High-purity beta-SiC powder suitable for growing SiC single crystals was successfully synthesized from sol-gel precursors by carbothermal reduction. This was achieved through a two or three stage process that incorporated initial gasification, followed by gas phase reaction. To minimize the high loss that is typical of this process, and caused by the rate of evaporation in being faster than the gas phase reaction speed, the chemical structure of the precursor and heat treatment process were optimized. This found that a combination of tetraethyl orthosilicate and trimethyl phenylsilicate precursors, and a two-stage heat treatment, increases the production yield from 49.0% up to 84.4%. Furthermore, the purity of the beta-SiC was also increased to 99.7%, with a metallic impurity content of just 130 ppm.

Keywords: beta-SiC powder; Crystal growth; High purity; Carbothermal