(n,n)扶椅型单臂ZnO纳米管的第一性原理

First-Principle study of the (n,n) armchair single-walled ZnO nanotubes

采用基于密度泛函理论的第一性原理计算方法系统研究了(n,n)扶椅型单臂ZnO纳米管的电子结构和属性。能量计算结果显示(n,n)扶椅型单臂ZnO纳米管的结合能都是负的,表明扶椅型单臂ZnO纳米管在基态下可稳定存在。当扶椅型ZnO纳米管直径增大,体系基态能量减小,ZnO纳米管体系趋于更加稳定的状态。其次,能带结构计算结果揭示扶椅型ZnO纳米管为直接宽带隙半导体材料,禁带宽度大于ZnO体材料的值,纳米管的整个价带随着纳米管管径的逐渐增加而被明显展宽,纳米管的价带向低能方向出现了明显的漂移现象。另外,在ZnO纳米管价带顶部出现了由表面效应引起的缺陷态能级。光学属性计算结果显示,吸收光谱发生了蓝移现象,计算的纳米管吸收带边对应于光谱的紫外波段,表明(n,n)扶椅型单臂ZnO纳米管是一种很有前途的紫外半导体发光材料。

Using the first-principle based on density function throry （DFT）,the electronic structures and properties of （n,n） armchair single-walled ZnO nanotubes （NTs）are investigated.The energy calculated results show that the binding energy is negative for the （n,n） single-walled ZnO NTs and can exist stably.And with the increased diameter of ZnO NTs,the energy of ground state can gradually decrease and the systems of ZnO NTs tend to be more stable.The calculated electronic results indicate that the （n,n） single-walled ZnO NT is a direct wide-gap semiconductor,the value of gap is significantly larger than bulk ZnO material.The whole valence bands are spread and drift to low-energy direction with the increase of the ZnO NTs diameter,and the defect energy levels emerge on the top of the valence bands.The optical calculated results reveal that the absorption spectrums take on obvious blue shift and the edge of absorption band corresponds to ultraviolet band,which the （n,n） single-walled ZnO NTs can be applied to ultraviolet semiconductor system.