Computational modeling of defects in nanoscale device materials

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dc.contributor.advisor Greer, James C. en
dc.contributor.author Greene-Diniz, Gabriel
dc.date.accessioned 2015-11-09T13:05:30Z
dc.date.available 2015-11-09T13:05:30Z
dc.date.issued 2014
dc.date.submitted 2014
dc.identifier.citation Greene-Diniz, G. F. 2014. Computational modeling of defects in nanoscale device materials. PhD Thesis, University College Cork. en
dc.identifier.endpage 163
dc.identifier.uri http://hdl.handle.net/10468/2046
dc.description.abstract This 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.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2014, Gabriel F. Greene-Diniz. en
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/3.0/ en
dc.subject Physics en
dc.subject Microelectronics en
dc.subject Nanoelectronics en
dc.subject Ab-initio en
dc.subject Interfaces en
dc.subject III-V en
dc.subject First principles en
dc.subject Density functional theory en
dc.subject Green's functions en
dc.subject Point defects en
dc.subject Electron transport en
dc.subject Many body perturbation theory en
dc.subject Carbon nanotubes en
dc.title Computational modeling of defects in nanoscale device materials en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PHD (Engineering) en
dc.internal.availability Full text available en
dc.check.info No embargo required en
dc.description.version Accepted Version
dc.contributor.funder Irish Research Council for Science, Engineering and Technology en
dc.description.status Not peer reviewed en
dc.internal.school Tyndall National Institute en
dc.check.type No Embargo Required
dc.check.reason No embargo required en
dc.check.opt-out Not applicable en
dc.thesis.opt-out false
dc.check.embargoformat Not applicable en
ucc.workflow.supervisor jim.greer@tyndall.ie
dc.internal.conferring Spring Conferring 2015


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© 2014, Gabriel F. Greene-Diniz. Except where otherwise noted, this item's license is described as © 2014, Gabriel F. Greene-Diniz.
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