From Cr carbide to Cr oxide through a graphene layer

Interfacing graphene with ultrathin oxide films is a crucial step towards its integration in novel electronic devices. However, obtaining two-dimensional oxide films on top of graphene is a formidable task, as the extremely low surface free energy of the graphitic substrate favors the formation of oxide clusters. Here, we demonstrate that the oxidation of a Cr carbide film intercalated between graphene and a Ni(1 1 1) substrate triggers the de-intercalation of Cr atoms, which form a continuous and atomically flat Cr oxide wetting layer on top of graphene. Microscopic and spectroscopic analyses demonstrate that the process affects marginally the structural integrity and electronic properties of graphene with respect to the pristine graphene/Ni(1 1 1) case. These findings show a new method to obtain high-quality graphene/Cr oxide interfaces. In perspective, these well-defined junctions could be used to finely control the electrical conductivity of graphene through an insulating oxide gate.