Analysis of the electronic structure of β-SiO2 intrinsic defects based on Density Functional Theory

Abstract

In order to characterize the effect of β-SiO2 intrinsic defects on the properties of the perfect structure, the electronic properties of the perfect β-SiO2 and its four typical intrinsic defects under the generalized gradient approximation (GGA) based on Density Functional Theory (DFT) were performed, and the defect formation energy, energy band, density of states (DOS) and differential charge density were calculated. The defect formation energy calculation results showed that interstitial defects were easier to form but less stable than vacancy defects. Meanwhile, the analysis of energy band and DOS indicated that the perfect and defective structures of β-SiO2 were indirect band gap insulators. Furthermore, the appearance of DOS at the Fermi level in the silicon interstitial structure and the energy band passing through the Fermi level indicated that the conductivity of the structure was improved. Moreover, the study of differential charge density illustrated charge transferred from silicon atoms to oxygen atoms, and Si-O covalent bonds with strong polarity were formed between silicon and oxygen atoms. Our studies could provide a theoretical basis for the study of the evolution of intrinsic defects and damages in ultra-precision machining such as ion beam figuring.