Abstract

Elemental silicon, a metal, does not occur in nature, but as the oxide is a constituent of various rocks comprising about 28% of the earth’s crust. There are three naturally occurring stable isotopes and several radioactive ones. Except at very high pressures, silicon has a diamond cubic structure and is a semiconductor.

High purity silicon is used primarily for its semiconducting properties and is the primary constituent of silicon diodes, transistors, and integrated circuits. Ordinary metallurgical-grade silicon is made by reducing quartz sand with coke in an electric furnace. That silicon may then be used to produce a silicon compound such as a chlorosilane that is relatively easy to purify. After purification, the compound is reduced to give high purity, semiconductor-grade silicon, where most of the impurities are in the parts per billion range. Purification methods are discussed and properties of the electronics-grade silicon given. Health and safety data and new uses are detailed.