Vapor-Liquid-Solid Growth of Site-Controlled Monolayer MoS2 Films Via Pressure-Induc ed Supercritical Phase Nucleation

In this study, a novel pressure-induced supercritical phase nucleation method is proposed to synthesize monolayer MoS2 films, which is promoter free and can avoid contamination of films derived from these heterogeneous promoters in most of the existing techniques. The low-crystallinity and size-controlled MoO2(acac)2 particles are recrystallized on the substrate via the pressure-sensitive solvent capacity of supercritical CO2 and these particles are used as growth sites. The size of single-crystal MoS2 on the substrate is found to be dependent on the wetting area of the pyrolyzed precursor droplets (MoO2) on the surface, and the formation of continuous films with high coverage is mainly controlled by the coalescence of MoO2 droplets. It is enhanced by the increase of the nucleation site density, which can be adjusted by the supersaturation of the supercritical fluid solution. Our findings pave a new way for the controllable growth of MoS2 and other two-dimensional materials and provide sufficient and valuable evidence for vapor-liquid-solid growth.

Automated summary

A novel pressure-induced supercritical phase nucleation method is proposed for synthesizing monolayer MoS2 films, without the need for promoters. The method avoids contamination from heterogeneous promoters seen in existing techniques. The size of MoS2 crystals on the substrate is influenced by the wetting area of precursor droplets, while the formation of continuous films is controlled by the coalescence of droplets. The nucleation site density can be adjusted by the supersaturation of the supercritical fluid solution, providing new possibilities for controlled growth of MoS2 and other two-dimensional materials.