Silicon Nanocrystals and Defect States in Silicon Rich Silicon Nitride for Optoelectronic Applications

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dc.contributor.advisorCogan, Stuart F.
dc.creatorMohammed, Shakil
dc.date.accessioned2017-01-24T16:37:30Z
dc.date.available2017-01-24T16:37:30Z
dc.date.created2016-12
dc.date.issued2016-12
dc.date.submittedDecember 2016
dc.date.updated2017-01-24T16:37:30Z
dc.description.abstractResearch interest in silicon nanocrystals (Si-NC) has increased significantly as a result of the desire to improve the light emission efficiency of bulk silicon. Si-NCs embedded in silicon nitride have desirable characteristics for optoelectronic applications since they can increase the tunneling probability and have a lower tunneling barrier than silicon oxide. Higher tunneling probability is an important feature as it can be used to develop more efficient electroluminescent and photovoltaic devices. In this dissertation, the Si-rich Si3N4 (SRN) was prepared using low pressure chemical vapor deposition (LPCVD) and RF sputtering followed by high temperature treatment in order to precipitate Si-NCs within the silicon nitride matrix. Several different characterization techniques were used on the Si-NC samples in order to understand the physical, structural, optical and electrical behavior of the nanocrystals. Characterization techniques used in this analysis included photoluminescence (PL), time resolved PL, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy, ellipsometry and capacitance-voltage (C-V) measurements. Silicon nitride was found to contain a high defect density which suppressed the PL effect from the Si-NC. The PL observed from each different SRN sample correlated to defect states, namely dangling bonds and oxygen related bonding. Although substantial evidence suggested that Si-NC had formed within the SRN sample, a PL effect due to the quantum confinement effect (QCE) from the nanocrystals could not be detected. However, Si rich SiOx samples exhibited excellent PL which correlated with the QCE for an indirect bandgap semiconductor. Further experiments were conducted using forming gas in order to passivate the defects in the SRN. Though significant changes in PL was not achieved due to passivation, the electrical behavior from the SRN indicated that the intrinsically charged defects may have been passivated.
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/10735.1/5226
dc.language.isoen
dc.rightsCopyright ©2016 is held by the author. Digital access to this material is made possible by the Eugene McDermott Library. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
dc.subjectSilicon
dc.subjectSilicon nitride
dc.subjectQuantum dots
dc.subjectNanocrystals
dc.subjectSilicon carbide
dc.subjectOxidation
dc.subjectDefect states
dc.subjectStress
dc.titleSilicon Nanocrystals and Defect States in Silicon Rich Silicon Nitride for Optoelectronic Applications
dc.typeDissertation
dc.type.materialtext
thesis.degree.departmentMaterials Science and Engineering
thesis.degree.grantorUniversity of Texas at Dallas
thesis.degree.levelDoctoral
thesis.degree.namePHD

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