Silicon

Silicon (Latin: silicium) is the chemical element in the periodic table that has the symbol Si and atomic number 14. A tetravalent metalloid, silicon is less reactive than its chemical analog carbon. It is the second most abundant element in the Earth's crust, making up 25.7% of it by weight. It occurs in clay, feldspar, granite, quartz and sand, mainly in the form of silicon dioxide (also known as silica) and silicates (compounds containing silicon, oxygen and metals). Silicon is the principal component of glass, cement, ceramics, most semiconductor devices, and silicones, the latter a plastic substance often confused with silicon. Silicon is widely used in semiconductors because the semiconductor Germanium has a problem with reverse leakage current flow, and because its native oxide forms better semiconductor/dielectric interfaces than almost all other material combinations.

Production

Silicon is commercially prepared by the heating of high-purity silica in an electric arc furnace using carbon electrodes. At temperatures over 1900 °C, the carbon reduces the silica to silicon according to the chemical equation

Related Topics:
Carbon - Electrode - Chemical equation

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:SiO2 + C → Si + CO2

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Liquid silicon collects in the bottom of the furnace, and is then drained and cooled. The silicon produced via this process is called metallurgical grade silicon and is at least 99% pure.

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Using this method, silicon carbide, SiC, can form. However, provided the amount of SiO2 is kept high, silicon carbide may be eliminated, as explained by this equation:

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:2SiC + SiO2 → 3Si + 2CO

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In 2000, metallurgical grade silicon cost about $ 0.56 per pound ($1.23/kg).http://minerals.usgs.gov/minerals/pubs/commodity/silicon/760301.pdf.

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