Pub Date : 2016-06-05DOI: 10.1109/PVSC.2016.7750242
M. Gostein, B. Stueve, B. Brophy, Ki-yul Jung, A. Martinez-Morales, Shu Zhang, Yeyi Jin, Jianmei Xu
Soiling can be a significant loss factor for PV systems, accounting for >5% annual energy loss in locations without frequent rainfall. Therefore, many manufacturers are investigating the potential benefits of incorporating anti-soiling or self-cleaning properties into PV module coatings. In order to study the potential anti-soiling behavior of various surface treatments, we have deployed a test station with custom-made PV modules having coatings with both hydrophilic and hydrophobic properties that may inhibit soiling and/or induce self-cleaning. The soiling of each sample is determined by comparison to an automatically washed reference cell in the station. We present the motivations for and design of the station, along with preliminary results regarding the impact of the coatings on soiling.
{"title":"Soiling measurement station to evaluate anti-soiling properties of PV module coatings","authors":"M. Gostein, B. Stueve, B. Brophy, Ki-yul Jung, A. Martinez-Morales, Shu Zhang, Yeyi Jin, Jianmei Xu","doi":"10.1109/PVSC.2016.7750242","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750242","url":null,"abstract":"Soiling can be a significant loss factor for PV systems, accounting for >5% annual energy loss in locations without frequent rainfall. Therefore, many manufacturers are investigating the potential benefits of incorporating anti-soiling or self-cleaning properties into PV module coatings. In order to study the potential anti-soiling behavior of various surface treatments, we have deployed a test station with custom-made PV modules having coatings with both hydrophilic and hydrophobic properties that may inhibit soiling and/or induce self-cleaning. The soiling of each sample is determined by comparison to an automatically washed reference cell in the station. We present the motivations for and design of the station, along with preliminary results regarding the impact of the coatings on soiling.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"270 1","pages":"3129-3131"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85189851","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 : 2016-06-05DOI: 10.1109/PVSC.2016.7749722
Brian L. Watson, Nicholas Rolston, Kevin A. Bush, T. Leijtens, M. McGehee, R. Dauskardt
Styrene functionalized fullerene derivatives have been designed for use as electron-selective contacts in perovskite solar cells. Unlike films of PC61BM and C60 fullerene, films of these styrene-functionalized fullerenes (SFFs) can be transformed into a solvent resistant material through thermal curing. Conventional-geometry perovskite solar cells utilizing cured and uncured thin films of SFFs on titania were fabricated and tested for PCE and fracture resistance, and compared to cells employing C60. These cells displayed significant improvements in the fracture resistance (> 200 %) while exhibiting only a 7% drop in PCE (13.8 % vs 14.8 % PCE), with larger VOC and JSC values in comparison to the C60 control cell. Inverted cells fabricated with SFFs displayed an even greater increase in fracture resistance (> 400 %) with only a 6 % reduction in PCE (12.3 % vs 13.1 %) in comparison to those utilizing PC61BM.
苯乙烯功能化富勒烯衍生物已被设计用于钙钛矿太阳能电池中的电子选择触点。与PC61BM和C60富勒烯的薄膜不同，这些苯乙烯功能化富勒烯(SFFs)的薄膜可以通过热固化转化为耐溶剂材料。利用钛上固化和未固化的SFFs薄膜制备了传统几何形状的钙钛矿太阳能电池，并对其PCE和抗断裂性能进行了测试，并与使用C60的电池进行了比较。与C60对照电池相比，这些电池在抗断裂性方面表现出显著的改善(> 200%)，而PCE仅下降7% (13.8% vs 14.8% PCE)， VOC和JSC值更大。与使用PC61BM相比，使用SFFs制作的倒置细胞显示出更大的抗骨折性增加(> 400%)，PCE仅降低6%(12.3%对13.1%)。
{"title":"Cross-linkable styrene-functionalized fullerenes as electron-selective contacts for robust and efficient perovskite solar cells","authors":"Brian L. Watson, Nicholas Rolston, Kevin A. Bush, T. Leijtens, M. McGehee, R. Dauskardt","doi":"10.1109/PVSC.2016.7749722","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7749722","url":null,"abstract":"Styrene functionalized fullerene derivatives have been designed for use as electron-selective contacts in perovskite solar cells. Unlike films of PC61BM and C60 fullerene, films of these styrene-functionalized fullerenes (SFFs) can be transformed into a solvent resistant material through thermal curing. Conventional-geometry perovskite solar cells utilizing cured and uncured thin films of SFFs on titania were fabricated and tested for PCE and fracture resistance, and compared to cells employing C60. These cells displayed significant improvements in the fracture resistance (> 200 %) while exhibiting only a 7% drop in PCE (13.8 % vs 14.8 % PCE), with larger VOC and JSC values in comparison to the C60 control cell. Inverted cells fabricated with SFFs displayed an even greater increase in fracture resistance (> 400 %) with only a 6 % reduction in PCE (12.3 % vs 13.1 %) in comparison to those utilizing PC61BM.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"53 4 1","pages":"0828-0830"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80918312","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 : 2016-06-05DOI: 10.1109/PVSC.2016.7750054
T. Dennis, C. Yasanayake, T. Gerke, A. Payne, L. Eng, Brent Fisher, M. Meitl
