The development of new optoelectronic devices using group-III-nitride-heterostructures requires characterization techniques which give spatially resolved information about the local physical and chemical material properties. The goal of this work was the improvement of analytical STEM-techniques and its application on nano-characterization of III-N-heterostructures. The optimization of electron energy-loss spectroscopy provides a measurement techniques which yields spatially resolved information about bandgap energy and dielectric function on a nanometer scale. A combination of STEM-techniques like EELS, convergent electron diffcration (CBED) and Z-contrast imaging was used to characterize and improve structural properties, interfaces and chemical composition of InGaN-layers. The influence of growth parameters on the enhancement of interface sharpness was demonstrated. Additionally nanoscale fluctuations of the In-content could be proved by Z-contrast imaging and quantified by EELS. It was shown how v-defects in InGaN/GaN-superlattices can be eliminated by modulating the growth temperature during epitaxial growth. The improved EELS-techniques were used for measuring optical properties within III-N-heterostructures. The significance of the results could be demonstrated by a comparison to synchrotron measurements and bandstructure calculations. Due to the high spatial resolution optical properties of local separations and defects could be measured and correlated to chemical and structural properties.
| Identifer | oai:union.ndltd.org:DUETT/oai:DUETT:duett-09022002-092745 |
| Date | 02 September 2002 |
| Creators | Brockt, Georg |
| Contributors | Prof.em. Dr.-Ing. E.Kubalek, Prof. Dr. rer.nat. K. Heime, Aachen |
| Publisher | Gerhard-Mercator-Universitaet Duisburg |
| Source Sets | Dissertations and other Documents of the Gerhard-Mercator-University Duisburg |
| Language | German |
| Detected Language | English |
| Type | text |
| Format | text/html, application/pdf |
| Source | http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-09022002-092745/ |
| Rights | unrestricted, 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, dissertation, 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. Hiermit erteile ich der Universitaet Duisburg das nicht-ausschliessliche Recht unter den unten angegebenen Bedingungen, meine Dissertation, Staatsexamens- oder Diplomarbeit, meinen Forschungs- oder Projektbericht zu veroeffentlichen und zu archivieren. Ich behalte das Urheberrecht und das Recht das Dokument zu veroeffentlichen und in anderen Arbeiten weiterzuverwenden. |
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