Abstract
The electronic and optical properties of semiconducting silicon nanotubes (SiNTs) are studied by means of the many-body Green’s function method, i.e., GW approximation and Bethe–Salpeter equation. In these studied structures, i.e., (4,4), (6,6) and (10,0) SiNTs, self-energy effects are enhanced giving rise to large quasi-particle (QP) band gaps due to the confinement effect. The strong electron−electron (e−e) correlations broaden the band gaps of the studied SiNTs from 0.65, 0.28 and 0.05 eV at DFT level to 1.9, 1.22 and 0.79 eV at GW level. The Coulomb electron−hole (e−h) interactions significantly modify optical absorption properties obtained at noninteracting-particle level with the formation of bound excitons with considerable binding energies (of the order of 1 eV) assigned: the binding energies of the armchair (4,4), (6,6) and zigzag (10,0) SiNTs are 0.92, 1.1 and 0.6 eV, respectively. Results in this work are useful for understanding the physics and applications in silicon-based nanoscale device components.
Highlights
Silicon nanotubes [1,2,3,4,5] (SiNTs) have been demonstrated to be emerging materials with exclusive applications in micro- and nanoelectronics [6,7,8,9,10,11,12]
It has been identified that the self-energy effects are evident in the studied silicon nanotubes (SiNTs), giving rise to large QP band gaps, and the excitonic effects distinctly modify optical absorption properties, resulting in the formation of bound excitons with considerable binding energies
On the density functional theory (DFT)-local density approximation (LDA) level, the band gap of Si is calculated to be 0.61 eV, while at the GW level it turns out to be 1.17 eV, in good accordance to the band gap obtained from experiment [52]
Summary
Silicon nanotubes [1,2,3,4,5] (SiNTs) have been demonstrated to be emerging materials with exclusive applications in micro- and nanoelectronics [6,7,8,9,10,11,12]. Reduced electronic screening leads to the formation of excitonic resonances or strongly bound excitons with considerable binding energies. Many-body effects [18,19,20,21,22,23,24,25,26,27,28,29,30,31] are required to understand this kind of systems sufficiently, especially their single-particle excitation and optical absorption properties.
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