We built a spectrally programmable super-continuum solar simulator and applied it to the realistic laboratory testing of a multi-junction concentrator solar cell. The novel solar simulator generated a broad range of illumination conditions representing changes in time of day, time of year, and air mass. The simulator is based on a spatially coherent, super- continuum laser as the light source and a hybrid pair of prism- based spectrometers with spatial light modulators to precisely control the spectrum. The enhanced spectral coverage of this simulator significantly reduced the spectral mismatch over previous implementations. Geometries for both focused as well as divergent sample illumination were considered, achieving irradiances of approximately 100 suns and 190 suns, respectively. The measured performance of the cell was compared favorably to predictions based on both measured and theoretical spectra and representative quantum efficiency curves.
{"title":"A programmable solar simulator for realistic seasonal, diurnal, and air-mass testing of multi-junction concentrator photovoltaics","authors":"T. Dennis, C. Yasanayake, T. Gerke, A. Payne, L. Eng, Brent Fisher, M. Meitl","doi":"10.1109/PVSC.2016.7750054","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750054","url":null,"abstract":"We built a spectrally programmable super-continuum solar simulator and applied it to the realistic laboratory testing of a multi-junction concentrator solar cell. The novel solar simulator generated a broad range of illumination conditions representing changes in time of day, time of year, and air mass. The simulator is based on a spatially coherent, super- continuum laser as the light source and a hybrid pair of prism- based spectrometers with spatial light modulators to precisely control the spectrum. The enhanced spectral coverage of this simulator significantly reduced the spectral mismatch over previous implementations. Geometries for both focused as well as divergent sample illumination were considered, achieving irradiances of approximately 100 suns and 190 suns, respectively. The measured performance of the cell was compared favorably to predictions based on both measured and theoretical spectra and representative quantum efficiency curves.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"16 1","pages":"2327-2332"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80976543","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 : 2016-06-05DOI: 10.1109/PVSC.2016.7749915
C. B. Jones, M. Martínez‐Ramón, Ryan M. Smith, C. Carmignani, O. Lavrova, Charles D. Robinson, J. Stein
Current-voltage (I-V) curve traces of photovoltaic (PV) systems can provide detailed information for diagnosing fault conditions. The present work implemented an in situ, automatic I-V curve tracer system coupled with Support Vector Machine and a Gaussian Process algorithms to classify and estimate abnormal and normal PV performance. The approach successfully identified normal and fault conditions. In addition, the Gaussian Process regression algorithm was used to estimate ideal I-V curves based on a given irradiance and temperature condition. The estimation results were then used to calculate the lost power due to the fault condition.
{"title":"Automatic fault classification of photovoltaic strings based on an in situ IV characterization system and a Gaussian process algorithm","authors":"C. B. Jones, M. Martínez‐Ramón, Ryan M. Smith, C. Carmignani, O. Lavrova, Charles D. Robinson, J. Stein","doi":"10.1109/PVSC.2016.7749915","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7749915","url":null,"abstract":"Current-voltage (I-V) curve traces of photovoltaic (PV) systems can provide detailed information for diagnosing fault conditions. The present work implemented an in situ, automatic I-V curve tracer system coupled with Support Vector Machine and a Gaussian Process algorithms to classify and estimate abnormal and normal PV performance. The approach successfully identified normal and fault conditions. In addition, the Gaussian Process regression algorithm was used to estimate ideal I-V curves based on a given irradiance and temperature condition. The estimation results were then used to calculate the lost power due to the fault condition.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"35 1","pages":"1708-1713"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78518013","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 : 2016-06-05DOI: 10.1109/PVSC.2016.7750055
C. Domínguez, M. Victoria, Valentín Pérez, S. Askins, R. Herrero, I. Antón, G. Sala
An optical characterization technique is introduced for the measurement of the spectrally-resolved optical efficiency of concentrators that employ multi-junction cells. The method takes into account the optical coupling between any secondary optic and its multi-junction cell receiver and allows the latter to be used as light detector for the first time. A series of band pass filters are used to isolate the optical performance of different narrow spectral bands throughout the spectrum of interest. The subcell with a response in each narrow band is used as a light sensor. A high-intensity filtered broad band light is cast on the receiver surroundings to avoid the other subcells to limit the current. The technique presented has been key to identify solarization effects in molded soda-lime glass secondary optics exposed to outdoor operation during several months.
