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Roland Einhaus - One of the best experts on this subject based on the ideXlab platform.
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21.1% UMG Silicon Solar Cells
IEEE Journal of Photovoltaics, 2017Co-Authors: Peiting Zheng, Roland Einhaus, Fiacre Rougieux, Xinyu Zhang, Julien Degoulange, Pascal Rivat, Daniel MacdonaldAbstract:We present n-type Czochralski-grown Silicon solar cells made from 100% upgraded metallurgical grade Silicon Feedstock, with an independently certified peak efficiency of 21.1%. We look at the impact of net doping and minority carrier lifetime and mobility on the short-circuit current and the open-circuit voltage.
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High efficiency UMG Silicon solar cells: impact of compensation on cell parameters
Progress in Photovoltaics: Research and Applications, 2015Co-Authors: Fiacre Rougieux, Roland Einhaus, Daniel Macdonald, Peiting Zheng, Julien Degoulange, Christian Samundsett, Kean Chern Fong, Andreas Fell, Maxime ForsterAbstract:High efficiency solar cells have been fabricated with wafers from an n-type Czochralski grown (Cz) ingot using 100% Upgraded Metallurgical-Grade (UMG) Silicon Feedstock. The UMG cells fabricated with a passivated emitter and rear totally diffused (PERT) structure have an independently confirmed cell efficiency of 19.8%. This is the highest efficiency reported for a cell based on 100% UMG Silicon at the time of publication. The current and power losses are analysed as a function of measured material parameters, including carrier mobility, lifetime and the presence of the boron–oxygen defect. Dopant compensation is shown to reduce both the minority carrier lifetime and mobility, which significantly affects both the current and voltage of the device. Copyright © 2015 John Wiley & Sons, Ltd.
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Compensation engineering for uniform n-type Silicon ingots
Solar Energy Materials and Solar Cells, 2013Co-Authors: Maxime Forster, Roland Einhaus, Bastien Dehestru, Antoine Thomas, Erwann Fourmond, Andres Cuevas, Mustapha LemitiAbstract:This paper addresses a major issue related to the use of upgraded-metallurgical grade Silicon for n-type solar cells. We show that n-type Silicon ingots, grown from Silicon Feedstock containing both boron and phosphorus, display a vertical net doping variation which is incompatible with high-yield production of high-efficiency solar cells. As a solution, we propose to use compensation engineering, by means of gallium co-doping, and demonstrate its potential to control the net doping along the ingot height. The resulting material exhibits high minority carrier diffusion length gratefully to compensation but degrades upon illumination due to the activation of the boron-oxygen defect. This latter degradation remains an important though not unsurmountable challenge for making high-efficiency n-type solar cells with upgraded-metallurgical grade Silicon.
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Innovative Crystallisation of Multi-Crystalline Silicon Ingots from Different Types of Silicon Feedstock
2008Co-Authors: D. Camel, Roland Einhaus, F. Servant, B. Drevet, N. Enjalbert, Sébastien Dubois, F. Lissalde, J. KraiemAbstract:Solar Grade Silicon obtained by purification of metallurgical grade Silicon becomes an important source of Silicon Feedstock for the crystalline Silicon based PV industry. This paper presents a new process and furnace for the crystallization of multi-crystalline Silicon ingot, using purified metallurgical grade Silicon as Feedstock. In particular, the influence of the remaining dopant concentrations, such as Boron and Phosphorus, in purified metallurgical Silicon on the electrical characteristics of the obtained ingots, wafers and solar cells are discussed. Indications have been found that compensation of n-type and p-type dopants can lead to an improved minority carrier diffusion length, improving the overall efficiencies of solar cells: Efficiencies of 14 % have been obtained on ingots that were grown from Feedstock with relatively high concentrations of Boron (2.5x10 cm) and Phosphorus (3.5x10 cm) respectively. Although the Feedstock is n-type due to the higher concentration of Phosphorus, the ingot showed a p-type polarity with a resistivity of 0.5 Ohm-cm over 75% of its height starting from the bottom, which is due to a more effective segregation of Phosphorus. This also leads to an accumulation of Phosphorus atoms in the top region of the ingot, which turns n-type again and a transition region of high compensation.
