Semiconductors are a category of materials with an electrical conductivity that is intermediate between that of the good conductors and the insulators. The good conductors, which are all metals, have electrical resistivities down in the range of 10-6 W × cm. The insulators have electrical resistivities that are up in the range of 106 to as much as about 1012 W × cm. Semiconductors have resistivities that are generally in the range of 10-4 have to 104 W × cm. The resistivity of a semiconductor is strongly influenced by impurities, called dopants, that are purposely added to the material to change the electronic characteristics.
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