Roles of Hydrogen Partial Pressure in Controlled Sulfidation and Nucleation Process of Molybdenum Oxide*

Molybdenum disulfide (MoS₂), a direct-bandgap 2 dimensional material, is a promising candidate for future electronics applications due to its unique electronic properties, for which thorough understanding of synthesis processes is indispensable. Experimental studies on the growth of MoS₂ via chemical vapor deposition (CVD) revealed that single-layer MoS₂ nanocrystals growth could be controlled by gas composition in reaction chamber. Here, we use quantum and reactive molecular dynamics simulations to investigate the effects of varying H₂ partial pressure in the CVD growth process of MoS₂. Simulation results reveal key hydrogen-catalyzed reaction pathways and intermediate products. We also quantify the effects of H₂ composition on the sulfidation and nucleation rates. These atomistic mechanisms not only explain experimental results but also shed light on controlled growth of MoS₂ monolayers.