Salt-promoted growth of monolayer tungsten disulfide on hexagonal boron nitride using all chemical vapor deposition approach

Monolayer tungsten disulfide (WS2), an emerging two-dimensional (2D) direct-bandgap semiconductor, provides new prospects for next-generation electronic, optoelectronic and valleytronic devices. However, the physical properties of 2D WS2, are seriously perturbed by various extrinsic disorders to a large extent. Despite encap-sulating exfoliated WS2 with hexagonal boron nitride (h-BN) flakes can effectively screen the surrounding dis-orders, its scalability is not applicable to large-area electronics. In this work, the construction of monolayer WS2 on h-BN is achieved with an all chemical vapor deposition (CVD) approach by using alkali metal salt to promote the growth of WS2. Detailed characterizations indicate that WS2 deposited on h-BN exhibits improved optical and electrical properties, as compared to those on SiO2/Si substrates. Furthermore, the influence of depositing WS2 on h-BN and salt-promoted growth behavior of WS2 is systematically investigated, highlighting the important role of salt in constructing the heterobilayers. This work paves a practical way for synthesis of 2D materials on h-BN to further probe their intrinsic properties and enable a plethora of potential applications.

Automated summary

This study successfully constructs monolayer tungsten disulfide on hexagonal boron nitride using chemical vapor deposition, and demonstrates improved optical and electrical properties compared to those on silicon substrates. Additionally, the study highlights the important role of salt in building the heterobilayer structure.