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| Hauptseite > Publikationsdatenbank > Development of Ellipsometric Microscopy as a Quantitative High-Resolution Technique for the Investigation of Thin Films at Glass-Water and Silicon-Air Interfaces |
| Hauptseite > Publikationsdatenbank > Development of Ellipsometric Microscopy as a Quantitative High-Resolution Technique for the Investigation of Thin Films at Glass-Water and Silicon-Air Interfaces |
| Dissertation / PhD Thesis/Book | PreJuSER-41884 |
2004
Forschungszentrum Jülich Gmbh Zentralbibliothek, Verlag
Jülich
ISBN: 3-89336-373-4
Please use a persistent id in citations: http://hdl.handle.net/2128/275
Abstract: The presented work deals with ellipsometric microscopy, an optical technique for the investigation of thin films. Ellipsometric microscopy combines two powerful optical techniques, microscopy and ellipsometry. The latter technique exploits the fact that the state of polarization of light changes in a well known way upon reflection at interfaces covered by thin films. Ellipsometry is a very accurate technique for simultaneously measuring thin film thickness and refractive index or extinction coefficient. Its main drawback is poor lateral resolution which is overcome in ellipsometric microscopy. The basic idea of ellipsometric microscopy had been proposed before and its feasibility was shown. The aims of this thesis were twofold. On the one hand, ellipsometric microscopy was to be converted from a qualitative technique into a reliable and quantitative method. On the other hand, the technique had to be improved to a point were the glass-water interface could be investigated for biophysical questions. These goals proved to be very demanding because interpreting ellipsometric data requires an exact control over the angle of incidence and the polarization of light. However, in microscopy it is necessary to use cones of light with opening angles as large as possible. Finding the best balance between these conflicting demands and interpreting the ellipsometric data accurately required careful theoretical analysis and very substantial improvements of the setup. The former setup was converted into a fully-fledged ellipsometric device. All optical and optoelectronic parts and most opto-mechanical parts of the setup were changed and optimized for the specific demands of the technique. Moreover, approaches for accurate alignment and calibration known from ellipsometry were adapted to ellipsometric microscopy. Zone averaging was implemented for systematic cancellation of remaining experimental uncertainties to first order. In order to enable quantitative experiments it was important to analyze and correct imperfections of the utilized CCD camera. However, the most important issue was to correct for the influence of the imaging optics on the ellipsometric data. This was solved by describing the optical components as part of the sample, i.e. they were modeled to contribute their own ellipsometric angles $\Delta$ and $\Psi$. The validity of this model and the performance of the improved setup were verified experimentally in the full domain of the ellipsometric angles $\Psi \in$ [0$^{\circ}$,90$^{\circ}$[ and $\Delta \in$ [0$^{\circ}$,360$^{\circ}$[ by systematic measurements on calibrated objects . These were silicon substrates coated with carefully controlled thin layers of MgF$_{2}$ and ZnS . To the best of my knowledge neither this nor any other approach for correcting the influence of the imaging optics on the ellipsometric data was described before. [...]
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