| AVS 59th Annual International Symposium and Exhibition | |
| Graphene and Related Materials Focus Topic | Tuesday Sessions |
| Session GR+AS+NS+SP+SS-TuA |
| Session: | Graphene Characterization Including Microscopy and Spectroscopy |
| Presenter: | J.D. Emery, Northwestern Univ. |
| Authors: | J.D. Emery, Northwestern Univ. B. Detslefs, European Synchrotron Radiation Fac., France H.J. Karmel, Northwestern Univ. V.D. Wheeler, U.S. Naval Research Lab J.M.P. Alaboson, Northwestern Univ. L.O. Nyakiti, U.S. Naval Research Lab R.L. Myers-Ward, U.S. Naval Research Lab C.R. Eddy, Jr., U.S. Naval Research Lab D.K. Gaskill, U.S. Naval Research Lab M.C. Hersam, Northwestern Univ. J. Zegenhagen, European Synchrotron Radiation Fac., France M.J. Bedzyk, Northwestern Univ. |
| Correspondent: | Click to Email |
The implementation of graphene into next-generation electronics will require production high-quality graphene at the wafer scale. One promising route for the production of wafer-scale graphene is to grow epitaxial graphene (EG) via thermal decomposition of Si-terminated SiC (SiC(0001)). This method produces high-quality EG, but is accompanied by the formation of the so-called "buffer layer" at the interface, which is known to affect the electronic properties of the graphene. Despite numerous efforts to determine the nature of the buffer layer, debate persists concerning its atomic and chemical structure. Here, we use the X-ray Standing Wave (XSW) technique to create a precise chemically-sensitive description of the distributions of Si and C at the interface. This technique, which combines X-ray scattering and X-ray Photoelectron Spectroscopy (XPS), is capable of locating coherent distributions of chemically distinct species above a single crystal surface. This allows for a more detailed description of the interface than those afforded by scattering or XPS alone. Our analysis shows that the buffer layer, which is present in both UHV and furnace-grown EG/SiC(0001), contains no substantial non-bulk or oxide silicon component, and is thus purely carbon. We identify two chemically distinct carbon species within the interface layer, each with a distinct location above the Si-terminated surface, and report their positions and distributions with sub-angstrom precision. These results help to clarify long-standing uncertainties about the interfacial structure of graphene/SiC(0001). Further, we also highlight the potential for XSW with XPS as a valuable tool in the structural determination of complex interfaces, such as functionalized, doped, or intercalated epitaxial graphene.