碳锗掺杂对硅纳米管电子结构和光电性质的影响

doi:10.15541/jim20140439

摘要/Abstract

摘要：

采用基于密度泛函理论的第一性原理计算, 研究了C/Ge掺杂对单壁扶手型硅纳米管电子结构和光电性质的影响。结果表明, 本征态和C/Ge掺杂的硅纳米管均属于直接带隙半导体, 其价带顶主要由Si-3p态电子构成, 而导带底则主要由Si-3p态电子决定。通过C掺杂, 可使硅纳米管的禁带宽度减小, 静态介电常数增大, 吸收光谱产生红移; 而通过Ge掺杂, 可使硅纳米管的禁带宽度增大, 静态介电常数减小, 吸收光谱产生蓝移。研究结果为硅纳米管在光电器件方面的应用提供了理论基础。

关键词: 第一性原理, 硅纳米管, 电子结构, 光电性质

Abstract:

The electronic structures and optoelectronic properties of C/Ge-doped single-walled armchair silicon nanotubes were determined by using first-principles calculations in the framework of density-functional theory. In particular, the calculated results indicate that both pure and C/Ge-doped silicon nanotubes display a direct band gap. The band gap is decreased firstly and then increased for the silicon nanotubes doped with C and Ge, respectively. Moreover, the upper of valence band is mainly contributed by the Si-3p states and the lower of conduction band is primarily occupied by the Si-3p states. The state dielectric constant is improved and the optical absorption shows a red-shifted for the C-doped silicon nanotubes, whereas the state dielectric constant is reduced and the optical absorption shows a blue-shifted for the Ge-doped silicon nanotubes. The results provide an useful theoretical guidance for the applications of single-walled armchair silicon nanotubes in optical detectors.

Key words: first-principles, silicon nanotubes, electronic structures, optoelectronic properties

中图分类号:

O471

余志强, 张昌华, 李时东, 廖红华. 碳锗掺杂对硅纳米管电子结构和光电性质的影响[J]. 无机材料学报, 2015, 30(3): 233-239.

YU Zhi-Qiang, ZHANG Chang-Hua, LI Shi-Dong, LIAO Hong-Hua. Electronic Structures and Optoelectronic Properties of
C/Ge-doped Silicon Nanotubes[J]. Journal of Inorganic Materials, 2015, 30(3): 233-239.

图/表 10

图1 单壁扶手型(6, 6)硅纳米管的径向截面图(a)和轴向截面图(b)

Fig.1 Radial section (a) and axial section (b) of (6, 6) single- walled armchair silicon nanotubes

表1 C/Ge掺杂单壁扶手型(6, 6)硅纳米管的晶胞参数

Table1 Lattice parameters of C/Ge-doped (6, 6) single- walled armchair silicon nanotubes

Model	(a=b)/nm	c/nm	D_Si-Si/nm	E_f/eV
Intrinsic	3.055	0.386	0.228	-
C-doped	2.948	0.376	0.226	-5.05
Ge-doped	3.099	0.388	0.231	-0.81

图2 本征单壁扶手型(6, 6)硅纳米管的能带结构图

Fig.2 Band structure of pure (6, 6) single-walled armchair silicon nanotubes

图3 本征单壁硅纳米管的总态密度图(a)和分态密度图(b)

Fig. 3 Total density of states (a) and part density of states (b) for pure single-walled armchair silicon nanotubes

图4 C掺杂图(a)和Ge掺杂图(b)掺杂硅纳米管的能带结构图

Fig. 4 Band structures of C-doped silicon nanotubes (a) and Ge-doped silicon nanotubes (b)

图5 C掺杂硅纳米管的总态密度图(a)和分态密度图(b, c)

Fig. 5 Total density of states (a), part density of states (b, c) for C-doped silicon nanotubes

图6 Ge掺杂硅纳米管的总态密度图(a)和分态密度图(b, c)

Fig. 6 Total density of states (a), part density of states (b, c) for Ge-doped silicon nanotubes

图7 硅纳米管的径向面电荷密度分布图

Fig. 7 Radial charge density distribution of silicon nanotubes pure (a), C-doped (b) and Ge-doped (c)

图8 C/Ge掺杂前后硅纳米管的复介电函数实部图(a)和虚部图(b)

Fig. 8 Real part (a) and imaginary part (b) of dielectric function for pure and C/Ge-doped silicon nanotubes

图9 C/Ge掺杂前后硅纳米管的吸收光谱图

Fig. 9 Absorption spectra of pure and C/Ge-doped silicon nanotubes

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