The energetics, electronic structures, and optical properties of several neutral vacancies for γ-Si3N4 were studied based on density function theory within the generalized gradient approximation. The binding and formation energies of nitrogen vacancy were smaller than that of silicon vacancies, implying that nitrogen vacancy could be easily formed in γ-Si3N4. Corresponding density of states of different point vacancies was analyzed. It was concluded that the neutral silicon vacancies introduce the p-type carriers into the system, whereas single nitrogen vacancy led to an n-type semiconductor. The results showed indirect semiconductor of nitrogen vacancy for γ-Si3N4. The effects of optical properties were considered for single vacancies in γ-Si3N4. For silicon vacancies, the materials had much higher static dielectric constants than these of nitrogen vacancy and perfect γ-Si3N4. The single nitrogen vacancy for γ-Si3N4 had no effects on absorption and reflection in visible and infrared light. For silicon vacancy, it was significantly increased.

Effects of Single Vacancy on Electronic and Optical Properties for γ-Si3N4. Y.C.Ding, A.P.Xiang, X.J.He, X.H.Zhu, X.F.Hu: Chinese Journal of Chemical Physics, 2010, 23[2], 201