Synthesis of High Quality Monolayer Transition Metal Dichalcogenides using Direct Liquid Injection

In recent years, interest in monolayer transition metal dichalcogenides (TMDs) has rapidly increased, spurred by the possibility for integration into a variety of technologies such as photodetection, flexible electronics, and chemical sensing. While fundamental investigations can be performed on exfoliated flakes or chemical vapor deposition synthesized isolated islands, the limited size resulting from these techniques poses a significant barrier for implementation of TMDs in technological applications. To overcome these obstacles, new synthesis avenues should be explored. Here, we outline a novel technique that utilizes a commercially available Anneal Sys growth chamber equipped with direct liquid injection (DLI) heads for all precursors. The use of liquid, rather than solid precursors, provides fine control of both metal and chalcogen precursors leading to the synthesis of monolayer MoS₂ across cm² areas. Photoluminescence, Raman and XPS are used to evaluate DLI grown MoS₂, and indicate high quality material, with metrics comparable to or better than exfoliated and chemical vapor deposition grown MoS₂.