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F Finger - One of the best experts on this subject based on the ideXlab platform.
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Relationship between absorber layer defect density and performance of a-Si:H and µc-Si:H solar cells studied over a wide range of defect densities generated by 2MeV Electron Bombardment
Solar Energy Materials and Solar Cells, 2014Co-Authors: Oleksandr Astakhov, V Smirnov, R Carius, Bart E Pieters, Yu Petrusenko, V Borysenko, F FingerAbstract:Abstract We summarize an extensive study on the impact of absorber layer defect density on the performance of amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon solar cells. To study the effects of the absorber layer defect density we subjected set of a-Si:H and μc-Si:H cells to a 2 MeV Electron Bombardment. Subsequently the cells were stepwise annealed to vary the defect density. The cells have varying thicknesses and are illuminated from either the p- or n-side. For reference we subjected i-layers to the same treatment as the cells. The procedure enabled the reversible increase of the i-layer defect density ( N S ) with two orders of magnitude according to Electron spin resonance measurements (ESR) performed on reference samples. The large variation of N S induces substantial changes in the current–voltage characteristics ( J – V ) and the external quantum efficiency spectra (EQE). These changes in device characteristics provide a solid reference for analysis and device simulations. It was found that performance of a-Si:H cells degraded weakly upon N S increase up to 10 17 cm −3 and dropped steeply as defect density was increased further. In contrast, performance of µc-Si:H cells showed continuous reduction as N S raised. By comparing p- and n-side illuminated cells we found that, for N S above 10 17 cm −3 , the p-side illuminated a-Si:H cells outperformed the n-side illuminated ones, however, the difference was barely visible at N S below 10 17 cm −3 . On the contrary, the device performance of n-side illuminated µc-Si:H cells was much more affected by the increase in defect density, as compared to the p-side illuminated cells. EQE results evidenced a significant asymmetry in collection of Electrons and holes in µc-Si:H devices, where carrier collection was limited by holes as defect density was increased. Based on the experimental data we speculate that the improvement of absorber material in terms of as-deposited defect density is not of primary importance for the performance of a-Si:H cells, whereas in μc-Si:H based solar cells, the reduction of the absorber layer defect density below the state-of-the-art levels, seems to improve the cell performance.
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performance of p and n side illuminated microcrystalline silicon solar cells following 2 mev Electron Bombardment
Applied Physics Letters, 2012Co-Authors: V Smirnov, Oleksandr Astakhov, R Carius, Bart E Pieters, Yu Petrusenko, V Borysenko, F FingerAbstract:The impact of defects on the performance of p- and n-side illuminated microcrystalline silicon solar cells is investigated. The absorber layer spin density NS is controlled over some two orders of magnitude by Electron Bombardment and subsequent annealing steps. At increased NS (between 3 × 1016 and 1018 cm−3), performance of n-side illuminated cells is much more strongly reduced relative to p-side illuminated cells, particularly with regard to short circuit current density. Quantum efficiency measurements indicate a corresponding strong asymmetry in wavelength-dependence, which has been successfully reproduced by numerical device simulations.
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variation of the defect density in a si h and μc si h based solar cells with 2 mev Electron Bombardment
Journal of Non-crystalline Solids, 2012Co-Authors: V Smirnov, Oleksandr Astakhov, R Carius, Yu Petrusenko, V Borysenko, W Bottler, F FingerAbstract:Abstract Improvement of the performance of solar cells based on amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon requires understanding of the role of the deep defects – dangling bonds – in the bulk of the intrinsic a-Si:H or μc-Si:H absorber layers. A straightforward way to understand how these defects may affect the performance of the cells is to investigate changes in the device performance upon variation in the defect density. In the present work solar cells with a-Si:H and μc-Si:H absorber layers were exposed to 2 MeV Electron Bombardment. The performance of the cells after various Bombardment doses and annealing steps was evaluated in view of the changes in the defect density of intrinsic layers, measured with ESR on nominally identical absorber layers irradiated in parallel with the cells. The defect density was varied over a range of 2 orders of magnitude. In the solar cells a strong degradation of performance is observed upon irradiation with the biggest effect on the short circuit current density JSC for both types of absorber layers. In most cases both VOC and JSC recover after the final annealing step (at 160 °C) for both types of cells.
