申論題

1. An unknown semiconductor has bandgap. of 1.36 eV. It is doped with donors. The effective density of states in the conduction band and the valance band are the same. The Fermi level is 0.2 eV below the bottom of the conduction band. Assume that 30% of total electrons are still in the donor states. Find the intrinsic carrier density in the material at T = 300 K. (20%)