D. Cunningham, J. Wohlgemuth, R. Clark, J. Posbic, J. Zahler, M. Gleaton, D. Carlson, Z. Xia, J. Miller, Lisa Maisano
This paper reports on BP Solar's DOE sponsored Technology Pathways Partnership. The paper presents the goals, the technical approach and progress for two years. The overall goals of the program are to reach grid parity for residential and commercial markets and to increase production volumes. This program is addressing all aspects of the PV product chain including: • Solar grade silicon (SGS) development; • Implementation of Mono2™ technology (single crystal quality at multi cost); • Wafering thinner wafers using thinner wire; • Optimized cell process for thin Mono2™ to achieve a cell efficiency of 18 % in 2010; • Lower module material costs and products designed for integration into specific roof types; • Automation and process control for handling hundreds of cells per minute and; • Inverters designed with the capability to dispatch batteries. Specific accomplishments reported on in this paper include: • A manufacturing trial of Mono2™ technology from casting through module production; • Product development for a utility scale module; • Development of ThermoCool™ encapsulant to reduce module operating temperatures; • Work with Dow Corning to qualify a silicone based encapsulation system and; • Evaluation of measured versus modeled module and array performance
{"title":"Reaching grid parity using BP Solar crystalline silicon technology","authors":"D. Cunningham, J. Wohlgemuth, R. Clark, J. Posbic, J. Zahler, M. Gleaton, D. Carlson, Z. Xia, J. Miller, Lisa Maisano","doi":"10.2172/993741","DOIUrl":"https://doi.org/10.2172/993741","url":null,"abstract":"This paper reports on BP Solar's DOE sponsored Technology Pathways Partnership. The paper presents the goals, the technical approach and progress for two years. The overall goals of the program are to reach grid parity for residential and commercial markets and to increase production volumes. This program is addressing all aspects of the PV product chain including: • Solar grade silicon (SGS) development; • Implementation of Mono<sup>2</sup>™ technology (single crystal quality at multi cost); • Wafering thinner wafers using thinner wire; • Optimized cell process for thin Mono<sup>2</sup>™ to achieve a cell efficiency of 18 % in 2010; • Lower module material costs and products designed for integration into specific roof types; • Automation and process control for handling hundreds of cells per minute and; • Inverters designed with the capability to dispatch batteries. Specific accomplishments reported on in this paper include: • A manufacturing trial of Mono<sup>2</sup>™ technology from casting through module production; • Product development for a utility scale module; • Development of ThermoCool™ encapsulant to reduce module operating temperatures; • Work with Dow Corning to qualify a silicone based encapsulation system and; • Evaluation of measured versus modeled module and array performance","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"22 1","pages":"001197-001202"},"PeriodicalIF":0.0,"publicationDate":"2010-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90361219","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 : 2010-06-20DOI: 10.1109/PVSC.2010.5614116
F. Pern, S. Glick, R. Sundaramoorthy, B. To, X. Li, C. Dehart, Stephen Glynn, T. Gennett, R. Noufi, T. Gessert
From our investigation of damp heat (DH)-induced degradation of the main component materials and complete CIGS devices in recent years, this paper summarizes the results on the (1) DH stability of several transparent conducting oxides deposited on glass substrates, including ZnO-based thin films, Sn-doped In2O3 (ITO), and InZnO, and (2) effectiveness of physical and chemical mitigations for ZnO. The electrical results showed that the DH-induced degradation rates of i-ZnO, AZO, their bilayer (BZO), and Al-doped Zn1−xMgxO are significantly greater than those of ITO and InZnO. Thicker AZO films are more stable than thinner ones. Structurally, upon DH exposures, the hexagonal ZnO-based thin films are transformed into highly resistive Zn(OH)2 and/or cubic ZnO with increased transmittance and substantial morphological changes. In the physical mitigation approach, plasma-enhanced chemical vapor-deposited SiOxNy and sputter-deposited InZnO are employed separately as moisture barriers to protect the underlying i-ZnO, AZO, and/or BZO with good results. However, the SiOxNy films required working with chemical treatments to improve adhesion to the BZO surfaces. In the chemical mitigation method, simple wet-solution treatments using special formulations are found effective to protect BZO from DH attack.
