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Electronic properties of graphene from tight-binding simulations

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Harju, Ari, Adjunct Prof., Aalto University, Department of Applied Physics, Finland
dc.contributor.author Uppstu, Andreas
dc.date.accessioned 2014-08-23T09:00:12Z
dc.date.available 2014-08-23T09:00:12Z
dc.date.issued 2014
dc.identifier.isbn 978-952-60-5815-3 (electronic)
dc.identifier.isbn 978-952-60-5814-6 (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/123456789/13833
dc.description.abstract Graphene is an effectively two-dimensional semimetallic material consisting of a sheet of carbon atoms arranged in a hexagonal lattice. Due to its high electron mobility and special electronic properties, it is considered to be a promising candidate for various future electronic applications. Freestanding graphene was discovered as late as in 2004, but since then it has become the focus of numerous studies, sparking not only scientific but also significant commercial interest. Realizing the potential of the material requires both theoretical, numerical, and experimental studies. An important computational model for studying the electronic properties of graphene is the so-called tight-binding (TB) model. In the TB model, the charge carriers of a material are described using effective parameters, which can be either derived from more complex models or fitted to experimental or computational results. In this Thesis, the TB model was used to study both the local density of states (LDOS) of graphene as well as electronic transport in graphene. Simulating the LDOS of graphene is important, since it may be more or less directly measured using scanning tunneling microscopy (STM), and is thus extremely helpful for characterizing the properties of nanometer-sized graphene samples. The results presented in this Thesis, which show good agreement between simulations and STM measurements, help to determine the electronic structure of graphene quantum dots on various substrates. Simulations of electronic transport aid in making graphene useful for semiconductor applications. Graphene may be turned semiconducting by various means, such as by cutting it into ribbons or by adding disorder. In this Thesis, it was showed how scaling theory can be utilized to obtain the conductance of a mesoscopically sized disordered graphene device using first-principles-based results and how the localization length of the charge carriers can be obtained effectively using the so-called Kubo-Greenwood method. The results aid in interpreting experimental conductance measurements and in estimating how strong disorder is required to turn graphene into an effective semiconductor.  en
dc.description.abstract Grafen är ett effektivt tvådimensionellt material som består av kolatomer arrangerade i ett hexagonalt gitter. Tack vare speciella elektroniska egenskaper, som laddningsbärarnas höga mobilitet, anses grafen vara en lovande kandidat för framtida elektroniska tillämpningar. Fristående grafen upptäktes så sent som 2004, men sedan dess har materialet blivit fokus för otaliga studier. Förutom ett vetenskapligt intresse, har grafen under den senaste tiden också skapat ett betydande kommersiellt intresse. För att förverkliga materialets potential krävs både teoretiska, numeriska och experimentella studier. Den så kallade starkbindningsmodellen är en viktig numerisk modell för simulering av grafen. I starkbindningsmodellen beskrivs laddningsbärarna med hjälp av effektiva parametrar, som kan härledas med hjälp av mera komplexa numeriska metoder eller genom att anpassa dem till experimentella resultat. I denna avhandling används starkbindningsmodellen till att simulera både lokal tillståndstäthet samt elektronisk transport i grafen. Att simulera lokal tillståndstäthet är viktigt, eftersom den kan mer eller mindre direkt mätas genom sveptunnelmikroskopi. Därmed är metoden extremt användbar för att karakterisera nanometerstora grafenflagor. Resultaten som presenteras i denna avhandling visar att simuleringarna stämmer bra överens med experimentella resultat. Simuleringar av elektronisk transport kan hjälpa med att få grafen användbart för halvledarapplikationer. Grafen kan fås till att bli en halvledare med olika metoder, till exempel genom att skära den i strimlor eller lägga till oordning i det annars perfekta gittret. I denna avhandling visas hur man kan använda ab initio -baserade metoder för att beräkna grafens konduktans och hur den så kallade Kubo-Greenwood-metoden kan användas till att beräkna laddningsbärarnas lokaliseringslängd. Dessa resultat hjälper att tolka experimentella mätresultat och att estimera hur stark oordning krävs för att ändra grafen till en effektiv halvledare. sv
dc.format.extent 60 + app. 110
dc.format.mimetype application/pdf en
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 122/2014
dc.relation.haspart [Publication 1]: Y. Hancock, A. Uppstu, K. Saloriutta, A. Harju and M. J. Puska. Generalized tight-binding transport model for graphene nanoribbon-based systems. Physical Review B, 81, 245402, 2010. DOI: 10.1103/PhysRevB.81.245402.
