MoS2/p-Si heterojunction with graphene interfacial layer for high performance 940 nm infrared photodetector

In this work, we report on an experimental demonstration of a molybdenum disulfide (MoS2)/p-Si heterojunction with a graphene (Gr) interfacial layer for a high-performance infrared (IR) photodetector. The photoresponsivity and detectivity of the fabricated MoS2/Gr/p-Si photodiode device were significantly improved (responsivity: 1.01 A/W and detectivity: 7.9 × 1010 Jones which were obtained at −2 V), which is 2–3 times higher than the corresponding values of a control photodiode with a MoS2/p-Si structure. The proposed photoresponsive model highlights that a Gr layer with its unique zero band gap does not only contribute to electron-hole pair generation enough for it to be detected even under relatively low IR light, but also, that its atomically smooth van der Waals interface suppresses trap-based recombination and facilitates the charge separation to each electrode region, all of which are experimentally and theoretically supported by a strong power-law relationship and energy band diagrams. In photoresponsive dynamics, fast and reliable photoswitching behaviors were observed during the iterative on/off light pulse cycling test, resulting in no serious current fluctuations. These mixed-dimensional 2D/2D/3D hybrid heterojunction structures pave the way for high-performance IR-detection applications.