Book/Dissertation / PhD Thesis

FZJ-2020-03259

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Morphology and electronic structure of graphene supported by metallic thin films

Jugovac, M. (Corresponding author)FZJ*

2020
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-498-0

Please use a persistent id in citations: http://hdl.handle.net/2128/25876

Abstract: The increasing demand for data storage capacity and the environmental sustainability of electronic storage devices ask for the use of innovative technologies. Extensive production of such devices encounters an economical barrier, where a low production cost is fundamental for a sustainable production chain. The use of graphene both as functionalizing and as passivating layer emerged as a solution matching the demands listed above. It shifted the interest of the scientific community in the past decade towards the optimization of graphene growth, using a variety of different approaches. In this thesis, a multi-technique characterization of single-layer graphene growth on top of ferromagnetic supports is reported. Preceding the graphene growth, characterization of the temperature-dependent thickness behavior of thin metallic films allowed for the optimization of their quality, followed by the investigation of the electronic properties of the metal films. The substrate was chosen as cobalt both from geometrical reasons, i.e. lattice mismatch, as well as better suitability to the experimental setup used. Using spatially resolved techniques, the well-known Co martensitic phase transition as a function of temperature has been observed and characterized. On top of the cobalt support, the chemical vapor deposition growth has been used for the formation of a graphene monolayer, using ethylene as the carbon supply. The graphene crystallographic quality varies as a function of growth temperature showing different azimuthal alignments with respect to the substrate. However, in this thesis, it is demonstrated that a transformation involving carbon exchange with the substrate allows reverting the different configurations in an epitaxially aligned graphene monolayer. The subsequent characterization of the electronic structure reveals that the single spin-polarized feature near the Fermi level, forming upon graphene adsorption on cobalt, is a general characteristic of the interface, independent on the relative orientation at the graphene-cobalt interface. Having control over the epitaxial relation between the graphene and the cobalt substrate, modification of graphene-substrate interaction can be achieved either by controlled substitutional implantation of exospecies into the C lattice mesh or by intercalation of foreign species. Therefore, in this thesis the nitrogen substitution within the graphene lattice as well as oxygen and gold intercalation at the graphene-Co interface have been studied. The momentum mapping unravels that the modification of the graphene-cobalt interaction leads to the disappearance of the single spin-polarized band in graphene.

Note: Universität Duisburg, Diss., 2020

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Contributing Institute(s):

1. Elektronische Eigenschaften (PGI-6)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

Appears in the scientific report 2020

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Database coverage:
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