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

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dc.contributor.advisor Fagas, Gíorgos en
dc.contributor.author Sharma, Dimpy
dc.date.accessioned 2013-05-23T15:47:57Z
dc.date.available 2016-01-29T05:00:06Z
dc.date.issued 2013
dc.date.submitted 2013
dc.identifier.citation Sharma, 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.uri http://hdl.handle.net/10468/1136
dc.description.abstract This 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.sponsorship Science Foundation Ireland (06/IN.1/I857)
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2013, Dimpy Sharma. en
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/3.0/ en
dc.subject Silicon nanowires en
dc.subject.lcsh Nanowires en
dc.subject.lcsh Electronic structure en
dc.title Investigation of numerical atomic orbitals for first-principles calculations of the electronic and transport properties of silicon nanowire structures en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD (Science) en
dc.internal.availability Full text available en
dc.check.info Restricted to everyone for one year. en
dc.description.version Accepted Version
dc.contributor.funder Science Foundation Ireland en
dc.description.status Not peer reviewed en
dc.internal.school Chemistry en
dc.internal.school Tyndall National Institute en
dc.check.type No Embargo Required
dc.check.reason This thesis is due for publication or the author is actively seeking to publish this material. en
dc.check.opt-out Not applicable en
dc.thesis.opt-out false *
dc.check.embargoformat E-thesis only en
ucc.workflow.supervisor cora@ucc.ie *


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© 2013, Dimpy Sharma. Except where otherwise noted, this item's license is described as © 2013, Dimpy Sharma.
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