Theoretical and experimental study of optical properties of 2D material heterostructures

随着光基技术在现代世界中变得不可或缺，对高性能新型光学材料的需求不断增长，光学器件在能效和成本效益方面的优化备受关注。低维材料具有独特的优势，有望实现下一代创新技术。特别是，垂直堆叠2D材料的机会为异质结构和带隙工程提供了巨大的可能性。在这里，一个联合的理论和实验研究（尚未开发）MoSe 2/MoTe 2和WSe 2/MoTe 2单层（ML）异质结（HS）的光学性质将进行。通过这种方式，将通过研究MoSe 2/MoTe 2的II型HS是否/如何保留其相应ML的直接带隙来证明对该材料类别及其可能应用的理解，并且由于夹层的存在而成为光伏器件和探测器的有希望的候选者- 由于层内激子的存在，WSe 2/MoTe 2的I型HS是应用于低阈值二极管激光器的理想结构- 异质结使ML的光学性质恶化;-晶格失配和衬底显著影响HS的光学性质。

As light-based technologies have become indispensable in our modern world, demand for high-performing novel optical materials is growing and optimization of optical devices with respect to energy efficiency and cost effectiveness receives much attention. Low-dimensional materials feature unique advantages over their bulk counterparts and are expected to enable next-generation innovative technologies. Particularly, the opportunity of vertically stacking 2D materials offers vast possibilities of heterostructuring and band-gap engineering. Here, a joint theoretical and experimental study of optical properties of the (yet unexplored) MoSe2/MoTe2 and WSe2/MoTe2 monolayer (ML) heterostructures (HS) will be conducted. In this way the understanding of this material class and their possible applications will be demonstrated by investigating whether/how- Type-II HS of MoSe2/MoTe2 retains the direct band gap of their corresponding MLs and is a promising candidate for photovoltaic devices and detectors due to the presence of interlayer (or indirect) excitons;- Type-I HS of WSe2/MoTe2 is an ideal structure to be applied in low-threshold diode lasers due to the presence of intralayer (or direct) excitons;- Heterostructuring deteriorates the optical properties of MLs;- Lattice mismatch and substrate significantly affect the optical properties of HS.