A type of broadband (325−980 nm) self-powered photodetector based on graphene/GaAs van der Waals heterojunction is reported. By simply spinning a layer of Ag nano-particles (Ag NPs) onto graphene/GaAs heterostructure, the responsivity and detectivity of our devices for the whole spectrum range are enhanced significantly. The maximum photocurrent responsivity of 210 mA W⁻¹ (increased by 38%) and detectivity of 2.98 × 10¹³ Jones (increased by 202%) are achieved at 405 nm, which is about two or three orders of magnitude larger than other graphene based self-powered photodetectors. The mechanism of the improvement originates from the overlap the depletion region of graphene/GaAs heterostructure, the surface plasmon enhanced light field region below the surface and the light absorption region of the GaAs layer. The external quantum efficiency (EQE) measurement, transient photoluminescence (PL) test and the comparative theoretical simulation show that the surface plasmon enhancement should only be applicable for graphene/direct band gap semiconductor heterostructure, where the semiconductor should have a high optical absorption coefficient. The obtained high performance broadband photodetector with excellent detectivity is a promising candidate for many important optoelectronic applications, such as ultrasensitive image sensor in charge coupled displayer field, which requires colour sensors not only with high photo responsivity but also in a wide spectral range.

报告了一种基于石墨烯/ GaAs van der Waals异质结的宽带（325-980 nm）自供电光电探测器。通过简单地将一层Ag纳米粒子（Ag NPs）旋转到石墨烯/ GaAs异质结构上，我们的设备在整个光谱范围内的响应度和检测率都得到了显着提高。最大光电流响应率为210 mA W ^-1（增加了38％），探测率为2.98×10 ¹³在405 nm处实现Jones（增加202％），比其他基于石墨烯的自供电光电探测器大2到3个数量级。改善的机理源自重叠的石墨烯/ GaAs异质结构的耗尽区，表面下方的表面等离子体激元增强的光场区和GaAs层的光吸收区。外部量子效率（EQE）测量，瞬态光致发光（PL）测试和比较理论仿真表明，表面等离子体激元增强仅应适用于石墨烯/直接带隙半导体异质结构，其中半导体应具有较高的光吸收系数。