Controllable synthesis of SnS2 flakes and MoS2/SnS2 heterostructures by confined-space chemical vapor deposition

Abstract

Two-dimensional (2D) group-IV metal dichalcogenides (GIVMDs) like chalcogenide tin disulfide (SnS₂) 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 SnS₂ 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 SnS₂ flakes, which are parallel to the substrate and have the characteristics of better crystallinity and fewer S vacancies. The SnS₂ FET devices exhibit a mobility of 0.39 cm² V⁻¹ s⁻¹ and an on/off ratio of 10⁴. The corresponding SnS₂ 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 MoS₂/SnS₂ 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.