半导体Si和GaAs的GW近似能带结构与BSE吸收光谱的研究

基于密度泛函理论,采用平面缀加波的广义密度近似的PBE泛函和准粒子近似的GW方法对典型的半导体硅Si和砷化镓GaAs的能带结构进行了研究;同时研究了Si和GaAs的光吸收谱,并利用多体微扰理论的BetheSalpeter方程(BSE)进行了修正。计算结果表明,准粒子近似的GW方法对Si和GaAs的能隙预测结果和实验值符合较好,考虑了电子—空穴对激子效应的GW-BSE多体微扰方法计算的Si和GaAs的介电函数吸收谱与实验谱符合最佳;研究说明激子效应在半导体光谱性质分析方面十分重要。

Electronic Structure and Optical Absorption of Si and GaAs by GW Aproximation and BSE Calculation

Based on the density function theory(DFT),the band structures of semiconductors Si and GaAs were calculated by the Perdew-Burke-Ernzerhof(PBE)function and corrected by the GW method of quasi-particle approximation,using the full-potential projected augmented wave(PAW)method.Then,the optical absorptions of Si and GaAs were presented by DFT and corrected by the BetheSalpeter equation(BSE)of many-body perturbation theory. The calculations indicate that the band gaps obtained by the GW method conform to the experimental values better than DFT results,and the electron-hole interaction significantly affects the optical absorption of Si and GaAs. The BSE results show that the excitonic effect is important in the research on the optical absorption of semiconductor.