Interactions of YBa2Cu3O7−x thin films with alkaline earth fluoride substrates

Abstract

Film-substrate interactions of YBazC!u307-, (YBCO) thin films grown by pulsed laser deposition on alkaline earth fluoride substrates were investigated. X-ray photoelectron spectroscopy, atomic force microscopy, and x-ray-diffraction measurements showed that the quality of the film and amount of chemical reaction between film and substrate were dependent on the substrate material and deposition temperature. The reaction of YBCO films with CaF2 and MgFz substrates forms BaF, and calcium or magnesium oxide species. The reacted film is insulating and has a microscopically rough surface. No reaction was detected in films deposited on BaFz and SrF2. Physical and thermodynamic properties which may explain the observed order of reactivity are examined. 3194