Chemical vapor deposition of high-quality monolayer transition metal disulfides

Two-dimensional semiconductors, transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) are an emerging material family with rich physical and chemical properties. Specifically, atomically thin monolayer TMDs exhibit direct bandgaps, strong photoluminescence, significant spin-valley coupling, and active edge sites, making them a promising candidate for applications in next-generation ultra-scaled electronics, flexible optoelectronics, spintronic devices, and nanobiosensors. To date, many methods have been developed to obtain monolayer TMDs, including mechanical and chemical exfoliation, hydrothermal synthesis, physical vapor deposition, molecular beam epitaxy, and metal-organic chemical vapour deposition [1-5]. Among these methods, chemical vapor deposition (CVD) approach is most promising in terms of scalability and low cost. Here, we report high-quality MoS2and WS2monolayers grown by atmospheric pressure CVD method. The electrical, optical, and Raman characterizations show the high quality of monolayer crystals.