First-principle calculation on the defect energy level of carbon vacancy in 4H--SiC

First, electronic structures of perfect wurtzite 4H--SiC were calculated by using first-principle ultra-soft pseudo-potential approach of the plane wave based on the density functional theory; and the structure changes, band structures, and density of states were studied. Then the defect energy level of carbon vacancy in band gap was examined by substituting the carbon in 4H--SiC with carbon vacancy. The calculated results indicate the new defect energy level generated by the carbon vacancy, and its location in the band gap in 4H--SiC, which has the character of deep acceptor. A proper explanation for green luminescence in 4H--SiC is given according to the calculated results which are in good agreement with our measurement results.