": "", "year": 2017 }, { "abstract": "An ultrasonication assisted in situ deposition strategy was utilised to uniformly decorate plasmonic Ag nanoparticles on vertically aligned TiO2 nanotube arrays (NTAs) to construct a Ag@TiO2 NTA composite. The Ag nanoparticles act as efficient surface plasmon resonance (SPR) photosensitizers to drive photocatalytic water splitting under visible light irradiation. The Ag nanoparticles were uniformly deposited on the surface and inside the highly oriented TiO2 nanotubes. The visible light driven hydrogen production activities of silver nanoparticle anchored TiO2 nanotube array photocatalysts were evaluated using methanol as a sacrificial reagent in water under a 500 W Xe lamp with a UV light cutoff filter (l 420 nm) It was found that the hydrogen production rate of the Ag@TiO2 NTAs prepared with ultrasonication assisted deposition for 5 min was approximately 15 times higher than that of its pristine TiO2 NTAs counterpart. The highly efficient photocatalytic hydrogen evolution is attributed to the SPR effect of Ag for enhanced visible light absorption and boosting the photogenerated electron hole separation/transfer. This strategy is promising for the design and construction of high efficiency TiO2 based photocatalysts for solar energy conversion.", "author_names": [ "Mingzheng Ge", "Chunyan Cao", "Shu-hui Li", "Yu Xin Tang", "Lu-ning Wang", "Ning Qi", "Jianying Huang", "Ke-Qin Zhang", "Salem Slayyem Al-Deyab", "Yuekun Lai" ], "corpus_id": 25871085, "doc_id": "25871085", "n_citations": 171, "n_key_citations": 0, "score": 0, "title": "In situ plasmonic Ag nanoparticle anchored TiO2 nanotube arrays as visible light driven photocatalysts for enhanced water splitting.", "venue": "Nanoscale", "year": 2016 }, { "abstract": "Recent years have seen a renewed interest in the harvesting and conversion of solar energy. Among various technologies, the direct conversion of solar to chemical energy using photocatalysts has received significant attention. Although heterogeneous photocatalysts are almost exclusively semiconductors, it has been demonstrated recently that plasmonic nanostructures of noble metals (mainly silver and gold) also show significant promise. Here we review recent progress in using plasmonic metallic nanostructures in the field of photocatalysis. We focus on plasmon enhanced water splitting on composite photocatalysts containing semiconductor and plasmonic metal building blocks, and recently reported plasmon mediated photocatalytic reactions on plasmonic nanostructures of noble metals. We also discuss the areas where major advancements are needed to move the field of plasmon mediated photocatalysis forward.", "author_names": [ "Suljo Linic", "Phillip Christopher", "David B Ingram" ], "corpus_id": 5403159, "doc_id": "5403159", "n_citations": 3259, "n_key_citations": 20, "score": 0, "title": "Plasmonic metal nanostructures for efficient conversion of solar to chemical energy.", "venue": "Nature materials", "year": 2011 }, { "abstract": "To design an efficient photocatalyst (PC) for semiconductor (SC) mediated, solar driven water dissociation to generate hydrogen, a host of strategies has been adopted, including the fabrication of semiconductor composites, substitution of impurities for achieving extended absorbance, and coating with a metal to promote charge transfer. Despite these efforts, a photocatalyst exhibiting requisite efficiency has not been developed. This article reviews the factors governing the water splitting photoactivity of an SC material, and provides an account of our recent research on this subject. As per our investigations, the mode of adsorption of the water molecules on the semiconductor surface and their subsequent interaction with the charge carriers play a crucial role in the overall performance of a water splitting photocatalyst, rather than the much discussed SC SC or SC metal charge transfer effects alone. The water to SC binding is controlled by a combination of several physicochemical properties of a composite PC, such as the preparation dependent grain morphology, doping affected grain nucleation, pore structure dependent water adsorption/desorption kinetics, exposure of specific facets, and SC/SC or SC/metal interfacial characteristics. Our studies revealed strong particle size dependence and the facet based sensitivity of modified metal sulfide and metal oxide photocatalysts. Additionally, the effect of lattice impurity on quantum efficiency of wide gap metal oxides, such as TiO2, In2TiO5, InVO4, FeNbO4, GaNbO4, GaFeO3, and LaInO3, is related to the lattice defect induced intra bandgap energy levels rather than the doping induced extension of visible region absorbance. Furthermore, the dispersed gold nanoparticles served as distinct reaction sites over the surface of a TiO2 photocatalyst besides their contribution to the plasmonic effect. Our study revealed that under certain spectral overlap conditions, the inter semiconductor charge transfer might cause quenching of the water splitting photoactivity of a composite photocatalyst. We surmise that considering the aforementioned factors should assist in designing an efficient water splitting PC, eventually triggering technological advancements in this field.", "author_names": [ "Narendra M Gupta" ], "corpus_id": 100101107, "doc_id": "100101107", "n_citations": 49, "n_key_citations": 0, "score": 0, "title": "Factors affecting the efficiency of a water splitting photocatalyst: A perspective", "venue": "", "year": 2017 }, { "abstract": "Plasmonic photoelectrochemical (PEC) water splitting is very promising in the conversion of abundant solar energy into chemical energy. However, the solar to hydrogen efficiencies reported so far are still too low for practical use, which can be improved by optimizing the design and synthesis of individual blocks (i. e. the compositions, sizes, shapes of the metal and the coupling semiconductors) and the assembly of these blocks into targeted three dimensional (3D) structures. Here, we constructed a composite plasmonic metal/semiconductor photoanode by decorating gold nanoparticles (Au NPs) on 3D branched ZnO nanowire arrays (B ZnO NWs) through a series of simple solution chemical routes. The 3D ordered Au/B ZnO NWs photoanodes exhibited excellent PEC activities in both ultraviolet and visible region. The improved photoactivities in visible region were demonstrated to be caused by the surface plasmon resonance effect of Au NPs. The photoconversion efficiency of Au/B ZnO NWs photoanode reached 0.52% under simulated sunlight illumination. This is a high value of solar to hydrogen efficiencies reported till nowadays for plasmonic PEC water splitting, which was mainly benefit from the extensive metal/semiconductor interfaces for efficient extraction of hot electron from Au NPs and excellent charge carries collection efficiency of the 3D ordered Au/B ZnO NWs photoelectrode.", "author_names": [ "Xing Zhang", "Yang Liu", "Zhenhui Kang" ], "corpus_id": 34593076, "doc_id": "34593076", "n_citations": 231, "n_key_citations": 1, "score": 0, "title": "3D branched ZnO nanowire arrays decorated with plasmonic au nanoparticles for high performance photoelectrochemical water splitting.", "venue": "ACS applied materials interfaces", "year": 2014 } ]

[ { "abstract": "Two dimensional (2D) materials have been an emerging platform for future device applications. Among them, 2D transition metal dichalcogenides (TMDs) have attracted substantial interest because of their fascinating properties ranging from semiconductor, semimetal, metal, to superconductor. The electric controllability over their physical properties is extremely important for their device application. This feature article presents recent progress in the electrical manipulation of the optical, electric, and spin/valley dependent properties of 2D TMDs. Also, some of the outstanding challenges and opportunities in this promising research field are highlighted.", "author_names": [ "Fucai Liu", "Jiadong Zhou", "Chao Zhu", "Zheng Liu" ], "corpus_id": 100507863, "doc_id": "100507863", "n_citations": 29, "n_key_citations": 0, "score": 1, "title": "Electric Field Effect in Two Dimensional Transition Metal Dichalcogenides", "venue": "", "year": 2017 }, { "abstract": "We studied the nonlinear electric response in WTe2 and MoTe2 monolayers. When the inversion symmetry is breaking but the the time reversal symmetry is preserved, a second order Hall effect called the nonlinear anomalous Hall effect (NLAHE) emerges owing to the nonzero Berry curvature on the nonequilibrium Fermi surface. We reveal a strong NLAHE with a Hall voltage that is quadratic with respect to the longitudinal current. The optimal current direction is normal to the mirror plane in these two dimensional (2D) materials. The NLAHE can be sensitively tuned by an out of plane electric field, which induces a transition from a topological insulator to a normal insulator. Crossing the critical transition point, the magnitude of the NLAHE increases, and its sign is reversed. Our work paves the way to discover exotic nonlinear phenomena in inversion symmetry breaking 2D materials.", "author_names": [ "Yang Zhang", "Jeroen van den Brink", "Claudia Felser", "Binghai Yan" ], "corpus_id": 119184267, "doc_id": "119184267", "n_citations": 61, "n_key_citations": 1, "score": 0, "title": "Electrically tuneable nonlinear anomalous Hall effect in two dimensional transition metal dichalcogenides WTe2 and MoTe2", "venue": "", "year": 2018 }, { "abstract": "Quantum spin Hall (QSH) effect materials feature edge states that are topologically protected from backscattering. However, the small band gap in materials that have been identified as QSH insulators limits applications. We use first principles calculations to predict a class of large gap QSH insulators in two dimensional transition metal dichalcogenides with 1T' structure, namely, 1T' MX2 with M (tungsten or molybdenum) and X (tellurium, selenium, or sulfur) A structural distortion causes an intrinsic band inversion between chalcogenide p and metal d bands. Additionally, spin orbit coupling opens a gap that is tunable by vertical electric field and strain. We propose a topological field effect transistor made of van der Waals heterostructures of 1T' MX2 and two dimensional dielectric layers that can be rapidly switched off by electric field through a topological phase transition instead of carrier depletion. First principles calculations are used to predict an exotic effect in a particular structure of WTe2 and related materials. Predicting an exotic state of matter Much like graphene, twodimensional flakes of transition metal dichalcogenides have appealing electronic properties. Qian et al. now find that certain structures of these materials may also exhibit the so called spin Hall effect. The spin Hall effect represents an exotic state of matter in which a 2D material conducts electricity along its edge in a way that drastically reduces dissipation. To show this, the researchers used first principle calculations and found that the materials also feature a large band gap, which reduces undesirable conduction through the bulk. Their proposed device could be switched on and off quickly using an electric field. Science, this issue p. 1344", "author_names": [ "Xiaofeng Qian", "Junwei Liu", "Liang Fu", "Ju Li" ], "corpus_id": 206559705, "doc_id": "206559705", "n_citations": 824, "n_key_citations": 2, "score": 0, "title": "Quantum spin Hall effect in two dimensional transition metal dichalcogenides", "venue": "Science", "year": 2014 }, { "abstract": "We report a new class of large gap quantum spin Hall insulators in two dimensional transition metal dichalcogenides, namely, MX$_2$ with M=(Mo, W) and X=(S, Se, and Te) whose topological electronic properties are highly tunable by external electric field. We propose a novel topological field effect transistor made of these atomic layer materials and their van der Waals heterostructures. Our device exhibits parametrically enhanced charge spin conductance through topologically protected transport channels, and can be rapidly switched off by electric field through topological phase transition instead of carrier depletion. Our work provides a practical material platform and device architecture for topological quantum electronics.", "author_names": [ "Xiaofeng Qian", "Junwei Liu", "Liang Fu", "Ju Li" ], "corpus_id": 117622601, "doc_id": "117622601", "n_citations": 653, "n_key_citations": 0, "score": 0, "title": "Quantum Spin Hall Effect and Topological Field Effect Transistor in Two Dimensional Transition Metal Dichalcogenides", "venue": "", "year": 2014 }, { "abstract": "The band gap of two dimensional (2D) semiconductors can be efficiently tuned by gate electric field, which is so called the Stark effect. We report that doping, which is essential in realistic devices, will substantially change the Stark effect of few layer transition metal dichalcogenides in unexpected ways. Particularly in bilayer structures, because of the competition between strong quantum confinement and intrinsic screening length, electron and hole dopings exhibit surprisingly different Stark effects: doped electrons actively screen the external field and result in a nonlinear Stark effect; however, doped holes do not effectively screen the external field, causing a linear Stark effect that is the same as that of undoped materials. Our further analysis shows that this unusual doping effect is not limited within transition metal dichalcogenides but general for 2D structures. Therefore, doping plays a much more crucial role in functional 2D devices and this unusual Stark effect also provides a new degree of freedom to tune band gaps and optical properties of 2D materials.", "author_names": [ "Xiaobo Lu", "Li Yang" ], "corpus_id": 119342604, "doc_id": "119342604", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Stark Effect of Doped Two Dimensional Transition Metal Dichalcogenides", "venue": "", "year": 2017 }, { "abstract": "Transition metal dichalcogenides TX2 (T W, Mo; X S, Se, Te) are layered materials that are available in ultrathin forms such as mono bi and multilayers, which are commonly known as two dimensional materials. They have an intrinsic band gap in the range of some 500 meV to 2 eV, depending on the composition and number of layers, and giant intrinsic spin orbit splittings for odd layer numbers, and, in conjunction with their high chemical and mechanical stability, they qualify as candidate materials for two dimensional flexible electronics and spintronics. The electronic structure of each TX2 material is very sensitive to external factors, in particular towards electric and magnetic fields. A perpendicular electric field reduces the band gap, and for some structures semiconductor metal transitions could be possible. Moreover, the electric field triggers the spin orbit splitting for bilayers. A magnetic field applied normal to the layers causes the Hall effect, which in some cases may result in a quantum (spin) Hall effect and thus in magnetic switches. Finally, we discuss how valleytronics is possible in these materials by selective interaction of electrons in the different valleys using polarized light.", "author_names": [ "Agnieszka Beata Kuc", "Thomas Heine" ], "corpus_id": 205905828, "doc_id": "205905828", "n_citations": 117, "n_key_citations": 2, "score": 0, "title": "The electronic structure calculations of two dimensional transition metal dichalcogenides in the presence of external electric and magnetic fields.", "venue": "Chemical Society reviews", "year": 2015 }, { "abstract": "We show that it is possible to obtain one dimensional (1D) spin channels at the lateral heterojunction of 2D transition metal dichalcogenides by a current flow without the necessity of any external magnetic field. This originates from the native spin orbit coupling of 2D materials in conjunction with the electric field that develops due to conduction band offset at the junction. Nonetheless, we show that the underlying physics is very different from the well known spin Hall effect. We find that the degree of spin polarization could be as high as 0.1 <inline formula><tex math notation=\"LaTeX\"/tex math>/inline formula> for conduction band transport and 0.75 <inline formula><tex math notation=\"LaTeX\"/tex math>/inline formula> for valence band transport at room temperature in a lateral heterostructure of typical 2D semiconductors such as <inline formula> <tex math notation=\"LaTeX\"\\rm MoS}_2$/tex math>/inline formula><inline formula><tex math notation=\"LaTeX\"\\rm WSe}_2$/tex math>/inline formula> We also find that the spin polarization increases with longitudinal (transport) effective mass due to increased momentum of the flowing electrons. Such 1D spin channels might allow probing of spin dynamics in confined phase spaces in addition to potentially contributing to spintronics applications.", "author_names": [ "Varun Mishra", "Sayeef S Salahuddin" ], "corpus_id": 52161785, "doc_id": "52161785", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "One Dimensional Spin Channel in Two Dimensional Transition Metal Dichalcogenide Heterostructures", "venue": "IEEE Transactions on Nanotechnology", "year": 2018 }, { "abstract": "The emergence of two dimensional (2D) materials has attracted a great deal of attention due to their fascinating physical properties and potential applications for future nano electronic devices. Since the first isolation of graphene, a Dirac material, a large family of new functional 2D materials have been discovered and characterized, including insulating 2D boron nitride, semiconducting 2D transition metal dichalcogenides and black phosphorus, and superconducting 2D bismuth strontium calcium copper oxide, molybdenum disulphide and niobium selenide, etc. Here, we report the identification of ferromagnetic thin flakes of Cr2Ge2Te6 (CGT) with thickness down to a few nanometers, which provides a very important piece to the van der Waals structures consisting of various 2D materials. We further demonstrate the giant modulation of the channel resistance of 2D CGT devices via electric field effect. Our results illustrate the gate voltage tunability of 2D CGT and the potential of CGT, a ferromagnetic 2D material, as a new functional quantum material for applications in future nanoelectronics and spintronics.", "author_names": [ "Wenyu Xing", "Yangyang Chen", "Patrick Michael Odenthal", "Xiao Zhang", "Wei Yuan", "Tang Su", "Qi Song", "Tianyu Wang", "Jiangnan Zhong", "Shuang Jia", "X C Xie", "Yan Li", "Wei Han" ], "corpus_id": 119324997, "doc_id": "119324997", "n_citations": 109, "n_key_citations": 1, "score": 0, "title": "Electric field effect in multilayer Cr 2 Ge 2 Te 6 a ferromagnetic 2D material", "venue": "", "year": 2017 }, { "abstract": "As two dimensional (2D) transition metal dichalcogenides electronic devices are scaled down to the sub micrometer regime, the active layers of these materials are exposed to high lateral electric fields, resulting in electrical breakdown. In this regard, understanding the intrinsic nature in layer stacked 2D semiconducting materials under high lateral electric fields is necessary for the reliable applications of their field effect transistors. Here, we explore the electrical breakdown phenomena originating from avalanche multiplication in MoS2 field effect transistors with different layer thicknesses and channel lengths. Modulating the band structure and bandgap energy in MoS2 allows the avalanche multiplication to be controlled by adjusting the number of stacking layers. This phenomenon could be observed in transition metal dichalcogenide semiconducting systems due to its quantum confinement effect on the band structure. The relationship between the critical electric field for avalanche breakdown and bandgap energy is well fitted to a power law curve in both monolayer and multilayer MoS2.", "author_names": [ "Jinsu Pak", "Yeonsik Jang", "Junghwan Byun", "Kyungjun Cho", "Taeyoung Kim", "jae-Keun Kim", "Barbara Yuri Choi", "Jiwon Shin", "Yongtaek Hong", "Seungjun Chung", "Takhee Lee" ], "corpus_id": 49562951, "doc_id": "49562951", "n_citations": 18, "n_key_citations": 0, "score": 0, "title": "Two Dimensional Thickness Dependent Avalanche Breakdown Phenomena in MoS2 Field Effect Transistors under High Electric Fields.", "venue": "ACS nano", "year": 2018 }, { "abstract": "We study the quantum nonlinear Hall effect in two dimensional (2D) materials with time reversal symmetry. When only one mirror line exists, a transverse charge current occurs in the second order response to an external electric field, as a result of the Berry curvature dipole in momentum space. Candidate 2D materials to observe this effect are two dimensional transition metal dichalcogenides (TMDCs) First, we use an ab initio based tight binding approach to demonstrate that monolayer {T}_{d} structure TMDCs exhibit a finite Berry curvature dipole. In the $1H$ and $1{T}\\ensuremath{ phase of TMDCs, we show the emergence of a finite Berry curvature dipole with the application of strain and an electrical displacement field, respectively.", "author_names": [ "Jhih-Shih You", "Shiang Fang", "Su-Yang Xu", "Efthimios Kaxiras", "Tony Low" ], "corpus_id": 119213528, "doc_id": "119213528", "n_citations": 69, "n_key_citations": 1, "score": 0, "title": "Berry curvature dipole current in the transition metal dichalcogenides family", "venue": "", "year": 2018 } ]

[ { "abstract": "Millimeter and terahertz wave photodetectors have long been of great interest due to a wide range of applications, but they still face challenges in detection performance. Here, we propose a new strategy for the direct detection of millimeter and terahertz wave photons based on localized surface plasmon polariton (SPP) induced non equilibrium electrons in antenna assisted subwavelength ohmic metal semiconductor metal (OMSM) structures. The subwavelength OMSM structure is used to convert the absorbed photons into localized SPPs, which then induce non equilibrium electrons in the structure, while the antenna increases the number of photons coupled into the OMSM structure. When the structure is biased and illuminated, the unidirectional flow of the SPP induced non equilibrium electrons forms a photocurrent. The energy of the detected photons is determined by the structure rather than the band gap of the semiconductor. The detection scheme is confirmed by simulation and experimental results from the devices, made of gold and InSb, and a room temperature noise equivalent power (NEP) of 1.5 x 10 13 W Hz 1/2 is achieved.The detection of terahertz and millimeter waves has many applications, but there are still limitations in their technical performance. Here, Tong et al. demonstrate the direct detection of long wavelength radiation through surface plasmon excitation and a corresponding improvement in detection performance.", "author_names": [ "Jinchao Tong", "Wei Zhou", "Yue Qu", "Zhengji Xu", "Zhiming Huang", "Dao Hua Zhang" ], "corpus_id": 22558719, "doc_id": "22558719", "n_citations": 28, "n_key_citations": 0, "score": 1, "title": "Surface plasmon induced direct detection of long wavelength photons", "venue": "Nature Communications", "year": 2017 }, { "abstract": "Abstract Over secretion of cortisol from the adrenal cortex is closely related to acute and chronic stress; thus, rapid and sensitive detection of cortisol in serum is of critical importance for preventing the progression of stress related diseases. The binding of a biological molecule to the surface of metallic nanoparticles changes the local refractive index and in turn induces a shift in the localized surface plasmon resonance (LSPR) wavelength. Utilizing this phenomenon, we designed a novel disposable LSPR based cuvette type sensor for detecting cortisol in serum. The developed cuvette type nanosensor consists primarily of an assembly of plastic unit sensors coated with gold nanoparticles on a single layer wherein cortisol conjugated bovine serum albumin (BSA) is immobilized. In this system, a redshift in LSPR wavelength is induced by the binding of cortisol antibody onto cortisol conjugated BSA immobilized on a gold nanoparticle surface in the nanosensor. In a competitive assay, the nanosensor could rapidly detect cortisol in both a PBS solution and serum (within 20 min) at concentrations ranging from 1 to 10,000 ng/mL (2.759 3 x 103 nmol/L) which is comparable to conventional enzyme linked immunosorbent assay (ELISA) which typically requires longer than 4 h and complex sample preparation. Thus, we demonstrated that the LSPR based nanosensor system developed in this study can provide a useful toolkit for a rapid, highly sensitive and reliable detection of cortisol hormone in a commercially available manner.", "author_names": [ "Jeong Jin-Woo", "Saji Uthaman", "Ji-young Lee", "Hyejin Hwang", "Gibum Kim", "Pil J Yoo", "Bruce D Hammock", "Christina S Kim", "Park Yeon-Su", "In-Kyu Park" ], "corpus_id": 103691185, "doc_id": "103691185", "n_citations": 16, "n_key_citations": 1, "score": 0, "title": "In direct localized surface plasmon resonance (LSPR) based nanosensors for highly sensitive and rapid detection of cortisol", "venue": "", "year": 2018 }, { "abstract": "We show femtosecond direct laser induced assembly of gold nanostructures with plasmon resonance band variable as a function of laser irradiation in a wide range of visible wavelengths. A system of 2 photon lithography is used to achieve site selectively controlled dewetting of a thin gold film into nanostructures in which size and shape are highly dependent on the laser power. Simultaneous measurements of localized surface plasmon resonance (LSPR) and surface enhanced Raman scattering (SERS) in the presence of various concentrations of trans 1,2 bis(4 pyridyl) ethylene (BPE) as target molecule are performed in order to highlight the relationship between structural dimensions, plasmonic effect, and detection activity. The resulting gold NPs exhibit high sensitivity as both LSPR and SERS sensors and allow the detection of picomolar concentrations of BPE with a SERS enhancement factor (SEF) of 1.33 x 109 and a linear detection range between 10 3 and 10 12 M.", "author_names": [ "Safi Jradi", "Lama Zaarour", "Zeinab Chehadi", "Suzanna Akil", "Jerome Plain" ], "corpus_id": 53742270, "doc_id": "53742270", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Femtosecond Direct Laser Induced Assembly of Monolayer of Gold Nanostructures with Tunable Surface Plasmon Resonance and High Performance Localized Surface Plasmon Resonance and Surface Enhanced Raman Scattering Sensing.", "venue": "Langmuir the ACS journal of surfaces and colloids", "year": 2018 }, { "abstract": "We experimentally demonstrate the uncooled detection of long wavelength infrared (IR) radiation by thermal surface plasmon sensing using an all optical readout format. Thermal infrared radiation absorbed by an IR sensitive material with high thermo optic coefficient coated on a metal grating creates a refractive index change detectable by the shift of the supported surface plasmon resonance (SPR) measured optically in the visible spectrum. The interface localization of SPR modes and optical readout allow for submicrometer thin film transducers and eliminate complex readout integrated circuits, respectively, reducing form factor, leveraging robust visible detectors, and enabling low cost imaging cameras. We experimentally present the radiative heat induced thermo optic action detectable by SPR shift through imaging of a thermal source onto a bulk metal grating substrate with IR absorptive silicon nitride coating. Toward focal plane array integration, a route to facile fabrication of pixelated metal grating structures by nanoimprint lithography is developed, where a stable polymer, parylene C, serves as an IR absorptive layer with a high thermo optic coefficient. Experimental detection of IR radiation from real thermal sources imaged at infinity is demonstrated by our nanoimprinted polymer SPR pixels with an estimated noise equivalent temperature difference of 21.9 K.", "author_names": [ "Brandon Hong", "Felipe Vallini", "Cheng-Yi Fang", "Amr Alasaad", "Yeshaiahu Fainman" ], "corpus_id": 206436705, "doc_id": "206436705", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Simple Nanoimprinted Polymer Nanostructures for Uncooled Thermal Detection by Direct Surface Plasmon Resonance Imaging.", "venue": "ACS applied materials interfaces", "year": 2017 }, { "abstract": "Abstract For the first time, plasmonic diffraction grating is implemented for the combined direct and epifluorescence based readout of assays in real time. This plasmonic structure serves for grating coupled surface plasmon resonance (SPR) monitoring of molecular binding induced changes in the refractive index. In parallel, it allows to simultaneously perform plasmonically enhanced fluorescence (PEF) analysis of affinity binding of molecules that are labeled with fluorophores. This configuration offers facile readout of e.g. magnetic nanoparticle enhanced assays which is not possible with more conventional Kretschmann geometry. The performance characteristics of this combined approach are discussed by using two types of assays. In the first assay a fluorophore labeled protein with a medium molecular weight of 55 kDa was affinity captured on the plasmonic sensor grating. The associated PEF signal in this assay showed a signal to noise ratio that was 140 fold higher compared to that of the SPR detection channel. In the second assay, extracellular vesicles were detected by using antibodies against CD81 attached to the plasmonic grating. These vesicles were pre concentrated by their coupling to magnetic nanoparticles with cholera toxin B chain. This assay exploited magnetic nanoparticles as labels enabling rapid collection of analyte at the sensor surface and for the enhancement of the SPR sensor response. In this case the label free SPR detection channel outperformed the fluorescence based detection, as the SPR signal to noise ratio was 2.4 fold higher than that of PEF.", "author_names": [ "Agnes T Reiner", "Stefan Fossati", "Jakub Dostalek" ], "corpus_id": 102539574, "doc_id": "102539574", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Biosensor platform for parallel surface plasmon enhanced epifluorescence and surface plasmon resonance detection", "venue": "", "year": 2018 }, { "abstract": "Conventional analysis of molecular interactions by surface plasmon resonance is achieved by the observation of optical density changes due to analyte binding to the ligand on the surface. Low molecular weight interaction partners are normally not detected. However, if a macromolecule such as DNA can extend beyond the evanescent field and analyte interaction results in a large scale contraction, then the refractive index changes due to the increasing amount of macromolecules close to the surface. In our proof of principle experiment we could observe the direct folding of long, human telomeric repeats induced by the small analyte potassium using surface plasmon resonance spectroscopy. This work demonstrates the feasibility of new evanescent field based biosensors that can specifically observe small molecule interactions.", "author_names": [ "Constanze Schlachter", "Fred Lisdat", "Marcus Frohme", "Volker A Erdmann", "Zoltan Konthur", "Hans Lehrach", "Jorn Glokler" ], "corpus_id": 42095580, "doc_id": "42095580", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Pushing the detection limits: the evanescent field in surface plasmon resonance and analyte induced folding observation of long human telomeric repeats.", "venue": "Biosensors bioelectronics", "year": 2012 }, { "abstract": "Small molecules or analytes present in trace level are difficult to be detected directly using conventional surface plasmon resonance (SPR) sensor, due to its small changes in the refractive index induced by the binding of these analytes on the sensor surface. In this paper, a new approach that combines SPR sensor technology with Fe3O4 magnetic nanoparticles (MNPs) assays is developed for directly detecting of deltamethrin in soybean. The Fe3O4 MNPs conjugated with antibodies specific to antigen serves as both labels for enhancing refractive index change due to the capture of target analyte, and \"vehicles\" for the rapid delivery of analyte from a sample solution to the sensor surface. Meanwhile, SPR direct detection format without Fe3O4 MNPs and gas chromatography (GC) analysis were conducted for detection of deltamethrin in soybean to demonstrate the amplification effect of Fe3O4 MNPs. A good linear relationship was obtained between SPR responses and deltamethrin concentrations over a range of 0.01 1 ng/mL with the lowest measurable concentration of 0.01 ng/mL. The results reveal that the detection sensitivity for deltamethrin was improved by 4 orders of magnitude compared with SPR direct detection format. The recovery of 95.5 119.8% was obtained in soybean. The excellent selectivity of the present biosensor is also confirmed by two kinds of pesticides (fenvalerate and atrazine) as controls. This magnetic separation and amplification strategy has great potential for detection of other small analytes in trace level concentration, with high selectivity and sensitivity by altering the target analyte capture agent labeled to the carboxyl coated Fe3O4 MNPs.", "author_names": [ "Xia Liu", "Lei Li", "Youqian Liu", "Xingbo Shi", "Wen-Jin Li", "Yang Yang", "Lu-Gang Mao" ], "corpus_id": 25501398, "doc_id": "25501398", "n_citations": 33, "n_key_citations": 1, "score": 0, "title": "Ultrasensitive detection of deltamethrin by immune magnetic nanoparticles separation coupled with surface plasmon resonance sensor.", "venue": "Biosensors bioelectronics", "year": 2014 }, { "abstract": "It's difficult to detect single nanoparticle and virus because their sizes are too tine, which is below 100nm. However, nano pollutants and virus in the water and atmospheric environment have a serious impact on human life. We present a method to detect the single nanoparticle and virus by direct imaging the surface plamon scattering induced by nanoparticle or virus. The schematic is shown in Figure 1. Experimentally, single 39nm polystyrene particle has been \"seen\" (as shown in Figure 2) and three viruses, e.g. T4 phage, PR8 influenza virus and EV71 enterovirus, have been detected in PBS buffer solution. This method is fast, high sensitivity, simple and low cost, which has a potential application to in situ monitor the water and atmospheric environment.", "author_names": [ "Xinchao Lu", "Hongyao Liu", "Xuqing Sun", "Yaqin Chen", "Wei Xiong" ], "corpus_id": 136134820, "doc_id": "136134820", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Fast detection to single nanoparticle and virus by using surface Plasmon scattering imaging", "venue": "", "year": 2016 }, { "abstract": "Light manipulation is vitally important for one dimensional semiconductor nanostructure based photodetectors which have great potential in future optoelectronic circuits, imaging technique, and light wave communication. In this paper, we reported a plasmonic gold nanoparticle (AuNP) decorated nano photodetector for green light sensing. It is found that the as fabricated device exhibits obvious increase in light absorption in the range from 400 to 550 nm, after functionalization of plasmonic AuNPs. Further device performance analysis reveals that the photocurrent of the plasmonic photodetector was increased by more than sevenfold, compared with that without coating. What is more, both responsivity and detectivity are found to increase as well. According to theoretical simulation based on the finite element method (FEM) the observed enhancement in device performance can be attributed to the surface plasmon induced direct electron injection from the metal nanoparticles to the semiconductor nanostructures.", "author_names": [ "Lin-Bao Luo", "Kun Zheng", "Caiwang Ge", "Yi-Feng Zou", "Rui Lu", "Yuan Wang", "Dan-dan Wang", "Tengfei Zhang", "Feng-xia Liang" ], "corpus_id": 124881846, "doc_id": "124881846", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Surface Plasmon Enhanced Nano photodetector for Green Light Detection", "venue": "Plasmonics", "year": 2015 }, { "abstract": "Cytotoxic T lymphocytes (CTL) recognize antigens as peptides associated with molecules of the major histocompatibility complex (MHC) The accurate characterization of antigenic peptides requires knowledge of how peptides bind to MHC molecules, and hence the conformational changes they can induce. Several reports have indicated that the conformation of the MHC class I molecule plays a role in T cell recognition. We therefore studied the interaction of a series of viral epitopes with HLA A2, A3, B7 and B8 molecules to determine how peptides could induce conformational changes in HLA molecules. This was done either directly with class I heavy chains in lysates of peptide loading deficient T2 cells, or with purified material from B EBV transformed cell lines. The peptide induced HLA conformations were assessed using monoclonal anti HLA antibodies (mAbs) and detected by surface plasmon resonance (SPR) Antigenic peptides specifically bound to the HLA molecule, even when assembly occurred in a mixed solution of HLA molecules. Distinct patterns of reactivity to a given peptide bound class I molecule were obtained with monomorphic and allele specific anti HLA mAbs.", "author_names": [ "F Hlavac", "Francine Connan", "Johan Hoebeke", "Jean Gerard Guillet", "Jeannine Choppin" ], "corpus_id": 13468880, "doc_id": "13468880", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Direct detection of peptide dependent HLA variability by surface plasmon resonance.", "venue": "Molecular immunology", "year": 1996 } ]

[ { "abstract": "Flexible electronic devices have attracted a great deal of attention in recent years due to their flexibility, reduced complexity and lightweight. Such devices can conformably attach themselves to any bendable surface and can possess diverse transduction mechanisms. Consequently, with continued emphasis on innovation and development, major technological breakthroughs have been achieved in this area. This review focuses on the advancements of using organic field effect transistors (OFETs) in flexible electronic applications in the past 10 years. In addition, to the above mentioned features, OFETs have multiple advantages such as low cost, readout integration, large area coverage, and power efficiency, which yield synergy. To begin with, we have introduced organic semiconductors (OSCs) followed by their applications in various device configurations and their mechanisms. Later, the use of OFETs in flexible sensor applications is detailed with multiple examples. Special attention is paid to discussing the effects induced on physical parameters of OFETs with respect to variations in external stimuli. The final section provides an outlook on the mechanical aspects of OSCs, activation and revival processes of sensory layers, small area analysis, and pattern recognition techniques for electronic devices.", "author_names": [ "Saravanan Yuvaraja", "Ali Nawaz", "Qian Liu", "Deepak P Dubal", "Sandeep Goud Surya", "Khaled Nabil Salama", "Prashant Sonar" ], "corpus_id": 218690264, "doc_id": "218690264", "n_citations": 41, "n_key_citations": 0, "score": 1, "title": "Organic field effect transistor based flexible sensors.", "venue": "Chemical Society reviews", "year": 2020 }, { "abstract": "Organic field effect transistors (OFETs) with hexagonal barium titanate nanocrystals (h BTNCs) in amorphous matrix as one of the bilayer dielectric systems have been fabricated on a highly flexible 10 mm thick poly(ethylene terephthalate) substrate. The device current and mobility remain constant up to a bending radius of 4 mm, which makes the substrate suitable for wearable e skin applications. h BTNC films are found to be highly temperature sensitive, and the OFETs designed based on this material showed ultraprecision measurement ~4.3 mK) low power ~1 mW at 1.2 V operating voltage) and ultrafast response ~24 ms) in sensing temperature over a range of 20 45 degC continuously. The sensors are highly stable around body temperature and work at various extreme conditions, such as under water and in solutions of different pH values and various salt concentrations. These properties make this sensor unique and highly suitable for various healthcare and other applications, wherein a small variation of temperature around this temperature range is required to be measured at an ultrahigh speed.", "author_names": [ "Suman Mandal", "Madhuchanda Banerjee", "Satyajit Roy", "Ajoy Mandal", "Arnab Ghosh", "Biswarup Satpati", "Dipak K Goswami" ], "corpus_id": 58604533, "doc_id": "58604533", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Organic Field Effect Transistor Based Ultrafast, Flexible, Physiological Temperature Sensors with Hexagonal Barium Titanate Nanocrystals in Amorphous Matrix as Sensing Material.", "venue": "ACS applied materials interfaces", "year": 2019 }, { "abstract": "Organic Field Effect Transistors (OFETs) are attracting a rising interest for the development of novel kinds of sensing platforms. In this paper, we report about a peculiar sensor device structure, namely Organic Charge Modulated Field Effect Transistor (OCMFET) capable of operating at low voltages and entirely fabricated with large area techniques, i.e. inkjet printing and chemical vapor deposition, that can be easily upscaled to an industrial size. Device fabrication is described, and statistical characterization of the basic electronic parameters is reported. As an effective benchmark for the application of large area fabricated OCMFET to the biomedical field, its combination with pyroelectric materials and compressible capacitors is discussed, in order to employ the proposed device as a temperature pressure sensor. The obtained sensors are capable to operate in conditions which are relevant in the biomedical field (temperature in the range of 18.5 50 degC, pressure in the range of 102 103 Pa) with reproducible and valuable performances, opening the way for the fabrication of low cost, flexible sensing platforms.", "author_names": [ "Stefano Lai", "Fabrizio Antonio Viola", "Piero Cosseddu", "Annalisa Bonfiglio" ], "corpus_id": 3612738, "doc_id": "3612738", "n_citations": 12, "n_key_citations": 1, "score": 0, "title": "Floating Gate, Organic Field Effect Transistor Based Sensors towards Biomedical Applications Fabricated with Large Area Processes over Flexible Substrates", "venue": "Sensors", "year": 2018 }, { "abstract": "A novel flexible lactate sensor based on organic field effect transistors (OFETs) is demonstrated. Because lactate is known as a biomarker for assessing our physical performance, wearable lactate sensors could contribute to the monitoring of human health conditions. The flexible and low voltage operatable OFET possesses an extended gate modified with enzymes and an osmium redox polymer for the lactate detection, meaning that the continuous measurement of lactate levels (0 10 mM) has been successfully achieved. We believe that insight obtained will open up opportunities for applying OFETs in wearable biosensors.", "author_names": [ "Tsukuru Minamiki", "Shizuo Tokito", "Tsuyoshi Minami" ], "corpus_id": 52089978, "doc_id": "52089978", "n_citations": 12, "n_key_citations": 0, "score": 0, "title": "Fabrication of a Flexible Biosensor Based on an Organic Field effect Transistor for Lactate Detection.", "venue": "Analytical sciences the international journal of the Japan Society for Analytical Chemistry", "year": 2019 }, { "abstract": "In this study, a novel approach to the fabrication of a multimodal temperature and force sensor on ultrathin, conformable and flexible substrates is presented. This process involves coupling a charge modulated organic field effect transistor (OCMFET) with a pyro/piezoelectric element, namely a commercial film of poly vinylene difluoride (PVDF) The proposed device is able to respond to both pressure stimuli and temperature variations, demonstrating the feasibility of the approach for the development of low cost, highly sensitive and conformable multimodal sensors. The overall thickness of the device is 1.2 mm, being thus able to conform to any surface (including the human body) while keeping its electrical performance. Furthermore, it is possible to discriminate between simultaneously applied temperature and pressure stimuli by coupling sensing surfaces made of poled and unpoled spin coated PVDF trifluoroethylene (PVDF TrFE, a PVDF copolymer) with OCMFETs. This demonstrates the possibility of creating multimodal sensors that can be employed for applications in several fields, ranging from robotics to wearable electronics.", "author_names": [ "Fabrizio Antonio Viola", "Andrea Spanu", "Pier Carlo Ricci", "Annalisa Bonfiglio", "Piero Cosseddu" ], "corpus_id": 43919843, "doc_id": "43919843", "n_citations": 56, "n_key_citations": 0, "score": 0, "title": "Ultrathin, flexible and multimodal tactile sensors based on organic field effect transistors", "venue": "Scientific Reports", "year": 2018 }, { "abstract": "Organic field effect transistors (OFETs) using the polymer as the active layer are being intensively developed for flexible electronics including the gas sensor. However, as same as the other kinds of OFET gas sensors, its selectivity is not quite good enough. As we all know, the interfaces, including semiconductor/semiconductor and semiconductor/dielectric, play important roles in gas sensing. In this work, we introduced additional non conjugated polymer into the polymer active layer, to modulate the selectivity of polymer based OFET gas sensors to a certain gas. As a result, we can get two kinds of high selective gas sensors based on single polymer OFETs. Both the detection limit, response and selectivity of ammonia and nitrogen dioxide were significantly improved with different non conjugated polymers, and the device cost was also reduced by a factor of eight as compared to that using pure polymer material. By analyzing the electrical characteristics of OFET sensors and combining with the intrinsic characteristic of the non conjugated polymers, we systematically studied the mechanism of the performance improvement.", "author_names": [ "Shijiao Han", "Zhirun Li", "Xinming Zhuang", "Junsheng Yu" ], "corpus_id": 139613092, "doc_id": "139613092", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Influence of polymer additional modulating layer on the selectivity performance of organic field effect transistor based gas sensor", "venue": "International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT)", "year": 2019 }, { "abstract": "Summary With the advent of the Internet of Things (IoT) era, flexible sensors are regarded as one of the most important technologies for the development of human friendly wearable devices. Organic field effect transistors (OFETs) based on conjugated polymers or small molecules are promising sensor platforms because they have various advantages, including high sensitivity, mechanical flexibility, and low cost fabrication processes. OFET based sensors enable continuous monitoring of external stimuli or target analytes with superior detection capabilities. This review describes the working principles and sensing mechanisms of various OFET based sensors, including chemical, biological, photo, pressure, and temperature sensors, and introduces the recent progress in this field. In addition, the technical challenges and future outlook of OFET based sensors for next generation flexible electronics are briefly discussed.", "author_names": [ "Yoon Ho Lee", "Moonjeong Jang", "Moo Yeol Lee", "O Young Kweon", "Joon Hak Oh" ], "corpus_id": 139134933, "doc_id": "139134933", "n_citations": 86, "n_key_citations": 0, "score": 0, "title": "Flexible Field Effect Transistor Type Sensors Based on Conjugated Molecules", "venue": "", "year": 2017 }, { "abstract": "Vertical organic field effect transistors (VOFETs) have been explored with a higher current density, a faster switch speed, and a better air stability than conventional OFETs, which dramatically enhance the capability of driving an AMOLED backplane. Unfortunately, the state of the art of the fabrication of solution processed VOFETs is still very complicated, which can only focus at a single cell level. In this work, with the assistance of the inkjet print, the fabrication process of a solution processed VOFET was significantly simplified, and a solution processed VOFET array was fabricated for the first time, which exhibited excellent device performance and outstanding mechanical stability. More importantly, the VOFET arrays exhibited excellent photodetector properties, and a flexible image sensor based on VOFET arrays with multipoint visible photodetection and image recognition was demonstrated for the first time. Therefore, this novel process dramatically simplified the VOFET device fabrication process and a successfully realized array, which promoted the commercialization of VOFET and showed great potential in flexible display, multifunctional sensors, and wearable integrated circuits.", "author_names": [ "Yuan Fang", "Xiaomin Wu", "Shuqiong Lan", "Jianfeng Zhong", "Dawei Sun", "Huipeng Chen", "Tailiang Guo" ], "corpus_id": 206486026, "doc_id": "206486026", "n_citations": 33, "n_key_citations": 0, "score": 0, "title": "Inkjet Printed Vertical Organic Field Effect Transistor Arrays and Their Image Sensors.", "venue": "ACS applied materials interfaces", "year": 2018 }, { "abstract": "", "author_names": [ "" ], "corpus_id": 115675981, "doc_id": "115675981", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Flexible and Wearable Sensors Based on Organic Field Effect Transistor Platforms", "venue": "", "year": 2015 }, { "abstract": "Here, we report flexible thermal sensors based on organic field effect transistors (OFETs) that are fabricated using polymeric channel and gate insulating layers on flexible polymer film substrates. Poly(3 hexylthiophene) and poly(methyl methacrylate) were used as the channel and gate insulating layers, respectively, whereas indium tin oxide coated poly(ethylene naphthalate) films (thickness 130 mm) were employed as the flexible substrates. Aluminum coated polymer films were attached on top of the channel parts in the flexible OFETs to block any influence by light illumination. The present flexible OFET based thermal sensors exhibited typical p type transistor characteristics at a temperature range of 25 100 degC, while the hole mobility of devices was linearly increased with the temperature. The drain current could be amplified at various temperatures by adjusting the gate and drain voltages. In particular, stable sensing performances were measured during the repeated approaching/retreating cycle with a heat source. The flexible OFET thermal sensors attached on human fingers could sense heat from human fingers as well as from approaching objects.", "author_names": [ "Myeonghun Song", "Jooyeok Seo", "Hwajeong Kim", "Youngkyoo Kim" ], "corpus_id": 116380918, "doc_id": "116380918", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Flexible Thermal Sensors Based on Organic Field Effect Transistors with Polymeric Channel/Gate Insulating and Light Blocking Layers", "venue": "ACS omega", "year": 2017 } ]

