STUDIES ON EPITAXIAL-GROWTH OF YBCO THIN-FILMS DEPOSITED IN-SITU BY DC MAGNETRON SPUTTERING

High-T(c) superconducting YBCO thin films have been deposited in situ on (001) MgO and (1102) alpha-Al2O3 with MgO buffer layer substrates by dc magnetron sputtering. The microstructure of YBCO thin films has been studied by X-ray diffraction. 8-28 diffraction scans have been used to identify the phase and orientation of the thin films. Rocking curves are used to study the alignment of c-axis of the films. The in-plane orientation of lattice vectors have been identified by X-ray pole figures. The microstructural studies have revealed that three-dimensional alignment of thin film and substrate lattice vectors are essential to obtain high J(c) in thin films. The critical current density J(c) of such films deposited on (001) MgO, which are c-axis oriented and also have in-plane alignment is of the order of 1 x 10(6) A/cm2 at 77K in zero magnetic field while J(c) of the films deposited on MgO/alpha-Al2O3 substrate, which are c-axis oriented but do not have in-plane alignment only is found to be 2 x 10(4) A/cm2 at 77 K in zero field.