论文标题
可调式带隙和各向同性光吸收来自含Bismuth的GAAS核心$ - $ $ shell and Multi $ - $ $ shell纳米线
Tunable band-gap and isotropic light absorption from bismuth-containing GaAs core$-$shell and multi$-$shell nanowires
论文作者
论文摘要
由于相关的直接带隙和高度可调的光电属性，基于GAAS基板的半导体核心$ - $ $ shell纳米线是许多光子，光伏和电子设备的构建块。选择合适的材料系统对于定制设计的纳米线至关重要，以优化设备性能。含有GAAS材料的二晶型材料是一类迫在眉睫的半导体，不仅可以对合金应变和电子结构进行精美的控制，而且还提供了抑制光子设备中内部损失机制的可能性。尽管在纳米线活动区域中掺入GABIAS合金的实验努力仍处于原始阶段，但对这种纳米线的光电特性的理论理解仅是基本的。这项工作阐明并量化了纳米线物理属性的作用，例如其几何参数和二晶型在设计光吸收波长和极化响应中的作用。基于数百万原子的GABIAS/GAAS CORE $ - $ shell和GAAS/GABIAS/GAAS/GAAS MULTI $ - $ shell纳米线的密集结合模拟，我们的结果预测，对吸收波长的大量调整，范围为0.9 $ $ m $ m $ m $ m至1.6 $ $ m $ M m，可以通过机器或nan anan nan nan anan anan dia来控制。应变曲线的分析表明拉伸特性导致价带状态中的明显的浅孔混合。这提供了实现对极化不敏感的光相互作用的可能性，这对于涉及放大和调制光的几种光子设备是可取的。此外，在低BI组成下，载体限制是准II型，这进一步扩大了这些纳米线对众多应用要求进行大型载体分离的适用性...
Semiconductor core$-$shell nanowires based on the GaAs substrate are building blocks of many photonic, photovoltaic and electronic devices, thanks to the associated direct band-gap and the highly tunable optoelectronic properties. The selection of a suitable material system is crucial for custom designed nanowires tailored for optimised device performance. The bismuth containing GaAs materials are an imminent class of semiconductors which not only enable an exquisite control over the alloy strain and electronic structure but also offer the possibility to suppress internal loss mechanisms in photonic devices. Whilst the experimental efforts to incorporate GaBiAs alloys in the nanowire active region are still in primitive stage, the theoretical understanding of the optoelectronic properties of such nanowires is only rudimentary. This work elucidates and quantifies the role of nanowire physical attributes such as its geometry parameters and bismuth incorporation in designing light absorption wavelength and polarisation response. Based on multi-million atom tight-binding simulations of the GaBiAs/GaAs core$-$shell and GaAs/GaBiAs/GaAs multi$-$shell nanowires, our results predict a large tuning of the absorption wavelength, ranging from 0.9 $μ$m to 1.6 $μ$m, which can be controlled by engineering either Bi composition or nanowire diameter. The analysis of the strain profiles indicates a tensile character leading to significant light-hole mixing in the valence band states. This offers a possibility to achieve polarisation-insensitive light interaction, which is desirable for several photonic devices involving amplification and modulation of light. Furthermore, at low Bi compositions, the carrier confinement is quasi type-II, which further broadens the suitability of these nanowires for myriad applications demanding large carrier separations...