[ { "abstract": "This paper provides a historical review of the literature on the effects of radiation induced displacement damage in semiconductor materials and devices. Emphasis is placed on effects in technologically important bulk silicon and silicon devices. The primary goals are to provide a guide to displacement damage literature, to offer critical comments regarding that literature in an attempt to identify key findings, to describe how the understanding of displacement damage mechanisms and effects has evolved, and to note current trends. Selected tutorial elements are included as an aid to presenting the review information more clearly and to provide a frame of reference for the terminology used. The primary approach employed is to present information qualitatively while leaving quantitative details to the cited references. A bibliography of key displacement damage information sources is also provided.", "author_names": [ "J R Srour", "Cheryl J Marshall", "Paul W Marshall" ], "corpus_id": 39593833, "doc_id": "39593833", "n_citations": 548, "n_key_citations": 32, "score": 1, "title": "Review of displacement damage effects in silicon devices", "venue": "", "year": 2003 }, { "abstract": "In this paper, we review the radiation damage issues caused by displacement damage in silicon sensors operating in the harsh radiation environments of high energy physics experiments. The origin and parameterization of the changes in the macroscopic electrical sensor properties such as depletion voltage, leakage current, and charge collection efficiency as a function of fluence of different particles, annealing time, and annealing temperature are reviewed. The impact of impurities in the silicon base crystal on these changes is discussed, revealing their effects on the degradation of the sensor properties. Differences on how segmented and nonsegmented devices are affected and how device engineering can improve radiation hardness are explained and characterization techniques used to study sensor performance and the electric field distribution inside the irradiated devices are outlined. Finally, recent developments in radiation hardening and simulation techniques using technology computer aided design modeling are given. This paper concludes with radiation damage issues in presently operating experiments and gives an outlook of radiation hardened technologies to be used in the future upgrades of the Large Hadron Collider and beyond.", "author_names": [ "Michael Moll" ], "corpus_id": 52050199, "doc_id": "52050199", "n_citations": 55, "n_key_citations": 2, "score": 0, "title": "Displacement Damage in Silicon Detectors for High Energy Physics", "venue": "IEEE Transactions on Nuclear Science", "year": 2018 }, { "abstract": "A review of radiation induced displacement damage effects in semiconductor devices is presented, with emphasis placed on silicon technology. The history of displacement damage studies is summarized, and damage production mechanisms are discussed. Properties of defect clusters and isolated defects are addressed. Displacement damage effects in materials and devices are considered, including effects produced in silicon particle detectors, visible imaging arrays, and solar cells. Additional topics examined include NIEL scaling, carrier concentration changes, random telegraph signals, radiation hardness assurance, and simulation methods for displacement damage. Areas needing further study are noted.", "author_names": [ "J R Srour", "James W Palko" ], "corpus_id": 1522815, "doc_id": "1522815", "n_citations": 122, "n_key_citations": 5, "score": 0, "title": "Displacement Damage Effects in Irradiated Semiconductor Devices", "venue": "IEEE Transactions on Nuclear Science", "year": 2013 }, { "abstract": "High energy radiation produces defect complexes in semiconductor materials which reduce minority carrier lifetime, change majority carrier density, and reduce mobility. Most of the experimental data on semiconductors and semiconductor devices has been taken using high energy neutrons. Recent research has shown that this data can be extrapolated to other high energy radiation such as protons, electrons, alpha particles and gamma rays by normalizing to the energy going into atomic processes. Minority carrier lifetime is the most sensitive electronic property of silicon in the neutron environment. The degradation of minority carrier lifetime results in changes in semiconductor device properties such as current gain, storage time, saturation voltage and sink current. Carrier removal is the next most important characteristic of displacement damage and it causes a decrease in carrier mobility and an increase in resistivity. The dependence of these basic semiconductor properties on neutron fluence is introduced into device models such as SPICE and the resulting radiation inclusive model permits quantitative determination of device parameters as a function of neutron fluence.<ETX>", "author_names": [ "George C Messenger" ], "corpus_id": 110458608, "doc_id": "110458608", "n_citations": 121, "n_key_citations": 7, "score": 0, "title": "A summary review of displacement damage from high energy radiation in semiconductors and semiconductor devices", "venue": "RADECS 91 First European Conference on Radiation and its Effects on Devices and Systems", "year": 1991 }, { "abstract": "This review concerns radiation effects in silicon Charge Coupled Devices (CCDs) and CMOS active pixel sensors (APSs) both of which are used as imagers in the visible region. Permanent effects, due to total ionizing dose and displacement damage, are discussed in detail, with a particular emphasis on the space environment. In addition, transient effects are briefly summarized. Implications for ground testing, effects mitigation and device hardening are also considered. The review is illustrated with results from recent ground testing.", "author_names": [ "Gordon R Hopkinson", "A Mohammadzadeh" ], "corpus_id": 109955547, "doc_id": "109955547", "n_citations": 19, "n_key_citations": 0, "score": 0, "title": "RADIATION EFFECTS IN CHARGE COUPLED DEVICE (CCD) IMAGERS AND CMOS ACTIVE PIXEL SENSORS", "venue": "", "year": 2004 }, { "abstract": "The dependence of displacement damage effects in silicon charge coupled devices on the bias conditions during proton irradiation has been assessed. The devices have been fully characterized for dark signal increase, charge transfer degradation and the generation of random telegraph signals. A 5 to 10% higher degradation rate for all these parameters has been seen when unbiased during irradiation, under conditions typically used for a proton irradiation campaign, compared with the case when operating the devices during the irradiation. Room temperature annealing has been investigated and shows a bias dependence for all parameters tested. A reverse annealing behavior of bulk dark signal and random telegraph signals following illumination is reported for the first time. Both the annealing and reverse annealing observations may, in part, be attributed to the behavior of the trivacancy.", "author_names": [ "Mark Stanford Robbins", "Luis Gomez Rojas" ], "corpus_id": 41273030, "doc_id": "41273030", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "An Assessment of the Bias Dependence of Displacement Damage Effects and Annealing in Silicon Charge Coupled Devices", "venue": "IEEE Transactions on Nuclear Science", "year": 2013 }, { "abstract": "We report on a study of the sensitivity of silicon MEMS to proton radiation and mitigation strategies. MEMS can degrade due to ionizing radiation (electron hole pair creation) and non ionizing radiation (displacement damage) such as electrons, trapped and solar protons, or cosmic rays, typically found in a space environment. Over the past few years there has been several reports on the effects of ionizing radiation in silicon MEMS, with failure generally linked to trapped charge in dielectrics. However there is near complete lack of studies on displacement damage effects in silicon MEMS: how does silicon change mechanically due to proton irradiation? We report on an investigation on the susceptibility of 50 mm thick SOI based MEMS resonators to displacement damages due to proton beams, with energies from 1 to 60 MeV, and annealing of this damage. We measure ppm changes on the Young's modulus and Poisson ratio by means of accurately monitoring the resonant frequency of devices in vacuum using a Laser Doppler Vibrometer. We observed for the first time an increase (up to 0.05% of the Young's modulus of single crystal silicon electromagnetically actuated micromirrors after exposure to low energy protons (1 4 MeV) at high absorbed doses 100 Mrad (Si) This investigation will contribute to a better understanding of the susceptibility of silicon based MEMS to displacement damages frequently encountered in a space radiation environment, and allow appropriated design margin and shielding to be implemented.", "author_names": [ "Joao Gomes", "Herbert R Shea" ], "corpus_id": 6872567, "doc_id": "6872567", "n_citations": 22, "n_key_citations": 3, "score": 0, "title": "Displacement damage effects in silicon MEMS at high proton doses", "venue": "MOEMS MEMS", "year": 2011 }, { "abstract": "The concept of non ionizing energy loss (NIEL) has been demonstrated to be a successful approach to describe the displacement damage effects in silicon materials and devices. However, some discrepancies exist in the literature between experimental damage factors and theoretical NIELs. 60Co gamma rays having a low NIEL are an interesting particle source that can be used to validate the NIEL scaling approach. This paper presents different 60Co gamma ray NIEL values for silicon targets. They are compared with the radiation induced increase in the thermal generation rate of carriers per unit fluence. The differences between the different models, including one using molecular dynamics, are discussed.", "author_names": [ "Elsayed E Allam", "Christophe Inguimbert", "Andrew Meulenberg", "Anouar Jorio", "I Zorkani" ], "corpus_id": 125462037, "doc_id": "125462037", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Gamma non ionizing energy loss: Comparison with the damage factor in silicon devices", "venue": "", "year": 2018 }, { "abstract": "With the growing interest to explore Jupiter's moons, technologies with +10 Mrad(Si) tolerance are now needed, to survive the Jovian environment. Conductive bridging random access memory (CBRAM) is a nonvolatile memory that has shown a high tolerance to total ionizing dose (TID) However, it is not well understood how CBRAM behaves in an energetic ion environment where displacement damage (DD) effects may also be an issue. In this paper, the response of CBRAM to 100 keV Li, 1 MeV Ta, and 200 keV Si ion irradiations is examined. Ion bombardment was performed with increasing fluence steps until the CBRAM devices failed to hold their programed state. The TID and DD dose (DDD) at the fluence of failure were calculated and compared against tested ion species. Results indicate that failures are more highly correlated with TID than DDD. DC cycling tests were performed during 100 keV Li irradiations and evidence was found that the mobile Ag ion supply diminished with increasing fluence. The cycling results, in addition to prior 14 MeV neutron work, suggest that DD may play a role in the eventual failure of a CBRAM device in a combined radiation environment.", "author_names": [ "Jennifer Taggart", "Robin B Jacobs-Gedrim", "Michael Mclain", "Hugh J Barnaby", "Edward S Bielejec", "W Hardy", "Matthew J Marinella", "Michael N Kozicki", "Keith E Holbert" ], "corpus_id": 58670394, "doc_id": "58670394", "n_citations": 1, "n_key_citations": 1, "score": 0, "title": "Failure Thresholds in CBRAM Due to Total Ionizing Dose and Displacement Damage Effects", "venue": "IEEE Transactions on Nuclear Science", "year": 2019 }, { "abstract": "The total ionizing dose effects in silicon based semiconductor devices (SDs) and integrated circuits (ICs) under conditions of low dose rate irradiation typical of space applications are surveyed. The mechanism of radiation induced charge buildup in the dielectric of MOS structures and at the semiconductor/dielectric interface is considered. In addition, the nature of defects in the Si/SiO2 structure responsible for these processes is analyzed. The specific features of annealing the charge trapped in a dielectric during irradiation and also of interface traps (surface states, SSs) are shown. The peculiarities of the degradation of MOS and bipolar devices are considered for low dose rate irradiation conditions typical of space applications. It is shown that under low dose rate irradiation, MOS devices are prone to time dependent effects which are determined by the kinetics of charge buildup and annealing in the Si/SiO2 structure, whereas bipolar devices may be susceptible to true dose rate effects. The main experimental methods of modeling low dose rate effects during accelerated tests of silicon devices and integrated circuits are surveyed. The necessity of using fundamentally different experimental approaches in modeling the time dependent effects in MOS devices and the true dose rate effects in bipolar devices and integrated circuits is demonstrated.", "author_names": [ "Konstantin I Tapero" ], "corpus_id": 195334639, "doc_id": "195334639", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Low Dose Rate Effects in Silicon Based Devices and Integrated Circuits: A Review", "venue": "", "year": 2018 } ]

[ { "abstract": "We herein present a first principles formulation of the Green Kubo method that allows the accurate assessment of the phonon thermal conductivity of solid semiconductors and insulators in equilibrium ab initio molecular dynamics calculations. Using the virial for the nuclei, we propose a unique ab initio definition of the heat flux. Accurate size and time convergence are achieved within moderate computational effort by a robust, asymptotically exact extrapolation scheme. We demonstrate the capabilities of the technique by investigating the thermal conductivity of extreme high and low heat conducting materials, namely, Si (diamond structure) and tetragonal ZrO_{2}", "author_names": [ "Christian Carbogno", "Rampi Ramprasad", "Matthias Scheffler" ], "corpus_id": 26727094, "doc_id": "26727094", "n_citations": 47, "n_key_citations": 0, "score": 1, "title": "Ab Initio Green Kubo Approach for the Thermal Conductivity of Solids.", "venue": "Physical review letters", "year": 2017 }, { "abstract": "The Green Kubo theory of thermal transport has long be considered incompatible with modern simulation methods based on electronic structure theory, because it is based on such concepts as energy density and current, which are ill defined at the quantum mechanical level. Besides, experience with classical simulations indicates that the estimate of heat transport coefficients requires analysing molecular trajectories that are more than one order of magnitude longer than deemed feasible using ab initio molecular dynamics. In this paper we report on recent theoretical advances that are allowing one to overcome these two obstacles. First, a general gauge invariance principle has been established, stating that thermal conductivity is insensitive to many details of the microscopic expression for the energy density and current from which it is derived, thus permitting to establish a rigorous expression for the energy flux from Density Functional Theory, from which the conductivity can be computed in practice. Second, a novel data analysis method based on the statistical theory of time series has been proposed, which allows one to considerably reduce the simulation time required to achieve a target accuracy on the computed conductivity. These concepts are illustrated in detail, starting from a pedagogical introduction to the Green Kubo theory of linear response and transport, and demonstrated with a few applications done with both classical and quantum mechanical simulation methods.", "author_names": [ "Stefano Baroni", "Riccardo Bertossa", "Loris Ercole", "Federico Grasselli", "Aris Marcolongo" ], "corpus_id": 56003369, "doc_id": "56003369", "n_citations": 20, "n_key_citations": 1, "score": 0, "title": "Heat transport in insulators from ab initio Green Kubo theory", "venue": "", "year": 2018 }, { "abstract": "", "author_names": [ "Stefano Baroni" ], "corpus_id": 100524241, "doc_id": "100524241", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Car and Parrinello meet Green and Kubo: simulating atomic heat transport from equilibrium ab initio molecular dynamics", "venue": "", "year": 2017 }, { "abstract": "Abstract The structural and dynamical properties of liquid alloys are directly related to their solidification process, and consequently to the properties of as cast solid alloys. Ab initio molecular dynamics is a powerful tool that can be used to study both of these factors. Thus, in this work, TiZrNbHfTa and VZrMoHfW liquid equiatomic alloys, exclusively consisting of transition metal (TM) elements, are studied using ab initio molecular dynamics via the CP2K software package; partial pair correlation functions (PPCFs) are calculated, and their parameters are discussed. The calculated densities of these alloys are shown to be close to the ideal mixture densities. The analysis of the PPCFs is performed to predict the single phase high entropy alloy (HEA) formation. The obtained results agree with the semi empirical phase formation rules. The diffusivities of the elements are calculated using the Green Kubo relation and the mean square displacement (MSD) plot. The diffusivity is shown to decrease as the atomic mass and radius increase. The scattering process of different types of atoms in TiZrNbHfTa and VZrMoHfW are also discussed.", "author_names": [ "I A Balyakin", "Boris Gelchinski", "Andrej A Rempel" ], "corpus_id": 203556780, "doc_id": "203556780", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Ab initio molecular dynamics study of TiZrNbHfTa and VZrMoHfW liquid alloys", "venue": "", "year": 2019 }, { "abstract": "Transport properties of permalloy doped with V, Co, Pt, and Au are explored via ab initio calculations. The Kubo Bastin formula is evaluated within the fully relativistic Korringa Kohn Rostoker Green function formalism. Finite temperature effects are treated by means of the alloy analogy model. It is shown that the fact that the host is disordered and not crystalline has a profound effect on how the conductivities characterizing the anomalous Hall effect and the spin Hall effect depend on the dopant concentration. Several relationships between quantities characterizing charge and spin transport are highlighted. The decrease of the longitudinal charge conductivity with increasing doping depends on the dopant type, following the sequence Co Au Pt V. The dependence of the anomalous Hall and spin Hall conductivities on the dopant concentration is found to be non monotonic. Introducing a finite temperature changes the overall trends significantly. The theoretical results are compared with available experimental data.", "author_names": [ "Ondrej Sipr", "S Wimmer", "S Mankovsky", "Hubert Ebert" ], "corpus_id": 202572943, "doc_id": "202572943", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Transport properties of doped permalloy via ab initio calculations: Effect of host disorder", "venue": "", "year": 2019 }, { "abstract": "Here, given the unique optical properties of LiF, it is often used as an observation window in high temperature and pressure experiments; hence, estimates of its transmission properties are necessary to interpret observations. Since direct measurements of the thermal conductivity of LiF at the appropriate conditions are difficult, we resort to molecular simulation methods. Using an empirical potential validated against ab initio phonon density of states, we estimate the thermal conductivity of LiF at high temperatures (1000 4000 K) and pressures (100 400 GPa) with the Green Kubo method. We also compare these estimates to those derived directly from ab initio data. To ascertain the correct phase of LiF at these extreme conditions, we calculate the (relative) phase stability of the B1 and B2 structures using a quasiharmonic ab initio model of the free energy. We also estimate the thermal conductivity of LiF in an uniaxial loading state that emulates initial stages of compression in high stress ramp loading experiments and show the degree of anisotropy induced in the conductivity due to deformation.", "author_names": [ "Rosemary E Jones", "D K Ward" ], "corpus_id": 118879555, "doc_id": "118879555", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Estimates of crystalline LiF thermal conductivity at high temperature and pressure by a Green Kubo method", "venue": "", "year": 2016 }, { "abstract": "The experimental unexpected large Seebeck coefficient in SrTiO3 (STO) cannot be reproduced theoretically by the conventional Bloch Boltzmann transport with electron phonon coupling calculated perturbatively, indicating a failure of Fermi liquid picture in STO and ill treatment of polaronic states. Starting from many body interaction picture, the polaronic states can be precisely described by the method of cumulant expansion of retarded Green's function. By applying Kubo Greenwood method, we found that the mysterious Seebeck coefficient can be fully described by a combination of polarons and Fermi liquid. The coexistence of two types of quasi particles are attributed to the multi band nature of t2g orbitals. Polarons are formed from the one with heavier electronic effective mass, while the one with lighter effective mass is renormalized into Fermi liquid quasi particles. Our method provides a practical way to study the effect of strong electron phonon coupling on transport properties from first principles.", "author_names": [ "Jichang Ren", "Jian-Sheng Wang" ], "corpus_id": 118931029, "doc_id": "118931029", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Origin of unexpected large Seebeck effect in SrTiO3: nonperturbative polaron study from ab initio cumulant expansion.", "venue": "", "year": 2018 }, { "abstract": "The electronic structure and magnetic properties of rocksalt type CaC compound are studied by means of first principles calculations. The B1 type calcium monocarbide is a metastable, nearly half metallic ferromagnetic compound, with a magnetic moment of 1.81 m B/f.u. and a negative Fermi level spin polarization of 50% The estimated Curie temperature exceeds the room temperature. The electronic, magnetic and spin polarized transport properties of CaC/MgS/CaC (0 0 1) heterostructures are investigated by using a first principles Green's function technique for layered structures in conjunction with the Kubo Landauer formalism. The magnetism of CaC (0 0 1) electrodes is robust while the Fermi level spin polarization of interfacial CaC layers at CaC/MgS (0 0 1) interfaces increases over the bulk value. The localized states formed at CaC/MgS (0 0 1) interfaces strongly enhance the minority spin ferromagnetic state conductance. The current spin polarization reaches values as high as 99% Very large magnetoresistance ratios, above 104% are in evidence. The highly magnetoresistive effect observed for CaC/MgS/CaC (0 0 1) heterojunctions together with the robust ferromagnetism of CaC (0 0 1) electrodes make this system attractive in the context of spin electronics.", "author_names": [ "Petru Vlaic", "Emil Burzo", "Karel Carva" ], "corpus_id": 100298114, "doc_id": "100298114", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Spin polarized transport utilizing d 0 ferromagnetism: an ab initio study of CaC/MgS/CaC (0 0 1) heterojunctions", "venue": "", "year": 2015 }, { "abstract": "Quantum simulation methods based on density functional theory are currently deemed to be unfit to cope with atomic thermal transport in materials within the Green Kubo formalism. In contrast with this belief, we derive an expression for the adiabatic energy flux from density functional theory, that permits the ab initio simulation of atomic thermal transport using equilibrium molecular dy namics. The resulting thermal conductivity is shown to be unaffected by the inherent ill definedness of quantum mechanical energy densities and currents. Our new methodology is demonstrated by comparing results from ab initio and classical molecular dynamics simulations of a model liquid Argon system, for which accurate inter atomic potentials are derived by the force matching method, and finally applied to compute the thermal conductivity of heavy water at ambient conditions.", "author_names": [ "Aris Marcolongo" ], "corpus_id": 100891245, "doc_id": "100891245", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Theory and ab initio simulation of atomic heat transport", "venue": "", "year": 2014 }, { "abstract": "We develop a formalism for the evaluation of conduction eigenchannels of atomic sized contacts from first principles. The multiple scattering Korringa Kohn Rostoker Green's function method is combined with the Kubo linear response theory. Solutions of the eigenvalue problem for the transmission matrix are proven to be identical to eigenchannels introduced by Landauer and B\\\"uttiker. Applications of the method are presented by studying ballistic electron transport through Cu, Pd, Ni, and Co single atom contacts. We show in detail how the eigenchannels are classified in terms of irreducible representations of the symmetry group of the system as well as by orbital contributions when the channels' wave functions are projected on the contact atom.", "author_names": [ "Alexei Bagrets", "N Papanikolaou", "Ingrid Mertig" ], "corpus_id": 118849471, "doc_id": "118849471", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Conduction eigenchannels of atomic sized contacts: Ab initio KKR Green's function formalism.", "venue": "", "year": 2007 } ]

[ { "abstract": "Sensory, motor and cognitive operations involve the coordinated action of large neuronal populations across multiple brain regions in both superficial and deep structures. Existing extracellular probes record neural activity with excellent spatial and temporal (sub millisecond) resolution, but from only a few dozen neurons per shank. Optical Ca2+ imaging offers more coverage but lacks the temporal resolution needed to distinguish individual spikes reliably and does not measure local field potentials. Until now, no technology compatible with use in unrestrained animals has combined high spatiotemporal resolution with large volume coverage. Here we design, fabricate and test a new silicon probe known as Neuropixels to meet this need. Each probe has 384 recording channels that can programmably address 960 complementary metal oxide semiconductor (CMOS) processing compatible low impedance TiN sites that tile a single 10 mm long, 70 x 20 mm cross section shank. The 6 x 9 mm probe base is fabricated with the shank on a single chip. Voltage signals are filtered, amplified, multiplexed and digitized on the base, allowing the direct transmission of noise free digital data from the probe. The combination of dense recording sites and high channel count yielded well isolated spiking activity from hundreds of neurons per probe implanted in mice and rats. Using two probes, more than 700 well isolated single neurons were recorded simultaneously from five brain structures in an awake mouse. The fully integrated functionality and small size of Neuropixels probes allowed large populations of neurons from several brain structures to be recorded in freely moving animals. This combination of high performance electrode technology and scalable chip fabrication methods opens a path towards recording of brain wide neural activity during behaviour.", "author_names": [ "James Jun", "Nicholas A Steinmetz", "Joshua H Siegle", "Daniel J Denman", "Marius Bauza", "brian barbarits", "Albert K Lee", "Costas A Anastassiou", "Alexandru Andrei", "Cagatay Aydin", "Mladen Barbic", "Timothy J Blanche", "Vincent Bonin", "Joao Couto", "Barundeb Dutta", "Sergey L Gratiy", "Diego A Gutnisky", "Michael Hausser", "Bill Karsh", "Peter Ledochowitsch", "Carolina Mora Lopez", "Catalin Mitelut", "Silke Musa", "Michael Okun", "Marius Pachitariu", "Jan Putzeys", "P Dylan Rich", "Cyrille Rossant", "Wei-lung Sun", "Karel Svoboda", "Matteo Carandini", "Kenneth D Harris", "Christof Koch", "John O'Keefe", "Timothy D Harris" ], "corpus_id": 205262002, "doc_id": "205262002", "n_citations": 896, "n_key_citations": 32, "score": 1, "title": "Fully integrated silicon probes for high density recording of neural activity", "venue": "Nature", "year": 2017 }, { "abstract": "Modern optogenetic experiments require high spatio temporal resolution stimulation deep in brain tissue. Implantable optoelectrical neural probes with integrated recording electrodes and photonic devices offer unique opportunities for simultaneous electrical recording and optical stimulation of neural activity. Micro light emitting diodes (uLEDs) have been used for optical stimulation. However, such uLEDs are mostly fabricated on rigid substrates such as silicon and sapphire. Flexible, polymer substrates are preferred for realizing neural probes that reduce damage to brain tissue. Commercial off the shelf LED chips have been packaged in polymer substrates; however, the prohibitively large sizes of such LED chips limit the density of the probes and process scalability. Here, we demonstrate a novel monolithic design in which recording electrodes and GaN uLEDs (30 um x 30 um) are realized directly in a flexible, biocompatible Parylene C substrate. Due to its biocompatibility and compliance, Parylene C is widely used as insulation or substrate in neural probes. We demonstrate one dimensional and two dimensional individually addressable uLED arrays that emit blue light at the wavelength of 453 nm for stimulation of Channelrhodopsin 2 (ChR2) with output intensities greater than 15 mW/mm2, well above the threshold for stimulation of ChR2. High density (400 uLEDs/mm2) two dimensional electrode arrays are realized on a 3.5 cm x 920 um flexible probe shank.", "author_names": [ "Jay W Reddy", "Ibrahim Kimukin", "Elias Towe", "Maysamreza Chamanzar" ], "corpus_id": 159043404, "doc_id": "159043404", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Flexible, Monolithic, High Density uLED Neural Probes for Simultaneous Optogenetics Stimulation and Recording*", "venue": "2019 9th International IEEE/EMBS Conference on Neural Engineering (NER)", "year": 2019 }, { "abstract": "This paper reports on a novel high density CMOS based silicon microprobe array for intracortical recording applications. In contrast to existing systems, CMOS multiplexing units are integrated directly on the slender, needle like probe shafts. Single shaft probes and four shaft combs have been realized with 188 and 752 electrodes, respectively, with a pitch of 40 mm arranged in two columns along 4 mm long probe shafts. Rather than performing a mechanical translation of the probe shaft relative to the brain tissue to optimize the distance between electrodes and neurons, the electrode position is adjusted by electronically switching between the different electrodes along the shaft. The paper presents the probe concept, the CMOS circuitry design, the applied post CMOS fabrication process, and the assembled probe systems.", "author_names": [ "Karsten Seidl", "Stanislav Herwik", "Tom Torfs", "H Pereira Neves", "Oliver Paul", "Patrick Ruther" ], "corpus_id": 24141203, "doc_id": "24141203", "n_citations": 71, "n_key_citations": 7, "score": 0, "title": "CMOS Based High Density Silicon Microprobe Arrays for Electronic Depth Control in Intracortical Neural Recording", "venue": "Journal of Microelectromechanical Systems", "year": 2011 }, { "abstract": "We report a scalable method to monolithically integrate microscopic light emitting diodes (mLEDs) and recording sites onto silicon neural probes for optogenetic applications in neuroscience. Each mLED and recording site has dimensions similar to a pyramidal neuron soma, providing confined emission and electrophysiological recording of action potentials and local field activity. We fabricated and implanted the four shank probes, each integrated with 12 mLEDs and 32 recording sites, into the CA1 pyramidal layer of anesthetized and freely moving mice. Spikes were robustly induced by 60 nW light power, and fast population oscillations were induced at the microwatt range. To demonstrate the spatiotemporal precision of parallel stimulation and recording, we achieved independent control of distinct cells 50 mm apart and of differential somato dendritic compartments of single neurons. The scalability and spatiotemporal resolution of this monolithic optogenetic tool provides versatility and precision for cellular level circuit analysis in deep structures of intact, freely moving animals.", "author_names": [ "Fan Wu", "Eran Stark", "Pei Cheng Ku", "Kensall D Wise", "Gyorgy Buzsaki", "Euisik Yoon" ], "corpus_id": 4964470, "doc_id": "4964470", "n_citations": 232, "n_key_citations": 11, "score": 0, "title": "Monolithically Integrated mLEDs on Silicon Neural Probes for High Resolution Optogenetic Studies in Behaving Animals", "venue": "Neuron", "year": 2015 }, { "abstract": "The evolution of tissue penetrating probes for high density deep brain recording of in vivo neural activity is limited by the level of electronic integration on the probe shaft. As the number of electrodes increases, conventional devices need either a large number of interconnects at the base of the probe or allow only a reduced number of electrodes to be read out simultaneously [1,2] Active probes are used to improve the signal quality and reduce parasitic effects in situ, but still need to route these signals from the electrodes to a base where the readout electronics is located on a large area [3,4] In this work, we present a modular and scalable architecture of a needle probe, which, instead of routing or prebuffering noise sensitive analog signals along the shaft, integrates analog to digital conversion under each electrode in an area of 70x70mm2. The design eliminates the need for any additional readout circuitry at the top of the probe and connects with a digital 4 wire interface. The presented reconfigurable 11.5mm probe features a constant width of 70mm and thickness of 50mm from top to bottom for minimal tissue damage with 144 integrated recording sites and can be fully immersed in tissue for deep brain recording applications.", "author_names": [ "Daniel DeDorigo", "Christian Moranz", "Hagen Graf", "Maximilian Marx", "Boyu Shui", "Matthias Kuhl", "Yiannos Manoli" ], "corpus_id": 3838682, "doc_id": "3838682", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "A fully immersible deep brain neural probe with modular architecture and a delta sigma ADC integrated under each electrode for parallel readout of 144 recording sites", "venue": "2018 IEEE International Solid State Circuits Conference (ISSCC)", "year": 2018 }, { "abstract": "Extracellular electrode arrays can reveal the neuronal network correlates of behavior with single cell, single spike, and sub millisecond resolution. However, implantable electrodes are inherently invasive, and efforts to scale up the number and density of recording sites must compromise on device size in order to connect the electrodes. Here, we report on silicon based neural probes employing nanofabricated, high density electrical leads. Furthermore, we address the challenge of reading out multichannel data with an application specific integrated circuit (ASIC) performing signal amplification, band pass filtering, and multiplexing functions. We demonstrate high spatial resolution extracellular measurements with a fully integrated, low noise 64 channel system weighing just 330 mg. The on chip multiplexers make possible recordings with substantially fewer external wires than the number of input channels. By combining nanofabricated probes with ASICs we have implemented a system for performing large scale, high density electrophysiology in small, freely behaving animals that is both minimally invasive and highly scalable.", "author_names": [ "Jiangang Du", "Timothy J Blanche", "Reid R Harrison", "Henry A Lester", "Sotiris C Masmanidis" ], "corpus_id": 15226568, "doc_id": "15226568", "n_citations": 220, "n_key_citations": 17, "score": 0, "title": "Multiplexed, High Density Electrophysiology with Nanofabricated Neural Probes", "venue": "PloS one", "year": 2011 }, { "abstract": "Brain activity is highly structured within local microcircuits and brain wide networks, involving exquisite coordination across multiple brain regions in both superficial and deep structures [1] To understand how brain represents, transforms and communicates information requires simultaneously monitoring distributed neural activity at brain wide scale with single neuron resolution [2] Extracellular electrical recording probes can detect spikes from individual neurons within milliseconds, however, their contact site numbers are limited and only a few dozen neurons per probe can be recorded [3,4] More contacts can be achieved with probe array coupled to external amplification and multiplexing electronics. However, too many transmission wires and large form factor hardware make it impractical to use in freely moving rodents [5] Optical approaches such as Ca imaging cover multiple areas across spatial scales, but cannot identify the precise timing of spikes of neuronal activity due to their low temporal resolution [2] Simultaneously monitoring neural activities across multiple brain regions at neuronal scale with high temporal resolution is still challenging. To meet this challenge, Jun and colleagues [6] have developed a silicon based probe called Neuropixels containing 960 sites on a single shank, which can simultaneously record the activity of more than 200 individual neurons. What's more, the length of the recording shank as long as 10 mm enables recording from multiple brain regions simultaneously, and even the deepest structures of a mouse brain can be accessed. The dense and extensive recording sites on a single probe was achieved using a custom 130 nm CMOS fabrication process. This process allowed Jun and colleagues to place 960 sites on a single shank with 70 mm x 20 mm cross section. The recording sites are arranged in a checkerboard pattern with 4 columns (Fig. 1a) The authors also integrated low noise analogue amplifiers, multiplexers and digitizers into the probe base (Fig. 1b) with the same CMOS process. According to the cuttingedge electronics, 384 of the 960 total sites on the shank can be addressed simultaneously by user programmable switches, allowing active recording sites to be altered after implantation. Data from all 384 channels coul d be digitized and compressed in the probe base, realizing a digital output stream transmitted via a single thin cable, enabling the device to be compatible with long term attachment to small animals with natural behaviour. A key element in the Neuropixels probe is the recording site material. The typical material (PEDOT coated gold [7] used to make recording contacts is not compatible with the electronic fabrication process of Neuropixels. The authors developed porous titanium nitride (TiN) for the recording site material (Fig. 1c) They found that probes based on TiN performed as well as those made of conventional materials when implanted in animals for 8 weeks. What's more, sites made of TiN are compatible with the CMOS processing, ensuring scalable fabrication of the Neuropixels probes at low cost [6] The long recording length and abundant recording sites of Neuropixels probes allowed researchers to obtain electrophysiological measurements across a large spatial extent. As an example, the authors inserted a probe into the brain of an awake, head fixed mouse, targeting the primary visual cortex and the lateral posterior nucleus of the thalamus. Because the probe records activity with the same spatial resolution along the entire shank, the data can be conveniently displayed as images with each site represented as a \"pixel\" Using these images, structural boundaries can be visualized using simple measures of neural activity, such as firing rates or signal amplitude", "author_names": [ "Bo Liang", "Xuesong Ye" ], "corpus_id": 140032497, "doc_id": "140032497", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Towards high density recording of brain wide neural activity", "venue": "Science China Materials", "year": 2018 }, { "abstract": "Recent demand and initiatives in brain research have driven significant interest toward developing chronically implantable neural interface systems with high spatiotemporal resolution and spatial coverage extending to the whole brain. Electroencephalography based systems are noninvasive and cost efficient in monitoring neural activity across the brain, but suffer from fundamental limitations in spatiotemporal resolution. On the other hand, neural spike and local field potential (LFP) monitoring with penetrating electrodes offer higher resolution, but are highly invasive and inadequate for long term use in humans due to unreliability in long term data recording and risk for infection and inflammation. Alternatively, electrocorticography (ECoG) promises a minimally invasive, chronically implantable neural interface with resolution and spatial coverage capabilities that, with future technology scaling, may meet the needs of recently proposed brain initiatives. In this paper, we discuss the challenges and state of the art technologies that are enabling next generation fully implantable high density ECoG interfaces, including details on electrodes, data acquisition front ends, stimulation drivers, and circuits and antennas for wireless communications and power delivery. Along with state of the art implantable ECoG interface systems, we introduce a modular ECoG system concept based on a fully encapsulated neural interfacing acquisition chip (ENIAC) Multiple ENIACs can be placed across the cortical surface, enabling dense coverage over wide area with high spatiotemporal resolution. The circuit and system level details of ENIAC are presented, along with measurement results.", "author_names": [ "Sohmyung Ha", "Abraham Akinin", "Jiwoong Park", "Chul Kim", "Hui Wang", "Christoph Maier", "Patrick P Mercier", "Gert Cauwenberghs" ], "corpus_id": 24999749, "doc_id": "24999749", "n_citations": 54, "n_key_citations": 8, "score": 0, "title": "Silicon Integrated High Density Electrocortical Interfaces", "venue": "Proceedings of the IEEE", "year": 2017 }, { "abstract": "This paper presents a needle shaped neural probe which integrates an incremental <inline formula> <tex math notation=\"LaTeX\"\\Delta \\Sigma /tex math>/inline formula> ADC under each electrode in an area of <inline formula> <tex math notation=\"LaTeX\"$70\\times 70\\\\mu \\text{m}\\mathrm{ 2} /tex math>/inline formula> The modular architecture avoids global routing of noise sensitive neural signals and connects with a digital four wire interface. The re configurable 5.6/11.5 mm needle enables parallel readout of all 64/144 integrated recording sites and features a constant width and thickness of <inline formula> <tex math notation=\"LaTeX\"$70\\times 50\\\\mu \\text{m}\\mathrm{ 2} /tex math>/inline formula> from top to bottom allowing to be fully implanted for deep brain monitoring applications. Platinum or iridium oxide electrodes can be deposited in a custom post CMOS process. The functionality of the recording system is demonstrated in an <italic>in vivo</italic> setup. The noise performance of 6.02 <inline formula> <tex math notation=\"LaTeX\"\\mu \\text{V}_{\\text {rms} /tex math>/inline formula> for LFP signals (1 300 Hz) and 10.46 <inline formula> <tex math notation=\"LaTeX\"\\mu \\text{V}_{\\text {rms} /tex math>/inline formula> for AP signals (300 Hz 10 kHz) is obtained at a power consumption of 39.14 <inline formula> <tex math notation=\"LaTeX\"\\mu \\text{W} /tex math>/inline formula> per recording site.", "author_names": [ "Daniel De Dorigo", "Christian Moranz", "Hagen Graf", "Maximilian Marx", "Daniel Wendler", "Boyu Shui", "Abdalrahman Sayed Herbawi", "Matthias Kuhl", "Patrick Ruther", "Oliver Paul", "Yiannos Manoli" ], "corpus_id": 53232593, "doc_id": "53232593", "n_citations": 29, "n_key_citations": 3, "score": 0, "title": "Fully Immersible Subcortical Neural Probes With Modular Architecture and a Delta Sigma ADC Integrated Under Each Electrode for Parallel Readout of 144 Recording Sites", "venue": "IEEE Journal of Solid State Circuits", "year": 2018 }, { "abstract": "To understand how function arises from the interactions between neurons, it is necessary to use methods that allow the monitoring of brain activity at the single neuron, single spike level and the targeted manipulation of the diverse neuron types selectively in a closed loop manner. Large scale recordings of neuronal spiking combined with optogenetic perturbation of identified individual neurons has emerged as a suitable method for such tasks in behaving animals. To fully exploit the potential power of these methods, multiple steps of technical innovation are needed. We highlight the current state of the art in electrophysiological recording methods, combined with optogenetics, and discuss directions for progress. In addition, we point to areas where rapid development is in progress and discuss topics where near term improvements are possible and needed.", "author_names": [ "Gyorgy Buzsaki", "Eran Stark", "Antal Berenyi", "Dion Khodagholy", "Daryl R Kipke", "Euisik Yoon", "Kensall D Wise" ], "corpus_id": 16286284, "doc_id": "16286284", "n_citations": 239, "n_key_citations": 8, "score": 0, "title": "Tools for probing local circuits: high density silicon probes combined with optogenetics", "venue": "Neuron", "year": 2015 } ]

[ { "abstract": "We report a method to form multifunctional polymer coatings through simple dip coating of objects in an aqueous solution of dopamine. Inspired by the composition of adhesive proteins in mussels, we used dopamine self polymerization to form thin, surface adherent polydopamine films onto a wide range of inorganic and organic materials, including noble metals, oxides, polymers, semiconductors, and ceramics. Secondary reactions can be used to create a variety of ad layers, including self assembled monolayers through deposition of long chain molecular building blocks, metal films by electroless metallization, and bioinert and bioactive surfaces via grafting of macromolecules.", "author_names": [ "Haeshin Lee", "Shara M Dellatore", "William M Miller", "Phillip B Messersmith" ], "corpus_id": 206509131, "doc_id": "206509131", "n_citations": 6612, "n_key_citations": 116, "score": 1, "title": "Mussel Inspired Surface Chemistry for Multifunctional Coatings", "venue": "Science", "year": 2007 }, { "abstract": "", "author_names": [ "Haeshin Lee" ], "corpus_id": 97873978, "doc_id": "97873978", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Multifunctional Coatings Mussel Inspired Surface Chemistry for", "venue": "", "year": 2007 }, { "abstract": "Abstract Mussel inspired surface modification has been received great attention due to the universal adhesive properties of catechols for fabrication of multifunctional coatings, especially for gluing hydrophilic polymers to fabricate underwater superoleophobic materials utilizing in oil/water separation. Despite the extensive research carried out on this topic, the similarity and discrepancy between catecholamine and catecholic amino acid on surface modification and post functionalization have not been fully addressed yet. In this work, underwater superoleophobic surfaces have been successfully developed by a two step dip coating method with mussel inspired coatings and subsequent zwitterionic sulfobetaine methacrylate (SBMA) grafting onto stainless steel meshes and used in oil/water separation. Here, dopamine and 3,4 dihydroxy L phenylalanine were both served as mussel adhesives. More specifically, small molecule zwitterion rather than polyzwitterion was functionalized onto mussel inspired coatings to minimize the effect of surface topography on surface wettability. The modified surfaces were characterized by scanning electron microscopy (SEM) atomic force microscopy (AFM) and contact angle measurements to observe the surface morphology, estimate the surface roughness, and evaluate the wettability, respectively. It showed that SBMA modified meshes with polydopamine (PDA) or poly(3,4 dihydroxy L phenylalanine) (PDOPA) layer possessed quite different surface roughness, while both presented excellent oil repellency in water with underwater oil contact angles of 153deg 160deg, indicating a less dependence on surface roughness. Although by using the small molecule as the hydrophilic functionalized groups, the as prepared meshes exhibited good self cleaning and oil/water separation performance (separation efficiency >98% for hexane and >97% for soybean oil) and outstanding recyclability with 98% separation efficiency after 30 cycles. This method provides insight into different properties of polycatechols and simplifies the fabrication process through the use of small molecule zwitterion rather than zwitterionic polymer. Besides, the modified meshes also exhibited excellent stability for long term use. The resulting underwater superoleophobicity and robust self cleaning ability promise an ideal candidate for oil/water separation and oil contamination restriction.", "author_names": [ "Xiaolu Chen", "Yadan Zhai", "Xia Han", "Honglai Liu", "Ying Hu" ], "corpus_id": 133497968, "doc_id": "133497968", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Surface chemistry dominated underwater superoleophobic mesh with mussel inspired zwitterionic coatings for oil/water separation and self cleaning", "venue": "Applied Surface Science", "year": 2019 }, { "abstract": "Heparin, an important polysaccharide, has been widely used for coatings of cardiovascular devices because of its multiple biological functions including anticoagulation and inhibition of intimal hyperplasia. In this study, surface heparinization of a commonly used 316L stainless steel (SS) was explored for preparation of a multifunctional vascular stent. Dip coating of the stents in an aqueous solution of dopamine and hexamethylendiamine (HD) (PDAM/HD) was presented as a facile method to form an adhesive coating rich in primary amine groups, which was used for covalent heparin immobilization via active ester chemistry. A heparin grafting density of about 900 ng/cm(2) was achieved with this method. The retained bioactivity of the immobilized heparin was confirmed by a remarkable prolongation of the activated partial thromboplastin time (APTT) for about 15 s, suppression of platelet adhesion, and prevention of the denaturation of adsorbed fibrinogen. The Hep PDAM/HD also presented a favorable microenvironment for selectively enhancing endothelial cell (EC) adhesion, proliferation, migration and release of nitric oxide (NO) and at the same time inhibiting smooth muscle cell (SMC) adhesion and proliferation. Upon subcutaneous implantation, the Hep PDAM/HD exhibited mitigated tissue response, with thinner fibrous capsule and less granulation formation compared to the control 316L SS. This number of unique functions qualifies the heparinized coating as an attractive alternative for the design of a new generation of stents.", "author_names": [ "Ying Yang", "Pengkai Qi", "Feng Wen", "Xiangyang Li", "Qin Xia", "Manfred F Maitz", "Zhilu Yang", "Ru Shen", "Qiufen Tu", "Nan Huang" ], "corpus_id": 5511478, "doc_id": "5511478", "n_citations": 88, "n_key_citations": 0, "score": 0, "title": "Mussel inspired one step adherent coating rich in amine groups for covalent immobilization of heparin: hemocompatibility, growth behaviors of vascular cells, and tissue response.", "venue": "ACS applied materials interfaces", "year": 2014 }, { "abstract": "After more than four billion years of evolution, nature has created a large number of fascinating living organisms, which show numerous peculiar structures and wonderful properties. Nature can provide sources of plentiful inspiration for scientists to create various materials and devices with special functions and uses. Since Messersmith proposed the fabrication of multifunctional coatings through mussel inspired chemistry, this field has attracted considerable attention for its promising and exiciting applications. Polydopamine (PDA) an emerging soft matter, has been demonstrated to be a crucial component in mussel inspired chemistry. In this review, the recent developments of PDA for mussel inspired surface modification are summarized and discussed. The biomedical applications of PDA based materials are also highlighted. We believe that this review can provide important and timely information regarding mussel inspired chemistry and will be of great interest for scientists in the chemistry, materials, biology, medicine and interdisciplinary fields.", "author_names": [ "Meiying Liu", "Guangjian Zeng", "Ke Wang", "Qing Wan", "Lei Tao", "Xiaoyong Zhang", "Yen Wei" ], "corpus_id": 35107757, "doc_id": "35107757", "n_citations": 352, "n_key_citations": 2, "score": 0, "title": "Recent developments in polydopamine: an emerging soft matter for surface modification and biomedical applications.", "venue": "Nanoscale", "year": 2016 }, { "abstract": "Mussel inspired chemistry has been broadly exploited for multifunctional coatings in the surface modification of applied materials. Polyphenols are ubiquitous in plant tissues and far less expensive than polydopamine for mussel inspired chemistry. Herein, we report a facile and effective method to modify porous membranes via the co deposition of catechol (CCh) and polyethyleneimine (PEI) The membrane structures and properties were investigated by ATR/FTIR, XPS, FESEM, zeta potential, water contact angle and pure water flux measurements. The results reveal that the membranes deposited with a CCh PEI mass ratio of 1:0.25 show excellent hydrophilicity, ultrahigh water permeation flux and distinguished surface charges. These membranes were used to decolorize anionic dye solutions during filtration with superior removal efficiencies of over 99% Moreover, they have good reusability over repeated operations with a simple regeneration process.", "author_names": [ "Wen-Ze Qiu", "Hao-Cheng Yang", "Ling-Shu Wan", "Zhi-kang Xu" ], "corpus_id": 93161437, "doc_id": "93161437", "n_citations": 107, "n_key_citations": 1, "score": 0, "title": "Co deposition of catechol/polyethyleneimine on porous membranes for efficient decolorization of dye water", "venue": "", "year": 2015 }, { "abstract": "Kang et al. \"Bioinspired single bacterial cell force spectroscopy' Langmuir, 2009, 25(17):9656 9659. Ku et al. \"General functionalization route for cell adhesion on non wetting surfaces' Biomaterials, 2010.31:2535 2541. Lee et al. \"Mussel inspired surface chemistry for multifunctional coatings\" Science, 2007, 318(5849) 1 10. Ku et al. \"Human endothelial cell growth on mussel inspiried nanofiber scaffold for vascular tissue engineering' Biomaterials, 2010, 31:9431 9437. Ozgen et al. \"Evaluation of long term transport ability of a bioartificial renal tubule device using LLC PK1 cells' Nephrol Dial Transplant, 2004, 19:2198 2207. The 5' SBE International Conference on Bioengineering and Nano technology, Singapore: Poster presentation on Aug. 3, 2010. Pre senter: Ming Ni. The 5\" SBE International Conference on Bioengineering and Nano technology, Singapore: Oral conference presentation on Aug. 4. 2010. Presenter: Daniele Zink. Seminar on Sep. 13, 2010 European Conference on Biomaterials, Tampere Finland. Presenter: Ming Ni. The 5' SBE International Conference on Bioengineering and Nano technology, Singapore: IBN Labtour on Aug. 3, 2010. Presenter: Daniele Zink. Doraiswamy, Matrix assisted pulsed laser evaporation of DOPA modified poly(ethylene glycol) thin films, J. Adhesion Sci Technol (2007) p. 1 13. Humes et al. Initial clinical results of the bioartificial kidney containing human cells in ICU patients with acute renal failure. Kidney Int 66:1578 1588 (2004) Ku et al. General functionalization route for cell adhesion on non wetting surfaces, Biomaterials, 31:2535 2541 (2010) Lee et al. Mussel Inspired Surface Chemistry for Multifunctional Coatings, Science, 318:426 (2007) Lee et al. A reversible wet/dry adhesive inspired by mussels and geckos, Nature, 448:338 (Jul. 19, 2007) Lee et al. Single molecule mechanics of mussel adhesion, PNAS, 103, 12999 13003 (Aug. 29, 2006) Ni et al. Characterization of membrane materials and membrane coatings for bioreactor units of bioartificial kidneys, Biomaterials, 32, pp. 1465 1476, 2011. (Continued)", "author_names": [ "Daniele Zink" ], "corpus_id": 208056282, "doc_id": "208056282", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "MEMBRANES OF BOARTIFICIAL, KIDNEYS", "venue": "", "year": 2017 }, { "abstract": "Abstract Plant inspired polyphenols are capable of forming substrate independent coatings for versatile functionalization via oxidative self polymerization in an alkalescent aqueous solution. However, shortcomings like low uniformity and lengthy reaction times discourage their large scale implementations. In this work, we report a benign surface modification method for the highly effective, inexpensive construction of catechol (CA) coatings using sodium periodate (SP) as a trigger. Compared with recent progress in polyphenol coatings, our strategy achieved by far the fastest superhydrophilic modification rate ever reported. UV vis spectroscopy, atomic force microscopy (AFM) and ellipsometry are used to gain insights into the reaction kinetics of oxidant triggered polymerization and deposition of CA. SP assisted CA films with good homogeneity were efficiently deposited on various dense and porous substrates. Ultimately, the unprecedentedly superhydrophilic/underwater superoleophobic coating layer was applied on the initially hydrophobic polyvinylidene fluoride (PVDF) membrane, endowing the porous membrane with extremely high pure water permeability, favorable heavy metal adsorption ability, and outstanding oil/water separation performance. Due to the chemical versatility of CA, we envision that this novel coating technique holds significant potentials in tailoring the surface properties of different materials for a wide range of applications.", "author_names": [ "Yulan Chen", "Qingxia Liu" ], "corpus_id": 105752200, "doc_id": "105752200", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "Oxidant induced plant phenol surface chemistry for multifunctional coatings: Mechanism and potential applications", "venue": "", "year": 2019 }, { "abstract": "Mussel inspired chemistry, as a powerful tool to manipulate material properties, has been widely studied and implemented in surface engineering of a variety of materials for multipurpose functionalization. With the rapid development of this field, more flexible and efficient modification strategies for surface engineering and application modes have been developed recently. It is therefore critical to update the broader scientific community on the important advances in this interdisciplinary field. Here, we summarize recent progress in mussel inspired chemistry and its emerging applications in water remediation. The reaction and adhesion mechanisms of polydopamine, as well as its chemical and physical properties, are discussed. The functionalization strategies are categorized into post functionalization, co deposition, and pre modification, and the roles of mussel inspired surface coatings are highlighted in filtration, adsorbing, and catalytic materials as well as the burgeoning area of photothermal distillation materials.", "author_names": [ "Zhenxing Wang", "Hao Yang", "Fang He", "Shaoqin Peng", "Yuexiang Li", "Lu Shao", "Seth B Darling" ], "corpus_id": 199247713, "doc_id": "199247713", "n_citations": 104, "n_key_citations": 0, "score": 0, "title": "Mussel Inspired Surface Engineering for Water Remediation Materials", "venue": "Matter", "year": 2019 }, { "abstract": "In this work, surface functionalized microcapsules from porous carbon nanospheres (PCNs) were successfully prepared by mussel inspired chemistry with polydopamine (PDA) and metal free photoinduced electron transfer atom transfer radical polymerization (PET ATRP) These functional microcapsules are introduced into self healing hydrogels to enhance its mechanical strength. The PCNs synthesized by a simple soft template method are mixed with linseed oil (LO) for loading of the biomass healing agent and the microcapsules are first prepared by coating PDA. PDA coatings were used to immobilize ATRP initiator for initiating 4 vinylpyridine (4VP) on the surface of microcapsules by PET ATRP. Using these functional microcapsules, the self healing efficiency was about 92.5% after 4 hrs at ambient temperature and the healed tensile strength can be held at 2.5 MPa with a fracture strain of 625.2% All results indicated that the surface functionalized microcapsules for self healing hydrogels have remarkable biocompatibility and mechanical properties.", "author_names": [ "Dechao Fan", "Guang-lin Wang", "Anyao Ma", "Wenxiang Wang", "Hou Chen", "Liangjiu Bai", "Huawei Yang", "Donglei Wei", "Lixia Yang" ], "corpus_id": 206498784, "doc_id": "206498784", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Surface Engineering of Porous Carbon for Self Healing Nanocomposite Hydrogels by Mussel inspired Chemistry and PET ATRP.", "venue": "ACS applied materials interfaces", "year": 2019 } ]

