(c) Silicon
Silicon is the most abundant element in the earth’s crust after oxygen. Most of this
silicon exists as a component of silicate rocks and the element is not found as a simple
substance. Therefore, silicon is produced by the reduction of quartz and sand with
high-grade carbon using electric arc furnaces. Higher-grade silicon is obtained by
hydrogen reduction of SiHCl3, which is produced by the hydrochlorination of low purity
silicon followed by rectification. The silicon used for semiconductor devices is further
refined by the crystal Czochralski or zone melting methods. The crystal (mp 1410 oC) has
a metallic luster and the diamond type structure.