Edge-driven adatom kinetics in graphene nanoribbon growth on Cu(111)

Using first-principles density functional theory calculations, we investigate how the finite width of graphene nanoribbons on Cu(111) affects the kinetics of carbon adatoms during nanoribbon growth. Our calculations reveal that edge-induced deformations of the metal substrate, coupled with the curvature of the graphene nanoribbon, create a spatially varying potential landscape. This landscape introduces an additional, width-dependent kinetic barrier for adatom attachment from the bare Cu surface and a drift of adatoms from the nanoribbon center toward its edges. Attachment from the graphene surface is shown to occur preferentially via a low-barrier push-out mechanism involving concerted motion of edge atoms.