[ { "abstract": "Summary We introduce Sb2Si2Te6 as a high performance thermoelectric material. Single crystal X ray diffraction analysis indicates that Sb2Si2Te6 has a layered two dimensional structure with Sb3+ cations and [Si2Te6]6 units as building blocks adopting the Fe2P2Se6 structure type. Sb2Si2Te6 is a direct band gap semiconductor with valence band maximum and conduction band minimum at the Z point in the Brillouin zone, where the band is doubly degenerate. Polycrystalline bulk pellets of Sb2Si2Te6 with randomly packed grains exhibit an intrinsically high thermoelectric figure of merit ZT of ~1.08 at 823 K. We then create a cellular nanostructure with ultrathin Si2Te3 nanosheets covering the Sb2Si2Te6 grains, which act as a hole transmitting electron blocking filter and at the same time cause extra phonon scattering. This dual function of the cellular nanostructure achieves an ultralow thermal conductivity value of ~0.29 Wm 1K 1 and a high ZT value of ~1.65 at 823 K for Sb2Si2Te6, along with a high average ZT value of ~0.98.", "author_names": [ "Yubo Luo", "Songting Cai", "Shiqiang Hao", "Florian Pielnhofer", "Ido Hadar", "Zhong-Zhen Luo", "Jianwei Xu", "Christopher Wolverton", "Vinayak P Dravid", "Arno Pfitzner", "Qingyu Yan", "Mercouri G Kanatzidis" ], "corpus_id": 212816492, "doc_id": "212816492", "n_citations": 27, "n_key_citations": 0, "score": 1, "title": "High Performance Thermoelectrics from Cellular Nanostructured Sb2Si2Te6", "venue": "", "year": 2020 }, { "abstract": "Thermoelectric energy conversion from waste heat sources is expected to play a crucial role in determining the world energy landscape through efficient thermal energy utilization and management. The thermoelectric performance of a material critically depends on its electrical conductivity and Seebeck coefficient. The electronic structure plays a pivotal role in determining both these parameters, electrical conductivity and Seebeck coefficient, in a material and, therefore, in turn, dominantly controls the material's thermoelectric performance. For example, a common feature among most of the known high performance thermoelectric materials is that they are heavily doped degenerate semiconductors and have large band degeneracy. Therefore, it is essential to improve our understanding and manipulation capabilities of the electronic structure in a material. Intensive research on thermoelectric materials has led to various novel electronic structure modulation strategies, such as valence band convergence, resonant level, and employment of various low dimensional electronic features. These strategies play a critical role in the recent developments of various high performance thermoelectric materials, such as PbTe, SnTe, SnSe, and GeTe. In this Perspective, we have discussed various electronic structure modulation strategies and their recent developments with a brief background of the underlying ideas.", "author_names": [ "Moinak Dutta", "Tanmoy Ghosh", "Kanishka Biswas" ], "corpus_id": 218805617, "doc_id": "218805617", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Electronic structure modulation strategies in high performance thermoelectrics", "venue": "", "year": 2020 }, { "abstract": "Abstract Thermoelectric materials with efficient heat energy conversion have been widely considered as potential electrical energy sources. Herein we propose an anion exchanged porous SnTe nanosheets (NSs) as a high performance thermoelectric material with ultra low thermal conductivity. The solution phase reaction mechanisms for porous SnTe NSs are proposed, and the reaction conditions are carefully manipulated in order to determine the optimal morphology and excellent thermoelectric performance. The porous SnTe NSs, which consist of extremely small nanoparticles of only ~3 nm in size with defective shapes, lead to a substantial reduction in the lattice thermal conductivity and a higher Seebeck coefficient compared to bulk SnTe, caused by the introduced nanointerfaces, pores and defects. An impressive ZT of ~1.1 at 923 K is achieved without atomic doping process, which is as many as ~2.8 times higher than that of bulk SnTe. This proposed strategy provides an insight to represent an unconventional method for the production of the porous SnTe NSs that can potentially be employed in practical high performance thermoelectric applications.", "author_names": [ "Hyun Ju", "Jooheon Kim" ], "corpus_id": 225154441, "doc_id": "225154441", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Anion exchanged porous SnTe nanosheets for ultra low thermal conductivity and high performance thermoelectrics", "venue": "", "year": 2020 }, { "abstract": "This review discusses recent developments and current research in high performance bulk thermoelectric materials, comprising nanostructuring, mesostructuring, band alignment, band engineering and synergistically defining key strategies for boosting the thermoelectric performance. To date, the dramatic enhancements in the figure of merit achieved in bulk thermoelectric materials have come either from the reduction in lattice thermal conductivity or improvement in power factors, or both of them. Here, we summarize these relationships between very large reduction of the lattice thermal conductivity with all scale hierarchical architecturing, large enhanced Seebeck coefficients with intra matrix electronic structure engineering, and control of the carrier mobility with matrix/inclusion band alignment, which enhance the power factor and reduce the lattice thermal conductivity. The new concept of hierarchical compositionally alloyed nanostructures to achieve these effects is presented. Systems based on PbTe, PbSe and PbS in which spectacular advances have been demonstrated are given particular emphasis. A discussion of future possible strategies is aimed at enhancing the thermoelectric figure of merit of these materials.", "author_names": [ "Li-dong Zhao", "Vinayak P Dravid", "Mercouri G Kanatzidis" ], "corpus_id": 98166227, "doc_id": "98166227", "n_citations": 626, "n_key_citations": 7, "score": 0, "title": "The panoscopic approach to high performance thermoelectrics", "venue": "", "year": 2014 }, { "abstract": "Abstract The search for new thermoelectric materials has been of great interest in recent years because thermoelectrics offers useful applications in next generation vehicles that can directly convert waste heat to electricity. Two dimensional (2D) tetradymites with M2X3 compounds, in which M (Bi) and X (Te, Se, S) are a group V metal and group VI anion, respectivety, are theoretically investigated in this study. Their energy bands are characterized by small energy gaps, high group velocities, small effective masses, nonparabolic bands and multi valleys convergence at near the center of the Brillouin zone, which are favorable conditions for high power factor with the optimum power factor values can be up to 0.20 0.25 W/mK2 at room temperature. Moreover, the 2D M2X3 contains heavy atomic masses and high polarizability of some chemical bonds, leading to small group velocities of phonons and anharmonic phonon behavior that produce an intrinsic lattice thermal conductivity as low as 1.5 2.0 W/mK at room temperature. We find that by mixtures of M and X atoms, such as Bi2Te2Se, the power factor further increases whereas the lattice thermal conductivity decreases. This design gives a high figure of merit of the p type 2D Bi2Te2Se from 1.4 to 2.0 at operating temperature within 300 500 K.", "author_names": [ "Nguyen Tuan Hung", "Ahmad Ridwan Tresna Nugraha", "Riichiro Saito" ], "corpus_id": 139914014, "doc_id": "139914014", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Designing high performance thermoelectrics in two dimensional tetradymites", "venue": "Nano Energy", "year": 2019 }, { "abstract": "Lead chalcogenides and their alloys belong at the heart of thermoelectrics due to their large thermoelectric figure of merit (zT) However, recent research has shown a limitation in the use of lead (Pb) based materials due to their toxicity and efforts have been made to produce non toxic analogues of lead chalcogenides. Tin chalcogenides have been predicted to be promising for this purpose due to their unique electronic structure and phonon dispersion properties. Here, we discuss the journey of tin chalcogenides in the field of thermoelectrics and topological materials with the main emphasis on the bonding, crystal structures, electronic band structures, phonon dispersion and thermoelectric properties. The thermal transport properties of tin chalcogenides are explained based on lattice dynamics, where resonant bonding and local structural distortion play an important role in creating lattice anharmonicity, thereby lowering the lattice thermal conductivity. Since thermoelectric and topological materials, especially topological insulators and topological crystalline insulators, share similar material features, such as a narrow band gap, heavy constituent elements and significant spin orbit coupling, we have discussed the thermoelectric properties of several topological tin chalcogenides from a chemistry perspective. This feature article serves as a useful reference for researchers who strive to improve the properties of tin chalcogenides and advance the field of thermoelectric and topological materials.", "author_names": [ "Ananya Banik", "Subhajit Roychowdhury", "Kanishka Biswas" ], "corpus_id": 13667475, "doc_id": "13667475", "n_citations": 45, "n_key_citations": 0, "score": 0, "title": "The journey of tin chalcogenides towards high performance thermoelectrics and topological materials.", "venue": "Chemical communications", "year": 2018 }, { "abstract": "Dramatic enhancements in the figure of merit have been obtained in bulk thermoelectric materials by doping, band engineering, and nanostructuring. Especially, in p type thermoelectrics, high figure of merits near 2.0 have been reported in a few papers through the reduction in lattice thermal conductivity and the advancement in power factors. However, there exists no report on the n type systems showing high figure of merits because of their intrinsically low Seebeck coefficients. Here, we demonstrate that a nanostructured bulk n type thermoelectric material that was assembled by sintering spinodally decomposed lead chalcogenide nanoparticles having a composition of PbSe0.5Te0.5 reaches a high figure of merit of 1.85. The spinodally decomposed nanoparticles permit our thermoelectric material to have extremely low lattice thermal conductivity and a high power factor as a result of nanostructuring, electronic optimization, insertion of an impurity phase and phase change in local areas. We propose that this interesting concept would be one of the promising approaches that overcome limitation arising from the fact that most parameters in the figure of merit are closely correlated.", "author_names": [ "Min-Seok Kim", "Woojin Lee", "Ki Hyun Cho", "Jae-Pyoung Ahn", "Yun Mo Sung" ], "corpus_id": 206703665, "doc_id": "206703665", "n_citations": 28, "n_key_citations": 1, "score": 0, "title": "Spinodally Decomposed PbSe PbTe Nanoparticles for High Performance Thermoelectrics: Enhanced Phonon Scattering and Unusual Transport Behavior.", "venue": "ACS nano", "year": 2016 }, { "abstract": "Abstract As an earth abundant material, PbS, has been paid extensive attention in the thermoelectric community. The high lattice thermal conductivity of PbS indicates there is room left to further improve thermoelectric performance of PbS. In this system we aimed to reduce the lattice thermal conductivity through nanostructuring grain sizes, which was processed by mechanical alloying followed by spark plasma sintering. We found that the lattice thermal conductivity can be reduced from ~1.5 W m 1 K 1 at 723 K for PbS ingot to as low as ~0.50 W m 1 K 1 for the PbS with nano scale grain sizes, as a result, a ZT value of 0.80 at 723 K was achieved for 1.0% PbCl 2 doped PbS with the second phases of Bi 2 S 3 (Sb 2 S 3 SrS, CaS) These results indicate that PbS is a robust alternative of PbTe and PbSe for medium temperature thermoelectric applications.", "author_names": [ "Cheng Chang", "Yu Xiao", "Xiao Zhang", "Yan-Ling Pei", "Fu Li", "Shulan Ma", "Bifei Yuan", "Y Liu", "Sheng-Kai Gong", "Li-dong Zhao" ], "corpus_id": 137637495, "doc_id": "137637495", "n_citations": 28, "n_key_citations": 0, "score": 0, "title": "High performance thermoelectrics from earth abundant materials: Enhanced figure of merit in PbS through nanostructuring grain size", "venue": "", "year": 2016 }, { "abstract": "Lead sulfide, a compound consisting of elements with high natural abundance, can be converted into an excellent thermoelectric material. We report extensive doping studies, which show that the power factor maximum for pure n type PbS can be raised substantially to ~12 mW cm( 1) K( 2) at >723 K using 1.0 mol PbCl(2) as the electron donor dopant. We also report that the lattice thermal conductivity of PbS can be greatly reduced by adding selected metal sulfide phases. The thermal conductivity at 723 K can be reduced by ~50% 52% 30% and 42% through introduction of up to 5.0 mol Bi(2)S(3) Sb(2)S(3) SrS, and CaS, respectively. These phases form as nanoscale precipitates in the PbS matrix, as confirmed by transmission electron microscopy (TEM) and the experimental results show that they cause huge phonon scattering. As a consequence of this nanostructuring, ZT values as high as 0.8 and 0.78 at 723 K can be obtained for nominal bulk PbS material. When processed with spark plasma sintering, PbS samples with 1.0 mol Bi(2)S(3) dispersion phase and doped with 1.0 mol PbCl(2) show even lower levels of lattice thermal conductivity and further enhanced ZT values of 1.1 at 923 K. The promising thermoelectric properties promote PbS as a robust alternative to PbTe and other thermoelectric materials.", "author_names": [ "Li-dong Zhao", "Shih Han Lo", "Jiaqing He", "Hao Li", "Kanishka Biswas", "J G Androulakis", "Chun I Wu", "Timothy P Hogan", "Duck Young Chung", "Vinayak P Dravid", "Mercouri G Kanatzidis" ], "corpus_id": 25204592, "doc_id": "25204592", "n_citations": 336, "n_key_citations": 6, "score": 0, "title": "High performance thermoelectrics from earth abundant materials: enhanced figure of merit in PbS by second phase nanostructures.", "venue": "Journal of the American Chemical Society", "year": 2011 }, { "abstract": "High performance GeTe based thermoelectrics have been recently attracting growing research interest. Here, an overview is presented of the structural and electronic band characteristics of GeTe. Intrinsically, compared to low temperature rhombohedral GeTe, the high symmetry and high temperature cubic GeTe has a low energy offset between L and sigma points of the valence band, the reduced direct bandgap and phonon group velocity, and as a result, high thermoelectric performance. Moreover, their thermoelectric performance can be effectively enhanced through either carrier concentration optimization, band structure engineering (bandgap reduction, band degeneracy, and resonant state engineering) or restrained lattice thermal conductivity (phonon velocity reduction or phonon scattering) Consequently, the dimensionless figure of merit, ZT values, of GeTe based thermoelectric materials can be higher than 2. The mechanical and thermal stabilities of GeTe based thermoelectrics are highlighted, and it is found that they are suitable for practical thermoelectric applications except for their high cost. Finally, it is recognized that the performance of GeTe based materials can be further enhanced through synergistic effects. Additionally, proper material selection and module design can further boost the energy conversion efficiency of GeTe based thermoelectrics.", "author_names": [ "Wei-Di Liu", "Deyong Wang", "Qingfeng Liu", "Wei Zhou", "Zongping Shao", "Zhi-Gang Chen" ], "corpus_id": 218812282, "doc_id": "218812282", "n_citations": 41, "n_key_citations": 0, "score": 0, "title": "High Performance GeTe Based Thermoelectrics: from Materials to Devices", "venue": "", "year": 2020 } ]

[ { "abstract": "Based on density functional theory, the electronic structure and magnetic properties of monolayer PtSe2 doped with different atoms were studied. The Pt and Se atoms are replaced by a transition metal atom (Mn) and a non metal atom X (X N, P, As) respectively. The pristine monolayer PtSe2 is a semiconductor with an indirect band gap of 1.352 eV. For one non metal atom doping, the doped system exhibits indirect band gap magnetic semiconducting properties and the magnetic moment is less than 1 mB and mainly comes from the hybridization of Pt 5d and X p orbitals. The N Doped system still retains the magnetic semiconducting properties under strain (from 10% to 13% and the band gap varies from 0.059 eV to 1.308 eV. For two X doped systems, three different configurations are considered. The doped systems retain the indirect band gap semiconducting properties except for the third nearest neighbor N doped system (direct band gap) But, for all N doped and the second nearest neighbor P doped systems, the magnetic moment increases to more than double. Meanwhile, all X doped monolayer PtSe2 systems exhibit p type semiconducting characteristics. For (Mn, X) co doped systems, the magnetic moments are mainly localized in the Mn 3d orbital and there is strong p d hybridization between Mn atoms and X atoms. The (Mn, N/P) co doped system still exhibits magnetic semiconducting properties. These results are important for designing semiconductor devices and electronic spin devices based on monolayer PtSe2.", "author_names": [ "Xu Zhao", "Ranzhuo Huang", "Tianxing Wang", "Xianqi Dai", "Shuyi Wei", "Yaqiang Ma" ], "corpus_id": 211536249, "doc_id": "211536249", "n_citations": 6, "n_key_citations": 0, "score": 2, "title": "Steady semiconducting properties of monolayer PtSe2 with non metal atom and transition metal atom doping.", "venue": "Physical chemistry chemical physics PCCP", "year": 2020 }, { "abstract": "Using first principles calculations, we have studied the energetic feasibility and magnetic properties of transition metal (TM) doped PtSe2 monolayers. Our study shows that TM doped PtSe2 layers with 6.25% doping exhibit versatile spintronic behaviour depending on the nature of the dopant TM atoms. Groups IVB and VIII10 TM doped PtSe2 layers are non magnetic semiconductors, while groups IIIB, VB, VIII8, VIII9, IB TM doped PtSe2 layers are half metals and finally, groups VIB, VIIB and IIB TM doped PtSe2 layers are spin polarized semiconductors. The presence of half metallic and magnetic semiconducting characteristics suggest that TM doped PtSe2 layers can be considered as a new kind of dilute magnetic semiconductor and thus have the promise to be used in spintronics. By studying the magnetic interactions between two TM dopants in PtSe2 monolayers for dopant concentration of 12.5% and dopant distance of 12.85 [Formula: see text] we have found that in particular, Fe and Ru doped PtSe2 systems are ferromagnetic half metal having above room temperature Curie point of 422 and 379.9 K, respectively. By varying the dopant distance and concentration we have shown that the magnetic interaction is strongly dependent on dopant distance and concentration. Interestingly, the Curie temperature of TM doped PtSe2 layers is affected by the correlation effects on the TM d states and also spin orbit coupling. We have also studied the magnetic properties of defect complex composed of one TM dopant and one Pt vacancy (TMPt VPt) which shows novel magnetism.", "author_names": [ "Moumita Kar", "Ritabrata Sarkar", "Sougata Pal", "Pranab Kumar Sarkar" ], "corpus_id": 58630273, "doc_id": "58630273", "n_citations": 26, "n_key_citations": 0, "score": 1, "title": "Engineering the magnetic properties of PtSe2 monolayer through transition metal doping.", "venue": "Journal of physics. Condensed matter an Institute of Physics journal", "year": 2019 }, { "abstract": "Abstract The structure, electronic, and magnetic properties of 5d series transition metal atoms (TMs) (Hf to Hg) substitution doping antimonene are systematically investigated within the framework of the generalized gradient approximation density functional theory (DFT GGA) calculations. Our results indicate that identical magnetic ground states are obtained both GGA and GGA with on site Coulomb repulsion (GGA U) methods, and the magnetic moment mainly arises from the localized 5d electrons of the 5d TMs. By selective doping different 5d TM atom, antimonene can be regulated from a spin non polarized to spin polarized semiconductor and metal. Interestingly, based on GGA U level, we have demonstrated the spin polarized semiconducting properties of Hf, Ta, W, Re, Os substituted antimonene systems, and they can further transform into magnetic half metallic by electronic or hole doping. Besides these, the weak magnetic coupling is found in the two identical TM impurity antimonene systems. The largest perpendicular magnetic anisotropy energy (MAE) manifests in Re@Sb, up to 18.33 meV in our research systems, and its physics origin of the large MAE is explored in detail in this article. These findings provide an efficient method to tune the physics properties of antimonene, supporting the potential application in the field of spintronics.", "author_names": [ "Huiqiang Guo", "Jin Lv", "Hai-Shun Wu" ], "corpus_id": 214159274, "doc_id": "214159274", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "Electronic and magnetic properties of 5d transition metal substitution doping monolayer antimonene: within GGA and GGA U framework", "venue": "", "year": 2020 }, { "abstract": "Graphene like BC3 monolayer as a new semiconducting nanomaterial has many unique properties. First, we investigate the adsorption behaviors of different adatoms (N, Si and P) on pristine and single vacancy of BC3 (pri and SV BC3) using first principles calculations. It was found that the non metal (NM) adatoms have small diffusion barriers and tend to be mobile on the pri BC3 sheet; yet, these NM atom doped BC3 systems (NM BC3) exhibited high stability. Second, the adsorption of O2 molecule on the Si BC3 system was more stable than that on other substrates (N and P BC3) resulting in a change in the electronic structure and magnetic properties of the system. Moreover, the possible CO oxidation reactions on the Si BC3 sheet through the Eley Rideal (ER) mechanism were comparatively investigated. For the initial step, the preadsorbed O2 reacting with CO to form CO3 or OOCO complex had a smaller energy barrier <0.50 eV) than the dissociation reaction of the O2 molecule. The formation of the CO3 complex was quite stable on the Si BC3 sheet; yet, the presence of the CO molecule promoted the decomposition of the CO3 complex and then formed two CO2 molecules through ER reactions. These results contribute toward designing more effective and metal free single atom catalysts and broaden the applications of graphene like materials.", "author_names": [ "Yanan Tang", "Minghui Zhang", "Zigang Shen", "Jincheng Zhou", "Huadou Chai", "Xianqi Dai" ], "corpus_id": 103778841, "doc_id": "103778841", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Non metal atom anchored BC3 sheet: a promising low cost and high activity catalyst for CO oxidation", "venue": "", "year": 2018 }, { "abstract": "Abstract To enrich the electronic and induce useful magnetic properties of the monolayer black phosphorene (BP) we study the structural, electric and magnetic properties of substitutional 4d transition metal (TM) impurities in BP by means of first principles methods. In the 4d single TM atom doped cases, the magnetic moment shows oscillation character with the increasing of the 4d shell valence electrons, which is attributed to the P p and TM d orbital hybridization mechanism. We found no spin polarized state in the Y, Nb, Tc, Rh and Cd doped BP. In other systems, the spin polarized states are found. Importantly, the 4d TMs also enrich the electronic properties of BP, such as half metallic, metallic and semiconducting features. For two same TMs doped BP, the 2Mo doping on the both sides of BP show a half metal character. Only 2Nb doped BP shows diluted magnetic semiconductor (DMS) character. Interestingly, for two different TMs doped BP, the DMS characteristics can be found in the MoY BP, MoNb BP, MoTc BP and MoRh BP cases. It is worth to be expected that doping with different 4d TMs is a promising method to realize the DMS properties of BP.", "author_names": [ "Yusheng Wang", "Nahong Song", "Na Dong", "Yafeng Zheng", "Xiaohui Yang", "Weifen Jiang", "Bin Xu", "Jianjun Wang" ], "corpus_id": 107567677, "doc_id": "107567677", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Electronic, magnetic properties of 4d series transition metal substituted black phosphorene: A first principles study", "venue": "Applied Surface Science", "year": 2019 }, { "abstract": "Abstract Inducing controllable magnetism in two dimensional non magnetic materials is very important for realizing dilute magnetic semiconductor. Using density functional theory, we have systematically investigated the effect of surface adsorption of various 3d transition metal (TM) atoms (Sc Cu) on the electronic and magnetic properties of the monolayer GaS as representative of group IIIA metal monochalcogenide. We find that all adatoms favor the top site on the Ga atom. All the TM atoms, except for the Cr and Mn, can bond strongly to the GaS monolayer with sizable binding energies. Moreover, the TM decorated GaS monolayers exhibit interesting magnetic properties, which arise from the strong spin dependent hybridization of the TM 3d orbitals with S 3 p and Ga 4s orbitals. After examining the magnetic interaction between two same types of TM atoms, we find that most of them exhibit antiferromagnetic coupling, while Fe and Co atoms can form long range ferromagnetism. Furthermore, we find that the electronic properties of metal decorated systems strongly rely on the type of TM adatom and the adsorption concentration. In particular, the spin polarized semiconducting state can be realized in Fe doped system for a large range of doping concentrations. These findings indicate that the TM decorated GaS monolayers have potential device applications in next generation electronics and spintronics.", "author_names": [ "Heng-Fu Lin", "Li-Min Liu", "Jijun Zhao" ], "corpus_id": 125646377, "doc_id": "125646377", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Electronic and magnetic properties of transition metal decorated monolayer GaS", "venue": "", "year": 2018 }, { "abstract": "Based on the first principles calculations, we investigate the structural, electronic, and magnetic properties of defects in monolayer SnS. We study the formation and migration of vacancies at both Sn and S sites. In comparison to the S site vacancy, our calculations show that creating a vacancy at the Sn site requires lesser energy, indicating that the vacancy at the Sn site is more likely to be formed in experiments with energetic particle irradiation. For the Sn rich (S rich) environment, the vacancy at the S site (Sn site) is more likely to be found than the vacancy at the Sn site (S site) Reducing the formation of vacancy clusters, the S vacancy remains at the position where it is created because of the high vacancy migration barrier. Both types of vacancies remain nonmagnetic. To induce magnetism in monolayer SnS, we also study the transition metal (TM Mn, Fe, and Co) doping at the Sn site and find a significant influence on the electronic and magnetic properties of monolayer SnS. The doping of TM changes non magnetic monolayer SnS to magnetic one and keeps it semiconducting. Additionally, long range ferromagnetic behavior is observed for all the doped system. Hence, doping TM atoms in monolayer SnS could be promising to realize a two dimensional diluted magnetic semiconductor. More interestingly, all the doped TM configurations show a high spin state, which can be used in nanoscale spintronic applications such as spin filtering devices.Based on the first principles calculations, we investigate the structural, electronic, and magnetic properties of defects in monolayer SnS. We study the formation and migration of vacancies at both Sn and S sites. In comparison to the S site vacancy, our calculations show that creating a vacancy at the Sn site requires lesser energy, indicating that the vacancy at the Sn site is more likely to be formed in experiments with energetic particle irradiation. For the Sn rich (S rich) environment, the vacancy at the S site (Sn site) is more likely to be found than the vacancy at the Sn site (S site) Reducing the formation of vacancy clusters, the S vacancy remains at the position where it is created because of the high vacancy migration barrier. Both types of vacancies remain nonmagnetic. To induce magnetism in monolayer SnS, we also study the transition metal (TM Mn, Fe, and Co) doping at the Sn site and find a significant influence on the electronic and magnetic properties of monolayer SnS. The doping of", "author_names": [ "Hamid Ullah", "Mohammad Noor-A-Alam", "Hye Jung Kim", "Young-Han Shin" ], "corpus_id": 125470446, "doc_id": "125470446", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "Influences of vacancy and doping on electronic and magnetic properties of monolayer SnS", "venue": "", "year": 2018 }, { "abstract": "In view of important role of inducing the magnetism in semiconducting transition metal dichalcogenides monolayer, the influences of a series of transition metal and alkaline earth dopants, including Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd and In, on the electronic and magnetic properties of semiconducting CrS2 monolayer are systematically investigated using first principles calculations. The calculations show that Nb, Mo, Ru and Rh dopants cannot induce the magnetism in doped CrS2 monolayer, whereas ground states of Ca, Sc, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr, Y, Zr, Pd, Ag, Cd and In doped system are magnetic and the stability of magnetic state of V doped system is small. Furthermore the value and the distribution of the magnetic moment induced by dopant not only relate to the number of valence electrons and the occupancy of the d orbitals of dopant, but also depend on the hybridization between dopant and its neighboring S and Cr atoms. Note that it is found that the substitutional doping at the Cr site of CrS2 monolayer with numerous transition metal and alkaline earth atoms should be possible under the Cr poor growth conditions. Overall, the calculated results show high potential for inducing the magnetism in CrS2 monolayer by doping at the Cr site.", "author_names": [ "Jianming Zhang", "Huiling Zheng", "Ruilin Han", "Xiaobo Du", "Yu Yan" ], "corpus_id": 92758324, "doc_id": "92758324", "n_citations": 21, "n_key_citations": 0, "score": 0, "title": "Tuning magnetic properties of CrS2 monolayer by doping transition metal and alkaline earth atoms", "venue": "", "year": 2015 }, { "abstract": "Abstract The electronic structures and magnetic properties of X doped (X Ni, Pd, Pt) InSe monolayers were investigated using first principles calculations based on the GGA+U method. We show that the chemical doping is easier to take place at Se rich than In rich environment, and that Pt substitution of In is energetically most favorable among the three types of doping, followed by Ni and Pd. We further conduct calculation of ground state and band structures of Ni Pd and Pt doped InSe monolayers and find that the doped systems show diluted magnetic semiconducting nature. The magnetic moments of the X doped systems are dominantly originated from the X dopants, and their extent of spin density expansion to the neighboring atoms is stronger in Pd and Pt doped cases than Ni doped case. Further analysis of the impurity states near the Fermi energy reveals a strong spin polarization feature in the three doped systems. Our results demonstrate that substitutional doping with Ni, Pd and Pt in InSe monolayer represents an effective manner to modulate electronic and magnetic properties of InSe for spintronic applications.", "author_names": [ "Zhi Xie", "Sile Lin", "Zhongchang Wang" ], "corpus_id": 139712067, "doc_id": "139712067", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "Electronic structure and magnetism in transition metal doped InSe monolayer: A GGA U study", "venue": "", "year": 2018 }, { "abstract": "Abstract In this paper, the structural, electric and magnetic properties of transition metal (TM) doped monolayer Tl2S are investigated by means of first principles methods The results show that all the considered TM atoms are strongly bonded to the Tl vacancy site. The magnetic moment, the dilute magnetic semiconductor and metal characteristics are varied depending on the specific TM atoms. The TM doped Tl2S (TM Tl2S) (from Sc to Ni) systems have fractional magnetic moments changing from 0.539 mB to 4.479 mB. However, Cu and Zn Tl2S systems exit the nonmagnetic ground states. The spin polarized metallic states are achieved by Sc, Ti, V, Mn and Fe doping, while spin polarized semiconducting states are realized by Cr, Co and Ni doping. The charge transfer, the total magnetic moment and the band gap obtained with PBE method are less than the values obtained by PBE U, which suggests that the Hubbard U plays an important role in TM Tl2S systems. In the case of two same types of TM atoms doped Tl2S systems, there exist AFM in Sc V Mn Tl2S systems and FM only in Ti Tl2S system. Interestingly, the Cr Fe Co Ni Tl2S systems manifest paramagnetic. These findings may provide a new route for exploring two dimensional diluted magnetic semiconductors experimentally and theoretically.", "author_names": [ "Nahong Song", "Yusheng Wang", "Weiyang Yu", "Liying Zhang", "Yuye Yang", "Yu Jia" ], "corpus_id": 135968755, "doc_id": "135968755", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Electronic, magnetic properties of transition metal doped Tl 2 S: First principles study", "venue": "", "year": 2017 } ]

[ { "abstract": "Photoexcited electron transfer between donor and acceptor molecular semiconductors provides a method of efficient charge generation following photoabsorption, which can be exploited in photovoltaic diodes. But efficient charge separation and transport to collection electrodes is problematic, because the absorbed photons must be close to the donor acceptor heterojunction, while at the same time good connectivity of the donor and acceptor materials to their respective electrodes is required. Mixtures of acceptor and donor semiconducting polymers, (or macromolecules) can provide phase separated structures which go some way to meeting this requirement, providing high photoconductive efficiencies. Here we describe two layer polymer diodes, fabricated by a lamination technique followed by controlled annealing. The resulting structures provide good connectivity to the collection electrodes, and we achieve a short circuit photovoltaic quantum efficiency of up to 29% at optimum wavelength, and an overall power conversion efficiency of 1.9% under a simulated solar spectrum. Given the convenience of polymer processing, these results indicate a promising avenue towards practical applications for such devices.", "author_names": [ "Magnus Granstrom", "Klaus Petritsch", "Ana Claudia Arias", "Andrea Lux", "Mats R Andersson", "Richard H Friend" ], "corpus_id": 4361418, "doc_id": "4361418", "n_citations": 1087, "n_key_citations": 6, "score": 1, "title": "Laminated fabrication of polymeric photovoltaic diodes", "venue": "Nature", "year": 1998 }, { "abstract": "This study presents the slot die coating process of two layers of organic materials for the fabrication of organic light emitting diodes (OLEDs) Poly(3,4 ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) which is commonly used in OLEDs and in organic photovoltaic devices as the hole injection layer (HIL) has been deposited via slot die coating. Uniform films of PEDOT:PSS were obtained after optimizing the slot die processing parameters: substrate temperature, coating speed, and ink flow rate. The film quality was examined using optical microscopy, profilometry, and atomic force microscopy. Further, poly(9,9 dioctylfluorene) (F8) and poly(9,9 dioctylfluorene alt benzothiadiazole) (F8BT) a well know polymer blend F8:F8BT, which is used as an emissive layer in OLEDs, has been slot die coated. The optoelectronic properties of the slot die coated F8:F8BT films were examined by means of photoluminescence (PL) and electroluminescence (EL) studies. The fabricated OLEDs, consisting of slot die coated PEDOT:PSS and F8:F8BT films, were characterized to record the brightness and current efficiency.", "author_names": [ "Amruth C", "Marco Colella", "Jonathan L W Griffin", "James William Kingsley", "Nicholas W Scarratt", "Beata Luszczynska", "Jacek Ulanski" ], "corpus_id": 58539261, "doc_id": "58539261", "n_citations": 14, "n_key_citations": 0, "score": 0, "title": "Slot Die Coating of Double Polymer Layers for the Fabrication of Organic Light Emitting Diodes", "venue": "Micromachines", "year": 2019 }, { "abstract": "Abstract The hierarchical micro /nanotextures adorning the petal surfaces of certain flower species exhibit outstanding sunlight harvesting properties, which can be exploited for photovoltaic (PV) applications via a direct replication approach into polymeric cover layers. This route has been so far hampered by the restricted size of the original bio template and by the limited number of replication cycles when a polymeric mold is used. Here, we therefore introduce an upscaling strategy allowing the fabrication of mechanically stable, temperature resistant and large area nickel mold inserts which can be employed for hot embossing lithography, and ultimately for the mass production of bioreplicated films that improve light management in PV modules. As a proof of concept, we laminate the thus produced textured foils, here corresponding to rose petal replicas, onto glass encapsulated copper indium gallium diselenide (CIGS) solar modules with a surface of 100 cm2. We demonstrate an increase of the power output of 5.4% with respect to a device with an uncoated glass cover layer (measured in outdoor operating conditions) This improvement is notably attributed to the excellent light in coupling properties of the replicated texture at high oblique incidence angles.", "author_names": [ "Benjamin Fritz", "Ruben Hunig", "Markus Guttmann", "Marc Schneider", "K M Samaun Reza", "Oliver Salomon", "Philip L Jackson", "Michael Powalla", "Uli Lemmer", "Guillaume Gomard" ], "corpus_id": 216385587, "doc_id": "216385587", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "Upscaling the fabrication routine of bioreplicated rose petal light harvesting layers for photovoltaic modules", "venue": "", "year": 2020 }, { "abstract": "Organometal halide perovskite light emitting diodes (LEDs) with laminated carbon nanotube (CNT) electrodes are reported. The LEDs have an indium tin oxide (ITO) bottom electrode, a screen printed methylammonium lead tribromide (MAPbBr3)/polymer composite thin film as the emissive layer, and laminated CNT as the top electrode. The devices can be turned on at 2.2 V, reaching a brightness of 4,960 cd m 2 and a current efficiency of 1.54 cd A 1 at 6.9 V. The greatly simplified fabrication process in this work can potentially lead to the scalable manufacturing of large size and low cost LED panels in the future.", "author_names": [ "Xin Shan", "Sri Ganesh R Bade", "Thomas Geske", "Melissa B Davis", "Rachel R Smith", "Zhibin Yu" ], "corpus_id": 104208812, "doc_id": "104208812", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Organometal halide perovskite light emitting diodes with laminated carbon nanotube electrodes", "venue": "Organic Photonics Electronics", "year": 2017 }, { "abstract": "Abstract This work presents post fabrication electric field and heat treatment methods developed for polymer light emitting diodes (PLEDs) which have degraded due to exposure to oxygen and water vapors during low cost fabrication performed in standard room conditions. Investigated PLEDs have structures composed of indium tin oxide (ITO) poly(3,4 ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) poly[2 methoxy 5 (2' ethyl hexyloxy) 1,4 phenylene vinylene] (MEH PPV) and aluminum (Al) Heat treatment restores the light emitting function of dysfunctional PLEDs but also causes a high turn on voltage of 10 V. Electric field treatment utilizing 1 V reduces this high turn on voltage to 3 V. This procedure also improves open circuit voltages from 5 mV to 55 mV, and short circuit currents from 0.5 nA to 5 nA when PLEDs are operated as photovoltaic cells under a light intensity of 500 mW/m2. Repeated I V sweep measurements additionally show improved stability and uniformity. The reasons for these improvements, the usage of an optimal treatment temperature of 130 degC, and the usage of treatment voltages of 0 and 1 V are discussed.", "author_names": [ "A O Sevim", "Senol Mutlu" ], "corpus_id": 59485650, "doc_id": "59485650", "n_citations": 26, "n_key_citations": 0, "score": 0, "title": "Post fabrication electric field and thermal treatment of polymer light emitting diodes and their photovoltaic properties", "venue": "", "year": 2009 }, { "abstract": "Materials with a combination of high electrical conductivity and optical transparency are important components of many electronic and optoelectronic devices such as liquid crystal displays, solar cells, and light emitting diodes. In this study, to fabricate a low resistance and high optical transparent electrode film for organic photovoltaic, the following steps were performed: the design and manufacture of an electroforming stamp mold, the fabrication of thermal roll imprinted (TRI) poly carbonate (PC) patterned films, the manufacture of high conductivity and low resistance Ag paste which was filled into patterned PC film using a doctor blade process and then coated with a thin film layer of conductive polymer by a spin coating process. As a result of these imprinting processes the PC films obtained a line width of 10{pm}0.5{mu}m, a channel length of 500{pm}2{mu}m, and a pattern depth of 7.34{pm}0.5{mu}m. After the Ag paste was used to fill part of the patterned film with conductive polymer coating, the following parameters were obtained: a sheet resistance of 9.65{Omega}/sq, optical transparency values were 83.69 at a wavelength of 550 nm.", "author_names": [ "" ], "corpus_id": 137786898, "doc_id": "137786898", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Fabrication of Transparent Electrode Film for Organic Photovoltaic using Ag grid and Conductive Polymer", "venue": "", "year": 2011 }, { "abstract": "An effective electron injection layer (EIL) is crucial to efficient polymer light emitting diodes (PLEDs) with high work function metal as cathode. This work presents the use of water/alcohol soluble poly(vinyl alcohol) (PVA) especially doped with alkali metal salts, as a highly effective EIL to fabricate efficient multilayer PLEDs, allowing the use of stable aluminum as the cathode. Using neat PVA as EIL, the maximum brightness and maximum current efficiency of the device [ITO/PEDOT:PSS/SY/PVA/Al(90 nm) were significantly enhanced to 5518 cd/m2 and 2.64 cd/A (from 395 cd/m2 and 0.06 cd/A without the EIL) due to promoted electron injection and hole blocking. The device performance is further enhanced by doping the PVA with alkali metal salts (M2CO3 or CH3COOM; M: Na, K, Cs) and the enhancement is increased with increasing dopant concentration. Particularly, the PVA doped with 30 wt% alkali metal carbonates revealed the best performance (20214 25163 cd/m2, 5.83 6.83 cd/A) This has been attributed to improved electron injection from aluminum cathode, which has been confirmed by the corresponding increase in the open circuit voltages (Voc) obtained from photovoltaic measurements. Current results indicate that commercially available PVA are promising electron injection layer for PLEDs when doped with appropriate alkali metal salts.", "author_names": [ "Cheng Liang Wu", "Cheng Yi Lin", "Yun Chen" ], "corpus_id": 102173018, "doc_id": "102173018", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Fabrication of efficient polymer light emitting diodes using water/alcohol soluble poly(vinyl alcohol) doped with alkali metal salts as electron injection layer", "venue": "Journal of Materials Science", "year": 2016 }, { "abstract": "Abstract Non traditional photovoltaic (PV) modules, such as solar shingles, facades and skins, are expected to increase in market share as the solar industry matures and moves to fill building integrated photovoltaics niches. The advent of building integration and the application of photovoltaics to multiple surfaces come with fabrication challenges and inherent geometrical, optical and thermal constraints. In this paper, we investigate the curved lamination process and the integration of a dichroic polymeric film within the laminate for the particular case of a large scale optical collector called a \"PVMirror\" PVMirror is a concentrating solar power (CSP)/PV hybrid design that combines the high efficiency of PV and storage capability of CSP using a dichroic film. The film does not degrade upon lamination and exhibits good adhesion to encapsulants. Multiple lamination approaches, such as tuning the thickness of the encapsulant, are shown to significantly reduce the impact of the lamination process on the shape error of PVMirror modules, which could also be applied to the fabrication of other non traditional PV modules.", "author_names": [ "Xiaodong Meng", "Kathryn C Fisher", "Lennon O Reinhart", "Wyatt S Taylor", "Michael E Stuckelberger", "Zachary C Holman", "Mariana I Bertoni" ], "corpus_id": 201221280, "doc_id": "201221280", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Optical characterization of curved silicon PV modules with dichroic polymeric films", "venue": "Solar Energy Materials and Solar Cells", "year": 2019 }, { "abstract": "Recent work on solar cells based on interpenetrating polymer networks and solid state dye sensitized devices shows that efficient solar energy conversion is possible using organic materials. Further, it has been demonstrated that the performance of photovoltaic devices based on small molecules can be effectively enhanced by doping the organic material with electron accepting molecules. But as inorganic solar cells show much higher efficiencies, well above 15 per cent, the practical utility of organic based cells will require their fabrication by lower cost techniques, ideally on flexible substrates. Here we demonstrate efficiency enhancement by molecular doping in Schottky type photovoltaic diodes based on pentacene an organic semiconductor that has received much attention as a promising material for organic thin film transistors, but relatively little attention for use in photovoltaic devices. The incorporation of the dopant improves the internal quantum efficiency by more than five orders of magnitude and yields an external energy conversion efficiency as high as 2.4 per cent for a standard solar spectrum. Thin film devices based on doped pentacene therefore appear promising for the production of efficient 'plastic' solar cells.", "author_names": [ "Jan Hendrik Schon", "Christian Kloc", "Ernst Bucher", "Bertram J Batlogg" ], "corpus_id": 4391485, "doc_id": "4391485", "n_citations": 140, "n_key_citations": 2, "score": 0, "title": "Efficient organic photovoltaic diodes based on doped pentacene", "venue": "Nature", "year": 2000 }, { "abstract": "Poly(p phenylene vinylene) (PPV) is a family of conjugated polymers that have been used in a variety of fields, including light emitting diodes, light emitting transistors, photovoltaic cells, and sensors. PPV is generally synthesized by a Wittig or a Knoevenagel condensation reaction. Owing to its poor solubility, it has been difficult to utilize PPV in solutionbased manufacturing processes. To overcome this issue, alkoxysubstituted PPVs, such as poly[2 methoxy 5 (2 ethylhexyloxy) 1,4 phenylenevinylene] (MEH PPV) (Scheme I) have been developed. The long alkyl substituents enhance the solubility in common organic solvents. In addition, there have been numerous attempts to tune the emission wavelength of PPV for display applications. Depending on the substituents and steric hindrance, the fluorescence of PPV can be tuned from blue to red. Many efforts have been devoted to fabricate patterned PPV images on solid substrates. For instance, Dirk and coworkers reported the patterning of PPV using a photolabile xanthate group. PPV patterns were produced by elimination of xanthate groups upon exposure to UV light. In addition, patterns can be fabricated by employing photolithography, micromoldingin capillaries (MIMIC) and array spotting techniques. Among the various patterning methods, the photolithographic approach has been considered as the most reliable due to its high scalability and resolution. Conventional photolithographic methods generally utilize precursor PPVs that are converted to PPVs by UV irradiation. Polydiacetylenes (PDAs) discovered by Wegner in 1969, are optically and structurally unique conjugated polymers. When 254 nm UV light is irradiated on self assembled diacetylene (DA) monomers, 1,4 addition polymerization occurs to form a colored (typically blue) PDA. Polydiacetylene (PDA) shows a color transition (typically blue to red) and exhibits self fluorescence when exposed to external stimuli. In addition, the solubility of PDA in common organic solvents is drastically decreased after polymerization. We hypothesized that, if a thin film of PPV containing DA moieties (PPV DA) is UV irradiated with a photomask, photoinduced PDA formation should occur in the UV exposed area (Figure 1) Subsequent development of the film in an organic solvent should remove any organic solvent soluble (UV unirradiated) part, leaving patterned PPV images behind.", "author_names": [ "Sumin Park", "Seongho Jeon", "Tae Geun Kim", "Jong-Man Kim" ], "corpus_id": 99465957, "doc_id": "99465957", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A side chain crosslinking approach for the fabrication of conjugated polymer patterns", "venue": "Macromolecular Research", "year": 2016 } ]

