Effects of n-Type Dopants on Electronic Properties in 4H-SiC

Based on first-principles calculations, we have investigated atomic and electronic structures of 4H-SiC crystal doped by N, P and As elements as n-type dopants. We have obtained the bond lengths of the optimization system, as well as the impurity levels, the band structure and the density of states. The results show that the higher impurity level above the Fermi level is observed when 4H-SiC doped by N with concentration as 6.25% in these dopants, and the band gap of 4H-SiC decreases while the doping concentration or the atomic number of dopant increases.