Growth mechanisms of interfacial carbon layers at the epitaxial Al₂O₃(0001)/Cu(111) interface as application for epitaxial film lift-off

The growth of interfacial carbon (IFC) layers at the epitaxial sapphire/metal interface could unlock the transfer process for large-scale epitaxial thin films, such as graphene. To assess the feasibility of the application of IFC, understanding of the growth mechanisms of IFC layers at the epitaxial metal/sapphire interface is required. In this study, atmospheric pressure chemical vapor deposition is used to directly synthesize wafer-scale multilayer carbon at the interface between the Al2O3(0001) substrate and epitaxial Cu(111) layer. Characterization by Raman spectroscopy, AFM, and XRD, indicates the IFC layers exhibit low defect density and sp(2) bonding character. Furthermore, IFC as thick as 100 nm could be synthesized. The effect of the partial pressure of reaction gases is systematically investigated, and a growth mechanism is proposed based supported by experimental observations and simulation results. Finally, a mechanical lift-off of a Cu(111) film with the aid of the IFC layer is demonstrated as a proof-of-concept application.