First-principles investigation of point defects at 4H-SiC/SiO2 interface

The electronic structure of point defects at 4H-SiC/SiO2 interface was investigated by density functional theory. The results demonstrate characteristic features of the point defects at the SiC/SiO2 interface, including carbon vacancy, silicon vacancy, divacancy, and antisite pair. The density of states changes after the defects are introduced, and defects energy level appear in the band gap.The defects energy level leads to Fermi energy changes, while the density of states of defect energy level is greatly related to electronic state of several atoms in the vicinity of the defect. Formation energy is particularly high for Si vacancy, and is strongly related to the different chemical potential, which differs from C-rich to Si-rich interface.