拓扑缺陷对单壁碳纳米管电子结构及其光学光谱的影响

应用密度泛函理论计算了半导体型单壁碳纳米管(7,0)和(8,0)以及其发生镜像对称和非镜像对称Stone-Wales形变、形成异质结(7,0)-(8,0)情况下的能带结构、吸收光谱、反射光谱,并对计算结果进行了比较.研究发现:引入拓扑缺陷态后,碳纳米管的能带结构发生了明显的变化,费米能级在不同缺陷情况下移动方向不一致;碳管的吸收和反射明显减弱且吸收峰和反射峰在低能区发生红移现象;在光子能量约为E=13 eV处各碳管的吸收谱和反射谱中均出现一特征峰,并且在引入缺陷以后该特征峰向高能区移动.文章对计算结果进行了分析和探讨,可望利用这种拓扑缺陷的引入而产生的光电特性来设计碳管光电器件.

Effects of Topological Defects on the Electronic Structure and Optical Spectrum of Single-Wall Carbon Nanotubes

The energy band structures,optical absorption spectra and reflectivity of the semiconducting single-wall carbon nanotubes(7,0) and(8,0),with symmetrical Stone-Wales defects on(7,0) and symmetrical Stone-Wales defects on(8,0) and(7,0)-(8,0) SWCNT heterojunction were studied using the density functional theory,and the results were compared.It is shown that the energy band structures have changed obviously,and according to different kind of defects the Fermi energy levels were shifted in different direction.The absorption and reflectivity weakened obviously and red shift of absorption peak and reflectivity peak have occurred in the lower energy region,when the carbon nanotube contained topological defects compared to perfect single-wall carbon nanotubes.There was a distinct peak in the five carbon nanotubes at the photon energy of about E=13 eV,and the peak shifted to high energy region when the nanotube contained defects.The results were analyzed and discussed theoretically.The authors can take advantage of the photoelectricity property created by topological defect to design photoelectricity device.