Growth Mechanism of YBa2Cu4O8(124) Phase in Metalorganic Chemical Vapor Deposition Film

Recently, we reported that Y-Ba-Cu-O superconducting films containing the 124 phase were fabricated by MOCVD below 800°C without post annealing. In this study, efforts were focused on clarifying when the 124 phase appears and how the 124 grain grows. From annealing experiments, it is clear that the 124 phase is not formed as a result of solid state reaction, but it grows during deposition. The results from different deposition times under the same conditions, show that the upper part and the lower part of the film consist differently, and that in the part near the film surface, 124 is the main phase.