增强型GaSb/Si/InAs异质结量子器件输运及其内电场下拓扑绝缘态的研究

GaSb/InAs, an III-V semiconductor heterostructure with high mobility, can achieve ultrafast electron conduction and high tunneling probability. However, it is a great obstacle for the application in GaSb/InAs heteroctructure owing to its high sub-threshold swing and bipolar effect. A novel nanostructure of GaSb/Si/InAs heteroctructure is proposed in our study to resolve the deficiency in GaSb/InAs heteroctructure by reconstructuring device sturcture, energy band regulation, and novel quantum state. Firstly, by performing first-principles calculation, we study the relationship among the band structure, embedded Si thickness, and interfacial stress, in order to find the structure with type-II energy band structure and low tunneling barrier. Secondly, it is significantly to discovery the synergistic effect of the internal electric field and the stress on the band structure, which is key factor in exploring the critical conditions of energy band reversal, and developing the topological insulation state. Finally, we study the transport properties of 2D-2D and 1D-1D GaSb/Si/InAs heterostructure device using the non-equilibrium Green's function electron transport theory. Our results may confirm that GaSb/Si/InAs heterostructure most likely overcome the leakage current, high sub-threshold swing, and bipolar effect. Our investigation is important for the development of low sub-threshold swing, high rectification ratio, and low energy consumption device.

具有高迁移率III-V族GaSb/InAs异质结器件能够实现超快传导速度和高隧穿几率，然而高亚阈值摆幅和双极效应问题，成为制约其发展的关键因素。本项目提出GaSb/Si/InAs双异质结纳米器件设计，试图通过结构改性、能带调控和新颖量子态等提高器件性能。首先，基于第一性原理计算方法，建立随Si嵌入厚度和界面应力变化的能带结构，寻找具有II类能带结构和极低隧穿势垒的结构。其次，揭示极性界面形成的内电场与应力对能带结构的协同作用，探究能带反转的临界条件，发掘无热损耗的拓扑绝缘态。最后，采用非平衡格林函数电子输运理论，研究2D-2D和1D-1D GaSb/Si/InAs 异质结纳米器件的输运性质，利用新颖的物理结构性质，克服GaSb/InAs器件漏电流、高亚阈值摆幅和双极导通等应用缺陷，实现性能改善。项目对开发低亚阈值摆幅、高整流比、低损耗的GaSb/Si/InAs TFET器件具有重要意义。

以GaSb和InAs为结构单元的异质结以其独特的结构特征和电学特性成为当前信息科学和纳米材料领域的研宄热点。.我们通过计算模拟与理论分析，系统研究了基于GaSb和InAs的纳米结构的电子结构和输运性质，获得了一些具有意义的结果，主要有：(1)研究了[111]方向的GaSb/Si/InAs薄膜异质结界面对电子结构的影响。研究结果表明，在Si量子井结构的上下界面形成极性键，形成积累电子和空穴积累，产生内建极化电场。量子限域效应和界面极化电场的竞争，共同决定了Si量子阱的带隙。随着Si层数的增加，量子局域效应减小，极化电场显著降低系统能隙直至关闭能隙，甚至能带反转；(2)应变对p-n 型GaSb/InAs核壳纳米线电子结构和载流子迁移率作用效果明显。增加壳层InAs-shell厚度，降低体系的能隙，增强载流子的非局域性，明显提升迁移率。单轴拉伸应力起到降低核壳纳米线带隙、减小有效质量、显著提高载流子迁移率的作用；(3)计算发现作为III-V族高迁移率半导体InAs，其二维单层InAs的迁移率高达1100cm2/V•s。亚10nm以下二维InAs TFET器件的开态电流均满足国际半导体路线图的参数要求，亚阈值摆幅SS低至58mV/dec；(4)研究了InAs/Graphene异质结构的电子结构和输运性质发现，通过构建界面杂化和InAs/Graphene异质结构器件中的接触势垒，实现电子-空穴对在不同界面的分布，以实现整流和负微分电阻行为。InAs/Graphene异质结构的界面静电势分布和接触势垒在决定输运特性中起重要作用；(5)研究了表面悬挂键(SDBs)对Mn掺杂GaAs纳米线磁性的影响。结果表明，Mn-3d轨道与残余SDB之间发生电荷转移，有效地调节总磁矩，提高居里温度。项目研究结果对发展高性能、低功耗的GaSb和InAs异质结纳米器件具有重要意义。