Si空位缺陷对β-FeSi2电子结构和光学性质的研究
Vacancies of Si Effects on Electronic Structure and Optical Properties of β-FeSi2

采用基于密度泛函理论的赝势平面波方法对含Si空位的β-FeSi2 缺陷体系的几何结构、能带结构、态密度和光学性质进行计算。结果表明，Si空位引起了晶格结构发生畸变，能带变窄，在价带与导带之间形成一个独立能带，费米面整体向上发生微小偏移，形成了P型半导体。对光学性质的研究发现，由于Si空位的介入使其邻近原子电子结构发生变化, 静态介电常数 (0)增大； 的第一峰的位置向低能端移动，吸收系数发生微小红移。
The defect geometry structure, band structure, density of states and optical properties are calculated in β-FeSi2 system and β-FeSi2 containing Si vacancies by density functional theory of potential plane wave method. The optimized results showed that Si vacancies result in the local lattice distortion, the narrower band gap and a new intermediate band between valence band and conduction band. The slight upward shift of Fermi surface due to Si vacancies leads β-FeSi2 to become a p-type semiconductor. The calculations of optical properties indicate that the electronic structure of adjacent atom is changed, the static dielectric constant ε1(0) increases, the highest peak of ε2 moves to a low-energy region and the tiny red shift of absorption coefficient takes place due to the Si vacancy