Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6925639
Pratibha Sharma, M. Wilkins, H. Schriemer, K. Hinzer
A two-dimensional, distributed resistance model for a four junction solar cell is implemented in SPICE. Efficiency estimates for Gaussian irradiance profiles with different peak-to-average ratios (PAR) are determined via grid optimization at concentrations of 500, 1000 and 2000 suns. Optimizing finger spacing for a PAR of 6 improves cell efficiency by 1.8% (absolute) at 2000 suns compared to that observed from finger spacing optimized for a uniform illumination. To address the impact of chromatic aberration on cell efficiency, a CPV system is modeled in Zemax for a geometric concentration of 1250X. Using a finger spacing optimized for uniform irradiance at the average optical efficiency of 82%, the neglect of chromatic aberration was found to overstate system efficiency by 3% (absolute).
{"title":"Modeling nonuniform irradiance and chromatic aberration effects in a four junction solar cell using SPICE","authors":"Pratibha Sharma, M. Wilkins, H. Schriemer, K. Hinzer","doi":"10.1109/PVSC.2014.6925639","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925639","url":null,"abstract":"A two-dimensional, distributed resistance model for a four junction solar cell is implemented in SPICE. Efficiency estimates for Gaussian irradiance profiles with different peak-to-average ratios (PAR) are determined via grid optimization at concentrations of 500, 1000 and 2000 suns. Optimizing finger spacing for a PAR of 6 improves cell efficiency by 1.8% (absolute) at 2000 suns compared to that observed from finger spacing optimized for a uniform illumination. To address the impact of chromatic aberration on cell efficiency, a CPV system is modeled in Zemax for a geometric concentration of 1250X. Using a finger spacing optimized for uniform irradiance at the average optical efficiency of 82%, the neglect of chromatic aberration was found to overstate system efficiency by 3% (absolute).","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"18 1","pages":"3293-3297"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84584261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6925134
J. Levrat, C. Allébe, N. Badel, L. Barraud, M. Bonnet-eymard, J. Champliaud, F. Debrot, A. Descoeudres, A. Faes, A. Lachowicz, S. Nicolay, L. Sansonnens, C. Ballif, J. Geissbühler, S. D. Wolf, M. Despeisse
Silicon heterojunction solar cell technology (HJT) takes advantage of ultra-thin amorphous silicon layers deposited on both sides of monocrystalline silicon wafers, enabling excellent silicon wafer surface passivation resulting in high device power output and in addition to efficient use of thin wafers. A full cell processing platform was developed in our laboratory, enabling to achieve > 22 % cell efficiency. Advanced concepts for metallization and interconnection are under study, from fine-line printing combined with SmartWire interconnection to Copper plating. Importantly, we show that the HJT technology intrinsically enables high bifaciality of the cells (> 95 %), and further demonstrates a low thermal coefficient (<; 0.2 - 0.3 %/°C). The high performance of heterojunction cells and SmartWire interconnection based modules allow for very low cost of electricity for Heterojunction based solar systems, with a potential below 6 Euro cents per kWh in Europe, bringing photovoltaics as a very competitive electricity source. It further provides upgrade potential towards 24 % cell efficiency.
{"title":"High-performance hetero-junction crystalline silicon photovoltaic technology","authors":"J. Levrat, C. Allébe, N. Badel, L. Barraud, M. Bonnet-eymard, J. Champliaud, F. Debrot, A. Descoeudres, A. Faes, A. Lachowicz, S. Nicolay, L. Sansonnens, C. Ballif, J. Geissbühler, S. D. Wolf, M. Despeisse","doi":"10.1109/PVSC.2014.6925134","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925134","url":null,"abstract":"Silicon heterojunction solar cell technology (HJT) takes advantage of ultra-thin amorphous silicon layers deposited on both sides of monocrystalline silicon wafers, enabling excellent silicon wafer surface passivation resulting in high device power output and in addition to efficient use of thin wafers. A full cell processing platform was developed in our laboratory, enabling to achieve > 22 % cell efficiency. Advanced concepts for metallization and interconnection are under study, from fine-line printing combined with SmartWire interconnection to Copper plating. Importantly, we show that the HJT technology intrinsically enables high bifaciality of the cells (> 95 %), and further demonstrates a low thermal coefficient (<; 0.2 - 0.3 %/°C). The high performance of heterojunction cells and SmartWire interconnection based modules allow for very low cost of electricity for Heterojunction based solar systems, with a potential below 6 Euro cents per kWh in Europe, bringing photovoltaics as a very competitive electricity source. It further provides upgrade potential towards 24 % cell efficiency.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"62 1","pages":"1218-1222"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84928815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6925259
F. Hsu, Chiang-Ting Chen, Cheng-Hung Li, C. Chen, Y. Chen
Charge transport in a percolated network resulted from the mixing of donor (polymer) and acceptor materials is one of the important issues in improving the performance of polymer solar cells. We demonstrate a simple approach to enhance the performance of polymer solar cells based on poly(3-hexythiophene) (P3HT):fullerene blend incorporating a small amount of magnetic FePt-nanowires (FePt-NWs) as an additive. The photoactive film was prepared under the application of a magnetic field perpendicular to the substrate during solvent drying process. The power conversion efficiency has been improved up to ~ 60% for the treated cells. The improved device performance can be attributed to the overall improvement of polymer crystallinity.
