二维拓扑晶态绝缘体可控生长及表面态输运调控

Topological crystalline insulators (TCIs) are recently discovered topological phase with gapless metallic surface states residing on highly-symmetry crystal surfaces. Interestingly, their electronic properties of surface states can be effectively modulated by temperature, thickness, composition, electric field and strain, indicating promising applications of TCIs in low-dissipation logic devices, tunable electronic devices and pressure sensors. However, the fundamental physics of topological surface electrical transport of TCIs are not very well documented. And, up to now, no work reports the study of electric field- or strain-controlled surface states transport, which is crucial for developing practical high-speed topological transistor. Compared with their bulk counterparts, TCIs nanostructures can more effectively enhance the contribution of surface states electrical transport due to their large surface-to-volume ratios. Especially two-dimensional (2D) nanostructures are more advantaged in strengthening the surface states transport since they have dominant top and bottom surfaces. In this study, we are going to explore the controllable growth of 2D TCIs nanostructures and understand the thermal dynamics of 2D anisotropic growth. Further, we will study the transport modulation of topological surface states by exerting external physical disturbing and find the physical principle of surface transport modulation. This work is significantly important for understanding the basic physics of TCIs and will promote their practical applications in low-dissipation functional devices.

拓扑晶态绝缘体是一种受晶格对称性保护的新型拓扑绝缘体，它不仅具有超高的表面电子迁移率，而且它的带隙和表面态可通过温度、组分、厚度、电场和应力等物理化学参量调控，因而在低能耗逻辑器件，可调谐电子器件和应压力传感器件等领域具有巨大的应用潜力。然而拓扑晶态绝缘体表面态输运调控基本物理问题研究尚处于起步阶段，尤其是电场或应力对表面态输运调控的实验研究尚处于空白。拓扑绝缘体纳米化是一种增强表面态输运的有效途径，这其中二维纳米结构具有占统治优势的上下表面，能显著增强表面态对电输运的贡献，是探索表面输运的理想结构。本项目致力于探索拓扑晶态绝缘体二维各向异性生长的热动力学问题，研究二维拓扑晶态绝缘体表面态调控的基本物理原理。该工作将加强研究者对低维拓扑晶态绝缘体表面态相关的基础问题的理解，推进拓扑晶态绝缘体在低能耗功能器件领域的应用。

拓扑晶态绝缘体在低功耗电子器件领域具有重要的应用前景，本项目围绕新型二维拓扑晶态绝缘体的合成制备、物性调控和器件应用等方面展开研究，取得的主要成果有：.（1）针对传统的异质外延生长过程中面临异质界面的多物理失配问题，发展了具有较普适性的范德华外延生长技术，已实现了多种新型二维电子材料的范德华外延制备。该方法能够有效突破传统外延晶格匹配限制，抑制位错或缺陷在外延过程中的传递，从而实现了高质量的异质外延。.（2）二维电子材料具有原子级的超薄厚度，因此空位、缺陷、表界面态对材料性能具有重大影响。本项目通过构筑基于新型二维半导体材料的光电器件，深入开展了二维电子材料表界面态的细致研究，揭示了TMDC材料中空位、缺陷等对电学和光电性能的调控机制。最终优化材料合成及器件结构获得了高性能光电探测器及光电晶体管。.（3）利用二维材料可任意堆垛的特点，开展了异质集成研究，实现了材料特性的优势互补，结合缺陷工程、能带工程、界面工程等机制/手段精准调控异质结构性能，构筑了超快、超宽光谱响应的高性能二维半导体光电器件。.经过4年的研究发表相关研究成果47篇，其中影响因子大于10的论文35篇，包括Nature Electronics 1篇，Nature Communications 1篇，Science Advances 1篇，Chemical Society Reviews 1篇，Advanced Materials 9篇，Nano Letters和ACS Nano 4篇， Advanced Functional Materials 10篇，Advanced Energy Materials 1篇， Advanced Sciences 1篇。申请中国专利12项，其中已授权4项。较好完成项目目标。