High-performance ultra-violet phototransistors based on CVT-grown high quality SnS2 flakes

van der Waals layered two-dimensional (2D) metal dichalcogenides, such as SnS2, have garnered great interest owing to their new physics in the ultrathin limit, and become potential candidates for the next-generation electronics and/or optoelectronics fields. Herein, we report high-performance UV photodetectors established on high quality SnS2 flakes and address the relatively lower photodetection capability of the thinner flakes via a compatible gate-controlling strategy. SnS2 flakes with different thicknesses were mechanically exfoliated from CVT-grown high-quality 2H-SnS2 single crystals. The photodetectors fabricated using SnS2 flakes reveal a desired response performance (R-lambda approximate to 112 A W-1, EQE approximate to 3.7 x 10(4)%, and D* approximate to 1.18 x 10(11) Jones) under UV light with a very low power density (0.2 mW cm(-2) @ 365 nm). Specifically, SnS2 flakes present a positive thickness-dependent photodetection behavior caused by the enhanced light absorption capacity of thicker samples. Fortunately, the responsivity of thin SnS2 flakes (e.g. similar to 15 nm) could be indeed enhanced to similar to 140 A W-1 under a gate bias of +20 V, reaching the performance level of thicker samples without gate bias (e.g. similar to 144 A W-1 for a similar to 60 nm flake). Our results offer an efficient way to choose 2D crystals with controllable thicknesses as optimal candidates for desirable optoelectronic devices.