Buffers for high temperature superconductor coatings. Low temperature growth of CeO2 films by metal-organic chemical vapor deposition and their implementation as buffers

Smooth, epitaxial cerium dioxide thin films have been grown in-situ in the 450-650 degrees C temperature range on (001) yttria-stabilized zirconia (YS Z) substrates by metal-organic chemical vapor deposition (MOCVD) using a ne w fluorine-free liquid Ce precursor. As assessed by X-ray diffraction, tran smission electron microscopy (TEM), and high-resolution electron microscopy (HREM), the epitaxial films exhibit a columnar microstructure with atomica lly abrupt film-substrate interfaces and with only minor bending of the cry stal plane parallel to the substrate surface near the interface and at the column boundaries. With fixed precursor temperature and gas flow rate, the CeO2 growth rate decreases from similar to 10 Angstrom/min at 450 degrees C to similar to 6.5 Angstrom/min at 540 degrees C. The root-mean-square roug hness of the films also decreases from 15.5 Angstrom at 450 degrees C to 4. 3 Angstrom at 540 degrees C. High-quality, epitaxial YBa2C3O7-x films have been successfully deposited on these MOCVD-derived CeO2 films grown at temp eratures as low as 540 degrees C. They exhibit T-c = 86.5 K and J(c) = 1.08 X 10(6) A/cm(2) at 77.4 K. (C) 1999 Published by Elsevier Science B.V. All rights reserved.