硅基超晶格Ⅵ(A)/Si_6/SiO_2/Si_6/Ⅵ(A)的电子结构

Electronic Structure of Si-based Superlattice Ⅵ(A)/Si_6/SiO_2/Si_6/Ⅵ(A)

硅的有效光发射是硅基光电器件研究的一个关键问题,因此一直受到广泛的关注.本文采用第一性原理对新的硅基材料Ⅵ(A)/Sim/SiO2/Sim/Ⅵ(A)(m=6,Ⅵ(A)=O,Se)的能带结构、态密度和电荷密度等进行了计算研究.通过改变掺入Ⅵ(A)族原子氧和硒的对比,分析了SiO2层、不同的Ⅵ(A)族原子以及它们与最近邻Si原子的相互作用对硅基材料电子性质的影响.研究表明,在局域密度近似(LDA)下,O/Si6/SiO2/Si6/O结构在X点存在准直接带隙的特征,而Se/Si6/SiO2/Si6/Se在Γ点存在很小的直接带隙.

There is much interest in the Si-based efficient light emission material for its indispensability to the development of modern optoelectronics. In this paper,the band structures,density of states and charge density contours of Si-based superlattices Ⅵ （A）/Si6/SiO2/Si6 / Ⅵ （A） （Ⅵ（A） = O, Se） had been investigated with the first-principles calculations. The effect of SiO2, Ⅵ （A） atoms and the nearest Si atoms on the superlattice were also discussed. The present calculations, within the local density approximation （LDA）,reveal that the O/Si6/SiO2/Si6/O has a quasi-direct bandgap at X point, whereas the Se/Si6/SiO2/Si6/Se has a quite little gap at Г point.