Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Graphene: Growth, Substrate Interaction, Intercalation, and Doping

O 41.5: Vortrag

Mittwoch, 7. September 2022, 11:30–11:45, S052

Quasiparticle Interference Effects Revealed in Potassium-Intercalated Epitaxial Monolayer Graphene — Tobias Huempfner, •Felix Otto, Roman Forker, and Torsten Fritz — Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany

Epitaxial graphene is known for its fascinating physical properties, such as a linear dispersion at the K point, an anomalous quantum Hall effect and even superconductivity. These effects are based on the unique electronic structure of graphene, which can be tuned, e.g., by intercalation of metals. In this study, we scrutinize samples of epitaxial monolayer graphene (EMLG) on SiC(0001) intercalated with potassium by means of local and area-averaging experimental methods at low temperatures. For the highest accessible K concentration we find a highly ordered (2×2) superstructure that the K atoms form below the uppermost graphene layer. Further, we observe that the K atoms also reside below the buffer layer of the EMLG on SiC(0001) sample that is located between the quasi-freestanding graphene sheet and the SiC substrate. This causes an effective decoupling of the buffer layer and a transformation to K-intercalated epitaxial bilayer graphene (EBLG). This configuration promotes strong n-doping of the graphene sheets, where besides a rigid shift of the Dirac bands to higher binding energies also filling of two parabolic interlayer bands is observed.