Electronic structure and optical properties of Si–O–N compounds with different crystal structures
Abstract
In order to explore the relationship between crystal structure and optical properties, five Si–O–N compounds with different crystal structures, including: α-quartz SiO2, β-quartz SiO2, Si2N2O, α-Si3N4, β-Si3N4 were considered in the present work. Using density functional theory with the GGA+U method, their crystal structure, electronic structure, and optical properties have been systematically investigated. The electronic structure of α and β phases of SiO2 (or Si3N4) are similar, but with some subtle differences that can be attributed to the different local bonding structure, and the electronic structure of Si2N2O shows the fundamental features of the electronic properties of SiO2 and Si3N4. Based on the calculated results, it is found that the optical properties not only are determined by the components of the Si–O–N compounds, but also are determined by the microstructure of the Si–O–N compounds. These calculated results will be useful as reference data for analyzing the optical properties of more complicated SiOxNy compounds. According to this principle, one could design novel Si–O–N compounds for specific optoelectronic applications, via tuning the composition and crystal structure.