MICROSTRUCTURE AND SUPERCONDUCTING PROPERTIES OF THIN-FILMS OF YBCO ON (100) MGO SUBSTRATE GROWN BY GLOW-DISCHARGE DEPOSITION

Direct growth of YBa2Cu3O7-x superconducting thin films on (100) MgO single crystal substrate has been achieved by a glow discharge sputtering process from a single target of stoichiometric compound. Films have been deposited in the temperature range of 923-973 K and oxygenated al 673 K in a single uninterrupted cycle. The YBa2Cu3O7-x films prepared under optimum processing conditions have a strong texture (c-axis perpendicular to film plane), have transition temperatures at zero resistance of 86 K and the width of transition of about 2 K. The films have transport critical current density of about 5 X 10(5) A/cm2 at 77 K and 2 X 10(6) A/cm2 at 50 K at zero magnetic field. The processing conditions and relation between the microstructures and superconducting properties have been studied in detail. It is shown that the microstructure corresponding to the best superconducting properties is a basket weave microstructure at the resolution limit of an optical microscope.