Electronic and quantum transport properties of metallic and semiconducting nanowires
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Authors
Simbeck, Adam J.
Issue Date
2014-08
Type
Electronic thesis
Thesis
Thesis
Language
ENG
Keywords
Physics
Alternative Title
Abstract
Since graphene nanoribbons with pristine edges are experimentally challenging to fabricate, the role of defects is also considered here. Using first-principles density functional theory methods, the role of a two atom edge vacancy, or dent defect, in altering the electronic structure of oxygen-functionalized armchair graphene nanoribbons is investigated. Edge reconstruction in the vicinity of the defect causes the band gaps of the oxygen passivated graphene nanoribbons to decrease linearly with increasing defect density, and a defect, or midgap, state appears in the band gap region just above the Fermi energy. At experimental defect concentrations, finite gaps remain open but are reduced by roughly 15% compared to pristine structures. On the contrary, similarly defected hydrogenated systems undergo minor edge reconstruction such that only the nanoribbon width N is reduced from N to N - 1 in the vicinity of the twin vacancy. Here, the gap is predicted to remain open and follow a simple weighted average of the band gaps of the N and N - 1 ribbons as a function of defect concentration. Surprisingly, this electronic structure mixing model also applies to the band gap trend as a function of defect concentration for oxygenated ribbons.
Description
August 2014
School of Science
School of Science
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY