Growth of wafer scale continuous monolayer WS2 film with millimeter grain size

WS2 has gained great attention as atomically thin semiconductors for nanoscale transistors. Wafer scale WS2 films can be obtained by chemical vapor deposition (CVD). But the grain size was only several to tens of micrometers which resulted in a large amount of grain boundaries in the film. The grain boundaries will cause carrier scattering of the film. Wafer scale growth with millimeter grain size is still challenging. In this study, we propose a novel growth method to realize 2-inch continuous monolayer WS2 films with grain size in millimeters. To our knowledge, this is the first report on wafer scale continuous monolayer WS2 films with such grain size. Both Raman mapping and atom force microscope (AFM) imaging reflect a high uniformity of the film. Our research provides an effective way to grow high quality wafer scale continuous monolayer WS2 and other two-dimensional transition metal dichalcogenides (TMDCs) films with large grain size.