High on/off ratio photosensitive field effect transistors based on few layer SnS₂

2D layered SnS₂ nanosheets have attracted increasing research interest due to their highly anisotropic structural, electrical, optical, and mechanical properties. Here, through mechanical exfoliation, few-layer SnS₂ was obtained from as-synthesized many-layered bulk SnS₂. Micro-characterization and Raman study demonstrate the hexagonal symmetry structure of the nanosheets so fabricated. The energy band structures of both SnS₂ bulk and monolayer were investigated comparatively. A highly photosensitive field effect transistor based on the obtained few-layer SnS₂ nanosheets was fabricated, which shows a high I _photo/ I _dark ratio of 10³, and keeps the responsivity and external quantum efficiency ( EQE ) at a realistic level of 8.5 A W⁻¹ and 1.2 × 10³% respectively. This 2D structured high on/off ratio photosensitive field effect device may find promising potential applications in functional electronic/optoelectronic devices or systems. (letter)