Exploring MoS2 Growth: A Comparative Study of Atmospheric and Low-Pressure CVD

Transition-metal dichalcogenides (TMDs), in particular MoS₂, have garnered a lot of interest due to their unique properties and potential applications. Chemical vapor deposition (CVD) is generally used to synthesize 2D films of MoS₂. The synthesis of MoS₂ is highly sensitive to growth parameters such as temperature, pressure, flow rate, precursor ratio, etc. Though there are several accounts of MoS₂ synthesis via atmospheric-pressure CVD (APCVD) and low-pressure CVD (LPCVD), there is a lack of a comparative analysis between the two methods, which could potentially offer a better perspective on the growth of MoS₂. This work systematically investigates the growth of MoS₂ under APCVD and LPCVD conditions. The APCVD growth of MoS₂ is found to be diffusion-limited, leading to the characteristic triangular morphology, while the LPCVD growth is reaction-limited. The enhanced mass flux in LPCVD, even at much lower temperatures (ΔT ≥ 200 °C), increases the nucleation density, resulting in a continuous polycrystalline film covering the entire substrate. This comparative study provides a better insight into understanding the crystallization and growth of MoS₂, which can also be extended to other TMDs.