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@PHDTHESIS{Yin:1048442,
author = {Yin, Hao},
othercontributors = {Kumpf, Christian and Mayer, Joachim},
title = {{I}nvestigation of 2{D} materials using low energy electron
microscopy ({LEEM})},
school = {RWTH Aachen},
type = {Dissertation},
publisher = {RWTH Aachen University},
reportid = {FZJ-2025-04648},
pages = {pages 1 Online-Ressource : Illustrationen},
year = {2025},
note = {Dissertation, RWTH Aachen, 2025},
abstract = {Low-energy electron microscopy (LEEM) is a versatile and
powerful surface science tool for imaging, structural
analysis and the study of kinetic surface processes such as
molecular island growth, thin film growth and surface
reconstruction. It uses electrons with kinetic energies
below a few hundred electronvolts, often below 10 eV. In
this thesis, LEEM serves as the main technique to support
our research efforts in fabricating 30◦-twisted bilayer
graphene (TBG) and in studying the deposition and
degradation behavior of a cyclic, tire-shaped molecules on a
metal crystal. The first two topics of this thesis build on
previous work from our group that demonstrated the epitaxial
growth of unconventionally oriented monolayer graphene on a
6H-SiC(0001) substrate. In the first topic, LEEM and other
investigation methods were used to characterize the
morphology and electronic properties of such
unconventionally oriented monolayer graphene. The effect of
the preparation temperature on the resulting graphene sample
was highlighted. In the second topic, we achieved and
studied bilayer stacking and twist configurations of
graphene by hydrogen intercalation of the carbon buffer
layer, an intrinsic component between the epitaxial graphene
and the SiC substrate. Hydrogen atoms were successfully
introduced to decouple the buffer layer from the substrate.
The buffer layer was transformed into a true graphene layer
with distinct π-band properties. This intercalation process
was carried out in a stepwise manner, with LEEM being used
to study each step. The deintercalation process was
monitored in situ and in real time. This provided deeper
insights into the mechanisms of hydrogen intercalation and
deintercalation. In the third topic of the thesis, the
deposition behavior of a carbon-based cyclic aromatic
molecule, [6]-cycloparaphenylenes, is investigated using
LEEM in addition to pristine 2D graphene layers.
Interestingly, our observations contradict previous results
obtained by scanning tunneling microscopy. This provides new
insights into the deposition behavior of this type of
molecules on surfaces.},
keywords = {Hochschulschrift (Other) / twisted bilayer graphene (TBG) ;
unconventionally oriented epitaxial graphene ; low energy
electron microscopy (LEEM) ; hydrogene intercalation
(Other)},
cin = {PGI-3},
cid = {I:(DE-Juel1)PGI-3-20110106},
pnm = {5213 - Quantum Nanoscience (POF4-521)},
pid = {G:(DE-HGF)POF4-5213},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2025-07835},
url = {https://juser.fz-juelich.de/record/1048442},
}