[ { "abstract": "In semiconductor device manufacturing, optical overlay metrology measures pattern placement between two layers in a chip with sub nm precision. Continuous improvements in overlay metrology are needed to keep up with shrinking device dimensions in modern chips. We present first overlay metrology results using a novel off axis dark field digital holographic microscopy concept that acquires multiple holograms in parallel by angular multiplexing. We show that this concept reduces the impact of source intensity fluctuations on the noise in the measured overlay. With our setup we achieved an overlay reproducibility of 0.13 nm and measurements on overlay targets with known programmed overlay values showed good linearity of R2= 0.9993. Our data show potential for significant improvement and that digital holographic microscopy is a promising technique for future overlay metrology tools.", "author_names": [ "Christos Messinis", "Theodorus Thomas Marinus van Schaijk", "Nitesh Pandey", "Vasco T Tenner", "Stefan Witte", "Johannes F de Boer", "Arie J den Boef" ], "corpus_id": 228885458, "doc_id": "228885458", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Diffraction based overlay metrology using angular multiplexed acquisition of dark field digital holograms.", "venue": "Optics express", "year": 2020 }, { "abstract": "Metrology requirements at advanced nodes are not only tightening on specifications but also broadening in terms of flexibility needed to cover variety of product stacks. Metrology targets need to be process compatible and at the same time these targets should also be readable by the metrology system. In some cases, process conditions require a target pitch that is large compared to the wavelength used by the metrology system. Examples of these situations include for instance topography transfer or stacks with thick resist (for e.g. 3D NAND) Traditionally overlay is extracted from the asymmetry in the positive and negative first diffraction order generated from mDBO targets. However, when the pitch is large, the targets generate multiple higher diffraction orders. Current state of the art diffraction based overlay systems do not take into account the effect of these higher diffraction orders and typically only select the first diffraction order. This is done by reducing the pitch of the target, tuning the wavelength or by changing the angle of incidence of the illumination light. To address wavelength over pitch flexibility an advanced algorithm was introduced on a new metrology system in the fab, providing full flexibility in the selection of measurement wavelength and pitch. To obey the specifications on accuracy and throughput, we will present a new metrology system that is, compared to its predecessor, about 2x faster and able to measure more accurately because of the ability to measure multiple wavelengths within the same time frame.", "author_names": [ "Simon Gijsbert Josephus Mathijssen", "Herman Heijmerikx", "Farzad Farhadzadeh", "M J Noot", "Lineke van der Sneppen", "Longfei Shen", "Fei Jia", "Jolly Xu", "Huajun Qin", "Arie J den Boef", "Elliott Mc Namara", "Kaustuve Bhattacharyya", "Chao Fang", "Yaobin Feng" ], "corpus_id": 215790093, "doc_id": "215790093", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Enhancing the applications space of diffraction based overlay metrology by increasing throughput and target pitch flexibility", "venue": "Advanced Lithography", "year": 2020 }, { "abstract": "Overlay target design is an important issue in overlay metrology, whose aim is to probe the optimal overlay target to achieve good performance on measurement precision and accuracy even in the presence of process variation. In this paper, the target design problem is first formulated as a multiobjective optimization problem and then solved by the multiobjective genetic algorithm. The feasibility of the proposed method is verified based on simulations carried out on two overlay targets. The results reveal that measurements with high precision, accuracy, and process robustness could be achieved on the targets designed by the proposed method.", "author_names": [ "Yating Shi", "Kuangyi Li", "Xiuguo Chen", "Peng Wang", "Honggang Gu", "Hao Jiang", "Chuanwei Zhang", "Shiyuan Liu" ], "corpus_id": 214061047, "doc_id": "214061047", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Multiobjective optimization for target design in diffraction based overlay metrology.", "venue": "Applied optics", "year": 2020 }, { "abstract": "In semiconductor device manufacturing, optical overlay metrology measures pattern placement between two layers in a chip with sub nm precision. Continuous improvements in overlay metrology are needed to keep up with shrinking device dimensions in modern chips. We present first overlay metrology results using a novel off axis dark field digital holographic microscopy concept that acquires multiple holograms in parallel by angular multiplexing. We show that this concept reduces the impact of source intensity fluctuations on the noise in the measured overlay. With our setup we achieved an overlay reproducibility of 0.13 nm and measurements on overlay targets with known programmed overlay values showed good linearity of R2= 0.9993. Our data show potential for significant improvement and that digital holographic microscopy is a promising technique for future overlay metrology tools. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement", "author_names": [ "", "M T", "T T", "R W Og Den" ], "corpus_id": 229378208, "doc_id": "229378208", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Diffraction based overlay metrology using angular multiplexed acquisition of dark field digital holograms", "venue": "", "year": 2020 }, { "abstract": "Scatterometry is an optical metrology technique, in which light scattered from a specifically designed grating stack (overlay target) is measured in the far field. Using 1D periodic overlay target designs the technique has been shown to have nanometer scale sensitivity to spatial misalignments of subsequent patterned layers, which are also known as overlay errors. However, while scatterometry is highly sensitive to overlay errors, multiple sources of systematic errors hinder its absolute accuracy. Here, we investigate how an extended version of scatterometry called Fourier scatterometry in combination with more complex overlay target designs can help addressing those challenges. To this end, we developed a statistical method, which can determine the influence of 2D overlay targets on the overlay measurement uncertainty. We study periodic and deterministic aperiodic designs as well as designs that emerged from simulated annealing optimizations. Our results suggest that current overlay target designs could be augmented by more complex 2D designs to fulfill specific purposes, such as fabrication robustness and high sensitivity over a large overlay range.", "author_names": [ "Ruslan Rohrich", "Giorgio Oliveri", "Stefanos Kovaios", "Vasco T Tenner", "Arie J den Boef", "Johannes T B Overvelde", "A Femius Koenderink" ], "corpus_id": 221737443, "doc_id": "221737443", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Uncertainty Estimation and Design Optimization of 2D Diffraction Based Overlay Metrology Targets", "venue": "", "year": 2020 }, { "abstract": "The current state of the art ADI overlay metrology relies on multi wavelength uDBO techniques. Combining the wavelengths results in better robustness against process effects like process induced grating asymmetries. Overlay information is extracted in the image plane by determining the intensity asymmetry in the 1st order diffraction signals of two grating pairs with an intentional shift (bias) In this paper we discuss a next evolution in DBO targets where a target is created with multiple biases. These so called cDBO (continuous bias DBO) targets have a slightly different pitch between top and bottom grating, which has the effect of having a different bias values along the grating length and are complimentary to the uDBO technology. Where for the uDBO target, the diffraction results in a uniform Intensity pattern that carries the Overlay signal, for cDBO, an oscillating intensity pattern occurs, and the Overlay information is now captured in the phase of that pattern. Phase based Overlay has an improved, intrinsic robustness over intensity based overlay and can reduce the need for multi wavelength techniques in several cases. Results on memory technology wafers confirm that the swing curve (through wavelength) behavior is indeed more stable for phase based DBO target and that for accurate Overlay, this target can be qualified with a single wavelength recipe (compared to the uDBO dual wavelength recipe) In this paper, both initial results on a Micron feasibility wafer will be shown as well as demonstrated capability in a production environment.", "author_names": [ "Masazumi Matsunobu", "Toshiharu Nishiyama", "Michio Inoue", "Richard T Housley", "Cornel Bozdog", "Justin Frederick L Lim", "Brian Watson", "Jason Reece", "Steve McCandless", "Olger Victor Zwier", "Maurits van der Schaar", "Murat Bozkurt", "Masudur al Arif", "Elliott McNamara", "Pieter Kapel", "Alan Khan", "S Strom", "Paul Jonathan Turner", "P A Olson", "Ewoud van West" ], "corpus_id": 233933714, "doc_id": "233933714", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Novel diffraction based overlay metrology utilizing phase based overlay for improved robustness", "venue": "Advanced Lithography", "year": 2021 }, { "abstract": "As 3D NAND devices increase memory density by adding layers, scaling and increasing bits per cell, new overlay (OVL) metrology challenges arise. On product overlay (OPO) may decrease for critical thick layers such as thick deck to deck alignment, whereas high aspect ratio (Z axis) structures introduce stress, tilt and deformation that require accurate and robust OVL measurements. Advanced imaging metrology (AIM(r) targets, that consist of two side byside periodic gratings in the previous and current layers, are typically used to measure OVL with Imaging Based Overlay (IBO) metrology systems. In this paper, we present a new approach that utilizes the Talbot effect in AIM to produce multiple contrast planes along the Z axis, which enables a common focus position for both layers at a similar focus plane, resulting in improved measurement robustness. We will present Talbot effect theory, target design steps by metrology target design (MTD) simulator, actual measurement results on an advanced 3D NAND device and conclusions for such targets.", "author_names": [ "Brian Watson", "Shlomit Katz", "Richard T Housley", "Kar Wui Thong", "Nikhil Aditya Kumar Roy", "Yoav Grauer", "Diana Shapirov", "Raviv Yohanan", "Greg Gray", "Yonglei Li", "Daniel Chalom" ], "corpus_id": 233934050, "doc_id": "233934050", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Robustness improvement in imaging based overlay metrology for high topography layers by Talbot targets", "venue": "Advanced Lithography", "year": 2021 }, { "abstract": "On product overlay (OPO) challenges continue to be yield limiters for most advanced technology nodes, requiring new and innovative metrology solutions. In this paper we will cover an approach to boost accuracy and robustness to process variation in imaging based overlay (IBO) metrology by leveraging optimized measurement conditions per alignment layer. Results apply to both DUV and EUV lithography for advanced Logic, DRAM, 3D NAND and emerging memory devices. Such an approach fuses multi signal information including Color Per Layer (CPL) and focus per layer. This approach with supporting algorithms strives to identify and address sources of measurement inaccuracy to enable tight OPO, improve accuracy stability and reduce overlay (OVL) residual error within the wafer and across lots. In this paper, we will present a theoretical overview, supporting simulations and measured data for multiple technology segments. Lastly, a discussion about next steps and future development will take place.", "author_names": [ "Shlomit Katz", "Yoav Grauer", "Raviv Yohanan", "Xiaolei Liu", "Daria Negri", "Anna Golotsvan" ], "corpus_id": 233951380, "doc_id": "233951380", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Accuracy enhancement in imaging based overlay metrology by optimizing measurement conditions per layer", "venue": "Advanced Lithography", "year": 2021 }, { "abstract": "Digital holographic microscopy allows access to the complex electric field, enabling computational propagation of light. This enables computational corrections for lens aberrations, which remove the requirement for antireflective coatings on the lens and enable imaging over a wide spectral range. This makes digital holographic microscopy an interesting candidate for overlay metrology on semiconductor wafers. We show that a single holographic image contains all data that is required for computing the overlay, by using a source with a limited coherence length and incoherently adding multiple measurements on a camera. As an additional benefit we show that such parallel acquisition improves the reproducibility of the experiment by eliminating noise sources that are common to the two measurements that typically constitute a single overlay measurement.", "author_names": [ "Theodorus Thomas Marinus van Schaijk", "Christos Messinis", "Nitesh Pandey", "Vasco T Tenner", "Armand Koolen", "S Witte", "Johannes F de Boer", "Arie J den Boef" ], "corpus_id": 235716754, "doc_id": "235716754", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Fast and robust diffraction based overlay metrology using dark field digital holographic microscopy", "venue": "Optical Metrology", "year": 2021 }, { "abstract": "Optical overlay metrology has been adopted for years as baseline for overlay control in semiconductor manufacturing. More stringent overlay budget for securing good product yield has been required as device dimension shrinkage. For effective and tight overlay control, the traditional optical overlay metrology has faced two primary challenges of increasing the measurement accuracy and minimizing the measurement variance between overlay mark in scribe lane and in die device pattern. Overlay mark asymmetry is one of the general factors to induce optical overlay metrology error. While 3D NAND deep etch processes would induce within wafer mark asymmetry which worsens measurement robustness of optical overlay metrology. Accurately determining on product overlay (OPO) errors at both after develop inspection (ADI) and after etch inspection (AEI) is also desirable in 3D NAND process for applying non zero offset (NZO) at photo exposure. To address the measurement robustness of optical overlay metrology in 3D NAND process, also for accurately bridging the scribe lane based optical overlay metrology to OPO metrology, a complementary overlay metrology by high voltage scanning electron microscope (HV SEM) was adopted as the reference metrology for optimizing the optical measurement condition on scribe lane targets. In this paper, the measurement accuracy of imaging based overlay (IBO) target under various optical conditions was calibrated by HV SEM. HV SEM can measure both the scribe lane and in device targets via capturing buried structures, and it was employed to bridge the measurement results from IBO and in device target. Then the optimal optical metrology can be decided for both ADI and AEI to facilitate effective advance process control (APC) and NZO purpose.", "author_names": [ "Yu-Lin Liu", "Li-Ting Chang", "Chi-Hao Huang", "Mars Yang", "Elvis Yang", "T H Yang", "K C Chen" ], "corpus_id": 233899674, "doc_id": "233899674", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Imaging based overlay metrology optimized by HV SEM in 3D NAND process", "venue": "Advanced Lithography", "year": 2021 } ]

[ { "abstract": "Abstract Quantum dots (QDs) with several unique optical and chemical features, are becoming desirable fluorescent tags for the biological applications that require long term and highly sensitive imaging. Besides, the conjugation of various functional biomolecules to QDs has enabled wide applications of QDs in biological imaging. This review focuses on the following four types of QDs: semiconductor quantum dots (semiconductor QDs) carbon nanodots (CDs) silicon quantum dots (SiQDs) and polymer dots (Pdots) and summarizes the recent advancements of using these QDs in imaging microorganisms including viruses, bacteria, and fungi. We hope that this review will promote the development of new fluorescent QDs for microbial imaging and extend the applications of QD based imaging techniques in cell biology and beyond.", "author_names": [ "Ge Gao", "Yao-Wen Jiang", "Wei Sun", "Fu-Gen Wu" ], "corpus_id": 105776084, "doc_id": "105776084", "n_citations": 35, "n_key_citations": 0, "score": 1, "title": "Fluorescent quantum dots for microbial imaging", "venue": "", "year": 2018 }, { "abstract": "Research on fluorescent semiconductor nanocrystals (also known as quantum dots or qdots) has evolved over the past two decades from electronic materials science to biological applications. We review current approaches to the synthesis, solubilization, and functionalization of qdots and their applications to cell and animal biology. Recent examples of their experimental use include the observation of diffusion of individual glycine receptors in living neurons and the identification of lymph nodes in live animals by near infrared emission during surgery. The new generations of qdots have far reaching potential for the study of intracellular processes at the single molecule level, high resolution cellular imaging, long term in vivo observation of cell trafficking, tumor targeting, and diagnostics.", "author_names": [ "Xavier Michalet", "Fabien Pinaud", "Laurent A Bentolila", "James M Tsay", "Soren Doose", "Jingyi Jessica Li", "Gobalakrishnan Sundaresan", "Anna M Wu", "Sanjiv Sam Gambhir", "Shimon Weiss" ], "corpus_id": 17004377, "doc_id": "17004377", "n_citations": 6738, "n_key_citations": 67, "score": 0, "title": "Quantum Dots for Live Cells, in Vivo Imaging, and Diagnostics", "venue": "Science", "year": 2005 }, { "abstract": "Fluorescent semiconductor nanocrystals (quantum dots) have the potential to revolutionize biological imaging, but their use has been limited by difficulties in obtaining nanocrystals that are biocompatible. To address this problem, we encapsulated individual nanocrystals in phospholipid block copolymer micelles and demonstrated both in vitro and in vivo imaging. When conjugated to DNA, the nanocrystal micelles acted as in vitro fluorescent probes to hybridize to specific complementary sequences. Moreover, when injected into Xenopus embryos, the nanocrystal micelles were stable, nontoxic <5 x 109 nanocrystals per cell) cell autonomous, and slow to photobleach. Nanocrystal fluorescence could be followed to the tadpole stage, allowing lineage tracing experiments in embryogenesis.", "author_names": [ "Benoit Dubertret", "Paris A Skourides", "David J Norris", "Vincent Noireaux", "Ali H Brivanlou", "Albert Libchaber" ], "corpus_id": 4089168, "doc_id": "4089168", "n_citations": 2639, "n_key_citations": 48, "score": 0, "title": "In Vivo Imaging of Quantum Dots Encapsulated in Phospholipid Micelles", "venue": "Science", "year": 2002 }, { "abstract": "Multicolor optical coding for biological assays has been achieved by embedding different sized quantum dots (zinc sulfide capped cadmium selenide nanocrystals) into polymeric microbeads at precisely controlled ratios. Their novel optical properties (e.g. size tunable emission and simultaneous excitation) render these highly luminescent quantum dots (QDs) ideal fluorophores for wavelength and intensity multiplexing. The use of 10 intensity levels and 6 colors could theoretically code one million nucleic acid or protein sequences. Imaging and spectroscopic measurements indicate that the QD tagged beads are highly uniform and reproducible, yielding bead identification accuracies as high as 99.99% under favorable conditions. DNA hybridization studies demonstrate that the coding and target signals can be simultaneously read at the single bead level. This spectral coding technology is expected to open new opportunities in gene expression studies, high throughput screening, and medical diagnostics.", "author_names": [ "Mingyong Han", "Xiaohu Gao", "Jack Z Su", "Shuming Nie" ], "corpus_id": 3118240, "doc_id": "3118240", "n_citations": 2224, "n_key_citations": 29, "score": 0, "title": "Quantum dot tagged microbeads for multiplexed optical coding of biomolecules", "venue": "Nature Biotechnology", "year": 2001 }, { "abstract": "Quantum dots having four different surface coatings were tested for use in in vivo imaging. Localization was successfully monitored by fluorescence imaging of living animals, by necropsy, by frozen tissue sections for optical microscopy, and by electron microscopy, on scales ranging from centimeters to nanometers, using only quantum dots for detection. Circulating half lives were found to be less than 12 min for amphiphilic poly(acrylic acid) short chain (750 Da) methoxy PEG or long chain (3400 Da) carboxy PEG quantum dots, but approximately 70 min for long chain (5000 Da) methoxy PEG quantum dots. Surface coatings also determined the in vivo localization of the quantum dots. Long term experiments demonstrated that these quantum dots remain fluorescent after at least four months in vivo.", "author_names": [ "Byron T Ballou", "B Christoffer Lagerholm", "Lauren A Ernst", "Marcel P Bruchez", "Alan S Waggoner" ], "corpus_id": 29299927, "doc_id": "29299927", "n_citations": 1072, "n_key_citations": 34, "score": 0, "title": "Noninvasive imaging of quantum dots in mice.", "venue": "Bioconjugate chemistry", "year": 2004 }, { "abstract": "Semiconductor quantum dots (QDs) are among the most promising emerging fluorescent labels for cellular imaging. However, it is unclear whether QDs, which are nanoparticles rather than small molecules, can specifically and effectively label molecular targets at a subcellular level. Here we have used QDs linked to immunoglobulin G (IgG) and streptavidin to label the breast cancer marker Her2 on the surface of fixed and live cancer cells, to stain actin and microtubule fibers in the cytoplasm, and to detect nuclear antigens inside the nucleus. All labeling signals are specific for the intended targets and are brighter and considerably more photostable than comparable organic dyes. Using QDs with different emission spectra conjugated to IgG and streptavidin, we simultaneously detected two cellular targets with one excitation wavelength. The results indicate that QD based probes can be very effective in cellular imaging and offer substantial advantages over organic dyes in multiplex target detection.", "author_names": [ "Xingyong Wu", "Hongjian Liu", "Jianquan Liu", "Kari N Haley", "Joseph A Treadway", "J Peter Larson", "Nianfeng Ge", "Franklin V Peale", "Marcel P Bruchez" ], "corpus_id": 10269136, "doc_id": "10269136", "n_citations": 2244, "n_key_citations": 45, "score": 0, "title": "Immunofluorescent labeling of cancer marker Her2 and other cellular targets with semiconductor quantum dots", "venue": "Nature Biotechnology", "year": 2003 }, { "abstract": "Robust and bright light emitters, semiconductor nanocrystals [quantum dots (QDs) have been adopted as a new class of fluorescent labels. Six years after the first experiments of their uses in biological applications, there have been dramatic improvements in understanding surface chemistry, biocompatibility, and targeting specificity. Many studies have shown the great potential of using quantum dots as new probes in vitro and in vivo. This review summarizes the recent advances of quantum dot usage at the cellular level, including immunolabeling, cell tracking, in situ hybridization, FRET, in vivo imaging, and other related technologies. Limitations and potential future uses of quantum dot probes are also discussed.", "author_names": [ "A Paul Alivisatos", "Weiwei Gu", "Carolyn A Larabell" ], "corpus_id": 29090697, "doc_id": "29090697", "n_citations": 1195, "n_key_citations": 21, "score": 0, "title": "Quantum dots as cellular probes.", "venue": "Annual review of biomedical engineering", "year": 2005 }, { "abstract": "Fluorescent calcium sensors are widely used to image neural activity. Using structure based mutagenesis and neuron based screening, we developed a family of ultrasensitive protein calcium sensors (GCaMP6) that outperformed other sensors in cultured neurons and in zebrafish, flies and mice in vivo. In layer 2/3 pyramidal neurons of the mouse visual cortex, GCaMP6 reliably detected single action potentials in neuronal somata and orientation tuned synaptic calcium transients in individual dendritic spines. The orientation tuning of structurally persistent spines was largely stable over timescales of weeks. Orientation tuning averaged across spine populations predicted the tuning of their parent cell. Although the somata of GABAergic neurons showed little orientation tuning, their dendrites included highly tuned dendritic segments (5 40 um long) GCaMP6 sensors thus provide new windows into the organization and dynamics of neural circuits over multiple spatial and temporal scales.", "author_names": [ "Tsai-Wen Chen", "Trevor J Wardill", "Yi Sun", "Stefan R Pulver", "Sabine L Renninger", "Amy Baohan", "Eric R Schreiter", "Rex A Kerr", "Michael B Orger", "Vivek Jayaraman", "Loren L Looger", "Karel Svoboda", "Douglas S Kim" ], "corpus_id": 4405005, "doc_id": "4405005", "n_citations": 4063, "n_key_citations": 556, "score": 0, "title": "Ultra sensitive fluorescent proteins for imaging neuronal activity", "venue": "Nature", "year": 2013 }, { "abstract": "Advances in molecular biology, organic chemistry, and materials science have recently created several new classes of fluorescent probes for imaging in cell biology. Here we review the characteristic benefits and limitations of fluorescent probes to study proteins. The focus is on protein detection in live versus fixed cells: determination of protein expression, localization, activity state, and the possibility for combination of fluorescent light microscopy with electron microscopy. Small organic fluorescent dyes, nanocrystals \"quantum dots\" autofluorescent proteins, small genetic encoded tags that can be complexed with fluorochromes, and combinations of these probes are highlighted.", "author_names": [ "Ben N G Giepmans", "Stephen R Adams", "Mark H Ellisman", "Roger Tsien" ], "corpus_id": 1288600, "doc_id": "1288600", "n_citations": 2455, "n_key_citations": 47, "score": 0, "title": "The Fluorescent Toolbox for Assessing Protein Location and Function", "venue": "Science", "year": 2006 }, { "abstract": "In 1873, Ernst Abbe discovered that features closer than ~200 nm cannot be resolved by lens based light microscopy. In recent years, however, several new far field super resolution imaging techniques have broken this diffraction limit, producing, for example, video rate movies of synaptic vesicles in living neurons with 62 nm spatial resolution. Current research is focused on further improving spatial resolution in an effort to reach the goal of video rate imaging of live cells with molecular (1 5 nm) resolution. Here, we describe the contributions of fluorescent probes to far field super resolution imaging, focusing on fluorescent proteins and organic small molecule fluorophores. We describe the features of existing super resolution fluorophores and highlight areas of importance for future research and development.", "author_names": [ "Marta Fernandez-Suarez", "Alice Y Ting" ], "corpus_id": 2752640, "doc_id": "2752640", "n_citations": 1092, "n_key_citations": 25, "score": 0, "title": "Fluorescent probes for super resolution imaging in living cells", "venue": "Nature Reviews Molecular Cell Biology", "year": 2008 } ]

[ { "abstract": "Manipulating a defect in diamond Like magnetic storage in today's classical computers, tiny \"magnets\" associated with electronic and nuclear states spins are promising qubits (quantum bits) for the future. Electronic spins in special defects in diamond called nitrogen vacancy (NV) centers are one example. Whereas most applications focus on the least energetic (ground) state of an NV center, Bassett et al. explored the properties of the higher energy (excited) state (see the Perspective by Childress) They used light pulses to bring the system into the excited state and to vary the time it stayed there. In this way, they could both deduce the electronic structure of the excited state and manipulate the ground state spin. Similar methods may be applicable to other quantum information systems. Science, this issue p. 1333; see also p. 1247 The electronic spin in a nitrogen vacancy center in diamond is manipulated with optical pulses alone. [Also see Perspective by Childress] Atom scale defects in semiconductors are promising building blocks for quantum devices, but our understanding of their material dependent electronic structure, optical interactions, and dissipation mechanisms is lacking. Using picosecond resonant pulses of light, we study the coherent orbital and spin dynamics of a single nitrogen vacancy center in diamond over time scales spanning six orders of magnitude. We develop a time domain quantum tomography technique to precisely map the defect's excited state Hamiltonian and exploit the excited state dynamics to control its ground state spin with optical pulses alone. These techniques generalize to other optically addressable nanoscale spin systems and serve as powerful tools to characterize and control spin qubits for future applications in quantum technology.", "author_names": [ "Lee C Bassett", "F Joseph Heremans", "David J Christle", "Christopher G Yale", "Guido Burkard", "Bob B Buckley", "David D Awschalom" ], "corpus_id": 206558512, "doc_id": "206558512", "n_citations": 58, "n_key_citations": 1, "score": 1, "title": "Ultrafast optical control of orbital and spin dynamics in a solid state defect", "venue": "Science", "year": 2014 }, { "abstract": "Optically addressable spin defects in solid state materials have shown great potential for applications ranging from metrology to quantum information processing. Many of these experiments require a detailed understanding of the full Hamiltonian dynamics in order to develop precise quantum control. Here we use picosecond resonant optical pulses to investigate the coherent orbital and spin dynamics of the nitrogen vacancy (NV) center in diamond, over timescales spanning six orders of magnitude. We implement an ultrafast optical pump probe technique to study the NV center's orbital doublet, spin triplet excited state at cryogenic temperatures (T 20 K) where the excited state becomes stable and optically coherent with the ground state. This technique, coupled with optical polarization selection rules, allows us to probe the coherent orbital dynamics of the NV center's excited state [1] These experiments reveal dynamics on femtosecond to nanosecond timescales due to the interplay between the ground and excited state orbital levels. This all optical technique also provides a method to dynamically control the spin state of the NV center by harnessing the excited state structure. Through studying the spin dynamics of the NV center with coherent pulses of light, we are able to rotate the spin state on sub nanosecond timescales. Furthermore, by tuning the excited state spin Hamiltonian with an external magnetic eld, we demonstrate arbitrary axis spin rotations through controlled unitary evolution of the spin state. Extending this to the full excited state manifold, we develop a time domain quantum tomography technique to precisely map the NV center's excited state Hamiltonian. These techniques generalize to other systems and can be a powerful tool in characterizing and controlling qubits in other optically addressable spin systems.", "author_names": [ "F Joseph Heremans" ], "corpus_id": 124623275, "doc_id": "124623275", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Quantum control of orbital and spin dynamics in diamond using ultrafast optical pulses", "venue": "", "year": 2015 }, { "abstract": "Scalable quantum networking requires quantum systems with quantum processing capabilities. Solid state spin systems with reliable spin optical interfaces are a leading hardware in this regard. However, available systems suffer from large electron phonon interaction or fast spin dephasing. Here, we demonstrate that the negatively charged silicon vacancy centre in silicon carbide is immune to both drawbacks. Thanks to its 4A2 symmetry in ground and excited states, optical resonances are stable with near Fourier transform limited linewidths, allowing exploitation of the spin selectivity of the optical transitions. In combination with millisecond long spin coherence times originating from the high purity crystal, we demonstrate high fidelity optical initialization and coherent spin control, which we exploit to show coherent coupling to single nuclear spins with ~1 kHz resolution. The summary of our findings makes this defect a prime candidate for realising memory assisted quantum network applications using semiconductor based spin to photon interfaces and coherently coupled nuclear spins.Point defects in solids have potential applications in quantum technologies, but the mechanisms underlying different defects' performance are not fully established. Nagy et al. show how the wavefunction symmetry of silicon vacancies in SiC leads to promising optical and spin coherence properties.", "author_names": [ "Roland Nagy", "Matthias Niethammer", "Matthias Widmann", "Yu-Chen Chen", "Peter Udvarhelyi", "Cristian Bonato", "Jawad Ul Hassan", "Robin Karhu", "Ivan G Ivanov", "Nguyen Tien Son", "Jer'onimo R Maze", "Takeshi Ohshima", "Oney O Soykal", "Adam Gali", "Sang-Yun Lee", "Florian Kaiser", "Jorg Wrachtrup" ], "corpus_id": 119397688, "doc_id": "119397688", "n_citations": 91, "n_key_citations": 3, "score": 0, "title": "High fidelity spin and optical control of single silicon vacancy centres in silicon carbide", "venue": "Nature Communications", "year": 2019 }, { "abstract": "Optically interfaced spins in the solid state are a promising platform for quantum technologies. A crucial component of these systems is high fidelity, projective measurement of the spin state. In previous work with laser cooled atoms and ions, and solid state defects, this has been accomplished using fluorescence on an optical cycling transition; however, cycling transitions are not ubiquitous. In this work, we demonstrate that modifying the electromagnetic environment using an optical cavity can induce a cycling transition in a solid state atomic defect. By coupling a single Erbium ion defect to a telecom wavelength silicon nanophotonic device, we enhance the cyclicity of its optical transition by a factor of more than 100, which enables single shot quantum nondemolition readout of the ion's spin with 94.6% fidelity. We use this readout to probe coherent dynamics and relaxation of the spin. This approach will enable quantum technologies based on a much broader range of atomic defects.", "author_names": [ "Mouktik Raha", "Songtao Chen", "Christopher M Phenicie", "Salim Ourari", "A Dibos", "Jeff D Thompson" ], "corpus_id": 198179803, "doc_id": "198179803", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Optical quantum nondemolition measurement of a solid state spin without a cycling transition", "venue": "", "year": 2019 }, { "abstract": "An ultrafast vector magneto optical Kerr effect (MOKE) microscope with integrated time synchronized electrical pulses, two dimensional magnetic fields, and low temperature capabilities is reported. The broad range of capabilities of this instrument allows the comprehensive study of spin orbital interaction driven magnetization dynamics in a variety of novel magnetic materials or heterostructures: (1) electrical pump and optical probe spectroscopy allows the study of current driven magnetization dynamics in the time domain, (2) two dimensional magnetic fields along with the vector MOKE microscope allow the thorough study of the spin orbital interaction induced magnetization re orientation in arbitrary directions, and (3) the low temperature capability allows us to explore novel materials/devices where emergent phenomena appear at low temperature. We discuss the details and challenges of this instrument development and integration and present two datasets that demonstrate and benchmark the capabilities of this instrument: (a) a room temperature time domain study of current induced magnetization dynamics in a ferromagnet/heavy metal bilayer and (b) a low temperature quasi static polar MOKE study of the magnetization of a novel compensated ferrimagnet.", "author_names": [ "Yu-Sheng Ou", "Xinran Zhou", "Rasoul Barri", "Stephanie Law", "John Q Xiao", "Matthew F Doty" ], "corpus_id": 215405957, "doc_id": "215405957", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Development of a system for low temperature ultrafast optical study of three dimensional magnon and spin orbital torque dynamics.", "venue": "The Review of scientific instruments", "year": 2020 }, { "abstract": "Ultrafast Optical Control of Complex Quantum Materials Stefan Kaiser MPI Universitat Stuttgart Antrittsvorlesung It is well known fact that various phase transitions in condensed matter can by triggered by external parameters such as temperature, pressure, electric field or magnetic field. Finding systems that show phase transitions triggered by external stimulation of light became a particular interesting field of research. Advanced nonlinear optical methods such as ultra broad band pump probe spectroscopy open new ways of controlling ultrafast dynamics in complex solid state materials on unprecedented timescales. In quantum materials, finding new ways of manipulating the complex interplay of electronic phases or effectively tuning electronic interactions opens new avenues in controlling physical properties and designing new functionalities. Some of the most remarkable examples are stabilizing a transient superconducting state far above its equilibrium critical temperature. I will discuss how we investigate different scenarios like the balancing between competing phases triggered by ultra short light pulses or possibilities of dynamical stabilization of new states of matter in periodically driven light fields; thereby highlighting new methods we develop and new classes of materials that we explore. Gastgeber: Prof. Martin Dressel, Universitat Stuttgart, Telefon: 0711 685 64946", "author_names": [ "Stefan Kaiser" ], "corpus_id": 139904820, "doc_id": "139904820", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Ultrafast Optical Control of Complex Quantum Materials", "venue": "", "year": 2018 }, { "abstract": "The spatial alignment of the crystallographic axes of single colloidal quantum dots is determined by purely optical means. This capability allows maximizing the Zeeman interaction in a magnetic field which is vital e.g. for efficient and ultrafast single photon amplification.", "author_names": [ "Pascal Gumbsheimer", "Christopher Hinz", "Y Behovits", "Florian Werschler", "C Traum", "Denis V Seletskiy", "Alfred Leitenstorfer" ], "corpus_id": 51976399, "doc_id": "51976399", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "All Optical Determination of 3 Dimensional Alignment of Crystal Axis of Single Colloidal Quantum Dots for Control of Ultrafast Spin Dynamics", "venue": "2018 Conference on Lasers and Electro Optics (CLEO)", "year": 2018 }, { "abstract": "In order to have a better understanding of ultrafast electrical control of exchange interactions in multi orbital systems, we study a two orbital Hubbard model at half filling under the action of a time periodic electric field. Using suitable projection operators and a generalized time dependent canonical transformation, we derive an effective Hamiltonian which describes two different regimes. First, for a wide range of non resonant frequencies, we find a change of the bilinear Heisenberg exchange J_{\\textrm{ex}}Jex that is analogous to the single orbital case. Moreover we demonstrate that also the additional biquadratic exchange interaction B_{\\textrm{ex}}Bex can be enhanced, reduced and even change sign depending on the electric field. Second, for special driving frequencies, we demonstrate a novel spin charge coupling phenomenon enabling coherent transfer between spin and charge degrees of freedom of doubly ionized states. These results are confirmed by an exact time evolution of the full two orbital Mott Hubbard Hamiltonian.", "author_names": [ "M M S Barbeau", "Martin Eckstein", "Mikhail I Katsnelson", "Johan H Mentink" ], "corpus_id": 55380290, "doc_id": "55380290", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "Optical control of competing exchange interactions and coherent spin charge coupling in two orbital Mott insulators", "venue": "SciPost Physics", "year": 2019 }, { "abstract": "Electron and spin dynamics of strongly correlated NdNiO3 are investigated across the metal insulator transition with ultrafast optical spectroscopy at different temperatures, pump laser fluences, and laser polarizations. Transient differential reflectivity measurements on the insulating phase NdNiO3 show two characteristic electronic decay processes. The slow decay process, strongly dependent on coherent phonon excitation, is attributed to the electron phonon interaction, while the fast decay process, to the electron spin interaction. The temporal evolution of Kerr rotation reveals that net spin polarization can be induced by circularly polarized light in insulating NdNiO3 via electron excitation from the Ni t to e orbital, and two net spin polarizations with opposite directions are observed given the antiferromagnetic ordering in insulating NdNiO3. At the insulator to metal transition, the transient differential reflectivity reverses its sign; the metallic phase NdNiO3 also shows two characteristic electronic decay processes, a typical metallic decay processes and a slow decay process; the slow decay process is attributed to the interaction between electrons and the low frequency coherent phonons (2.45 THz) Our experiments demonstrate that the phase transition involves several processes upon continuous heating: the electron spin interaction disappears at 9 K below the transition temperature; at the transition temperature, NdNiO3 transitions into the metallic phase and the antiferromagnetic ordering transitions into the paramagnetic ordering; at the transition temperature, the structure of NdNiO3 changes from a monoclinic structure to a high temperature orthorhombic structure. Such a structure change results in the change in phonon vibrations, and subsequently, leads to the disappearance of the electron phonon interactions due to the insulating phase NdNiO3 and the emergence of other types of electron phonon interactions due to the metallic phase.", "author_names": [ "Weizheng Liang", "Huaming Hou", "Yuan Lin", "S N Luo" ], "corpus_id": 125471157, "doc_id": "125471157", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Ultrafast electron and spin dynamics of strongly correlated NdNiO3", "venue": "", "year": 2019 }, { "abstract": "Mesoscopic ensembles of qubits offer a platform for near term applications in quantum technologies, as well as for studying many body physics. Key in exploiting these systems is the ability to coherently control constituent qubits in a manner that leaves the quantum states of neighboring qubits unperturbed. Atom like emitters in solids [1] have emerged as a promising platform for computing, communications, and sensing. In particular, their long coherence times, coherent optical transitions, and the ability to couple to nearby long lived nuclear spins make them excellent candidates for building medium scale registers of coupled qubits.", "author_names": [ "Eric Bersin", "Michael P Walsh", "Sara L Mouradian", "Matthew E Trusheim", "Kevin Chen", "Tim Schroder", "D Englund" ], "corpus_id": 204819375, "doc_id": "204819375", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Multi Qubit Registers of Individually Addressable Solid State Defect Centers", "venue": "2019 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)", "year": 2019 } ]

[ { "abstract": "A new, dynamic, time domain, numerical model for external cavity lasers, based on the transmission line laser model (TLLM) is introduced. This is able to show the evolution of spectra from large signal modulated devices, even when the modulation pulsewidth is less than the external cavity round trip delay. The model is demonstrated using short and long dispersionless cavities. Results in the time and spectral domains are in agreement with those of previous theoretical and experimental work.", "author_names": [ "Arthur James Lowery" ], "corpus_id": 11957215, "doc_id": "11957215", "n_citations": 14, "n_key_citations": 0, "score": 1, "title": "New dynamic multimode model for external cavity semiconductor lasers", "venue": "", "year": 1989 }, { "abstract": "Long External Cavity Laser (L ECL) is a kind of new and promising type laser because of its dynamic single mode performance. In this paper, firstly, the theory model of L ECL is discussed; Secondly, the influence of coupling coefficient on the threshold gain of L ECL is studied based on equivalent external cavity theory; Thirdly, utilizing the theory of equivalent cavity length, combined rate equations, the high frequency response characteristic of L ECL is analyzed; Lastly, optical spectrums of L ECL on different grating peak reflectivity are obtained by experiment.", "author_names": [ "Chang Jian Qi", "Tonggang Zhao" ], "corpus_id": 111061470, "doc_id": "111061470", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The Theory and Experimental Study on the Long External Cavity Semiconductor Lasers", "venue": "", "year": 2014 }, { "abstract": "We investigate the dynamical stability of external cavity semiconductor lasers with deliberate tilt asymmetries. Experimentally observed low frequency self pulsations are explained by small signal analysis based on a new rateequation model that uses a time dependent effective reflectivity to include multiple feedback effects. We observe and explain the dependence of the self pulsation frequency on the strength and degree of asymmetry of the feedback, on the injection current, and on the external cavity length. These results are important in interpreting instabilities, chaos, and other complex dynamical phenomena in external cavity semiconductor lasers.", "author_names": [ "J D Park", "Dongsun Seo", "John G McInerney", "Gregory C Dente", "Marek Osinski" ], "corpus_id": 37541681, "doc_id": "37541681", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Low frequency self pulsations in asymmetric external cavity semiconductor lasers due to multiple feedback effects.", "venue": "Optics letters", "year": 1989 }, { "abstract": "Vertical cavity surface emitting laser (VCSEL) constructions capable of direct modulation at bit rates in excess of 40 GBit/s have attracted considerable attention for future high speed long and medium haul networks. The two main approaches to realising this goal are, firstly, the improvement in the direct current modulation laser performance, with 40 GBit/s direct modulation having been demonstrated recently, and, secondly, using advanced modulation schemes. These, in turn, fall into two major categories: firstly, modulation of the photon lifetime in the cavity as an alternative to current modulation, and, secondly, current modulation enhanced by photon photon resonance in a specialised laser structure (e.g. using an external cavity [1] or a laser array [2] Theoretical models describing both of these solutions have been developed, but appear to have certain limitations which will be discussed later in the thesis, and no systematic analysis and comparison of modulation properties of advanced modulation scheme had been performed, to the best of my knowledge. This was the purpose of my PhD project. In order to understand the performance of the photon lifetime modulation for Compound Vertical Cavity Surface Emitting Semiconductor Lasers more accurately, a model involving careful analysis of both amplitude and frequency (phase) of laser emission, as well as the spectrally selective nature of the laser cavity, is required. We have developed such a model and used it to describe the laser operation and predict the performance beyond current experimental conditions in both large and small signal modulation regimes for the first time according to our knowledge. Finally, we studied the alternative method of ultrafast modulation of VCSELs, consisting of current modulation enhanced by photon photon resonance. The analysis concentrates on the version of the method involving an in plane integrated extended cavity. A new model is developed to overcome the limitations of existing models and to allow better understanding of the dynamic of the in plane laser cavity.", "author_names": [ "Fahad Albugami" ], "corpus_id": 115352161, "doc_id": "115352161", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Modelling and design of advanced high speed vertical cavity semiconductor lasers", "venue": "", "year": 2017 }, { "abstract": "Speckle formation is a limiting factor when using coherent sources for imaging and sensing, but can provide useful information about the motion of an object. Illumination sources with tunable spatial coherence are therefore desirable as they can offer both speckled and speckle free images. Efficient methods of coherence switching have been achieved with a solid state degenerate laser, and here we demonstrate a semiconductor based degenerate laser system that can be switched between a large number of mutually incoherent spatial modes and few mode operation. Our system is designed around a semiconductor gain element, and overcomes barriers presented by previous low spatial coherence lasers. The gain medium is an electrically pumped vertical external cavity surface emitting laser (VECSEL) with a large active area. The use of a degenerate external cavity enables either distributing the laser emission over a large ~1000) number of mutually incoherent spatial modes or concentrating emission to few modes by using a pinhole in the Fourier plane of the self imaging cavity. To demonstrate the unique potential of spatial coherence switching for multimodal biomedical imaging, we use both low and high spatial coherence light generated by our VECSEL based degenerate laser for imaging embryo heart function in Xenopus, an important animal model of heart disease. The low coherence illumination is used for high speed (100 frames per second) speckle free imaging of dynamic heart structure, while the high coherence emission is used for laser speckle contrast imaging of the blood flow.", "author_names": [ "Hui Cao", "Sebastian Knitter", "Changgeng Liu", "Brandon Redding", "Mustafa K Khokha", "Michael A Choma" ], "corpus_id": 125996666, "doc_id": "125996666", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Coherence switching of a vertical cavity semiconductor laser for multimode biomedical imaging (Conference Presentation)", "venue": "BiOS", "year": 2017 }, { "abstract": "Laser technology is finding applications in areas such as high resolution spectroscopy, radar lidar, velocimetry, or atomic clock where highly coherent tunable high power light sources are required. Offering such performances in the Near and Middle IR range, GaAs and Sb based Vertical External Cavity Surface Emitting Laser (VeCSEL) technologies [1] seem to be a well suited path to meet the required specifications of demanding applications. Here, we report on the realization of industry ready packaged low noise single frequency VeCSEL devices emitting in the 0.8 1.1 um and 2 2.5 um spectral range with high performances thanks to a combination of power coherence wavelength tunability and compactness. A fundamental study of the non linear multimode laser dynamics was carried out to avoid dynamic phase amplitude instability. We demonstrate both experimentally and theoretically the existence of a deterministic dynamics of the laser field, with either a regular multimode non stationary regime, or a route to robust single frequency operation. Integration of flat photonics technology allows the realization of devices emitting new coherent light states (VORTEX or dual frequency lasers) for applications to optical tweezers or THz emission, for instance.", "author_names": [ "Baptiste Chomet", "S Denet", "V Lecocq", "L Ferrieres", "Mikhael Myara", "Laurent Cerutti", "Gregoire Beaudoin", "Isabelle Sagnes", "Arnaud Garnache" ], "corpus_id": 139285386, "doc_id": "139285386", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Industrial low noise tunable integrated semiconductor laser: dynamic instability and route to single frequency operation", "venue": "LASE", "year": 2019 }, { "abstract": "The optical feedback dynamics of two multimode InAs/GaAs quantum dot lasers emitting exclusively on sole ground or excited lasing states is investigated. The transition from longto short delay regimes is analyzed, while the boundaries associated to the birth of periodic and chaotic oscillations are unveiled to be a function of the external cavity length. The results show that depending on the initial lasing state, different routes to chaos are observed. These results are of importance for the development of isolator free transmitters in short reach networks. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement OCIS codes: (140.5960) Semiconductor lasers; (250.0250) Optoelectronics; (190.3100) Instabilities and chaos. References and links 1. C. F. Lam, H. Liu, and R. Urata, \"What devices do data centers need?\" in Optical Fiber Communications Conference and Exhibition (OFC) of 2014 OSA Technical Digest Series (Optical Society of America, 2014) paper M2K.5. 2. Cisco white paper, \"The Zettabyte Era: Trends and Analysis\" (Cisco, 2016) 3. D. Bimberg, \"Quantum dot based nanophotonics and nanoelectronics,\" Electron. Lett. 44, 390 (2008) 4. G. Eisenstein and D. Bimberg, eds. Green Photonics and Electronics (Springer, 2017) 5. M. T. Crowley, N. A. Naderi, H. Su, F. Grillot, and L. F. Lester, \"GaAs Based Quantum Dot Lasers,\" in Advances in Semiconductor Lasers, J. J. Coleman, A. Bryce, and C. Jagadish, eds. (Academic Press, 2012) pp. 371 417 6. M. Grundmann, ed. Nano Optoelectronics, NanoScience and Technology (Springer, 2002) 7. K. Nishi, K. Takemasa, M. Sugawara, and Y. Arakawa, \"Development of quantum dot lasers for data com and silicon photonics applications,\" IEEE J. Sel. Topics Quantum Electron. 23, 1 7 (2017) 8. A. Y. Liu, S. Srinivasan, J. Norman, A. C. Gossard, and J. E. Bowers, \"Quantum dot lasers for silicon photonics,\" Photonics Res. 3, B1 (2015) 9. S. Chen, W. Li, J. Wu, Q. Jiang, M. Tang, S. Shutts, S. N. Elliott, A. Sobiesierski, A. J. Seeds, I. Ross, P. M. Smowton, and H. Liu, \"Electrically pumped continuous wave III V quantum dot lasers on silicon,\" Nat. Photonics 10, 307 311 (2016) 10. Ranovus Inc. \"Ranovus announces availability of world's first quantum dot multi wavelength laser and silicon photonics platform technologies to create a new cost and power consumption paradigm for DCI market,\" (Ranovus, 2016) http:/ranovus.com/worlds first quantum dot multi wavelength laser and silicon photonics platformtechnologies for dci market/ 11. Y. Urino, N. Hatori, K. Mizutani, T. Usuki, J. Fujikata, K. Yamada, T. Horikawa, T. Nakamura, and Y. Arakawa, \"First demonstration of athermal silicon optical interposers with quantum dot lasers operating up to 125 *C,\" J. Lightw. Technol. 33, 1223 1229 (2015) 12. N. Zhuo, J. C. Zhang, F. J. Wang, Y. H. Liu, S. Q. Zhai, Y. Zhao, D. B. Wang, Z. W. Jia, Y. H. Zhou, L. J. Wang, J. Q. Liu, S. M. Liu, F. Q. Liu, Z. G.Wang, J. B. Khurgin, and G. Sun, \"Room temperature continuous wave quantum dot cascade laser emitting at 7.2 mm,\" Opt. Express 25, 13807 13815 (2017) Vol. 26, No. 2 22 Jan 2018 OPTICS EXPRESS 1743 #318053 https:/doi.org/10.1364/OE.26.001743 Journal (c) 2018 Received 19 Dec 2017; accepted 8 Jan 2018; published 16 Jan 2018 13. A. Spott, E. J. Stanton, N. Volet, J. D. Peters, J. R. Meyer, and J. E. Bowers, \"Heterogeneous integration for mid infrared silicon photonics,\" IEEE J. Sel. Top. Quantum Electron. 23, 1 10 (2017) 14. D. O'Brien, S. Hegarty, G. Huyet, J. McInerney, T. Kettler, M. Laemmlin, D. Bimberg, V. Ustinov, A. Zhukov, S. Mikhrin, and A. Kovsh, \"Feedback sensitivity of 1.3 mm InAs/GaAs quantum dot lasers,\" Electron. Lett. 39, 1819 (2003) 15. K. Mizutani, K. Yashiki, M. Kurihara, Y. Suzuki, Y. Hagihara, N. Hatori, T. Shimizu, Y. Urino, T. Nakamura, K. Kurata, and Y. Arakawa, \"Optical I/O core transmitter with high tolerance to optical feedback using quantum dot laser,\" in 2015 European Conference on Optical Communication (ECOC) (2015) paper 0263. 16. D. Arsenijevic and D. Bimberg, \"Quantum dot lasers for 35 gbit/s pulse amplitude modulation and 160 gbit/s differential quadrature phase shift keying,\" Proc. SPIE 9892, 9892 (2016) 17. C. Wang, B. Lingnau, K. Ludge, J. Even, and F. Grillot, \"Enhanced dynamic performance of quantum dot semiconductor lasers operating on the excited state,\" IEEE J. Quantum Electron. 50, 723 731 (2014) 18. Z. R. Lv, H. M. Ji, X. G. Yang, S. Luo, F. Gao, F. Xu, and T. Yang, \"Large Signal Modulation Characteristics in the Transition regime for two state lasing quantum dot lasers,\" Chinese Phys. Lett. 33, 124204 (2016) 19. B. J. Stevens, D. T. D. Childs, H. Shahid, and R. A. Hogg, \"Direct modulation of excited state quantum dot lasers,\" Appl. Phys. Lett. 95, 061101 (2009) 20. D. Arsenijevic, A. Schliwa, H. Schmeckebier, M. Stubenrauch, M. Spiegelberg, D. Bimberg, V. Mikhelashvili, and G. Eisenstein, \"Comparison of dynamic properties of groundand excited state emission in p doped InAs/GaAs quantum dot lasers,\" Appl. Phys. Lett. 104, 181101 (2014) 21. F. Grillot, B. Dagens, J. G. Provost, H. Su, and L. F. Lester, \"Gain compression and above threshold linewidth enhancement factor in 1.3 mm InAs GaAs quantum Dot lasers,\" IEEE J. Quantum Electron. 44, 946 951 (2008) 22. F. Zubov, M. Maximov, E. Moiseev, A. Savelyev, Y. Shernyakov, D. Livshits, N. Kryzhanovskaya, and A. Zhukov, \"Observation of zero linewidth enhancement factor at excited state band in quantum dot laser,\" Electron. Lett. 51, 1686 1688 (2015) 23. C. Mesaritakis, C. Simos, H. Simos, S. Mikroulis, I. Krestnikov, E. Roditi, and D. Syvridis, \"Effect of optical feedback to the ground and excited state emission of a passively mode locked quantum dot laser,\" Appl. Phys. Lett. 97, 061114 (2010) 24. A. Rohm, B. Lingnau, and K. Ludge, \"Ground state modulation enhancement by two state lasing in quantum dot laser devices,\" Appl. Phys. Lett. 106, 1 6 (2015) 25. F. Grillot, N. A. Naderi, J. B. Wright, R. Raghunathan, M. T. Crowley and L. F. Lester, \"A dual mode quantum dot laser operating in the excited state,\" Appl. Phys. Lett. 99, 1110 1113 (2011) 26. J. D. Walker, D. M. Kuchta, and J. S. Smith, \"Wafer scale uniformity of vertical cavity lasers grown by modified phase locked epitaxy technique,\" Electron. Lett. 29, 239 240 (1993) 27. H. Huang, D. Arsenijevic, K. Schires, T. Sadeev, D. Bimberg, and F. Grillot, \"Multimode optical feedback dynamics of InAs/GaAs quantum dot lasers emitting on different lasing states,\" AIP Adv. 6, 125114 (2016) 28. A. Kovsh, N. Maleev, A. Zhukov, S. Mikhrin, A. Vasil'ev, E. Semenova, Y. Shernyakov, M. Maximov, D. Livshits, V. Ustinov, N. Ledentsov, D. Bimberg, and Z. Alferov, \"InAs/InGaAs/GaAs quantum dot lasers of 1.3 mm range with enhanced optical gain,\" J. Cryst. Growth 251, 729 736 (2003) 29. O. Stier, M. Grundmann, and D. Bimberg, \"Electronic and optical properties of strained quantum dots modeled by 8 band k*p theory,\" Phys. Rev. B 59, 5688 (1999) 30. A. Schliwa, M. Winkelnkemper, and D. Bimberg, \"Few particle energies versus geometry and composition of InxGa1x As/GaAs self organized quantum dots,\" Phys. Rev. B 79, 075443 (2009) 31. N. Schunk and K. Petermann, \"Stability analysis for laser diodes with short external cavities,\" IEEE Photon. Technol. Lett. 1, 49 51 (1989) 32. J. Ohtsubo, Semiconductor Lasers: Stability, Instability and Chaos, Springer Series in Optical Sciences (Springer, 2010) 33. J. P. Toomey, D. M. Kane, C. McMahon, A. Argyris, and D. Syvridis, \"Integrated semiconductor laser with optical feedback: transition from short to long cavity regime,\" Opt. Express 23, 18754 (2015) 34. N. Gavra and M. Rosenbluh, \"Behavior of the relaxation oscillation frequency in vertical cavity surface emitting laser with external feedback,\" J. Opt. Soc. Am. B 27, 2482 2487 (2010) 35. M. Stubenrauch, G. Stracke, D. Arsenijevic, A. Strittmatter, and D. Bimberg, \"15 Gb/s index coupled distributed feedback lasers based on 1.3 mm InGaAs quantum dots,\" Appl. Phys. Lett. 105, 011103 (2014)", "author_names": [ "H Uang", "IN LYU-CHIHL", "Christian Hen", "D Ejan A Rsenijevic", "D Ieter B Imberg", "F Rederic G Rillot" ], "corpus_id": 49657772, "doc_id": "49657772", "n_citations": 5, "n_key_citations": 1, "score": 0, "title": "Multimode optical feedback dynamics in InAs GaAs quantum dot lasers emitting exclusively on ground or excited states transition from short to long delay regimes", "venue": "", "year": 2018 }, { "abstract": "Summary form only given. Recent advances in monolithic integration technology have led to a number of new monolithic active and passive optical devices based on interferometric waveguide constructions, such as monolithic TDM and WDM multiplexers and demultiplexers. Here, we propose to apply the interferometric principle to design of semiconductor laser structures, resulting in parallel compound cavities (PCC) Whilst the idea of such a cavity allows numerous permutations, here we concentrate on the fractal dimensional geometry in which light from two or more parallel waveguides is combined by means of a coupler (of either directional, Y type, or multimode interference (MMI) type) into a single output waveguide. We theoretically analyse these structures using a model of their threshold, spectral and dynamical. Properties based on decomposition into modes of the active compound cavity and analysis of complex eigenfrequencies of these modes.", "author_names": [ "Eugene A Avrutin", "A Catrina Bryce", "Craig James Hamilton", "Dan A Yanson", "John M Arnold", "John H Marsh" ], "corpus_id": 119416974, "doc_id": "119416974", "n_citations": 4, "n_key_citations": 1, "score": 0, "title": "Analysis of monolithic parallel compound cavity semiconductor lasers for high brightness, single frequency, and short pulse operation", "venue": "", "year": 1999 }, { "abstract": "The dynamic response of a single mode semiconductor laser coupled to a passive external cavity is analysed through the numerical solution of its rate equations. A complete transmission system is simulated using a model derived from the analogy with transmission lines. Although the optical feedback decreases the damping coefficient of the relaxation oscillations, it causes a considerable reduction on the frequency chirp, always present in intensity modulation. In order to analyse the performance of the external cavity laser under realistic conditions, an optical pulse is propagated through a dispersive fiber and filtered in a receiver. The investigation of pulse broadening and the eye diagrams indicate that the system capacity can be increased by a factor of 2 by using an external resonator. Introduction A great deal of work has been done towards the enhancement of communication system capacity which has led, among other consequences, to the study and implementation of coherent systems. To implement such systems the performance of conventional semiconductor lasers has to be improved, specially regarding the spectral linewidth. DFB and DBR lasers although having small linewidth still do not achieve the necessary requirements. However, the coupling of a semiconductor laser to an external cavity can represent a 1000 fold spectral linewidth reduction [l] Another major problem always present on high bit rates intensity modulation lightwave systems is the frequency chirp. In this case the modulation of the carrier density induces a variation on the refractive index which causes a change in the emission frequency. Here, since the external cavity resonant frequency is independent on carrier flutuations the coupled configuration ECSL (external cavity semiconductor laser) reduces chirp considerably. Therefore external cavity lasers are of interest for coherent and intensity modulation optical systems. In this paper, a complete time domain analysis of the ECSL performance is presented. The study is based on the numerical solution of the ECSL rate equations. On deriving these equations, a new approach is used, based on an equivalency with transmission lines. It consists of the analysis of the propagating field components inside the diode leading to the system rate equations [4] that are numerically solved. A similar approach was used in [2] where different assumptions led to an analytical solution. Also, the assumptions made in order to derive and solve the system of rate equations and the numerical solution itself are discussed. The last section is divided in two parts. First, the response of the ECSL", "author_names": [ "L E M de Barros", "E Moschin", "Rui Fragassi Souza" ], "corpus_id": 111255719, "doc_id": "111255719", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Dynamic Response Of External Cavity Semiconductor Laser A Multigigabit Per Second Transmission Simulation", "venue": "SBMO International Microwave Conference/Brazil,", "year": 1993 }, { "abstract": "As an active research field, the self mixing interferometry (SMI) based on semiconductor lasers (SLs) is a highly promising and emerging technique for non contact sensing and parameter measurement of SLs. The basic structure of an SMI system consists of an SL, a lens and an external target. When a portion of reflected light from the target travels back to the laser cavity, a new lasing field is built up leading to both amplitude and phase modulations. The modulated output power is called a self mixing signal which carries the information of both the target and SL's feature parameters. Alpha factor, also known as linewidth enhancement factor, is one of the most important SL's feature parameters. It characterizes the characteristics of SLs, such as the linewidth, the chirp, the injection lock range and the dynamic performances. This paper presents a new method for retrieving alpha factor of SLs by making use of a self mixing interference (SMI) waveform. According to the well known Lang Kobayashi (L K) theory, the SMI waveform is shaped by multiple parameters, including the alpha, the optical feedback level factor (denoted as C) and other parameters related to the oscillation of the external target. In this work, we build a new equation based on the SMI model derived from the L K theory, which can be used to calculate the alpha value. In the existing SMI based methods for measuring the alpha factor, the optical feedback level C is limited within a certain narrow range. The proposed method is able to relieve this limitation. The associated simulations and experiments are carried out for verifying the proposed method.", "author_names": [ "Yan Gao", "Yanguang Yu", "Jiangtao Xi" ], "corpus_id": 110384641, "doc_id": "110384641", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Retreving alpha factor of semiconductor lasers from a self mixing interference waveform", "venue": "Photonics Asia", "year": 2012 } ]

