Investigation of numerical atomic orbitals for first-principles calculations of the electronic and transport properties of silicon nanowire structures

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dc.check.embargoformatE-thesis onlyen
dc.check.infoRestricted to everyone for one year.en
dc.check.opt-outNot applicableen
dc.check.reasonThis thesis is due for publication or the author is actively seeking to publish this material.en
dc.check.typeNo Embargo Required
dc.contributor.advisorFagas, Gíorgosen
dc.contributor.authorSharma, Dimpy
dc.contributor.funderScience Foundation Irelanden
dc.date.accessioned2013-05-23T15:47:57Z
dc.date.available2016-01-29T05:00:06Z
dc.date.issued2013
dc.date.submitted2013
dc.description.abstractThis thesis is focused on the application of numerical atomic basis sets in studies of the structural, electronic and transport properties of silicon nanowire structures from first-principles within the framework of Density Functional Theory. First we critically examine the applied methodology and then offer predictions regarding the transport properties and realisation of silicon nanowire devices. The performance of numerical atomic orbitals is benchmarked against calculations performed with plane waves basis sets. After establishing the convergence of total energy and electronic structure calculations with increasing basis size we have shown that their quality greatly improves with the optimisation of the contraction for a fixed basis size. The double zeta polarised basis offers a reasonable approximation to study structural and electronic properties and transferability exists between various nanowire structures. This is most important to reduce the computational cost. The impact of basis sets on transport properties in silicon nanowires with oxygen and dopant impurities have also been studied. It is found that whilst transmission features quantitatively converge with increasing contraction there is a weaker dependence on basis set for the mean free path; the double zeta polarised basis offers a good compromise whereas the single zeta basis set yields qualitatively reasonable results. Studying the transport properties of nanowire-based transistor setups with p+-n-p+ and p+-i-p+ doping profiles it is shown that charge self-consistency affects the I-V characteristics more significantly than the basis set choice. It is predicted that such ultrascaled (3 nm length) transistors would show degraded performance due to relatively high source-drain tunnelling currents. Finally, it is shown the hole mobility of Si nanowires nominally doped with boron decreases monotonically with decreasing width at fixed doping density and increasing dopant concentration. Significant mobility variations are identified which can explain experimental observations.en
dc.description.sponsorshipScience Foundation Ireland (06/IN.1/I857)
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationSharma, D. 2013. Investigation of numerical atomic orbitals for first-principles calculations of the electronic and transport properties of silicon nanowire structures. PhD Thesis, University College Cork.en
dc.identifier.urihttps://hdl.handle.net/10468/1136
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2013, Dimpy Sharma.en
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectSilicon nanowiresen
dc.subject.lcshNanowiresen
dc.subject.lcshElectronic structureen
dc.thesis.opt-outfalse*
dc.titleInvestigation of numerical atomic orbitals for first-principles calculations of the electronic and transport properties of silicon nanowire structuresen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD (Science)en
ucc.workflow.supervisorcora@ucc.ie*
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