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variation in absorber layer defect density in amorphous and microcrystalline silicon thin film solar cells with 2 mev Electron Bombardment
Japanese Journal of Applied Physics, 2012Co-Authors: V Smirnov, Oleksandr Astakhov, R Carius, Yu Petrusenko, V Borysenko, F FingerAbstract:The effect of the defect density in hydrogenated amorphous and microcrystalline silicon (a-Si:H and µc-Si:H) absorber layers on the performance of thin film solar cells was investigated. The defect density was varied reproducibly over more than two orders of magnitude by 2 MeV Electron Bombardment and subsequent thermal annealing. Considerable quantitative and qualitative differences were observed for the dependences of the cells parameters on the defect densities of a-Si:H and µc-Si:H. The experimental data suggest further possible improvement of µc-Si:H based solar cells with further reduced defect densities, while for a-Si:H based solar cells, a saturation of performance is observed below a defect density of about 1016 cm-3. Moreover, the experimental data provide an excellent database for numerical simulation over a range unavailable so far particularly in µc-Si:H based solar cells.
Jun Chen - One of the best experts on this subject based on the ideXlab platform.
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theoretical analysis and verification of Electron Bombardment induced photoconductivity in vacuum flat panel detectors
Journal of Lightwave Technology, 2021Co-Authors: Xinpeng Bai, Zhipeng Zhang, Manni Chen, Kai Wang, Juncong She, Shaozhi Deng, Jun ChenAbstract:Vacuum flat-panel detectors (VFPDs) using a cold cathode and photoconductor have important applications in large-area photodetectors; however, the mechanism for achieving high photoresponsivity must be further explored. In this article, theoretical analysis was performed to examine the Electron-Bombardment-induced photoconductivity (EBIPC) effect based on the equivalent circuit model. Formulas for photo/dark current were derived, which indicated that carrier multiplication was mainly due to energetic Electron Bombardment. The theoretical formulas also revealed the carrier multiplication mode inside the photoconductor of VFPDs and the relationship between the responsivity and device parameters. To verify the theoretical results, VFPDs with a ZnS photoconductor and ZnO nanowire cold cathode were studied. The responsivity initially increased and then decreased by increasing the photoconductor thickness. In addition, a broad dynamic range was achieved with a linear dynamic range of 106.02 dB, which was attributed to the efficient collection of carriers induced by EBIPC at the optimized thickness. Our theoretical results were validated by the experimental results and can provide guidance for developing VFPDs based on EBPIC.
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theoretical analysis and verification of Electron Bombardment induced photoconductivity in vacuum flat panel detectors
Journal of Lightwave Technology, 2021Co-Authors: Xinpeng Bai, Zhipeng Zhang, Manni Chen, Kai Wang, Juncong She, Shaozhi Deng, Jun ChenAbstract:Vacuum flat-panel detectors (VFPDs) using a cold cathode and photoconductor have important applications in large-area photodetectors; however, the mechanism for achieving high photoresponsivity must be further explored. In this study, theoretical analysis was performed to examine the Electron-Bombardment-induced photoconductivity (EBIPC) effect based on the equivalent circuit model. Formulas for photo/dark current were derived, which indicated that carrier multiplication was mainly due to energetic Electron Bombardment. The theoretical formulas also revealed the carrier multiplication mode inside the photoconductor of VFPDs and the relationship between the responsivity and device parameters. To verify the theoretical results, VFPDs with a ZnS photoconductor and ZnO nanowire cold cathode were studied. The responsivity initially increased and then decreased by increasing the photoconductor thickness. In addition, a broad dynamic range was achieved with a linear dynamic range of 106.02 dB, which was attributed to the efficient collection of carriers induced by EBIPC at the optimized thickness. Our theoretical results were validated by the experimental results and can provide guidance for developing VFPDs based on EBPIC.
