Effect of Substrate symmetry on the dendrite morphology of MoS 2 Film synthesized by CVD

• Published in: Scientific reports 2017-11, Vol.7 (1), p.15166
• Main Authors: Wu, Di, Min, Tai, Zhou, Jian, Li, Chen, Ma, Guobin, Lu, Gaotian, Xia, Minggang, Gu, Zhengbin
• Format: Article
• Language: English
• ISSN: 2045-2322

In van der Waals epitaxial growth, the substrate plays a particularly important role in the crystal morphology. Here, we synthesized MoS by chemical vapour deposition on silicon carbide (SiC). The obtained MoS dendritic crystals show six-fold symmetry, which are different from the conventional triangular shapes on SiO substrate and from those with three-fold symmetry on SrTiO substrate. Interestingly, these MoS dendritic crystals on SiC exhibit an average fractal dimension 1.76, which is slightly larger than the classical Diffusion-limited-Aggregation fractal dimension 1.66. The first principle calculation indicates that the six-fold symmetry of the dendritic MoS is determined by the lattice symmetry of SiC. To further demonstrating the substrate effect, we break the natural six-fold lattice symmetry of SiC (0001) into groove arrays through etching the substrate. And then we successfully synthesized cross-type dendritic crystal MoS with two-fold symmetry. Its average fractal dimension 1.83 is slightly larger than the fractal dimension 1.76 of the previous MoS dendrite with six-fold symmetry. In a word, the symmetry of SiC substrate determined the symmetry and the fractal dimension of the dendritic MoS . This work provides one possibility of inducing the growth orientation of dendritic crystals through controlling the substrate surface symmetry artificially.