Dresden 2020 – wissenschaftliches Programm
Die DPG-Frühjahrstagung in Dresden musste abgesagt werden! Lesen Sie mehr ...
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 26: Poster Session - Graphene: Growth, Structure and Substrate Interaction
O 26.4: Poster
Montag, 16. März 2020, 18:15–20:00, P1A
Twisted Graphene on Ir(111) and SiC(0001) Studied by SPA-LEED — •Christian Brand1, Birk Finke1, Karim M. Omambac1, Laurenz Kremeyer1, Frank-J. Meyer zu Heringdorf1,2, and Michael Horn-von Hoegen1 — 1Universität Duisburg-Essen and CENIDE, Germany — 2ICAN, Duisburg, Germany
When graphene is placed on a crystalline surface, the periodic structures within the layers superimpose and moiré superlattices form. Small lattice rotations between the two materials in contact strongly modify the moiré superlattice, upon which many electronic, vibrational, and chemical properties depend. Here we report on the structural manipulation 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. The resulting effective compressive biaxial pressure is more easily accommodated in graphene by small rotations rather than by compression [Nano Lett. 19, 4594 (2019)]. 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 [Phys. Rev. B 110, 155307 (2019)].