SPUTTER DEPOSITION OF ORIENTED Y-BA-CU-O THIN-FILMS AND STUDY OF GRAIN-BOUNDARY JOSEPHSON-JUNCTIONS

Superconducting thin films of Y-Ba-Cu-O were prepared using high pressure (greater-than-or-equal-to 100 mTorr) rf magnetron sputtering. The resputtering effects due to presence of negative ions were almost eliminated. The films grown on (100)SrTiO3 were highly a-axis oriented while films grown on (100)MgO and (100)YSZ, under identical conditions were highly c-axis oriented. Resistance vs. Temperature measurements of the films showed a Tc (R = 0) between 85 to 90K. Microbridges were patterned on these films and microwave induced Shapiro steps due to ac Josephson effect in the grain boundary weaklinks were clearly observed in their I-V characteristics.