Dielectric property analysis for the different charge defects in SiO2 based on the first principles

In this paper, we establish the different defects species and the different charge states models, including the intrinsic and extrinsic defects, in the alpha-quartz system. The models for different defects have been optimized within the first principles. Furthermore, the formation energies for defect structures in the alpha-quartz system have been computed. We can deduce the easiest generated defect in the alpha-quartz system through the formation energies as a function of the Fermi level. From the simulation results, it is concluded that Al³⁺-Na⁺ defect is the most possible defect type at the low temperature, and then at the high temperature, the interstitial O^2- is the most possible defect type. Finally from the band structure, we also find thatalphathe interstitial O^2- and Al³⁺-Na⁺ defect are the shallow defect level in the energy band. And they become the very important accept defects in alpha-quartz.