{"title":"The application of a magnetic field to improve polymer: Fullerence solar cell performance","authors":"F. Hsu, Chiang-Ting Chen, Cheng-Hung Li, C. Chen, Y. Chen","doi":"10.1109/PVSC.2014.6925259","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925259","url":null,"abstract":"Charge transport in a percolated network resulted from the mixing of donor (polymer) and acceptor materials is one of the important issues in improving the performance of polymer solar cells. We demonstrate a simple approach to enhance the performance of polymer solar cells based on poly(3-hexythiophene) (P3HT):fullerene blend incorporating a small amount of magnetic FePt-nanowires (FePt-NWs) as an additive. The photoactive film was prepared under the application of a magnetic field perpendicular to the substrate during solvent drying process. The power conversion efficiency has been improved up to ~ 60% for the treated cells. The improved device performance can be attributed to the overall improvement of polymer crystallinity.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"503 1","pages":"1750-1753"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85626638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6925664
R. Tatavarti, K. Ban, A. Wibowo, D. Kuciauskas, H. Guthrey, K. Jones, S. Johnston, A. Norman, D. Levi, M. Al‐Jassim
Time-resolved photoluminescence (TRPL) measurements indicated minority carrier lifetimes of 15 ns for electrons in 2-μm thick layers of 1.0-eV p-In0.27Ga0.73As grown on 6-inch GaAs wafers. Electron lifetimes increased from 10 ns to 15 ns as the thickness of 1.0-eV p-In0.27Ga0.73As was increased from 0.5 μm to 2 μm. The electron lifetimes decreased from 15 ns for a p-InxGa1-xAs with a doping density of 1×1017 cm-3 to 5 ns for a doping density of 5×1017 cmq̑3. Cathodoluminescence imaging measurements indicated dislocation densities of 7.9×105 cm-2 for a 1.0-μm thick layer of p-In0.27Ga0.73As (1.0eV) at the center of the wafer and 1.4×106 cm-2 towards the edge. Cross-section transmission electron microscopy studies were performed to study dislocation blocking and threading dislocation propagation through the metamorphic graded AllnGaAs layers.
{"title":"Minority carrier lifetimes in 1.0-eV p-In0.27Ga0.73As layers grown on GaAs substrates","authors":"R. Tatavarti, K. Ban, A. Wibowo, D. Kuciauskas, H. Guthrey, K. Jones, S. Johnston, A. Norman, D. Levi, M. Al‐Jassim","doi":"10.1109/PVSC.2014.6925664","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925664","url":null,"abstract":"Time-resolved photoluminescence (TRPL) measurements indicated minority carrier lifetimes of 15 ns for electrons in 2-μm thick layers of 1.0-eV p-In<sub>0.27</sub>Ga<sub>0.73</sub>As grown on 6-inch GaAs wafers. Electron lifetimes increased from 10 ns to 15 ns as the thickness of 1.0-eV p-In<sub>0.27</sub>Ga<sub>0.73</sub>As was increased from 0.5 μm to 2 μm. The electron lifetimes decreased from 15 ns for a p-In<sub>x</sub>Ga<sub>1-x</sub>As with a doping density of 1×10<sup>17</sup> cm<sup>-3</sup> to 5 ns for a doping density of 5×10<sup>17</sup> cm<sup>q̑3</sup>. Cathodoluminescence imaging measurements indicated dislocation densities of 7.9×10<sup>5</sup> cm<sup>-2</sup> for a 1.0-μm thick layer of p-In<sub>0.27</sub>Ga<sub>0.73</sub>As (1.0eV) at the center of the wafer and 1.4×10<sup>6</sup> cm<sup>-2</sup> towards the edge. Cross-section transmission electron microscopy studies were performed to study dislocation blocking and threading dislocation propagation through the metamorphic graded AllnGaAs layers.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"51 1","pages":"3414-3416"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85665528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6925345
K. Schmieder, M. Yakes, C. Bailey, Z. Pulwin, M. Lumb, L. Hirst, M. González, S. Hubbard, C. Ebert, R. Walters
Single junction GaAs solar cells grown by MOCVD are fabricated over a range of growth rates targeting up to 56 μm/hr in order to evaluate the effect on photovoltaic device performance. MOCVD recipe conditions are provided. Dopant incorporation efficiency is found to increase at high growth rates, potentially due to reduced Zn desorption as the time required to deposit a monolayer of GaAs is reduced. Device results are characterized by light and dark-IV as well as external quantum efficiency and verified against bulk minority carrier lifetime data from time-resolved photoluminescence. High growth rate solar cells degrade less than 4% relative to baseline devices with Voc and Jsc losses of 1% and 3%, respectively. The comparison suggests that both bulk Shockley Read Hall (SRH) lifetime and surface recombination velocity (SRV) are affected by growth rate and contribute to a reduction in performance.