[ { "abstract": "There is an increasing need for highly accurate 3D inspection and measurement capabilities for applications in SMT, semiconductor and metrology markets. 3D Multiple Reflection Suppression (MRS) sensor technology has been effectively combined with Automated Optical Inspection for several years and is now being utilized for many SPI applications such as microelectronics and sub 100 micron solder paste deposits and other challenging applications, like packaging, automotive, medical and other applications with stringent quality requirements. In addition to inspection, there is an increasing need to capture coordinate measurements inline. Phase shift profilometry (PSP) is widely used for 3D automated optical inspection (AOI) by electronics manufacturers assembling printed circuit boards (PCB) using automated surface mount technologies (SMT) Conventional PSP measurements are significantly challenged by inaccuracies caused by multiple reflections between surfaces on the inspected object. Multiple Reflection Suppression (MRS) sensor technology addresses this challenge. The sensor's unique optical architecture and the system's proprietary image fusing and processing algorithms provide fast, accurate 3D characterization capabilities that are well suited to other important applications, including solder paste inspection (SPI) and measurements typically performed by coordinate measurement machines (CMM) Coordinate measurements can now be attained in seconds, rather than the hours or days it would take a traditional coordinate measurement machine. MRS sensor technology provides significant advantages in speed, accuracy and resolution over the alternate technologies. This technology is a key building block for achieving high accuracy at production speed for Automated Optical Inspection (AOI) Solder Paste Inspection (SPI) and Coordinate Measurement (CMM) applications.", "author_names": [ "Dick Johnson", "John Hoffman" ], "corpus_id": 145042032, "doc_id": "145042032", "n_citations": 0, "n_key_citations": 0, "score": 2, "title": "Fast Accurate 3 D Sensor Technology for Automated Optical Inspection Solder Paste Inspection and Coordinate Measurements", "venue": "", "year": 2018 }, { "abstract": "The process of printing and inspecting solder paste deposits in Printed Circuit Boards (PCB) involves a very large number of variables (more than 30000 can be found in 3D inspection of high density PCBs) State of the art Surface Mount Technology (SMT) production lines rely on 100% inspection of all paste deposits for each PCB produced. Specification limits for Area, Height, Volume, Offset X and Offset Y have been defined based on detailed and consolidated studies. PCBs with paste deposits failing the defined criteria, are proposed to be rejected.", "author_names": [ "Pedro Delgado", "Cristina Martins", "Ana Cristina Braga", "Claudia Barros", "Isabel Delgado", "Carlos Marques", "Paulo Sampaio" ], "corpus_id": 49695510, "doc_id": "49695510", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Benefits of Multivariate Statistical Process Control Based on Principal Component Analysis in Solder Paste Printing Process Where 100% Automatic Inspection Is Already Installed", "venue": "ICCSA", "year": 2018 }, { "abstract": "The growth of the electronics industry led to a need for efficient methods of testing and validation of printed circuit boards (PCB) It is necessary to identify defects that might appear in a component in early production stages. This task may be performed by automatic inspection systems, showing advantages in speed, accuracy and repeatability, over human inspection. This paper describes a visual inspection system that is able to detect solder paste deposition defects on a PCB. The PCB image is analysed to segment the areas with solder paste and then, by comparing with reference data from the PCB design files, defects are identified, either because of missing or excess solder. The system is based on low cost components, namely a Raspberry Pi Compute Module and two Raspberry Pi v2 cameras. Experimental tests performed with the prototype, regarding the PCB defect detection and execution time, allowed to conclude the system can aid human visual inspection in a production line.", "author_names": [ "Guilherme B F Paulo", "Luis Perdigoto", "Sergio M M Faria" ], "corpus_id": 235207668, "doc_id": "235207668", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Automatic visual inspection system for solder paste deposition in PCBs", "venue": "2021 Telecoms Conference (ConfTELE)", "year": 2021 }, { "abstract": "With the explosion in the electronics market, PCB manufacturing has taken a very important place. The manufacturers use Gerber file as the only reference for PCB drawing since it gives the most accurate details of the solder pads to be etched on the PCB. Due to this feature of the Gerber file, we are using it in our proposal of PCB inspection mechanism. Gerber is a text file specifying the shape, dimensions and coordinates of the solder pads. Firstly, it is parsed so that these details could be extracted. From this information, the locations are tracked on the PCB image captured and the corresponding solder pad is cropped. The amount of solder paste applied is calculated by computing the area covered by the solder pad. Correspondingly, the ideal area, as given by the Gerber file is found out. Upon comparison of these two areas, the various PCB defects like deficient, excessive can be found out. Displacement faults are found out by calculating the centroid of the different solder pads on the PCB and comparing with the locations given by Gerber.", "author_names": [ "Vediya Sitaram Raghuvanshi", "A Burman", "Prashant P Bartakke", "Satish Deshpande" ], "corpus_id": 14819827, "doc_id": "14819827", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "PCB solder pad inspection mechanism using gerber file", "venue": "2016 International Conference on Communication and Signal Processing (ICCSP)", "year": 2016 }, { "abstract": "A solder printing inspection device (10) measures the volume of solder paste on a land on a PCB and sends inspection result information, including the measured volume, to an inspection data management device (102) From an image of the PCB after reflow, a solder attachment inspection device (30) extracts data on characteristics of the solder site being inspected, and said solder attachment inspection device communicates with the inspection data management device (102) to acquire the volume of solder paste at the point corresponding to the solder site being inspected, as measured by the solder printing inspection device (10) Said volume is then used to infer characteristics of nearby areas for which it is difficult to measure characteristics; the results of said inference are used together with the data on the abovementioned characteristics to compute the wetting height of the solder after reflow; and said height is classified as passing or failing.", "author_names": [ "Teng Jing Xin Ping", "Hong Zhi Sen", "Ke Qi Zhong Dao", "Gu Shang Chang Shen" ], "corpus_id": 140967052, "doc_id": "140967052", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Solder attachment inspection method, solder attachment inspection device, and pcb inspection system", "venue": "", "year": 2011 }, { "abstract": "A solder printing inspection device (10) measures the volume of solder paste on a land on a PCB, and a solder attachment inspection device (30) measures the wetting height of the solder after reflow. Said solder attachment inspection device (30) contains: an inspection program which contains a plurality of evaluation criteria for evaluating the measured wetting height; and a selection rule for selecting from said evaluation criteria. Said selection rule defines which evaluation criterion to select depending on the volume of solder paste on the solder site being inspected, as measured by the solder printing inspection device (10) The solder printing inspection device (10) reads, from an inspection data management device (102) the solder paste volume corresponding to the solder site being inspected and determines the aforementioned evaluation criterion on the basis thereof.", "author_names": [ "Teng Jing Xin Ping", "Hong Zhi Sen", "Ke Qi Zhong Dao", "Gu Shang Chang Shen" ], "corpus_id": 146305578, "doc_id": "146305578", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Solder attachment inspection method, pcb inspection system, and solder attachment inspection device", "venue": "", "year": 2011 }, { "abstract": "Quality inspection of PCB is a crucial stage in the assembly line as it provides an insight on whether the board works correctly or not. When the inspection is done manually, it is susceptible to human errors and is time consuming. The boards should thus be inspected at every stage of the assembly line and the process should be dynamic. This is achieved in this work through three crucial stages in the assembly line and by replacing the conventional manual inspection by using image processing to obtain a faster and more precise quality inspection. The solder paste inspection consists of preprocessing using blue plane conversion, comparing with the unsoldered board in blue color plane and post processing using overlay. The X ray inspection basically consists of preprocessing the captured image by RGB to gray conversion with thresholding, comparing with the expected image and post processing using overlay to show the shorts that has occurred along the assembly. The conformal coating inspection uses conversion of the blue intensity emitted off the board under UV light to RGB scale. Each of the algorithms were tested using 48 actual in production boards from Vinyas IT Pvt Ltd, a PCB assembly company based in Mysore. The processing time of the algorithms were found to be less than 2 seconds with an accuracy of 85.7% The system was also found to be cost eff ective over existing systems available in the market.", "author_names": [ "Dr P Madhan Kumar" ], "corpus_id": 221662068, "doc_id": "221662068", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Automated Quality Inspection of PCB Assembly Using Image Processing", "venue": "", "year": 2020 }, { "abstract": "In this paper, we introduce an automated Bayesian visual inspection framework for printed circuit board (PCB) assemblies, which is able to simultaneously deal with various shaped circuit elements (CEs) on multiple scales. We propose a novel hierarchical multi marked point process model for this purpose and demonstrate its efficiency on the task of solder paste scooping detection and scoop area estimation, which are important factors regarding the strength of the joints. A global optimization process attempts to find the optimal configuration of circuit entities, considering the observed image data, prior knowledge, and interactions between the neighboring CEs. The computational requirements are kept tractable by a data driven stochastic entity generation scheme. The proposed method is evaluated on real PCB data sets containing 125 images with more than 10 000 splice entities.", "author_names": [ "Csaba Benedek", "Oliver Krammer", "Mihaly Janoczki", "Laszlo Jakab" ], "corpus_id": 13194395, "doc_id": "13194395", "n_citations": 46, "n_key_citations": 4, "score": 0, "title": "Solder Paste Scooping Detection by Multilevel Visual Inspection of Printed Circuit Boards", "venue": "IEEE Transactions on Industrial Electronics", "year": 2013 }, { "abstract": "Detection of solder paste by image processing is a new approach in the solder paste inspection.image quality is one of the keys to ensure the accuracy of image detection.The image acquisition is a vital role for the protection of image quality.It's also a critical step in a series of processing steps to eventually obtain images useful information.This paper focuses on three main parameters of focal length,exposure and gain affecting the quality of solder paste image acquisition.The experimental demonstration of the reasonable range of the three main parameters of the focus,exposure and gain.As well as the functional relationship between shutter speed and gain.Providing a basis for the adjustment of solder paste image acquisition paramenters,but also laid the foundation for the follow up study for parameters adjustment automatically of the paste image acquisition.", "author_names": [ "Ye Hai" ], "corpus_id": 63839947, "doc_id": "63839947", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Solder Paste Image Acquisition Parameters of the PCB", "venue": "", "year": 2012 }, { "abstract": "Increased functional density and reduced input/output (I/O) spacing are the market trends in the electronics manufacturing industry. Industry reports indicate that approximately 50% 70% of soldering defects are attributed to the solder paste printing process for printed circuit board (PCB) assembly. Hence, after the printing process, a solder paste inspection (SPI) system is generally used to examine the amount of solder paste deposition. Effective selection of components and bonding pads during solder inspection is extremely important in achieving desired process cycle times and ensuring assembly yield. This paper uses the Mahalanobis Taguchi system to establish a systematic approach to determining guidelines for solder paste inspection. Among a total of 203 bonding pads on the board for a GPS product, the optimal model suggests that the solder deposition of 121 bonding pads be inspected. The reduction ratio is 40.4% and the feasibility of the proposed model is verified. Also, for those bonding pads to be inspected for their solder paste deposition, this study uses empirical data to define the specifications to effectively distinguish acceptable PCB samples from defective. The threshold is within the 100% capability for judgment of solder paste printing quality in the surface mount assembly process.", "author_names": [ "J C Huang" ], "corpus_id": 34747350, "doc_id": "34747350", "n_citations": 27, "n_key_citations": 0, "score": 0, "title": "Reducing Solder Paste Inspection in Surface Mount Assembly Through Mahalanobis Taguchi Analysis", "venue": "IEEE Transactions on Electronics Packaging Manufacturing", "year": 2010 } ]

[ { "abstract": "There is increasing interest in developing artificial systems that can mimic natural photosynthesis to directly harvest and convert solar energy into usable or storable energy resources. Photocatalysis, in which solar photons are used to drive redox reactions to produce chemical fuel, is the central process to achieve this goal. Despite significant efforts to date, a practically viable photocatalyst with sufficient efficiency, stability and low cost is yet to be demonstrated. It is often difficult to simultaneously achieve these different performance metrics with a single material component. The heterogeneous photocatalysts with multiple integrated functional components could combine the advantages of different components to overcome the drawbacks of single component photocatalysts. A wide range of heterostructures, including metal/semiconductor, semiconductor/semiconductor, molecule/semiconductor and multi heteronanostructures, have been explored for improved photocatalysts by increasing the light absorption, promoting the charge separation and transportation, enhancing the redox catalytic activity and prolonging the functional life time. The present review gives a concise overview of heterogeneous photocatalysts with a focus on the relationship between the structural architecture and the photocatalytic activity and stability.", "author_names": [ "Yongquan Qu", "Xiangfeng Duan" ], "corpus_id": 34580330, "doc_id": "34580330", "n_citations": 929, "n_key_citations": 4, "score": 1, "title": "Progress, challenge and perspective of heterogeneous photocatalysts.", "venue": "Chemical Society reviews", "year": 2013 }, { "abstract": "", "author_names": [ "Yongquan Qu", "Xiangfeng Duan" ], "corpus_id": 197082997, "doc_id": "197082997", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Progress, Challenge and Perspective of Heterogeneous Photocatalysts", "venue": "", "year": 2013 }, { "abstract": "This paper offers a perspective on inner sphere heterogeneous electron transfer reactions and electrocatalysis as it is applied to electrochemical energy conversion systems. Fundamental concepts and an overview of past approaches to studies of these types of reactions are discussed. A method for the discovery of new electrocatalysts (for example, ones for the oxygen reduction reaction) and photocatalysts (for solar energy conversion to fuels) based on scanning electrochemical microscopy is briefly described, as well as new surface interrogation techniques for quantifying intermediates.", "author_names": [ "Allen J Bard" ], "corpus_id": 10040726, "doc_id": "10040726", "n_citations": 225, "n_key_citations": 2, "score": 0, "title": "Inner sphere heterogeneous electrode reactions. Electrocatalysis and photocatalysis: the challenge.", "venue": "Journal of the American Chemical Society", "year": 2010 }, { "abstract": "Abstract This perspective provides an insight to the possibility of adopting hydrogen as a key energy carrier and fuel source, through Photocatalytic water splitting in the near future. The need of green and clean energy is increasing to overcome the growing demand of sustainable energy throughout globe, owing to CO2 emission using fossil fuels. To generate highly efficient and cost competitive hydrogen, the semiconductor based heterojunction nanomaterials have gained tremendous consideration as a promising way. Currently, the efficiency for hydrogen generation through UV Vis active photocatalysts is relatively low. The key issues are found to be poor separation of photogenerated electron/hole, less surface area, and low absorption region of electromagnetic spectrum. Such issues arise due to inappropriate band edge potentials and large bandgap of present catalyst. A lot of schemes has been devoted to design and fabricate efficient photocatalysts for improved photocatalytic performance in recent years. However, it seems still a challenge and imperative to greatly comprehend the fundamental aspects, photocatalysis and transfer mechanisms for complete deployment of electron/hole pairs. Further, to produce hydrogen to a larger extent through photocatalytic water splitting, the photocatalyst has been modified through co catalysts/dopants using numerous techniques including the Z scheme, hybridization, crystallinity, morphology, tuning of band edge positions, reduction of the band gap, surface structure etc. such that these heterogeneous photocatalysts may have ability to absorb enough light in the UV VIS IR region. This type of heterogeneous photocatalysts has the ability to improve the rate of efficiency for hydrogen evolution through absorption of sufficient light of solar spectrum and enhance the separation of charge carriers by inhibiting recombination of electron/hole pairs. We surmise that taking into account the aforesaid factors should support in scheming an efficient photocatalysts for hydrogen production through water splitting, eventually prompting technological developments in this field.", "author_names": [ "M B Tahir", "Abdullah M Asiri", "Tasmia Nawaz" ], "corpus_id": 224983128, "doc_id": "224983128", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "A perspective on the fabrication of heterogeneous photocatalysts for enhanced hydrogen production", "venue": "", "year": 2020 }, { "abstract": "Heterogeneous photocatalysis is a promising strategy for addressing the worldwide environmental pollution and energy shortage issues. However, unlike TiO2 with good photostability, the intrinsic drawback of photoinduced decomposition, i.e. photocorrosion, of semiconductors significantly challenges durable photocatalysis. In this review, the photocorrosion mechanisms of typical semiconductors and different characterization methods proposed for monitoring the photocorrosion process of semiconductor based composite photocatalysts are elaborated. Dedicated emphasis is put on the strategies for improving the anti photocorrosion property of semiconductor based photocatalysts, including modifying the crystal structure or morphology of semiconductors, doping with heteroatoms, hybridizing with various semiconductors and/or cocatalysts, and regulating the photocatalytic reaction conditions. Finally, we cast a personal prospect on the future development of the rational design of corrosion controlled semiconductor b.", "author_names": [ "Bo Weng", "Ming-Yu Qi", "Chuang Han", "Zi-Rong Tang", "Yi-Jun Xu" ], "corpus_id": 145911589, "doc_id": "145911589", "n_citations": 154, "n_key_citations": 0, "score": 0, "title": "Photocorrosion Inhibition of Semiconductor Based Photocatalysts: Basic Principle, Current Development, and Future Perspective", "venue": "ACS Catalysis", "year": 2019 }, { "abstract": "Abstract Ammonia is the second most produced chemical worldwide that makes up 80% of nitrogen based fertilisers, which have supported approximately 27% of the world's population over the last century. The Haber Bosch process, which is the main process for producing ammonia, is extremely energy intensive and consumes around 1% of the world's energy. Additionally, it requires hydrogen gas as a reactant that is produced via steam reforming which emits carbon dioxide as a by product. Over 500 million tonnes of ammonia are produced per year via industrial processes which required 3 5% of total natural gas consumption worldwide and also accounted for 2% global energy usage. Therefore, more sustainable processes, such as electrocatalysis and photocatalysis, using electrons and the transfer of protons has been investigated. This review covers the most state of the art technologies used to produce ammonia via electrocatalysis and photocatalysis by comparing different electrolyte systems and electrocatalysts as well as discussing issues with these methods and possible solutions. In addition, substantial improvements to electrocatalysts and photocatalysts as well as methods to prevent both the promotion of the hydrogen evolution reaction and the decomposition of ammonia at higher temperatures are reviewed. Challenges and perspectives are discussed.", "author_names": [ "Ke Wang", "Daniel J Smith", "Ying Zheng" ], "corpus_id": 139121169, "doc_id": "139121169", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "Electron driven heterogeneous catalytic synthesis of ammonia: Current states and perspective", "venue": "", "year": 2018 }, { "abstract": "Single atom photocatalysts have shown their compelling potential and arguably become the most active research direction in photocatalysis due to their fascinating strengths in enhancing light harvesting, charge transfer dynamics, and surface reactions of a photocatalytic system. While numerous comprehensions about the single atom photocatalysts have recently been amassed, advanced characterization techniques and vital theoretical studies are strengthening our understanding on these fascinating materials, allowing us to forecast their working mechanisms and applications in photocatalysis. In this review, we begin by describing the general background and definition of the single atom photocatalysts. A brief discussion of the metal support interactions on the single atom photocatalysts is then provided. Thereafter, the current available characterization techniques for single atom photocatalysts are summarized. After having some fundamental understanding on the single atom photocatalysts, their advantages and applications in photocatalysis are discussed. Finally, we end this review with a look into the remaining challenges and future perspectives of single atom photocatalysts. We anticipate that this review will provide some inspiration for the future discovery of the single atom photocatalysts, manifestly stimulating the development in this emerging research area.", "author_names": [ "Chao Gao", "Jingxiang Low", "Ran Long", "Tingting Kong", "Junfa Zhu", "Yujie Xiong" ], "corpus_id": 212751837, "doc_id": "212751837", "n_citations": 98, "n_key_citations": 0, "score": 0, "title": "Heterogeneous Single Atom Photocatalysts: Fundamentals and Applications.", "venue": "Chemical reviews", "year": 2020 }, { "abstract": "Visible light responsive photocatalytic technology holds great potential in water treatment to enhance purification efficiency, as well as to augment water supply through the safe usage of unconventional water sources. This review summarizes the recent progress in the design and fabrication of visible light responsive photocatalysts via various synthetic strategies, including the modification of traditional photocatalysts by doping, dye sensitization, or by forming a heterostructure, coupled with p conjugated architecture, as well as the great efforts made within the exploration of novel visible light responsive photocatalysts. Background information on the fundamentals of heterogeneous photocatalysis, the pathways of visible light responsive photocatalysis, and the unique features of visible light responsive photocatalysts are presented. The photocatalytic properties of the resulting visible light responsive photocatalysts are also covered in relation to the water treatment, i.e. regarding the photocatalytic degradation of organic compounds and inorganic pollutants, as well as photocatalytic disinfection. Finally, this review concludes with a summary and perspectives on the current challenges faced and new directions in this emerging area of research.", "author_names": [ "Shuying Dong", "Jing-lan Feng", "Maohong Fan", "Yunqing Pi", "Limin Hu", "Xiao Han", "Menglin Liu", "Jingyu Sun", "Jianhui Sun" ], "corpus_id": 94857280, "doc_id": "94857280", "n_citations": 579, "n_key_citations": 1, "score": 0, "title": "Recent developments in heterogeneous photocatalytic water treatment using visible light responsive photocatalysts: a review", "venue": "", "year": 2015 }, { "abstract": "Abstract In developing efficient heterogeneous photocatalysts, the design and fabrication of hierarchical semiconductors at the micro/nanometer scales have received much attention during the past decade due to their unique advantages in addressing the critical problems during photocatalysis. However, there are still many challenges in designing and constructing highly efficient hierarchical photocatalysts. Thus, in this review, we first systematically summarize and discusse the fundamentals and important interface engineering strategies of designing hierarchical photocatalysts, such as fabricating Z Scheme heterojunctions, constructing Schottky based heterojunctions, creating carbon based heterojunctions and designing multicomponent heterojunctions. Then, especially, the different surface modification approaches of hierarchical porous photocatalysts, including loading cocatalysts, exposing the reactive facets, introducing defects/heteroatoms, adding photosensitizers, are highlighted. Finally, the major conclusions are made regarding this promising class of heterogeneous photocatalysts, and some perspectives are given on its future development. Through studying the important advances on this topic, it may pave a new avenue for fabricating highly effective hierarchical semiconductors for various applications in photocatalysis, electrocatalysis, thermal catalysis and other fields.", "author_names": [ "Rongchen Shen", "Chuanjia Jiang", "Quanjun Xiang", "Jun Xie", "Xin Li" ], "corpus_id": 104340045, "doc_id": "104340045", "n_citations": 111, "n_key_citations": 0, "score": 0, "title": "Surface and interface engineering of hierarchical photocatalysts", "venue": "Applied Surface Science", "year": 2019 }, { "abstract": "Titanate nanostructures are of great interest for catalytic applications because their high surface area and cation exchange capacity create the possibility to achieve high metal dispersion. Ion exchange allows titanate nanostructures to incorporate metal adatoms in their framework. Consequently, the curved layers contain a large amount of defect sites, typically oxygen vacancies and Ti3+ centers, which can make them promising photocatalysts, because the defect sites can trap photoelectrons or holes extending the lifetime of the excited state. Due to the large amount of defects, titanate nanotubes (TNT) can stabilize sub nanosized gold clusters, presumably in Au25 form. This perspective summarizes the previous results obtained in the photocatalytic transformation of methane in which the size of gold nanoclusters plays an important role. Photocatalytic measurements revealed that methane is active towards photo oxidation. Methane transforms mainly into hydrogen and, to a lesser extent, to ethane and ethanol. Based on recent additional results, we stress here that gold clusters (Au25) may be directly involved in the photo induced reactions, namely in the direct activation of the methane/Au25d+ complex during irradiation. Another new finding is that gold nanoparticles supported on TNT exhibit high catalytic activity in CO2 hydrogenation. Our results revealed fundamental differences in the reaction schemes as the products of the two routes are CO (thermal process) and CH4 (photocatalytic route) indicating the importance of photogenerated electron hole pairs in the reaction. The presence of gold nanoparticles on the surface has been found to have multiple roles. On the one hand, gold in nano and sub nano sizes promotes the adsorption and scission of reactants, important for both types of reactions. On the other hand, the gold support interface forms a rectifying Schottky contact that helps in the separation of photogenerated carriers, thus improving the utilization of electrons and holes in the reduction and oxidation steps, respectively. Furthermore, gold ions (Au+ in the cationic sites of the titanate lattice promote the photocatalytic transformation of formate (which is one of the intermediates) thus advancing the reaction further towards the fully reduced product. The explored reaction schemes may pave the road towards novel catalytic materials that can solve challenges associated with the activation of CH4 and CO2 and thus contribute to green chemistry.Graphical Abstract", "author_names": [ "Janos T Kiss", "Akos Kukovecz", "Zoltan Konya" ], "corpus_id": 145864030, "doc_id": "145864030", "n_citations": 13, "n_key_citations": 0, "score": 0, "title": "Beyond Nanoparticles: The Role of Sub nanosized Metal Species in Heterogeneous Catalysis", "venue": "Catalysis Letters", "year": 2019 } ]

[ { "abstract": "The development of silicon semiconductor technology has produced breakthroughs in electronics from the microprocessor in the late 1960s to early 1970s, to automation, computers and smartphones by downscaling the physical size of devices and wires to the nanometre regime. Now, graphene and related two dimensional (2D) materials offer prospects of unprecedented advances in device performance at the atomic limit, and a synergistic combination of 2D materials with silicon chips promises a heterogeneous platform to deliver massively enhanced potential based on silicon technology. Integration is achieved via three dimensional monolithic construction of multifunctional high rise 2D silicon chips, enabling enhanced performance by exploiting the vertical direction and the functional diversification of the silicon platform for applications in opto electronics and sensing. Here we review the opportunities, progress and challenges of integrating atomically thin materials with silicon based nanosystems, and also consider the prospects for computational and non computational applications. Progress in integrating atomically thin two dimensional materials with silicon based technology is reviewed, together with the associated opportunities and challenges, and a roadmap for future applications is presented.", "author_names": [ "Deji Akinwande", "Cedric Huyghebaert", "Ching-Hua Wang", "Martha I Serna", "Stijn Goossens", "Lain-Jong Li", "H -S Philip Wong", "Frank H L Koppens" ], "corpus_id": 202762945, "doc_id": "202762945", "n_citations": 273, "n_key_citations": 0, "score": 1, "title": "Graphene and two dimensional materials for silicon technology", "venue": "Nature", "year": 2019 }, { "abstract": "", "author_names": [ "Andreas Bablich", "Satender Kataria", "Vikram Passi", "Max Christian Lemme" ], "corpus_id": 139679144, "doc_id": "139679144", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Graphene and Two Dimensional Materials: Extending Silicon Technology for the Future?", "venue": "", "year": 2017 }, { "abstract": "With the explosion of data in the information universe and the approaching of fundamental limits in silicon based flash memories, the exploration of new device architectures and alternative materials is necessary for next generation memory technology. Accordingly, emerging two dimensional (2D) material based memristive devices have attracted increasing attention due to their unique properties and great potential in flexible and wearable devices, and even neuromorphic computing systems. Herein, we provide an overview of the recent progress on memristive devices based on 2D materials beyond graphene. The device structures and choice of active materials and electrodes materials are summarized for various types of 2D material based memristive devices. Following the discussion and classification on the device performances and mechanisms, the challenges and perspectives on future research based on 2D materials are also presented.", "author_names": [ "Lei Zhang", "Tian Gong", "Huide Wang", "Zhinan Guo", "Han Zhang" ], "corpus_id": 195326281, "doc_id": "195326281", "n_citations": 42, "n_key_citations": 0, "score": 0, "title": "Memristive devices based on emerging two dimensional materials beyond graphene.", "venue": "Nanoscale", "year": 2019 }, { "abstract": "Two dimensional (2D) materials such as graphene and transition metal chalcogenides have been extensively studied because of their superior electronic and optical properties. Recently, 2D materials have shown great practical application in position sensitive detectors (PSDs) originating from the lateral photoelectrical effect of the materials or junctions. The high position sensitivity and ultrafast photoresponse of PSDs based on 2D materials, especially compatibility with Si technology, may enable diverse optoelectronic applications. In this review, recent studies of PSDs based on 2D materials are summarized, providing a promising route for high performance PSDs. Photodetectors that can monitor the location of an incident laser spot are useful for applications such as laser beam alignment and stabilization. While silicon p n or p i n detectors are commonly used, Chang Hu, Xianjie Wang and Bo Song from Harbin Institute of Technology in China, have now reviewed the advantages and capabilities of using a variety of 2D materials for performing this task. They report how junctions based on pairing graphene or molybdenum disulfide with silicon can result in positive sensitive detectors can be highly sensitive and offer an ultrafast response. The good performance is thought to be due to the high charge mobility and strong absorption of the 2D materials. Future challenges include extending the wavelength range of operation of such detectors beyond the visible to the near infrared and ultraviolet.", "author_names": [ "Chang Hu", "Xianjie Wang", "Bo Song" ], "corpus_id": 219310459, "doc_id": "219310459", "n_citations": 5, "n_key_citations": 0, "score": 0, "title": "High performance position sensitive detector based on the lateral photoelectrical effect of two dimensional materials", "venue": "Light, science applications", "year": 2020 }, { "abstract": "Two dimensional (2D) materials have attracted a lot of attention due to their optimal optoelectronic properties which are not found in the domain of silicon based electronic materials [1] The identification and characterization of 2D materials, especially differentiation of few layer from the bulk phase, is crucial for progress in materials research and manufacturing process development. Raman spectroscopy, and more specifically lowfrequency/THz Raman (r) analysis, has been recently introduced as a highly sensitive, real time and nondestructive analytical tool for these novel materials [2] The low wavenumber region which can aid the quantification of layers is usually not accessible with conventional Raman spectroscopy systems. Using volume holographic grating (VHG) based filter technology, we have developed a THzRaman (r) system that enables access to the low frequency region with a single stage spectrometer.", "author_names": [ "James T A Carriere", "Randy A Heyler", "Anjan Roy" ], "corpus_id": 165102809, "doc_id": "165102809", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "THz Raman(r) Characterization of Graphene and Two Dimensional Nanomaterials", "venue": "", "year": 2016 }, { "abstract": "In this work, side gate transistors based on graphene and molybdenum disulfide in comparison to their respective top or back gated devices are presented. The graphene devices were fabricated based on an all carbon technology on silicon carbide substrates, whereas the molybdenum disulfide transistors were fabricated using the exfoliation technique. The output characteristics are analyzed in terms of transconductance in dependence on the geometrical device properties for each material. It is shown that side gate transistors are able to reach the transconductances of conventional top gate MOSFETs and that this type of transistor can be used as a simple tool for material properties characterization.", "author_names": [ "B Hahnlein", "Mohamad Adnan Alsioufy", "Michael Lootze", "Heiko O Jacobs", "Frank Schwierz", "Jorg Pezoldt" ], "corpus_id": 94042154, "doc_id": "94042154", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Planar nanowire transistors from two dimensional materials", "venue": "", "year": 2016 }, { "abstract": "Currently, the prospects for replacing traditional materials with quasi two dimensional compounds based on transition metal dichalcogenides are actively being studied. The quasi two dimensional molybdenum disulfide MoS2, a semiconductor with a finite band gap, can be used either as a standalone material or as a part of layered heterostructures. When creating nanosized electronics elements based on such ultrathin materials, the application of an atomic layer etching technology is of key importance. In this paper, a brief description of the properties of MoS2 monolayers in comparison with graphene and the monolayers of hexagonal boron nitride is considered. On the basis of the results of computer simulation by means of a DFT (density functional theory) method, effects caused in the MoS2 monolayer by chlorine atoms and molecules widely used in the state of the art of atomic layer etching applied to silicon materials are demonstrated.", "author_names": [ "Ekaterina N Voronina", "Lev S Novikov", "T V Rakhimova" ], "corpus_id": 139223900, "doc_id": "139223900", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Properties and Potential Applications of Quasi Two Dimensional Molybdenum Disulfide for Nanoelectronic Elements", "venue": "Inorganic Materials: Applied Research", "year": 2018 }, { "abstract": "Silicene, the silicon analogue of graphene, represents a new class of two dimensional (2D) materials, which shares some of the outstanding physical properties of graphene. Furthermore, it has the advantage of being compatible with the current Si based technology. However, this 2D material is not stable and is quite prone to oxidation. The hydride terminated silicene, called silicane, is a more stable form of 2D silicon, if functionalized via, for example, the hydrosilylation reaction. In this work, the third order nonlinear optical (NLO) properties of two functionalized silicanes, namely hydride terminated silicon nanosheets (SiNS H) and 1 dodecene functionalized silicon nanosheets (SiNS dodecene) are accessed and compared to those of single layer graphene, under 35 ps, 532 and 1064 nm excitation. The present results show that the functionalized silicanes exhibit comparable and even higher NLO response than that of single layer graphene, making them strong competitors of graphene and very interesting candidates for future photonic and optoelectronic applications.", "author_names": [ "Michalis Stavrou", "Ioannis Papadakis", "Aristeidis Stathis", "Marc Julian Kloberg", "Josef Mock", "Tim Kratky", "Sebastian Gunther", "Bernhard Rieger", "Markus Becherer", "Alina Lyuleeva-Husemann", "Stelios Couris" ], "corpus_id": 231194030, "doc_id": "231194030", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Silicon Nanosheets versus Graphene Nanosheets: A Comparison of Their Nonlinear Optical Response.", "venue": "The journal of physical chemistry letters", "year": 2021 }, { "abstract": "Since the end of last century, the size of integrated devices has become smaller and smaller and semiconductor industry had been experiencing great challenge on Moore law. New materials and technology in semiconductor industry had become significant in the development in network communication and auto control. Finding new materials with excellent electronic natures other than silicon had been a hot spot of the research. With the discovery of Graphene, two dimensional material system becomes important in the research. Study the optical and electronic properties of two dimensional materials, especially the carrier mobility, which can help to design proper two dimensional materials. This paper introduces how the theoretical computation of the mobility for two dimensional materials was developed. Specifically, the Bloch theorem, density functional theory, the first principle calculation and deformation potentials theorem.", "author_names": [ "Song-Lin Li" ], "corpus_id": 139855833, "doc_id": "139855833", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "The Theoretical Calculation of Carrier Mobility for Two Dimensional Material", "venue": "", "year": 2018 }, { "abstract": "Submitted for the MAR14 Meeting of The American Physical Society Novel two dimensional silicon and germanium allotropes: a first principles study FLORIAN GIMBERT, CHI CHENG LEE, RAINER FRIEDLEIN, ANTOINE FLEURENCE, YUKIKO YAMADA TAKAMURA, TAISUKE OZAKI, School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST) 1 1 Asahidai, Nomi, Ishikawa 923 1292, Japan Graphene has been extensively studied but its integration into Si based device technologies is difficult. It has been recently predicted by first principles calculations that freestanding silicene and germanene, the counterparts of graphene made of Si and Ge atoms respectively, have graphene like electronic structure with a low buckled structure [1] So far, the models predicted by first principles calculations were not able to describe completely the experimental results. These difficulties tend to suggest a more complex phase diagram for freestanding silicene or for silicene on a substrate than the simple buckled phase. We report for the first time a novel two dimensional silicon and germanium allotropes, with a structure similar of that of MoS2 layer [2] After investigating a large range of lattice constants by first principles calculations with OpenMX code, we show that this structure is the ground state for freestanding two dimensional silicon and germanium layers instead of the usually considered low buckled silicene and germanene. [1] S. Cahangirov et al. Phys. Rev. Lett. 102, 236804 (2007) [2] B. Radisavljevic et al. Nature Nano. 6, 147 (2011) Florian Gimbert School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST) 1 1 Asahidai, Nomi, Ishikawa 923 1292, Japan Date submitted: 14 Nov 2013 Electronic form version 1.4", "author_names": [ "Chi-Cheng Lee", "Rainer Friedlein", "Antoine Fleurence", "Yukiko Yamada" ], "corpus_id": 4552277, "doc_id": "4552277", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Novel two dimensional silicon and germanium allotropes a first principles study FLORIAN GIMBERT", "venue": "", "year": 2013 } ]

[ { "abstract": "Similar to its popular older cousins the fullerene, the carbon nanotube, and graphene, the latest form of nanocarbon, the carbon nanodot, is inspiring intensive research efforts in its own right. These surface passivated carbonaceous quantum dots, so called C dots, combine several favorable attributes of traditional semiconductor based quantum dots (namely, size and wavelength dependent luminescence emission, resistance to photobleaching, ease of bioconjugation) without incurring the burden of intrinsic toxicity or elemental scarcity and without the need for stringent, intricate, tedious, costly, or inefficient preparation steps. C dots can be produced inexpensively and on a large scale (frequently using a one step pathway and potentially from biomass waste derived sources) by many approaches, ranging from simple candle burning to in situ dehydration reactions to laser ablation methods. In this Review, we summarize recent advances in the synthesis and characterization of C dots. We also speculate on their future and discuss potential developments for their use in energy conversion/storage, bioimaging, drug delivery, sensors, diagnostics, and composites.", "author_names": [ "Sheila N Baker", "Gary A Baker" ], "corpus_id": 21692287, "doc_id": "21692287", "n_citations": 3029, "n_key_citations": 18, "score": 1, "title": "Luminescent carbon nanodots: emergent nanolights.", "venue": "Angewandte Chemie", "year": 2010 }, { "abstract": "A single step hydrothermal mode of carbon nanodots (C dots) synthesis from house hold kitchen garbage such as snake gourd peel extract was successfully carried out. Characterisation of green synthesized C dots were accomplished using UV Visible and FTIR spectroscopy, Spectrofluorimetry and HRTEM. C dots exhibited an appreciable quantum yield of 28.6% Excitation dependent photoluminescence emission properties and pH sensitivity of C dots were also studied in detail. C dots exhibited strikingly selective detection of Fe3+ ions via fluorescence quenching mechanism. Linearity was obtained in a concentration range of 10 100 mM with detection limit of 0.398 mM in accordance with the Stern Volmer relation. The existence of oxygen containing functional moieties in luminescent C dots could be attributed to the effectual complexation between the metal ion and C dots. The selective sensing property of C dots towards Fe3+ ions provide avenue for biochemical analysis related to iron metabolism and diagnosis of anaemia.", "author_names": [ "Smrithi Sailaja Prasannakumaran Nair", "Nagaraju Kottam", "Prasanna Kumar S G" ], "corpus_id": 211169815, "doc_id": "211169815", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Green Synthesized Luminescent Carbon Nanodots for the Sensing Application of Fe3+ Ions", "venue": "Journal of Fluorescence", "year": 2020 }, { "abstract": "In the present investigation, the authors have adopted a simple and economical method for the synthesis of bright green photoluminescent carbon nanodots (CNDs) from tender coconut water via acid assisted ultrasonic route. Tender coconut water is used as a less expensive and eco friendly carbon precursor to produce well dispersed CNDs possessing a hybrid structural behaviour of both nanocrystalline and amorphous carbon phases. The monodispersed CNDs with spherical morphology and particle size (4 1 nm) were confirmed with the aid of high resolution transmission electron microscopy. The functional groups attached to CNDs are held responsible for the fluorescence nature and mono dispersion that were assessed using Fourier transform infrared spectroscopy. The green fluorescence nature of CNDs was evaluated at a maximum emission at 510 nm with an excitation wavelength of 450 nm, using ultraviolet visible absorption spectrum and photoluminescence spectra. The CNDs with a carbon core and chemical groups over their surface exhibited a fluorescence quantum yield of 60.18% The stability, low cost precursor, rapid reaction and uniform dispersion without chemical functionalisation makes these CNDs synthesised from tender coconut water more advantageous than other sources. This research mainly emphasis on synthesis and characterisation of CNDs with a detailed mechanism for CND formation.", "author_names": [ "P S Manoharan", "Sathish Chander Dhanabalan", "Muthulakshmi Alagan", "Santhoshbalaji Muthuvijayan", "Joice Sophia Ponraj", "Chandra Kishore Somasundaram" ], "corpus_id": 228994209, "doc_id": "228994209", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Facile synthesis and characterisation of green luminescent carbon nanodots prepared from tender coconut water using the acid assisted ultrasonic route", "venue": "", "year": 2020 }, { "abstract": "'Nanocarbon science' ignited interest owing to its substantial scope in biomedicine, energy and environment beneficial applications. Carbon dots (C dots) a multi faceted nanocarbon material, emerged as a homologue to graphene and henceforth geared extensive investigation both on its properties and applications. Eximious properties like excitation wavelength tunable fluorescence emission, up converted photoluminescence, photon induced electron transfer, low cytotoxicity, chiroptical behavior, high chemical and photostability set the ground for astounding applications of carbon dots. Abundant availability of raw 'green' precursors complementary to other molecular/graphitic precursors make them environmentally benign, inexpensive and ultimately 'nanomaterials of the current decade' This review focuses on the synthesis of carbon dots not only from natural sources but also from other carbonaceous precursors and contemplates the inherent but controversial properties. We also aim to garner the attention of readers to the recent progress achieved by C dots in one of its prestantious area of applications as nanosensors.", "author_names": [ "Nagaraju Kottam", "Smrithi S P" ], "corpus_id": 222301676, "doc_id": "222301676", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "'Luminescent carbon nanodots: Current prospects on synthesis, properties and sensing applications'", "venue": "Methods and applications in fluorescence", "year": 2020 }, { "abstract": "Carbon nanodots (C dots) are fascinating carbon materialsthat are attracting increasing interest because they possessdistinct benefits, such as chemical inertness, a lack of opticalblinking, low photobleaching, low cytotoxicity, and excellentbiocompatibility, compared with organic dyes and othersemiconductor nanodots with heavy metal cores.", "author_names": [ "Songnan Qu", "Xiaoyun Wang", "Qipeng Lu", "Xingyuan Liu", "Lijun Wang" ], "corpus_id": 13216045, "doc_id": "13216045", "n_citations": 870, "n_key_citations": 5, "score": 0, "title": "A biocompatible fluorescent ink based on water soluble luminescent carbon nanodots.", "venue": "Angewandte Chemie", "year": 2012 }, { "abstract": "Carbon nanodots (CDs) with a low cytotoxicity have been synthesized by one step microwave assisted pyrolysis of citric acid in the presence of various amine molecules. The primary amine molecules have been confirmed to serve dual roles as N doping precursors and surface passivation agents, both of which considerably enhanced the fluorescence of the CDs.", "author_names": [ "Xinyun Zhai", "Peng Zhang", "Chang-jun Liu", "Tao Bai", "Wenchen Li", "Liming Dai", "Wenguang Liu" ], "corpus_id": 3491885, "doc_id": "3491885", "n_citations": 682, "n_key_citations": 5, "score": 0, "title": "Highly luminescent carbon nanodots by microwave assisted pyrolysis.", "venue": "Chemical communications", "year": 2012 }, { "abstract": "The continuous synthesis in controlled gas flame reactors is here demonstrated as a very effective approach for the direct and easy production of structurally reproducible carbon nanodots. In this work, the design of a simple deposition system, inserted into the reactor, is introduced. A controlled flame reactor is employed in the present investigation. The system was optimized for the production of carbon nanoparticles including fluorescent nanocarbons. Blue and green fluorescent carbon could be easily separated from the carbon nanoparticles by extraction with organic solvents and characterized by advanced chemical (size exclusion chromatography and mass spectrometry) and spectroscopic analysis. The blue fluorescent carbon comprised a mixture of molecular fluorophores and aromatic domains; the green fluorescent carbon was composed of aromatic domains (10 20 aromatic condensed rings) bonded and/or turbostratically stacked together. The green fluorescent carbon nanodots produced in the flame reactor were insoluble in water but soluble in N methylpyrrolidinone and showed excitation independent luminescence. These results provide insights for a simple and controlled synthesis of carbon nanodots with specific and versatile features, which is a promising pathway for their use in quite different applicative sectors of bioimaging.", "author_names": [ "Carmela Russo", "Barbara Apicella", "Anna Ciajolo" ], "corpus_id": 203986718, "doc_id": "203986718", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Blue and green luminescent carbon nanodots from controllable fuel rich flame reactors", "venue": "Scientific Reports", "year": 2019 }, { "abstract": "Abstract Although several methods on the preparation of carbon nanodots (CNDs) emitting throughout the visible have been recently reported, in most of the processes the product suffers from inhomogeneity in size and shape limiting their impact. Here, we report the synthesis of undoped and nitrogen doped luminescent carbon nanodots by rapid pyrolysis using ordered mesoporous silica nanorods as confining templates. A rapid thermal decomposition (pyrolysis) within the confined dimensions of their pores leads to a highly uniform size distribution of CNDs with average sizes below 4 nm. These CNDs are synthesized in an extremely short time period (5 min of reaction) by immersion in a fluidized bed reactor that provides heating homogeneity and ensures fast heat transfer. In addition, a rapid release of the homogeneous CNDs can be easily achieved by a simple ultrasonication filtration step that prevents further chemical action on the mesoporous templates. The emission of both undoped and N doped CNDs in colloidal and solid state (with an efficiency of 1 5% originates from a combination of quantum confinement effects and the presence of oxidized surface states; N doping introduces resonant absorption states which participate in emission. Furthermore, we present a simple model to describe the excitation dependent/ independent mechanism of carbon nanodots.", "author_names": [ "M Carmen Ortega-Liebana", "Nguyen Xuan Chung", "Rens Limpens", "Leyre Gomez", "Jose L Hueso", "Jesus Santamaria", "Tom Gregorkiewicz" ], "corpus_id": 100127286, "doc_id": "100127286", "n_citations": 55, "n_key_citations": 1, "score": 0, "title": "Uniform luminescent carbon nanodots prepared by rapid pyrolysis of organic precursors confined within nanoporous templating structures", "venue": "", "year": 2017 }, { "abstract": "Carbon nanodots (CNDs)@BaSO4 hybrid phosphors are fabricated in an easy and low cost process by sequentially assembling Ba2+ and SO42 ions onto the surface of carbon nanodots through electrostatic attraction. CNDs act as the nucleus to attract these reactive ions and provide the luminescent centers in the hybrid phosphors. This strategy is versatile for a variety of negatively charged CNDs with different emission colors. The advantage of the resultant hybrid phosphors is that their luminescence exhibits excellent thermal and photostability, as well as remarkable resistance to strong acid/alkali and common organic solvents. These merits allow for the fabrication of CNDs based light emitting diodes using the CNDs@BaSO4 hybrid phosphors as a color conversion layer.", "author_names": [ "Ding Zhou", "Yuechen Zhai", "Songnan Qu", "Di Li", "Pengtao Jing", "Wenyu Ji", "De-Zhen Shen", "Andrey L Rogach" ], "corpus_id": 206500647, "doc_id": "206500647", "n_citations": 79, "n_key_citations": 0, "score": 0, "title": "Electrostatic Assembly Guided Synthesis of Highly Luminescent Carbon Nanodots@BaSO4 Hybrid Phosphors with Improved Stability.", "venue": "Small", "year": 2017 }, { "abstract": "Abstract Synthesized carbon dots (C dots) from Dioscorea hispida (Gadong tuber) starch were modified with passivating agents such as O O bis(3 aminopropyl)polyethylene glycol 1500 (PEG 1500N and branched polyethyleneimine (BPEI) to increase the functional efficiency of C dots to be used in biological investigations. After surface modification, the C dots decreased in size from 6 25 to 3 20 nm without changing their morphology. The modified C dots were fluorescent, and the fluorescence peak gradually shifted to a longer excitation wavelength (from 420 to 500) Upon modification, thereby elucidating a competitive quantum yield of 15% (C dots PEG 1500N and 12.6% (C dots BPEI) The UV visible spectrum of the C dots modified with PEG 1500N contained an absorption peak at 290 nm, whereas, that of the C dots modified with BPEI contained peak at 360. Fourier transform infrared analysis showed a peak at 1700 cm 1 (C dots PEG 1500N and 1697 cm 1 (C dots BPEI) that corresponds to the amide HCONH carbonyl bond, indicating that PEG 1500N and BPEI had been successfully passivated on the surface of C dots. To examine photothermal response, irradiation was carried out for 5 min using three different instruments which is UV lamp (365 nm) visible lamp and laser (532 nm, 1 W/cm 2 where temperature for each sample increased respectively. C dots demonstrated not losing their luminescent properties upon irradiation to UV lamp and laser for 30 min. Contrary, the intensity of fluorescence reduced when it exposed to the visible lamp for the same period. In vitro studies of the modified C dots with zebrafish Danio rerio revealed that C dots PEG 1500N is non toxic while C dots BPEI is highly toxic to the fish embryos. Significantly, this study has successfully demonstrated that Gadong tuber starch can be used as a starch based modifier for C dots; which possibly can be utilized as a nanocarrier with thermal sensing properties.", "author_names": [ "Regina Sisika A Sonthanasamy", "Shazrul Fazry", "Bohari Mohd Yamin", "Azwan Mat Lazim" ], "corpus_id": 125164980, "doc_id": "125164980", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Surface functionalization of highly luminescent carbon nanodots from Dioscorea hispida with polyethylene glycol and branched polyethyleneimine and their in vitro study", "venue": "Journal of King Saud University Science", "year": 2019 } ]

