Synthesis and electronic Properties of atomically well-defined Graphene Nanostructures

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Drost, Robert
dc.date.accessioned 2017-02-16T10:00:28Z
dc.date.available 2017-02-16T10:00:28Z
dc.date.issued 2016
dc.identifier.isbn 978-952-60-6707-0 (electronic)
dc.identifier.isbn 978-952-60-6706-3 (printed)
dc.identifier.issn 1799-4942 (electronic)
dc.identifier.issn 1799-4934 (printed)
dc.identifier.issn 1799-4934 (ISSN-L)
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/24599
dc.description.abstract The carbon allotrope graphene is the first member of a new family of two-dimensional materials which have roused the interest of scientists worldwide. Comprised of only a single layer of carbon atoms arranged on a honeycomb lattice, graphene has a peculiar electronic structure with linearly dispersing bands forming two Dirac cones at the Fermi level. These give rise to several unusual quantum effects such as Klein tunnelling and the integer quantum Hall effect as well as a high electron mobility through suppressed back scattering of charge carriers. Graphene has therefor been heralded as a replacement material for silicon in a new generation of low-power electronic devices. In order to compete with silicon electronics however, the size of gates, leads, and channels in graphene devices must be brought down into the nanometer range. At these length scales, the boundaries of the graphene structures will have a great influence on their properties and performance as a large fraction of atoms occupy edge sites. This thesis is concerned with the experimental realisation of atomically well-defined graphene systems and the study of their electronic properties by scanning tunnelling microscopy. The electronic properties of graphene are first introduced by means of a tight binding model, focusing on graphene nanoribbons as model systems. It is shown that both the size of the system and the symmetry of its edge have a significant influence on the electronic properties of small graphene structures. After these considerations, some approaches to realise well-defined graphene nanosystems are discussed and data on their electronic properties is presented. The major part of the experimental section is concerned with the zig-zag boundary of graphene and the resulting edge state, which is predicted to enable spintronics and valleytronics in all carbon nanostructures. Two attempts to produce stable zig-zag edges of high quality through self-assembly by chemical vapour deposition driven epitaxy of graphene and hexagonal boron nitride on an Ir(111) and Ni(111) surface are discussed. Atomically precise interfaces of over 150 nm length could be obtained, but no signature of the edge state is found on the as-grown samples. A further experiment is presented where the intercalation of gold under a sample grown on Ir(111) was used to decouple the heterostructures from their support and the edge state could be observed. Finally, data on narrow armchair graphene nanoribbons is presented. Numerical methods predict a nearly vanishing band gap for the structure considered here and they have hence been proposed as connections in graphene devices. The ribbons are self-assembled form molecular precursors by an Ullmann type reaction in vacuo on an Au(111) surface. Their electronic structure is examined by means of scanning tunnelling spectroscopy and a band gap of 0.1 eV could be extrapolated for ribbons of over ca. 6 nm length. en
dc.format.extent 117 + app. 39
dc.language.iso en en
dc.publisher Aalto University en
dc.publisher Aalto-yliopisto fi
dc.relation.ispartofseries Aalto University publication series DOCTORAL DISSERTATIONS en
dc.relation.ispartofseries 48/2016
dc.relation.haspart [Publication 1]: Fabian Schulz, Robert Drost, Sampsa K. Hämäläinen, Thomas Demonchaux, Ari P. Seitsonen, and Peter Liljeroth. Epitaxial Hexagonal Boron Nitride on Ir(111): A Work Function Template. Physical Review B, Volume 89, pp. 235429-1 - 235429-8, June 2014. DOI: 10.1103/PhysRevB.89.235429
dc.relation.haspart [Publication 2]: Robert Drost, Shawulienu Kezilebieke, Mikko M. Ervasti, Sampsa K. Hämäläinen, Fabian Schulz, Ari Harju, and Peter Liljeroth. Synthesis of Extended Atomically Perfect Zigzag Graphene - Boron Nitride Interfaces. Scientific Reports, Volume 5, Article No. 16741, October 2015. DOI: 10.1038/srep16741
dc.relation.haspart [Publication 3]: Robert Drost, Andreas Uppstu, Fabian Schulz, Sampsa K. Hämäläinen, Mikko Ervasti, Ari Harju, and Peter Liljeroth. Electronic States at the Graphene-Hexagonal Boron Nitride Zigzag Interface. Nano Letters, Volume 14, pp. 5128 - 5132, July 2014. DOI: 10.1021/nl501895h
dc.relation.haspart [Publication 4]: Amina Kimouche, Mikko Ervasti, Robert Drost, Simo Halonen, Ari Harju, Pekka Joensuu, Jani Sainio, and Peter Liljeroth. Ultra-Narrow Metallic Armchair Graphene Nanoribbons. Nature Communications, Volume 6, Article No. 10177, November 2015. DOI: 10.1038/ncomms10177
dc.subject.other Physics en
dc.title Synthesis and electronic Properties of atomically well-defined Graphene Nanostructures en
dc.type G5 Artikkeliväitöskirja fi
dc.contributor.school Perustieteiden korkeakoulu fi
dc.contributor.school School of Science en
dc.contributor.department Teknillisen fysiikan laitos fi
dc.contributor.department Department of Applied Physics en
dc.subject.keyword graphene en
dc.subject.keyword nanostructures en
dc.subject.keyword electronic properties en
dc.subject.keyword Iridium-111 en
dc.subject.keyword Ir(111) en
dc.subject.keyword Nickel-111 en
dc.subject.keyword Ni(111) en
dc.subject.keyword zig-zag edges en
dc.subject.keyword nanoribbons en
dc.subject.keyword heterostructures en
dc.subject.keyword epitaxial en
dc.subject.keyword boron nitride en
dc.identifier.urn URN:ISBN:978-952-60-6707-0
dc.type.dcmitype text en
dc.type.ontasot Doctoral dissertation (article-based) en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.contributor.supervisor Liljeroth, Peter, Prof., Aalto University, Department of Applied Physics, Finland
dc.opn Fasel, Roman, Prof., Eidgenössische Material Prüfungs- und Forschungsanstalt, Switzerland
dc.contributor.lab Atomic Scale Physics en
dc.rev Sutter, Peter, Prof., University of Nebraska-Lincoln, USA
dc.rev Auwärter, Wilhelm, Prof., Technische Universität München, Germany
dc.date.defence 2016-04-15


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