Cai Yongqing, Zhang Gang, Zhang Yong-Wei
Institute of High Performance Computing, A*STAR, Singapore 138632.
Nanoscale. 2020 Oct 22;12(40):20890-20897. doi: 10.1039/d0nr05133k.
As one of the most intriguing elemental 2D materials beyond graphene, stanene is a unique material possessing strong quantum spin Hall effect and is promising for spintronics applications. Since most of these exotic phenomena are associated with the edge states of stanene and their responses under external stimuli, here, we first investigate the electronic and transport behavior of the edge states of stanene. Through examining the acoustic phonon-limited scattering of transporting carriers, we reveal a staggering behavior in the effective mass and mobility varying with the width of stanene nanoribbons. Remarkably, an opposite oscillating trend of the quantum confinement effect with respect to the electrons and holes is found and this trend is in sharp contrast to graphene. Moreover, through group-theory analysis, we further analyze the symmetry-permitted light absorptions and predict a much smaller band gap at Γ compared with other IV-group 2D materials like graphene and silicene, allowing for a red-shift of optical π-π* absorption in stanene. The presence of the narrow flat bands along the M-K path in stanene suggests appreciable density of states of low-energy carriers and a strong light-matter interaction for low-energy photons, which are beneficial for its applications in low-frequency optoelectronics.
作为除石墨烯之外最具吸引力的元素二维材料之一，锡烯是一种具有强量子自旋霍尔效应的独特材料，在自旋电子学应用方面颇具前景。由于这些奇异现象大多与锡烯的边缘态及其在外部刺激下的响应有关，在此，我们首先研究锡烯边缘态的电子和输运行为。通过研究输运载流子的声子散射受限情况，我们揭示了有效质量和迁移率随锡烯纳米带宽度变化的惊人行为。值得注意的是，发现了量子限制效应相对于电子和空穴的相反振荡趋势，且该趋势与石墨烯形成鲜明对比。此外，通过群论分析，我们进一步分析了对称允许的光吸收，并预测与石墨烯和硅烯等其他IV族二维材料相比，Γ点处的带隙要小得多，这使得锡烯中的光学π-π*吸收发生红移。锡烯中沿M-K路径存在窄平带，这表明低能载流子具有可观的态密度以及对低能光子有强光-物质相互作用，这有利于其在低频光电子学中的应用。
