Synthesis and Characterization of Large-Area and Highly Crystalline Molybdenum Disulphide Atomic Layer by Chemical Vapor Deposition

The Isolation of few-layered transition metal dichalcogenides has mainly been performed by mechanical and chemical exfoliation with very low yields. in particular, the two-dimensional layer of molybdenum disulfide (MoS2) has recently attracted much interest due to its direct-gap property and potential application in optoelectronics and energy harvesting. However, the synthetic approach to obtain high-quality and large-area MoS2 atomic thin layers is still rare. In this account, a controlled thermal reductionsulfurization method is used to synthesize large-MoOx thin films are first deposited on Si/SiO2 substrates, which are then sulfurized (under vacuum) at high temperatures. Samples with different thicknesses have been analyzed by Raman spectroscopy and TEM, and their photoluminescence properties have been evaluated. We demonstrated the presence of single-, bi-, and few-layered MoS2 on as-grown samples. It is well known that the electronic structure of these materials is very sensitive to the number of layer, ranging from indirect band gap semiconductor in the bulk phase to direct band gap semiconductor in monolayers. This synthetic approach is simple, scalable, and applicable to other transition metal dichalcogenides. Meanwhile, the obtained MoS2 films are transferable to arbitrary substrates, providing great opportunities to make layered composites by stacking various atomically thin layers.