Effects of Y2O3 layer on the growth of YBa2Cu3O7-y thin film by metal organic chemical vapor deposition

Epitaxial c-axis oriented YBa2Cu3O7-y (YBCO), superconducting films have been grown by metal organic chemical vapor deposition (MOCVD) on MgO substrate covered with a Y2O3 layer, which was also deposited by MOCVD. It was observed that the {n00} texturing of the Y2O3 layer became predominant at 650-680 degrees C. The YBCO film on that layer was c-axis oriented and showed good in-plane alignment. From TEM images, we confirmed that the YBCO film grew on top of the MgO substrate, even if the Y2O3 buffer layer was fabricated before the YBCO deposition. Furthermore, the YBCO film did not involve grain boundaries. It was considered that the Y2O3 was incorporated into YBCO film during deposition and the lattice mismatch between YBCO and MgO was improved by depositing the Y2O3 buffer layer. The T-c(zero) of YBCO film was found to be 90 K. (C) 2000 Elsevier Science B.V. All rights reserved.