{"title":"Using a multi-junction cell receiver as self-detector for spectrally-resolved optical efficiency measurement of concentrators","authors":"C. Domínguez, M. Victoria, Valentín Pérez, S. Askins, R. Herrero, I. Antón, G. Sala","doi":"10.1109/PVSC.2016.7750055","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750055","url":null,"abstract":"An optical characterization technique is introduced for the measurement of the spectrally-resolved optical efficiency of concentrators that employ multi-junction cells. The method takes into account the optical coupling between any secondary optic and its multi-junction cell receiver and allows the latter to be used as light detector for the first time. A series of band pass filters are used to isolate the optical performance of different narrow spectral bands throughout the spectrum of interest. The subcell with a response in each narrow band is used as a light sensor. A high-intensity filtered broad band light is cast on the receiver surroundings to avoid the other subcells to limit the current. The technique presented has been key to identify solarization effects in molded soda-lime glass secondary optics exposed to outdoor operation during several months.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"74 1","pages":"2333-2336"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73121759","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 : 2016-06-05DOI: 10.1109/PVSC.2016.7750243
N. Guay, Clifford W. Hansen, Charles D. Robinson, B. King
Determination of module temperature coefficients for voltage, current and power requires measuring the average of cell temperatures. Conventional practice is to place thermocouples or resistive temperature devices (RTDs) at a few locations on a module's back surface and to average the readings, which may not accurately represent the average temperature over all cells. We investigate the suitability of averaging RTDs, which measure average temperature along a 1m length, to accurately measure the average cell temperature when determining temperature coefficients outdoors.
{"title":"Improving module temperature measurements using averaging resistive temperature devices","authors":"N. Guay, Clifford W. Hansen, Charles D. Robinson, B. King","doi":"10.1109/PVSC.2016.7750243","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750243","url":null,"abstract":"Determination of module temperature coefficients for voltage, current and power requires measuring the average of cell temperatures. Conventional practice is to place thermocouples or resistive temperature devices (RTDs) at a few locations on a module's back surface and to average the readings, which may not accurately represent the average temperature over all cells. We investigate the suitability of averaging RTDs, which measure average temperature along a 1m length, to accurately measure the average cell temperature when determining temperature coefficients outdoors.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"26 1","pages":"3132-3134"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76436510","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 : 2016-06-05DOI: 10.1109/PVSC.2016.7750302
Z. Bittner, M. Slocum, G. Nelson, R. Tatavarti, S. Hubbard
InAs/GaAs quantum dots (QDs) have been investigated as a potential method of engineering the bandgap of the middle junction in triple junction solar cells to better match current generation and radiation tolerance to that of the InGaP top cell. While it is possible to successfully include QDs without inducing middle junction voltage degradation, they can lead to a slight reduction of minority carrier diffusion lengths in films grown after the QDs. Switching to an inverted metamorphic structure allows for the top cell to be grown first, but leads to challenges in maintaining current collection in the middle junction. In this work, a novel InAs/GaAs QD middle junction cell design is proposed for improving the efficiency of triple junction inverted metamorphic solar cells. Conventionally designed thin emitter devices as well as the proposed thick emitter devices were grown with and without InAs QDs in the uid region of the middle junction. The conventionally designed QDSC exhibited 1.8% relative increase in Jsc over the control device with no loss in VoC resulting in a 1.8% relative increase in efficiency over the control device.
