Effect of chemical vapor deposition system parameters on 2B-Mo2 growth: A comparative analysis of low and atmospheric pressure system

In this study, the synthesis of two-dimensional molybdenum carbide (Mo2C) crystals was systematically investigated using a low-pressure chemical vapor deposition (LPCVD) system, while a direct comparative study was also conducted with an atmospheric-pressure CVD (APCVD) system. In the literature, Mo2C growth has been predominantly carried out under atmospheric-pressure conditions, and successful synthesis of 2D Mo2C under low-pressure conditions has been very limited. Therefore, this study provides a significant original contribution by demonstrating the successful growth of high-quality Mo2C crystals under low-pressure conditions. First, SiO2 contamination originating from quartz components was identified and eliminated through a redesigned sample geometry. In the growth experiments performed with different Cu foil thicknesses (10–250 µm), it was observed, consistent with the literature, that increasing Cu thickness led to a reduction in Mo2C crystal thickness and a noticeable improvement in morphology. Process comparisons revealed that the PR2 route in the LPCVD system provided the most favorable conditions in terms of crystal quality, low contamination, and homogeneous morphology. A 15-minute graphene pre-growth followed by a 32-minute Mo2C growth yielded uniformly distributed, thin, hexagonally shaped crystals with high structural regularity. In conclusion, this study established a reference parameter map for 2D Mo2C growth in low-pressure systems and, through direct comparison with the atmospheric-pressure system, presented the first comprehensive benchmark in the literature for such growth.