Controllable synthesis of SnS flakes and MoS/SnS heterostructures by confined-space chemical vapor deposition

Two-dimensional (2D) group-IV metal dichalcogenides (GIVMDs) like chalcogenide tin disulfide (SnS 2 ) have received widespread attention due to their diverse crystal structures, strong light absorption capacity and excellent photoelectric properties. However, the CVD growth of GIVMDs like SnS 2 remains challenging because GIVMDs tend to grow in out-of-plane directions. Here, we develop a halogen salt-assisted confined-space CVD method for the controllable synthesis of SnS 2 flakes, which are parallel to the substrate and have the characteristics of better crystallinity and fewer S vacancies. The SnS 2 FET devices exhibit a mobility of 0.39 cm 2 V −1 s −1 and an on/off ratio of 10 4 . The corresponding SnS 2 photodetectors show a responsivity of 16 mA W −1 and a response time of 20 ms. We further utilize such a halogen salt-assisted confined-space CVD method to prepare vertical double-layer MoS 2 /SnS 2 heterostructures with good uniformity and high quality by a one-step process. The salt-assisted and confined space CVD approach provides a reliable method for the controllable synthesis of 2D GIVMDs as well as their vertical heterostructures. A halogen salt-assisted confined-space CVD method is used for the controllable synthesis of SnS 2 flakes, which are parallel to the substrate and have the characteristics of better crystallinity and fewer S vacancies.