{"title":"Novel InAs/GaAs QD subcell design for radiation hard 3-J ELO IMM solar cell","authors":"Z. Bittner, M. Slocum, G. Nelson, R. Tatavarti, S. Hubbard","doi":"10.1109/PVSC.2016.7750302","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750302","url":null,"abstract":"InAs/GaAs quantum dots (QDs) have been investigated as a potential method of engineering the bandgap of the middle junction in triple junction solar cells to better match current generation and radiation tolerance to that of the InGaP top cell. While it is possible to successfully include QDs without inducing middle junction voltage degradation, they can lead to a slight reduction of minority carrier diffusion lengths in films grown after the QDs. Switching to an inverted metamorphic structure allows for the top cell to be grown first, but leads to challenges in maintaining current collection in the middle junction. In this work, a novel InAs/GaAs QD middle junction cell design is proposed for improving the efficiency of triple junction inverted metamorphic solar cells. Conventionally designed thin emitter devices as well as the proposed thick emitter devices were grown with and without InAs QDs in the uid region of the middle junction. The conventionally designed QDSC exhibited 1.8% relative increase in Jsc over the control device with no loss in VoC resulting in a 1.8% relative increase in efficiency over the control device.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"92 1","pages":"3421-3424"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76567556","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 : 2016-06-05DOI: 10.1109/PVSC.2016.7750289
F. Ye, W. Deng, Wangwu Guo, Ruimin Liu, Daming Chen, Yifeng Chen, Yang Yang, N. Yuan, Jianning Ding, Zhiqiang Feng, P. Altermatt, P. Verlinden
Passivated emitter and rear cells (PERC) on p-type monocrystalline Si wafers are currently being introduced to mass production by various manufacturers and have been widely researched. We describe and characterize our recent batch of PERC cells, fabricated on 156×156 mm2 wafers with an industrial process sequence and industrial equipment. The champion cell has an efficiency of 22.13% and a Voc of 680.3mV, confirmed by FrauhoferCalLab, and is the first world record to exceed 22% in the category of industrial-type large-area mono PERC cells with printed front and rear contacts. The improved surface passivation and optimized doping profile have reduced the saturation currents of the heavily and lightly doped emitter parts to 111 fA/cm2 and 26.3 fA/cm2, respectively, which are the main contributions to the cell efficiency improvements.
{"title":"22.13% Efficient industrial p-type mono PERC solar cell","authors":"F. Ye, W. Deng, Wangwu Guo, Ruimin Liu, Daming Chen, Yifeng Chen, Yang Yang, N. Yuan, Jianning Ding, Zhiqiang Feng, P. Altermatt, P. Verlinden","doi":"10.1109/PVSC.2016.7750289","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750289","url":null,"abstract":"Passivated emitter and rear cells (PERC) on p-type monocrystalline Si wafers are currently being introduced to mass production by various manufacturers and have been widely researched. We describe and characterize our recent batch of PERC cells, fabricated on 156×156 mm2 wafers with an industrial process sequence and industrial equipment. The champion cell has an efficiency of 22.13% and a Voc of 680.3mV, confirmed by FrauhoferCalLab, and is the first world record to exceed 22% in the category of industrial-type large-area mono PERC cells with printed front and rear contacts. The improved surface passivation and optimized doping profile have reduced the saturation currents of the heavily and lightly doped emitter parts to 111 fA/cm2 and 26.3 fA/cm2, respectively, which are the main contributions to the cell efficiency improvements.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"22 1","pages":"3360-3365"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82733497","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 : 2016-06-05DOI: 10.1109/PVSC.2016.7750041
David E. Sommer, D. Mutter, S. Dunham
Recent experimental work has revealed the distinct and beneficial role of K incorporation on the fabrication of increasingly efficient thin-film photovoltaic devices with Cu(In, Ga)Se2 (CIGS) absorber layers. This has been attributed, in part, to improved CdS/CIGS heterojunction quality due to the enhanced diffusion of Cd into the near-interface region of CIGS. In this work, we try to distinguish the role of K compared to Na in enhancing Cd incorporation in CuInSe2 (CIS) based on first-principles calculations. Using a canonical method for calculating defect concentrations as a function of temperature and material stoichiometry, we identify experimentally relevant conditions under which a simple model for Na and K kinetics can lead to such an effect. We argue that a sufficiently low migration barrier for K diffusion mediated by Cu vacancies can lead to Cu-depletion near the CdS interface, allowing Cd to occupy greater numbers of vacant Cu sites.
