Large-Scale Self-Limiting Synthesis of Monolayer MoS2 via Proximity Evaporation from Mo Films

Abstract

The large-scale synthesis of two-dimensional transition metal dichalcogenides has been actively investigated in recent years. Here, we introduce a nonconventional synthesis process of 2-in.-scale monolayer MoS2 with fairly good uniform coverage, which is based on a unique reaction mechanism due to the self-limiting precursor source in a proximity reaction environment with a distance of only similar to 0.5 mm from the reaction zone. The large-scale MoS2 monolayer film was successfully synthesized using an atmospheric pressure chemical vapor deposition reaction of precursor Mo film in flowing H2S gas through an indirect sulfurization sequence with the oxidized Mo species. The short distance of similar to 0.5 mm provides a unique advantage of uniformity with the self-limiting reaction due to the limited MoO3-x supply. The chemical states of the precursor and deposited films at reaction temperatures were investigated to determine the reaction mechanism of the synthesis. This processing technique is extendable to other two-dimensional materials demanding large-scale coverage with good uniformity.