Reflection-transmission photoellipsometry: theory and experiments.

We propose a method that uses reflection and transmission photoellipsometry to analyze samples consisting of thin films combined with semitransparent thick layers or substrates in the form of multilayer structures. Athick film or substrate is defined as a layer for which no interference effects can be observed for a given wavelength resolution, and contributions from multiple reflections in the substrate are taken into account in the theoretical treatment. An automatic reflection-transmission spectroscopic ellipsometer was built to test the theory, and satisfactory results have been obtained. Examples corresponding to a strongly absorbing film deposited on a glass substrate and a highly transmitting film also deposited on glass are shown. In both cases a good fit between theory and experiment is found. The photoellipsometric method presented is particularly suited to the analysis of actual samples of energy-efficient coatings for windows.

Optical properties of granular tin films from 0.22 to 1.0 microm.

The optical properties of granular tin films were investigated in the spectral region from 0.22 to 1.0 microm. As the particles forming the films increased in size (from ~43.0 to 70.0 nm) the peak observed in the reflectance was shifted to longer wavelengths. Parameters such as the film thickness and the filling factor have been determined and served for the calculation of reflectance using the well-known Maxwell-Garnett approach. An extension of this theory was also used to characterize the granular films. The revised dipole theory that includes frequency-dependent terms neglected in the static approximation seems to give a better description of the optical behavior of granular surfaces.

Interband transitions in aggregated copper films.

The optical properties of aggregated copper films have been studied in the spectral range from 200 to 1000 nm. Although it is well known that these films exhibit an anomalous absorption in the visible region attributed by many authors to collective oscillations of electrons in the particles forming the films, not much interest has been shown in the study of interband transitions occurring in these aggregated films. The results of the present work indicate that interband transitions are also found in copper in aggregated form, and that their effects cannot be ignored in the analysis of the optical properties of island films.