Effects of the DC bias in a molten silicon bath on its purification and hydrogenation by RF thermal plasma
✍ Scribed by M. Benmansour; S. Rousseau; D. Morvan
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 766 KB
- Volume
- 203
- Category
- Article
- ISSN
- 0257-8972
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✦ Synopsis
The aim of this work is the purification and the hydrogenation of metallurgical grade silicon for photovoltaic applications using a thermal plasma process. In addition to the plasma treatment, a DC bias of the liquid silicon was used to increase the kinetics of impurity extraction and hydrogenation reaction. On-line measurement by OES (Optical Emission Spectroscopy), ex-situ analysis by LIBS (Laser Induced Breakdown Spectroscopy) and ICP techniques demonstrated that elimination of metallic impurities and boron depends on the applied bias, and/or on the plasma gas composition. The DC bias was found to significantly increase the hydrogenation rate of liquid silicon, when it is attributed to electrochemical and/or chemical reactions in the electrical plasma sheath.