Graphene on Ru(0001) Moire Corrugation Studied by Scanning Tunneling Microscopy on Au/Graphene/Ru(0001) Heterostructures

R Cortes and DP Acharya and CV Ciobanu and E Sutter and P Sutter, JOURNAL OF PHYSICAL CHEMISTRY C, 117, 20675-20680 (2013).

DOI: 10.1021/jp406415h

Two-dimensional Au islands of different thicknesses grown on graphene/Ru(0001) were used to study the corrugation of the moire structure of graphene/Ru(0001) and discriminate between its mainly structural or electronic character. A comparison of the apparent corrugation measured by scanning tunneling microscopy (STM) for different Au thicknesses with results of elasticity theory equations applied to a gold film over a corrugated substrate shows that the corrugation observed for the graphene/Ru(0001) moire is of structural nature rather than electronic. STM showed a large value for the corrugation of the first Au monolayer on graphene/Ru(0001), similar to 1.7 angstrom; using density functional theory calculations, we explain this large corrugation of the Au monolayer as the result of a strong (weak) binding of the Au layer at the valley (hill) regions of the graphene/Ru(0001) moire structure and infer an actual corrugation of the graphene/Ru(0001) moire structure of similar to 1.2 angstrom from the measured corrugation of the Au monolayer.

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