Semiconductors are such materials in which the forbidden energy gap is small and the conduction takes place if some external energy is applied. Examples: Silicon, Germanium. The following figure shows the structure of energy bands in semiconductors.

Characteristics

The following are the characteristics of Semiconductors.

·        The Forbidden energy gap is very small.

·        The forbidden gap for Ge is 0.7eV whereas for Si is 1.1eV.

·        A Semiconductor actually is neither an insulator, nor a good conductor.

·        As the temperature increases, the conductivity of a semiconductor increases.

·        The conductivity of a semiconductor will be in the order of 102 mho-meter.