OFF-AXIS SPUTTER DEPOSITION OF YBA2CU3O7 THIN-FILMS FOR MICROWAVE APPLICATIONS

Thin films of superconducting YBa2Cu3O7 were grown in situ by off-axis sputter deposition for microwave device fabrication. These approximately 1 cm2 films, which are reproducible, exhibit midpoint T(c)'s of 89-90.5 K as measured by ac susceptibility, ion channeling yields of 4.7%-6%, and c-axis rocking-curve half-widths of 0.5-degrees, even with a rich microstructure as seen by scanning electron microscopy. Two films were photodefined into miniature X-band microwave bandpass filters. These narrow-band filters (0.5% bandwidth) exhibited 4.4- and 4.5-dB insertion losses at 77 K and 9.25 GHz, with little temperature dependence below 80 K.