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Electron Bombardment induced photoconductivity and high gain in a flat panel photodetector based on a zns photoconductor and zno nanowire field emitters
ACS Photonics, 2018Co-Authors: Zhipeng Zhang, Kai Wang, Shaozhi Deng, Keshuang Zheng, Jun ChenAbstract:Flat panel photodetectors are widely studied and implemented in large-area imaging. However, developing highly sensitive flat panel photodetectors with high internal gain is still very challenging due to material limitation where photoElectron multiplication mechanisms have to be established. In this study, we proposed to use an Electron Bombardment induced photoconductivity (EBIPC) mechanism to achieve high internal gain in a flat panel photodetector based on a ZnS photoconductor integrated with ZnO nanowire (NW) field emitters. The photoconductivity of the ZnS thin film increased significantly upon Bombardment with Electrons from the emitters, which led to an internal photoconductive gain of above 104 in a wide wavelength range. The photoresponse behaviors under different device parameters further verified that the high gain depended on the enhanced light-responsive performance of the ZnS thin film induced by the EBIPC mechanism. The proposed EBIPC mechanism is promising for use in flat panel photodetec...
Oleksandr Astakhov - One of the best experts on this subject based on the ideXlab platform.
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Relationship between absorber layer defect density and performance of a-Si:H and µc-Si:H solar cells studied over a wide range of defect densities generated by 2MeV Electron Bombardment
Solar Energy Materials and Solar Cells, 2014Co-Authors: Oleksandr Astakhov, V Smirnov, R Carius, Bart E Pieters, Yu Petrusenko, V Borysenko, F FingerAbstract:Abstract We summarize an extensive study on the impact of absorber layer defect density on the performance of amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon solar cells. To study the effects of the absorber layer defect density we subjected set of a-Si:H and μc-Si:H cells to a 2 MeV Electron Bombardment. Subsequently the cells were stepwise annealed to vary the defect density. The cells have varying thicknesses and are illuminated from either the p- or n-side. For reference we subjected i-layers to the same treatment as the cells. The procedure enabled the reversible increase of the i-layer defect density ( N S ) with two orders of magnitude according to Electron spin resonance measurements (ESR) performed on reference samples. The large variation of N S induces substantial changes in the current–voltage characteristics ( J – V ) and the external quantum efficiency spectra (EQE). These changes in device characteristics provide a solid reference for analysis and device simulations. It was found that performance of a-Si:H cells degraded weakly upon N S increase up to 10 17 cm −3 and dropped steeply as defect density was increased further. In contrast, performance of µc-Si:H cells showed continuous reduction as N S raised. By comparing p- and n-side illuminated cells we found that, for N S above 10 17 cm −3 , the p-side illuminated a-Si:H cells outperformed the n-side illuminated ones, however, the difference was barely visible at N S below 10 17 cm −3 . On the contrary, the device performance of n-side illuminated µc-Si:H cells was much more affected by the increase in defect density, as compared to the p-side illuminated cells. EQE results evidenced a significant asymmetry in collection of Electrons and holes in µc-Si:H devices, where carrier collection was limited by holes as defect density was increased. Based on the experimental data we speculate that the improvement of absorber material in terms of as-deposited defect density is not of primary importance for the performance of a-Si:H cells, whereas in μc-Si:H based solar cells, the reduction of the absorber layer defect density below the state-of-the-art levels, seems to improve the cell performance.
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performance of p and n side illuminated microcrystalline silicon solar cells following 2 mev Electron Bombardment
Applied Physics Letters, 2012Co-Authors: V Smirnov, Oleksandr Astakhov, R Carius, Bart E Pieters, Yu Petrusenko, V Borysenko, F FingerAbstract:The impact of defects on the performance of p- and n-side illuminated microcrystalline silicon solar cells is investigated. The absorber layer spin density NS is controlled over some two orders of magnitude by Electron Bombardment and subsequent annealing steps. At increased NS (between 3 × 1016 and 1018 cm−3), performance of n-side illuminated cells is much more strongly reduced relative to p-side illuminated cells, particularly with regard to short circuit current density. Quantum efficiency measurements indicate a corresponding strong asymmetry in wavelength-dependence, which has been successfully reproduced by numerical device simulations.
