Computational modeling of defects in nanoscale device materials

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dc.check.embargoformatNot applicableen
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dc.contributor.advisorGreer, James C.en
dc.contributor.authorGreene-Diniz, Gabriel
dc.contributor.funderIrish Research Council for Science, Engineering and Technologyen
dc.date.accessioned2015-11-09T13:05:30Z
dc.date.available2015-11-09T13:05:30Z
dc.date.issued2014
dc.date.submitted2014
dc.description.abstractThis PhD thesis concerns the computational modeling of the electronic and atomic structure of point defects in technologically relevant materials. Identifying the atomistic origin of defects observed in the electrical characteristics of electronic devices has been a long-term goal of first-principles methods. First principles simulations are performed in this thesis, consisting of density functional theory (DFT) supplemented with many body perturbation theory (MBPT) methods, of native defects in bulk and slab models of In0.53Ga0.47As. The latter consist of (100) - oriented surfaces passivated with A12O3. Our results indicate that the experimentally extracted midgap interface state density (Dit) peaks are not the result of defects directly at the semiconductor/oxide interface, but originate from defects in a more bulk-like chemical environment. This conclusion is reached by considering the energy of charge transition levels for defects at the interface as a function of distance from the oxide. Our work provides insight into the types of defects responsible for the observed departure from ideal electrical behaviour in III-V metal-oxidesemiconductor (MOS) capacitors. In addition, the formation energetics and electron scattering properties of point defects in carbon nanotubes (CNTs) are studied using DFT in conjunction with Green’s function based techniques. The latter are applied to evaluate the low-temperature, low-bias Landauer conductance spectrum from which mesoscopic transport properties such as the elastic mean free path and localization length of technologically relevant CNT sizes can be estimated from computationally tractable CNT models. Our calculations show that at CNT diameters pertinent to interconnect applications, the 555777 divacancy defect results in increased scattering and hence higher electrical resistance for electron transport near the Fermi level.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationGreene-Diniz, G. F. 2014. Computational modeling of defects in nanoscale device materials. PhD Thesis, University College Cork.en
dc.identifier.endpage163
dc.identifier.urihttps://hdl.handle.net/10468/2046
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2014, Gabriel F. Greene-Diniz.en
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectPhysicsen
dc.subjectMicroelectronicsen
dc.subjectNanoelectronicsen
dc.subjectAb-initioen
dc.subjectInterfacesen
dc.subjectIII-Ven
dc.subjectFirst principlesen
dc.subjectDensity functional theoryen
dc.subjectGreen's functionsen
dc.subjectPoint defectsen
dc.subjectElectron transporten
dc.subjectMany body perturbation theoryen
dc.subjectCarbon nanotubesen
dc.thesis.opt-outfalse
dc.titleComputational modeling of defects in nanoscale device materialsen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePHD (Engineering)en
ucc.workflow.supervisorjim.greer@tyndall.ie
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