Berlin 2018 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 23: Graphene: Adsorption, Intercalation and Doping I (joint session O/TT)
TT 23.3: Talk
Monday, March 12, 2018, 15:30–15:45, MA 043
Sulfur intercalation underneath single-layer graphene on Ru(0001) — •Lars Buss1, Moritz Ewert1,2, Jens Falta1,2, and Jan Ingo Flege1,2 — 1Institute for Solid State Physics, University of Bremen, Germany — 2MAPEX Center for Materials and Processes, University of Bremen, Germany
The strong binding of epitaxially grown single-layer graphene to a wide range of transition metals has detrimental influence on its electronic properties. However, by lifting the interlayer coupling, e. g., via intercalation routes, its unique electronic properties can be restored. We have investigated the interaction of sulfur with single-layer graphene grown on Ru(0001) by ethylene exposure under UHV conditions with in situ low-energy electron microscopy (LEEM) and micro-diffraction (µLEED). At elevated temperature and under dimethyl disulfide background pressure, we observe that sulfur intercalates through the open edges of the graphene islands and proceeds along the substrate steps. Prolonged exposure to sulfur is also seen to induce cracking of the graphene islands perpendicular to the substrate steps, consistent with substantial relief of tensile strain after successful sulfur insertion underneath the graphene. This interpretation is backed by µLEED patterns collected from single graphene islands that consist of an incoherent superposition of the LEED patterns observed individually for pure graphene as well as pure sulfur adsorption on the clean Ru surface, indicating that the graphene layer is virtually decoupled from the substrate.