CdS掺Mg和Ni电子结构和光学性质的密度泛函理论研究

采用基于密度泛函理论的第一性原理赝势平面波方法,对闪锌矿结构CdS和CdS∶M(M=Mg,Ni)几何结构、能带结构、电子态密度和光学性质进行了系统的研究。几何结构研究对掺杂后体系晶格常量进行了优化计算,结果表明Mg和Ni原子掺入CdS后晶格常量均减小,晶格发生局部畸变。进一步研究了掺杂对体系电子结构的影响,能带结构和电子态密度分析表明由于Ni 3d电子的引入使CdS∶Ni成为半金属铁磁半导体,而Mg 3s电子的引入CdS∶Mg带隙变宽。另外,体系掺杂后,吸收系数分析表明掺杂导致吸收峰在可见光波长区域变化显著,且掺Ni导致吸收峰进一步向长波方向移动。

Density Functional Calculations of Electronic Structure and Optical Properties on Mg and Ni-Doped CdS

The structure, electronic properties and optical properties of zinc blende CdS and CdS∶M (M=Mg, Ni) were studied systemically from density functional theory (DFT) based on first-principles pseudopotential calculations. It showed that the M-doped material had a smaller lattice constant, which resulted in a local lattice distortion. The band structure and density of states (DOS) were further calculated, which indicated that CdS∶Ni was half metallic ferromagnetic semiconductor while CdS∶Mg was semiconductor with bigger band gap due to the introduction of Ni 3d and Mg 3s. The optical property was also studied from the calculated absorption coefficients, which showed that the absorption peaks changed obviously at the visible light wavelength area for the M-doped CdS. Furthermore, the absorption ranges was extended to even higher wavelength region for the Ni-doped CdS.