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Leonid Chernyak - One of the best experts on this subject based on the ideXlab platform.
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impact of temperature and gamma radiation on electron Diffusion Length and mobility in p type inas gasb superlattices
Journal of Applied Physics, 2018Co-Authors: Jonathan Lee, Sanjay Krishna, Leonid Chernyak, Chris J Fredricksen, Elena Flitsiyan, Robert E Peale, Zahra Taghipour, Lilian K Casias, Alireza Kazemi, S MyersAbstract:The minority Carrier Diffusion Length was directly measured by the variable-temperature Electron Beam-Induced Current technique in InAs/GaSb type-II strain-layer-superlattice infrared-detector structures. The Molecular Beam Epitaxy-grown midwave infrared superlattices comprised 10 monolayers of InAs and 10 monolayers of GaSb to give a total absorber thickness of 4 μm. The Diffusion Length of minority electrons in the p-type absorber region of the p-type/barrier/n-type structure was found to increase from 1.08 to 2.24 μm with a thermal activation energy of 13.1 meV for temperatures ranging from 77 to 273 K. These Lengths significantly exceed the individual 10-monolayer thicknesses of the InAs and GaSb, possibly indicating a low impact of interface scattering on the minority Carrier Diffusion Length. The corresponding minority electron mobility varied from 48 to 65 cm2/V s. An absorbed gamma irradiation dose of 500 Gy halved the minority Carrier Diffusion Length and increased the thermal activation energy to 18.6 meV, due to creation of radiation-induced defect recombination centers.
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electron irradiation induced increase of minority Carrier Diffusion Length mobility and lifetime in mg doped aln algan short period superlattice
Applied Physics Letters, 2007Co-Authors: O Lopatiuktirpak, Leonid Chernyak, B Borisov, V Kuryatkov, S A Nikishin, Konstantin GartsmanAbstract:Minority Carrier Diffusion Length in a p-type Mg-doped AlN∕Al0.08Ga0.92N short period superlattice was shown to undergo a multifold and persistent (for at least 1week) increase under continuous irradiation by low-energy beam of a scanning electron microscope. Since neither the Diffusion Length itself nor the rate of its increase exhibited any measurable temperature dependence, it is concluded that this phenomenon is attributable to the increase in mobility of minority electrons in the two-dimensional electron gas, which in turn is limited by defect scattering. Cathodoluminescence spectroscopy revealed ∼40% growth of Carrier lifetime under irradiation with an activation energy of 240meV.
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doping level dependence of electron irradiation induced minority Carrier Diffusion Length increase in mg doped gan
Applied Physics Letters, 2007Co-Authors: O Lopatiuktirpak, Leonid Chernyak, Yulin Wang, F Ren, S J Pearton, Konstantin GartsmanAbstract:The electron irradiation-induced increase of minority Carrier Diffusion Length was studied as a function of hole concentration in Mg-doped GaN. Variable-temperature electron beam induced current measurements yielded activation energies of 264, 254, 171, and 144meV for samples with hole concentrations of 2×1016, 9×1016, 3×1018, and 7×1018cm−3, respectively. This Carrier concentration dependence of the activation energy for the effects of electron irradiation was found to be consistent with Mg acceptors, indicating the involvement of the latter levels in the irradiation-induced Diffusion Length increase.
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Studies of minority Carrier Diffusion Length increase in p-type ZnO:Sb
Journal of Applied Physics, 2006Co-Authors: O. Lopatiuk-tirpak, Leonid Chernyak, Faxian Xiu, Jianlin Liu, S. Jang, Fan Ren, Stephen J. Pearton, Konstantin Gartsman, Yishay Feldman, Andrei OsinskyAbstract:Minority electron Diffusion Length was measured in p-type, Sb-doped ZnO as a function of temperature using the electron beam induced current technique. A thermally induced increase of electron Diffusion Length was determined to have an activation energy of 184±10meV. Irradiation with a low energy (5kV) electron beam also resulted in an increase of Diffusion Length with a similar activation energy (219±8meV). Both phenomena are suggested to involve a SbZn–2VZn acceptor complex. Saturation and relaxation dynamics of minority Carrier Diffusion Length are explored. Details of a possible mechanism for Diffusion Length increase are presented.
