Xinyao Zhang

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.

Due to the lack of research on the microscopic evolution process and the formation of step growth patterns for SiC crystals, it is of great importance to deepen the understanding of the epitaxial growth of a SiC vicinal surface from a microscopic point of view. In this study, a three-dimensional lattice kinetic Monte Carlo algorithm was used to study the step flow growth characteristics of SiC crystals. The microscopic evolution of the step flow growth patterns for SiC vicinal surfaces was shown. C and Si were treated as the basic particles, and the net deposition and diffusion of atoms were considered in this model. The periodic boundary conditions were applied along the step edge and the helical boundary conditions were applied in the direction perpendicular to the step. The surface morphology evolution of SiC crystals grown on step substrates was simulated at different growth temperatures, partial deposition fluxes, and terrace widths. The results indicated that the growth patterns of the SiC vicinal surface could be transformed from a step flow growth to a nucleation growth pattern by decreasing the growth temperature, increasing the deposition flux, and increasing the terrace width.