Chemical vapor deposition of YBa2Cu3O7 using metalorganic chelate precursors

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 Tc 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.