Electronic and transport properties of graphene nanoribbons with applications for device design
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School of Science |
Master's thesis
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Date
2010
Major/Subject
Fysiikka (laskennallinen fysiikka)
Mcode
Tfy-105
Degree programme
Language
en
Pages
46
Series
Abstract
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.Description
Supervisor
Nieminen, RistoThesis advisor
Harju, AriKeywords
graphene, grafen, tight-binding, tight-binding-modell, Hubbard model, Hubbard-modell, electron transport, elektrontransport