C掺杂β-FeSi2的电子结构和光学特性研究

摘要

By using the first principle pseudo-potential plane-wave method based on the density function theory,the geometrical structure,electronic structure and optical properties of C-doped β-FeSi2 are calculated and analyzed.The calculated results of the geometrical structure and electronic structure show that the lattice constants a and b decrease,while c has little change,the volume of lattice reduces; the band structure is still quasi-direct semiconductor and the band gap narrows,the direct and indirect band gap widths are not changed,the 3d density of state for Fe is weakened,but the density of state near the Fermi energy level is mainly composed of Fe-3d with C doped.Optical properties calculation indicates that after C doped,the static dielectric constant decreases,the peak of the imaginary part of dielectric function ε2 decreases and moves to a higher energy slightly,optical absorption coefficient decreases.These results offer theoretical data for design and application of optoelectronic material of β-FeSi2.%采用基于密度泛函理论的第一性原理赝势平面波方法,对C掺杂p-FeSi2的几何结构、能带结构、态密度和光学性质进行了理论计算.几何结构和电子结构的计算表明:C掺杂后使得β-FeSi2的晶格常数a和b减少,c变化不大,晶格体积减小；C掺杂后的 β-FeSi2能带结构仍为准直接带隙,禁带宽度变窄,直接带隙与间接带隙的能量差值不变,C的掺杂消弱了Fe的3d态电子,费米能级附近的电子态密度主要由Fe的3d态电子贡献.光学性质的计算表明:与未掺杂时相比,介电函数的实部ε1减少,虚部ε2的峰值减少并向高能方向有一微小的偏移,吸收系数有所降低.计算结果为β-FeSi2光电材料的应用和设计提供了理论指导.