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

High-quality YBCO thin films have been grown by Inverted Cylindrical M agnetron Sputtering (ICMS) on LaAlO3(100), SrTiO3(100), SrTiO3(110), a nd 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 ana lyzed by x-ray diffraction and scanning electron microscopy, respectiv ely, are found to be strongly dependent on film orientation and deposi tion temperature. In order to understand such dependence, a simple int erpretation is proposed in terms of Gibbs energies and growth dynamics of the nucleation process.