Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 18: Poster Monday: 2D Materials 1
O 18.4: Poster
Monday, September 5, 2022, 18:00–20:00, P4
twisted graphene on Ir(111) and SiC(0001) studied by SPA- LEED — •mohammad tajik1, christian brand1, birk finke1, karim omambac1, laurenz kremeyer1, frank meyer zu heringdorf1,2, and michael horn-von hoegen1,2 — 1Universität Duisburg-Essen — 2center for nanointegration duisburg-essen
when graphene is placed on a crystalline surface, the periodic structures within the layers superimpose and a moiré superlattices form. Small lattice rotations between the 2D-layer and the substrate strongly modify the moiré superlattice, upon which many electronic, vibrational, and chemical properties depend. Here we report on such structural modification of epitaxial graphene grown on metallic Ir(111) and semiconducting SiC(0001) surfaces. The spontaneous reorientation in the degree- and sub-degree-range of graphene on Ir(111) depends on the substrate temperature during growth. This effect is described by a 2D coincidence network favored by strain reduction together with the dissimilar thermal expansion of the substrate and graphene. For graphene on SiC(0001) only the oriented R0* phase is found due to the higher bonding strength to the substrate. Upon H and Sn intercalation this interaction can be reduced such that the graphene layer is lifted from the substrate. Finally, we present a detailed analysis of an unusually broad diffraction background found for graphene and hex-BN on both substrates.