[ { "abstract": "When a tin whisker bridges two differently biased conductors, an electrical short is not guaranteed. In many instances, the voltage must exceed a threshold level in order to produce current flow due to weak physical contact and the presence of a non conductive film such as an oxide layer. This paper presents a study that examines the breakdown voltage of tin whiskers and its relation to contact force. Whisker contact force studies were conducted using gold and tin coated tungsten probes, and the breakdown voltage was measured using a semiconductor parameter analyzer. It was verified that contact force is a critical factor in determining the type of current voltage transition and level of breakdown voltage. Lower contact force between the probe and the whiskers caused the multiple transitions in current voltage characteristics. The tin oxide layers on whiskers were analyzed using field emission transmission electron microscopy (FE TEM)", "author_names": [ "Sungwon Han", "Michael D Osterman", "Michael G Pecht" ], "corpus_id": 6370584, "doc_id": "6370584", "n_citations": 8, "n_key_citations": 0, "score": 1, "title": "Electrical Shorting Propensity of Tin Whiskers", "venue": "IEEE Transactions on Electronics Packaging Manufacturing", "year": 2010 }, { "abstract": "Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. Also, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross sectioned and studied using a focused ion beam (FIB) The rare polycrystalline structure seen in the FIB cross section was confirmed using transmission electron microscopy (TEM) The FIB was also used to cross section two card guides to facilitate the measurement of the grain size to determine that the tin plating on the card guides had a bright finish.", "author_names": [ "Karim J Courey" ], "corpus_id": 107072598, "doc_id": "107072598", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "An Investigation of the Electrical Short Circuit Characteristics of Tin Whiskers", "venue": "", "year": 2013 }, { "abstract": "The Third Annual International Symposium on Tin Whiskers was held on 23 24 June 2009 at the Technical University of Denmark, Lyngby, Copenhagen, Denmark. The event contained two presentations that included non tin growths and zinc whisker formation being investigated by the author. The propensity for electroplated tin fi nishes to produce, among other morphologies, fi lamentous growths, thereby producing the very real danger of short circuiting in microelectronics, is a very real threat. The move by the European Union (EU) to ban lead (the only real mitigating agent for tin whiskers) through the well known RoHS and WEEE initiatives has made the reappearance of tin whiskers a real possibility. One organisation that is actively disseminating knowledge through annual symposia is the Centre for Advanced Life Cycle Engineering (CALCE) at the University of Maryland in the USA. Previous symposia have been held at the university in 2007 and in Japan in 2008. This year's symposium moved to Europe and was also co organised by the US Surface Mount Technology Association (SMTA) and the Technical University of Denmark (DTU) The writer had presented at the fi rst symposium, which was an excellent meeting, and was keen to attend and present at this third symposium. Michael Osterman (CALCE) welcomed delegates to the meeting and began by outlining the format of CALCE, its raison d'etre and its previous studies on the phenomenon of tin whiskers. He then handed over to Rajan Ambat, who is the Director of the Centre for Electronic Corrosion (CELCORR) at DTU. He welcomed delegates and explained a little more about the university and his centre which researches corrosion phenomena in electronic devices. The fi rst presentation was given by Katsuaki Suganuma of Osaka University. He outlined the research fi ndings on whiskers made by the Japanese Electronics and Information Technology Industries Association (JEITA) He presented data on whisker growth on a number of electroplated tin alloys including Sn Bi, Sn Ag and Sn Cu. The second presentation of the morning was by Barrie Dunn of the European Space Agency (ESA) Non tin whisker growths were discussed as were historical examples of more conventional tin whisker problems that had been highlighted by the ESA. More detailed examples were highlighted from 1995. The third presentation of the morning was given by Norio Nemoto of the Japanese Aerospace Exploration Agency (JAXA) Many Japanese parts manufacturers have shifted to lead free products although the equivalent Japanese directive to RoHS, JIS C 0950 (J MOSS) does not prohibit the use of lead only that its usage is indicated. JAXA have carried out much research into the effects of combined temperature cycling in vacuo on tin whisker growth. High vacuum levels promoted whisker growths of a similar length to those from surfaces cycled in a normal air atmosphere up to 500 times. Whiskers were longer and thinner in a vacuum after 1500 cycles. Tadahiro Shibutani from Yokohama National University in Japan examined the effect of grain size on pressure induced tin whisker formation. Three surface fi nishes were examined (SnCu, bright and matte tin) along with their propensity to form whiskers following nanoindentation. The threshold stress to form a whisker depended on the whisker diameter which in turn depended on the grain size of the tin based fi nish. Also from Japan, Minoru Ueshima from Senju Metal Industry Co. Ltd, examined the infl uence of fl ux type on whisker growth at a solder fi llet. Dimethyl amine HBr salt appeared to be associated with the most prevalent whisker growth and coincidentally the most marked corrosion. It was suggested that the two were interrelated. After lunch, Carol Handwerker from Purdue University in the USA examined tin whisker and surface defect formation on electroplated fi lms and refl owed joints. It was emphasised that stress was a driving force for tin whisker growth, but not a mechanism. The different whisker/defect morphologies were also discussed, along with other whisker formation driving forces including oxidation and corrosion and the occurrence of whisker growth on lead free solders (Sn Ag Cu) containing rare earth additions. Following Professor Handwerker was a presentation by Matthias Sobiech of Max Planck Institute for Metals Research (Stuttgart, Germany) and Robert Bosch GmbH (Stuttgart, Germany) His presentation described investigations into the driving force for whisker formation on Sn thin fi lms deposited on Cu. A conclusion was that the presence of compressive macrostresses in the Sn layer on its own is not a suffi cient condition for tin whisker growth. The stress distribution in the coating is more important. A negative out of plane stress gradient near the coating surface and a negative in plane stress gradient around the whisker root were said to be driving forces. Nils Arendt of Cookson Electronics gave the next presentation about a whisker reducing immersion tin technology with an 'organic nanometal' The organic metal (Ormecon, Ammersbek, Germany) is a conductive polymer behaving as a noble metal electrochemically with nanosized primary particles and catalytic properties. In its most effective whisker reducing form, it also contains Ag. With immersion tin coating processes, it is used as a predip before tin deposition and has been found to lessen subsequent tin whisker formation. The running theme of stress and tin whisker growth was continued by Maureen Williams of National Institute of Standards and Technology (Gaithersburg, MD, USA) Simultaneous and time resolved measurements of stress in Sn and SnCu electrodeposits were made using cantilever defl ection and X ray diffraction techniques. SnCu coatings had a more compressive stress than pure Sn and produced more whiskers, eruptions and hillocks. The defl ection and X ray diffraction techniques showed different results and it was unclear, which was a better engineering predictor of whiskering. Geoff Wilcox (Loughborough University) made the penultimate presentation of the day looking at zinc whisker growth from electrodeposited coatings. Zinc whiskers are often", "author_names": [ "Geoffrey D Wilcox" ], "corpus_id": 218667519, "doc_id": "218667519", "n_citations": 81, "n_key_citations": 3, "score": 0, "title": "Whiskers", "venue": "", "year": 2010 }, { "abstract": "Introduction 1 Risks Related To Tin Whiskers 2 A Brief Description Of Tin Whiskers 2 Tin Whisker Growth Mechanism 2 Mitigation Strategies 3 Avoid Tin Plated Parts 4 Strip and Replate 5 Solder Dip the Plated Surfaces Sufficiently Using a Tin Lead Solder 5 Select a Matte or Low Stress Tin Finish 6 Select Underplating (Barrier layer) to Reduce Intermetallic Formation 6 Vary Thickness of Tin Plating 6 Annealing 7 Avoid Applying Compressive Loads on Plated Surfaces 8 Apply a Conformal Coat 8 Evaluate Application Specific Risks 10 Summary and Conclusions 10 References 10 Document Development Details 11", "author_names": [ "M Osterman Calce-Epsc" ], "corpus_id": 17939682, "doc_id": "17939682", "n_citations": 31, "n_key_citations": 1, "score": 0, "title": "Mitigation Strategies for Tin Whiskers", "venue": "", "year": 2002 }, { "abstract": "Spectacular damage of several relays from high current flowing to the metal case was very likely caused in each instance by a tin whisker growing from the armature, which is bright tin plated, toward a terminal stud. This plating is a nonconformance to the applicable military specification that was in effect at the time of manufacture. The other possible causes, wearout (arcing deposits creating a conductive path between phases) and particles are considered and shown to be unlikely.", "author_names": [ "Gordon Davy" ], "corpus_id": 167214699, "doc_id": "167214699", "n_citations": 8, "n_key_citations": 1, "score": 0, "title": "Relay Failure Caused by Tin Whiskers", "venue": "", "year": 2003 }, { "abstract": "The movement to eliminate lead (Pb) especially active in Japan and the European Union, has resulted in an increasing use of pure tin (Sn) coatings on leads and other external and internal surfaces of capacitors, resistors, and other passive components. This paper discusses the issues of tin whisker growth with respect to passive components. It also presents both a critical analysis of existing published documents on tin whisker nucleation and growth and a summary of very recent experiments that provide further understanding of the potential means of whisker formation mitigation. Many of the proposed mechanisms for mitigation, including control of the immediate underplating material, use of conformal coating, regulating the thickness of the tin coating, use of matte tin electroplating, and annealing or fusing of the tin layer, are inadequate. They likely reduce the incidence of nucleation or growth but do not provide an absolute guarantee of lack of whisker formation.", "author_names": [ "Jay Brusse", "Gary J Ewell", "Jocelyn Siplon" ], "corpus_id": 36779394, "doc_id": "36779394", "n_citations": 71, "n_key_citations": 2, "score": 0, "title": "TIN WHISKERS: ATTRIBUTES AND MITIGATION", "venue": "", "year": 2002 }, { "abstract": "The connector industry is at a crossroads with respect to selecting lead free coatings in response to legislation and customer demands. Component manufacturers have long used tin lead coatings because of lead's ability to inhibit tin whisker formation. Several lead free alternate finishes such as pure tin, tin bismuth, tin copper, tin zinc, Pd, and Pd Ni Au have been proposed. One simple, economical, and easy drop in replacement is pure matte tin. Unfortunately, pure tin films have a fairly high risk of whisker formation. Factors, such as substrate material, plating process variables, and assembly operations also play a role in whisker generation. The stresses imposed at each process step pose a serious threat to whiskering. We have critically evaluated three matte tin chemistries by changing bath composition and deposition parameters. We also characterized stresses in these matte tin coatings by using flexure beam and X ray diffraction techniques. This paper identifies stress types encountered in various connector applications, provides an insight to the users about practical situations, and suggests whisker mitigation strategies. The impact of environmental (e.g. temperature and humidity) stresses on tin coatings is also discussed.", "author_names": [ "Sudarshan Lal", "Thomas D Moyer" ], "corpus_id": 35564040, "doc_id": "35564040", "n_citations": 44, "n_key_citations": 2, "score": 0, "title": "Role of intrinsic stresses in the phenomena of tin whiskers in electrical connectors", "venue": "IEEE Transactions on Electronics Packaging Manufacturing", "year": 2005 }, { "abstract": "Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance, electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data, we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. In addition, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross sectioned and studied using a focused ion beam (FIB)", "author_names": [ "Karim J Courey", "Shihab S Asfour", "Jon A Bayliss", "Larry L Ludwig", "M C Zapata" ], "corpus_id": 19071176, "doc_id": "19071176", "n_citations": 10, "n_key_citations": 1, "score": 0, "title": "Tin Whisker Electrical Short Circuit Characteristics Part I", "venue": "IEEE Transactions on Electronics Packaging Manufacturing", "year": 2008 }, { "abstract": "To comply with lead free legislation, many manufacturers have converted from tin lead to pure tin finishes of electronic components. However, pure tin finishes have a greater propensity to grow tin whiskers than tin lead finishes. Since tin whiskers present an electrical short circuit hazard in electronic components, simulations have been developed to quantify the risk of said short circuits occurring. Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that had an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM) The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish", "author_names": [ "Karim J Courey", "Shihab S Asfour", "Arzu Onar", "Jon A Bayliss", "Larry L Ludwig", "Maria C Wright" ], "corpus_id": 106818715, "doc_id": "106818715", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Estimating the Probability of Electrical Short Circuits from Tin Whiskers", "venue": "", "year": 2013 }, { "abstract": "A technique using interdigitated, specially electroplated discs has been developed at the National Physical Laboratory for determining the relative ability of conformal coatings to mitigate against Sn whisker growth. All the control samples without conformal coatings developed whiskers of sufficient length >250mm) to cause electrical shorts between the discs. The electrical monitoring system was able to detect these shorts and the current flowing in the detection circuit was restricted to a level sufficient to prevent destruction of the whiskers. The control samples all exhibited electrical shorts within 14 days, some within as few as 3 days, allowing for a relatively rapid i.e. less than 12 week evaluation of the Sn whisker mitigation benefits of conformal coatings.", "author_names": [ "Martin Wickham", "Christopher Hunt" ], "corpus_id": 181882131, "doc_id": "181882131", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Test method for measurement of the propensity for conformal coatings to inhibit tin whiskering.", "venue": "", "year": 2008 } ]

[ { "abstract": "Mesoporous ceramics and semiconductors enable low cost solar power, solar fuel, (photo)catalyst and electrical energy storage technologies. State of the art, printable high surface area electrodes are fabricated from thermally sintered pre formed nanocrystals. Mesoporosity provides the desired highly accessible surfaces but many applications also demand long range electronic connectivity and structural coherence. A mesoporous single crystal (MSC) semiconductor can meet both criteria. Here we demonstrate a general synthetic method of growing semiconductor MSCs of anatase TiO2 based on seeded nucleation and growth inside a mesoporous template immersed in a dilute reaction solution. We show that both isolated MSCs and ensembles incorporated into films have substantially higher conductivities and electron mobilities than does nanocrystalline TiO2. Conventional nanocrystals, unlike MSCs, require in film thermal sintering to reinforce electronic contact between particles, thus increasing fabrication cost, limiting the use of flexible substrates and precluding, for instance, multijunction solar cell processing. Using MSC films processed entirely below 150 degC, we have fabricated all solid state, low temperature sensitized solar cells that have 7.3 per cent efficiency, the highest efficiency yet reported. These high surface area anatase single crystals will find application in many different technologies, and this generic synthetic strategy extends the possibility of mesoporous single crystal growth to a range of functional ceramics and semiconductors.", "author_names": [ "Edward J W Crossland", "Nakita K Noel", "Varun Sivaram", "T Leijtens", "Jack A Alexander-Webber", "Henry J Snaith" ], "corpus_id": 4431825, "doc_id": "4431825", "n_citations": 653, "n_key_citations": 2, "score": 1, "title": "Mesoporous TiO2 single crystals delivering enhanced mobility and optoelectronic device performance", "venue": "Nature", "year": 2013 }, { "abstract": "DOI: 10.1002/ppsc.201800198 past few years for their high aspect ratio (surface to volume ratio) distinctive physicochemical properties compared to the conventional nanostructures. Under equilibrium, {001} facet dominated TiO2 nanostructure is rarely observed as it has very high surface energy (average surface energy of {001} facet (0.90 J m 2) is double that of {101} facet (0.44 J m 2)[14] Thus, during the usual growth process, the less reactive {101} facet is dominated over the highly reactive {001} facet. However, several reports[14 16] have been published on the controlled growth of TiO2 single crystals with exposed {001} facet after the breakthrough work by Yang et al.[17] that demonstrated the hydrothermal synthesis of anatase TiO2 single crystals with 47% exposed {001} facet. Following this work, {001} facet dominated TiO2 microcrystals are being extensively investigated with various doping and photocatalytic applications for environmental cleaning. Recently, mesoporous TiO2 single crystals delivering enhanced mobility and optoelectronic device performance was reported by Crossland et al.[18] Ding et al. reported on mesoporous hollow TiO2 microspheres with enhanced photoluminescence (PL)[19] However, most of these works were carried out using a mesoporous template method and the PL yield was not addressed in these works. To the best of our knowledge, there is no report on fluorine doping of mesoporous TiO2 nanostructure and the extremely high PL quantum yield (QY) of self grown anatase fluorine doped TiO2 (F TiO2) nanocrystals (NCs) on mesoporous F TiO2 flowers. Thus, a detailed study on structural and optical properties of mesoporous F TiO2 nanostructures is warranted to explore its novel properties including high PL QY. With conventional semiconductor quantum dots, chiral quantum dots based cellular imaging, sensing, and biomedical applications are not so encouraging because of the involvement of toxic elements such as cadmium[20] in the chiral composition. This hinders its applicability in living cells and study for nontoxic analogues of these chiral luminescent nanomaterials is of great interest.[21] Recently, Cleary et al.[22] reported on the highly luminescent TiO2 nanoparticles (NPs) with chiral capping ligand having size 30 50 nm with a PL QY up to 3.5% However, the reported PL yields were measured mostly in colloidal solution, where surface functionalization by the solvents Herein a novel approach is reported to achieve tunable and high photoluminescence (PL) quantum yield (QY) from the self grown spherical TiO2 quantum dots (QDs) on fluorine doped TiO2 (F TiO2) flowers, mesoporous in nature, synthesized by a simple solvothermal process. The strong PL emission from F TiO2 QDs centered at 485 nm is associated with shallow and deep traps, and a record high PL QY of 5.76% is measured at room temperature. Size distribution and doping of F TiO2 nanocrystals (NCs) are successfully tuned by simply varying the hf.rst.imncentration during synthesis. During the post growth rapid thermal annealing (RTA) under vacuum, the arbitrary shaped F TiO2 NCs transform into spherical QDs with smaller sizes and it shows dramatic enhancement (163 times) in the PL intensity. Electron spin resonance (ESR) and X ray photoelectron spectroscopy (XPS) confirm the high density of oxygen vacancy defects on the surface of TiO2 NCs. Confocal fluorescence microscopy imaging shows bright whitish emission from the F TiO2 QDs. Low temperature and time resolved PL studies reveal that the ultrafast radiative recombination in the TiO2 QDs results in highly efficient PL emission. A highly stable, biologically inert, and highly fluorescent TiO2 QDs/flowers without any capping agent demonstrated here is significant for emerging applications in bioimaging, energy, and environmental cleaning. Quantum Dot Photoluminescence", "author_names": [ "Kamal Kumar Paul", "Subhadip Jana", "P K Giri" ], "corpus_id": 53571320, "doc_id": "53571320", "n_citations": 11, "n_key_citations": 0, "score": 0, "title": "Tunable and High Photoluminescence Quantum Yield from Self Decorated TiO2 Quantum Dots on Fluorine Doped Mesoporous TiO2 Flowers by Rapid Thermal Annealing", "venue": "", "year": 2018 }, { "abstract": "Abstract A rational solvothermal method is proposed to achieve the conversion from a Zn contented metal organic framework to ZnO mesoporous single crystal like spheres. The as prepared ZnO sphere is composed of oriented assembled primary crystals, which exhibits single crystal nature with narrow pore size distribution and high surface area. In addition, time depending trails indicate the metal organic framework functions as reservoir to control the release of Zn species and the organic molecules also serve as directing regent to facilitate the oriented assembling of the ZnO primary units. Thanks to this structure coherence, the ZnO sphere delivers high electron mobility, which enables reduced carrier recombination and improved collection efficiency of the photoelectrons when used as photoanode in CdS/CdSe sensitized solar cell. The device achieves a high power conversion efficiency of ~6.20% which is substantially improved from that of regular ZnO nanoparticles ~5.02% Moreover, when evaluated as anode for lithium ion battery, the ZnO sphere based electrode demonstrates high reversible capacity of 1016.7 mA h g 1 at 100 mA g 1 after 100 cycles, and excellent high rate stability which shows impressive reversible capacity of 698.4 mA h g 1 at 1000 mA g 1 after 300 cycles.", "author_names": [ "Dapeng Wu", "Yixin Wang", "Nana Ma", "Wenchao Zhang", "Danqi Wang", "Zhiyong Gao", "Fang Xu", "Kai Jiang" ], "corpus_id": 107489486, "doc_id": "107489486", "n_citations": 17, "n_key_citations": 0, "score": 0, "title": "Single crystal like ZnO mesoporous spheres derived from metal organic framework delivering high electron mobility for enhanced energy conversion and storage performances", "venue": "Electrochimica Acta", "year": 2019 }, { "abstract": "A facile low temperature synthetic method of growing semiconductor mesoporous single crystal of anatase TiO2 directly on FTO substrate was developed. The templated hydrothermal synthesis approach was employed to make mesoporous single crystal TiO2 that contains pores tens to hundreds of nanometres in size under low temperature, which opens a potential way to produce useful functional thin film photoanodes by one pot approach for fabricating cheap and highly efficient optoelectronic devices. This method is based on seeded nucleation and growth inside a pre formed mesoporous silica film template immersed in diluted precursor solution. The electrochemical characterizations showed that the directly grown mesoporous single crystal thin film on FTO substrate has substantially higher conductivity and electron mobility than conventionally deposited TiO2 thin films by printing techniques. Hence, using the as synthesized mesoporous single crystal thin film baking at 150 degrees C as photoanodes, an encouraging 5.83% solar to electricity conversion efficiency was achieved. It is expected that the developed mesoporous single crystals on FTO substrate may find broader applications in many different technologies. This generic synthetic strategy extends the possibility of mesoporous single crystal films directly growing to a range of substrates. Moreover, this approach could work at lower temperatures below 150 degrees C, which could considerably minimize the environmental impact and production costs of high performance mesoporous materials. (C) 2015 Elsevier Ltd. All rights reserved.", "author_names": [ "Hua Yu", "Lianzhou Wang", "Matthew Simon Dargusch" ], "corpus_id": 97774296, "doc_id": "97774296", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Low temperature templated synthesis of porous TiO2 single crystals for solar cell applications", "venue": "", "year": 2016 }, { "abstract": "Single crystalline perovskite solar cells (PSC) are promising for their inherent stability due to the absence of grain boundaries. While the development of single crystals of perovskite with enhanced optoelectronic properties is known, studies on the growth, device performance and understanding of the intrinsic stability of single crystalline perovskite thin film solar cell devices fabricated on electron selective contacts are scarcely explored. In this work, we examine the impact of mesoporous TiO2 (m TiO2) and planar TiO2 (p TiO2) on the growth of single crystalline methyl ammonium lead iodide (SC MAPbI3) film, PSC device performance and film stability under harsh weather conditions (T 85 degC and RH 85% Self grown SC MAPbI3 films are developed on m TiO2 and p TiO2 by inverse temperature crystallization under ambient conditions without the need for sophisticated glove box processing. The best device with m TiO2 as an electron transport layer showed a promising power conversion efficiency of 3.2% on an active area of 0.3 cm2 in hole transport material free configuration, whereas, only 0.7% was achieved for the films developed on p TiO2. Complete conversion of precursor to perovskite phase and better surface coverage of the film leading to enhanced absorption and reduced defects of single crystalline perovskite on m TiO2 compared to its p TiO2 leads to this large difference in efficiency. Mesoporous device retained more than 70% of its initial performance when stored at 30 degC under dark for more than 5000 h at 50% RH; while the planar device degraded after 1500 h. Thermal and moisture endurance of SC MAPbI3 films are investigated by subjecting them to temperatures ranging from 35 degC to 85 degC at a constant relative humidity (RH) of 85% X ray diffraction studies show that the SC MAPbI3 films are stable even at 85 degC and 85% RH, with only slight detection (30 35% of PbI2 at these conditions. This study highlights the superior stability of SC MAPbI3 films which paves way for further studies on improving the stability and performance of the ambient processed PSCs.", "author_names": [ "Ramya Krishna Battula", "Ganapathy Veerappan", "Puttaiah Bhyrappa", "C Sudakar", "Easwaramoorthi Ramasamy" ], "corpus_id": 225434159, "doc_id": "225434159", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "Stability of MAPbI3 perovskite grown on planar and mesoporous electron selective contact by inverse temperature crystallization", "venue": "", "year": 2020 }, { "abstract": "Organic inorganic hybrid perovskite solar cells (PSCs) employing a mesoporous metal oxide scaffold are now at the forefront of solution processed photovoltaic cells, yielding a power conversion efficiency exceeding 23% However, processing temperatures of up to 450 degC are typically required to sinter mesoporous metal oxide scaffolds, which hinders the fabrication of low cost and flexible devices. Moreover, these metal oxide scaffolds usually suffer from high charge carrier recombination rates and inherent UV instability. In this paper, we develop for the first time an organic scaffold architecture, which consists of room temperature processed C60 single crystalline nanoparticles (C60 NPs) serving as an electron selective contact covering on C60 compact films (c C60) C60 NPs act as a three dimensional framework to support perovskite crystals, enabling them to cover the substrate more uniformly and thus demonstrating an advantage over planar heterojunction PSCs. Furthermore, the higher electron mobility of C60 NPs compared with commonly used TiO2 enhances the charge transfer from the perovskite to electron transport layers and reduces charge carrier accumulation at the interface, demonstrating the advantage of an organic scaffold over inorganic metal oxides for mesoporous scaffold PSCs. A power conversion efficiency (PCE) of 19.45% was obtained in organic scaffold MAPbI3 based perovskite solar cells (OPSCs) outperforming standard reference devices based on a TiO2 mesoporous scaffold (maximum PCE 17.07% Furthermore, the high UV stability of C60 NPs enables the realisation of ultra stable OPSCs stressed under ambient conditions and working under both UV and full sun illumination. Moreover, the devices can be easily processed at low temperatures, providing an efficient method for the large scale production of flexible PSCs. These flexible PSCs show remarkable performance with an excellent PCE of 17.28% which is among the highest values reported for MAPbI3 based flexible PSCs to date. This work reveals that organic nanostructures as n type charge collection layers are ideal replacements for inorganic mesoporous scaffolds as they achieve remarkably high efficiency and long term operational stability in both rigid and flexible perovskite solar cells.", "author_names": [ "Xiaoming Zhao", "Lixian Tian", "Tianjun Liu", "Hongli Liu", "Shirong Wang", "Xianggao Li", "Oliver Fenwick", "Shengbin Lei", "Wenping Hu" ], "corpus_id": 104398280, "doc_id": "104398280", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Room temperature processed fullerene single crystalline nanoparticles for high performance flexible perovskite photovoltaics", "venue": "", "year": 2019 }, { "abstract": "Abstract Morphological and crystalline control over hybrid organic inorganic perovskite films is pivotal for efficient photovoltaic (PV) performance devices. Yet, this remains very challenging for solution processed perovskite solar cells (PVSCs) especially mesoscopic PVSCs, due to the complicated crystallization kinetics of hybrid semiconductor materials within dynamic spin coating and post annealing. In this work, colloidal Ge nanoparticles (NPs) were added onto a mesoporous TiO2 (m TiO2) electron transporting layer (ETL) to regulate perovskite crystal growth. Systematic investigation and optimization disclose that incorporation of an appropriate ratio of Ge NPs onto the m TiO2 ETL can simultaneously increase the size of the CH3NH3PbI3 crystals, decrease the number of the grain boundaries and promote the interfacial properties of perovskite/m TiO2. The related mechanisms are clarified through detailed morphology and crystal structure analyses. The electron mobility of the perovskite absorber, determined using the space charge limited current (SCLC) method, was increased by over 5 times when an optimized amount of Ge NPs were employed. Average power conversion efficiency (PCE) of 18.59% was achieved from 16 cells and the best PCE of 19.6% was attained via the addition of the optimized amount of Ge NPs. We study the fundamentals of optics and physics behind the PVSC device based on the high refractive index Ge NPs. This work offers an innovative scenario to enhance the performance of perovskite based optoelectronics by employing optically stable, chemically inert, low cost and green semiconductor NPs.", "author_names": [ "Chenxi Zhang", "Zaifeng Li", "Xueshuang Deng", "Bing Yan", "Zengbo Wang", "Xiaohong Chen", "Zhuo Sun", "Sumei Huang" ], "corpus_id": 198453298, "doc_id": "198453298", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Enhancing photovoltaic performance of perovskite solar cells utilizing germanium nanoparticles", "venue": "Solar Energy", "year": 2019 }, { "abstract": "From the last few decades, organic semiconductors based electronic and optoelectronic devices have been the area of intense research.Organic semiconductors have gained remarkable importance in electronic and optoelectronic industry due to conjugated structure, low cost production, mechanical flexibility, ease of device fabrication and environmental friendly processing.In the research work reported in this dissertation, electronic, optoelectronic and amplified spontaneous emission (ASE) studies are carried out on (i) junction diodes using n type organic semiconductors, (ii) sensors fabricated using organic semiconductors and organic inorganic nanocomposites, and (iii) newly synthesized single crystal oligothiophene, respectively.The organic n type semiconductors N Butyl N' (6 hydroxy hexyl) perylene 3,4,9,10 tetracarboxylic acid diimide (N BuHHPDI) and perylene 3,4,9,10 tetra carboxylic acid di anhydride (PTCDA) have been synthesized and employed for their potential applications in organic devices such as Schottky barrier junction (SBJ) heterojunction (HJ) and organic multifunctional sensors.The fabricated rectifying junctions, i.e. Schottky junction and heterojunction, are characterized by conventional current voltage (I V) method at ambient atmospheric condition at in dark. Different junction factors i.e. turn on voltage (Vt) ideality factor/quality factor (n) rectification ratio (RR) barrier height (phb) reverse saturation current (I0) series resistance and shunt resistance are determined from the I V curves. Other two well known characterization techniques, Norde's technique and Cheungs' functions, are applied to measure the aforementioned parameters of the diode.The parameters extracted by these different characterization methods are compared and found in good agreement with each other.To understand the temperature dependence of the heterojunction device parameters, the I V properties of the heterojunction are studied at various temperatures from 300 K to 330 K.This has been observed that with the increase in temperature the ideality factor, turn on voltage and series resistance of the junction are significantly decreased. While the reverse saturation current and rectification ratios are increased.The morphological study of the thin films of N BuHHPDI and PTCDA deposited on quartz glass has been carried out by scanning electron microscope (SEM) and atomic force microscope (AFM) Size of the grain, shape, orientation and average surface roughness of the thermally deposited films has been measured from the microscopy.Energy dispersive spectroscopy (EDX) has been done for these samples to confirm the composition of these newly synthesized organic materials.To measure the optical band gap of these materials, ultra violet and visible (UV Vis) spectroscopy has been performed. The N BuHHPDI is insoluble in water and possesses excellent hydrophobic properties.This hydrophobic property makes these materials more distinctive candidates for humidity sensing applications as compared to other water soluble organic materials.The high sublimation temperature (700 K) is another convincing characteristic of this class of materials for their potential application as a temperature sensor to monitor temperature at elevated levels.At the same time, the broad UV Vis spectrum and good absorption of light recommend perylenes equally useful for light sensing applications.Thus, taking advantages of these motivating properties, the potential of perylene has been explored for humidity, temperature and light sensing applications due to the possession of such interesting properties all together.To enhance the performance of the organic semiconductor based sensors, one way is to make the sensor at nanoscale and the other is to blend organic semiconductor with some functional nanoparticles/nanofibers.For this reason, an organic azo dye, methyl orange (MO) has been used as an active semiconducting matrix in which the TiO2 nanoparticles have been disapersed.The fabricated sensor response has been observed at different humidity andtemperature values. Fast recovery time and response time of the sensor has been achieved due to the introduction of TiO2 nanoparticles by taking advantage of large surface to volume ratio of the nanoparticles.Concerning photonic characteristics of organic polymers and small molecules, conjugated polymers based optically pumped lasers have been produced both from solution and thin films.However, significant hard work is being carried out on these conjugated molecules to enhance their carriers' mobility and to minimize the threshold energy required for lasing to develop electrically pumped polymer laser diodes. Such types of materials for lasers may ultimately compete with their inorganic counterparts in many ways such as inexpensive, low temperature and high throughput fabrication. One special type of these materials is single crystal oligomers which, in the last decade, have got incredible attention due to their interesting properties such as high charge carriers' mobility, chemically adjustable wavelengths, large photoluminescence quantum efficiency (PLQE) large stimulated emission cross sections and as a high optical gain media for their prospective uses in solid state lasers and broadband amplifiers.The amplified spontaneous emission (ASE) optical gain and PLQE properties of a newly synthesized single crystal oligothiophene 5, 5' diphenyl 2, 2':5' 2':5' 2':5' 2':5' 2' sexithiophene (P6T) are reported. This oligomer crystal has been grown on glass substrate in a dimension of 5mm x 2mm with 10 mm thickness, by Prof. Shu Hotta, Kyoto Institute of Technology, Japan and its photonic properties have been studied at Cavendish Lab, Cambridge, UK.", "author_names": [ "Muhammad Tahir" ], "corpus_id": 138206697, "doc_id": "138206697", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Fabrication And Study of Organic Electronic And Optoelectronic Devices", "venue": "", "year": 2014 }, { "abstract": "A low temperature synthesis has been developed to make single crystals of titanium dioxide that contain pores tens to hundreds of nanometres in size. This opens the way to cheap, highly efficient optoelectronic devices. See Letter p.215 Mesoporous semiconductors and ceramics have large surface areas that can be exploited in high performance solar cells, as photocatalysts and in batteries. This paper describes a low temperature (below 150 degC) general synthetic method of growing micrometre sized semiconductor mesoporous single crystals of a form of titanium dioxide (TiO2) known as anatase, based on seeded nucleation and growth inside a mesoporous template immersed in a dilute reaction solution. The authors demonstrate that both isolated crystals and ensembles incorporated into films exhibit dramatically higher conductivities and electron mobilities than nanocrystalline TiO2. Dye sensitized solar cells made from these materials demonstrate 7.3% efficiency, the highest value so far reported using low temperature processing. The synthesis method should be generally applicable to other functional ceramics and semiconductors.", "author_names": [ "Caterina Ducati" ], "corpus_id": 4313127, "doc_id": "4313127", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Materials science: Porosity in a single crystal", "venue": "Nature", "year": 2013 }, { "abstract": "AbstractOwing to the electron scattering at the surface, the grain boundaries, and the defects of titanium dioxide (TiO2) nanoparticles (NPs) the electron diffusion length in the mesoporous TiO2 layer is shorter than that of TiO2 bulk single crystal, leading to a significantly increased charge recombination in dye sensitized solar cells (DSSCs) herein TiO2 photoanode sandwiching a layer of high mobility indium tin oxide (ITO) granular film to form a TiO2/ITO/TiO2 (TIT) photoanode. A large number of ITO NPs would penetrate deep into the mesoporous TiO2 bottom layer to form the interconnected network, which can be served as high speed electron transport channels, thereby enhancing the electron transfer and collection abilities. Compared with the reference device assembled with TiO2/TiO2 (TT) photoanode, an increase of 14.78% in power conversion efficiency (PCE) was obtained for the optimized TIT device (8.23 vs 7.17% which can be ascribed to the synergistic effects of faster electron transport and less charge recombination. Moreover, the electron transfer ability of TIT layer was also superior to TiO2 ITO composite photoanode, in which ITO NPs were uniformly dispersed in the TiO2 mesoporous layer. Overall, this method paves a facile and effective way to improve the photovoltaic performance for highly efficient DSSCs of practical significance. Graphical abstractThe interconnected transport channel consisting of the high mobility ITO interlayer enhances the electron transfer and collection abilities.", "author_names": [ "Haijun Chen", "Tao Liu", "Bing Wang", "Zheting Liu", "Yingxiang Li", "Qiang Zhao", "Ning Wang", "Hongcai He", "Hu Liu", "Zhanhu Guo" ], "corpus_id": 103710126, "doc_id": "103710126", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "Highly efficient charge collection in dye sensitized solar cells based on nanocomposite photoanode filled with indium tin oxide interlayer", "venue": "Advanced Composites and Hybrid Materials", "year": 2018 } ]

[ { "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 In recent years, catalytic hydrolysis of sodium borohydride is considered to be a promising approach for hydrogen generation towards fuel cell devices, and highly efficient and noble metal free catalysts have attracted increasing attention. In our present work, Co3O4 nanocubes are synthesized by solvothermal method, and then vapor phase phosphorization treatment is carried out for the preparation of novel Co O P composite nanocatalysts composed of multiple active centers including Co, CoO, and Co2P. For catalyst characterization, field emission scanning electron microscopy (FE SEM) transmission electron microscopy (TEM) energy dispersive spectrometry (EDS) X ray diffraction (XRD) and X ray photoelectric spectroscopy (XPS) are conducted. Optimal conditions for catalyst preparation and application were investigated in detail. At room temperature (25 degC) maximum hydrogen generation rate (HGR) is measured to be 4.85 L min 1 g 1 using a 4 wt% NaBH4 8 wt% NaOH solution, which is much higher than that of conventional catalysts with single component reported in literature. It is found that HGR remarkably increases with the increasing of reaction temperature, and apparent activation energy for catalytic hydrolysis of NaBH4 is calculated to be 63 kJ mol 1. After reusing for five times, the Co O P composite nanocatalysts still retains 78% of the initial activity.", "author_names": [ "Lei Wei", "Xiaolong Dong", "Yumei Yang", "Qianqian Shi", "Yanhong Lu", "Hongyan Liu", "Ya-Na Yu", "Meng-Han Zhang", "Meng Qi", "Qin-qin Wang" ], "corpus_id": 213988135, "doc_id": "213988135", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Co O P composite nanocatalysts for hydrogen generation from the hydrolysis of alkaline sodium borohydride solution", "venue": "", "year": 2020 }, { "abstract": "Abstract In this work, we developed ternary metallic cobalt cobalt nitride dicobalt phosphide composite embedded in nitrogen and phosphorus co doped carbon (Co/CoN/Co2P NPC) as bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) The as prepared Co/CoN/Co2P NPC is achieved by simultaneous annealing and phosphating of a Co N rich metal organic frameworks (MOFs) precursor. Compare with the phosphorus free Co/CoN embedded nitrogen doped carbon electrocatalyst (Co/CoN NC) the as prepared Co/CoN/Co2P NPC display superior HER and OER low overpotential of 99 mV and 272 mV at current density of 10 mA cm 2. When Co/CoN/Co2P NPC electrocatalyst is use as bifunctional catalysts in overall alkaline water splitting, it exhibit excellent behaviour with 10 mA cm 2 current at overall cell potential of 1.60 V. The excellent performance of Co/CoN/Co2P NPC electrocatalyst is attributed to the phosphating process that could further enhance synergistic effect, create stronger electronic interactions, and form efficient dual heteroatom doping to optimize the interfacial adhesion within the electrocatalyst. This present work will create more opportunities for the development of new, promising and more active sites electrocatalysts for alkaline electrolysis.", "author_names": [ "Lei Hu", "Yu-wen Hu", "Ran Liu", "Yanchao Mao", "Muhammad-Sadeeq Balogun", "Yexiang Tong" ], "corpus_id": 145884266, "doc_id": "145884266", "n_citations": 53, "n_key_citations": 0, "score": 0, "title": "Co based MOF derived Co/CoN/Co2P ternary composite embedded in N and P doped carbon as bifunctional nanocatalysts for efficient overall water splitting", "venue": "International Journal of Hydrogen Energy", "year": 2019 }, { "abstract": "Direct alkaline ethanol fuel cells (DAEFCs) have attracted great attention as one of the most promising portable energy systems. In this work, we report a novel and facile method to prepare PdAg/xCeO2/C hybrid nanostructured anode catalysts without reducing agents or surfactants. The microstructure and morphology of the as synthesized nanocatalysts were investigated by X ray diffraction (XRD) high resolution transmission electron microscopy (HRTEM) and X ray photon spectroscopy (XPS) techniques. Furthermore, the electrochemical performance of the resultant catalysts was studied using cyclic voltammetry (CV) and chronoamperometry (CA) measurements. Among the different compositions of PdAg/xCeO2/C catalysts, PdAg/30CeO2/C showed the highest performance for ethanol electro oxidation reaction (EOR) in the alkaline medium. Such an excellent performance for the EOR indicates that the as synthesized PdAg/30CeO2/C catalyst could be potentially used as a high performance anode catalyst in DAEFCs.", "author_names": [ "Ayong Xie", "Qing Zhang", "Hui He", "Cheng Peng" ], "corpus_id": 224922596, "doc_id": "224922596", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Facile synthesis of PdAg nanocatalysts on CeO2/C composite supports as high performance catalysts toward alkaline ethanol electro oxidation", "venue": "", "year": 2020 }, { "abstract": "Abstract Graphene possesses many superior properties which make it an ideal matrix to support semiconductors. Recently, graphene/semiconductor composites have been applied increasingly in environmental remediation and energy production. This review provided a general overview of the latest research results of graphene/semiconductor composites nanocatalysts. Firstly, synthetic methods of graphene/semiconductor composites were summarized. The roles of graphene in promoting semiconductor photocatalytic performance including increasing the adsorption of reactants, expanding the range of light absorption and intensity, acting as a photosensitizer and electron transfer medium were then emphasized. Next, the performance and mechanisms in pollutants removal, disinfection, hydrogen evolution, CO2 reduction, selective oxidation, nitroaromatics reduction, sensing, supercapacitors and other fields were presented. Besides, the toxicity of graphene and graphene/semiconductor composites was also introduced to help understand the impact on living systems of the environment. Finally, perspectives and challenges of graphene/semiconductor composites for future development were proposed. This review gives a comprehensive and updated overview of graphene/semiconductor composites for environmental and energy applications and is expected to shed light on the further study in this exciting area.", "author_names": [ "Yu-Mei Hu", "Chengyun Zhou", "Han Wang", "Ming Chen", "Guangming Zeng", "Zhifeng Liu", "Wenjun Wang", "Ting Wu", "Binbin Shao", "Qinghua Liang" ], "corpus_id": 233553120, "doc_id": "233553120", "n_citations": 3, "n_key_citations": 0, "score": 1, "title": "Recent advance of graphene/semiconductor composite nanocatalysts: Synthesis, mechanism, applications and perspectives", "venue": "", "year": 2021 }, { "abstract": "Direct alcohol fuel cells (DAFCs) are widely regarded as one of the most promising among the futuristic and capable energy systems; direct liquid fuel cells (DLFCs) In this article, we discuss in detail the competency of palladium nanoparticles developed over carbon ceria composite supports (Pd/C CeO2) as efficient and durable anode catalysts for the alkaline electro oxidation of ethylene glycol (EGOR) For the first time, a systematic assessment of the EGOR performance of palladium catalysts with varying Pd ceria ratios has been reported. The scalable solid solution route reduction technique enabled the processing of Pd nanoparticles with controlled morphology, size and excellent CeO2 interaction. The structural features of the prepared catalysts were studied using X ray diffraction, electron microscopy (TEM) and X ray photon spectroscopy techniques, while the electrochemical performance of the catalysts was analyzed using cyclic voltammetry and chronoamperometry. During alkaline EGOR, the Pd/C CeO2 catalysts showed an enhanced current density (as high as 68.5 mA cm 2) more negative onset potential, excellent mass activity (4.6 A mg 1Pd) and exceptional durability compared to Pd/C. The enhanced alkaline EGOR kinetics of the Pd/C CeO2 catalysts is well attributed to the promotion effect of CeO2 on Pd by creating more Pd OHads and also improved tolerance to poisoning species on the Pd surface. Further, the enhanced ECSA of Pd/C CeO2 has also aided the excellent EGOR activity in alkaline medium. The validated enhanced oxidation ability of these Pd/C CeO2 catalysts for the anodic oxidation of other low molecular weight alcohol fuels including methanol and ethanol showcased their application potential toward DMFCs and DEFCs.", "author_names": [ "Sasidharan Sankar", "Naoto Watanabe", "Gopinathan M Anilkumar", "Balagopal N Nair", "Sailaja G Sivakamiammal", "Takanori Tamaki", "Takeo Yamaguchi" ], "corpus_id": 104346515, "doc_id": "104346515", "n_citations": 16, "n_key_citations": 0, "score": 0, "title": "Electro oxidation competency of palladium nanocatalysts over ceria carbon composite supports during alkaline ethylene glycol oxidation", "venue": "", "year": 2019 }, { "abstract": "This Review article provides a report on progress in the synthesis, properties and catalytic applications of noble metal based composite nanomaterials. We begin with a brief discussion on the categories of various composite materials. We then present some important colloidal synthetic approaches to the composite nanostructures; here, major attention has been paid to bimetallic nanoparticles. We also introduce some important physiochemical properties that are beneficial from composite nanomaterials. Finally, we highlight the catalytic applications of such composite nanoparticles and conclude with remarks on prospective future directions.", "author_names": [ "Yuanfang Xu", "Liquan Chen", "Xuchun Wang", "Wei Yao", "Qiao Zhang" ], "corpus_id": 205977413, "doc_id": "205977413", "n_citations": 108, "n_key_citations": 1, "score": 0, "title": "Recent advances in noble metal based composite nanocatalysts: colloidal synthesis, properties, and catalytic applications.", "venue": "Nanoscale", "year": 2015 }, { "abstract": "Abstract The multi walled carbon nanotubes (MWNTs) are introduced as reductants to prepare bimetallic PtNix composite nanocatalysts via a hydrothermal reaction for the investigation of ethanol oxidation reaction (EOR) The crystal structure and elemental analysis of PtNix/MWNTs nanocatalysts are characterized by X ray diffraction (XRD) and energy dispersive X ray spectroscopy (EDS) respectively. The morphologies of these nanocatalysts are observed by transmission electron microscopy (TEM) and scanning electron microscope (SEM) The results reveal that the PtNix nanocatalysts with a nanoparticle size ranging from 6 to 13 nm are immobilized on the surface of MWNTs. The electrocatalytic activities of the PtNix/MWNTs nanocatalysts for EOR in alkaline media are examined using cyclic voltammetry (CV) electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) The onset potential of EOR in the nanocatalyst of PtNi3/MWNTs is negatively shifted for about 190 mV as compared to that in the nanocatalyst of Pt/MWNTs. The current for the forward anodic peak of EOR in the PtNi3/MWNTs nanocatalyst is about 2.5 times higher than that of pure Pt/MWNTs.", "author_names": [ "Ke-qiang Ding", "Zhao Yongbo", "Likun Liu", "Yanli Cao", "Qingfei Wang", "Hongbo Gu", "Xingru Yan", "Zhanhu Guo" ], "corpus_id": 13844082, "doc_id": "13844082", "n_citations": 32, "n_key_citations": 0, "score": 0, "title": "Pt Ni bimetallic composite nanocatalysts prepared by using multi walled carbon nanotubes as reductants for ethanol oxidation reaction", "venue": "", "year": 2014 }, { "abstract": "Palladium is considered as an efficient anode catalyst with high catalytic activity for electrooxidation of formic acid.To further improve the catalytic activity and stability, alloying or surface modification with Sb is an effective way. In this work, the well dispersed carbon supported Pd Sb composite nanocatalysts(Pd Sb/C) were synthesized by traditional impregnation reduction method with trisodium citrate as the complexing agent, sodium borohydride as the reducing agent. The morphologies of Pd Sb/C and the effects of molar ratio of Pd to Sb on the electrocatalytic properties of Pd Sb/C for HCOOH electrooxidation were studied.The XRD and XPS analyses on the as prepared Pd Sb/C catalyst revealed that Sb(0) was presented on the Pd surface, and the immature alloying of Pd with Sb was achieved. Cyclic voltammetryic and chronoamperometric studies indicated a volcano shaped relationship between Sb content and electrocatalytic activity with an optimum molar ratio of Pd:Sb=20:1. Compared with the commercial Pd/C catalyst, the Pd Sb/C(20:1) presented the highest electrocatalytic activity and best stability. This enhancement may be attributed to the electronic effect and bi functional effect induced by addition of Sb onto Pd surface, resulting in a weaker adsorption and accelerated oxidative removal of CO poison formed during HCOOH electrooxidation.", "author_names": [ "Wang Long-lon" ], "corpus_id": 101328479, "doc_id": "101328479", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Preparation and Characterization of Carbon Supported Pd Sb Composite Nanocatalysts for Formic Acid Electrooxidation", "venue": "", "year": 2015 }, { "abstract": "Supported gold catalysts have attracted intensive interest due to their unique catalytic properties. The easy sintering of gold particles, however, is still the major obstacle to the practical application of gold catalysts. Herein, a highly active and sintering resistant TiO2 hydroxyapatite (HAP, Ca10(PO4)6(OH)2) composite supported gold catalyst was prepared by a deposition precipitation method. TEM results manifested TiO2 HAP had smaller gold nanoparticles than TiO2 and HAP. Patterns of TG DTG revealed that the presence of HAP inhibited the phase transformation from anatase to rutile. Based on UV Vis and BET studies, HAP prevented the formation of large TiO2 agglomerates, leading to higher dispersion of TiO2 nanoparticles in TiO2 HAP composites. Au/TiO2 HAP had the higher activity and sintering resistance compared with Au/TiO2 and Au/HAP for CO oxidation. TiO2 HAP and Au/TiO2 HAP exhibited the best photocatalytic activity among supports and gold nanocatalysts, respectively. Gold nanoparticles could further improve the photocatalytic performance. It was likely that the synergistic interaction among gold nanoparticles, TiO2 and HAP was responsible for the high activity and sintering resistance of Au/TiO2 HAP.Graphical Abstract", "author_names": [ "Jiuli Guo", "Feng Dong", "Siyuan Zhong", "Baolin Zhu", "Weiping Huang", "Shoumin Zhang" ], "corpus_id": 104107601, "doc_id": "104107601", "n_citations": 8, "n_key_citations": 0, "score": 0, "title": "TiO2 Hydroxyapatite Composite as a New Support of Highly Active and Sintering Resistant Gold Nanocatalysts for Catalytic Oxidation of CO and Photocatalytic Degradation of Methylene Blue", "venue": "Catalysis Letters", "year": 2017 } ]

