基于密度泛函理论的第一性原理方法,计算了Al、Si单掺和两者共掺纤锌矿CdSe晶体的能带结构、态密度分布、电导率及吸收光谱。结果表明,Al单掺体系的形成能最小,掺杂最容易,且Al与晶胞原子间的键合作用更强,体系最稳定;Si单掺体系的形成能最大,掺杂最困难;两种单掺体系中,平行于和垂直于晶体超胞c轴的Si-Se键较长,布居值较小,共价键弱于Al-Se键;Al/Si共掺体系的电导率最大,Al单掺体系次之,Si单掺体系的电导率最小;掺杂后各个体系的最小光学带隙均变宽,同时吸收光谱向高能方向移动显著,吸收变弱。

By the first-principle method based on the density functional theory, the band structure, density of states, conductivity and absorption spectra of Al, Si single- or co-doped wurtzite CdSe are calculated. The results show that, as for the Al single doping system, the formation energy is the minimum and the doping process is the easiest, and the interaction between Al and other lattice cell atoms is strong and this system is the most stable. As for the Si single doping system, the formation energy is the largest, and the doping process is the most difficult. In these two single-doped systems, the population of Si-Se bond which is parallel or vertical to the c-axis of crystal supercell is smaller, but the bond length is longer. Its covalent bond is weaker than the Al-Se bond. The conductivity of the Al/Si co-doped system is the largest, that of the Al single-doped system is less, and that of the Si single-doped system is the smallest. After doping, the minimum optical band gap of each system becomes wider. Meanwhile, the absorption spectrum obviously moves towards the direction of high energy and the absorption becomes weak.