{"title":"Damp-heat instability and mitigation of ZnO-based thin films for CuInGaSe2 solar cells","authors":"F. Pern, S. Glick, R. Sundaramoorthy, B. To, X. Li, C. Dehart, Stephen Glynn, T. Gennett, R. Noufi, T. Gessert","doi":"10.1109/PVSC.2010.5614116","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5614116","url":null,"abstract":"From our investigation of damp heat (DH)-induced degradation of the main component materials and complete CIGS devices in recent years, this paper summarizes the results on the (1) DH stability of several transparent conducting oxides deposited on glass substrates, including ZnO-based thin films, Sn-doped In2O3 (ITO), and InZnO, and (2) effectiveness of physical and chemical mitigations for ZnO. The electrical results showed that the DH-induced degradation rates of i-ZnO, AZO, their bilayer (BZO), and Al-doped Zn1−xMgxO are significantly greater than those of ITO and InZnO. Thicker AZO films are more stable than thinner ones. Structurally, upon DH exposures, the hexagonal ZnO-based thin films are transformed into highly resistive Zn(OH)2 and/or cubic ZnO with increased transmittance and substantial morphological changes. In the physical mitigation approach, plasma-enhanced chemical vapor-deposited SiOxNy and sputter-deposited InZnO are employed separately as moisture barriers to protect the underlying i-ZnO, AZO, and/or BZO with good results. However, the SiOxNy films required working with chemical treatments to improve adhesion to the BZO surfaces. In the chemical mitigation method, simple wet-solution treatments using special formulations are found effective to protect BZO from DH attack.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"29 1","pages":"001166-001171"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74921781","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 : 2010-06-20DOI: 10.1109/PVSC.2010.5614564
D. Guttler, A. Chirilă, S. Seyrling, P. Blosch, S. Buecheler, X. Fontané, V. Izquierdo‐Roca, L. Calvo‐Barrio, A. Pérez‐Rodríguez, J. Morante, A. Eicke, A. Tiwari
The sodium supply via thermal evaporation of NaF during different stages of a three-stage Cu(In,Ga)Se2 (CIGS) evaporation process has been investigated. Solar cells were processed on soda lime glass with Si3N4 diffusion barrier and on polyimide foils at low substrate temperature of 475°C compatible with the stability of the polyimide foil. Secondary electron micrographs (SEM) of CIGS layers show inhomogeneous microstructure containing regions of small grains near the back contact when sodium is evaporated during the 1st and the 2nd CIGS growth stage, respectively. The CIGS layer structure is affected only to minor extent if sodium is incorporated in the 3rd stage. In order to correlate the layer inhomogeneities with the composition profiles, the CIGS layers were investigated with depth resolved Raman scattering and sputtered neutral mass spectroscopy (SNMS). Both analyzing techniques reveal a strongly graded composition across the CIGS absorber, with an intermediate Ga-poor region and Ga-rich surface and back regions. The performance of resulting solar cells was characterized by means of current-voltage (J-V) and external quantum efficiency (EQE) measurements. It is found that the photovoltaic performance of the cells depends significantly on the NaF incorporation method. Cells developed with a low temperature growth process yielded high efficiencies of up to 16.4% without antireflection coating when NaF was supplied during the 3rd stage of the CIGS growth process.
{"title":"Influence of NaF incorporation during Cu(In,Ga)Se2 growth on microstructure and photovoltaic performance","authors":"D. Guttler, A. Chirilă, S. Seyrling, P. Blosch, S. Buecheler, X. Fontané, V. Izquierdo‐Roca, L. Calvo‐Barrio, A. Pérez‐Rodríguez, J. Morante, A. Eicke, A. Tiwari","doi":"10.1109/PVSC.2010.5614564","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5614564","url":null,"abstract":"The sodium supply via thermal evaporation of NaF during different stages of a three-stage Cu(In,Ga)Se2 (CIGS) evaporation process has been investigated. Solar cells were processed on soda lime glass with Si3N4 diffusion barrier and on polyimide foils at low substrate temperature of 475°C compatible with the stability of the polyimide foil. Secondary electron micrographs (SEM) of CIGS layers show inhomogeneous microstructure containing regions of small grains near the back contact when sodium is evaporated during the 1st and the 2nd CIGS growth stage, respectively. The CIGS layer structure is affected only to minor extent if sodium is incorporated in the 3rd stage. In order to correlate the layer inhomogeneities with the composition profiles, the CIGS layers were investigated with depth resolved Raman scattering and sputtered neutral mass spectroscopy (SNMS). Both analyzing techniques reveal a strongly graded composition across the CIGS absorber, with an intermediate Ga-poor region and Ga-rich surface and back regions. The performance of resulting solar cells was characterized by means of current-voltage (J-V) and external quantum efficiency (EQE) measurements. It is found that the photovoltaic performance of the cells depends significantly on the NaF incorporation method. Cells developed with a low temperature growth process yielded high efficiencies of up to 16.4% without antireflection coating when NaF was supplied during the 3rd stage of the CIGS growth process.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"21 1","pages":"003420-003424"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75487000","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 : 2010-06-20DOI: 10.1109/PVSC.2010.5616634
E. Lund, Jeffrey L. Johnson, W. M. Hlaing Oo, M. Scarpulla
This study investigates the synthesis of chalcopyrite Cu2Si1−xSnxS3 (CSTS) thin films for photovoltaic solar cell absorber layers. Preliminary results indicate that layered sputtering of Cu, Sn, and Si followed by annealing in a sulfur atmosphere at 500°C does not provide adequate mixing or sulfur incorporation. Annealing/sulfurizing a homogeneous co-sputtered film of Cu, Sn, and S lead to CSTS formation, although low sulfur incorporation and undesired copper sulfide phase formation resolved. Sputtering from sulfide targets may lead to formation of CSTS.
