Deposition of epitaxial YBCO thin film on single domain YBCO substrate for the development of RF components

The current trend of telecommunications has motivated an increasing need for an rf component of three-dimensional complex geometry in high-performance devices including tunable receivers, transformers, and inductors. In our previous work we have developed a novel substrateless cavity using single domain YBCO. This cavity resonator has been demonstrated to exhibit a high Q value at the rf frequency. The surface resistance of the single domain YBCO at 77 K has reached a low value of 500 :/spl Omega/ comparable to those of thin films (200 :/spl Omega/). However, in single domain YBCO, the second phase Y/sub 2/BaCuO/sub 5/ (211) is unavoidable in the peritectic reaction, which can, if not well controlled, cause severe dissipative losses. To further reduce the surface resistance, we have deposited an YBCO thin film on the single domain YBCO substrate covering all non-superconducting phases. The YBCO film and the substrate will have the best lattice matching since they are the same species. To study the epitaxial growth mechanisms, we have also deposited the YBCO film on other types of substrates including YSZ. Experimental results on film synthesis, interface structure, and superconducting properties are reported.