点缺陷对CdS电子结构及光电特性的影响

The Effect of Point Defects on Electric Structure nd Optical-electrical Characteristic of CdS

采用密度泛函理论(DFT)的第一性原理超软赝势方法,计算了缺陷对CdS的电子结构和光电特性的影响。计算电子结构结果表明:CdS是带隙宽带为1.943eV的直接带隙半导体材料。价带主要由S 3p态电子贡献,导带主要由Cd 4d 5s和S3p态电子决定;V_(Cd)缺陷使得Cd_S在G点形成0.867e V的直接带隙;V_S缺陷使得CdS形成隙值为0.948e V的G-M点间接带隙;V_(S-Cd)缺陷使得CdS形成带隙值为0.966eV的K-G点间接带隙;V_(Cd-S)缺陷使得CdS转化为带隙值为0.438e V的n型直接带隙半导体。光学特性计算结果表明:缺陷均使得光学特性向低能方向偏移,同时引起介电常数增加,吸收系数增加,能量损失函数增加。计算结果为CdS光电特性的研发提供理论依据。

The electric structure and Optical-electrical characteristic of Cd S with point defects has been calculated by the debsity of functional theory of the first-principles pseudo potential wave method. The results of electric structure show that the energy band of Cd S is a direct semiconductor with the band gap of 1. 943 e V. The valence bands of Cd S are mainly composed of S 3p; the conduction band mainly composed of Cd 4d,Cd 5s and S 3p. The band gap of Cd S with the point defect of VCdreduces to a direct band gap of 0. 867 e V; the band gap of Cd S with the point defect of VS reduces to a indiect band gap of 0. 948 e V at the point of G-M; the band gap of Cd S with the point defect of VS-Cdreduces to a indiect band gap of 0. 966 e V at the point of K-G; the band gap of Cd S with the point defect of VCd-Sreduces to a diect n type semiconductor with the band gap of 0. 438 e V. The results of optical-electeical shows that the opticalelecteical moved to the direction of low energy,the static electric constant,the absorption,the loss function are increased. This result provide theoretical basis for the study of Cd S photoelectric characteristics.