In situ crystallization kinetics of two-dimensional MoS ₂

Developing effective strategies to synthesize 2D materials such as molybdenum disulfide (MoS 2 ) necessitates a fundamental understanding of the thermodynamics and kinetics controlling the nucleation and growth processes. Studying crystallization kinetics of MoS 2 with conventional synthesis methods, such as chemical vapor deposition, is challenging because there is a complex set of thermally-activated events happening simultaneously. By combining high-throughput experimentation with in situ Raman spectroscopy we show that the migration-limited crystallization kinetics of MoS 2 can be directly observed. During isothermal heating we find that nucleation of MoS 2 happens rapidly and that the crystallization rate follows an Arrhenius temperature relationship, yielding an energy barrier of 1.03 eV/atom. The relationship between temperature, crystal quality, and layer orientation is determined with transmission electron microscopy and Raman spectroscopy, revealing that elevated crystallization temperatures improve crystal quality and reduce defect formation.