Broadband and high-performance SnS2/FePS3/graphene van der Waals heterojunction photodetector

Two-dimensional materials and their heterojunctions have received extensive attention in fundamental and applied research of photonics, electronics, and spintronics. Herein, we stacked SnS2, FePS3, and graphene (Gr) nanosheets into SnS2/FePS3/Gr van der Waals heterojunction, which exhibits broadband photoresponse from an ultraviolet region (405 nm) to an infrared region (850 nm) in atmosphere at room temperature. It was found that the dominated carrier of SnS2/FePS3 and SnS2/FePS3/Gr hererojunction was different in the electrical transport. The photoresponsivity of SnS2/FePS3/Gr heterojunction was about two orders of magnitude higher than that of SnS2 and FePS3 and SnS2/FePS3 heterojunction. The response time of SnS2/FePS3/Gr heterojunction was slightly shorter than that of SnS2/FePS3 heterojunction and two orders of magnitude shorter than that of SnS2 and FePS3 under the 450 nm laser. The high responsivity and short response time of SnS2/FePS3/Gr heterojunction should be attributed to the type II band alignment and short channel distance in the vertical direction where electrons and holes can be separated and transit fast. Our result offered an opportunity for realization of the high-performance and broadband photodetector.