Graphene Islands on Cu Foils: The Interplay between Shape, Orientation, and Defects

We have observed the growth of monolayer graphene on Cu foils using low energy electron microscopy On the (100) textured surface of the foils four lobed 4 fold symmetric islands nucleate and grow The graphene in each of the Four lobes has a different crystallographic alignment with respect to the underlying Cu substrate These polycrystalline islands arise from complex heterogeneous nucleation events at surface imperfections The shape evolution of the lobes is well explained by an angularly dependent growth velocity Well ordered graphene forms only above 790 degrees C Sublimation induced motion of Cu steps during growth at this temperature creates a rough surface where large Cu mounds form under the graphene islands Strategies for improving the quality of monolayer graphene grown on Cu foils must address these fundamental defect generating processes