The Effect of Catalytic Copper Pretreatments on CVD Graphene Growth at Different Stages.

The controllable synthesis of high-quality and large-area graphene by Chemical Vapor Deposition (CVD) remains a challenge nowadays. The massive grain boundaries in graphene grown on polycrystalline Cu by CVD significantly reduce its carrier mobility, limiting its application in high-performance electronic devices. Here, We confirmed that the synergetic pretreating Cu with electropolishing and surface oxidation is a more efficient way to further suppress the graphene nucleation density (GND) and to accelerate the growth rate of graphene domain by CVD. With increasing the growth time, we founded that the increasing number of the GND and growth rate of graphene domain were both decreasing during the whole CVD process when the Cu surface was not oxidized. By contrast, they were kept growing over time when the Cu surface was pre-oxidized, which suggested that the change trends of the effects on the GND and growth rate between Cu surface morphology and oxygen were opposite in CVD process. In addition, not only the domain shape but also the number of graphene domain layers were impacted as well, and a large number of irregular ellipse graphene wafers with dendritic multilayer emerged when the Cu surface was oxidized.