High-performance multilayer WSe2/SnS2 p-n heterojunction photodetectors by two step confined space chemical vapor deposition.

Two-dimensional (2D) p-n heterojunctions have attracted great attention due to their outstanding properties in electronic and optoelectronic devices, especially in photodetectors. Various types of heterojunctions have been constituted by mechanical exfoliation and stacking. However, achieving controlled growth of heterojunction structures remains a tremendous challenge. Here, we employed a two-step KI-assisted confined-space chemical vapor deposition (CVD) method to prepare multilayer WSe2/SnS2 p-n heterojunctions. Optical characterization results revealed that the prepared WSe2/SnS2 vertical heterostructures have clear interfaces as well as vertical heterostructures. The electrical and optoelectronic properties were investigated by constructing the corresponding heterojunction devices, which exhibited good rectification characteristics and obtained a high detectivity of 7.85 × 10^12 Jones and a photoresponse of 227.3 A/W under visible light irradiation, as well as a fast rise/fall time of 166/440 μs. These remarkable performances are likely attributed to the ultra-low dark current generated in the depletion region at the junction and the high direct tunneling current during illumination. This work demonstrates the value of multilayer WSe2/SnS2 heterojunctions for applications in high-performance photodetectors.&#xD.