Passivation of superconducting YBa₂Cu₃O_7-x thin films by a wet fluoride vapor method

Wet hydrofluoric acid (HF) vapor was used to treat YBa₂Cu ₃O_7-x superconducting thin films in order to realize highly controllable passivation layers on the film surface. Improved resistance to degradation by water of the films was realized by using this novel technique. In situ measurement of the resistance of the thin films, with and without wet HF vapor treatment, showed completely different behavior during deionized water immersion. Both Auger electron spectroscopy surface scanning and depth profile demonstrated the incorporation of fluorine in the surface after wet HF vapor treatment. The formation of an amorphous layer on the film surface, which was the reaction product between HF and erosion materials on the film surface, might be directly related to the improved water resistance of the superconducting YBa₂Cu₃O_7-x thin films.