Abstract
We report on a theoretical study of the electronic structures of freestanding nanowires made from narrow band gap semiconductors GaSb, InSb and InAs. The nanowires are described by the eight-band k.p Hamiltonians and the band structures are computed by means of the finite element method in a mixture basis consisting of linear triangular elements inside the nanowires and constrained Hermite triangular elements near the boundaries. The nanowires with two crystallographic orientations, namely the [001] and [111] orientations, and with different cross-sectional shapes are considered. For each orientation, the nanowires of the three narrow band gap semiconductors are found to show qualitatively similar characteristics in the band structures. However, the nanowires oriented along the two different crystallographic directions are found to show different characteristics in the valence bands. In particular, it is found that all the conduction bands show simple, good parabolic dispersions in both the [001]- and [111]-oriented nanowires, while the top valence bands show double-maximum structures in the [001]-oriented nanowires, but single-maximum structures in the [111]-oriented nanowires. The wave functions and spinor distributions of the band states in these nanowires are also calculated. It is found that significant mixtures of electron and hole states appear in the bands of these narrow band gap semiconductor nanowires. The wave functions exhibit very different distribution patterns in the nanowires oriented along the [001] direction and the nanowires oriented along the [111] direction. It is also shown that single-band effective mass theory could not reproduce all the band state wave functions presented in this work.
Highlights
INTRODUCTIONSemiconductor nanowires have attracted great attention due to their unique physical properties and potential applications in nanoelectronics, optoelectronics, and quantum electronics
Semiconductor nanowires have attracted great attention due to their unique physical properties and potential applications in nanoelectronics, optoelectronics, and quantum electronics.1–17With advances in the materials technology, high-quality semiconductor nanowire have been obtained through, for instance, molecular-beam epitaxy,18–20 metal-organic vapor phase epitaxy,21–23 and chemical vapor deposition.24–29 Due to their well organized crystal structures, relatively high carrier mobilities, small cross sections, and strong quantum confinement effects, III-V semiconductor nanowires have been employed to construct field-effect transistors,30–33 infrared photodetectors,34,35 light emission diodes,36,37 thermal electrical devices,38,39 laser devices,40,41 solar cells,42–45 and quantum devices.11–17,46–49125109-2 Luo, Liao, and XuAIP Advances 6, 125109 (2016)wildly adopted in the calculations for the nanowire band structures near the band extrema
The studies by Lassen et al have only be made for [111]-oriented InP and InAs nanowires with small cross-sectional sizes of 2.5 nm to 15 nm and are lack of the analysis of the conduction band properties and the spinor distributions in the band states, which can play an essential role in the understanding of the electronic properties of nanowires, especially, for those made from narrow band gap semiconductors
Summary
Semiconductor nanowires have attracted great attention due to their unique physical properties and potential applications in nanoelectronics, optoelectronics, and quantum electronics.. Wildly adopted in the calculations for the nanowire band structures near the band extrema Both narrow and large band gap nanowires grown along the [001] crystallographic direction have been studied based on 6 × 6 or 8 × 8 k.p Hamiltonians.. The purpose of this paper is to present a systematic study of the electronic structures of narrow band gap semiconductor GaSb, InSb and InAs nanowires oriented along the [001] and [111] crystallographic directions based on 8 × 8 k.p theory.
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