posted on 2020-03-19, 13:33authored byHong Je Choi, Ye Seul Jung, Seung Min Lee, Sojung Kang, Dongjea Seo, Hangyel Kim, Heon-Jin Choi, Gwan-Hyoung Lee, Yong Soo Cho
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 ∼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 ∼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.