Oxygen distribution on a multicrystalline silicon ingot grown from upgraded metallurgical silicon

Sabatino, Marisa Di; Binetti, S.; Libal, Joris; Acciarri, M.; Nordmark, Heidi; Øvrelid, Eivind

doi:10.1016/j.solmat.2010.09.013

Cited by 29 publications

(18 citation statements)

References 20 publications

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“…Kvande et al 33 showed that at slow cooling rates mc silicon ingots have higher oxygen concentration and lower minority carrier lifetime. The effect of oxygen on a new generation of silicon feedstock materials, named UMG (upgraded metallurgical grade), was investigated by Di Sabatino et al 34. They showed the effect of heat treatments to reduce and control the oxygen distribution on mc silicon ingots for solar cells.…”

Section: Improved Crystallization Methodsmentioning

confidence: 99%

“…They showed the effect of heat treatments to reduce and control the oxygen distribution on mc silicon ingots for solar cells. A solar cell efficiency reduction by 1–3% absolute value was estimated on ingots made from UMG feedstock with high oxygen concentration 34. Iron and chromium are fast diffusing impurities in silicon and introduce allowed energy states close to the middle of the silicon bandgap.…”

Section: Improved Crystallization Methodsmentioning

confidence: 99%

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Defect generation, advanced crystallization, and characterization methods for high‐quality solar‐cell silicon

Sabatino

Stokkan

2012

Physica Status Solidi (a)

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Silicon is the dominant material for production of solar cells. Research work constantly aims at improving the quality of the silicon materials to achieve higher solar‐cell conversion efficiencies. It has been demonstrated that defects and impurities, often rising during the silicon ingot production and due to the presence of impurity sources throughout the silicon solar‐cell value chain (e.g. silicon feedstock, crucible and coating, furnace atmosphere, etc.), have a detrimental effect on device performances. Crystallization is the first step in the solar‐cell value chain. During crystallization, crystal defects, such as grain boundaries and dislocations, develop, and impurities, such as dopants and metals, distribute. By controlling the process, we can also control the defect formation and impurity segregation. In this study, we review some of the work carried out at NTNU to understand the role of defects and impurities on materials properties. Specifically, we report on some of the work done on defects, crystallization, and characterization.

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Section: Improved Crystallization Methodsmentioning

confidence: 99%

Section: Improved Crystallization Methodsmentioning

confidence: 99%

Defect generation, advanced crystallization, and characterization methods for high‐quality solar‐cell silicon

Sabatino

Stokkan

2012

Physica Status Solidi (a)

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“…Grain boundaries are also preferred sites for impurity precipitation, including light elements, carbon, oxygen and nitrogen , and transition metal impurities . Precipitates may play an important role as precursors for post‐growth dislocations, for instance by forming stress concentration centers due to different thermal expansion coefficient or lattice misfit.…”

Section: Introductionmentioning

confidence: 99%

The impact of oxygen precipitation on dislocation generation at small angle grain boundaries during seed‐assisted directional solidification of silicon

Autruffe

Kivambe

Arnberg

et al. 2015

Physica Status Solidi (a)

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We have investigated the source of dislocations generated during growth and subsequent cooling of quasi‐monocrystalline silicon. Bi‐crystals of silicon separated by ∼5.2° tilt small angle grain boundary have been directionally solidified at two different pulling rates, i.e., 3 and 13 μm s−1. We observe higher density of grain boundary‐associated dislocations at the ingot pulled at a lower rate. This observation is explained by the impact of oxygen precipitation behavior at the grain boundary.

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“…The most commonly used material in photovoltaic cells is multicrystalline silicon (multi-Si) [23]. Since 2005, multi-Si maintained relatively constant market shares [24] until 2009 [25], competing directly with mono-Si. From 2009 to 2016 it increased its share, but the trend stopped in 2017 [20], when mono technology started to grow relatively after manufacturers began switching towards lower processing cost and higher yield diamond-wafer technology while processing equipment suppliers began offering tools for low-cost high-efficiency cell designs [1].…”

Section: Source: Ipcc [2]mentioning

confidence: 99%

“…Impurities such as boron and phosphorus, in small amounts, are desirable to ensure the electrical characteristics necessary for the production of energy in the silicon solar cell. Other impurities, however, have detrimental effects on solar cells, leading to the formation of defects and favoring the formation of dislocations, which act as deep energy level centers of recombination affecting the mechanical and electrical properties, as well as diminishing the performance [25], [86], [87].…”

Section: Impurities Effects On C-si Solar Cell Performancementioning

confidence: 99%

Evaluation of impurities in the Brazilian solar grade silicon and LeTID investigations in p-type multi-Si

Knob¹

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KNOB, D. Evaluation of impurities of the Brazilian solar grade silicon and LeTID investigations in p-type multi-Si. 2019. 119 p. Thesis (Doctorate in Nuclear Technology-Materials)-Instituto de Pesquisas Energéticas e Nucleares-IPEN-CNEN/SP. São Paulo The cost reductions and the environmental benefits aligned with global concerns about climate change have made solar photovoltaic technology the most installed source of energy in the power sector worldwide. Brazil has the largest know reserves of silicon in the world. Therefore, there is a huge potential for developing a national technology for purifying and manufacturing silicon wafers within an increasingly competitive and efficient photovoltaic industry. The IPEN initiative of investigating the production of metallic silicon and metallurgical route purification required a characterization of samples in different stages of production from quartz to wafer and understanding the characterization methods for silicon wafers taking into account the main defect mechanisms such as light-induced degradation. Metalic silicon is produced in IPEN via magnesiothermal reduction through acid leaching to form a metallurgical grade silicon with relatively low impurities. One more acid leaching step resulted in a specific ultrametallurgical grade silicon. The same acid leaching was processed in a commercially available Brazilian-made metallurgical grade silicon produced via carbothermal reduction. All samples impurities was measured by ICP-OES. The result is a material with ultra-metallurgical grade silicon content with excess of B and P. While wafer characterization was studied, an extensive investigation was taken on LeTID, which causes remain unknown, at Institute for Energy Technology, Norway. Neighboring high performance mc-Si p-type wafers were tested in different firing process conditions. The effects was investigated in terms of defects activation and a corresponding lifetime degradation and recovery at illuminated annealing. A sample with almost fully suppressed LeTID is shown. A new method have been proposed to separate Boron Oxygen-Light Induced Degradation effects of LeTID, enabling to measure even where it was thought to be fully suppressed. New models for LeTID defect formation and suppression are proposed. Both silicon purification and light-induced degradation characterization in mc-Si studies shows a wide range of research on new production routes that may require tailored processes of crystallization and solar cell manufacturing such as gettering and firing.

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Oxygen distribution on a multicrystalline silicon ingot grown from upgraded metallurgical silicon

Cited by 29 publications

References 20 publications

Defect generation, advanced crystallization, and characterization methods for high‐quality solar‐cell silicon

Defect generation, advanced crystallization, and characterization methods for high‐quality solar‐cell silicon

The impact of oxygen precipitation on dislocation generation at small angle grain boundaries during seed‐assisted directional solidification of silicon

Evaluation of impurities in the Brazilian solar grade silicon and LeTID investigations in p-type multi-Si

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