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variation of the defect density in a si h and μc si h based solar cells with 2 mev Electron Bombardment
Journal of Non-crystalline Solids, 2012Co-Authors: V Smirnov, Oleksandr Astakhov, R Carius, Yu Petrusenko, V Borysenko, W Bottler, F FingerAbstract:Abstract Improvement of the performance of solar cells based on amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon requires understanding of the role of the deep defects – dangling bonds – in the bulk of the intrinsic a-Si:H or μc-Si:H absorber layers. A straightforward way to understand how these defects may affect the performance of the cells is to investigate changes in the device performance upon variation in the defect density. In the present work solar cells with a-Si:H and μc-Si:H absorber layers were exposed to 2 MeV Electron Bombardment. The performance of the cells after various Bombardment doses and annealing steps was evaluated in view of the changes in the defect density of intrinsic layers, measured with ESR on nominally identical absorber layers irradiated in parallel with the cells. The defect density was varied over a range of 2 orders of magnitude. In the solar cells a strong degradation of performance is observed upon irradiation with the biggest effect on the short circuit current density JSC for both types of absorber layers. In most cases both VOC and JSC recover after the final annealing step (at 160 °C) for both types of cells.
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variation in absorber layer defect density in amorphous and microcrystalline silicon thin film solar cells with 2 mev Electron Bombardment
Japanese Journal of Applied Physics, 2012Co-Authors: V Smirnov, Oleksandr Astakhov, R Carius, Yu Petrusenko, V Borysenko, F FingerAbstract:The effect of the defect density in hydrogenated amorphous and microcrystalline silicon (a-Si:H and µc-Si:H) absorber layers on the performance of thin film solar cells was investigated. The defect density was varied reproducibly over more than two orders of magnitude by 2 MeV Electron Bombardment and subsequent thermal annealing. Considerable quantitative and qualitative differences were observed for the dependences of the cells parameters on the defect densities of a-Si:H and µc-Si:H. The experimental data suggest further possible improvement of µc-Si:H based solar cells with further reduced defect densities, while for a-Si:H based solar cells, a saturation of performance is observed below a defect density of about 1016 cm-3. Moreover, the experimental data provide an excellent database for numerical simulation over a range unavailable so far particularly in µc-Si:H based solar cells.
Victor J Herrero - One of the best experts on this subject based on the ideXlab platform.
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plasma generated analogs of interstellar carbonaceous dust theoretical modeling and Electron Bombardment
2016Co-Authors: Victor J Herrero, Belen Mate, Isabel Tanarro, Miguel Jimenezredondo, German Molpeceres, Vicente Timon, Rafael EscribanoAbstract:Gordon Research Conference: “Plasmas with Complex Interactions - Exploiting the Non-Equilibrium"; Andover, New Hampshire (USA); July 24-29, 2016; https://www.grc.org/programs.aspx?id=14428
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stability of extraterrestrial glycine under energetic particle radiation estimated from 2 kev Electron Bombardment experiments
The Astrophysical Journal, 2015Co-Authors: Belen Mate, Isabel Tanarro, Miguel Moreno, Rafael Escribano, Victor J HerreroAbstract:The destruction of solid glycine under irradiation with 2 keV Electrons has been investigated by means of IR spectroscopy. Destruction cross sections, radiolysis yields, and half-life doses were determined for samples at 20, 40, 90, and 300 K. The thickness of the irradiated samples was kept below the estimated penetration depth of the Electrons. No significant differences were obtained in the experiments below 90 K, but the destruction cross section at 300 K was larger by a factor of 2. The radiolysis yields and half-life doses are in good accordance with recent MeV proton experiments, which confirms that Electrons in the keV range can be used to simulate the effects of cosmic rays if the whole sample is effectively irradiated. In the low temperature experiments, Electron irradiation leads to the formation of residues. IR absorptions of these residues are assigned to the presence CO2, CO, OCN?, and CN? and possibly to amide bands I to III. The protection of glycine by water ice is also studied. A water ice film of ?150 nm is found to provide efficient shielding against the Bombardment of 2 keV Electrons. The results of this study show also that current Monte Carlo predictions provide a good global description of Electron penetration depths. The lifetimes estimated in this work for various environments ranging from the diffuse interstellar medium to the inner solar system, show that the survival of hypothetical primeval glycine from the solar nebula in present solar system bodies is not very likely.
