Effects of atomic defects at lateral and vertical metal-semiconductor interfaces on the properties of the two-dimensional transition metal dichalcogenide heterostructures

如果不能完全了解金属和半导体异质结界面处发生的物理现象，基于过渡金属二卤代化合物(TMD)的二维异质结在未来的电子和光学器件中的应用是不可能的。我们将研究由相邻两种材料生长而成的横向异质结构中的选定的2D TMD金属-半导体界面，以及在单层半导体TMD上放置单层金属TMD的垂直结构中。由于实际器件中经常会出现杂质、掺杂和空位等缺陷，本课题的目的是研究这些缺陷对横向和垂直异质界面的结构和电子性质的影响。我们使用合作伙伴提供的CVD生长的横向TMD异质结构，并通过夹层和冲压技术制备垂直TMD异质结构。用具有球差和色差校正的低电压高分辨率电子显微镜研究界面的原子结构，用电子能量损失谱研究等离子体激子、激子和核态。实验结果将通过第一性原理计算得到合理的结果，从中我们期望对界面缺陷对2D异质结构性质的作用有更深入的了解。

The applications of two-dimensional (2D) heterostructures based on transition metal dichalcogeni-des (TMDs) in future electronic and optical devices is hardly possible without a complete under-standing of the physical phenomena occurring at the interfaces in metallic and semiconducting heterostructures. We will study selected 2D TMD metallic-semiconducting interfaces in lateral het-erostructures produced by growth of two materials next to each other, and in the vertical configu-ration with a single-layer metallic TMD placed on top of a single-layer semiconducting TMD. As at-omistic defects such as contaminations, dopants, and vacancies will be always present in practical devices, the aim of this project is to study the influence of these defects on the structure and on the electronic properties of the lateral and vertical heterointerfaces. We use CVD–grown lateral TMD-heterostructures as provided by cooperation partners and we prepare the vertical TMD hetero-structures by sandwiching and stamping techniques. The atomic structure of the interfaces will be investigated by low-voltage high-resolution TEM with spherical and chromatic aberration correc-tion, and the plasmon, excitons and core states will be studied by electron energy-loss spectrosco-py. The experimental findings will be rationalized through first-principles calculations from which we expect to gain in-depth understanding of the role of interfacial defects on the properties of the 2D heterostructures.