MORPHOLOGICAL AND STRUCTURAL-PROPERTIES OF HIGH-QUALITY YBCO THIN-FILMS

High-quality YBCO thin films have been grown by Inverted Cylindrical Magnetron Sputtering (ICMS) on LaAlO3(100), SrTiO3(100), SrTiO3(110), and MgO(100) substrates. Transition temperaturs of c-axis films exceed 90 K, and transition widths are within 1 K. Critical currents range up to 5 x 10(6) A/cm2 at 77 K. Structural and morphological features analyzed by x-ray diffraction and scanning electron microscopy, respectively, are found to be strongly dependent on film orientation and deposition temperature. In order to understand such dependence, a simple interpretation is proposed in terms of Gibbs energies and growth dynamics of the nucleation process.