Zn掺杂纤锌矿CdSe电子结构和光学性质的第一性原理研究

First-principles Study on Electronic Structure and Optical Properties of Zn-doped Wurtzite CdSe

采用密度泛函理论中的广义梯度近似平面波超软赝势方法,计算研究了不同浓度Zn原子掺杂纤锌矿结构CdSe的电子与光学性质。结果显示:随着Zn掺杂浓度的升高,纤锌矿Cd1-xZnxSe的体积在减小,形成能降低,掺杂越容易,稳定性变高;Zn掺杂引起导带底向高能方向移动,禁带宽度逐渐增加;掺杂后形成的Zn-Se键具有更大的密立根重叠布居数,表现出更强的共价性;体系的直接带隙宽度增加,导致光电子跃迁峰向高能方向发生蓝移;在紫外光区9.75 e V左右,掺杂体系的吸收强度达到最大,能量损失最小。

Band structures,density of states and optical properties of different concentration of Zn atom dopping wurtzite Cd1-xZnxSe are calculated and studied with plane-wave ultrasoft pseudopotential method based on first-principles density functional theory. After full relaxation,the calculations show that the volume of Cd1-xZnxSe increases,the formation energy of Cd1-xZnxSe reduces and the stability of Cd1-x ZnxSe become stronger with the increasing Zn impurity concentration. The Zn doping leads to the conduction band shift from low-energy area to high-energy area,and also band gaps of doped systems become wider. Zn-Se bond shows strong interaction,the Mulliken overpopulation is bigger,more covalent bonding character. The changing of gap induced blue shift of the optical transition peak. In the ultraviolet area around 9. 75 e V,the absorption of doping system strength achieve its greatest and least energy loss.