Characteristics of MOD Bi-2212 Thin Films on r-Cut Sapphire With $\hbox {CeO}_{2}$ Buffer Layer

We have studied Bi₂Sr₂CaCu₂O_8+δ (Bi-2212) thin films fabrication by a metal organic decomposition method. When the Bi-2212 thin films were prepared on c-cut sapphire substrates, the maximum critical temperature (T_C) was 25 K by 820°C air annealing in an electric furnace for 30 min. When the Bi-2212 thin films were prepared on r-cut sapphire substrates with CeO₂ buffer layer, the Bi-2212 thin films were grown epitaxially on the CeO₂ buffer layer. The maximum TC obtained in the Bi-2212/CeO₂/r-cut sapphire was 62.5 K by 840°C air annealing in an electric furnace for 30 min. To improve the surface morphology, face-to-face annealing process was introduced for the Bi-2212/CeO₂/r-cut sapphire. By face-to-face annealing, TC was increased up to 65 K, and the critical current density of 1.03 × 10⁵ A/cm² was obtained at 5 K.