Ab initio study on intrinsic defect properties of germanium nitride considered for gate dielectric

First-principles calculations based on density-functional theory and local-density approximation were carried out to investigate intrinsic defect properties in β-Ge3N4. It was found that nitrogen vacancies are the main source of intrinsic defects in Ge3N4 due to their low formation energy. The N vacancies might become charge trapping centers since they induce energy levels near the Ge conduction band edge and in the middle of the Ge3N4 band gap. The formation energy of intrinsic defects in Ge3N4 is sensitive to N chemical potential, and N-rich ambient is favorable to reduce the concentration of N vacancies.