dc.relation.haspart [Publication 2]: J. van der Lit, M. P. Boneschanscher, D. Vanmaekelbergh, M. Ijäs, A. Uppstu, M. Ervasti, A. Harju, P. Liljeroth and I. Swart. Suppression of electron-vibron coupling in graphene nanoribbons contacted via a single atom. Nature Communications, 4, 2023, 2013. DOI: 10.1038/ncomms3023.
dc.relation.haspart [Publication 3]: M. Ijäs, M. Ervasti, A. Uppstu, P. Liljeroth, J. van der Lit, I. Swart, and A. Harju. Electronic states in finite graphene nanoribbons: Effect of charging and defects. Physical Review B, 88, 075429, 2013. DOI: 10.1103/PhysRevB.88.075429.
dc.relation.haspart [Publication 4]: S. K. Hämäläinen, Z. Sun, M. P. Boneschanscher, A. Uppstu, M. Ijäs, A. Harju, D. Vanmaekelbergh, and Peter Liljeroth. Quantum-Confined Electronic States in Atomically Well-Defined Graphene Nanostructures. Physical Review Letters, 107, 236803, 2011. DOI: 10.1103/PhysRevLett.107.236803.
dc.relation.haspart [Publication 5]: R. Drost, A. Uppstu, F. Schulz, S. K. Hämäläinen, M. Ervasti, A. Harju, and P. Liljeroth. Electronic States at the Graphene - Hexagonal Boron Nitride Zigzag Interface. Accepted for publication in Nano Letters, July 2014. DOI: 10.1021/nl501895h.
dc.relation.haspart [Publication 6]: Z. Fan, A. Uppstu, T. Siro and A. Harju. Efficient linear-scaling quantum transport calculations on graphics processing units and applications on electron transport in graphene. Computer Physics Communications, 185, 28, 2014. DOI: 10.1016/j.cpc.2013.08.009.
dc.relation.haspart [Publication 7]: M. Oksanen, A. Uppstu, A. Laaksonen, D. J. Cox, M. F. Craciun, S. Russo, A. Harju and P. Hakonen. Single-mode and multimode Fabry-Perot interference in suspended graphene. Physical Review B, 89, 121414(R), 2013. DOI: 10.1103/PhysRevB.89.121414.
dc.relation.haspart [Publication 8]: A. Uppstu, Z. Fan and A. Harju. Obtaining localization properties efficiently using the Kubo-Greenwood formalism. Physical Review B, 89, 075420, 2014. DOI: 10.1103/PhysRevB.89.075420.
dc.relation.haspart [Publication 9]: A. Uppstu, K. Saloriutta, A. Harju, M. Puska and A.-P. Jauho. Electronic transport in graphene-based structures: An effective cross-section approach. Physical Review B, 85, 041401(R), 2012. DOI: 10.1103/PhysRevB.85.041401.
dc.relation.haspart [Publication 10]: K. Saloriutta, A. Uppstu, A. Harju and M. J. Puska. Ab initio transport fingerprints for resonant scattering in graphene. Physical Review B, 86, 235417, 2012. DOI: 10.1103/PhysRevB.86.235417.
dc.relation.haspart [Publication 11]: A. Uppstu and A. Harju. High-field magnetoresistance revealing scattering mechanisms in graphene. Physical Review B, 86, 201409(R), 2012. DOI: 10.1103/PhysRevB.86.201409.
dc.relation.haspart [Publication 12]: Y. Hancock, K. Saloriutta, A. Uppstu, A. Harju and M. J. Puska. Spin-Dependence in Asymmetric, V-Shaped-Notched Graphene Nanoribbons. Journal of Low Temperature Physics, 153, 393, 2008. DOI: 10.1007/s10909-008-9838-y.
dc.subject.other Physics en
dc.title Electronic properties of graphene from tight-binding simulations en
dc.title Grafens elektroniska egenskaper från starkbindningssimuleringar sv
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 tight-binding en
dc.subject.keyword electronic transport en
dc.subject.keyword scanning tunneling microscopy en
dc.subject.keyword grafen sv
dc.subject.keyword starkbindning sv
dc.subject.keyword elektronisk transport sv
dc.subject.keyword sveptunnelmikroskopi sv
dc.identifier.urn URN:ISBN:978-952-60-5815-3
dc.type.dcmitype text en
dc.type.ontasot Doctoral dissertation (article-based) en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.contributor.supervisor Nieminen, Risto, Aalto Distinguished Prof., Aalto University, Department of Applied Physics, Finland
dc.opn Yazyev, Oleg, Prof., École Polytechnique Fédérale de Lausanne, Switzerland
dc.date.dateaccepted 2014-06-18
dc.rev Kotakoski, Jani, Dr., University of Vienna, Austria
dc.rev Zozoulenko, Igor, Prof., Linköping University, Sweden
dc.date.defence 2014-09-12


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