Controlled Fractal Growth of Transition Metal Dichalcogenides

We report controlled fractal growth of atomically thin transition metal dichalcogenides (TMDCs) by chemical vapor deposition, with morphological evolution from dendritic to triangular. Based on experimental observations, we tuned several important growth parameters, including the relaxation rate, adhesion coefficient, diffusion anisotropy and growth time to fabricate TMDCs with controllable fractal dimensions. Furthermore, a model based on the steps of nucleation, diffusion limited aggregation, and relaxation, was proposed to explain the morphological evolution. The computational simulation based on this model yielded good agreements with the experiments results. Our study sheds light on the growth mechanism of TMDs, which is fundamental to improving controllability of growth.