{"title":"Analysis of GaAs solar cells at High MOCVD growth rates","authors":"K. Schmieder, M. Yakes, C. Bailey, Z. Pulwin, M. Lumb, L. Hirst, M. González, S. Hubbard, C. Ebert, R. Walters","doi":"10.1109/PVSC.2014.6925345","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925345","url":null,"abstract":"Single junction GaAs solar cells grown by MOCVD are fabricated over a range of growth rates targeting up to 56 μm/hr in order to evaluate the effect on photovoltaic device performance. MOCVD recipe conditions are provided. Dopant incorporation efficiency is found to increase at high growth rates, potentially due to reduced Zn desorption as the time required to deposit a monolayer of GaAs is reduced. Device results are characterized by light and dark-IV as well as external quantum efficiency and verified against bulk minority carrier lifetime data from time-resolved photoluminescence. High growth rate solar cells degrade less than 4% relative to baseline devices with Voc and Jsc losses of 1% and 3%, respectively. The comparison suggests that both bulk Shockley Read Hall (SRH) lifetime and surface recombination velocity (SRV) are affected by growth rate and contribute to a reduction in performance.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"69 1","pages":"2130-2133"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85732926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6925113
G. Zimányi, M. Voros, I. Carbone, S. Carter
Nanoparticle solar cells show the promise of enhancing the efficiency of solar cells over the Shockley-Queisser limit due to the quantum-confinement-enhanced charge multiplication process. A fundamental challenge of nanoparticle solar cells, however, is that the same quantum confinement that enhances charge multiplication also tends to localize the carriers and thus hinders charge transport. To create a roadmap for overcoming this challenge, we developed a multi-scale transport modeling scheme that starts with ab initio modeling of individual nanoparticles, continues with extracting a few summary parameters that best characterize the physics of these nanoparticles, such as charging energies and size dependent energy levels, and finally feeds this information into a kinetic Monte Carlo hopping transport framework to simulate electron and hole transport across realistically modeled nanoparticle films and devices. We demonstrate the power of this hierarchical modeling by exploring the carrier mobilities of PbSe nanoparticle films as a function of composition, disorder and temperature, where comparison of our results with experiments is possible.
{"title":"Hierarchical modeling of electron and hole transport in nanoparticle thin films: From ab initio to Monte Carlo","authors":"G. Zimányi, M. Voros, I. Carbone, S. Carter","doi":"10.1109/PVSC.2014.6925113","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925113","url":null,"abstract":"Nanoparticle solar cells show the promise of enhancing the efficiency of solar cells over the Shockley-Queisser limit due to the quantum-confinement-enhanced charge multiplication process. A fundamental challenge of nanoparticle solar cells, however, is that the same quantum confinement that enhances charge multiplication also tends to localize the carriers and thus hinders charge transport. To create a roadmap for overcoming this challenge, we developed a multi-scale transport modeling scheme that starts with ab initio modeling of individual nanoparticles, continues with extracting a few summary parameters that best characterize the physics of these nanoparticles, such as charging energies and size dependent energy levels, and finally feeds this information into a kinetic Monte Carlo hopping transport framework to simulate electron and hole transport across realistically modeled nanoparticle films and devices. We demonstrate the power of this hierarchical modeling by exploring the carrier mobilities of PbSe nanoparticle films as a function of composition, disorder and temperature, where comparison of our results with experiments is possible.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"49 1","pages":"1124-1126"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85745045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6924875
B. Yang, Kenneth Armijo, R. K. Harrison, Kara E. Thomas, Jay Johnson, Jason M. Taylor, N. R. Sorensen
This work investigates balance of systems (BOS) connector reliability from the perspective of arc fault risk. Accelerated tests were performed on connectors for future development of a reliability model. Thousands of hours of damp heat and atmospheric corrosion tests found BOS connectors to be resilient to corrosion-related degradation. A procedure was also developed to evaluate new and aged connectors for arc fault risk. The measurements show that arc fault risk is dependent on a combination of materials composition as well as design geometry. Thermal measurements as well as optical emission spectroscopy were also performed to further characterize the arc plasma. Together, the degradation model, arc fault risk assessment technique, and characterization methods can provide operators of photovoltaic installations information necessary to develop a data-driven plan for BOS connector maintenance as well as identify opportunities for arc fault prognostics.
