Campos T, Toloza Sandoval M A, Diago-Cisneros L, Sipahi G M
Department of Physics, State University of New York at Buffalo, Buffalo, NY 14260, United States of America. Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo 13566-590, Brazil.
J Phys Condens Matter. 2019 Dec 11;31(49):495501. doi: 10.1088/1361-648X/ab38a1. Epub 2019 Aug 5.
Mainstream among topological insulators, GaSb/InAs quantum wells present a broken gap alignment for the energy bands which supports the quantum spin Hall insulator phase and forms an important building block in the search of exotic states of matter. Such structures allow the band-gap inversion with electrons and holes confined in adjacent layers, providing a fertile ground to tune the corresponding topological properties. Using a full 3D eight-band [Formula: see text] method we investigate the inverted band structure of GaSb/InAs/GaSb and InAs/GaSb/InAs multilayers and the behavior of the helical edge states, under the influence of an electric field applied along the growth direction. By tuning the electric field modulus, we induce the change of the energy levels of both conduction and valence bands, resulting in a quantum spin Hall insulator phase where the helical edge states are predominantly confined in the GaSb layer. In particular, we found that InAs/GaSb/InAs has a large hybridization gap of about [Formula: see text] and, therefore, are promising to observe massless Dirac fermions with a large Fermi velocity. Our comprehensive characterization of GaSb/InAs multilayers creates a basis platform upon which further optimization of III-V heterostructures can be contrasted.
在拓扑绝缘体中，GaSb/InAs量子阱是主流，其能带的能隙排列被打破，支持量子自旋霍尔绝缘体相，并且是寻找奇异物质态的重要组成部分。这种结构允许电子和空穴被限制在相邻层中时发生带隙反转，为调节相应的拓扑性质提供了丰富的条件。我们使用全三维八带[公式：见原文]方法，研究了在沿生长方向施加电场的影响下，GaSb/InAs/GaSb和InAs/GaSb/InAs多层结构的反转能带结构以及螺旋边缘态的行为。通过调节电场模量，我们诱导导带和价带的能级发生变化，从而形成量子自旋霍尔绝缘体相，其中螺旋边缘态主要被限制在GaSb层中。特别地，我们发现InAs/GaSb/InAs具有约[公式：见原文]的大杂化能隙，因此有望观察到具有大费米速度的无质量狄拉克费米子。我们对GaSb/InAs多层结构的全面表征创建了一个基础平台，在此基础上可以对比III-V族异质结构的进一步优化。
