Planar transmission line resonators from YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films and epitaxial SIS multilayers

The authors have grown c-axis-oriented YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films and epitaxial YBCO/NdAlO/sub 3//YBCO trilayers by sputtering. From the YBCO films, coplanar half-wavelength transmission line resonators were patterned. At 77 K the unloaded quality factors of coplanar stripline resonators were up to 2570 at 5.6 GHz. The attenuation constant of such a line was evaluated to be 0.6 dB/m at 77 K and at 5.6 GHz. Coplanar waveguide resonators yielded quality factors up to 1200 at 77 K and at 6.2 GHz resulting in an attenuation constant of 1.8 dB/m. From these measurements the surface resistance values R/sub S/ of the films were determined. The lowest R/sub S/ was 105 mu Omega at 77 K and at 6.2 GHz. Trilayer structures with a dielectric as thick as 800 nm were patterned into microstrip resonators. At 50 K the authors measured a quality factor of 85 at 4.7 GHz, resulting in an attenuation of 26 dB/m and a surface resistance of 340 mu Omega . For thick dielectrics the upper YBCO film already contains significant portions of polycrystalline material.<>