Quantum transport and bulk calculations for graphene-based devices

dc.contributor.advisorBanerjee, Sanjayen
dc.contributor.advisorRegister, Leonard F.en
dc.contributor.committeeMemberTutuc, Emanuelen
dc.contributor.committeeMemberMacDonald, Allan H.en
dc.contributor.committeeMemberLee, Jacken
dc.contributor.committeeMemberGanguly, Swaroopen
dc.creatorBasu, Dipanjanen
dc.date.accessioned2011-02-02T17:27:27Zen
dc.date.available2011-02-02T17:27:27Zen
dc.date.available2011-02-02T17:27:48Zen
dc.date.issued2010-12en
dc.date.submittedDecember 2010en
dc.date.updated2011-02-02T17:27:48Zen
dc.descriptiontexten
dc.description.abstractAs devise sizes approach the nanoscale, novel device geometries and materials are considered, and new types of essential physics becomes important and new physical switching mechanism are considered, and as our intuitive understanding of device behavior is stretched accordingly, increasing first-principles simulation is required to understand and predict device behavior. To this end, initially I worked to capture the richness of the confinement and transport physics in quantum-wire devices. I developed an efficient fully three dimensional atomistic quantum transport simulator within a nearest-neighbor atomistic tight-binding framework. However, I soon adapted this work to the study of transport in graphene mono-layer and bilayer nano-ribbons. Motivated by proposals for use of nano-ribbons to create band gaps in otherwise gapless graphene monolayers, I studied the effects of edge disorder in such graphene nano-ribbon FETs. I found that ribbon widths sufficiently narrow to produce useful bandgaps, would also lead to an extreme sensitivity to ribbon-edge roughness and associated performance degradation and device-to-device variability. Going beyond conventional switching but staying with the graphene material system, to model electron-hole condensation in two graphene monolayers separated by a tunnel dielectric potentially beyond room temperature, I developed a self-consistent atomistic tight-binding treatment of the required interlayer exchange interaction within non-local Hartree-Fock mean-field theory. Such condensation, associated many-body enhanced interlayer current flow, and gate-control thereof is the basis for the beyond-CMOS Bilayer-pseudoSpin Field Effect Transistor (BiSFET) proposed by colleagues. I studied the effect of various system parameters and on interlayer charge imbalance on the strength of the condensate state. I also modeled the critical current, the maximum interlayer current that can be supported by the condensate, its detailed dependence on the nature and strength of the required interlayer bare tunneling and on charge imbalance. The results presented here are expected to be used to refine devices models of the BiSFET, and may serve as guides to experiments to observe such a condensate state.en
dc.description.departmentElectrical and Computer Engineeringen
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttp://hdl.handle.net/2152/ETD-UT-2010-12-2081en
dc.language.isoengen
dc.subjectGrapheneen
dc.subjectTight-bindingen
dc.subjectQuantum transporten
dc.subjectMOSFETsen
dc.titleQuantum transport and bulk calculations for graphene-based devicesen
dc.type.genrethesisen
thesis.degree.departmentElectrical and Computer Engineeringen
thesis.degree.disciplineElectrical & Computer Engrng (Solid-State Electronics)en
thesis.degree.grantorUniversity of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen
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