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@PHDTHESIS{Sforzini:838780,
author = {Sforzini, Jessica},
title = {{T}he influence of the substrate on the structure and
electronic properties of carbon-based 2{D} materials},
volume = {153},
school = {RWTH Aachen},
type = {Dr.},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2017-07304},
isbn = {978-3-95806-255-9},
series = {Schriften des Forschungszentrums Jülich. Reihe
Schlüsseltechnologien / Key Technologies},
pages = {XIII, 143 S.},
year = {2017},
note = {RWTH Aachen, Diss., 2017},
abstract = {The exploration of two-dimensional (2D) materials, such as
graphene, has become the hottest research of interest in
recent years because they offer the possibility to create
more efficient, smaller and cost-effective nano-devices. In
order to realize potential applications of 2D materials in
the areas of electronics and optoelectronics, there are many
challenges associated with their electronic and structural
behavior, which require the understanding of the
interactions at 2D materials interfaces. With this in mind,
the goal of this thesis was to assess interactions between
various 2D layers and substrates, of interest for both
fundamental studies and industrial applications, by studying
the modification of the layer electronic and structural
properties in relation to the supporting substrate using
different surface science techniques. In particular,
interactions residing at graphene/6H-SiC(0001) interfaces
were considered. At first, a new approach used to gauge the
strength of these interactions was presented based on the
determination of the graphene adsorption height with respect
to the H-intercalated SiC substrate. By comparing this value
with the graphene vertical distance of different
graphene/substrate systems, we found H-intercalated graphene
(H-QFMLG) free of interactions besides van der Waals,
indicating that the effect of the underlying H-intercalated
SiC on graphene was almost non existent. The influence of
this substrate on the structural and electronic properties
of graphene was further investigated upon nitrogen doping in
comparison to the carbon buffer layer terminated SiC in
epitaxial graphene (EMLG). The outcome was that both
graphene layers showed a similar n-type carrier increase but
a dissimilar concentration and variety of dopants
substituted into the graphene layers leading to the main
conclusion that the effective doping of graphene was
surprisingly dependent on the supporting material. In the
case of H-QFMLG, the nitrogen dopants were found partially
replacing the hydrogen intercalation at the interface, which
in turn became N-doped contributing to the graphene doping
(’proximity doping’) but degrading the graphene layer in
terms of buckling and interface interactions. On
thecontrary, the buffer layer in EMLG was found inert
allowing a multicomponent substitution of the nitrogen
dopants into graphene. Howver, ths was not the case for
boron-doped EMLG, for which boron was found in one chemical
configuration and in both buffer layer and graphene. In the
last part of the thesis, the focus was laid on the study of
physical phenomena that occur at organic/metal interfaces.
Specifically, the molecular symmetry reduction (from the D4h
symmetry group) via degeneracy lifting of the platinum- and
palladium-phthalocyanine/Ag(111) complexes was investigated
using vibrational spectroscopy. Because of the presence of
an interfacial dynamical charge transfer, some vibrational
peaks showed a Fano-type line shape. By their assignment to
vibrational modes which were infrared active only in the
C$_{2v}$ symmetry group, we proved that a preferential
charge transfer from the Ag surface into one of the
originally doubly degenerate lowest unoccupied molecular
orbitals took place, i.e. the electronic degeneracy was
lifted and the molecule-surface complex acquired the twofold
symmetry.},
cin = {PGI-3},
cid = {I:(DE-Juel1)PGI-3-20110106},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
urn = {urn:nbn:de:0001-2017120701},
url = {https://juser.fz-juelich.de/record/838780},
}