Bilayer Graphene Growth via a Penetration Mechanism

From both fundamental and technical points of view, precise control of the layer number of graphene samples is very important. To reach this goal, atomic-scale mechanisms of multilayer graphene growth on metal surfaces should be understood. Although it is a geometrically favorable pathway to transport carbon species to interface and then form a new graphene layer there, penetration of a graphene overlayer is not a chemically straightforward process. In this study, the possibility of different active species penetrating a graphene overlayer on Cu(111) surface is investigated by first-principles calculations. It is found that carbon atom penetration can be realized via an atom-exchange process, which leads to a new graphene growth mechanism. Based on this result, a bilayer graphene growth protocol is proposed to obtain high-quality samples. Such a penetration possibility also provides great flexibility for designed growth of graphene nanostructures.