Effects of Carbide Formation in Graphene Growth

Besides carbon solubility, the carbide formation possibility is another important factor to differentiate various substrate materials in graphene growth. A recent experiment indicates that the formation of transition metal carbides (TMCs) can suppress carbon precipitation. In this study, Mo₂C, a representative of TMCs, is used to study the effects of carbide formation in graphene growth from first principles. Carbon diffusion in Mo₂C bulk turns out to be very difficult and it becomes much easier on the Mo₂C(001) surface. Therefore, carbon precipitation suppression and graphene growth can be realized simultaneously. A direction depended diffusion behavior is observed on the Mo₂C(101) surface, which makes it less favorable for graphene growth compared to the (001) surface.