双壁硅纳米管电子结构与光学性质的研究

Study on electronic structure and optical properties of double-walled silicon nanotubes

本文中使用了基于密度泛函理论(DFT)的第一性原理方法,构建了手性指数(n,m)为(6,6),(10,10)硅纳米管管以及二者嵌套的双壁管结构并计算其能带结构、电子态密度以及光学反射谱与吸收谱.计算结果表明(6,6),(10,10)管表现出明显的半导体性,是直接带隙半导体.而双壁管相比于单臂本征硅纳米管其导带底与价带顶接触几乎发生交叠,表现出了轻微的金属性,其管内电子非局域性增强,导电能力提高.手性系数为(6,6)的硅纳米管对红外光、可见光以及紫外光都具有吸收能力.(10,10)管对于紫外光的吸收能力更加优秀但是对红外光的吸收能力减弱.(6,6)&(10,10)双壁管无论是吸收谱还是反射谱都最窄并出现了单峰.故可推测双壁管可作为检测一类特定范围波长的探测器的材料.

In this paper,the first-principle method based on density functional theory(DFT)is used to construct the chiral index(n,m)of(6,6),(10,10)silicon nanotube and their nested double-wall tube structures,and calculate the energy band structure,electron density,optical reflection and absorption spectra.The results show that(6,6)and(10,10)tubes are direct bandgap semiconductors with obvious semiconductor properties.Compared with the single wall silicon nanotubes,in the two-walled tube,the contact between the bottom of conduction band and the top of valence band almost overlaps showing slight gold properties.The non-locality of the electrons in the tube is enhanced,and the conductivity is improved.Silicon nanotubes with a chiral coefficient of(6,6)are capable of absorbing infrared,visible,and ultraviolet light.(10,10)tubes are better at absorbing ultraviolet light but less so at absorbing infrared light.Both absorption and reflection spectra of(6,6)and(10,10)double-walled tubes are narrowest and show unimodal peaks.Therefore,it can be speculated that the dual-wall tube can be used as a material for detecting a specific range of wavelengths.