二维过渡金属硫化物/钙钛矿异质结构的光电性能研究

As emerging two-dimensional (2D) semiconductors, transitional mental dichalcogenides (TMDs) have attracted increasing research interests. The representative TMDs, such as MoS2, WS2, and WSe2 etc. present interesting photoelectrical properties because of their band gaps could be tuned via changing thickness, and they have been demonstrated as potential building blocks for next generation advanced optoelectronics of high-speed photodetectors. However, the practical applications of TMDs in high performance photodetector are restricted due to their features of lower absorption of light, high exciton binding energy resulting strong force between electron-hole pairs, and so forth. This project will focus on the experiments of design and fabrication of optoelectronic devices based on ultra-thin 2D materials and investigation of the involved physics fundamentals. The approaches of decoration of the surface of TMDs using perovskite thin films or quantum dots will be employed to improve the absorption of light. Design and fabrication of TMDs/perovskite heterojunctions with type-II or p-n junction structures will be utilized to promote the separation of electron-hole pairs, as a result of increasing the photocurrent. Employing the band gap engineering enabled by tuning the thickness of TMDs and composition of perovskites will extend the spectral response range. The aim is to obtain continues response covering the range from UV to NIR. At the end, by a series of optimization of the device architecture, the goal of the project is to fabricate high performance photodetectors with high responsivity and wide spectral response range.

作为新型二维半导体材料，过渡金属硫族化合物（TMDs）已经成为当前的研究热点。由于其带隙随层数可调，多种典型TMDs，例如MoS2，WS2，WSe2等，表现出优异的光电性能，被证实可用于研制下一代高速光探测器等先进光电器件。但由于单层TMDs吸光率低、激子束缚能大导致电子-空穴不易分离等特点，阻碍了其在高性能光探测方面的应用。本项目将围绕超薄二维材料光电器件的设计、制备以及物理性质研究开展工作。通过用钙钛矿薄层或量子点修饰TMDs表面，提高光吸收率；设计并构建type-II型或p-n结型TMDs/钙钛矿异质结构，促进电子-空穴对的分离，增大光电流；利用TMDs中层数对带隙的调制以及钙钛矿材料成份对其带隙的调制，拓宽光谱响应范围，达到从紫外到近红外的连续响应；最终，通过优化结构，制备出宽光谱、高响应的高性能光电探测器。

项目执行期间，针对二维材料/新型钙钛矿材料异质结构的光学和光电性能研究，我们主要开展了以下工作：（1）二维材料、新型钙钛矿材料及其异质结构的按需构筑。开发了“硫控”生长技术，实现了过渡金属硫化物的精准制备；利用多技术结合，实现了新型钙钛矿低维结构（0D、1D、2D）的制备；利用堆垛转移技术，实现了2-5层异质结构的制备。（2）二维材料、新型钙钛矿材料及其异质结构的光学、光电性能研究。利用多种光谱学技术对发光性能、瞬态光电导等进行精确表征，解析了材料载流子动力学以及异质结间载流子转移机制。（3）基于制备的材料和异质结构，构建二维光电探测器。利用精确表征建立的理论模型对器件性能进行优化，实现了高灵敏、快速响应、宽光谱的光电探测器。项目资助下，共发表论文15篇，其中以第一作者或者通讯作者身份发表论文12篇。培养博士生研究生6人，硕士研究生13人。