In the eight years since its discovery, numerous materials have been identified as being compatible with YBa2Cu3O7-δ (YBCO). Investigation of potentially compatible compounds requires a knowledge of both the chemistry and microstructure of the interface between the superconductor and the material. In this work, spectroscopic ellipsometry (SE) is being developed as a rapid and non-destructive characterization tool for investigating these interfaces. In addition, SE was used to determine reference optical data for common YBCO substrate materials. These include BaZrO3, 9.5 mol% Y2O3-ZrO2 (YSZ), NdGaO3 and LaSrGaO4.
SE measurements of epitaxial YBCO on YSZ substrates have shown that it is possible to identify the formation of the known BaZrO3 reaction layer. The modeled thickness of the reaction layer, as well as the modeled thickness of the YBCO film, are as expected. SE measurements as a function of temperature for YBCO/SrTiO3 have also been obtained. The SE data shows dramatic changes from room temperature to high temperature. This is due to the strong dependence of the dielectric function of YBCO on the oxygen content of the film.