Defect Healing of Chemical Vapor Deposition Graphene Growth by Metal Substrate Step

The evolution of carbon structures and the kinetics of graphene nucleation on nickel step surfaces are investigated by classical molecular dynamics simulations and density functional theory calculations. It is found that the evolution mechanism of C structures on the step surface is the same as that on the flat terrace when no substrate Ni atom is pulled out of the surface. But the defects involved with the pulled-out Ni atoms can be efficiently healed with the assistance of the step atoms on the step surface, while they are rather difficult to be healed on the terrace. Compared with the terrace, the step significantly lowers the healing barrier of the defect involved with the pulled-out Ni atom and therefore results in a very fast healing of the defect. These results demonstrate that the presence of the step is beneficial to synthesize better graphene for chemical vapor deposition growth on Ni substrate.