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Title:
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Solar-grade silicon by a direct route based on carbothermic reduction of silica: requirements and production technology
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Author(s):
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Geerligs, L.J.; Wyers, G.P.; Jensen, R.; Raaness, O.S.; Waernes, A.N.; Santén, S.; Reinink, A.; Wiersma, B.
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Published by:
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Publication date:
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ECN
Solar Energy
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1-9-2002
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ECN report number:
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Document type:
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ECN-RX--02-042
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Conference Paper
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Number of pages:
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Full text:
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4
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Download PDF
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Presented at: 12th Workshop on Crystalline Silicon Solar Cell Materials and Processes, Breckenridge CO, USA, 11-14 augustus 2002.
Abstract:
In the European projects SOLSILC and SPURT, a process is developed forthe production of solar grade silicon (SOG-Si) by carbothermic reduction
of silica, based on very pure raw materials. The purity of the raw materials
greatly reduces the requirements on purification of the silicon, from
dopants and other impurities. This paper reports the technology used
for the Si production, which is suitable for the available high purity
silica and carbon materials. It also reports results from the carbon
removal process, which brings the carbon content of the silicon from
several hundred ppmw to below 5 ppmw. Finally, it discusses experiments
on the allowable impurity concentrations in SOG-Si feedstock for directional
solidification. Segregation observed during directional solidification
is better than previously published, and allowable concentrations of
Fe and Ti are similar to what was previously published for monocrystalline
material by Westinghouse Corp.
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