What is donor energy level?Explain.

Explanation

In case of n-type Si-crystal, the free electron produced by the donor atom (as-atom) revolves round the nucleus of the donor atom. It possesses a very small negative energy `(~~0.045 eV)` as it is revolving in the background of Si-crystal (having a high value of dielectric constant). All such electrons create an energy level just 0.045eV below the conduction band. The energy level created by such electrons is called donor energy level. As energy gap between donor energy level and conduction band is very small, electrons can easily cross it and the conductivity of the n-type semiconductor is greatly improved.