Electronic and quantum transport properties of metallic and semiconducting nanowires

Simbeck, Adam J.
Thumbnail Image
Other Contributors
Nayak, Saroj K.
Giedt, Joel
Gall, Daniel
Wang, G.-C. (Gwo-Ching), 1946-
Issue Date
Terms of Use
This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.
Full Citation
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.
August 2014
School of Science
Dept. of Physics, Applied Physics, and Astronomy
Rensselaer Polytechnic Institute, Troy, NY
Rensselaer Theses and Dissertations Online Collection
Restricted to current Rensselaer faculty, staff and students. Access inquiries may be directed to the Rensselaer Libraries.