{"title":"Investigating sputtered Cu2Si1−xSnxS3 [CSTS] for earth abundant thin film photovoltaics","authors":"E. Lund, Jeffrey L. Johnson, W. M. Hlaing Oo, M. Scarpulla","doi":"10.1109/PVSC.2010.5616634","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5616634","url":null,"abstract":"This study investigates the synthesis of chalcopyrite Cu2Si1−xSnxS3 (CSTS) thin films for photovoltaic solar cell absorber layers. Preliminary results indicate that layered sputtering of Cu, Sn, and Si followed by annealing in a sulfur atmosphere at 500°C does not provide adequate mixing or sulfur incorporation. Annealing/sulfurizing a homogeneous co-sputtered film of Cu, Sn, and S lead to CSTS formation, although low sulfur incorporation and undesired copper sulfide phase formation resolved. Sputtering from sulfide targets may lead to formation of CSTS.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"33 1","pages":"001948-001950"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73985569","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 : 2010-06-20DOI: 10.1109/PVSC.2010.5617166
S. Marsillac, V. Ranjan, S. Little, R. Collins
High efficiency CuIn1-xGaxSe2 (CIGS) thin film solar cells are produced by two-stage or three-stage co-evaporation processes. Both of these methods involve a Cu-rich to Cu-poor transition. One way to control the Cu-rich to Cu-poor transition is the so-called end point detection (EPD), which monitors the change of emissivity of the film as it changes from Cu-rich to Cu-poor. This method, however, depends on the thermal response of the substrate and the location of the corresponding thermocouple, which can lead to delays in observing the phase transitions. Presented here is a novel, nondestructive way to detect the presence of such phase changes from Cu-rich to Cu-poor or vice-versa. In this study we have relied on the high sensitivity of real time spectroscopic ellipsometry (RTSE) to simultaneously measure multiple structural and electronic properties of the absorber layer by extracting dielectric functions throughout the deposition.
{"title":"In-situ study of CIGS dielectric function as a function of copper content","authors":"S. Marsillac, V. Ranjan, S. Little, R. Collins","doi":"10.1109/PVSC.2010.5617166","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5617166","url":null,"abstract":"High efficiency CuIn1-xGaxSe2 (CIGS) thin film solar cells are produced by two-stage or three-stage co-evaporation processes. Both of these methods involve a Cu-rich to Cu-poor transition. One way to control the Cu-rich to Cu-poor transition is the so-called end point detection (EPD), which monitors the change of emissivity of the film as it changes from Cu-rich to Cu-poor. This method, however, depends on the thermal response of the substrate and the location of the corresponding thermocouple, which can lead to delays in observing the phase transitions. Presented here is a novel, nondestructive way to detect the presence of such phase changes from Cu-rich to Cu-poor or vice-versa. In this study we have relied on the high sensitivity of real time spectroscopic ellipsometry (RTSE) to simultaneously measure multiple structural and electronic properties of the absorber layer by extracting dielectric functions throughout the deposition.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"103 1","pages":"000866-000868"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74567138","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 : 2010-06-20DOI: 10.1109/PVSC.2010.5614457
Qihua Fan, G. Hou, X. Liao, X. Xiang, Chang-Nan Chen, W. Ingler, N. Adiga, Shibin Zhang, Xinmin Cao, W. Du, X. Deng
Amorphous silicon (a-Si) and amorphous silicon germanium (a-SiGe) absorber layers are deposited at high rates of 7∼8 Å/sec using RF plasma enhanced chemical vapor deposition. The single junction a-Si top and a-SiGe bottom cells deposited at such a high rate exhibit initial efficiencies of 10.06% and 9.96%, respectively, while the process is not yet fully optimized. A tandem junction cell made using the high rate deposited a-Si and a-SiGe shows an initial efficiency as high as 11.04%. A combination of proper RF power density, gas pressure, and H2 dilution enables the intrinsic layers being deposited near a depletion condition and is responsible for the promising performances.
