十多年来，通过对以石墨烯为代表的二维材料的可控生长、物性表征、器件开发的研究使这一领域的前景更为广阔。过渡金属二硫族化合物(TMDC)是二维材料中另一类重要的功能材料，在光电子学、柔性电子学等领域有实用价值。而由不同TMDC薄膜构成的纵向范德华异质结对进一步拓展光电器件性能、开创新型器件具有关键意义。本项目拟以二硫化钼(MoS2)和二硒化钨(WSe2)两种重要的TMDC为例，采用金属有机化学气相沉积(MOCVD)技术生长晶圆尺寸、低成核密度、高结晶质量的单层薄膜，并在此基础上通过范德华外延机制原位直接生长MoS2/WSe2范德华异质结。我们将探索合适的生长衬底、气态源、生长参数等控制异质结成核和生长动力学过程，优化生长条件，预期在2英寸衬底上获得均匀双层面积超过95%的高结晶质量、原子级陡峭界面的范德华异质结薄膜。我们还将系统研究异质结的光电性能并构筑二维光伏、光探测器及其大面积器件阵列。

During the last decade, two-dimensional (2D) materials, e.g. graphene, have attracted extensive research interests in controlled growth, characterizations of physical properties, and design/construction of functional devices. Transition metal dichalcogenide (TMDC) is another type of functional 2D material, promising in optoelectronics, flexible electronics, and so on. More importantly, one can stack different TMDC layers into van der Waals heterostructures that are capable to improve the existing electronic and optical properties, but also create new functionality for applications. In this proposal, taking molybdenum disulfide (MoS2) and tungsten diselenide (WSe2) as examples, we would like to use metal-organic chemical vapor deposition (MOCVD) to grow wafer-scale, low nucleation density, single-layer films, and then in-situ grow wafer-scale MoS2/WSe2 van der Waals heterostructures via the van der Waals epitaxy mechanism. We will intensively explore various experimental details, such as proper substrates, gas-phase precursors, and processing parameters, to achieve the optimal growth conditions for 2 inch size uniformity, high crystalline quality heterostructures with atomically abrupt interface. We will then fabricate TMDC heterostructure-based photovoltaic and photo-detecting devices and device arrays for outstanding performance.