Numerical investigation on the influence of the Soret effect on graphene growth in chemical vapor deposition

The chemical vapor deposition (CVD) is highly feasible, controllable and has great potential in the production of large-area and high-quality graphene. Previous studies have focused on surface reaction mechanisms, but it is equally important to understand how reactants are transported to the substrate. Due to the commonly large temperature gradient in the CVD reactor, the impact of Soret effect on the species transportation is nonnegligible. In this article, the influences of the Soret effect under low pressure and atmospheric pressure conditions are systematically studied using computational fluid dynamics. Due to the difference in the composition of the mixture under these two conditions, the impact of Soret effect on diffusion of the methane molecule is opposite. The diffusion behavior caused by the Soret effect will influence the methane distribution and hence the graphene growth rate. At low pressure, the growth rate will decrease gradually when the substrate position moves along the flow direction. At atmospheric pressure, the Soret effect will increase the carbon deposition rate when the Cu substrate is arranged at the front half of the furnace.