PLANAR TRANSMISSION LINE RESONATORS FROM YBA(2)CU(3)O(7-x) THIN FILMS AND EPITAXIAL SIS MULTILAYERS

We have grown c-axis oriented YBa2Cu3O7-x (YBCO) thin films and epitaxial YBCO/NdAlO3/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-s of the films were determined. The lowest Rs 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 we 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.