摘要
基于密度泛函理论的第一性原理计算,研究了闪锌矿Mg_xZn_(1-x)Se合金的稳定性、电子结构和光学性质.研究结果表明,闪锌矿ZnSe和Mg_xZn_(1-x)Se合金都为直接带隙半导体,Mg_xZn_(1-x)Se合金的带隙宽度Eg和形成能Eb分别可以由Eg=1.30+1.34x和Eb=-1.48+0.60x-0.27x^2进行估计.同时,Mg_xZn_(1-x)Se合金的价带顶主要取决于Se 4p和Zn 3p态电子的相互作用,而其导带底则主要由Zn4s、Zn 3p以及Se 4s态电子共同决定.此外,随着镁掺杂系数x的逐渐增大,Mg_xZn_(1-x)Se合金的静态介电常数逐渐减小,而其吸收谱则出现明显的蓝移现象.研究结果为Mg_xZn_(1-x)Se合金在光电探测器方面的应用提供了重要的理论指导.
The structural stability, electronic structure and optical properties of zinc-blende MgxZn1-xSe alloys are determined using first-principles calculations based on the density functional theory. The results show that both the pure and Mg-doped ZnSe alloys display a direct band structure. The band gap Eg and formation energy Eb of MgxZn1-xSe alloys are able to be evaluated by the first order equation Eg=1.30+1.34x and the second order polynomial Eb=-1.48+0.60x-0.27x2, respectively. The top of valence band is mainly contributed by the Se 4p and Zn 3p states, while the bottom of conduction band is primarily occupied by the Zn 4s, Zn 3p and Se 4s states in MgxZn1-xSe alloys. Moreover, the static dielectric constant decreases and the optical absorption spectrum has a blue-shift obviously with the increasing Mg dopant composition x in MgxZn1-xSe alloys. The calculated results provide important theoretical guidance for the applications of MgxZn1-xSe alloys in optical detectors.
出处
《华中师范大学学报(自然科学版)》
CAS
北大核心
2017年第6期796-803,共8页
Journal of Central China Normal University:Natural Sciences
基金
湖北省自然科学基金项目(2015CFC784)