中文摘要：

二维（2D）材料由于独特的结构和新颖的物理化学性质,近几年受到越来越多的关注.作为2D家族最耀眼的成员,2D半导体有可能实现多功能电子和光电子器件化.本文综述了近几年2D半导体光电探测器的研究进展,讨论和介绍了光电流产生的几种机制以及评价光电探测器性能的重要参数;总结了最近几年发展的各种2D半导体光电探测器,其中包括单一2D半导体和它们的混合维度结构,以及几种改善光电性能的策略.最后,对全文做了简单回顾并展望了该领域的未来发展方向.

英文摘要：

Two-dimensional（2D） materials have attracted increasingly great interest in recent years due to their unique structures and novel physical and chemical properties. 2D semiconductors, the brightest member of the family of 2D materials, allow for realizing versatile electronic and optoelectronic devices. Their layered structure and atomic thickness render them have promising applications in monolithic integration, flexible devices and wearables electronics. Moreover, their bandgaps are usually related to the thickness and external strain, which mean the electronic optoelectronic properties can be tuned by changing the number of layers or strain engineering. Interestingly, some 2D semiconductors such as black phosphorus, GeS, and Re S2 have low symmetry crystal structures, their electronic and optical properties are highly anisotropic, such characteristics give us another degree of freedom to photodetections using polarized light. This feature article reviews the recent research activities that focus on applications of 2D semiconductors as photodetectors. It begins with survey of photocurrent generation mechanisms, which include photoconductive effect, photogating effect, photovoltaic effect, photo-thermoelectric effect and bolometric effect. These mechanisms are systematically introduced and discussed. Then, the general meaning of figure of merit that evaluates the performance of photodetectors is introduced, including responsivity, external quantum efficiency, time response, signal to noise ratio, noise equivalent power, detectivity. Furthermore, the recent photodetectors based on 2D semiconductors including transition metal dichalcogenides（TMDs）, black phosphorus, ternary chalcogenides and their hybrid structures such as 2D-0D, 2D-1D, 2D-2D and 2D-3D structures are presented. Mo S2 is the most studied TMD semiconductor, photodetectors based on monolayer and multilayers Mo S2 are widely studied, some strategies including doping, encapsulation, and device design for improving photoelectronic performance are