Multilayer SnS2/few-layer MoS2 heterojunctions with in-situ floating photogate toward high-performance photodetectors and optical imaging application

Since the successful preparation of the monolayer MoS2 phototransistor, two-dimensional (2D) layered materials (2DLMs) have been regarded as one of the most compelling candidates toward the implementation of the next generation of novel optoelectronic devices and systems. However, most reported 2DLM photodetectors suffer from specific shortcomings, such as low responsivity, large dark current, low specific detectivity, low on/off ratio, and sluggish response rate. Herein, multilayer SnS2/few-layer MoS2 van der Waals heterostructures have been constructed by stacking the MoS2 and SnS2 nanosheets grown by a single atmospheric pressure chemical vapor deposition method. The SnS2/MoS2 heterojunction photodetector demonstrates competitive overall performance with a large on/off ratio of 171, a high responsivity of 28.3 A W−1, and an excellent detectivity of 1.2 × 1013 Jones. In addition, an ultrafast response rate with the response/recovery time down to 1.38 ms/600 is achieved. The excellent properties are associated with the synergy of type-II band alignment of SnS2/MoS2 and the in-situ formed seamless floating photogate, which contribute to separating the photoexcited electron-hole pairs and extending the carrier lifetime. Taking advantage of the excellent photosensitivity, the SnS2/MoS2 device demonstrates proof-of-concept optical imaging application. On the whole, this study provides a distinctive perspective to implement advanced photodetectors with competitive overall performance.