PREPARATION AND CHARACTERIZATION OF YBACUO HIGH T-C SUPERCONDUCTING THIN-FILMS

For thin film metalorganic chemical vapor deposition (MOCVD), a stoich iometric gas phase can be obtained from a mixture of the precursors in the desired mole ratios, in spite of differences in the volatilities of the individual compounds. Proper film composition is obtained by co ntrolling the velocity of a carriage containing the precursors through the heating zone of a vaporizer. YBaCuO (YBCO) superconducting films were prepared on yttrium stabilized zirconia (YSZ) (001) crystal subst rates by single source MOCVD using a mixture of powders of Y(thd)(3), Ba(thd)(2) and Cu(thd)(2) as sources. Nondestructive measurements of r esistivity, critical current, composition, and surface morphology were performed on these films, A single crystal film with T-co = 89 K was made under optimum conditions. Its homogeneity was investigated by res istivity and T-co measurements and by atomic force microscopy (AFM) at several points of the surface along a diameter of this film. The roug hness of the film is higher at the edge than at the center, and this a ppears to be correlated with the normal state resistivity. The c-axis and a-axis YBCO phases compete with each other at substrate temperatur es ranging from 750 to 820 degrees C. The c-axis YBCO phase shows spir al growth structure and the spiral step height is about 12 Angstrom.