Decoupling of CVD graphene by controlled oxidation of recrystallized Cu

Large-area graphene grown by chemical vapour deposition (CVD) is promising for applications; however, the interaction between graphene and the substrate is still not well understood. In this report, we use a combination of two non-destructive characterization techniques, i.e., electron backscatter diffraction (EBSD) and Raman mapping to locally probe the interface between graphene and copper lattices without removing graphene. We conclude that the crystal structure of the Cu grains under graphene layers is governed by two competing processes: (1) graphene induced Cu surface reconstruction favoring the formation of Cu(100) orientation, and (2) recrystallization from bulk Cu favoring Cu(111) formation. The underlying Cu grains, regardless of reconstruction or recrystallization, induce a large hydrostatic compression to the graphene lattice. Interestingly, the strong interaction could be decoupled by allowing the intercalation of a thin cuprous oxide interfacial-layer. The Cu₂O layer is mechanically and chemically weak; hence, graphene films can be detached and transferred to arbitrary substrates and the Cu substrates could be re-used for graphene growth.