表面钝化硅纳米线的能带结构

采用第一性原理的方法计算了不同尺寸的(100)硅纳米线在H饱和及F饱和下的电子结构.计算结果表明,F饱和与H饱和的(100)硅纳米线均为直接禁带半导体,但F饱和硅纳米线的禁带宽度和价带有效质量都远小于H饱和硅纳米线,这一现象可用价带顶的σ-n杂化效应来解释.计算结果还表明,H或F饱和的(100)硅纳米线的极限--硅单原子链则表现为间接带隙半导体,文中对这一现象进行了分析和讨论.

Band Structures of Si Nanowires with Different Surface Terminations

(100) silicon nanowires (SiNW) with different sizes and different surface terminations are studied with first-principles calculation.The results show that the one dimensional band structures of (100) SiNW with H and F terminations are both direct bandgap semiconductors,but SiNWs with an F termination have a smaller band gap and valence effective mass than SiNWs with an H termination.This can be interpreted via the σ-n mixing effect,i.e., the non-bonding 2P electrons (n) of F atoms produce an important orbital mixing with the σ valence electrons.We also predict from the calculations that the extreme of (100) SiNW-a 2×2 helical Si atom chain- is an indirect bandgap semiconductor.This prediction is explained at the end of this paper.