Phase-controlled synthesis of SnSand SnS flakes and photodetection properties.

Two-dimensional (2D) layered tin sulfide compounds including SnSand 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 SnSand SnS flakes with lateral size over 100 m was successfully realized via a facile chemical vapor deposition method. The lateral size of flakes and phase transformation of SnSto SnS can be tuned via changing the synthesis temperature. Compared to the formation of the SnSphase at relative low temperature (<750 °C), the SnS phase is favorable at higher temperature. The phototransistor based on the as-prepared SnSand SnS exhibits excellent photoresponse to 405 nm laser, including a high responsivity (1.7 × 10mA W), fast response rates (rise/decay time of 13/51 ms), an outstanding external quantum efficiency (5.3 × 10%), and a remarkable detectivity (6.24 × 10Jones) for SnS-based phototransistor, and these values are superior to the most reported SnSbased photodetectors. Although the responsivity (3390 mA W) and detectivity (1.1 × 10Jones) of SnS-based device is lower than that of the SnSphototransistor, 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 SnSin high-performance optoelectronic devices.