Interfacial interactions at graphene/metal and graphene/dielectric interfaces are likely to profoundly influence the electronic structure of graphene. We present here the first angle-resolved near-edge X-ray absorption fine structure (NEXAFS) spectroscopy study of single- and bi-layered graphene grown by chemical vapor deposition on Cu substrates. The spectra indicate the presence of new electronic states in the conduction band derived from hybridization of the C-π network with Cu d-orbitals. In conjunction with Raman data demonstrating charge transfer, the NEXAFS data illustrate that the uniquely accessible interfaces of 2D graphene are significantly perturbed by surface coatings and the underlying substrate. NEXAFS data have also been acquired after transfer of graphene onto SiO2/Si substrates and indicate that substantial surface corrugation and misalignment of graphene is induced during the transfer process. The rippling and corrugation of graphene, studied here by NEXAFS spectroscopy, is thought to deleteriously impact electrical transport in graphene.
Citation: Journal of Physical Chemistry Letters
Pub Type: Journals