GROWTH AND CHARACTERIZATION OF BSTO AND YBCO BSTO THIN-FILMS ON MGO(100) SUBSTRATES/

By using pulsed laser deposition (PLD), we prepared Ba0.5Sr0.5TiO3 (BS TO) films with different film thickness up to 300 nm and YBa2Cu3O (YBC O)/BSTO and BSTO/YBCO thin films on single crystal MgO(100) substrates . BSTO film was epitaxially grown in the c-axis orientation for T-grow th greater than or equal to 700 degrees C while it was rather grown in a mixed crystalline orientation for T-growth < 700 degrees C BSTO/MgO surface was very smooth without showing any noticeable grain features , particularly for the film grown at T-growth = 700 degrees C Also, YB CO on BSTO/MgO was epitaxially grown and BSTO on YBCO/MgO as well. Usi ng scanning electron microscopy (SEM), we found that the film surface morphology depended significantly upon the order of layering of YBCO a nd BSTO.