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 10(3), and keeps the responsivity and external quantum efficiency (EQE) at a realistic level of 8.5 A W(-1) and 1.2 × 10(3)% respectively. This 2D structured high on/off ratio photosensitive field effect device may find promising potential applications in functional electronic/optoelectronic devices or systems.