Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 33: Poster Graphene: Electronic Structure and Excitations
O 33.11: Poster
Tuesday, March 18, 2025, 13:30–15:30, P3
Twisted Bilayer Graphene by Hydrogen Intercalation — •Hao Yin1,2, Andrei Matetskii1, Frank Stefan Tautz1,2, François C. Bocquet1, and Christian Kumpf1,2 — 1Peter Grünberg Institut (PGI-3), FZ-Jülich, Germany — 2RWTH Aachen University, Aachen, Germany
Quasi-free-standing twisted bilayer graphene (TBLG) with a 30∘ twist angle is achieved on a 6H-SiC(0001) surface via hydrogen intercalation of the zeroth-layer graphene (ZLG). Initially, 0∘-rotated monolayer graphene is prepared using the surfactant-mediated epitaxial growth method [PRL 125, 106102 (2020)]. The processes of hydrogen intercalation and deintercalation were investigated using Low Energy Electron Microscopy (LEEM), with intercalation conducted stepwise, while deintercalation was monitored in real time. Our results provide valuable insights into the mechanisms underlying hydrogen intercalation and deintercalation.
A sharp reaction front was observed, aligned parallel to the step edges, suggesting that hydrogen atoms migrate beneath the ZLG from surface discontinuities, such as step edges or defects.
Deintercalation, taking place 200∘C above the intercalation temperature, was significantly faster (within one minute) and occurred uniformly, as indicated by the homogeneous brightness changes in deintercalated regions. This implies a much faster diffusion of H under the TBLG at this temperature, or possibly that H atoms are able to penetrate through the graphene layers.
Keywords: Twisted Bilayer Graphene; LEEM; Hydrogen Intercalation; Deintercalation