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stability of carbonaceous dust analogues and glycine under uv irradiation and Electron Bombardment
Faraday Discussions, 2014Co-Authors: Belen Mate, Isabel Tanarro, Miguel Moreno, Miguel Jimenezredondo, Rafael Escribano, Victor J HerreroAbstract:The effect of UV photon (120–200 nm) and Electron (2 keV) irradiation of analogues of interstellar carbonaceous dust and of glycine were investigated by means of IR spectroscopy. Films of hydrogenated amorphous carbon (HAC), taken as dust analogues, were found to be stable under UV photon and Electron Bombardment. High fluences of photons and Electrons, of the order of 1019 cm−2, were needed for a film depletion of a few percent. UV photons were energetically more effective than Electrons for depletion and led to a certain dehydrogenation of the HAC samples, whereas Electrons led seemingly to a gradual erosion with no appreciable changes in the hydrocarbon structure. The rates of change observed may be relevant over the lifetime of a diffuse cloud, but cannot account for the rapid changes in hydrocarbon IR bands during the evolution of some proto-planetary nebulae. Glycine samples under the same photon and Electron fluxes decay at a much faster rate, but tend usually to an equilibrium value different from zero, especially at low temperatures. Reversible reactions re-forming glycine, or the build-up of less transparent products, could explain this behavior. CO2 and methylamine were identified as UV photoproducts. Electron irradiation led to a gradual disappearance of the glycine layers, also with formation of CO2. No other reaction products were clearly identified. The thicker glycine layers (a few hundred nm) were not wholly depleted, but a film of the order of the Electron penetration depth (80 nm), was totally destroyed with an Electron fluence of ∼1 × 1018 cm−2. A 60 nm ice layer on top of glycine provided only partial shielding from the 2 keV Electrons. From an energetic point of view, 2 keV Electrons are less efficient than UV photons and, according to literature data, much less efficient than MeV protons for the destruction of glycine. The use of keV Electrons to simulate effects of cosmic rays on analogues of interstellar grains should be taken with care, due to the low penetration depths of Electrons in many samples of interest.
V Smirnov - One of the best experts on this subject based on the ideXlab platform.
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Relationship between absorber layer defect density and performance of a-Si:H and µc-Si:H solar cells studied over a wide range of defect densities generated by 2MeV Electron Bombardment
Solar Energy Materials and Solar Cells, 2014Co-Authors: Oleksandr Astakhov, V Smirnov, R Carius, Bart E Pieters, Yu Petrusenko, V Borysenko, F FingerAbstract:Abstract We summarize an extensive study on the impact of absorber layer defect density on the performance of amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon solar cells. To study the effects of the absorber layer defect density we subjected set of a-Si:H and μc-Si:H cells to a 2 MeV Electron Bombardment. Subsequently the cells were stepwise annealed to vary the defect density. The cells have varying thicknesses and are illuminated from either the p- or n-side. For reference we subjected i-layers to the same treatment as the cells. The procedure enabled the reversible increase of the i-layer defect density ( N S ) with two orders of magnitude according to Electron spin resonance measurements (ESR) performed on reference samples. The large variation of N S induces substantial changes in the current–voltage characteristics ( J – V ) and the external quantum efficiency spectra (EQE). These changes in device characteristics provide a solid reference for analysis and device simulations. It was found that performance of a-Si:H cells degraded weakly upon N S increase up to 10 17 cm −3 and dropped steeply as defect density was increased further. In contrast, performance of µc-Si:H cells showed continuous reduction as N S raised. By comparing p- and n-side illuminated cells we found that, for N S above 10 17 cm −3 , the p-side illuminated a-Si:H cells outperformed the n-side illuminated ones, however, the difference was barely visible at N S below 10 17 cm −3 . On the contrary, the device performance of n-side illuminated µc-Si:H cells was much more affected by the increase in defect density, as compared to the p-side illuminated cells. EQE results evidenced a significant asymmetry in collection of Electrons and holes in µc-Si:H devices, where carrier collection was limited by holes as defect density was increased. Based on the experimental data we speculate that the improvement of absorber material in terms of as-deposited defect density is not of primary importance for the performance of a-Si:H cells, whereas in μc-Si:H based solar cells, the reduction of the absorber layer defect density below the state-of-the-art levels, seems to improve the cell performance.
