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

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dc.contributor.advisorO'Reilly, Eoin P.en
dc.contributor.advisorFahy, Stephen B.en
dc.contributor.authorSeifikar, Masoud
dc.contributor.funderScience Foundation Irelanden
dc.date.accessioned2014-01-27T16:18:44Z
dc.date.available2014-01-27T16:18:44Z
dc.date.issued2013
dc.date.submitted2013
dc.description.abstractThe 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.sponsorshipScience Foundation Ireland (06/IN.1/I90); Science Foundation Ireland (10/IN.1/I2994)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationSeifikar, M. 2013. Dilute nitride semiconductors : band structure, scattering and high field transport. PhD Thesis, University College Cork.en
dc.identifier.endpage179
dc.identifier.urihttps://hdl.handle.net/10468/1338
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights©2013, Masoud Seifikar.en
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectGaNAsen
dc.subjectGaNSben
dc.subjectBand structureen
dc.subjectElectronic structureen
dc.subjectDilute nitride alloysen
dc.subjectDensity of statesen
dc.subjectGreen's functionen
dc.subjectOptical propertiesen
dc.subjectHigh field transporten
dc.subjectBoltzmann transport equationen
dc.subjectOptical absorptionen
dc.subjectConduction band structureen
dc.subject.lcshSemiconductorsen
dc.thesis.opt-outtrue
dc.titleDilute nitride semiconductors : band structure, scattering and high field transporten
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD (Science)en
ucc.workflow.supervisoreoin.oreilly@tyndall.ie
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