{"title":"First-principles calculations of Na and K impurities in CuInSe2 and their effect on Cd incorporation","authors":"David E. Sommer, D. Mutter, S. Dunham","doi":"10.1109/PVSC.2016.7750041","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750041","url":null,"abstract":"Recent experimental work has revealed the distinct and beneficial role of K incorporation on the fabrication of increasingly efficient thin-film photovoltaic devices with Cu(In, Ga)Se2 (CIGS) absorber layers. This has been attributed, in part, to improved CdS/CIGS heterojunction quality due to the enhanced diffusion of Cd into the near-interface region of CIGS. In this work, we try to distinguish the role of K compared to Na in enhancing Cd incorporation in CuInSe2 (CIS) based on first-principles calculations. Using a canonical method for calculating defect concentrations as a function of temperature and material stoichiometry, we identify experimentally relevant conditions under which a simple model for Na and K kinetics can lead to such an effect. We argue that a sufficiently low migration barrier for K diffusion mediated by Cu vacancies can lead to Cu-depletion near the CdS interface, allowing Cd to occupy greater numbers of vacant Cu sites.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"2 1","pages":"2274-2278"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82867536","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 : 2016-06-05DOI: 10.1109/PVSC.2016.7750051
Daiji Yamashita, Kentaroh Watanabe, M. Fujino, T. Hoshii, Y. Okada, Y. Nakano, T. Suga, M. Sugiyama
Room-temperature surface-activated wafer bonding between bare III-V semiconductor surfaces has become a key technology for high-efficiency multi-junction solar cells, where the reduction of interfacial electrical resistance is of crucial importance for achieving highest efficiency. In the bonding process, surface cleaning using fast atom beam (FAB) of noble gas elements is vital for successful bonding but it damages the surface, resulting in numerous crystal defects at the bonded interface and increases electrical resistance. We here developed quantitative evaluation of such defects introduced by FAB treatment. The surface of n-GaAs was treated with the FAB using Ne, Ar and Kr, and Au Schottky electrodes were formed on the surfaces. Capacitance of a Schottky diode as a function of both probe frequency and DC bias allowed us to characterize both energy depth of the defects and their density profile along the physical depth from the GaAs surface. The results indicated that atoms with the smaller diameter generate high-density defects to the deeper region from the surface. When the defect density exceeding the doping level of GaAs spreads to wider than 5 nm, significant Schottky characteristics appears in the interfacial current-voltage characteristics, as suggested by simulations. Such a tendency was semi-quantitatively in good agreement with the measured current-voltage characteristics of the n-GaAs/n-GaAs bonded interfaces treated with the FAB of Ne, Ar and Kr, suggesting that the capacitance analysis of the FAB-treated surface provides us a direction for optimizing the surface- activated bonding process using FAB.
{"title":"Admittance spectroscopy analysis on the interfacial defect levels in the surface-activated bonding of GaAs","authors":"Daiji Yamashita, Kentaroh Watanabe, M. Fujino, T. Hoshii, Y. Okada, Y. Nakano, T. Suga, M. Sugiyama","doi":"10.1109/PVSC.2016.7750051","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750051","url":null,"abstract":"Room-temperature surface-activated wafer bonding between bare III-V semiconductor surfaces has become a key technology for high-efficiency multi-junction solar cells, where the reduction of interfacial electrical resistance is of crucial importance for achieving highest efficiency. In the bonding process, surface cleaning using fast atom beam (FAB) of noble gas elements is vital for successful bonding but it damages the surface, resulting in numerous crystal defects at the bonded interface and increases electrical resistance. We here developed quantitative evaluation of such defects introduced by FAB treatment. The surface of n-GaAs was treated with the FAB using Ne, Ar and Kr, and Au Schottky electrodes were formed on the surfaces. Capacitance of a Schottky diode as a function of both probe frequency and DC bias allowed us to characterize both energy depth of the defects and their density profile along the physical depth from the GaAs surface. The results indicated that atoms with the smaller diameter generate high-density defects to the deeper region from the surface. When the defect density exceeding the doping level of GaAs spreads to wider than 5 nm, significant Schottky characteristics appears in the interfacial current-voltage characteristics, as suggested by simulations. Such a tendency was semi-quantitatively in good agreement with the measured current-voltage characteristics of the n-GaAs/n-GaAs bonded interfaces treated with the FAB of Ne, Ar and Kr, suggesting that the capacitance analysis of the FAB-treated surface provides us a direction for optimizing the surface- activated bonding process using FAB.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":"39 1","pages":"2317-2319"},"PeriodicalIF":0.0,"publicationDate":"2016-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83114151","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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