Thermodynamics and Kinetics of Direct Synthesis of Solar Grade Silicon from Metallurgical Silicon Wafer by Liquid Phase Migration in Solid Silicon
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- Kawanishi Sakiko
- Institute of Industrial Science, The University of Tokyo
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- Matsunaga Kunitoshi
- Institute of Industrial Science, The University of Tokyo
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- Yoshikawa Takeshi
- Institute of Industrial Science, The University of Tokyo
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- Morita Kazuki
- Department of Materials Engineering, The University of Tokyo
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Abstract
<p>We propose a process for the direct synthesis of solar grade Si from a metallurgical Si wafer focusing on the fact that its microstructure is composed of almost pure Si grains and grain boundaries enriched with impurities. Principally, heating a metallurgical grade Si wafer above its eutectic temperature and applying a temperature gradient allows the grain boundaries to be melted and causes them to migrate to the high-temperature direction. The liquid phases are finally terminated at the end surface, resulting in the upgrading of the Si and making it more favorable for solar cells. In the present paper, to determine the purification effect during the liquid phase migration process, thermodynamic assessment was performed using CALPHAD method. Liquid phase migration experiments were also conducted using synthetic MG-Si (Si-Fe alloy) to determine the reaction time for the process. A maximum migration velocity of 8.17 × 10−7 m/s was obtained at 1623 K, which allows the migration process to be accomplished within 3 min for a 150-μm wafer.</p>
Journal
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- MATERIALS TRANSACTIONS
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MATERIALS TRANSACTIONS 58 (11), 1571-1580, 2017
The Japan Institute of Metals and Materials
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Details 詳細情報について
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- CRID
- 1390282679229233664
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- NII Article ID
- 130006179825
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- NII Book ID
- AA1151294X
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- ISSN
- 13475320
- 13459678
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- NDL BIB ID
- 028602097
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- Text Lang
- en
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- Data Source
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- JaLC
- NDL
- Crossref
- CiNii Articles
- KAKEN
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- Abstract License Flag
- Disallowed