Explain the .Conduction band. .Valence band. and .Energy gap. in semiconductors.

Explanation

Conduction band : The band lying next to the valence band which may be partially filled at room temperature but completely empty at 0K is called conduction band. Electron in this band contribute to the conduction process. Hence the conductivity of a solid depends on the availability of electrons inthe conduction band. Electrons in this band is called conduction electrons.
Valence band : The highest energy band which is completely or partially filled at absolute zero (0 K) is called valence band.
Electrons in this band are called valence electrons. They are loosely bound to the nucleus. They are easily detachable from the nucleus.
Energy gap : The separation between the top of the valence band and bottom of the conduction band is called energy gap. This is so called because electrons cannot possess these energy levels in the given solid.