Nonthermal Plasma-Enhanced Chemical Vapor Deposition of Two-Dimensional Molybdenum Disulfide

Molybdenum disulfide (MoS2) is being studied for a wide range of applications including lithium-ion batteries and hydrogen evolution reaction catalysts. In this paper, we present a single-step nonthermal plasma-enhanced chemical vapor deposition (PECVD) process for the production of two-dimensional MoS2. This method provides an alternative route to established CVD and plasma synthesis routes. The approach presented here synthesizes films in only a few minutes using elemental sulfur (S-8) and molybdenum pentachloride (MoCl5) as precursors. Deposition utilizes a nonthermal inductively coupled plasma reactor and temperatures around 500 degrees C. Film growth characteristics and nucleation are studied as a function of precursor concentrations, argon flow rate, plasma power, and deposition time. Few-layer two-dimensional (MoS2) films were formed at low precursor concentrations. Films with nanoparticle-like features were formed when the precursor concentration was high. Noncontinuous nonstoichiometric films were found at low plasma power, while high plasma power led to continuous films with good stoichiometry. The vacancies and defects in these films may provide active sites for hydrogen evolution.