{"title":"Arc fault risk assessment and degradation model development for photovoltaic connectors","authors":"B. Yang, Kenneth Armijo, R. K. Harrison, Kara E. Thomas, Jay Johnson, Jason M. Taylor, N. R. Sorensen","doi":"10.1109/PVSC.2014.6924875","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6924875","url":null,"abstract":"This work investigates balance of systems (BOS) connector reliability from the perspective of arc fault risk. Accelerated tests were performed on connectors for future development of a reliability model. Thousands of hours of damp heat and atmospheric corrosion tests found BOS connectors to be resilient to corrosion-related degradation. A procedure was also developed to evaluate new and aged connectors for arc fault risk. The measurements show that arc fault risk is dependent on a combination of materials composition as well as design geometry. Thermal measurements as well as optical emission spectroscopy were also performed to further characterize the arc plasma. Together, the degradation model, arc fault risk assessment technique, and characterization methods can provide operators of photovoltaic installations information necessary to develop a data-driven plan for BOS connector maintenance as well as identify opportunities for arc fault prognostics.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"5 1","pages":"3549-3555"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80971645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6925411
Pravakar P. Rajbhandari, T. Dhakal, C. Westgate
Iron Pyrite (FeS2) is considered as a promising candidate for photovoltaic application because of its suitable band-gap, very high light absorption coefficient and the abundance of the component elements in the earth's crust. The problem however is that Iron Sulfide has several coexisting phases. Even with the same stoichiometry, it may have two different phases such as pyrite and marcasite. In this report, a phase pure iron pyrite is fabricated on a plain glass and molybdenum coated glass in an atmospheric pressure chemical vapor deposition system (APCVD) by annealing sputtered iron oxide (Fe2O3) in sulfur environment (elemental sulfur) at temperatures higher than 350°C. X-ray Diffraction measurement showed only pyrite phase and energy dispersive spectroscopy (EDS) showed 1:2 ratio for iron to sulfur. Depth profile using X-ray Photoelectron Spectroscopy showed a full conversion of iron oxide into pyrite. Increasing the temperature beyond 350°C, grain size got bigger, but pyrrhotite phase with very low resistivity started to appear.
{"title":"Thin film Iron Pyrite synthesized by sulfurization of Iron Oxide for application in photovoltaics","authors":"Pravakar P. Rajbhandari, T. Dhakal, C. Westgate","doi":"10.1109/PVSC.2014.6925411","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925411","url":null,"abstract":"Iron Pyrite (FeS2) is considered as a promising candidate for photovoltaic application because of its suitable band-gap, very high light absorption coefficient and the abundance of the component elements in the earth's crust. The problem however is that Iron Sulfide has several coexisting phases. Even with the same stoichiometry, it may have two different phases such as pyrite and marcasite. In this report, a phase pure iron pyrite is fabricated on a plain glass and molybdenum coated glass in an atmospheric pressure chemical vapor deposition system (APCVD) by annealing sputtered iron oxide (Fe2O3) in sulfur environment (elemental sulfur) at temperatures higher than 350°C. X-ray Diffraction measurement showed only pyrite phase and energy dispersive spectroscopy (EDS) showed 1:2 ratio for iron to sulfur. Depth profile using X-ray Photoelectron Spectroscopy showed a full conversion of iron oxide into pyrite. Increasing the temperature beyond 350°C, grain size got bigger, but pyrrhotite phase with very low resistivity started to appear.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"33 1","pages":"2400-2403"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78562535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6924988
Rohan P. Chaukulkar, W. Nemeth, A. Dameron, P. Stradins, S. Agarwal
We present an in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy study of the passivation mechanism in the surface passivation of Si solar cells by Al2O3 thin films deposited via atomic layer deposition (ALD) using TMA and O3 as precursors. The IR measurements suggest that during the annealing stage, the Si-H bonding near the interface decreases. We have used D-terminated c-Si internal-reflection crystals to differentiate the residual H atoms that may migrate from ALD Al2O3 films versus the residual D atoms present at the Al2O3/c-Si interface after ALD. Within the sensitivity of the ATR-FTIR spectroscopy setup of ~1012 cm-2 for Si-H bonds, we do not detect any migration of H from Al2O3 to the c-Si interface. Therefore, we conclude that the migration of O, and the subsequent restructuring of the interface during the annealing step, primarily contributes toward the chemical passivation of the Al2O3/c-Si interface.
