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

In this study, a novel pressure-induced supercritical phase nucleation method is proposed to synthesize monolayer MoS 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 MoO(acac) particles are recrystallized on the substrate via the pressure-sensitive solvent capacity of supercritical CO and these particles are used as growth sites. The size of single-crystal MoS on the substrate is found to be dependent on the wetting area of the pyrolyzed precursor droplets (MoO) on the surface, and the formation of continuous films with high coverage is mainly controlled by the coalescence of MoO 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 MoS and other two-dimensional materials and provide sufficient and valuable evidence for vapor-liquid-solid growth.