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Silicon Feedstock for the multi-crystalline photovoltaic industry
Solar Energy Materials and Solar Cells, 2001Co-Authors: Dominique Sarti, Roland EinhausAbstract:Abstract During the last 5 years the PV industry continues to experience a strong economic growth between 15% and 30% per year. Multi-crystalline Silicon became the preferred material for PV production with a share of more than 50% of the shipped PV modules world-wide. For the first time, the available quantity of the classical Silicon Feedstock sources for the PV industry—electronic grade Silicon rejects from the Silicon and microelectronics industry—is close to be not sufficient to satisfy the requirements of the PV industry. From this situation arises the need to develop short- and long-term solutions to guarantee a sustainable supply of the PV industry with suitable Silicon Feedstock at acceptable costs. This paper presents a possible route for short- and long-term solutions to provide solar grade (SoG) Silicon Feedstock for the PV industry. On a short-term basis a twofold solution is proposed: (i) reduction of Silicon consumption by reducing the wafer thickness and the introduction of recycling scenarios for Silicon waste produced by the PV industry, (ii) introduction of very low-resistivity Silicon (0.1 Ω cm). On long term, a route towards the establishment of a SoG Silicon production based on widely available metallurgical grade Silicon is proposed. This route includes the development of suitable purification techniques. First results that allowed to lower the impurity tolerances for SoG Silicon are presented. The introduction of Silicon Feedstock with higher impurity concentrations which show a tendency to interact with crystal defects and lead to a degradation of the material performance also requires passivation concepts to achieve highly performing solar cells.
Daniel Macdonald - One of the best experts on this subject based on the ideXlab platform.
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21.1% UMG Silicon Solar Cells
IEEE Journal of Photovoltaics, 2017Co-Authors: Peiting Zheng, Roland Einhaus, Fiacre Rougieux, Xinyu Zhang, Julien Degoulange, Pascal Rivat, Daniel MacdonaldAbstract:We present n-type Czochralski-grown Silicon solar cells made from 100% upgraded metallurgical grade Silicon Feedstock, with an independently certified peak efficiency of 21.1%. We look at the impact of net doping and minority carrier lifetime and mobility on the short-circuit current and the open-circuit voltage.
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High efficiency UMG Silicon solar cells: impact of compensation on cell parameters
Progress in Photovoltaics: Research and Applications, 2015Co-Authors: Fiacre Rougieux, Roland Einhaus, Daniel Macdonald, Peiting Zheng, Julien Degoulange, Christian Samundsett, Kean Chern Fong, Andreas Fell, Maxime ForsterAbstract:High efficiency solar cells have been fabricated with wafers from an n-type Czochralski grown (Cz) ingot using 100% Upgraded Metallurgical-Grade (UMG) Silicon Feedstock. The UMG cells fabricated with a passivated emitter and rear totally diffused (PERT) structure have an independently confirmed cell efficiency of 19.8%. This is the highest efficiency reported for a cell based on 100% UMG Silicon at the time of publication. The current and power losses are analysed as a function of measured material parameters, including carrier mobility, lifetime and the presence of the boron–oxygen defect. Dopant compensation is shown to reduce both the minority carrier lifetime and mobility, which significantly affects both the current and voltage of the device. Copyright © 2015 John Wiley & Sons, Ltd.
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Impact of Metal Contamination in Silicon Solar Cells
Advanced Functional Materials, 2011Co-Authors: Gianluca Coletti, P C P Bronsveld, Wilhelm Warta, Giso Hahn, Daniel Macdonald, Bruno Ceccaroli, Karsten Wambach, Nam Le Quang, Juan M. FernandezAbstract:Summary The impact on solar cell performance of transition metals like iron, chromium, nickel, titanium and co pper is the topic of this extended abstract. Each impurity has been intentionally added to Silicon Feedstock used to gr ow p-type directionally solidified multicrystalline Silicon i ngots. A state of the art screen print solar cell process ha s been applied to wafers cut from the bottom to the top of these ingots. Adding 50 ppmwt of iron or 40 ppmwt of nickel or chromium to Silicon Feedstock, results in comparabl e solar cell performances to reference uncontaminated material in the range 40% to 70% of the ingot height. Addition of 10 ppmwt of titanium dramatically reduces the efficien cy along the entire ingot. Impurities like iron, chromium an d titanium cause a reduction in the diffusion length. Nickel d oes not reduce the diffusion length. On the other hand affe cts strongly the emitter recombination reducing the sol ar cell performance significantly. Copper has the peculiari ty to impact both bulk recombination as well as emitter recombination. A model based on Scheil distribution of impurity ha s been derived to fit the degradation along the ingot. So lar cell performance has been modeled as function of base bulk recombination and emitter recombination. The model fits very well the experimental data and has been also successfully validated. Unexpectedly, the Scheil di stribution of impurity along the ingot leaves its finger-print also at the end of the solar cell process. A measure of impurit y impact has been defined as the level of impurity which cau ses a degradation of less than 2% up to 90% of the ingot height. The advantage of this parameter is that comprises t he different impurities physical characters in one sin gle parameter, easy to compare.
