Effect of the post-deposition processing ambient on the preparation of superconducting YBa2Cu3O7−<i>x</i> coevaporated thin films using a BaF2 source

Abstract

We have investigated the effect of the post-deposition processing ambient on the preparation of YBa2Cu3O7−x thin films from a BaF2 source. The role of H2O vapor during the high-temperature anneal is understood through a thermodynamic analysis of the fluorine removal reaction. The role of a HF getter (e.g., SiO2) is understood through the same type of analysis. We have demonstrated that a zero resistance transition temperature at 77 K can be obtained for an annealing temperature as low as 690 °C for films deposited on SrTiO3 substrates by increasing the PH2O and decreasing PHF during the high-temperature soak cycle.