Explain hole conduction in intrinsic semiconductors.

Explanation

Pure semiconductors are called intrinsic semiconductors.At low temperature, velency band is filled with electrons and conduction band is empty. Hence it acts as an insulator at low temperature.
As temperature increases electrons in valence band get energy and jumps into the conduction band crossing the forbidden band. At their places in the valency banda vacancy is created.
This vacancy of electron in the valency band is called a hole.Hole has positivecharge and move only in the valency band, giving hole current.
In this Fermi-energy level will be at the middle of the forbidden band.