Semiconductors are substances with properties somewhere between them. ICs(integrated circuits) and electronic discrete components such as diodes and transistors are made of semiconductors. Common elemental semiconductors are silicon and germanium. Silicon is well-known of these. Silicon forms most of ICs.
There are some materials, which have neither good conductivity nor bad conductivity of electricity. They have a moderate range of electrical conductivity. The examples of such materials are germanium, silicon, carbon etc. As the conductivity of those materials lies between good conductors and insulators, and these materials are called semiconductors.
The atoms of semiconductor elements have exactly four valence electrons. Because of these four valence electrons, the semiconductor elements do have some special electrical characteristics and properties, which make them useful in using extensively in electronic circuit elements like diodes, transistors, SCRs, etc. Although a semiconductor has many physical properties, semiconductor name is given to this material because of its moderate electrical conductivity.
The resistivity of a semiconductor ranges from 10– 4 Ω – m to 0. 5 Ω – m. Where the resistivity of copper is about 1.7 × 10– 8 Ω – m in room temperature and resistivity of glass is about 9 × 1011 Ω – m. Copper is good conductor and glass is insulater.
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