Dresden 2020 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 98: Graphene I: Growth, Structure and Substrate Interaction (joint session O/TT)

O 98.3: Vortrag

Donnerstag, 19. März 2020, 11:00–11:15, GER 37

Au intercalation under epitaxial graphene on Ru(0001): the role of graphene edges — •Sebastian Günther¹, Tevfik Onur Mentes², Robert Reichelt¹, Elisa Minussi², Benito Santos², Alessandro Baraldi², and Andrea Locatelli² — ¹TUM, Dept. Chemie, Lichtenbergstr.4, D-85748 Garching — ²Sincrotrone Trieste, AREA Science Park I-34149 Trieste

Au intercalation at the graphene-Ru(0001) interface is investigated at elevated temperature by using low energy electron - and x-ray photoelectron emission microscopy (LEEM/XPEEM). Graphene (g) growth by ethylene decomposition at 1030 K on a Au pre-covered Ru surface pushes the Au adatoms towards the g-free surface area. When instead, evaporating Au on a partly g-covered surface, a modified Stranski-Krastanov growth on Ru with two atomic wetting layers followed by 3D islands is observed. At 970 K the growth follows a precise order: 1)The first wetting Au layer is grown exclusively on the g-free area of the Ru surface. 2)After completion of the Au/Ru layer, Au intercalation below g-flakes sets in. 3)Having completed the g/Au/Ru layer, second wetting Au layer growth ouside the g-covered area takes place. 4)After completion of the Au/Au/Ru layer, intercalation of the second Au layer underneath g sets in. At 970 K, Au is shown not to stick to g-covered surface regions. This crucial finding singles out the g-edges as the only intercalation channel. Chemical maps at different stages during Au growth point to a pronounced kinetic barrier at the g-edges preventing intercalation before the Au monolayer is completed outside the g-covered regions.