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electron beam induced current and cathodoluminescence studies of thermally activated increase for Carrier Diffusion Length and lifetime in n type zno
Applied Physics Letters, 2005Co-Authors: O Lopatiuk, Leonid Chernyak, A Osinsky, J Q Xie, P P ChowAbstract:Temperature dependence of the minority Carrier Diffusion Length and lifetime in bulk n-type ZnO was studied using electron-beam-induced current and cathodoluminescence techniques. The Diffusion Length was observed to increase exponentially over the temperature range from 25 °C to 125 °C, yielding activation energy of 45±2meV. Concomitant decrease of the cathodoluminescence intensity for the near-band-edge transition was also observed. The activation energy determined by optical measurements was 58±7meV. The larger minority Carrier Diffusion Length and smaller luminescence intensity are attributed to the increased lifetime of nonequilibrium holes in the valence band at elevated temperatures.
Thomas Unold - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of cross section electron beam induced current in thin film solar cells for low and high injection conditions
Journal of Applied Physics, 2013Co-Authors: M Nichterwitz, Thomas UnoldAbstract:Electron-beam induced current measurements (EBIC) in the cross-section configuration can be used to characterize electronic properties of thin-film solar-cells with a spatial resolution in the submicrometer range. Assuming low injection conditions and complete charge Carrier collection in the depletion region, the minority charge-Carrier Diffusion Length and width of the space charge region can be extracted from EBIC data using an analytical expression. In the present work, we evaluate the validity of the assumptions underlying the analytical description by using numerical device simulation to describe EBIC profiles perpendicular to the pn-junction of thin-film solar cells. We find that under low injection conditions, the analytical description provides good results if the minority charge-Carrier Diffusion Length in the absorber layer is significantly larger than the width of the space charge region. On the other hand, the analytical description of the EBIC profiles deviates significantly from the numeric...
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numerical simulation of cross section electron beam induced current in thin film solar cells for low and high injection conditions
Journal of Applied Physics, 2013Co-Authors: M Nichterwitz, Thomas UnoldAbstract:Electron-beam induced current measurements (EBIC) in the cross-section configuration can be used to characterize electronic properties of thin-film solar-cells with a spatial resolution in the submicrometer range. Assuming low injection conditions and complete charge Carrier collection in the depletion region, the minority charge-Carrier Diffusion Length and width of the space charge region can be extracted from EBIC data using an analytical expression. In the present work, we evaluate the validity of the assumptions underlying the analytical description by using numerical device simulation to describe EBIC profiles perpendicular to the pn-junction of thin-film solar cells. We find that under low injection conditions, the analytical description provides good results if the minority charge-Carrier Diffusion Length in the absorber layer is significantly larger than the width of the space charge region. On the other hand, the analytical description of the EBIC profiles deviates significantly from the numerical simulation for short Diffusion Lengths and also for high injection conditions. Experimental EBIC profiles of Cu(In,Ga)Se2 solar cells are evaluated to obtain local minority Carrier Diffusion-Lengths and to illustrate high-injection and low-injection effects in the measurements.
Konstantin Gartsman - One of the best experts on this subject based on the ideXlab platform.
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electron irradiation induced increase of minority Carrier Diffusion Length mobility and lifetime in mg doped aln algan short period superlattice
Applied Physics Letters, 2007Co-Authors: O Lopatiuktirpak, Leonid Chernyak, B Borisov, V Kuryatkov, S A Nikishin, Konstantin GartsmanAbstract:Minority Carrier Diffusion Length in a p-type Mg-doped AlN∕Al0.08Ga0.92N short period superlattice was shown to undergo a multifold and persistent (for at least 1week) increase under continuous irradiation by low-energy beam of a scanning electron microscope. Since neither the Diffusion Length itself nor the rate of its increase exhibited any measurable temperature dependence, it is concluded that this phenomenon is attributable to the increase in mobility of minority electrons in the two-dimensional electron gas, which in turn is limited by defect scattering. Cathodoluminescence spectroscopy revealed ∼40% growth of Carrier lifetime under irradiation with an activation energy of 240meV.
