Question

What is a Fermi energy level? What is its position in case of an intrinsic semiconductor?

Answer 1

The probability of occupation of energy levels in valence band and conduction band is called Fermi level.

In intrinsic or pure semiconductor, the number of holes in valence band is equal to the number of electrons in the conduction band. Hence, the probability of occupation of energy levels in conduction band and valence band are equal. Therefore, the Fermi level for the intrinsic semiconductor lies in the middle of forbidden band.