In situ crystallization kinetics of two-dimensional MoS2

Developing effective strategies to synthesize 2D materials such as molybdenum disulfide (MoS2) necessitates a fundamental understanding of the thermodynamics and kinetics controlling the nucleation and growth processes. Studying crystallization kinetics of MoS2 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 MoS2 can be directly observed. During isothermal heating we find that nucleation of MoS2 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.