Chemical vapor deposition of YBa2Cu3O7 using metalorganic chelate precursors

Abstract

Superconducting films of YBa₂ Cu₃ O₇ were prepared using metalorganic chelate precursors at ambient pressure. Ba and Y were transported using fluoride‐substituted β‐diketonates, while a β‐keto‐imide chelate was used for Cu. Deposition at 500 °C on Al₂ O₃ and SrTiO₃ substrates by reaction with O₂ saturated with room temperature water vapor formed crystalline mixtures of BaF₂ , YF₃ , and CuO. Superconducting YBa₂ Cu₃ O₇ formed after annealing in Ar/H₂O at 835 °C followed by O₂ at 900 and 400 °C with a slow cooling in O₂ to below 200 °C. A 2.3 μm film on a (100) SrTiO₃ substrate had an onset T_c of 90 K with zero resistance at 70 K. The film showed a mixture of c‐ and a‐axis orientation. A similar film on (11̄02) Al₂O₃ showed zero resistance at 65 K.