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 (Delta T >= 200 degrees 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.