{"title":"High rate deposition of a-Si and a-SiGe solar cells near depletion condition","authors":"Qihua Fan, G. Hou, X. Liao, X. Xiang, Chang-Nan Chen, W. Ingler, N. Adiga, Shibin Zhang, Xinmin Cao, W. Du, X. Deng","doi":"10.1109/PVSC.2010.5614457","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5614457","url":null,"abstract":"Amorphous silicon (a-Si) and amorphous silicon germanium (a-SiGe) absorber layers are deposited at high rates of 7∼8 Å/sec using RF plasma enhanced chemical vapor deposition. The single junction a-Si top and a-SiGe bottom cells deposited at such a high rate exhibit initial efficiencies of 10.06% and 9.96%, respectively, while the process is not yet fully optimized. A tandem junction cell made using the high rate deposited a-Si and a-SiGe shows an initial efficiency as high as 11.04%. A combination of proper RF power density, gas pressure, and H2 dilution enables the intrinsic layers being deposited near a depletion condition and is responsible for the promising performances.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"33 1","pages":"001491-001495"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74827430","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 : 2010-06-20DOI: 10.1109/PVSC.2010.5615856
A. Masolin, J. Vaes, F. Dross, J. Poortmans, R. Mertens
The SLIM-Cut method [1] addresses one of the most important challenges of crystalline-Si for photovoltaics: kerf-free wafering of substrates as thin as 50 microns. The SLIM-Cut technology is fully based on mechanical stress and it is compatible with low-cost fabrication methods: a stress field is applied to a silicon wafer so that a crack propagates in the silicon substrate parallel to the surface at a given depth. The top silicon layer is separated from the parent substrate and processed into a solar cell.
{"title":"Thermal curing of crystallographic defects on a slim-cut silicon foil","authors":"A. Masolin, J. Vaes, F. Dross, J. Poortmans, R. Mertens","doi":"10.1109/PVSC.2010.5615856","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5615856","url":null,"abstract":"The SLIM-Cut method [1] addresses one of the most important challenges of crystalline-Si for photovoltaics: kerf-free wafering of substrates as thin as 50 microns. The SLIM-Cut technology is fully based on mechanical stress and it is compatible with low-cost fabrication methods: a stress field is applied to a silicon wafer so that a crack propagates in the silicon substrate parallel to the surface at a given depth. The top silicon layer is separated from the parent substrate and processed into a solar cell.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"17 1","pages":"002180-002183"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78761210","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 : 2010-06-20DOI: 10.1109/PVSC.2010.5617121
Y. Kuo, Chen-Han Lin, Minghao Zhu
A novel thin-film poly-Si fabrication process has been demonstrated. This low thermal budget process transforms the multilayer amorphous silicon thin film stack into a poly-Si stack in one simple step over a very short period of time without deteriorating the underneath glass substrate. The experimental result of the unique vertical crystallization process including the mechanism is discussed. Influences of the dopant type and process parameters on crystal structure will be revealed. This new process potentially enables the economic production of large-area thin-film poly-Si solar cells at a high throughput.
{"title":"A novel low thermal budget thin-film polysilicon fabrication process for large-area, high-throughput solar cell production","authors":"Y. Kuo, Chen-Han Lin, Minghao Zhu","doi":"10.1109/PVSC.2010.5617121","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5617121","url":null,"abstract":"A novel thin-film poly-Si fabrication process has been demonstrated. This low thermal budget process transforms the multilayer amorphous silicon thin film stack into a poly-Si stack in one simple step over a very short period of time without deteriorating the underneath glass substrate. The experimental result of the unique vertical crystallization process including the mechanism is discussed. Influences of the dopant type and process parameters on crystal structure will be revealed. This new process potentially enables the economic production of large-area thin-film poly-Si solar cells at a high throughput.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"10 1-2 1","pages":"003698-003701"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78398686","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 : 2010-06-20DOI: 10.1109/PVSC.2010.5615899
S. Baek, J. H. Kim, Jang-Kyoo Shin
The influence of thickness of optimized Al-doped zinc oxide (AZO) front contact layer on an efficiency of a radial p-n junction silicon (Si) solar cell has been studied. Vertically aligned Si wire arrays for the radial p-n junction solar device were fabricated by metal catalytic etching and p-n junction was prepared by spin-on-dopant (SOD) diffusion method. AZO thin films as a top contact layer were conformally deposited on the radial p-n junction Si solar cell by atomic layer deposition (ALD) technique. To determine the best conversion efficiency, the thickness of AZO thin film varied from 15 nm to 80nm. Both short circuit current (Jsc) and power conversion efficiency (η) of the cell increased as the thickness of AZO film is changed from 15nm to 48nm, but decreased at the AZO thicknesses exceeding 48nm. The conversion efficiency of the best sample is 5.6% and Jsc of 22.2mA/cm2, when the thickness of AZO front contact is 48nm. It is considered that the optimized AZO contact layer plays a role of increasing photocurrent by lowering contact resistance and surface recombination centers.
