界面调控常规半导体拓扑绝缘体相变

Topological insulators have aroused enormous interests for its unique electronic structures. However, the application of topological insulators in future spintronics is currently restricted by the small spin-orbital coupling induced bandgap and the rare abundance of the elements. An alternative way is to drive commonly-used semiconductors into topological insulator phases. In this application, we construct direct bandgaped semiconductor heterostructures and superlattices by rational design. Accompanied with interface strain manipulation, the strong intrinsic polarized electric field induced by the charge accumulation in each interface will invert the bandgap, generate large Rashba spin-orbit coupling effect and finally drive commonly-used semiconductors into topological insulators. In order to accurately describe this topological phase transition, we will develop a fast and efficient electronic structures calculation code based on the state-of-arts first-principles calculations.

近年来拓扑绝缘体引起了凝聚态物理学领域浓厚的研究兴趣。拓扑绝缘体在下一代自旋电子学器件的应用可能受到两大因素的制约：一则因为自旋轨道耦合打开的反转带隙较小，易受热扰动湮没，二则因为组成拓扑绝缘体的元素一般丰度较低，可能难于广泛应用。本项目旨在通过合理的界面设计把常规半导体驱动到拓扑绝缘体相。关键在于利用半导体异质结与超晶格极性界面处的电荷积累，同时辅以界面应力调制等手段，以获得极强的内建电场。 这一内建电场可以反转常规半导体能带顺序，并显著增强Rashba自旋轨道耦合强度，从而实现传统常规半导体的拓扑绝缘体转变。

项目执行紧扣研究总体目标，通过对传统半导体界面、二维材料平面内异质结界面、二维材料范德瓦尔斯界面以及混合维度界面的广泛研究，证明了界面作为一个普适手段，可以有效调控系统电子结构，实现丰富物相。我们按照计划完成了一套快速、精确的界面系统计算方法。超越最初4-6篇发表文章的指标，三年间发表SCI收录论文23篇，其中包括PRL 1篇，PRB重点推荐文章2篇，2D Materials 2篇，ACS NANO 3篇，JPCL 1篇，Materials Today 1篇，上述论文发表至今已被引用300余次，其中不乏国际同行的高度评价。项目执行期满，共培养博士毕业生两名，完成了人才培养指标。