AVS 61st International Symposium & Exhibition
    Novel Trends in Synchrotron and FEL-Based Analysis Focus Topic Tuesday Sessions
       Session SA-TuM

Invited Paper SA-TuM12
Effects of Interfacial Interaction: Electronic Structure of Graphene on Metallic and Insulating Surfaces

Tuesday, November 11, 2014, 11:40 am, Room 312

Session: Characterization of Nanostructured and LD Materials Using Synchrotron-Based Methods
Presenter: Petra Rudolf, University of Groningen, The Netherlands
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The interaction of graphene with substrates and its influence on the electronic properties is of paramount importance for designing novel electronic and optoelectronic devices. However, the capability of disentangling the surface contribution of the support from those of the graphene single layer is a challenging and unresolved problem. In this contribution I shall present results concerning the electronic states of a typical metallic interface, namely graphene/Cu, where the coupling is weak. These results will be compared to the electronic states of suspended graphene and graphene on an insulating substrate.

When the properties of the occupied electronic band structure were investigated by angle-resolved photoelectron spectromicroscopy, we demonstrated that a suspended CVD grown graphene membrane locally shows electronic properties comparable with those of samples prepared by micromechanical cleaving of graphite. CVD grown graphene on the Cu(111) surface was instead found to be slightly doped, while on an insulator surface it was demonstrated to fully preserve the intrinsic properties, implying that the graphene monolayer is totally decoupled as if it were freestanding and not doped.

The unoccupied surface states at the weakly coupled graphene/Cu interface were studied by non-linear angle resolved photoemission spectroscopy. In particular, by comparing the band dispersion of the unoccupied image potential states and the occupied surface states of the interfaces graphene/Cu(111) and graphene/ polycrystalline copper foil, we were able to identify and characterise the Shockley surface state and the n=1 image state of the Cu(111) surface and the symmetric n=1 image state of the single layer of graphene.