Annealing Conditions of Bi2Sr2CaCu2O8+x/CeO2/r-plane Sapphire by MOD Method

We have been studying Bi2Sr2CaCu2O8+x (Bi-2212) thin films on CeO2 buffered r-plane sapphire substrates by a metal organic decomposition (MOD) method. The deposited Bi-2212 thin films showed the c-axis oriented, and the in-plane orientation of the films showed 4-fold symmetry. However, we had a problem that Bi-2212 thin films were dissipation by thermal decomposition when the thin films were annealed above 840 °C in air atmosphere. In this study, we investigate the annealing conditions of Bi- 2212 thin films. We found TC of Bi-2212 thin films were dependence on the annealing condition such as a gas atmosphere and annealing times. The TC of Bi-2212 thin film annealed at 840 °C for 60 min in nitrogen atmosphere was 68.5 K. On the other hand, in oxygen atmosphere, TC was 65 K at the same annealing condition.