[ { "abstract": "Introduction. Part 1: Physics. Polarized light and gyrotropic media. Magnetooptical effects. Light waveguiding in thin magnetic films. Microscopical mechanisms of magnetooptical activity. Magnetooptical effects in the x ray region. Domain structure. Part 2: Magnetooptical Methods. Dielectrics. Ferrimagnetic garnets. Metals and alloys. Semimagnetic semiconductors. Bilayer, multilayer, superlattice and granular structures. Part 3: Applied Magnetooptics. Thin film magnetooptical devices. Magnetooptical memories, disks and tapes. Integrated magnetooptics. Integrated magnetooptical devices. References. Index.", "author_names": [ "Anatolii K Zvezdin", "V A Kotov" ], "corpus_id": 137690056, "doc_id": "137690056", "n_citations": 666, "n_key_citations": 36, "score": 1, "title": "Modern magnetooptics and magnetooptical materials", "venue": "", "year": 1997 }, { "abstract": "", "author_names": [ "Henryk Szymczak" ], "corpus_id": 117175243, "doc_id": "117175243", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Reviews of Books. (A.K. Zvezdinm, V.A. Kotov (1997) Modern Magnetooptics and Magnetooptical Materials.", "venue": "", "year": 1997 }, { "abstract": "In this review new nanostructured materials for magnetooptics are discussed: magnetic photonic crystals and magnetic perforated metal/dielectric films. It is shown that under some conditions the magnetooptical effects in such structures can be significantly enhanced remaining the optical transmittance on a relatively high level. This effect is primarily due to the proper structuring of the material on a nanoscale. Special attention is paid to magnetic substances which are most appropriate for modern magnetooptics.", "author_names": [ "Vladimir I Belotelov", "V A Kotov", "Anatolii K Zvezdin" ], "corpus_id": 100267348, "doc_id": "100267348", "n_citations": 9, "n_key_citations": 0, "score": 0, "title": "New magnetooptical materials on a nanoscale", "venue": "", "year": 2006 }, { "abstract": "", "author_names": [ "An Teng Gong Er" ], "corpus_id": 161749410, "doc_id": "161749410", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A. K. Zveadin and V. A. Kotpw, Modern Magnetiooptical and Magnetooptical Materials Institute of Physica Pubrishing, Bristol and Philadelphia, 1997, x+viii+368p. 24x16.5cm, \\30,970 [Da Xue Yuan Xiang Zhuan Men Shu", "venue": "", "year": 1998 }, { "abstract": "In this paper we report results of magnetooptical measurements done on standard InAs MOCVD layers grown on GaAs. Extremely narrow lines (half widths of the order of 20 mT) narrower than found by other authors in high quality MBE InAs epilayers on GaAs as well as the lines of typical half widths have been found both in the photoconductivity spectra and in the transmission spectra. A detailed comparison with the theoretical dependence of shallow donor and Landau level energies on magnetic field leads to the conclusion that they originate from cyclotron resonance and impurity shifted cyclotron resonance transitions in that material. PACS numbers: 72.40.+w, 71.55. i, 78.30. m", "author_names": [ "Tomasz Andrearczyk", "Krzysztof Karpierz", "And M Grynberg" ], "corpus_id": 55264458, "doc_id": "55264458", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "FIR MAGNETOOPTICAL MEASUREMENTS ON MOCVD GROWN", "venue": "", "year": 2013 }, { "abstract": "The magnetooptics of an asymmetric layered waveguide structure is discussed to investigate the possibility of creating new devices that combine both nonreciprocity and nonlinearity. After addressing some fundamental magnetooptic properties and the kind of materials needed, a straightforward envelope theory is given that exploits the Voigt effect instead of the more obvious Faraday effect. It is emphasised that this choice leads to desirable design features. It is proposed that the introduction of an applied magnetic field to a waveguide structure can be achieved through the use of thin current carrying strips. It is emphasised that the strips can be arranged to any degree of complexity and that a high degree of control over spatial soliton dynamics can be achieved. Spatial soliton light beams are selected because they can be generated, within a waveguide, in a stable form. The attractive features of using the type of magnetooptic waveguide investigated here are highlighted with examples and it is concluded that the formats proposed can be used for the fully integrated isolator capacity that modern laser systems demand.", "author_names": [ "Allan D Boardman", "M Q Xie" ], "corpus_id": 118368520, "doc_id": "118368520", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Magnetooptics in layered nonlinear structures", "venue": "", "year": 2003 }, { "abstract": "Magnetic materials have attracted considerable attention for their applications in high density magneto optical storage devices, which is not only appealing scientifically, but also makes the magnetic materials promising for a wide range of applications [1 11] Due to their unique optical properties, magnetic materials have been introduced into the photonic crystals, forming magnetophotonic crystals (MPCs) i.e. the photonic crystals with at least one magnetic material component [2,3] Now the optical properties can be mediated and controlled by the external electric or magnetic field due to the existence of magnetic materials. The special importance of MPCs can be ascribed to the existence of magnetooptical effects, for example, Kerr effect and Faraday rotation [12 28] They were discovered by Kerr and Faraday, respectively, and are now widely used in integrated optics and magneto optical devices for magnetic domain imaging, mapping of hysteresis loops and high density recording [6] Magnetic materials with large magneto optical responses are always the attractive ones used in magnetophotonic crystals. In contrast to the corresponding three dimensional magnetic structures, magnetic materials exhibit a larger magneto optical effects due to the light's confinement in the MPCs, offering a genuine chance to put their optical responses into applications. The optimized MPCs have been shown to behave like mixed systems, with a coexistence of high transmittance and large magneto optical effects [12 28] All possible configurations are proposed to achieve strong magneto opitcal effects, including the ordinary cavity based, multilayered periodic and aperiodic structures. Furthermore, the diffracted magneto optical enhancement is also demonstrated in the grating structures theoretically and experimentally, which greatly reduces the thickness of the device contrary to multilayered structures and miniaturizes magneto optical devices in integrated optics [29,30] The ability to tune the otpical properties by an external stimulus is a key issue of modern optoelectronics. Although most attention has so far been focused on the magneto optical properties of the given structures, tunable magneto optical devices have important applications and will be respected in optical switches and displays. There are few reports concerning with the tunable magnetophotonic crystals [31 33] For example, it is possible to manipulate the magnetic order of magnetic conducting spheres using the magnetic field, thus forming the tunable magnetophotonic crystals [31] Semiconductor quantum well has O pe n A cc es s D at ab as e w w w .in te ch w eb .o rg", "author_names": [ "Haixia Da", "Zhen Yuan Li" ], "corpus_id": 201635942, "doc_id": "201635942", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "3 Manipulating Nematic Liquid Crystals based Magnetophotonic Crystals", "venue": "", "year": 2018 }, { "abstract": "We demonstrate a novel approach to the control of the collapse of optical beams in Kerr media. To this end, we consider a combination of two magnetooptical (MO) phenomena, the Cotton Mouton and Faraday effects, in order to introduce a suitable and tunable interplay between the induced linear and circular birefringences. Our numerical analysis confirms that a properly applied external magnetic field may alter the dynamics of the beam propagation in magnetic self focusing bulk Kerr media. For a chosen value of the optical power, the acceleration, the delay or even the arrest of the collapse can be achieved. We demonstrate experimentally the magnetically induced acceleration of the collapse in a ferrimagnetic yttrium iron garnet crystal (YIG) Full Text: PDF References: R.W. Boyd, Nonlinear optics (San Diego, Academic Press 2008) C. Sulem, P.L. Sulem, The nonlinear Schrodinger equation: self focusing and wave collapse (New York, Springer 1999) L. Berge, \"Wave collapse in physics: principles and applications to light and plasma waves\" Phys. Rep. 303, 259 (1998) [CrossRef] Y.S. Kivshar, D.E. Pelinovsky, \"Self focusing and transverse instabilities of solitary waves\" Phys. Rep. 331, 117 (2000) [CrossRef] B.A. Malomed, D. Mihalache, F. Wise, and L. Torner, \"Spatiotemporal optical solitons\" J. Optics B: Quant. Semicl. Opt. 7, R53 (2005) [CrossRef] M. Peccianti, K.A. Brzdakiewicz, G. Assanto, \"Nonlocal spatial soliton interactions in nematic liquid crystals\" Opt. Lett. 27, 1460 (2002) [CrossRef] O. Bang, W. Krolikowski, J. Wyller, J.J. Rasmussen, \"Collapse arrest and soliton stabilization in nonlocal nonlinear media\" Phys. Rev. E 66, 046619 (2002) [CrossRef] R. Kurzynowski, W.A. Wozniak, \"Superposition rule for the magneto optic effects in isotropic media\" Optik 115, 473 (2004) [CrossRef] A.K. Zvezdin, V.A. Kotov, Modern Magnetooptics and Magneto optical Materials (New York, Taylor and Francis 1997) Y. Linzon, K.A. Rutkowska, B.A. Malomed, R. Morandotti, \"Magneto optical Control of Light Collapse in Bulk Kerr Media\" Phys. Rev. Lett. 103, 053902 (2009) [CrossRef] B.A. Malomed, in Progress in Optics 43, 71 (E. Wolf, North Holland, Amsterdam, 2002) R.Y. Chiao, E. Garmire, C.H. Townes, \"Self Trapping of Optical Beams\" Phys. Rev. Lett. 13, 479 (1964) [CrossRef]", "author_names": [ "Katarzyna A Rutkowska", "Yoav Linzon", "Boris A Malomed", "Roberto Morandotti" ], "corpus_id": 121403970, "doc_id": "121403970", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Control of nonlinear collapse in magnetooptical Kerr media", "venue": "", "year": 2009 }, { "abstract": "UDC 681.41:773.92 We study the effect of the duration of ultraviolet irradiation of D 1 and D 2 photopolymerizable compositions on some physicomechanical properties of a photopolymeric material obtained in the process of photopolymerization. It is shown that these properties become most pronounced for a certain fixed duration of ultraviolet treatment and, hence, continuation of this process becomes unreasonable. The degree of conversion c~ of photopolymeric materials does not exceed 70% Strength and some other characteristics of photopolymers can be improved by additional treatment of the material with high frequency currents. This kind of treatment is characterized by lower power consumption and can be performed much faster than routine thermal treatment (by about two orders of magnitude) Modern personal computers employ magnetooptical data storage devices. Optical disks are characterized by much higher densities of data (10 4 10 5 bits/mm2) which are written and read by a focused laser beam, and greater resistance to the action of external factors [1] The technology of their production includes the following processes: manufacturing of the originals (matrices) of optical disks, copying of optical disks by photochemical patterning (2R process) from liquid photopolymerizable compositions, and thermal treatment of the produced disks to improve and stabilize their physicomechanical properties. (Other methods for copying of optical disks, namely, casting under pressure and molding are not considered here. The last technological operation is traditionally performed by convective heating for several (up to 10) hours. The long duration of this process and high energy consumption increase the cost of optical disks. It is known that dielectrics can be efficiently heated by high frequency currents [2] moreover, this procedure guarantees simultaneous uniform and fairly rapid heating of the entire volume of the specimen. In this paper, we establish an optimal mode of high frequency treatment of optical disks. We studied two photopolymerizable compositions: D 1 and D 2. The D 1 composition consists of OCMC 2 oligocarbonatemethacrylate, TGM 3 trioxyethylenedimethacrylate playing the role of a binding oligomer, and isobutyl ether benzoin (IBEB) as a photoinitiator. The D 2 composition is additionally enriched with MDF 2 oligoetheracrylate. To produce high quality copies of optical disks, the industrial oligomers are kept in a vacuum under a pressure of 1.33 kPa for 3 h. The prepared photopolymerizable compositions are filtered to remove residual solvents and unnecessary impurities and to enhance their stability and working life [3] The compositions obtained as a result are subjected to the action of ultraviolet radiation and undergo polymerization according to the freeradical mechanism. The process of polymerization goes layer by layer [4] Specimens were prepared for testing in a stack between two polished glasses (the gap between the glasses was filled with the liquid photopolymerizable compositions) and irradiated on both sides by panels of LUF 80 ultraviolet lamps at a distance of 150 mm from the surface (illumination energy was 45 W/m z) [5]", "author_names": [ "Liang Ka", "R I Mervins ' kyi" ], "corpus_id": 136077155, "doc_id": "136077155", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "OPTIMIZATION OF PHYSICOMECHANICAL PROPERTIES OF PHOTOPOLYMERIC MATERIALS FOR OPTICAL DATA STORAGE BY TREATMENT WITH HIGH FREQUENCY CURRENTS", "venue": "", "year": 1994 }, { "abstract": "Vapor cells with antirelaxation coating are widely used in modern atomic physics experiments due to the coating's ability to maintain the atoms' spin polarization during wall collisions. We characterize the performance of vapor cells with different coating materials by measuring longitudinal spin relaxation and vapor density at temperatures up to 95*C. We found that the spin projection noise limited sensitivity for atomic magnetometers with such cells improves with temperature, which demonstrates the potential of antirelaxation coated cells in applications of future high sensitivity magnetometers. (c) 2016 Optical Society of America OCIS codes: (020.0020) Atomic and molecular physics; (120.0120) Instrumentation, measurement, and metrology; (230.0230) Optical devices. References and links 1. D. Budker and M. Romalis, \"Optical magnetometry,\" Nat. Phys. 3, 227 (2007) 2. D. Budker, L. Hollberg, D. F. Kimball, J. Kitching, S. Pustelny, and V. Yashchuk, \"Microwave transitions and nonlinear magneto optical rotation in anti relaxation coated cells,\" Phys. Rev. A 71, 012903 (2005) 3. B. Julsgaard, J. Sherson, J. I. Cirac, J. Fiurasek, and E. S. Polzik, \"Experimental demonstration of quantum memory for light,\" Nature 71, 482 (2004) 4. A. Kuzmich, L. Mandel, and N. P. Bigelow, \"Generation of spin squeezing via continuous quantum nondemolition measurement,\" Phys. Rev. Lett. 85, 1594 (2000) 5. S. Pustelny, D. F. Jackson Kimball, C. Pankow, M. P. Ledbetter, P. Wlodarczyk, P. Wcislo, M. Pospelov, J. R. Smith, J. Read, W. Gawlik, and D. Budker, \"The Global Network of Optical Magnetometers for Exotic physics (GNOME) A novel scheme to search for physics beyond the Standard Model,\" Ann. Phys. 525, 659 (2013) 6. S. Pustelny, D. Jackson Kimball, S. Rochester, V. Yashchuk, and D. Budker, \"Influence of magnetic field inhomogeneity on nonlinear magneto optical resonances,\" Phys. Rev. A 74, 063406 (2006) 7. M. A. Bouchiat and J. Brossel, \"Relaxation of optically pumped Rb atoms on paraffin coated palls,\" Phys. Rev. 147, 41 (1966) 8. V. Liberman and R. J. Knize, \"Relaxation of optically pumped Cs in wall coated cells,\" Phys. Rev. A 34, 5115 (1986) 9. M. Graf, D. Kimball, S. Rochester, K. Kerner, C. Wong, D. Budker, E. Alexandrov, M. Balabas, and V. Yashchuk, \"Relaxation of atomic polarization in paraffin coated cesium vapor cells,\" Phys. Rev. A 72, 023401 (2005) 10. T. Karaulanov, M. Graf, D. English, S. Rochester, Y. Rosen, K. Tsigutkin, D. Budker, E. Alexandrov, M. V. Balabas, D. F. Kimball, F. Narducci, S. Pustelny, and V. Yashchuk, \"Controlling atomic vapor density in paraffin coated cells using light induced atomic desorption,\" Phys. Rev. A 79, 012902 (2009) 11. M. V. Balabas, K. Jensen, W. Wasilewski, H. Krauter, L.S. Madsen, J.H. Muller, T. Fernholz, and E.S. Polzik, \"High quality anti relaxation coating material for alkali atom vapor cells,\" Opt. Express 18, 5825 (2010) 12. M. V. Balabas, \"Dependence of the longitudinal relaxation time of the polarization of cesium atoms in the ground state on the temperature of an antirelaxation coating,\" Tech. Phys. 55, 1324 (2010) 13. M. V. Balabas and O. Y. Tret'yak, \"Temperature dependence of the kinetics of irreversible escape of cesium atoms from a vapor phase into an antirelaxation coating,\" Tech. Phys. 57, 1257 (2012) 14. K. Nasyrov, S. Gozzini, A. Lucchesini, C. Marinelli, S. Gateva, S. Cartaleva, and L. Marmugi, \"Antirelaxation coatings in coherent spectroscopy: Theoretical investigation and experimental test,\" Phys. Rev. A 92, 043803 (2015) 15. S. J. Seltzer, D. J. Michalak, M. H. Donaldson, M. V. Balabas, S.K. Barber, S. L. Bernasek, M. A. Bouchiat, A. Hexemer, A. M. Hibberd, D. F. Kimball, C. Jaye, T. Karaulanov, F. A. Narducci, S. A. Rangwala, H. G. Robinson, A. K. Shmakov, D.L. Voronov, V. V. Yashchuk, A. Pines, and D. Budker, \"Investigation of antirelaxation coatings for alkali metal vapor cells using surface science techniques,\" J. Chem. Phys. 133, 144703 (2010) 16. M. V. Balabas, T. Karaulanov, M. P. Ledbetter, and D. Budker, \"Polarized alkali metal vapor with minute long transverse spin relaxation time,\" Phys. Rev. Lett. 105, 070801 (2010) 17. M. V. Balabas and O. Y. Tretiak, \"Comparative study of alkali vapour cells with alkane alkeneand 1 nonadecylbenzene based antirelaxation wall coatings,\" Quantum Electron. 43, 1175 (2013) 18. K. Jensen, R. Budvytyte, R. A. Thomas, T. Wang, A. Fuchs, M. V. Balabas, G. Vasilakis, L. Mosgaard, T. Heimburg, S. Olesen, and E.S. Polzik, \"Non invasive detection of animal nerve impulses with an atomic magnetometer operating near quantum limited sensitivity,\" arXiv:1601.03273 (2016) 19. J. Kitching, S. Knappe, and L. Hollberg, \"Miniature vapor cell atomic frequency references,\" Appl. Phys. Lett. 81, 553 (2002) 20. M. P. Ledbetter, I. M. Savukov, V. M. Acosta, D. Budker, and M. V. Romalis, \"Spin exchangerelaxation free magnetometry with Cs vapor,\" Phys. Rev. A 77, 1 (2008) 21. S. J. Seltzer and M. V. Romalis, \"High temperature alkali vapor cells with antirelaxation surface coatings,\" J. Appl. Phys. 106, 114905 (2009) 22. C. Rahman and H. G. Robinson, \"Rb O O hyperfine transition in evacuated wall coated cell at melting temperature,\" IEEE J. Quantum Electron. 23, 452 (1987) 23. J. Vanier, R. Kunski, A. Brisson, and P. Paulin, \"Progress and prospects in rubidium frequency standards,\" J. Phys. 42, 139 (1981) 24. D. Budker and D. F. Kimball, Optical Magnetometry (Cambridge University, 2013) 25. It is often the transverse spin relaxation time (T2) that appears in Eq. (1) to represent the spin relaxation time trel. Since the transverse spin relaxation time is limited by the longitudinal spin relaxation time (T1) (T2 2T1, which is the regime where atomic magnetometers are often operated) we use T1 to represent the spin relaxation time trel in Eq. (1) to study the fundamental limit to the magnetometric sensitivity. 26. W. Franzen, \"Spin relaxation of optically aligned rubidium vapor,\" Phys. Rev. 115, 850 (1959) 27. W. Chalupczak, P. Josephs Franks, R. M. Godun, and S. Pustelny, \"Radio frequency spectroscopy in the dark,\" Phys. Rev. A 88, 052508 (2013) 28. V. V. Yashchuk, D. Budker, and J. R. Davis, \"Laser frequency stabilization using linear magnetooptics,\" Rev. Sci. Instrum. 71, 341 (2000) 29. Even larger locking ranges may be achieved with DAVLLs operated at alleviated temperatures [35] or systems using buffer gas cells [36] 30. S. Rochester, AtomicDensityMatrix v15.08.27 (2015) 31. S. J. Seltzer, M. A. Bouchiat, and M. V. Balabas, \"Surface coatings for atomic magnetometry,\" in Optical Magnetometry, D. Budker and D. F. Kimball, ed. (Cambridge University, 2013) Chap. 11, pp. 205 224. 32. N. Sekiguchi and A. Hatakeyama, \"Non negligible collisions of alkali atoms with background gas in buffer gas free cells coated with paraffin,\" Appl. Phys. B 122, 81 (2016) 33. E. Zhivun, A. Wickenbrock, J. Sudyka, S. Pustelny, B. Patton, and D. Budker, \"Light shift averaging in paraffin coated alkali vapor cells,\" arXiv:1511.05345 (2015) 34. N. Bhaskar, J. Pietras, J. Camparo, W. Happer, and J. Liran, \"Spin destruction in collisions between cesium atoms,\" Phys. Rev. Lett. 44, 930 (1980) 35. A. L. Marchant, S. Handel, T. P. Wiles, S. A. Hopkins, C. S. Adams, and S. L. Cornish, \"Offresonance laser frequency stabilization using the Faraday effect,\" Opt. Lett. 36, 64 (2011) 36. S. Pustelny, V. Schultze, T. Sholtes, and D. Budker, \"Dichroic atomic vapor laser lock with multigigahertz stabilization range,\" arXiv:1512.08919 (2015) 37. E. Zhivun, A. Wickenbrock, B. Patton, and D. Budker, \"Alkali vapor magnetic resonance driven by fictitious radiofrequency fields,\" Appl. Phys. Lett. 105, 192406 (2014)", "author_names": [ "Wenhao Li", "Mikhail V Balabas", "Xiang Peng", "S Pustelny", "Arne Wickenbrock", "Hong Guo", "Dmitry Budker" ], "corpus_id": 54825552, "doc_id": "54825552", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Title Characterization of high temperature performance of cesium vapor cells with anti relaxation coating Permalink", "venue": "", "year": 2016 } ]

[ { "abstract": "Wide bandgap semiconductors are extremely attractive for the gamut of power electronics applications from power conditioning to microwave transmitters for communications and radar. Of the various materials and device technologies, the AlGaN/GaN high electron mobility transistor seems the most promising. This paper attempts to present the status of the technology and the market with a view of highlighting both the progress and the remaining problems.", "author_names": [ "Umesh K Mishra", "Primit Parikh", "Yifeng Wu" ], "corpus_id": 12839833, "doc_id": "12839833", "n_citations": 1460, "n_key_citations": 35, "score": 1, "title": "AlGaN/GaN HEMTs an overview of device operation and applications", "venue": "Proc. IEEE", "year": 2002 }, { "abstract": "The research presents AlGaN/GaN HEMTs device characterizations at different temperatures using physics based numerical simulation. Industry standard simulation tool Silvaco ATLAS is used to characterize the various electronic properties of the device. An extensive theoretical overview is done to achieve the most comprehensive values for GaN and AlGaN properties, as discussed in the paper. This research is mainly focused on simulation of temperature dependent device performances as well as on some other material properties that are not well defined in ATLAS. Energy bandgap, density of states, saturation velocities, surface traps, polarization effect, carrier lifetime and mobility, permittivity, effective Richardson's constant, and donor and acceptor energy levels are considered as critical parameters for predicting temperature effect in ALGaN/GaN HEMT. Various aspects of device performance are analyzed at high temperature along with the different bias configurations.", "author_names": [ "Hasina F Huq", "Bashirul Polash" ], "corpus_id": 31976221, "doc_id": "31976221", "n_citations": 4, "n_key_citations": 0, "score": 0, "title": "Physics based numerical simulation and device characterizations of AlGaN/GaN HEMTs with temperature effects", "venue": "Microelectron. J.", "year": 2011 }, { "abstract": "As GaN based amplifier technology is garnering interest due to its inclusion into major proposed DoD systems, we look to extend the operating frequency and scale the output power of the technology to the millimeter wavelength (MMW) regime (30 300 GHz) Enabling power performance in this frequency range not only entails geometric device scaling, but also requires novel heterostructure and device design to facilitate simultaneous high frequency response and high operating voltage. In this regard, it cannot be assumed that the reliability of previous frequency nodes will extend into the MMW regime. In this talk, an overview of the challenges and tradeoffs of scaling GaN based devices will be presented as well as a look into NRL's approach to MMW GaN HEMT design including initial reliability data at 40 GHz.", "author_names": [ "Brian P Downey" ], "corpus_id": 64077980, "doc_id": "64077980", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "GaN HEMTs for millimeter wavelength power amplifiers", "venue": "", "year": 2014 }, { "abstract": "Due to its outstanding materials properties the semiconductor system (Al,Ga)N is a very promising candidate for high power electronic applications covering communication, radar and power conversion. In fact GaN is already considered to be the most important semiconductor besides silicon. In this invited contribution we give an overview of epitaxial growth, device processing, characterization and reliability assessment of electronic devices based on this material.", "author_names": [ "Patrick Waltereit", "Wolfgang Bronner", "Peter Bruckner", "Michael Dammann", "Richard Reiner", "S Muller", "Jutta Kuhn", "Michael Muser", "Ruediger Quay", "Michael Mikulla", "Oliver Ambacher" ], "corpus_id": 56238147, "doc_id": "56238147", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Recent developments in GaN HEMTs and MMICs for high power electronics", "venue": "", "year": 2013 }, { "abstract": "Cuvillier Verlag Jun 2012, 2012. Taschenbuch. Book Condition: Neu. 208x147x14 mm. Neuware Gallium nitride (GaN) based High Electron Mobility Transistors (HEMTs) for high voltage, high power switching and regulating for space applications are studied in this work. Efficient power switching is associated with operation in high OFF state blocking voltage while keeping the ON state resistance, the dynamic dispersion and leakage currents as low as possible. The potential of such devices to operate at high voltages is limited by a chain of factors such as subthreshold leakages and the device geometry. Blocking voltage enhancement is a complicated problem that requires parallel methods for solution; epitaxial layers design, device structural and geometry design, and suitable semiconductor manufacturing technique. In this work physical based device simulation as an engineering tool was developed. An overview on GaN based HEMTs physical based device simulation using Silvaco oATLASo is given. The simulation is utilized to analyze, give insight to the modes of operation of the device and for design and evaluation of innovative concepts. Physical based models that describe the properties of the semiconductor material are introduced. A detailed description of the specific AlGaN/GaN HEMT structure definition and geometries are given along with the complex fine meshing requirements. Nitride semiconductor specific material.", "author_names": [ "Eldad Bahat Treidel" ], "corpus_id": 44900354, "doc_id": "44900354", "n_citations": 21, "n_key_citations": 4, "score": 0, "title": "GaN Based HEMTs for High Voltage Operation. Design, Technology and Characterization", "venue": "", "year": 2012 }, { "abstract": "GaN based devices are creating a technological revolution and are expected to replace silicon transistors for the development of high efficiency power converters. For this reason, a significant research effort is being spent towards the fabrication of high performance and high reliability GaN transistors. Despite this, the reliability of GaN HEMTs is still limited by a number of factors, that can significantly reduce device lifetime and lead to early failures. This paper presents an overview of the physical processes responsible for the failure of GaN transistors for power electronics, with focus on: (i) degradation under off state conditions; (ii) degradation in semi on conditions; (iii) degradation in the on state (positive gate bias) The results presented here help understanding the most common degradation modes of GaN devices and can be used to improve manufacturing technology.", "author_names": [ "Gaudenzio Meneghesso", "Matteo Meneghini", "Carlo de Santi", "Enrico Zanoni" ], "corpus_id": 174820282, "doc_id": "174820282", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "GaN based lateral and vertical devices: physical mechanisms limiting stability and reliability", "venue": "2019 Electron Devices Technology and Manufacturing Conference (EDTM)", "year": 2019 }, { "abstract": "An overview of a surface potential (SP) based model for AlGaN/GaN HEMTs named \"Advanced SPICE Model for High Electron Mobility Transistor\" (ASM HEMT) is presented in this paper. Recently, our model has been selected as industry standard model for GaN HEMTs by Si2 Compact Model Coalition (CMC) after more than five years of rigorous evaluation and testing by semiconductor companies. In our model, we preserve the 2DEG nature of the channel by self consistently solving the Schrodinger's and Poisson's equations to obtain an analytical expression for the surface potential after considering two energy sub bands in the triangular quantum well at the hetero interface. We proceed to calculate all other important quantities such as the intrinsic charges, drain current etc. in terms of the surface potential, valid for a wide range of bias conditions. We have incorporated real device effects such as Access Resistances, Drain Induced Barrier Lowering (DIBL) Mobility Degradation, Channel Length Modulation, SelfHeating, Gate Current, Noise, Field Plates etc. We have a working trap model incorporated into the main model and it is validated against pulsed IV measurements, harmonic balance power sweeps and load pull for a commercial RF GaN HEMT. We have also validated the model for power devices with field plates and have been able to accurately capture the capacitances incorporated due to the field plates.", "author_names": [ "Sheikh Aamir Ahsan", "Yogesh Singh Chauhan", "Raghvendra Dangi", "Saptarshi Ghosh", "Sourabh Khandelwal", "Ahtisham Pampori" ], "corpus_id": 53359668, "doc_id": "53359668", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "ASM HEMT: Industry Standard GaN HEMT Model for Power and RF Applications", "venue": "", "year": 2018 }, { "abstract": "The purpose of this invited paper is to give readers a comprehensive and critical overview on how to extract equivalent circuit models for GaN HEMTs, which are the preferred devices for high power high frequency applications. This overview is meant to provide a practical modeling know how for this advanced type of transistor, in order to support its development for improving device technology and circuit design. With the aim to broaden knowledge to empower models, experimental results are presented as illustrative examples of the most crucial challenges faced by the microwave engineers in modeling high power GaN HEMTs. All the relevant aspects are covered, going from linear (also noise) to nonlinear models. The analysis is mainly focused on the modeling of distinctive peculiarities of GaN HEMTs. Particular attention is paid to study the importance of accurately modeling the kink effect in the output reflection coefficient, because of the relatively high transconductance, the peak in the magnitude of the short circuit current gain, because of the relatively large intrinsic capacitances, and the low frequency dispersion, because of trapping and thermal effects. Furthermore, to emphasize the key role of accurate device models for a successful circuit design, a practical example of power amplifier is discussed. Copyright (c) 2015 John Wiley Sons, Ltd.", "author_names": [ "Giovanni Crupi", "Valeria Vadala", "Paolo Colantonio", "Elisa Cipriani", "Alina Caddemi", "Giorgio Vannini", "Dominique M M -P Schreurs" ], "corpus_id": 112423231, "doc_id": "112423231", "n_citations": 22, "n_key_citations": 0, "score": 0, "title": "Empowering GaN HEMT models: The gateway for power amplifier design", "venue": "", "year": 2017 }, { "abstract": "The hydride vapor phase epitaxy technique has been used to grow bulk GaN crystals for processing into freestanding substrates for optoelectronic and microelectronic applications. Substrates up to 2 inches in diameter were fabricated and tested for materials properties and device applications. Defect densities as low as 5x10 cm were measured via CL imaging. Semiinsulating electrical behavior was achieved through Fe doping with room temperature resistivity measurements as high as 2x10 O*cm measured using COREMA. Schottky diodes with >600V breakdown voltage and 20 ns reverse recovery time were fabricated. AlGaN/GaN HEMTs were fabricated and tested, resulting in an output power density of 5.0 W/mm at 2 GHz with a poweradded efficiency of 35% and an associated gain of 14.5 dB. This constitutes the first report of significant power density from MBE grown HEMTs on freestanding HVPE GaN substrates.", "author_names": [ "Andrew D Hanser", "L Liu", "Edward Alfred Preble", "Denis V Tsvetkov", "M Tutor", "N Mark Williams", "Keith R Evans", "Y Zhou", "D Wang", "Claude Ahyi", "Chin-Che Tin", "J Williams", "M Park", "David F Storm", "D Scott Katzer", "S C Binari", "Jason A Roussos", "Jeffrey A Mittereder" ], "corpus_id": 171083117, "doc_id": "171083117", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "An Overview of Gallium Nitride Substrate Materials Developments for Optoelectronic and Microelectronic Applications", "venue": "", "year": 2006 }, { "abstract": "In this paper, we aim to present an overview of a surface potential (SP) based model named \"Advanced Spice Model for High Electron Mobility Transistor\" (ASM HEMT) for AlGaN/GaN HEMTs. This model is presently under consideration in the phase III of industry standardization by the Compact Model Coalition (CMC) SP of GaN HEMT is obtained by solving Schrodinger and Poisson equations in the triangular potential well considering the first two energy subbands. The core drain current model and a intrinsic charge model are derived using the developed SP model. Various real device effects like: velocity saturation, drain induced barrier lowering (DIBL) self heating, field dependent mobility, non linear access region resistances etc. are included in the core drain current model to represent real GaN HEMTs. Field plate (FP) model is incorporated to predict accurate current and capacitance trends observed in the high power GaN HEMTs with source and gate connected field plates. Along with the gate current model, non linear trapping effects are also included in the model to capture larghe signal high frequency device behavior. This model is extensively validated with the experimental data of both high power and high frequency GaN HEMTs.", "author_names": [ "Sudip Ghosh", "Sheikh Aamir Ahsan", "Avirup Dasgupta", "Sourabh Khandelwal", "Yogesh Singh Chauhan" ], "corpus_id": 12753657, "doc_id": "12753657", "n_citations": 7, "n_key_citations": 1, "score": 0, "title": "GaN HEMT modeling for power and RF applications using ASM HEMT", "venue": "2016 3rd International Conference on Emerging Electronics (ICEE)", "year": 2016 } ]

[ { "abstract": "A new three phase AC to DC rectifier system with near unity input power factor and reduced input current harmonics is proposed, The proposed approach employs three SCRs and three active semiconductor switches with anti parallel diodes to form a three phase bridge. In the proposed approach only two semiconductor device drops are encountered in the power flow path. Also the DC link inductor is unnecessary and three AC side inductors are used instead. It is shown that discontinuous input current is the preferred mode of operation to realize high quality input current. A suitable control strategy is proposed in order to minimize the input current THD. Further, a zero voltage switching strategy is implemented to minimize the switching losses. The SCRs are suitably phase controlled to limit inrush currents during starting and to provide current limiting action under overload or output short circuit conditions. During normal operation the SCRs are gated to function as diodes. A design procedure for the proposed approach to achieve near sinusoidal input currents and zero voltage switching is detailed. Simulation and experimental results on a laboratory prototype system are discussed.<ETX>", "author_names": [ "Prasad N Enjeti" ], "corpus_id": 110891632, "doc_id": "110891632", "n_citations": 7, "n_key_citations": 0, "score": 1, "title": "A new three phase AC to DC rectifier with active power factor correction", "venue": "Proceedings of 1994 IEEE Applied Power Electronics Conference and Exposition ASPEC'94", "year": 1994 }, { "abstract": "Conventional single phase power factor correction (PFC) rectifiers with active power decoupling capability typically require more than three active switches in their circuits. By exploring the concept of power buffer cell, a new single stage PFC rectifier with two active switches, one inductor and one small power buffering capacitor is reported in this paper. The proposed converter can achieve high power factor, wide output voltage range, and power decoupling function without using electrolytic capacitor. Additionally, an automatic power decoupling control scheme that is simple and easy to implement is proposed in this paper. The operating principle, control method, and design considerations of the proposed rectifier are also provided. A 100 W prototype with ac input voltage of 110 Vrms and a regulated dc output voltage ranging from 30 to 100 V has been successfully designed and practically tested. The experimental results show that with only a 15 mF power buffering film capacitor, the proposed converter can achieve an input power factor of over 0.98, peak efficiency of 93.9% and output voltage ripple of less than 3% at 100 W output power.", "author_names": [ "Sinan Li", "Wenlong Qi", "Siew-Chong Tan", "Shu Yuen Ron Hui" ], "corpus_id": 19592887, "doc_id": "19592887", "n_citations": 37, "n_key_citations": 5, "score": 0, "title": "A Single Stage Two Switch PFC Rectifier With Wide Output Voltage Range and Automatic AC Ripple Power Decoupling", "venue": "IEEE Transactions on Power Electronics", "year": 2017 }, { "abstract": "In this paper, a novel prototype of a zero voltage soft switching PWM three phase AC/DC active power converter with a new transformer assisted quasi resonant tank DC link (TQRDCL) is presented for power factor correction, sinewave line current shaping and constant output DC voltage regulation. The instantaneous space voltage modulated sinewave line current synthesizing scheme of this high power factor active rectifier with an instantaneous output DC power feedback loop is implemented by digital signal processor based software and its related hardware. The simulation results of this soft switched active rectifier are illustrated and discussed as compared with the other resonant DC link rectifiers and hard switched active rectifier.", "author_names": [ "Hideto Yonemori", "Hiroya Fukuda", "Mutsuo Nakaoka" ], "corpus_id": 111210252, "doc_id": "111210252", "n_citations": 13, "n_key_citations": 1, "score": 0, "title": "Advanced three phase ZVS PWM active power rectifier with new resonant DC link and its digital control scheme", "venue": "", "year": 1994 }, { "abstract": "This paper describes a new method to select the optimum sinewave PWM patterns of a large capacity current source fed active PWM AC/DC converter and a practical procedure to design its input AC side low pass filter which is used to suppress higher harmonics flowing Into the utility grid power source. A feasible test is carried out using a 500 kVA active PWM converter which is designed and operated for unique considerations mentioned above. It Is verified that these new considerations are more effective to minimize higher harmonic current components flowing into the utility grid AC line. Furthermore, this experimental work provides highly efficient AC/DC converter characteristics under a unity power factor correction and sinewave line current shaping schemes.", "author_names": [ "Yoshihiro Konishi", "Yutaka Matsumoto", "Prasanna B Boyagoda", "Mutsuo Nakaoka" ], "corpus_id": 57433129, "doc_id": "57433129", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Current fed three phase rectifier with optimum PWM based sinewave line current shaping and unity power factor correction schemes", "venue": "Proceedings of the IECON'97 23rd International Conference on Industrial Electronics, Control, and Instrumentation (Cat. No.97CH36066)", "year": 1997 }, { "abstract": "The conventional three phase rectifier with bulky LC output filter has been widely used in the industry because of its distinctive advantages over the active power factor correction rectifier such as simple circuit, high reliability and low cost. Over 0.9 power factor can be achieved, which is acceptable in most industry applications. This rectifier, however, is not easy to use for high power density applications since the LC filter is bulky and heavy. To solve this problem, a new simple rectifier is presented in this paper. By eliminating the bulky LC filter from the conventional diode rectifier without losing most of the advantages of the conventional rectifier, very high power density power conversion with high power factor can be achieved. Its operating principle and design considerations are illustrated and verified by PSpice simulation and experimental results from a prototype of 3.3 kW rectifier followed by 100 kHz zero voltage switching full bridge PWM power converter.", "author_names": [ "J G Cho", "Chang-Yong Jeong", "Juwon Baek", "D I Song", "Dong-Wook Yoo", "Chung-Yuen Won" ], "corpus_id": 59480155, "doc_id": "59480155", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "High power factor three phase rectifier for high power density AC/DC conversion applications", "venue": "APEC '99. Fourteenth Annual Applied Power Electronics Conference and Exposition. 1999 Conference Proceedings (Cat. No.99CH36285)", "year": 1999 }, { "abstract": "A new application of power and voltage balance control schemes for cascaded H Bridge Multilevel Inverter (CHMI) based Solid State Transformer (SST) topology with fuzzy controller is proposed in this paper. The SST consists of a cascaded multilevel ac/dc rectifier, dual active bridge (DAB) converters with high frequency transformers. The solid state transformer (SST) has the features of immediate voltage regulation, voltage sag compensation, fault isolation, power factor correction, harmonic isolation and dc output. Here we are using the fuzzy controller compared to other controllers i.e. The fuzzy controller is the most suitable for the human decision making mechanism, providing the operation of an electronic system with decisions of experts. To reduce load on the controller and simplify modulation algorithm, a masterslave control (MSC) strategy is designed for the dual active bridge (DAB) stage. This paper presents a compensation strategy based on three phase d q decoupled current controller. The fuzzy controller for a nonlinear system allows for a reduction of uncertain effects in the system control and improve the efficiency. The proposed control method the three phase grid currents and dc link voltage in each module can be simultaneously balanced. By using the simulation results we can analyze that the proposed method and also the performance of the controller and its application to microgrid SST.", "author_names": [ "Lalit Kumar", "S Sunil Naik" ], "corpus_id": 220433126, "doc_id": "220433126", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "A NOVEL THREE PHASE SOLID STATE TRANSFORMER WITH FUZZY CONTROL OF MULTILEVEL CASCADED H BRIDGE INVERTERS", "venue": "", "year": 2017 }, { "abstract": "A new combination of a 'unity power factor three phase rectifier stage' with a quasi resonant SEPIC converter, provides high quality input currents of a transformer isolated three phase AC DC converter. Analysis of the converter, including analysis of the three phase input current waveforms, has been performed and a design procedure developed. Results of a transformer isolated 1.0 kW/35 kHz prototype converter, utilising a single 1200 V IGBT as the active switching device and operating direct off line from a 415 V three phase mains supply, are presented to verify theoretical predictions. The measured input current waveforms, drawn from the three phase supply, approach unity power factor with little harmonic content.", "author_names": [ "Johannes Pforr", "Leslie Hobson" ], "corpus_id": 110594300, "doc_id": "110594300", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Power factor correction using quasi resonant SEPIC converter with three phase input", "venue": "", "year": 1992 }, { "abstract": "The authors present the state of the art pulse density modulation (PDM) type three phase AC/DC power converter with an active voltage clamped resonant DC link (ACRDCL) network and its digital signal processor (DSP) based digital control strategy to achieve a unity power factor correction and sinewave line current shaping. The new operating principle of the zero voltage soft switched three phase AC/DC converter with a ACRDCL and its instantaneous space voltage vector based clamping voltage distributed PDM (modified PDM) strategy to improve its controllability and operating characteristics are described. Performance evaluations of this modified PDM converter are discussed using simulation results as compared with the conventional PDM converter. Experimental results for this switch mode rectifier are shown.<ETX>", "author_names": [ "Kouichi Miyagawa", "Mutsuo Nakaoka", "Yasumasa Ogino", "Yoshishige Murakami", "K Hayashi" ], "corpus_id": 85746445, "doc_id": "85746445", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Space vector controlled soft switching three phase PDM AC/DC converter with unity power factor and sinusoidal line current", "venue": "Proceedings of the 1992 International Conference on Industrial Electronics, Control, Instrumentation, and Automation", "year": 1992 }, { "abstract": "This paper proposes a single phase 3.3 kW onboard battery charger for E Rickshaw with a Single stage Active Power Factor Correction (PFC) Buck Boost Converter topology. Normally, E Rickshaw battery charger is heavy and bulky in dimensions and comprises of a power factor corrector (PFC) and a DC DC converter. A traditional single phase PFC converter has three sensors namely input voltage, input current, and output voltage for measurement. The proposed converter is more compact and more flexible in terms of control and conversion stages a with new Unity Power Factor alongside a combination of a full bridge diode rectifier and a single switch Buck Boost converter by just using one output voltage sensor is presented. The suggested control technique uses only one integrator to compensate for the steady state error and is very simple to implement. The proposed battery charger accomplish Unity Power Factor at variable AC input with a small inductance. To verify the feasibility of the proposed scheme, the proposed battery charger topology is simulated in PSIM. The simulation result indicates a 95% peak efficiency at 220Vac and 93% at a variable input voltage from 170V 280V at 3.3kW. A scaled down lab prototype of 1.5kW is built and experimental results are presented to verify the suitability of the proposed converter.", "author_names": [ "Abhinandan Dixit", "Karan Pande", "Akshay Kumar Rathore", "Rajeev Kumar Singh", "Santanu Kumar Mishra" ], "corpus_id": 218473579, "doc_id": "218473579", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Design Development of On Board DC Fast Chargers for E Rickshaw", "venue": "2019 IEEE Transportation Electrification Conference (ITEC India)", "year": 2019 }, { "abstract": "In this paper, a novel prototype of zero voltage soft switching PWM three phase AC/DC active power converter with a new transformer assisted resonant tank DC link is presented for power factor correction, sinewave line current shaping and output DC voltage regulation. The instantaneous space voltage modulated sinewave current synthesizing scheme of this active rectifier with an instantaneous output DC power feedback loop is implemented by digital signal processor based software and its related hardware. The simulation results of this soft switched active rectifier are illustrated and discussed as compared with the other resonant DC link rectifiers and the hard switched active rectifier.<ETX>", "author_names": [ "Katsutosi Yurugi", "Hideto Yonemori", "Kenji Hayasi", "Mutsuo Nakaoka" ], "corpus_id": 109143045, "doc_id": "109143045", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Next generation space voltage vector ZVT PWM AC DC active power converter with auxiliary transformer assisted resonant DC link", "venue": "Proceedings of 1994 Power Electronics Specialist Conference PESC'94", "year": 1994 } ]

