Due to its exceptional photovoltaic properties and freedom from crystal lattice matching constraints, transition-metal dichalcogenides (TMDCs) have gained increased attention as a prospective two-dimensional (2D) layered material. Van der Waals heterojunctions (vdWHs) constituted of these materials afford chances for the advancement of high-performance photodetectors and solar cells. However, low light absorption efficiency and electron/hole traps at heterointerfaces make it difficult to improve the response speed and sensitivity of TMDCs vdWH based photodetectors. Here, we designed and realized a GFET-coupled MoS/WSe heterojunction gain photodetector. An interfacial amplification effect is induced when a graphene field-effect transistor (GFET) is coupled to a MoS/WSe heterojunction because of the lengthy carrier lifetime of MoS and the ultrahigh mobility of graphene. This effect leads to a high gain for our device, enhancing the photovoltaic response. Compared to the pristine MoS/WSe heterojunction, the device exhibits two to three orders of magnitude improvement in responsivity, up to 50 A/W. Rising and decaying times of 67 μs and 2 μs are also achieved, respectively. By utilizing the strong correlation between the incident light spot position and the photocurrent, the device also enables sensitive detection of the spot position. This research offers an attainable method for developing gain-type, high-speed photodetectors.

中文翻译：

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具有 GFET 耦合 MoS2/WSe2 异质结的增益型光电探测器


由于其卓越的光伏特性和不受晶格匹配限制，过渡金属二硫属化物（TMDC）作为一种有前景的二维（2D）层状材料受到越来越多的关注。由这些材料构成的范德华异质结（vdWH）为高性能光电探测器和太阳能电池的发展提供了机会。然而，低光吸收效率和异质界面处的电子/空穴陷阱使得基于TMDC vdWH的光电探测器的响应速度和灵敏度难以提高。在这里，我们设计并实现了 GFET 耦合 MoS/WSe 异质结增益光电探测器。由于MoS的长载流子寿命和石墨烯的超高迁移率，当石墨烯场效应晶体管（GFET）耦合到MoS/WSe异质结时会产生界面放大效应。这种效应为我们的设备带来了高增益，增强了光伏响应。与原始的 MoS2/WSe 异质结相比，该器件的响应度提高了两到三个数量级，高达 50A/W。上升时间和衰减时间也分别为 67 μs 和 2 μs。通过利用入射光斑位置与光电流之间的强相关性，该装置还能够灵敏地检测光斑位置。这项研究为开发增益型高速光电探测器提供了一种可行的方法。