Synthesis of large-area uniform MoS ₂ films by substrate-moving atmospheric pressure chemical vapor deposition: from monolayer to multilayer

As a typical two-dimensional (2D) semiconducting material, layered transition metal dichalcogenides (TMDCs) show promise in electronics and optoelectronics. To fully realize their potential, cost-effective large-area and layer-number modulated synthesis is highly desired. Here, taking MoS 2 as an example, we demonstrate a layer-by-layer scalable growth of coalesced TMDC films on a moving sapphire substrate by local-feeding atmospheric-pressure chemical vapor deposition. By linear moving of the substrate across the cone-shaped diffusion concentration gradient of Mo-containing species and controlling the moving cycles, continuous MoS 2 films with the thickness from a monolayer up to ~30 layers can be obtained. Compared with the growth on a stationary substrate, the monolayer film grown on a moving substrate shows preferable 2D epitaxial growth with much smoother surface morphology. We believe this can be attributed to the spatial separation of the initial nucleation step and the following 2D ripening process during substrate moving, which is the key to promoting the 2D lateral growth. The results shed light on developing new synthetic strategies toward atomic-thickness-controlled growth of 2D TMDC films in a scalable and efficient process that is suitable for large-area device fabrication.