Cu、Ni掺杂FeS_2电子结构与光学性质的第一性原理计算

First principle calculation of electronic structures and optical properties of copper and nickel doped FeS_2

采用基于密度泛函理论框架下的第一性原理平面波超软赝势法,研究Cu、Ni单掺杂与共掺杂体系中FeS_2的晶体结构、电子结构和光学性质。结果表明:掺杂后黄铁矿发生晶格畸变,晶格常数变大,掺杂在FeS_2禁带中引入杂质能级,使禁带变窄,费米能级上移进入导带,掺杂黄铁矿的态密度穿过费米能级,形成简并半导体,体系的导电率增强。光学性质计算表明:掺杂后介电函数虚部主峰、吸收系数和光电导率均出现红移、峰值减小。共掺杂后的光跃迁强度明显增强,可见光区范围内的光吸收系数和光电导率均增大,说明Cu-Ni共掺杂显著增强FeS_2对光的吸收以及光电转换效率。

The crystal and electronic structures, optical properties of copper and nickel mono- and co-doped FeS2 were studied by the first-principles plane-wave ultrasoft pseudopotential method with the generalized gradient approximation. The results show that, the lattice deformation of FeS2 occurs and the lattice parameters increase after doping. And the impurity energy level is introduced by Cu and Ni doping, which also leads to decrease of the band gap of FeS2. Fermi levels moves upward and into conduction band and density of states traverses the Fermi level, indicating that the doped FeS2 is degenerate semiconductor which shows stronger metallic characteristic and electrical conductivity. In addition, the doping results in peaks redshift and amplitudes decrease of imaginary part of dielectric function, absorption coefficient and conductivity. Optical transition is significantly enhanced and so are absorption coefficient and conductivity within visible region in the co-doping system. The photoabsorption capacity and photoelectrical efficiency of FeS2 are highly strengthened in Cu-Ni co-doping system.