Nanospectroscopy highlights

Corrugations, lattice distortions and charge transfer from adsorbates are the most important sources of electron scattering in graphene. Here, we investigate corrugations in graphene exploiting the multi-technique capabilities offered by a low energy electron microscope (LEEM): real space imaging of the sample morphology over large surface areas (up to several tens micron), with lateral resolution of 10 nm and atomic depth sensitivity, micro-probe low energy electron diffraction (μ-LEED). The short-range roughness of graphene at length scales below 20 nm is quantified by diffraction line-shape analysis, depending on film thickness and interaction with the SiO₂ support.  Due to its reduced stiffness, single-layer graphene shows larger roughness than multi-layers. Because of the absence of an interacting support, suspended graphene displays a

 smoother texture than supported graphene, resulting in a notable narrowing of diffraction spots. Our LEED data suggests that the corrugation in suspended graphene films is influenced by both extrinsic and intrinsic factors, and in particular by adsorbate load and temperature.

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Corrugation in Exfoliated Graphene: An Electron Microscopy and Diffraction Study;
A. Locatelli, K. R. Knox, D. Cvetko, T.O. Menteş, M.Á. Niño, S. Wang, M. B. Yilmaz, P. Kim, R. M. Osgood Jr., and A. Morgante;
ACS Nano, 4, 4879-4889 (2010);
doi: 10.1021/nn101116n.