Effect of grain boundaries in Cu foil on CVD growth of graphene

The effect of the grain boundaries (GBs) in a Cu foil on the CVD growth of graphene was investigated via radiation-mode optical microscopy, which we developed for the real-time observation of growing graphene domains. Although the GBs had the typical width and depth of a few micrometers and hundred nanometers, respectively, they had little effect on the nucleation and the lateral growth of the graphene domains. However, increasing the growth time caused the diffusion of C atoms from the inside of the Cu foil, which was likely to result in additive nucleation and the enhancement of the growth speed at the GBs.