点缺陷对单层MoS2电子结构及光学性质的影响研究

采用基于第一性原理的贋势平面波方法，对不同类型点缺陷单层MoS2电子结构、能带结构、态密度和光学性质进行计算。计算结果表明：单层MoS2属于直接带隙半导体，禁带宽度为1.749ev,V-Mo缺陷的存在使得MoS2转化为间接带隙Eg=0.671eV的p型半导体，V-S缺陷MoS2的带隙变窄为Eg=0.974eV，S-Mo缺陷的存在使得MoS2转化为间接带隙Eg=0.482eV； Mo-S缺陷形成Eg=0.969eV直接带隙半导体，费米能级上移靠近价带。 费米能级附近的电子态密度主要由Mo的4d态和s的3p态电子贡献。光学性质计算表明：空位缺陷对MoS2的光学性质影响最为显著，可以增大MoS2的静态介电常数、折射率n0和反射率，降低吸收系数和能量损失。

Effect of point defects on Electronic Structure and Optical

The Electronic Structure, energy band structures, density of states and optical properties of monolayer MoS2 with point defects have been calculated by density functional theory (DFT) of the first-principles pseudo potential method wave method. The calculated results show that monolayer MoS2 is a direct semiconductor with the band gap of 1.749ev, monolayer MoS2 with the point defect of V-Mo is an indirect p type semiconductor with the band gap of 0.671eV, the band gap of monolayer MoS2 with the point defect of V-S reduces to 0.974ev, monolayer MoS2 with the point defect of S-Mo is indirect semiconductor with the band gap of 0.482eV, monolayer MoS2 with the point defects of Mo-S is a direct semiconductor with the band gap of 0.969eV and the Fermi energy level shift near the valence band. The density of state near the Fermi energy level is mainly composed of Mo-4d and S-3p.Optical properties calculation indicates that the vacancy defects is the most significant on the optical properties of the four kinds of point defects. The vacancy defects increase the dielectric function, the complex refractive index and the absorption index, and decrease the loss function and the loss function.