含空位和杂质缺陷的闪锌矿电子结构的第一性原理计算

First-principle theory calculations of electronic structure of sphalerite with vacancy and impurity

采用基于密度泛函理论(DFT)的平面波超软赝势方法,研究硫空位、锌空位以及铁和镉杂质对闪锌矿电子结构的影响,分析空位和杂质对闪锌矿的价键结构、能带、态密度、差分电荷密度等的影响。计算结果表明:镉杂质缺陷导致闪锌矿的晶胞参数变大,而硫空位、锌空位和铁杂质均使闪锌矿的晶胞参数变小;硫空位使闪锌矿的带隙变窄,与硫空位相邻的4个锌原子的电荷明显低于其他锌原子的电荷;锌空位使闪锌矿的带隙变宽,费米能级向低能方向偏移,与锌空位相邻的4个硫原子的电荷明显低于其他硫原子的电荷;铁杂质使闪锌矿的带隙变宽,并在带隙中形成一个由铁的3d轨道贡献的杂质能级,费米能级向高能方向偏移;镉杂质对闪锌矿能带结构和态密度的影响较小,在闪锌矿价带-7.5eV处形成一个由镉的4d轨道贡献的能级,Cd—S键布居数下降,共价性减弱。

The electronic structures of sphalerite with Zn-vacancy,S-vacancy,Fe-impurity and Cd-impurity were calculated,respectively,using the ultra-soft pseudo-potential approach of the plane wave based on the density functional theory（DFT）,and their bond structure,band structure,density of states and the difference charge density were studied.The calculated results indicate that the Cd-impurity makes the lattice constant of sphalerite increase,but the S-vacancy,Zn-vacancy and Fe-impurity make the lattice constant decrease.The S-vacancy makes the band gap become narrow,and the Mulliken charge of Zn-atoms around the S-vacancy is lower than that of others.On the contrary,the Zn-vacancy makes the band gap become wide and the Fermi level moves to a low energy level,and the Mulliken charges of S-atoms around Zn-vacancy are lower than those of others.The Fe-impurity makes the band gap become wide and forms an impurity level in band gap,which consists of the 3d-electrons of the Fe atom,and the Fermi level moves to a high energy level.The Cd-impurity has a little effect on the band structure and density of states of sphalerite,and there is a level in -7.5 eV formed by the 4d-electron of the Cd atom.The population of Cd—S bond decreases and the covalence becomes weak.