First-principles investigation on the structural stability， electronic structure and optical properties of MgxZn1－xSe alloys
YU Zhiqiang1,2， ZHANG Changhua1， LIAO Honghua1， LI Shidong1， LANG Jianxun1
1.Department of Electrical Engineering， Hubei University for Nationalities， Enshi， Hubei 445000， China；2.School of Optical and Electronic Information， Huazhong University of Science and Technology， Wuhan 430074， China
Abstract：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.
2017, Vol. 51 
