Hydrogen Addition for Centimeter-Sized Monolayer Tungsten Disulfide Continuous Films by Ambient Pressure Chemical Vapor Deposition

Monolayer tungsten disulfide (WS2) offers great prospects for use in optoelectronic devices due to its direct bandgap and high photoluminescence intensity. Here, we show how the controlled addition of hydrogen into the chemical vapor deposition growth of WS2 can lead to the formation of centimeter scale continuous monolayer films at ambient pressure without the need for seed molecules, specially prepared substrates, or low pressure vacuum systems. Modifications of the reaction conditions, including growth time and hydrogen to argon ratio, allow for control over the domain size, film coverage, and film uniformity of the prepared WS2 film. The combined control of hydrogen and a double-furnace system enables an increases in the growth rate of WS2, which results in fully merged films with cm(2) coverage and reduced multilayer content. Field effect transistors are fabricated to demonstrate that WS2 has high quality for electronic applications. Our ambient pressure chemical vapor deposition reaction is simple and efficient, ideal for mass-production of large area monolayer WS2.