Se掺杂ZnO的晶体结构和电子性质的第一性原理计算

First-principle study of the crystal structure and electronic properties of Se doped ZnO

本文采用基于第一性原理的密度泛函理论(DFT)平面波超软赝势方法,研究了纤锌矿ZnO及不同浓度Se掺杂ZnO合金的晶体结构和电子性质.在对Se掺杂结构优化的基础上对其进行了数值模拟计算,结果表明:ZnO_(1-x)Se_x晶格常数随着Se浓度的增大而近似呈线性增加;禁带宽度随着浓度的增大先减小后增大;价带顶的位置由Se-4p态电子决定,且基本不随浓度变化而变化,导带底的位置主要由Zn-4s态电子,且随Se掺杂浓度的增加先向低能段移动然后向高能段移动,这也是带隙先变小后变大的根本原因.

In this paper, we adopt the density functional theory（DFT）plane wave pseudopotential method to study the crystal structure and electronic properties for the different concentrations of Se doped into ZnO system. We optimize the structure of Se-doped ZnO and get the basis of numerical simulation. The results show that the lattice constants increase with the increasing quantity of impurity Se. The band gap grows narrower at first and then becomes wider with increasing Se concentration. The top position of the valence band is determined by the Se-4p electron states and it does not shift with the concentration of Se-doping. The bottom position of the conduction band is determined by the Zn-4s electron states and it can shift to a lower energy position at first and then shift to a higher energy position with increasing Se concentration, and it may be the essential reason of changes of the hand gap.