缺陷黄铜矿结构XGa_2S_4(X=Zn,Cd,Hg)晶体电子结构和光学性质的第一性原理研究

The first principle study of electronic and optical properties of defect chalcopyrite XGa_2S_4 (X = Zn, Cd, Hg)

采用基于密度泛函理论(DFT)的第一性原理超软赝势方法对缺陷黄铜矿结构XGa2S4(X=Zn,Cd,Hg)晶体的晶格结构、电学以及光学性质进行了对比研究.分析比较了它们的晶格常数、键长、能带结构、态密度、介电函数、折射率和反射系数等性质,并总结其变化趋势.结果表明:这三种材料的光学性质在中间能量区域(4eV—10eV)表现出较强的各向异性,而在低能区域(<4eV)和高能区域(>10eV)各向异性较弱.ZnGa2S4和HgGa2S4两种材料的折射率曲线在等离子体频率ωp处有一明显的拐点,反射系数在ωp处达到最大值后急剧下降.三种晶体的强反射峰均处于紫外区域,因此可以用作紫外光屏蔽或紫外探测材料.

The electronic and optical properties of the defect chalcopyrite XGa2S4 （X=Zn, Cd, Hg） compounds are studied based on the first-principle calculations. Its structural properties are consistent with the earlier experimental and theoretical results, and its electronic and optical properties are discussed in detail in this paper. The results indicate that the three compounds described hare exhibit an anisotropic behaviour in the intermediate energy range （4 eV–10 eV）, and an isotropic behaviour in the low（〈4 eV） or high（〉10 eV） energy range. The refractive index curves of ZnGa2S4 and HgGa2S4 have an inflection point at the plasma frequency ωp, and their reflectivity reaches a maximal value at ωp and then declines sharply. Moreover, the calculated optical properties indicate that these compounds can serve as shielding and detecting devices for ultraviolet radiation.