Computational modelling of the synthesis of MoS₂ monolayers

The emergence of atomically thin 2D materials of semiconducting (transition metal dichalcogenides, TMDs, e.g. MoS₂ , WS₂) layers has opened new avenues for scientific and technological advancement in the area of ultrathin electronic and optoelectronic devices [1]. Chemical vapor deposition (CVD) is known as effective method to synthesize monolayers of TMDs by using solid precursors [2] or metal-organic CVD (MOCVD) [3]. One of the most important open questions of the synthesis of different TMDs monolayers is the reaction mechanism, which can be studied by computational modelling of the synthesis process. While the other research efforts were targeted at the development of the thermodynamic models, here we concentrate on both thermodynamic and kinetic approaches of modelling of synthesis processes of MoS₂ monolayers. We study CVD with solid precursors (S and MoO₃) and MOCVD with H₂S and Mo(CO)₆ precursors. Thermodynamic modeling provides analysis of the influence of chemical composition of the reactants, carrier gas (pure Ar or Ar/H₂ mixture), temperature and pressure of the reaction products. Kinetic approach allows us to estimate the reaction rate and to optimize the gas flow rate, which especially relevant for MOCVD cold-wall reactor. In this way we analyze optimal parameters for the synthesis of MoS₂ by CVD and MOCVD. The reported study was funded by the DAAD, program «Mikhail Lomonosov II», project № 16.13419.2019/13.2.