{"title":"Study of the passivation mechanism of c-Si by Al2O3 using in situ infrared spectroscopy","authors":"Rohan P. Chaukulkar, W. Nemeth, A. Dameron, P. Stradins, S. Agarwal","doi":"10.1109/PVSC.2014.6924988","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6924988","url":null,"abstract":"We present an in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy study of the passivation mechanism in the surface passivation of Si solar cells by Al<sub>2</sub>O<sub>3</sub> thin films deposited via atomic layer deposition (ALD) using TMA and O<sub>3</sub> as precursors. The IR measurements suggest that during the annealing stage, the Si-H bonding near the interface decreases. We have used D-terminated c-Si internal-reflection crystals to differentiate the residual H atoms that may migrate from ALD Al<sub>2</sub>O<sub>3</sub> films versus the residual D atoms present at the Al<sub>2</sub>O<sub>3</sub>/c-Si interface after ALD. Within the sensitivity of the ATR-FTIR spectroscopy setup of ~10<sup>12</sup> cm<sup>-2</sup> for Si-H bonds, we do not detect any migration of H from Al<sub>2</sub>O<sub>3</sub> to the c-Si interface. Therefore, we conclude that the migration of O, and the subsequent restructuring of the interface during the annealing step, primarily contributes toward the chemical passivation of the Al<sub>2</sub>O<sub>3</sub>/c-Si interface.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"126 1","pages":"0582-0585"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85399556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6924969
A. Maros, N. Faleev, C. Honsberg
The formation of crystalline defects is studied as a function of the epitaxial layer thickness in InGaAs and GaAsSb material systems grown by molecular beam epitaxy on (001) GaAs wafers. The Sb and In composition is roughly 8% in both sets of samples while the nominal thicknesses are respectively 50, 125, 250nm and 500nm for the InGaAs structures and 100, 250 and 500nm for the GaAsSb structures. High-resolution x-ray diffraction results show that similar partial relaxation is obtained in both systems for nearly the same thickness. Consistent structural transformation of point defects into dislocation loops related to the thickness of ternary layers is revealed. This resulted in a partial relaxation of 42 and 46% in the 250 nm thick GaAsSb and InGaAs layers respectively due to a density of secondary 60° dislocation loops of ~ 1 × 109 cm-2. The relaxation increased to 64% in the 500nm thick InGaAs and to 68% for the 500nm thick GaAsSb films even though the density of 60° dislocation loops in the volume was reduced due to intersections of these dislocation loops. Explanation of revealed structural features is suggested.
{"title":"Defect creation in low lattice-mismatched epitaxial structures","authors":"A. Maros, N. Faleev, C. Honsberg","doi":"10.1109/PVSC.2014.6924969","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6924969","url":null,"abstract":"The formation of crystalline defects is studied as a function of the epitaxial layer thickness in InGaAs and GaAsSb material systems grown by molecular beam epitaxy on (001) GaAs wafers. The Sb and In composition is roughly 8% in both sets of samples while the nominal thicknesses are respectively 50, 125, 250nm and 500nm for the InGaAs structures and 100, 250 and 500nm for the GaAsSb structures. High-resolution x-ray diffraction results show that similar partial relaxation is obtained in both systems for nearly the same thickness. Consistent structural transformation of point defects into dislocation loops related to the thickness of ternary layers is revealed. This resulted in a partial relaxation of 42 and 46% in the 250 nm thick GaAsSb and InGaAs layers respectively due to a density of secondary 60° dislocation loops of ~ 1 × 109 cm-2. The relaxation increased to 64% in the 500nm thick InGaAs and to 68% for the 500nm thick GaAsSb films even though the density of 60° dislocation loops in the volume was reduced due to intersections of these dislocation loops. Explanation of revealed structural features is suggested.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"2 1","pages":"0499-0504"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85798935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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