Semiconductor is an electronic device that conducts electricity after a certain amount of voltage applied to it. The resistance of a semiconductor decreases when the temperature increases and vice versa.
The conductivity of the semiconductor can be altered by introducing impurities to it.When two differently-doped regions exist in the same crystal, a semiconductor junction is created.
The behavior of charge carriers, which include electrons, ions and electron holes, at these junctions is the basis of diodes, transistors and all modern electronics. Examples of semiconductor silicon semiconductor, germanium semiconductor etc.
Semiconductor devices can display a range of useful properties, such as passing current more easily in one direction than the other, showing variable resistance, and sensitivity to light or heat. Because the electrical properties of a semiconductor material can be modified by doping, or by the application of electrical fields or light, devices made from semiconductors can be used for amplification, switching, and energy conversion.
A pure semiconductor, however, is not very useful, as it is neither a very good insulator nor a very good conductor. However, one important feature of semiconductors (and some insulators, known as semi-insulators) is that their conductivity can be increased and controlled by doping with impurities and gating with electric fields. Doping and gating move either the conduction or valence band much closer to the Fermi level, and greatly increase the number of partially filled states.
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