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doping level dependence of electron irradiation induced minority Carrier Diffusion Length increase in mg doped gan
Applied Physics Letters, 2007Co-Authors: O Lopatiuktirpak, Leonid Chernyak, Yulin Wang, F Ren, S J Pearton, Konstantin GartsmanAbstract:The electron irradiation-induced increase of minority Carrier Diffusion Length was studied as a function of hole concentration in Mg-doped GaN. Variable-temperature electron beam induced current measurements yielded activation energies of 264, 254, 171, and 144meV for samples with hole concentrations of 2×1016, 9×1016, 3×1018, and 7×1018cm−3, respectively. This Carrier concentration dependence of the activation energy for the effects of electron irradiation was found to be consistent with Mg acceptors, indicating the involvement of the latter levels in the irradiation-induced Diffusion Length increase.
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Studies of minority Carrier Diffusion Length increase in p-type ZnO:Sb
Journal of Applied Physics, 2006Co-Authors: O. Lopatiuk-tirpak, Leonid Chernyak, Faxian Xiu, Jianlin Liu, S. Jang, Fan Ren, Stephen J. Pearton, Konstantin Gartsman, Yishay Feldman, Andrei OsinskyAbstract:Minority electron Diffusion Length was measured in p-type, Sb-doped ZnO as a function of temperature using the electron beam induced current technique. A thermally induced increase of electron Diffusion Length was determined to have an activation energy of 184±10meV. Irradiation with a low energy (5kV) electron beam also resulted in an increase of Diffusion Length with a similar activation energy (219±8meV). Both phenomena are suggested to involve a SbZn–2VZn acceptor complex. Saturation and relaxation dynamics of minority Carrier Diffusion Length are explored. Details of a possible mechanism for Diffusion Length increase are presented.
Jinsong Huang - One of the best experts on this subject based on the ideXlab platform.
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lateral structure single crystal hybrid perovskite solar cells via piezoelectric poling
Advanced Materials, 2016Co-Authors: Qingfeng Dong, Yuchuan Shao, Jingfeng Song, Yanjun Fang, Stephen Ducharme, Jinsong HuangAbstract:: Single-crystal perovskite solar cells with a lateral structure yield an efficiency enhancement 44-fold that of polycrystalline thin films, due to the much longer Carrier Diffusion Length. A piezoelectric effect observed in perovskite single-crystal and the strain-generated grain-boundaries enable ion migration to form a p-i-n structure.
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organometal trihalide perovskite single crystals a next wave of materials for 25 efficiency photovoltaics and applications beyond
Journal of Physical Chemistry Letters, 2015Co-Authors: Jinsong Huang, Yuchuan Shao, Qingfeng DongAbstract:Hybrid perovskite single crystals have been recently revealed to have superior optoelectronic properties to perovskite polycrystalline thin films, especially the extraordinarily long Carrier Diffusion Length due to the eliminated grain boundaries. One question that naturally arises is whether the single crystal hybrid perovskites can be a next wave of photoactive materials for even higher-efficiency devices. This Perspective presents an overview of the historic evolution in understanding of Carrier Diffusion Length in CH3NH3PbI3, the initial investigations of the synthesis of single crystalline hybrid perovskites, and the characterization of their optoelectronic properties. Our analysis indicates that single crystalline perovskite materials have potential to further boost photovoltaic device power conversion efficiency to 25%. The potential opportunities for the fundamental study of the perovskite intrinsic properties, particularly the Carrier mobility and Carrier recombination lifetime, and other fields ...
