S掺杂纤锌矿ZnO晶体结构及电子性质的第一性原理研究

本文采用基于密度泛函理论的CASTEP模拟软件研究了本征纤锌矿ZnO、ZnS以及S掺杂ZnO所形成的纤锌矿ZnO1-xSx化合物的晶体结构及电子性质,计算结果显示纤锌矿ZnO1-xSx化合物的晶格常数随S的掺杂量的增加呈线性增加关系;S 3p态电子决定价带顶的位置,且基本上不因S含量的改变而发生移动;Zn 4s态电子决定导带底的位置,并随S掺入量的增加先向低能端移动而后向高能端移动。研究发现在ZnO1-xSx化合物中Zn和S主要靠共价键结合,而Zn和O主要靠离子键结合,随S掺入量的增加Zn-O离子键不断减少,而Zn-S共价键不断增加是造成ZnO1-xSx化合物带隙先减小而后增加的根本原因。

First-principles study of the crystal structures and electronic properties of S doped wurtzite ZnO

The crystal structures and electronic properties of wurtzite ZnO, ZnS and S doped ZnO have been investigated by using density--functional theory simulating package CASTEP. The calculation results indicate： the crystal constants increase with the quantity of S doping wurtzite ZnO; the top position of the valence band is determined by the S 3p electron state and it does not shift with the thickness of S--doping; the bottom position of the conduction band is determined by the Zn 4s electron state and it can shift to a lower energy position at first and then shift to a higher energy position with increasing S concentrations, the band gap of ZnO1-xSx is least when x is equal to 0.5. It is essential reason that the transformation from Zn--O eleetrovalent bond to Zn--S covalent bond with the thickness of S doping wurtzite ZnO.