Semiconductors are used in electric circuits. It is capable of conducting electricity and is an essential part of most electrical circuits.  

A semiconductor has a conductivity between that of an insulator and that of most metals.

This is due to either the addition of an impurity or because of temperature effects.

The reason why they are important is because they are essential components in most electronic circuits, such as silicon.

Basically, a semiconductor can conduct electricity and its conductance can vary depending upon the current or voltage applied to a control electrode, or on the intensity of irradiation by infrared, visible light, ultraviolet, or X rays.

Did you know that vacuum tubes were used prior to semiconductors? Find out why they were replaced on the next page.

A block of semiconductors becomes useful when it is doped and used to create a p-n junction. Doping alters the conductivity of a semiconductor and the junctions make it possible to use them for various purposes such as rectification and amplification.

Prior to semiconductors, vacuum tubes were used but these were bulky, costlier and dissipated a lot of heat.

An advantage of semiconductors is that they can be oxidised in order to form a high dielectric layer which can as a protection layer, mask and gate oxide in MOS transistors, which are the building blocks of today’s digital electronics.