Numerical investigation on the effect of gas-phase dynamics on graphene growth in chemical vapor deposition

Chemical vapor deposition (CVD) is a crucial technique to prepare high-quality graphene because of its controllability. In the research, we perform a systematic computational fluid dynamics numerical investigation on the effect of gas-phase reaction dynamics on the graphene growth in a horizontal tube CVD reactor. The research results indicate that the gas-phase chemical reactions in the CVD reactor are in a nonequilibrium state, as evidenced by the comparison of species mole fraction distributions during the CVD process and under chemical equilibrium conditions. The effect of gas-phase reaction dynamics on the deposition rate of graphene under different conditions is studied, and our research shows that the main causes of change in graphene growth rates under different conditions are gas-phase reaction dynamics and active species transport. The results of numerical simulation agree well with the experimental phenomena. The research results also indicate that, for methane, the main limiting factor of graphene growth is the surface kinetic reaction rate. Conversely, for active species, the main limiting factor of graphene growth is species transport. Our research suggests that the growth rate of graphene can be regulated from the perspective of the gas reaction mechanism. This method has theoretical guiding significance and can be extended to the preparation of large-area graphene.