Phase-Field Modeling of Chemical Vapor-Deposited 2D MoSe₂ Domains with Varying Morphology for Electronic Devices and Catalytic Applications

Two-dimensional (2D) crystalline growth of transition metal dichalcogenides (TMDs) by atmospheric pressure chemical vapor deposition (APCVD) is highly sensitive to any changes in growth parameters. At an optimized growth temperature and transition metal flux, 2D compact domains grow primarily triangular/hexagonal in shape that transform into dendritic structures at higher transition metal flux. With changes in the local flux (or, local chalcogen-to-transition metal vapor ratio), domain morphologies on the substrate vary with distance for locations away from the center. In this work, phase field simulations are carried out to emulate experimentally observed morphology evolution as a function of transition metal flux. Our model demonstrates the critical roles of precursor flux and attachment time in controlling the domain morphologies which is further established by fractal dimension analysis. Evolution of patterns simulated as a function of flux and attachment time can help to identify more precise combination of growth parameters leading to a specific growth mode. Consistent with the experimental observations, the model also reproduces the interaction among multiple domains. Our findings could be useful for achieving controlled growth of 2D domains with desired shape (compact or dendritic) as required for the next-generation electronic and optoelectronic devices, and efficient catalytic applications.