Polytype Stability, Microstructural Evolution, and Impurities at the Interface of Homoepitaxial 4H-SiC(1120) Thin Films Grown via Hot-Wall Chemical Vapor Deposition.

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dc.contributor.advisor Dr. Robert F. Davis, Committee Chair en_US
dc.contributor.advisor Dr. Lew Reynolds, Committee Member en_US
dc.contributor.advisor Dr. Raoul Schlesser, Committee Member en_US
dc.contributor.advisor Dr. John Muth, Committee Member en_US
dc.contributor.advisor Dr. Nadia El-Masry, Committee Member en_US
dc.contributor.author Bishop, Seann en_US
dc.date.accessioned 2010-04-02T18:55:40Z
dc.date.available 2010-04-02T18:55:40Z
dc.date.issued 2007-06-04 en_US
dc.identifier.other etd-01032007-165103 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/4533
dc.description.abstract The electronic properties of 4H-SiC make it a leading semiconductor material for high-power applications. Despite advances in SiC crystal growth, devices fabricated in 4H-SiC(0001) continue to be limited by defects like micropipes, dislocations and stacking faults. Investigations performed here on non-basal 4H-SiC have demonstrated micropipe-free, a-plane 4H-SiC films comparable with conventional 4H-SiC(0001). Improved device performance has been achieved for p-i-n rectifiers fabricated in a-plane 4H-SiC. Hot-wall chemical vapor deposition (CVD) is the most widely used growth process employed to meet the material demands for 4H-SiC-based high-power electronics; however, the suitability of this technique for the growth of thin films (<10 μm) is not well established. A detailed analysis of the epitaxial growth of a-plane 4H-SiC thin films by vertical, hot-wall CVD has been performed in this work. Two growth regimes were identified and termed sublimation growth and precursor growth. In the former, the SiC coating decomposes and results in the in-situ (sublimation) growth of epitaxial SiC films. It is proposed that in-situ layer aids in subsequent thin film growth from reactant gases. Transmission electron microscopy revealed areas without observable defects and an indistinguishable interface between the substrate and sublimation grown layer. Aluminum impurity concentrations to 3E18 per cc. were identified near the interface with the substrate. The influence of these impurities on the cathodoluminescence spectrum of 4H-SiC was studied. A model based on boundary layer theory was developed to explain the origin and the profile of the aluminum impurities. Secondary ion mass spectrometry revealed the SiC coating to be the major source of aluminum impurities. An argon diluent reduced the concentration of aluminum at the interface to 2E17 per cc. Films deposited via precursor growth exhibited specular surfaces. Optical and structural characterization showed the films replicate the polytype of the underlying substrate exactly. The microstructural evolution of a-plane 4H-SiC and III-nitride films was also investigated. 4H-SiC films showed evidence of step-flow growth in the sublimation-driven regime, while both step-flow and terrace nucleation and growth were observed in the precursor-driven regime. AlN initially grew via the Stranski-Krastanov mode on 4H-SiC , while the Volmer-Weber mode was observed for GaN on AlN. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject non-basal en_US
dc.subject AlN en_US
dc.subject GaN en_US
dc.subject aluminum contamination en_US
dc.subject hot wall chemical vapor deposition en_US
dc.subject III-Nitride en_US
dc.subject epitaxial growth en_US
dc.subject 4H-SiC en_US
dc.subject homoepitaxy en_US
dc.subject heteropolytypic en_US
dc.subject site competition en_US
dc.subject sublimation epitaxy en_US
dc.subject low temperature growth en_US
dc.subject vapor phase epitaxy en_US
dc.subject a-plane en_US
dc.subject CVD en_US
dc.subject (1120) en_US
dc.subject polytype replication en_US
dc.subject growth mode en_US
dc.subject microstructural evolution en_US
dc.subject lateral overgrowth en_US
dc.subject pendeo-epitaxy en_US
dc.title Polytype Stability, Microstructural Evolution, and Impurities at the Interface of Homoepitaxial 4H-SiC(1120) Thin Films Grown via Hot-Wall Chemical Vapor Deposition. en_US
dc.degree.name PhD en_US
dc.degree.level dissertation en_US
dc.degree.discipline Materials Science and Engineering en_US

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