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Scanning X-ray fluorescence microspectroscopy of metallic impurities in solar-grade Silicon
physica status solidi (a), 2010Co-Authors: Daniel Macdonald, Fiacre Rougieux, Yves Mansoulie, Jason Tan, Daryl L. Howard, Martin D. De Jonge, David L. Paterson, Chris RyanAbstract:A rapid scanning synchrofron-based X-ray fluorescence microprobe technique is applied to relatively impure crystalline Silicon Feedstock for solar cells. The results reveal the distributions of metallic impurities in the material over regions several millimetres in size, allowing scans across several grains. Relatively high concentrations of Fe, Cu and Zn were observed, with traces of Mn and Ni. The metals were mostly present as discrete particles up to 60 μm in size, while Cu was more uniformly distributed. More than 50% of the detected Fe was present as large particles at the grain boundaries, probably due to diffusion and precipitation during cooling. In contrast, less than 5% of the Cu resided in such large particles. The particles contained multiple metallic elements, with strongly varying proportions of their metal constituents.
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Synchrotron studies of solar-grade Silicon Feedstock and wafers
2010Co-Authors: Daniel Macdonald, Fiacre Rougieux, Yves Mansoulie, Jason Tan, David M. Paterson, Daryl L. Howard, Martin D. De Jonge, Chris RyanAbstract:Low-cost forms of solar-grade Silicon Feedstocks offer the possibility of reduced costs for photovoltaic modules. However, these materials often contain significant quantities of unwanted metallic impurities that may act to reduce the efficiency of solar cells. In this work we have applied a rapid, high resolution scanning X-Ray Fluorescence (XRF) technique, using the microspectroscopy beamline at the Australian synchrotron, to study the distribution of micron-sized metallic particles in solar-grade Silicon Feedstock. This allows insight into the formation mechanisms of these particles, and suggests possible methods for further purifying the material before casting it into ingots for solar cell production. We have also used the same technique to identify Fe-rich particles in wafers taken from the very bottom of a standard multicrystalline Silicon ingot for solar cells, in this case made from standard electronic-grade Silicon Feedstock. The iron contamination in these wafers comes from the quartz crucible used to contain the multicrystalline Silicon ingot, and forms large precipitates during ingot cooling.
Eivind Øvrelid - One of the best experts on this subject based on the ideXlab platform.
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FoXy Development of solar-grade Silicon Feedstock for crystalline wafers and cells by purification and crystallization
2009Co-Authors: Eivind Øvrelid, Simona Binetti, M. Di Sabatino, A.n. VaernesAbstract:This work reports on the results obtained in the EU project FoXy (contract nr SES6-019811). FoXy has been carried out in the 6 th Framework Program in the Sustainable Energy Systems. It consists of a Europe-wide consortium of small and medium size enterprises, research institutes and universities. The project has aimed at developing cleaning and crystallisation processes for metallurgical SoG-Si Feedstock, optimize associated cell and module processes, and set parameters for these types of Feedstock. The major goals of the project have been: (i) achieve a significant cost reduction through more efficient cleaning processes for raw materials, (ii) secure high volume production of SoG-Si, (iii) develop recycling techniques for end-of-life products, (iv) shorten the energy payback time significantly, (v) manufacture wafers on a large-scale industrial production line 150x150mm 2 aiming at 16-17% cell efficiency with increased yield. This work summarizes the highlight results of this three-year project.
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Effect of iron in Silicon Feedstock on p- and n-type multicrystalline Silicon solar cells
Journal of Applied Physics, 2008Co-Authors: Gianluca Coletti, R Kvande, Lars Arnberg, V. D. Mihailetchi, L. J. Geerligs, Eivind ØvrelidAbstract:The effect of iron contamination in multicrystalline Silicon ingots for solar cells has been investigated. Intentionally contaminated p- and n-type multicrystalline Silicon ingots were grown by adding 53 ppm by weight of iron in the Silicon Feedstock. They are compared to reference ingots produced from nonintentionally contaminated Silicon Feedstock. p-type and n-type solar cell processes were applied to wafers sliced from these ingots. The as-grown minority carrier lifetime in the iron doped ingots is about 1–2 and 6–20 μs for p and n types, respectively. After phosphorus diffusion and hydrogenation this lifetime is improved up to 50 times in the p-type ingot, and about five times in the n-type ingot. After boron/phosphorus codiffusion and hydrogenation the improvement is about ten times for the p-type ingot and about four times for the n-type ingot. The as-grown interstitial iron concentration in the p-type iron doped ingot is on the order of 1013 cm−3, representing about 10% of the total iron concentra...
