A Review of Intrinsic and Extrinsic Semiconductors.

Abstract

All the industrial and domestic electronic devices are made of a semiconductor. As the name suggests, semiconductor materials are neither good conductor nor good insulator of electrical current like Silicon and Germanium. Because of the very few current carriers (free electrons) available at the conducting shell, the specific resistance of the materials is comparatively higher than conductor and lower than that of an insulator.
Semiconductors are the perfect insulator at 0oK temperature, at higher temperature the materials are neither conductor nor insulator. The energy gap of semiconductors is lower as almost 1ev. At normal temperature, when electrons at valance shell gain energy, the gap between the valence band and conduction band is reduced. Very few numbers of electrons become available at conduction band, so a very low current flow could be expected.