Precursors: A Quantum Molecular Dynamics Study*

Layered MoS₂ is a promising transition metal dichalcogenides (TMDC) material due to its outstanding physical and chemical properties. Chemical vapor deposition (CVD) is the most effective method to bring this layered TMDC material into mass production. During CVD process, sulfurization of MoO₃ reactants is an essential reaction step to grow atomically thin large MoS₂ area. Recent studies suggested that addition of H₂ gas in this synthesis process could lead to growth of higher-quality MoS₂ monolayers. However, effects of H₂ partial pressure on synthesis of MoS₂ still remain elusive. Here, our quantum molecular dynamics (QMD) simulations reveal that the H₂S/H₂ mixture indeed reduce and sulfurize the MoO₃ flake effectively, when compared with pure H₂S precursors. We also identify key reaction pathways for the reactions of MoO₃ reactants and H₂S/H₂ mixture, which may help experimental synthesis of higher quality MoS₂ layers. We believe our work will make a unique contribution to the scalable growth of 2D TMDC materials for large-scale integration.