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Author:Uppstu, Andreas
Title:Electronic and transport properties of graphene nanoribbons with applications for device design
Grafenstrimlors elektroniska egenskaper samt modellering av grafenbaserade komponenter
Publication type:Master's thesis
Publication year:2010
Pages:46      Language:   eng
Department/School:Informaatio- ja luonnontieteiden tiedekunta
Main subject:Fysiikka (laskennallinen fysiikka)   (Tfy-105)
Supervisor:Nieminen, Risto
Instructor:Harju, Ari
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
Instructions

Reading digital theses in the closed network of the Aalto University Harald Herlin Learning Centre

In the closed network of Learning Centre you can read digital and digitized theses not available in the open network.

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Location:P1 Ark Aalto  36   | Archive
Keywords:graphene
tight-binding
Hubbard model
electron transport
grafen
tight-binding-modell
Hubbard-modell
elektrontransport
Abstract (eng): Graphene is an allotrope of carbon consisting of a single sheet of atoms arranged in a hexagonal lattice, and graphene nanoribbons are quasi-one dimensional graphene strips of nanometer width.
In this thesis, generalized tight-binding methods for modelling the electronic structure and the transport properties of graphene nanoribbons are studied and compared to computationally heavier ab initio methods.

The tight-binding model is a commonly used method to compute the electronic properties of carbon-based materials.
The method relies on the assumption that the electrons are tightly bound to the lattice sites, and the energy cost for an electron to jump to a neighboring lattice site is taken as a free parameter.
The model is extended by introducing further than nearest neighbor hopping, and a mean field Hubbard term that models the on-site Coulombic repulsion.
The extended model presented in this thesis is then used to compute the electronic transport properties of notched graphene nanoribbons with zigzag edges, which may possibly be used as spin-injection devices or spin filters.
Abstract (swe): Grafen är en allotrop av kol som består av ett enda lager kolatomer ordnade i ett hexagonalt gitter, och grafenstrimlor är nanometertunna kvasi-endimensionella strimlor av grafen.
I detta arbete undersöks generaliserade tight-bindingmetoder för modellering av elektroner och elektrontrasport i grafenstrimlor, och resultaten jämförs med tyngre metoder som baserar sig på första principer.

Tight-binding-metoden är en väletablerad modell som ofta har använts till att modellera kolbaserade material.
Metoden förutsätter att elektronerna är starkt bundna till gitterpunkterna, och energikostnaden för att en elektron skall hoppa till en grannpunkt är tagen som en fri parameter.
Metoden kan generaliseras genom att inkludera hoppning till mera avlägsna gitterpunkter, samt genom att modellera elektronernas repulsion med en Hubbard-term.
Den generaliserade metoden som presenteras i detta arbete används sedan till att modellera elektrontransport i skårade grafenstrimlor med sicksackformade kanter, vilka kan möjligtvis anvndas som spinnfilter.
ED:2010-11-19
INSSI record number: 41337
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