局域体缺陷对石墨烯纳米带电子输运性质的影响

Transport Properties of Graphene Nanoribbons with Local Defects

利用递归格林函数方法研究存在体空位时之字型边界石墨烯纳米带的电子输运性质。研究结果表明,纳米带的电导对体空位非常敏感。当体系存在一个单原子空位时,电导受到明显的压制,完美的量子化台阶消失。同时在费米能处存在一个电导沟;当体系存在一个双原子空位时,电导压制亦非常明显,但电导沟存在于第一能带带边处。局域态密度分析结果显示,电导沟的形成是因为电子态局限在体空位周围,不能形成有效的电子通道,从而导致体系电导下降。另外,当存在两个随机分布的单原子空位时,体系的电导存在共振透射峰,透射峰的数目随着两个体空位之间的距离改变而改变。计算结果发现,体空位之间的距离每增加3个超原胞,电导将会增加一个透射峰。

We study the electronic properties of zigzag graphene nanoribbons（ ZGNRs） with body vacancies by using the recursive green＇s function method. We find the conductance is dependent sensitively on the effects of body vacancies. The conductance will be suppressed when an one- atom vacancies exists in the considered system and the quantized steps disappear. In addition,we find a transport gap at the Fermi energy（ E = 0e V）. When there exists a two- atom vacancy,conductance suppression becomes more visible and the transport gap develops close to the first energy band edges. The localization analysis shows the electronic states with energy E = 0e V are confined in a small range around the body vacancies and hence the transmission channel can not form. Consequently,the conductance drops rapidly. The situation becomes very different from above cases when two one- atom vacancies are distributed in the system. Our calculations indicate that there are some resonant transmission peaks near the Fermi energy and the number of the peaks will increase as the distance between the two vacancies increases.