Dilute nitride semiconductors : band structure, scattering and high field transport

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dc.contributor.advisor O'Reilly, Eoin P. en
dc.contributor.advisor Fahy, Stephen B. en
dc.contributor.author Seifikar, Masoud
dc.date.accessioned 2014-01-27T16:18:44Z
dc.date.available 2014-01-27T16:18:44Z
dc.date.issued 2013
dc.date.submitted 2013
dc.identifier.citation Seifikar, M. 2013. Dilute nitride semiconductors : band structure, scattering and high field transport. PhD Thesis, University College Cork. en
dc.identifier.endpage 179
dc.identifier.uri http://hdl.handle.net/10468/1338
dc.description.abstract The substitution of a small fraction x of nitrogen atoms, for the group V elements in conventional III-V semiconductors such as GaAs and GaSb strongly perturbs the conduction band of the host semiconductor. In this thesis we investigate the effects of nitrogen states on the band dispersion, carrier scattering and mobility of dilute nitride alloys. In the supercell model we solve the single particle Hamiltonian for a very large supercell containing randomly placed nitrogen. This model predicts a gap in the density of states of GaNxAs1−x, where this gap is filled in the Green’s function model. Therefore we develop a self-consistent Green’s function (SCGF) approach, which provides excellent agreement with supercell calculations and reveals a gap in the DOS, in contrast with the results of previous non-self-consistent Green’s function calculations. However, including the distribution of N states destroys this gap, as seen in experiment. We then examine the high field transport of carriers by solving the steadystate Boltzmann transport equation and find that it is necessary to include the full distribution of N levels in order to account for the small, low-field mobility and the absence of a negative differential velocity regime observed experimentally with increasing x. Overall the results account well for a wide range of experimental data. We also investigate the band structure, scattering and mobility of carriers by finding the poles of the SCGF, which gives lower carrier mobility for GaNxAs1−x, compared to those already calculated, in better agreement with experiments. The calculated optical absorption spectra for InyGa1−yNxAs1−x and GaNxSb1−x using the SCGF agree well with the experimental data, confirming the validity of this approach to study the band structure of these materials. en
dc.description.sponsorship Science Foundation Ireland (06/IN.1/I90); Science Foundation Ireland (10/IN.1/I2994) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights ©2013, Masoud Seifikar. en
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/3.0/ en
dc.subject GaNAs en
dc.subject GaNSb en
dc.subject Band structure en
dc.subject Electronic structure en
dc.subject Dilute nitride alloys en
dc.subject Density of states en
dc.subject Green's function en
dc.subject Optical properties en
dc.subject High field transport en
dc.subject Boltzmann transport equation en
dc.subject Optical absorption en
dc.subject Conduction band structure en
dc.subject.lcsh Semiconductors en
dc.title Dilute nitride semiconductors : band structure, scattering and high field transport 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 No embargo required en
dc.description.version Accepted Version
dc.contributor.funder Science Foundation Ireland en
dc.description.status Not peer reviewed en
dc.internal.school Physics 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 true
dc.check.embargoformat Not applicable en
ucc.workflow.supervisor eoin.oreilly@tyndall.ie
dc.internal.conferring Autumn Conferring 2013 en

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