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solvent annealing of perovskite induced crystal growth for photovoltaic device efficiency enhancement
Advanced Materials, 2014Co-Authors: Zhengguo Xiao, Qingfeng Dong, Yuchuan Shao, Yongbo Yuan, Jinsong HuangAbstract:Solvent-annealing is found to be an effective method to increase the grain size and Carrier Diffusion Lengths of trihalide perovskite materials. The Carrier Diffusion Length of MAPbI3 is increased to over 1 μm. The efficiency remains above 14.5% when the MAPbI3 thickness changes from 250 nm to 1 μm, with the highest efficiency reaching 15.6%.
Takashi Fuyuki - One of the best experts on this subject based on the ideXlab platform.
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effect of hydrogen plasma treatment on grain boundaries in polycrystalline silicon solar cell evaluated by laser beam induced current
Solar Energy Materials and Solar Cells, 2007Co-Authors: Kensuke Nishioka, Yukiharu Uraoka, Toshiki Yagi, Takashi FuyukiAbstract:Abstract Effects of hydrogen plasma treatment on minority Carrier Diffusion Length and recombination velocity at grain boundaries in polycrystalline silicon solar cells have been evaluated by the scanned laser-beam-induced current technique. We have successfully evaluated the two-dimensional minority Carrier Diffusion Length. On the basis of the evaluated Diffusion Length, the recombination velocity at the grain boundaries was obtained. The recombination velocity was improved by the hydrogen plasma treatment from 15,000—20,000 to 5000—10,000 cm/s. It was quantitatively confirmed that the hydrogen plasma treatment is very effective in both grains and grain boundaries.
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analysis of minority Carrier Diffusion Length in sic toward high quality epitaxial growth
Microelectronic Engineering, 2006Co-Authors: Tomoaki Hatayama, Yukiharu Uraoka, Hiroshi Yano, Takashi FuyukiAbstract:Homoepitaxy of 4H-SiC grown by a horizontal hot-wall chemical vapor deposition and the minority Carrier Diffusion Length were studied. With the addition of HCl during the etching and the epitaxy, an optimum growth window on the (0001@?) C face became wide. Minority Carrier Diffusion Length in SiC epilayers was evaluated by a line-scanning electron-beam-induced current method.
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one shot mapping of minority Carrier Diffusion Length in polycrystalline silicon solar cells using electroluminescence
Photovoltaic Specialists Conference, 2005Co-Authors: Takashi Fuyuki, Hayato Kondo, T Yamazaki, Yu Takahashi, Y Kaji, Yukiharu UraokaAbstract:The novel technique of analyzing the spatial distribution of minority Carrier Diffusion Length was investigated in detail by utilizing the photographic surveying of electroluminescence emitted from polycrystalline Si cells. The emitted infrared light (peak waveLength: 1150 nm) from a sample cell under the forward bias was captured by a cooled CCD camera. The intensity was found to be proportional to the minority Carrier Diffusion Length regardless of the running current density, which gave the quantitative information of the minority Carrier Diffusion Length distribution with high reliability. The deteriorated areas and/or aggregation of defects were detected by a simple one-shot capturing of the emitted light.
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photographic surveying of minority Carrier Diffusion Length in polycrystalline silicon solar cells by electroluminescence
Applied Physics Letters, 2005Co-Authors: Takashi Fuyuki, Hayato Kondo, T Yamazaki, Yu Takahashi, Yukiharu UraokaAbstract:Photographic surveying of the minority Carrier Diffusion Length distribution in polycrystalline silicon solar cells was proposed. Light emission from the cell under the forward bias was captured by a charge coupled device camera. We have found that the intensity distribution of light emission clearly agreed with the mapping of minority Carrier Diffusion Length in polycrystalline silicon active layers. The emission intensity had a one-to-one relationship with the minority Carrier Diffusion Length, which yielded a semiquantitative analysis method of the Diffusion Length mapping and the detection of the deteriorated areas.