单壁碳纳米管吸附氧分子的电子输运性质理论研究

摘要

用基于第一性原理的密度泛函理论和非平衡态格林函数方法对(4,4)单壁碳纳米管及其吸附氧气分子情况下的平衡态和非平衡态电导性质进行了研究.发现在小于2 V的偏压下,系统对电压的增加呈现两种不同增长速率的电流响应,其中电压小于1.1 V时电流增加速率较大;而当电压大于该值后,电流对电压增加速率变缓.吸附的氧分子提供双重的作用,一方面氧分子提供的能级有利于电子隧穿中心散射区;另一方面氧分子的电子态会破坏碳管的平移对称性,从而降低电子对系统的透射能力.%Electron transport properties of (4,4) single wall carbon nanotube as well as the nanotube with oxygen molecule absorption, are investigated by using first principles analysis. The results show that electron current through the nanotube with oxygen molecule absorption system increases linearly under low bias ranging from 0 to 1. 1 V, while the bias is larger than 1. 1 V, the current through this system increases slowly. It is also shown that absorbed oxygen molecule brings two kinds of influence on the properties of electron transport; first, the oxygen molecular absorbed states afford new channels to electron transport and enhance the transmission. Second, the oxygen molecular absorbed states spoil the nanotube' s symmetry and enhance the electron scattering, so reduce the transmission.