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Distribution of iron in multicrystalline Silicon ingots
Journal of Applied Physics, 2008Co-Authors: R Kvande, Lars Arnberg, Gianluca Coletti, M. Di Sabatino, Eivind Øvrelid, L. J. Geerligs, C. C. SwansonAbstract:The distribution of iron in multicrystalline Silicon ingots for solar cells has been studied. A p- and a n-type multicrystalline ingot were intentionally contaminated by adding 53ppmwt (μg∕g) of iron to the Silicon Feedstock and compared to a reference p-type ingot produced from ultrapure Silicon Feedstock. The vertical total iron distribution was determined by neutron activation analysis and glow discharge mass spectrometry. For the intentionally Fe-contaminated ingots, the distribution can be described by Scheil’s equation with an effective distribution coefficient of 2×10−5. The interstitial iron concentration was measured in the p-type ingots. In the Fe-contaminated ingot, it is almost constant throughout the ingot and constitutes about 50% of the total concentration, which is in conflict with the previous studies. Gettering had a large impact on the interstitial iron levels by reducing the concentration by two orders of magnitude. Considerable trapping was observed at crystal defects on as-cut wafers...
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Study of defects and impurities in multicrystalline Silicon grown from metallurgical Silicon Feedstock
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2008Co-Authors: Simona Binetti, J. Libal, Maurizio Acciarri, M. Di Sabatino, Heidi Nordmark, Eivind Øvrelid, John C. Walmsley, Randi HolmestadAbstract:Study of defects and impurities in multicrystalline Silicon grown frommetallurgical Silicon Feedstock
Gianluca Coletti - One of the best experts on this subject based on the ideXlab platform.
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Successful module hot spot testing of 120 ppma carbon contaminated Silicon Feedstock
2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), 2016Co-Authors: Kees Broek, N.j.j. Dekker, Gianluca ColettiAbstract:Several options for solar grade Silicon Feedstock have been investigated over the years to bring down the costs of Silicon wafers. Generally the resulting Silicon contains higher levels of impurities, the level depending on the refining processes. In this work wafers from a p-type mc-Si ingot made with Feedstock contaminated with 120 ppma of carbon have been processed firstly into solar cells and secondly into 60-cell solar modules. The focus here is to study the module reliability. It was demonstrated that a hot spot endurance test could be passed without any problems.
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Impact of Metal Contamination in Silicon Solar Cells
Advanced Functional Materials, 2011Co-Authors: Gianluca Coletti, P C P Bronsveld, Wilhelm Warta, Giso Hahn, Daniel Macdonald, Bruno Ceccaroli, Karsten Wambach, Nam Le Quang, Juan M. FernandezAbstract:Summary The impact on solar cell performance of transition metals like iron, chromium, nickel, titanium and co pper is the topic of this extended abstract. Each impurity has been intentionally added to Silicon Feedstock used to gr ow p-type directionally solidified multicrystalline Silicon i ngots. A state of the art screen print solar cell process ha s been applied to wafers cut from the bottom to the top of these ingots. Adding 50 ppmwt of iron or 40 ppmwt of nickel or chromium to Silicon Feedstock, results in comparabl e solar cell performances to reference uncontaminated material in the range 40% to 70% of the ingot height. Addition of 10 ppmwt of titanium dramatically reduces the efficien cy along the entire ingot. Impurities like iron, chromium an d titanium cause a reduction in the diffusion length. Nickel d oes not reduce the diffusion length. On the other hand affe cts strongly the emitter recombination reducing the sol ar cell performance significantly. Copper has the peculiari ty to impact both bulk recombination as well as emitter recombination. A model based on Scheil distribution of impurity ha s been derived to fit the degradation along the ingot. So lar cell performance has been modeled as function of base bulk recombination and emitter recombination. The model fits very well the experimental data and has been also successfully validated. Unexpectedly, the Scheil di stribution of impurity along the ingot leaves its finger-print also at the end of the solar cell process. A measure of impurit y impact has been defined as the level of impurity which cau ses a degradation of less than 2% up to 90% of the ingot height. The advantage of this parameter is that comprises t he different impurities physical characters in one sin gle parameter, easy to compare.
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Impact of metal contamination in multicrystalline Silicon solar cells: Case study for iron
2010 35th IEEE Photovoltaic Specialists Conference, 2010Co-Authors: Gianluca ColettiAbstract:The impact on solar cell performance of iron has been investigated. Iron has been intentionally added to Silicon Feedstock used to grow p-type directionally solidified multicrystalline Silicon ingots. A state of the art screen print solar cell process has been applied to wafers from the bottom to top of the ingot. Adding 50 ppmwt of iron to Silicon Feedstock, results in comparable solar cell performances to reference uncontaminated material, in the range 40 to 70% of the ingot height. Iron causes a reduction in the diffusion length, which decreases with the ingot height.
