Phase-controlled synthesis of SnS₂and SnS flakes and photodetection properties

Two-dimensional (2D) layered tin sulfide compounds including SnS₂and SnS have attracted increasing attention due to their great potential application in the fields of optoelectronics and energy storage. However, device development has been delayed by the lack of capabilities to synthesize large-scale and high-quality 2D tin sulfide. Here, a phase-controlled synthesis of SnS₂and SnS flakes with lateral size over 100 μm was successfully realized via a facile chemical vapor deposition method. The lateral size of flakes and phase transformation of SnS₂to SnS can be tuned via changing the synthesis temperature. Compared to the formation of the SnS₂phase at relative low temperature (<750 °C), the SnS phase is favorable at higher temperature. The phototransistor based on the as-prepared SnS₂and SnS exhibits excellent photoresponse to 405 nm laser, including a high responsivity (1.7 × 10⁶mA W^-1), fast response rates (rise/decay time of 13/51 ms), an outstanding external quantum efficiency (5.3 × 10⁵%), and a remarkable detectivity (6.24 × 10¹²Jones) for SnS₂-based phototransistor, and these values are superior to the most reported SnS₂based photodetectors. Although the responsivity (3390 mA W^-1) and detectivity (1.1 × 10¹⁰Jones) of SnS-based device is lower than that of the SnS₂phototransistor, it has a faster rise/decay time of 3.10/1.59 ms. This work provides a means of tuning the size and phase of 2D layered tin sulfide, and promotes the application of SnS₂in high-performance optoelectronic devices.