Vapor-Liquid-Solid Growth of Site-Controlled Monolayer MoS 2 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 2 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 2 (acac) 2 particles are recrystallized on the substrate via the pressure-sensitive solvent capacity of supercritical CO 2 and these particles are used as growth sites. The size of single-crystal MoS 2 on the substrate is found to be dependent on the wetting area of the pyrolyzed precursor droplets (MoO 2 ) on the surface, and the formation of continuous films with high coverage is mainly controlled by the coalescence of MoO 2 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 2 and other two-dimensional materials and provide sufficient and valuable evidence for vapor-liquid-solid growth.