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impact of iron nickel and chromium in Feedstock on multicrystalline Silicon solar cell properties
24th European Photovoltaic Solar Energy Conference and Exhibition Hamburg Germany 21-25 september 2009. 4 p., 2009Co-Authors: Gianluca Coletti, R Kvande, H Habenight, C Swanson, Carlos Knopf, Wilhelm Warta, Lars Arnberg, P C P BronsveldAbstract:The effect of metal contamination in multicrystalline Silicon ingots on solar cell performance is investigated. Metal impurities have been added to the Silicon Feedstock and the solar cell performance has been compared to a reference uncontaminated ingot. A larger crystal defect density is observed in the top and in the bottom of the contaminated ingots with respect to the reference. Adding 50 ppmw of iron or 40 ppmw of nickel or chromium to the Silicon Feedstock in p-type ingots, the solar cell performances are comparable to the reference in the range of 40 to 70% ingot height. Addition of Fe, Ni or Cr does not only have a direct impact on the diffusion length, but also on the crystal growth and shunting behaviour.
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Effect of iron in Silicon Feedstock on p- and n-type multicrystalline Silicon solar cells
Journal of Applied Physics, 2008Co-Authors: Gianluca Coletti, R Kvande, Lars Arnberg, V. D. Mihailetchi, L. J. Geerligs, Eivind ØvrelidAbstract:The effect of iron contamination in multicrystalline Silicon ingots for solar cells has been investigated. Intentionally contaminated p- and n-type multicrystalline Silicon ingots were grown by adding 53 ppm by weight of iron in the Silicon Feedstock. They are compared to reference ingots produced from nonintentionally contaminated Silicon Feedstock. p-type and n-type solar cell processes were applied to wafers sliced from these ingots. The as-grown minority carrier lifetime in the iron doped ingots is about 1–2 and 6–20 μs for p and n types, respectively. After phosphorus diffusion and hydrogenation this lifetime is improved up to 50 times in the p-type ingot, and about five times in the n-type ingot. After boron/phosphorus codiffusion and hydrogenation the improvement is about ten times for the p-type ingot and about four times for the n-type ingot. The as-grown interstitial iron concentration in the p-type iron doped ingot is on the order of 1013 cm−3, representing about 10% of the total iron concentra...
Maxime Forster - One of the best experts on this subject based on the ideXlab platform.
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High efficiency UMG Silicon solar cells: impact of compensation on cell parameters
Progress in Photovoltaics: Research and Applications, 2015Co-Authors: Fiacre Rougieux, Roland Einhaus, Daniel Macdonald, Peiting Zheng, Julien Degoulange, Christian Samundsett, Kean Chern Fong, Andreas Fell, Maxime ForsterAbstract:High efficiency solar cells have been fabricated with wafers from an n-type Czochralski grown (Cz) ingot using 100% Upgraded Metallurgical-Grade (UMG) Silicon Feedstock. The UMG cells fabricated with a passivated emitter and rear totally diffused (PERT) structure have an independently confirmed cell efficiency of 19.8%. This is the highest efficiency reported for a cell based on 100% UMG Silicon at the time of publication. The current and power losses are analysed as a function of measured material parameters, including carrier mobility, lifetime and the presence of the boron–oxygen defect. Dopant compensation is shown to reduce both the minority carrier lifetime and mobility, which significantly affects both the current and voltage of the device. Copyright © 2015 John Wiley & Sons, Ltd.
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Compensation engineering for uniform n-type Silicon ingots
Solar Energy Materials and Solar Cells, 2013Co-Authors: Maxime Forster, Roland Einhaus, Bastien Dehestru, Antoine Thomas, Erwann Fourmond, Andres Cuevas, Mustapha LemitiAbstract:This paper addresses a major issue related to the use of upgraded-metallurgical grade Silicon for n-type solar cells. We show that n-type Silicon ingots, grown from Silicon Feedstock containing both boron and phosphorus, display a vertical net doping variation which is incompatible with high-yield production of high-efficiency solar cells. As a solution, we propose to use compensation engineering, by means of gallium co-doping, and demonstrate its potential to control the net doping along the ingot height. The resulting material exhibits high minority carrier diffusion length gratefully to compensation but degrades upon illumination due to the activation of the boron-oxygen defect. This latter degradation remains an important though not unsurmountable challenge for making high-efficiency n-type solar cells with upgraded-metallurgical grade Silicon.