[ { "abstract": "The nonlinear properties of semiconductor lasers and laser amplifiers when subject to optical injection are reviewed and new results are presented for multisection lasers, vertical cavity semiconductor optical amplifiers, and surface emitting lasers. The main underlying material parameters are outlined and the key design approaches are discussed for both edge emitting and vertical cavity devices. An overview of theoretical modeling approaches is discussed and a summary of key experimental results is presented. The practical use of optically injected edge emitting and vertical cavity semiconductor lasers and laser amplifiers is illustrated with examples of applications including, among others, optical logic and chaotic communication.", "author_names": [ "Michael J Adams", "Antonio Hurtado", "Dmitry Labukhin", "Ian D Henning" ], "corpus_id": 44268502, "doc_id": "44268502", "n_citations": 39, "n_key_citations": 0, "score": 1, "title": "Nonlinear semiconductor lasers and amplifiers for all optical information processing.", "venue": "Chaos", "year": 2010 }, { "abstract": "Amplification of ultrashort optical pulses in semiconductor laser amplifiers is shown to result in considerable spectral broadening and distortion as a result of the nonlinear phenomenon of self phase modulation (SPM) The physical mechanism behind SPM is gain saturation, which leads to intensity dependent changes in the refractive index in response to variations in the carrier density. The effect of the shape and the initial frequency chirp of input pulses on the shape and the spectrum of amplified pulses is discussed in detail. Particular attention is paid to the case in which the input pulsewidth is comparable to the carrier lifetime so that the saturated gain has time to recover partially before the trailing edge of the pulse arrives. The experimental results, performed by using picosecond input pulses from a 1.52 mu m mode locked semiconductor laser, are in agreement with the theory. When the amplified pulse is passed through a fiber, it is initially compressed because of the frequency chirp imposed on it by the amplifier. This feature can be used to compensate for fiber dispersion in optical communication systems.", "author_names": [ "Govind P Agrawal", "Nils Anders Olsson" ], "corpus_id": 121699236, "doc_id": "121699236", "n_citations": 1128, "n_key_citations": 97, "score": 0, "title": "Self phase modulation and spectral broadening of optical pulses in semiconductor laser amplifiers", "venue": "", "year": 1989 }, { "abstract": "Following a brief introduction to the applications for wavelength conversion and the different available conversion techniques, the paper gives an in depth analysis of cross gain and cross phase wavelength conversion in semiconductor optical amplifiers. The influence of saturation filtering on the bandwidth of the converters is explained and conditions for conversion at 20 Gb/s or more are identified. The cross gain modulation scheme shows extinction ratio degradation for conversion to longer wavelengths. This can be overcome using cross phase modulation in semiconductor optical amplifiers that are integrated into interferometric structures. The first results for monolithic integrated interferometric wavelength converters are reviewed, and the quality of the converted signals is demonstrated by transmission of 10 Gb/s converted signals over 60 km of nondispersion shifted single mode fiber.", "author_names": [ "Terji Durhuus", "B Mikkelsen", "C Joergensen", "Soeren Lykke Danielsen", "Kristian E Stubkjaer" ], "corpus_id": 109838737, "doc_id": "109838737", "n_citations": 839, "n_key_citations": 37, "score": 0, "title": "All optical wavelength conversion by semiconductor optical amplifiers", "venue": "", "year": 1996 }, { "abstract": "Influences on the semiconductor laser properties of external optical feedback, i.e. return of a portion of the laser output from a reflector external to the laser cavity, have been examined. Experimental observations with a single mode laser is presented with analysis based on a compound cavity laser model, which has been found to explain essential features of the experimental results. In particular, it has been demonstrated that a laser with external feedback can be multistable and show hysteresis phenomena, analogous to those of non linear Fabry Perot resonator. It has also been shown that the dynamic properties of injection lasers are significantly affected by external feedback, depending on interference conditions between returned light and the field inside the laser diode.", "author_names": [ "R S Lang", "Kohroh Kobayashi" ], "corpus_id": 122897739, "doc_id": "122897739", "n_citations": 2214, "n_key_citations": 81, "score": 0, "title": "External optical feedback effects on semiconductor injection laser properties", "venue": "", "year": 1980 }, { "abstract": "Simple two parameter formulas are presented for the functions involved in the amplitude phase and the quadrature nonlinear models of a TWT amplifier, and are shown to fit measured data very well. Also, a closed form expression is derived for the output signal of a TWT amplifier excited by two phase modulated carriers, and an expression containing a single integral is given when more than two such earriers are involved. Finally, a frequencydependent quadrature model is proposed whose parameters are obtainable from single tone measurements.", "author_names": [ "Adel A M Saleh" ], "corpus_id": 110292267, "doc_id": "110292267", "n_citations": 1399, "n_key_citations": 80, "score": 0, "title": "Frequency Independent and Frequency Dependent Nonlinear Models of TWT Amplifiers", "venue": "IEEE Trans. Commun.", "year": 1981 }, { "abstract": "Values up to gamma=7 x 10(6)(W km) for the nonlinear parameter are feasible if silicon on insulator based strip and slot waveguides are properly designed. This is more than three orders of magnitude larger than for state of the art highly nonlinear fibers, and it enables ultrafast all optical signal processing with nonresonant compact devices. At lambda=1.55 microm we provide universal design curves for strip and slot waveguides which are covered with different linear and nonlinear materials, and we calculate the resulting maximum gamma.", "author_names": [ "Christian Koos", "L Jacome", "Christopher G Poulton", "J Leuthold", "Wolfgang Freude" ], "corpus_id": 7069722, "doc_id": "7069722", "n_citations": 364, "n_key_citations": 15, "score": 0, "title": "Nonlinear silicon on insulator waveguides for all optical signal processing.", "venue": "Optics express", "year": 2007 }, { "abstract": "Semiconductor optical amplifiers are useful building blocks for all optical gates as wavelength converters and OTDM demultiplexers. This paper reviews the progress from simple gates using cross gain modulation and four wave mixing to the integrated interferometric gates using cross phase modulation. These gates are very efficient for high speed signal processing and will open up interesting new areas, such as all optical regeneration and high speed all optical logic functions.", "author_names": [ "Kristian Stubkjaer" ], "corpus_id": 53704355, "doc_id": "53704355", "n_citations": 96, "n_key_citations": 6, "score": 0, "title": "Semiconductor Optical Amplifier Based All Optical Gates for High Speed Optical Processing", "venue": "", "year": 2010 }, { "abstract": "This paper provides prospects and current status of quantum dot semiconductor optical amplifiers (SOAs) and their comparison with bulk and quantum well technology, based on our pioneering work covering the proposal of their promising features, subsequent experimental demonstrations, and the design of all optical quantum dot switching modules. The proposed promising features are diverse; high saturation power, high speed amplification up to 160 Gb/s under gain saturation without pattern effect, high speed cross gain modulation up to 160 Gb/s without pattern effect, multiple wavelength processing over broad gain spectra, and symmetric wavelength conversion by four wave mixing. The operation theory of quantum dot SOAs is provided in order to treat various aspects unique to quantum dots such as spatial localization, retarded carrier relaxation, and inhomogeneous and homogeneous broadening. Pattern effect free amplification at 10 40Gb/s, wavelength conversion by the cross gain modulation at 10 40Gb/s, and symmetric wavelength conversion by four wave mixing are experimentally demonstrated in 1.3 micron InGaAs/GaAs quantum dot SOAs. All optical quantum dot switching modules are proposed, which we expect to work in the next generation flexible all optical photonic networks.", "author_names": [ "Mitsuru Sugawara", "Tomoyuki Akiyama", "Nobuaki Hatori", "Yoshiaki Nakata", "Koji Otsubo", "Hiroji Ebe" ], "corpus_id": 119846236, "doc_id": "119846236", "n_citations": 154, "n_key_citations": 24, "score": 0, "title": "Quantum dot semiconductor optical amplifiers", "venue": "SPIE/OSA/IEEE Asia Communications and Photonics", "year": 2002 }, { "abstract": "Photonic circuits, in which beams of light redirect the flow of other beams of light, are a long standing goal for developing highly integrated optical communication components. Furthermore, it is highly desirable to use silicon the dominant material in the microelectronic industry as the platform for such circuits. Photonic structures that bend, split, couple and filter light have recently been demonstrated in silicon, but the flow of light in these structures is predetermined and cannot be readily modulated during operation. All optical switches and modulators have been demonstrated with III V compound semiconductors, but achieving the same in silicon is challenging owing to its relatively weak nonlinear optical properties. Indeed, all optical switching in silicon has only been achieved by using extremely high powers in large or non planar structures, where the modulated light is propagating out of plane. Such high powers, large dimensions and non planar geometries are inappropriate for effective on chip integration. Here we present the experimental demonstration of fast all optical switching on silicon using highly light confining structures to enhance the sensitivity of light to small changes in refractive index. The transmission of the structure can be modulated by up to 94% in less than 500 ps using light pulses with energies as low as 25 pJ. These results confirm the recent theoretical prediction of efficient optical switching in silicon using resonant structures.", "author_names": [ "Vilson R Almeida", "Carlos Angulo Barrios", "Roberto R Panepucci", "Michal Lipson" ], "corpus_id": 4404067, "doc_id": "4404067", "n_citations": 1364, "n_key_citations": 28, "score": 0, "title": "All optical control of light on a silicon chip", "venue": "Nature", "year": 2004 }, { "abstract": "Basic Concepts Recombination Mechanisms and Gain Epitaxial Growth and Amplifier Designs Low Reflectivity Facet Designs Amplifier Rate Equations and Operating Characteristics Photonic Integrated Circuit Using Amplifiers Functional Properties and Applications Optical Logic Operations Optical Logic Circuits", "author_names": [ "Niloy K Dutta", "Qiang Wang" ], "corpus_id": 109106108, "doc_id": "109106108", "n_citations": 124, "n_key_citations": 12, "score": 0, "title": "Semiconductor optical amplifiers", "venue": "", "year": 2006 } ]

[ { "abstract": "Abstract Resistive random access memory (RRAM) devices with a nickel top electrode form controllable metal nanofilaments and have robust resistive switching performance. We investigate the Ni/HfO 2 /SiO x /n Si RRAM structure, which forms a Ni rich defect in the silicon underneath the Ni nanofilament in the dielectric layers after a SET process. The formation of these defects may affect the retention of the devices, so we applied a detailed Finite Element Method and Kinetic Monte Carlo approach to simulate the Ni rich defect evolution under different compliance current settings. We confirm that the chemical composition of the defects is metallic NiSi 2 and that their size is determined by the compliance current. These simulation results are supported by in situ STM like experiments inside a transmission electron microscope (TEM) NiSi 2 defects are shaped as truncated square pyramids, and we show that this is due to the low activation energy of Ni migration along the (111) crystal plane of Si. Our results demonstrate that electromigration is the main driving force for Ni migration initially, after which thermal migration and especially stress migration become the dominant mechanism. This work gives a fascinating example of an as grown metal insulator semiconductor (MIS) system that can be controllably converted to a metal insulator metal (MIM) configuration for down scaled RRAM operation.", "author_names": [ "Sen Mei", "Michel Bosman", "Nagarajan Raghavan", "Xing Wu", "Kin Leong Pey" ], "corpus_id": 29299471, "doc_id": "29299471", "n_citations": 11, "n_key_citations": 1, "score": 0, "title": "Compliance current dominates evolution of NiSi2 defect size in Ni/dielectric/Si RRAM devices", "venue": "Microelectron. Reliab.", "year": 2016 }, { "abstract": "Spinel ferrites are an important class of compounds which have a variety of electrical, magnetic, and catalytic applications. Neodymium doped cobalt ferrites with composition CoNdxFe2 xO4 where x is 0.00 0.20 were synthesized by a sol gel method. A sol gel method was preferred because it has good control over stoichiometry, crystallite size, and particle size distribution. An X ray diffraction (XRD) technique was used for structural analysis, and a crystal structure was found to be spinel for all samples. Fourier transform infrared spectroscopy (FTIR) of the samples was also performed for structural information. DC resistivity has been studied, as a function of temperature, by using a two probe method. It showed direct dependence on temperature and inverse dependence on the concentration of Nd dopant. I V characteristics of samples at room temperature were analyzed. The non linear I V curves showed a non ohmic behavior. When voltage was reversed, it did not follow the same values but showed a hysteresis loop type trend. This confirms the presence of resistive switching effect in this voltage range at room temperature. The studied material is a potential candidate for resistive random access memory application.", "author_names": [ "S Abbas", "", "Mohammad Saeed", "A Munir", "Muhammad Anis-Ur-Rehman" ], "corpus_id": 126062814, "doc_id": "126062814", "n_citations": 1, "n_key_citations": 0, "score": 0, "title": "Study of Transport Properties in Co (Fe Nd) Ferrite Nanoparticles for RRAM Applications", "venue": "", "year": 2017 }, { "abstract": "We report the first demonstration of in situ electrical biasing and resistive switching of TiO2 based RRAM while observing oxygen vacancy migration under the TEM. Specifically, repeated extension and retraction of Wadsley defects due to the migration of oxygen vacancies was observed to be concurrent with the SET and RESET processes (respectively) in the hysteretic I V behavior of single crystal TiO2 devices. Additionally, structural evolution within a 20 nm size grain was observed during SET processes in ALD grown TiO2 devices using STEM HAADF imaging.", "author_names": [ "Jonghan Kwon", "Yoosuf N Picard", "Marek Skowronski", "Abhishek A Sharma", "James A Bain" ], "corpus_id": 29777719, "doc_id": "29777719", "n_citations": 3, "n_key_citations": 1, "score": 0, "title": "In situ biasing TEM investigation of resistive switching events in TiO2 based RRAM", "venue": "2014 IEEE International Reliability Physics Symposium", "year": 2014 }, { "abstract": "Two dimensional materials are gaining more and more attention in the field of electronic devices because of their unique advantages, such as high crystalline quality and clean and flat contact planes; compared to traditional materials, the use of two dimensional materials as the working layer of a resistive random access memory (RRAM) has the potential to further reduce the device size and enhance its performance. Herein, a black phosphorus (BP) single crystal flake passivated by hafnium oxide is used as the working layer for an RRAM. The devices show a switching on/off ratio of 102 in more than 100 cycles, and others can even be as high as 106. We speculated the working mechanism of the BP RRAM based on the results of serial experiments and transport analysis.", "author_names": [ "Xiaoyuan Yan", "Xueting Wang", "Boran Xing", "Yingxia Yu", "Jiadong Yao", "Xinyue Niu", "Mengge Li", "Jian Sha", "Yewu Wang" ], "corpus_id": 225527487, "doc_id": "225527487", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Resistive memory based on single crystalline black phosphorus flake/HfOx structure", "venue": "", "year": 2020 }, { "abstract": "Resistive random access memory (RRAM) utilizes the resistive switching behavior to store information. Compared to charge based memory devices, the merits of RRAM devices include multi bit capability, smaller cell size, and energy per bit ~fJ/bit) In this chapter, we review different perovskite material based resistive random access memories (RRAMs) We first introduce the history of RRAM development and operational mechanism of conduction, followed by a review of two types of materials with perovskite crystal structure. One is conventional perovskite oxides (PCMO, a LCMO, etc. and the other is perovskite halides (organic inorganic hybrid perovskites and inorganic perovskites) that have recently emerged as novel materials in optoelectronic fields. Our goal is to give a comprehensive review of perovskite based RRAM materials that can be used for neuromorphic computing and to help further ongoing development in the field.", "author_names": [ "Jiaqi Zhang", "Wubo Li" ], "corpus_id": 204305992, "doc_id": "204305992", "n_citations": 0, "n_key_citations": 0, "score": 1, "title": "Perovskite Materials for Resistive Random Access Memories", "venue": "", "year": 2019 }, { "abstract": "Abstract Multiferroic B i F e O 3 (BFO) and B i 0.97 Y 0.03 F e 0.95 S c 0.05 O 3 (BYFSO) films were fabricated on FTO coated glass substrate using sol gel spin coating technique. Y Sc co doping induces the structural distortion without changing the crystal structure (rhombohedral: R3c) of BFO. The electrical and magnetic properties of co doped film may tuned due to increase in grain and particles size. The high dielectric constant e r 290 and low loss t a n d 0.084 indicates the improved insulating properties in BYFSO film. Increase in oxygen vacancy concentration in BYFSO film is explained with leakage current density, which follows Ohmic SCLC conduction mechanism. Switching of 180 0 domains into non 180 0 (maximum 71 0 and 109 0 type) ensures improved ferrolectric and piezoelectric properties in BYFSO film. The magnetic properties enhance significantly with saturation magnetization M s remanent magnetization M r are 9.45 e m u c m 3 6.154 e m u c m 3 respectively at coercive H c field of 0.822 kOe. Room temperature multiferroic BYFSO film with improved insulating and magnetic properties may be useful for non volatile RRAM memory application.", "author_names": [ "Ashis Kumar Jena", "J Arout Chelvane", "J Mohanty" ], "corpus_id": 199881650, "doc_id": "199881650", "n_citations": 6, "n_key_citations": 0, "score": 0, "title": "Simultaneous improvement of piezoelectric and magnetic properties in diamagnetic ion modified BiFeO3 film", "venue": "Journal of Alloys and Compounds", "year": 2019 }, { "abstract": "Formation of metal rich conductive filaments and their rearrangements determine the switching characteristics in HfO2 based resistive random access memory (RRAM) devices. The initiation of a filament formation process may occur either via aggregation of pre existing vacancies randomly distributed in the oxide or via generation of new oxygen vacancies close to the pre existing ones. We evaluate the feasibility of vacancy aggregation processes by calculating the structures and binding energies of oxygen vacancy aggregates consisting of 2, 3 and 4 vacancies in bulk monoclinic (m) HfO2 using density functional theory (DFT) We demonstrate that formation of neutral oxygen vacancy aggregates is accompanied by small energy gain, which depends on the size and shape of the aggregate. In the most strongly bound configurations, vacancies are unscreened by Hf cations and form voids within the crystal, with the larger aggregates having larger binding energy per vacancy 0.11 to 0.18 eV) The negatively charged di vacancy was found to have similar binding energies to the neutral one, while the positively charged di vacancy was found to be unstable. Thus aggregation process of either neutral or negatively charged oxygen vacancies is energetically feasible.", "author_names": [ "Samuel R Bradley", "Gennadi Bersuker", "Alexander L Shluger" ], "corpus_id": 2803389, "doc_id": "2803389", "n_citations": 31, "n_key_citations": 2, "score": 0, "title": "Modelling of oxygen vacancy aggregates in monoclinic HfO2: can they contribute to conductive filament formation?", "venue": "Journal of physics. Condensed matter an Institute of Physics journal", "year": 2015 }, { "abstract": "DOI: 10.1002/aelm.201700608 gap structure cannot be able to integrate in vertical direction. In 2008, Salahuddin et al.[8] proposed negative capacitance transistor using the polarization change induced abrupt switch with steep slope (Figure 1b) But at present, the integration of the ferroelectric materials with smaller hysteresis window is remained to be studied. A critical question that can be considered is if there is another mechanism that can be applied to build novel transistor with steep slope. Here, we propose a new kind of steep slope transistor named \"filament transistor\" with SS down to sub 10 mV dec 1. The abrupt filament set/reset induced by gate can enable the abrupt current change with steep slope. Conventional resistive random access memory (RRAM) is usually a simply two terminal device with a metal oxide layer sandwiched by two metal electrodes. Due to the high carrier densities (above 1020 cm 3) of metal electrode, the gate E field is screened by the bottom electrode without any gate tunability. In this work, the bilayer grapheme (BLG) is used as bottom electrode with low carrier densities[20] (around 1012 cm 2) connecting to the source terminal, which can let the gate E field effective penetrate through the graphene. The channel material above graphene is AlOx with 5 nm thickness in vertical direction, so that the gate E field can effectively control the filament formation/rupture inside the AlOx. The top electrode Al above the AlOx is connected to drain terminal. The schematic device structure and operation mechanism for the filament transistor at on state and off state are shown in Figure 1c. At positive gate voltage condition, the positive E field from gate can attract oxygen ions moving toward the bottom surface. In this case, the effective oxygen ions density is low, which is named as the \"oxygen ions depleted\" state. As a result, it requires higher set voltage at drain terminal. When negative gate voltage is applied, the negative E filed from gate can repel the oxygen ions to top electrode, which is named as \"oxygen ions accumulated\" state. The \"oxygen ions accumulated\" state can promote the filament formation, which means a lower set voltage at drain terminal can be sufficient for the filament formation. The device was fabricated as following: the single crystal bilayer graphene was obtained via chemical vapor deposition (CVD) method or mechanical exfoliation. For CVD method, first one single layer graphene (SLG) with 50 mm size was grown and then through the center defect, another SLG was grown followed by oxygen patterning. The BLG was transferred/exfoliated to a SiO2 (300 nm)/Si substrate with a marker. This was There is a growing trend of developing steep slope transistors with subthreshold swing (SS) below 60 mV dec 1. At present, there are mainly three kinds of steep slope transistors: tunneling transistor, negative capacitance transistor, and nano electromechanical relay. Here, a new kind of steep slope transistor named \"filament transistor\" is proposed with SS down to sub 10 mV dec 1. Due to the gate E filed can penetrate through the graphene, the gate can effectively control the filament formation/rupture inside the 5 nm AlOx with very steep slope. In reverse sweep, the gate can induce the filament formation with SS down to 4.6 mV dec 1. In forward sweep, the gate can break the filament with SS down to 12.2 mV dec 1. Taking the advantages of nanofilament, the filament transistor holds a great potential to scaling down to 5 nm without performance changing.", "author_names": [ "He Tian", "Xuefeng Wang", "Haiming Zhao", "Wentian Mi", "Yi Yang", "Po-Wen Chiu", "Tian-ling Ren" ], "corpus_id": 51823384, "doc_id": "51823384", "n_citations": 10, "n_key_citations": 0, "score": 0, "title": "A Graphene Based Filament Transistor with Sub 10 mVdec 1 Subthreshold Swing", "venue": "", "year": 2018 }, { "abstract": "Resistance random access memory, short RRAM, which employs two or more resistive states of a material for data storage, has attracted considerable attention as a highly scalable future non volatile memory concept. 1 2 These memory cells that can also be described as so called memristors are particularly interesting when multilevel resistance values or even analogue values should be stored and processed. 3 5 A large variety of binary and ternary oxides exhibit resistive switching phenomena, however, the details of the complex microscopic mechanisms are rarely understood and depend strongly on the specifi c material combination. In the search for promising oxide materials for future non volatile memories, special attention has to be paid to their scaling capabilities. The issue of scaling is strongly linked to the question of, whether the switching current is distributed homogeneously across the device area or localized to one or a few conducting fi laments. While in the former case the scaling limit will be connected to the minimum device area, that guarantees suffi cient switching currents for a reliable circuit operation, in the latter case, scaling might suffer from too large fi lament dimensions or their insuffi cient density and regularity within the material. Complex transition metal oxides, e.g. manganites, 6 9 titanates and zirconates, 10 11 usually exhibit different resistance states at opposite polarities of electrical stimulation. It has become widely accepted that this so called bipolar resistive switching is connected with a voltage driven oxygen vacancy movement and a resulting redox process. 12 Both, fi lamentary as well as homogenous switching has been reported in the literature. For thermally reduced SrTiO 3 single crystals it has been clearly demonstrated by conductive tip atomic force microscopy (conductive AFM) that resistive switching at free surfaces occurs along conducting fi laments which can be identifi ed with the exits of dislocations. 13 For crystalline SrTiO 3 thin fi lm samples as well as amorphous TiO 2 capped between macroscopic electrodes, the indispensable electroforming process results in the formation of a single m m size fi lament. 14 18", "author_names": [ "Ruth Muenstermann", "Tobias Menke", "Regina Dittmann", "Rainer Waser" ], "corpus_id": 205237736, "doc_id": "205237736", "n_citations": 289, "n_key_citations": 3, "score": 0, "title": "Coexistence of filamentary and homogeneous resistive switching in Fe doped SrTiO3 thin film memristive devices.", "venue": "Advanced materials", "year": 2010 }, { "abstract": "The antimony atom in the crystal structure of [ammonium (rram cyclohexane 1,2diaminetetraacetato)antimonate(III) [ammonium chloride] which is (4O 2N) chelated by the diaminetetracarboxylato group [Sb 0= 2.216(5) 2.433(6) Sb N 2.325(5) A] exists in a ps pentagonal bipyramidal geometry in which the lone pair occupies an equatorial site. The (cyclohexane 1,2diaminetetraacetato)antimonate(III) anion lies on a two fold axis, and is linked to two adjacent anions through the carboxyl oxygen atom that forms the longer Sb 0 bond to result in a zig zag chain. If these weak interactions [Sb O 3.153(6) A; O Sbl 0 3 108.1(2)deg] are regarded as formal bonds, the eightcoordinate antimony atom shows distorted dodecahedral coordination. Lone pair stereochemistry is discussed quantitatively in relation to the structures of the previously reported polyaminocarboxylate complexes of antimony(III) and bismuth(III) Crystal data: CuFLeN tOgClSb, FW 535.59, monoclinic, C2/c, a 12.534(2) b 23.570(3) c 8.708(1) A, b 133.22(1)deg, Dx.ray 1.898 g cm\" m 13.77 mm\" F(000) 1080 for Z 4. Introduction The VSEPR model [1] incorrectly predicts the molecular geometries for a number of the heavier congeners of subvalent fourth group metal compounds owing to the stereochemical inactivity of the lone pair of electrons [2] Stereochemical inertness is also noted for some fifth group metal compounds; in particular, the bismuth(IIl) complexes of polyaminocarboxylates display no stereochemical activity [3] as seen from the cubic environment found in the di(nitrilotriacetato)bismuthate(III) trianion [4] Owing to the smaller size of the antimony atom compared with the bismuth atom, lone pair effects dominate, these deforming the polyhedra of antimony(III) compounds. When a diaminepolycarboxylato ligand chelates in a hexadentate (4O 2N) manner, the resulting polyhedron assumes a distorted ps pentagonal bipyramid and the lone pair will be either axially or equatorially positioned [5] The triaminepolycarboxylato ligand is able to give rise to ps pentagonal bipyramidal as well as the ps monocapped square antiprismatic geometries [6] For such antimony(III) complexes, however, the correct geometry should assigned only when all weaker or secondary interactions have been included [7] these interactions are typically intermediate between normal covalent bond lengths and van der Waals distances. The (cyclohexane 1,2diaminetetraacetato)antimonate(III) anion has been characterized as its hydrated sodium salt; the three water molecules engage in extensive hydrogen bonding, and appear to be necessary to consolidate the structure [8] In the present study, the sodium cation is replaced by the ammonium counterion, but the synthesis gave the ammonium antimonate(III) as a 1/1 complex with ammonium chloride (Scheme I) Its crystal structure and the polyhedral distortion are discussed in terms of the displacement of the antimony atom from the 'best' centroid of the coordination polyhedron [9] Experimental Sodium antimony 1 tartarate (3.5 g, 5.7 mmol) prepared by treating antimony oxide with racemic tartaric acid and sodium hydroxide [10] was dissolved in water (25 mL) and the solution was acidified with concentrated hydrochloric acid (2 mL) The filtered solution was added dropwise to a soltuion of iram cyclohexane 1,2 diaminetetraacetic acid (2.0 g, 5.7 mmol) dissolved in a mixture of water (128 mL) and IN ammonia (22 mL) The mixture was heated under reflux for 5 h. The solution was concentrated to about 5 mL; the colorless crystals that precipitated have no definite melting point, but begin to decompose", "author_names": [ "Shengzhi Hu", "Yizhi Fu", "Lisbeth E Toennessen,", "Ruven L Davidovich", "Seik Weng Ng," ], "corpus_id": 98551905, "doc_id": "98551905", "n_citations": 3, "n_key_citations": 0, "score": 0, "title": "LONE PAIR STEREOCHEMISTRY OF ANTIMONY(III) POLYAMINOCARBOXYLATES. CRYSTAL STRUCTURE OF [AMMONIUM (trans CYCLOHEXANE 1,2 DIAMINETETRAACETATO) ANTIMONATE][AMMONIUM CHLORIDE]", "venue": "", "year": 1998 } ]

[ { "abstract": "A renewable energy source plays an important role in electricity generation. Various renewable energy sources like wind, solar, geothermal, ocean thermal, and biomass can be used for generation of electricity and for meeting our daily energy needs. Energy from the sun is the best option for electricity generation as it is available everywhere and is free to harness. On an average the sunshine hour in India is about 6hrs annually also the sun shine shines in India for about 9 months in a year. Electricity from the sun can be generated through the solar photovoltaic modules (SPV) The SPV comes in various power output to meet the load requirement [1] Maximization of power from a solar photo voltaic module (SPV) is of special interest as the efficiency of the SPV module is very low. A peak power tracker and DC DC Boost Converter is used for Extracting the maximum power from the SPV module. And simulation in PSIM software and hardware result is compare and solar panel maximum efficiencies is increase nearby 85% using dither routine algorithm method use. Keywords PV module, Battery, Grid,Maximum Power Point Tracking( MPPT) module, Inverter, PSIM, Boost converter. Introduction Renewable energy sources play an important role in electricity generation. Various renewable energy sources like wind, solar, geothermal, ocean thermal, and biomass can be used for generation of electricity and for meeting our daily energy needs. Energy from the sun is the best option for electricity generation as it is available everywhere and is free to harness. On an average the sunshine hour in India is about 6hrs annually also the sun shine shines in India for about 9 months in a year. A worldwide concern for future access to affordable, sustainable energy is driving the development of more efficient solar power generation [2] In any photovoltaic (PV) based system, the master controller is a critical component responsible for the control of electricity flow between the module, battery, loads, grid. The proposed for maximum power point tracking, boost converter, battery charging, and load control. The main elements of maximum power point tracking system for dc dc boost converter, battery charging circuit, PIC controller which selects energy sources to continue supply the load. Using the simulation software PSIM proposed boost converter topology with predictive control has been chosen. The final simulation of dc dc boost converter has been done, which was made in PSIM. It is shown that the output voltage (30 Vdc) to supply the load and, to charge the battery if solar output power is greater than the load power. The proposed control algorithm including the whole system control is implemented on a low cost, microcontroller PIC16F690.solar system efficiency increase near 90% Simulation of DC dc boost converter in psim The boost converter, also known as the step up converter, is another switching converter that has the same components as the buck converter, but this converter produces an output voltage greater than the source. The ideal boost converter has the five basic components, namely a power semiconductor switch, a diode, an inductor, a capacitor and a PWM controller. The placement of the inductor, the switch and diode in the boost converter is different from that of the buck converter, which is shown in the Fig.1. Fig.1 Basic of DC DC Boost Converter Circuit Diagram [4] Simulation of Open Loop Dc Dc Boost Converter Result The simulation of DC DC Boost converter is shown in the Fig.2 Fig.2 Simulation of PV with Open Loop DC DC Boost Converter International Journal of Research and Engineering Volume 2, Issue 2 7 http:/www.ijre.org ISSN 2348 7852 (Print) ISSN 2348 7860 (Online) Fig.3 (a)(b) and (c) shows that the output waveform of open loop DC DC Boost converter of solar panel output power 25W, output current 0.75A and output voltage of 30V respectively. a. Result of Open Loop DC DC Boost Converter of Solar Panel Power 25W (b) (C) Fig.3. (b)Result of Open Loop DC DC Boost Converter for Output Current 0.75A, (C)Result of Open Loop DC DC Boost Converter output voltage 30V (a) (b) Fig.4 (a) Switching Wave of MOSFET Using Open Loop DC DC Boost Converter, (b) Voltage across Inductor Wave of Open Loop DC DC Boost Converter Fig.4 (a) and (b) shows that the switching wave of MOSFET Using Open Loop DC DC Boost Converter and Voltage across Inductor Wave of Open Loop DC DC Boost Converter respectively [6] Hardware circuit diagram of boost converter A circuit diagram is required to implementation of hardware model, which is shown in the Fig.5 [5] Fig.5 Circuit Diagram of Open Loop DC DC Boost Converter International Journal of Research and Engineering Volume 2, Issue 2 8 http:/www.ijre.org ISSN 2348 7852 (Print) ISSN 2348 7860 (Online) Based on the hardware circuit diagram the model could be prepared, which is shown in the Fig.6. Fig.6 Snapshot of Open Loop DC DC Boost Converter Fig.7 shows that the hardware result of boost converter with MPPT. Fig.7 3% Input duty Cycle and o/p voltage 11.5V waveform Fig.8 32% Input duty cycle and O/P voltage 28V waveform Fig.9 Voltage across Inductor Wave of DC DC Boost Converter Hardware Result Table No.1 shows that the testing result of hardware with solar panel. Which is graphically represented in the Fig.12 and Fig.13 identically. TABLE NO.1 No Of Readi ng Solar Panel O/P (I0) Solar Panel O.C.V(V) Maximum Power(W) Duty Cycle", "author_names": [ "Hassan Abbas Khan", "S K Khatik", "Sulbha Amlathe", "Taruna Jain", "Anil Prakseh" ], "corpus_id": 4490320, "doc_id": "4490320", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "DIMINISHING THE REQUIREMENT OF POWER USING PLC AND SCADA SYSTEMS IN POWER GRID SYSTEM", "venue": "", "year": 2015 }, { "abstract": "In this paper we have developed a SCADA system for monitoring accessing the performance of parameter such as voltage, current, humidity on real time basis. For this we have used the infrastructure of the existing industrial network, which is based on plc, Supervisory Control and Data Acquisition (SCADA) is a field of constant development and research. This project investigates on creating an extremely low cost device which can be adapted to many different SCADA applications via some very basic programming, and plugging in the relevant peripherals. Much of the price in some expensive SCADA applications is a result of using specialized communication infrastructure. The application of infrastructure, in the proposed scheme the cost will come down. Additionally the generic nature of the device will be assured. A SCADA deals with the creation of an inexpensive, yet adaptable and easy to use SCADA device and infrastructure using the industrial network, in particular. The hardware components making up the device are relatively unsophisticated, yet the custom written software makes it re programmable over the air, and able to provide a given SCADA application with the ability to send and receive control and data signals at any non predetermined time. From the SCADA system which is proposed in setup the battery voltage of 12v could be sufficiently recorded from remote location. The properly designed SCADA system saves time and money by eliminating the need of service personal to visit each site for inspection, data collection /logging or make adjustments. Main concept of our paper is data acquisition controlling by using SCADA software and PLC. Here PLC is a medium between electrical system Personal Computer for SCADA to take input and output bits. Automating electrical distributions systems by implementing a supervisory control and data acquisition (SCADA) system is the one of the most cost effective solutions for improving reliability, increasing utilization, increasing efficiency and saving costs. Nowadays consumer requires more reliable efficient power supply. So we can use automation systems as per the consumer", "author_names": [ "Narayan Lal Purohit" ], "corpus_id": 25915490, "doc_id": "25915490", "n_citations": 6, "n_key_citations": 0, "score": 1, "title": "Data Acquisition of Solar Power Plant Using Scada System", "venue": "", "year": 2015 }, { "abstract": "Automation means Delegation of human control to machine. A PLC (Programmable Logic Controller) is a device that was invented to replace the necessary sequential relay circuits for machine control. A SCADA (Supervisory Control Data Acquisition System) is used to control the process where person cannot go or stay for longer period. The aim of tis paper is to provide information about hoelectricity can be generated from Renewable sources how its transmission done usin automation system. Renewable Energy consists of energy generated from natural and unlimited sources, which include wind, solar, biomass and hydroelectricity. Programmable logic controllers (PLC) can be used for control automation in Distribution of Energy. The main reason for this is cost effectiveness. Various functions and controls can be achieved by programming the PLC. They can be used for full plant automation including governing of autooperation includes speed control, load control, excitation control, and level control automatic start/stop sequencing, gate control, start/stop of auxiliary systems, and protection requirement etc. Functions other than control like continuous monitoring, data recording, instrumentation and protections can also be performed. For remote operation, communication with PLC can be performed. For continuous monitoring purpose, a personal computer can be interfaced with PLC and continuous data can be recorded regularly. In this paper I used different methods for generation of electricity like wind, PV (photovoltaic) hydro, biogas distributed using PLC controlling using SCADA. Key TermsPLC (programmable Logic Controller) SCADA (Supervisory Control Data Acquisition System) PV (Photovoltaic)", "author_names": [ "Rahul Deshmukh", "Pankaj H Zope", "Shekhar R Suralkar", "T S S B" ], "corpus_id": 212563958, "doc_id": "212563958", "n_citations": 2, "n_key_citations": 0, "score": 0, "title": "Generation of Electricity by Renewable Energy Sources Transmission of Energy Production Units using PLC SCADA", "venue": "", "year": 2012 }, { "abstract": "The system mainly use wall mounted gas boiler and give priority in use of solar energy in order to maximize the utilization of solar resources. The excess heat will be added to domestic water when the heat for floor radiant heating is enough. The PLC of Siemens is set as slave computer in the monitoring system and it is used to collect thermal parameters such as temperature, flow rate, etc. by temperature sensors, pressure sensors and flow rate sensors. WinCC is set as the host computer to monitor the operating conditions of the entire system. Real time tracing, monitoring and alarming function can be achieved based on the SQL database, which has realized archive management of the date. The system has been debugged after the whole experiment platform is completed, and the running state of the system shows that this system has high reliability and good stability.", "author_names": [ "Xu Hui", "Cai Yingling", "Yang Huizhen" ], "corpus_id": 115006742, "doc_id": "115006742", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "THE DEVELOPMENT OF SOLAR ENERGY GAS COUPLING SYSTEM (SCADA) IN BUILDINGS", "venue": "", "year": 2015 }, { "abstract": "This project is focusing on the designing and constructing an attractive prototype solar power plant for teaching and learning kit. The aim of this project is to give people especially student the overview of operations of solar power plant in generating electricity in attractive way. Through this approach, people will be more interested to learn about the operation of solar power plant and at the same time this renewable energy can be implemented widely in this country. This prototype will be implemented with Supervisory Control and Data Acquisition (SCADA) system to monitor and control the solar prototype plant. User or operator can observe the actual operation of solar power plant in graphical method through the PC. DC and AC load switching is implemented through SCADA system. In this project, programmable logic controller (PLC) will be used to interface between hardware parts and software parts. Solar prototype plant is basically consisting of solar photovoltaic panel, charge controller, rechargeable battery, power inverter, SCADA software and PLC.", "author_names": [ "Muhammad Nashriq", "Mohd Haris" ], "corpus_id": 108879205, "doc_id": "108879205", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Renewable Energy (Solar Power) Mini Prototype Plant With Scada System", "venue": "", "year": 2010 }, { "abstract": "The former Research Institute for Sustainable Energy (RISE) testing laboratory was originally a facility for measuring, monitoring and testing a variety of renewable energy systems. The RISE facility was independent of the School of Engineering and Energy, but has recently been taken over by the School as the Engineering and Energy Laboratory. Many of the systems associated with the laboratory have not been operated for a number of years and the condition of these systems, and the equipment that is associated with them, is not known. Personnel involved with the former RISE facility have since left Murdoch taking with them their knowledge of the facility. This project was primarily concerned with re commissioning these systems and developing an operational knowledge of the SCADA based control system. Areas to be covered in particular were: connections to the grid from PV arrays and wind turbines PLC system and software inverters, solar array simulator, environmental chamber and other peripheral equipment power supplies such as the diesel generator, motor generator set and battery banks 3 phase permanently connected power monitors AC and DC electrical systems Initial inspections of the electrical systems showed that two key components of the facility were found to be defective and would need to be rectified if the facility was to function properly. These components were the diesel generator which provided electricity totally independent of the grid for testing purposes, and a fault on the PLC which was affecting the operation of the electrical systems. Also several main pieces of equipment had since been removed from the facility; most notably of these being the battery banks, main test inverter and the DC supply from the wind turbines located in what is now known as the Renewable Energy Outdoor Test Area (ROTA) Several pieces of equipment required for the operation of the diesel generator would also require attention such as the fuel tank and starting battery. Approval was granted for the alternator to be repaired and placed back into service. Approval was also granted for the purchase of a replacement analogue input card to rectify the fault with the PLC. In addition to this another requirement of the project was to develop a system so that the laboratory could be used as a training facility for future students. A procedure was developed so that an electrical system consisting of actual real components; a source, a transmission and distribution system and a load could be simulated. Software was also developed using National Instruments LabVIEW software to monitor and record various power parameters from the system. The system is referred to as the \"Small Electrical Distribution System\" As an aside to this a program has been developed that monitors and records voltage, current and power that is being produced by the Real PV Array located on the roof of the Energy and Engineering Laboratory building. For someone who is unfamiliar with the setup of the electrical systems that make up the Energy and Engineering Laboratory a simplified block diagram of the Main AC switchboard has been produced. Schedules have been included of all socket inlets and outlets, main AC and communications cables and the Main AC Switchboard nomenclature. The diesel generator is nearly ready to be re commissioned after approximately 5 years of non use. Procedures have been developed so that a user can configure the Main AC switchboard so that the \"Small Electrical Distribution System\" can be operated safely and measurements obtained and analysed. The main goal of the project was to get the diesel generator operating; therefore this report is focused on the equipment associated with the diesel generator. The equipment focused on was the diesel generator itself, the Main AC Switchboard, the Load Bank and the PLC system. Systems such as the Main DC switchboard and Solar Array Simulator were not covered in as much detail as they are not required for the \"Small Electrical Distribution System\"", "author_names": [ "Christopher Woodard" ], "corpus_id": 106561990, "doc_id": "106561990", "n_citations": 2, "n_key_citations": 1, "score": 0, "title": "Rise SCADA and electrical system: A report pertaining to the condition and serviceability of the electrical and SCADA systems of the former RISE facility", "venue": "", "year": 2013 }, { "abstract": "This paper presents the implementation of Web SCADA on the hybrid wind PV power system. Both the electrical paramaters such as current, voltage, power and the environment parameters such as wind speed, solar irradiation, and PV temperature are monitored remotely via Internet using a web browser. The SCADA system allows the user to control the hybrid power system remotely. The low cost sensor systems, RTUs and PLC are developed for implementing the SCADA system. The IntegraXor SCADA is employed as the Web SCADA software. It provides the easy way for developing the Web based SCADA application. The experimental results show that the Web SCADA works properly in the monitoring and controlling the hybrid power system. The developed sensor systems provides the average error of 2.87% The developed RTUs are able to acquire the sensor data and communicate with the SCADA server in real time.", "author_names": [ "Aryuanto Soetedjo", "Yusuf Ismail Nakhoda", "Abraham Lomi", "Farhan Farhan" ], "corpus_id": 73628294, "doc_id": "73628294", "n_citations": 7, "n_key_citations": 0, "score": 0, "title": "Web SCADA for Monitoring and Controlling Hybrid Wind PV Power System", "venue": "", "year": 2014 }, { "abstract": "Abstract The present study is about the design and implementation of renewable energy by means of solar, small hydro and stair climbing power systems based on Programmable Logic Controller (PLC) and Supervisory Control and Data Acquisition (SCADA) technology. The PLC technology correlates the hybrid system process parameters for the On Grid and Off Grid conditions. The hardware and the software implemented in this proposed system have been put forward to demonstrate the validity and feasibility of the approach. The test results obtained from this renewable energy system prove high accuracy and reliability in regulation while compared with the individual power unit. This renewable Hybrid Power Generation System (HPGS) was studied in real time and it proves to be a versatile and effective gadget for remote area and also for domestic applications.", "author_names": [ "G Madhan", "Dr S Muruganand" ], "corpus_id": 49673411, "doc_id": "49673411", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design and Implementation of a PLC Based Real Time Monitoring and Control System for a Hybrid Renewable Energy System", "venue": "", "year": 2015 }, { "abstract": "Non renewable energy is a relatively short term energy source; consequently, the uses of alternative sources such as solar energy are becoming more wide spread. To make solar energy more viable, the efficiency of solar array systems must be maximized. A feasible approach to maximizing the efficiency of solar array systems is sun tracking.PV modules are devices that cleanly convert sunlight into electricity and offer a practical solution to the problem of power generation in remote areas. The Sun Tracking system using PLC designed offers a reliable and affordable method of aligning a PV module with the sun in order to maximize its energy output.Design of Sun Tracking system using PLC is a hybrid hardware/software prototype, and consists of SCADA system which automatically provides best alignment of PV panel with the sun, to get maximum output (electricity) with monitoring the system by controlling the movement with Programmable Logic Controller (PLC) and minimizing the loss of energy that is applied for the control system.By applying the proposed technique it is expected that the efficiency of the PV plant will maximize.", "author_names": [ "Berhanu Gizaw" ], "corpus_id": 114362622, "doc_id": "114362622", "n_citations": 0, "n_key_citations": 0, "score": 0, "title": "Design Simulation Of Sun Tracking System Using PLC", "venue": "", "year": 2014 }, { "abstract": "Development of a solar powered irrigation system has been discussed in this paper. This system would be SCADA based and quite useful in areas where there is plenty of sunshine but insufficient water to carry out farming activities, such as rubber plantation, strawberry plantation, or any plantation, that requires frequent watering. The system is powered by solar system as a renewable energy which uses solar panel module to convert Sunlight into electricity. The development and implementation of an automated SCADA controlled system that uses PLC as a controller is significant to agricultural, oil and gas monitoring and control purpose purposes. In addition, the system is powered by an intelligent solar system in which solar panel targets the radiation from the Sun. Other than that, the solar system has reduced energy cost as well as pollution. The system is equipped with four input sensors; two soil moisture sensors, two level detection sensors. Soil moisture sensor measures the humidity of the soil, whereas the level detection sensors detect the level of water in the tank. The output sides consist of two solenoid valves, which are controlled respectively by two moistures sensors.", "author_names": [ "Ali Issa Abdelkerim", "M M R Sami Eusuf", "M Salami", "Abiodun Musa Aibinu", "Muhammad Abu Eusuf" ], "corpus_id": 108507562, "doc_id": "108507562", "n_citations": 15, "n_key_citations": 0, "score": 0, "title": "Development of Solar Powered Irrigation System", "venue": "", "year": 2013 } ]