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performance of p and n side illuminated microcrystalline silicon solar cells following 2 mev Electron Bombardment
Applied Physics Letters, 2012Co-Authors: V Smirnov, Oleksandr Astakhov, R Carius, Bart E Pieters, Yu Petrusenko, V Borysenko, F FingerAbstract:The impact of defects on the performance of p- and n-side illuminated microcrystalline silicon solar cells is investigated. The absorber layer spin density NS is controlled over some two orders of magnitude by Electron Bombardment and subsequent annealing steps. At increased NS (between 3 × 1016 and 1018 cm−3), performance of n-side illuminated cells is much more strongly reduced relative to p-side illuminated cells, particularly with regard to short circuit current density. Quantum efficiency measurements indicate a corresponding strong asymmetry in wavelength-dependence, which has been successfully reproduced by numerical device simulations.
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variation of the defect density in a si h and μc si h based solar cells with 2 mev Electron Bombardment
Journal of Non-crystalline Solids, 2012Co-Authors: V Smirnov, Oleksandr Astakhov, R Carius, Yu Petrusenko, V Borysenko, W Bottler, F FingerAbstract:Abstract Improvement of the performance of solar cells based on amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon requires understanding of the role of the deep defects – dangling bonds – in the bulk of the intrinsic a-Si:H or μc-Si:H absorber layers. A straightforward way to understand how these defects may affect the performance of the cells is to investigate changes in the device performance upon variation in the defect density. In the present work solar cells with a-Si:H and μc-Si:H absorber layers were exposed to 2 MeV Electron Bombardment. The performance of the cells after various Bombardment doses and annealing steps was evaluated in view of the changes in the defect density of intrinsic layers, measured with ESR on nominally identical absorber layers irradiated in parallel with the cells. The defect density was varied over a range of 2 orders of magnitude. In the solar cells a strong degradation of performance is observed upon irradiation with the biggest effect on the short circuit current density JSC for both types of absorber layers. In most cases both VOC and JSC recover after the final annealing step (at 160 °C) for both types of cells.
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variation in absorber layer defect density in amorphous and microcrystalline silicon thin film solar cells with 2 mev Electron Bombardment
Japanese Journal of Applied Physics, 2012Co-Authors: V Smirnov, Oleksandr Astakhov, R Carius, Yu Petrusenko, V Borysenko, F FingerAbstract:The effect of the defect density in hydrogenated amorphous and microcrystalline silicon (a-Si:H and µc-Si:H) absorber layers on the performance of thin film solar cells was investigated. The defect density was varied reproducibly over more than two orders of magnitude by 2 MeV Electron Bombardment and subsequent thermal annealing. Considerable quantitative and qualitative differences were observed for the dependences of the cells parameters on the defect densities of a-Si:H and µc-Si:H. The experimental data suggest further possible improvement of µc-Si:H based solar cells with further reduced defect densities, while for a-Si:H based solar cells, a saturation of performance is observed below a defect density of about 1016 cm-3. Moreover, the experimental data provide an excellent database for numerical simulation over a range unavailable so far particularly in µc-Si:H based solar cells.