{"title":"Fabrication and optimization of Al-doped zinc oxide layer for application in radial p-n junction silicon solar cells","authors":"S. Baek, J. H. Kim, Jang-Kyoo Shin","doi":"10.1109/PVSC.2010.5615899","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5615899","url":null,"abstract":"The influence of thickness of optimized Al-doped zinc oxide (AZO) front contact layer on an efficiency of a radial p-n junction silicon (Si) solar cell has been studied. Vertically aligned Si wire arrays for the radial p-n junction solar device were fabricated by metal catalytic etching and p-n junction was prepared by spin-on-dopant (SOD) diffusion method. AZO thin films as a top contact layer were conformally deposited on the radial p-n junction Si solar cell by atomic layer deposition (ALD) technique. To determine the best conversion efficiency, the thickness of AZO thin film varied from 15 nm to 80nm. Both short circuit current (Jsc) and power conversion efficiency (η) of the cell increased as the thickness of AZO film is changed from 15nm to 48nm, but decreased at the AZO thicknesses exceeding 48nm. The conversion efficiency of the best sample is 5.6% and Jsc of 22.2mA/cm2, when the thickness of AZO front contact is 48nm. It is considered that the optimized AZO contact layer plays a role of increasing photocurrent by lowering contact resistance and surface recombination centers.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"21 1","pages":"001788-001792"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75115343","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 : 2010-06-20DOI: 10.1109/PVSC.2010.5616538
K. Saito, Michio Kondo
Mechanism of the <110> preferential orientation in microcrystalline silicon (μc-Si) associated with deposition radicals is investigated by comparison of degrees of crystalline orientation to the radical density estimated by solving simultaneous balancing equations as a function of a SiH4 flow rate under the constant flow rate of H2. The calculation result shows that a few percent of Si2H5 radical is involved in the deposition radicals as the second largest number of radicals, and that it increases as a SiH4 flow rate increases. Agreement of its increase with the increase of (220) orientation suggests that dimeric radicals concern with the crystalline growth in the <110> direction. Furthermore, dependence of post-oxidation properties on crystalline orientation controlled by ratio of SiH4/H2 is investigated. While the crystalline volume fraction of the samples are almost equivalent at around 0.7 ∼ 0.8 and the crystalline grain sizes are almost identical between the samples, the post-oxidation properties are much different between the samples and strongly depend on the crystalline orientation. Another influence of SiH4/H2 ratio on μc-Si film growth, presumably etching of a-Si phase at the grain boundaries, is inferred from the infrared absorption spectra of the Si-Hn stretching mode which suggest the change of a-Si passivation condition on the grain boundaries depending on the crystalline orientation.
{"title":"Mechanism of <110> preferential orientation in microcrystalline silicon growth and its influence on post-oxidation property","authors":"K. Saito, Michio Kondo","doi":"10.1109/PVSC.2010.5616538","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5616538","url":null,"abstract":"Mechanism of the <110> preferential orientation in microcrystalline silicon (μc-Si) associated with deposition radicals is investigated by comparison of degrees of crystalline orientation to the radical density estimated by solving simultaneous balancing equations as a function of a SiH4 flow rate under the constant flow rate of H2. The calculation result shows that a few percent of Si2H5 radical is involved in the deposition radicals as the second largest number of radicals, and that it increases as a SiH4 flow rate increases. Agreement of its increase with the increase of (220) orientation suggests that dimeric radicals concern with the crystalline growth in the <110> direction. Furthermore, dependence of post-oxidation properties on crystalline orientation controlled by ratio of SiH4/H2 is investigated. While the crystalline volume fraction of the samples are almost equivalent at around 0.7 ∼ 0.8 and the crystalline grain sizes are almost identical between the samples, the post-oxidation properties are much different between the samples and strongly depend on the crystalline orientation. Another influence of SiH4/H2 ratio on μc-Si film growth, presumably etching of a-Si phase at the grain boundaries, is inferred from the infrared absorption spectra of the Si-Hn stretching mode which suggest the change of a-Si passivation condition on the grain boundaries depending on the crystalline orientation.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"70 1","pages":"003729-003734"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77388537","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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