YBa2Cu3O7-x thin films and YBa2Cu3O7-x/CeO2 heteroepitaxial structures grown on YSZ substrates by pulsed injection CVD

The in situ synthesis of thin YBa2Cu3O7-x (YBCO) films and YBCO:CeO2 hetero structures was carried out on (001) ion mass spectrometry (SIMS) concentrat ion profiles revealed a diffusion of Zr from the unbuffered substrate to th e films. Zr(Y)O-2. (YSZ) substrates from the organometallic vapor phase by a new pulsed injection CVD technique. The secondary The films had a dominat ing (001) texture and a dominating 45 degrees in-plane orientation, but oth er orientations (0 degrees, 9 degrees, 36 degrees) were also not infrequent in the films. The vapor phase composition was found to have a great influe nce on the film microstructure and critical parameters. The critical temper atures (T-c) of the best YBa2Cu3O7-x films were about 90 K, the critical cu rrent densities (J(c)) being similar to 4 x 10(5) A cm(-2) at 77 K, A thin epitaxial CeO2 layer grown in situ before YBCO deposition stopped the Zr di ffusion from the substrate and dramatically improved the epitaxy and critic al parameters of YBCO films. The T-c (Delta T-c) and J(c) of the deposited YSZ/CeO2/YBCO heteroepitaxial structures equaled similar to 90 K (similar t o 0.3 K) and similar to 4 x 10(6)A cm(-2) at 77 K. This result shows that a simple deposition of an intermediate CeO2 layer before the growth of YBCO makes YSZ substrates very competitive with perovskite substrates.