CdSexS1-x电子学结构及光学性质的第一性原理研究

First-principles Investigation on Electronic Structure and Optical Properties of CdSexS1-x

CdSe是Ⅱ-Ⅵ族中重要的半导体材料,一定条件下可与CdS形成无限固溶体CdSexS1-x(0≤x≤1)。CdSexS1-x在薄膜太阳电池及光电器件等领域具有重要的应用,对CdSexS1-x的电子学结构和光学性质进行研究有助于进一步提高其在光电器件等方面的应用。基于第一性原理,采用平面波超软赝势方法,计算了CdSexS1-x的电子学结构及光学性质,并将计算结果与实验进行了对比。结果表明,CdSexS1-x的晶格常数随着Se组分的增加呈线性增大趋势,态密度向低能级方向移动,禁带宽度减小,光吸收边发生一定程度的蓝移。当Se含量为0.5时,CdSexS1-x的光折射、反射和能量损失最大。除了Se和S的比例为1∶1时CdSexS1-x所属晶系为三斜晶系,其他比例下均为立方晶系。理论计算结果与实验符合。

Cadmium selenide(CdSe)is a classicⅡ-Ⅵsemiconductor material.Most often,CdSe with CdS can form ternary alloys CdSexS1-x(0≤x≤1).CdSexS1-x has a large application in transparency electrode of CdTe thin-film solar cells and optoelectronic device.It is helpful to improve CdSexS1-x application value in photoelectric devices studying of its photoelectric properties.This paper calculates and analyzes the electronic structure and optical properties of CdSexS1-x ternary alloys with plane pseudo-potential mathod based on first-principles calculations.The calculated results are compared with the experimental results.The calculation results show that the lattice constant of CdSexS1-x ternary alloy crystal forming after Se substitutes S partly or wholly presents a tread of linear increase with the increase of Se content.Except Se∶S=1∶1 the crystal system of CdSexS1-x alloy with other ration does not change,forbidden gap decreases gradually and the peak value of state density gradually shifts towards the direction of high energy with the increase of Se content.In addition,the absorption edge exhibits a blue shift with Se concentration increasing.At the same time,reflectivity,loss-function and refractive index show their peak values when Se concentration x reaches 0.5.The calculation results are in good agreement with the experiment results.