Lattice kinetic Monte Carlo method on fractal growth of transition metal dichalcogenides

Transition metal dichalcogenides (TMDs) are widely used in semiconductor materials, lubricants, catalysts, and various other applications due to their exceptional physical and chemical properties. During the chemical vapor deposition growth process of TMDs, triangular or hexagonal domains can be generated under appropriate conditions, and TMDs may also exhibit fractal growth and manifest diverse morphologies, such as irregular fractals, dendrites, and semicompact structures. In order to thoroughly investigate the phenomenon of fractal growth, a lattice kinetic Monte Carlo model has been developed to quantitatively characterize the morphology of tungsten diselenide (WSe2) on a graphene substrate and simulate its growth process. First, the deposition rate and diffusion rate of atoms are calculated by using the energy parameter, and then, the atomic kinetic behaviors of atoms are simulated. Subsequently, the coordinates of all adsorbed atoms during the growth process are obtained, and, thus, the morphology of the domain is obtained. Then, their morphological characteristics are further analyzed including the nucleation conversion rate, radius of gyration, and fractal dimension. The results indicate that the growth temperature has a significant impact on the fractal type of domain, and the deposition flux has a significant impact on the branching part of the domain. The increase in the temperature leads to a more compact atomic distribution within the domain, resulting in the changes in the overall morphology. Similarly, an increase in the deposition flux leads to an increase in the number of atoms in the branches of the domain.