Metallurgical and Materials Transactions B

, Volume 42, Issue 1, pp 37–49

Production of Solar-grade Silicon by Halidothermic Reduction of Silicon Tetrachloride

Authors

  • Kouji Yasuda
    • Institute of Industrial ScienceUniversity of Tokyo
    • High Performance Materials DepartmentOsaka Titanium Technologies Co., Ltd
  • Kunio Saegusa
    • Tsukuba Research LaboratorySumitomo Chemical Co., Ltd.
    • Institute of Industrial ScienceUniversity of Tokyo
Article

DOI: 10.1007/s11663-010-9440-y

Cite this article as:
Yasuda, K., Saegusa, K. & Okabe, T.H. Metall and Materi Trans B (2011) 42: 37. doi:10.1007/s11663-010-9440-y

Abstract

To develop a new production process for solar-grade Si, a fundamental study on halidothermic reduction based on the subhalide reduction of SiCl4 by Al subchloride reductant was carried out at 1273 K (1000 °C). Aluminum subchloride reductant was produced by reacting AlCl3 vapor with metallic Al. Silicon tetrachloride was reduced to Si in a gas-phase reaction by vapors of Al subchloride reductant. Silicon deposits produced in the halidothermic reduction were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray fluorescence (XRF). The Al content in the Si deposits was no more than 0.5 at pct. The Si deposits have a fibrous or hexagonal columnar morphology with diameters ranging from 100 nm to several tens of microns. The reaction was discussed by comparison with the results of the conventional aluminothermic reduction of SiCl4. Moreover, the halidothermic reduction reactions were analyzed from thermodynamical viewpoints. This study demonstrates the feasibility of a halidothermic reduction for producing solar-grade Si with high productivity.

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© THE MINERALS, METALS & MATERIALS SOCIETY and ASM INTERNATIONAL 2010