OsSi2电子结构及介电性能的第一性原理研究

采用基于密度泛函理论的第一性原理,研究了硅基异质外延的OsSi_2的电子结构和介电性能。结果表明,在1.010nm≤a≤1.030nm范围内,OsSi_2始终为间接带隙的能带结构,且带隙值随晶格常数a的增大而逐渐减小;当晶格常数a为1.020nm时,体系处于稳定平衡态,此时OsSi_2具有0.625eV的间接带隙能量值;OsSi_2的价带主要由Os的5d、5p和Si的3s、3p态电子构成,导带主要由Si的3s、3p和Os的5d、6s态电子构成;OsSi_2在外延稳定平衡态及其附近的介电函数实部和虚部变化趋近一致,与块体OsSi_2相比,OsSi_2在外延稳定平衡态下的介电函数曲线相对往低能区飘移,OsSi_2的介电峰减少且介电峰强度明显增强。

First-principles Study of the Electronic Structure and Dielectric Properties of OsSi2

The electronic structure and dielectric properties of semiconductor material OsSi₂ epitaxial growth on the Si(111) that the epitaxial relation is OsSi₂(101)//Si(111) with OsSi₂010]//Si011] are obtained by using the pseudo potentials plane wave method based on first principles methods. The calculated results show that OsSi₂ is an indirect semiconductor material, the band gap of OsSi₂ decrease with the increase of the lattice parameter a when the lattice parameter is between 1.010 nm with 1.030 nm. The system is in the stable conduction as well as OsSi₂ is an indirect semiconductor with the band gap of 0.625 eV when the lattice parameter is 1.020 nm. The valence bands of OsSi₂ are mainly composed of Os 5d,5p and Si 3s,3p, and the conduction bands of OsSi₂ are mainly composed of Si 3s,3p and Os 5d,6s. The calculated real part and imaginary part of dielectric function shows that the trend of change is similar on the whole between the epitaxial stable conditions and its neighboring points. However, the curves of epitaxial OsSi₂ drift toward low energy and the number of dielectric function peak decreases as well as the intensity becomes strong obviously.