Nolan Michael, O'Callaghan Sean, Fagas Giorgos, Greer James C, Frauenheim Thomas
Tyndall National Institute, Lee Maltings, Prospect Row, Cork, Ireland.
Nano Lett. 2007 Jan;7(1):34-8. doi: 10.1021/nl061888d.
Band gap modification for small-diameter (approximately 1 nm) silicon nanowires resulting from the use of different species for surface termination is investigated by density functional theory calculations. Because of quantum confinement, small-diameter wires exhibit a direct band gap that increases as the wire diameter narrows, irrespective of surface termination. This effect has been observed in previous experimental and theoretical studies for hydrogenated wires. For a fixed cross-section, the functional group used to saturate the silicon surface significantly modifies the band gap, resulting in relative energy shifts of up to an electronvolt. The band gap shifts are traced to details of the hybridization between the silicon valence band and the frontier orbitals of the terminating group, which is in competition with quantum confinement.
通过密度泛函理论计算研究了使用不同物种进行表面终止对小直径（约1纳米）硅纳米线带隙的影响。由于量子限制，无论表面终止情况如何，小直径的硅纳米线都呈现出直接带隙，且随着线径变窄而增大。这种效应在先前关于氢化硅纳米线的实验和理论研究中已被观察到。对于固定的横截面，用于使硅表面饱和的官能团会显著改变带隙，导致相对能量偏移高达一个电子伏特。带隙的偏移可追溯到硅价带与终止基团前沿轨道之间杂化的细节，这与量子限制相互竞争。
