Superconductor-Ferroelectric-Superconductor Trilayers for Novel Tunable Microwave Devices

This effort will develop tunable microwave resonators based on high temperature superconductor (HTS) multilayer technology, which will form the basic building block for a new generation of advanced communications filters. The proposed work will contribute to the growth of wireless communications for both military and commercial sectors. At Superconductor Technologies, Inc. (STI), thick trilayers utilizing YBa2Cu3)7-x (YBCO) HTS and NdAlO3 dielectric layers have been developed with performance superior to the existing state-of-the-art. In addition, trilayer resonators orders of magnitude smaller than conventional devices have been demonstrated. Tunability of trilayer resonators will be achieved in the proposed program by moving to SrTiO3 as the dielectric, which is ferroelectric. Phase I research will focus on demonstrating a novel microwave resonator with HTS/SrTiO3/HTS trilayers. Trilayer properties relevant to the device will be measured. The device will be fabricated, tested, and modeled, and the loss tangent measured over a wide range of temperatures. The tunability of the resonators will be simulated using experimentally confirmed properties of trilayers. These structures will ultimately enable frequency agile filters with orders of magnitude higher selectivity than is possible with existing filter technologies, and simultaneously reduced component volume. Beneficial to civilian cellular and PCS providers, and military units, who need high performance tunable filters to reduce interference and improve jamming resistance. HTS trilayer tunable filters will meet customer needs of frequency agility, reduced interference, improved communication range, increased mobility, and reduced service & environmental costs. Potential markets are about $1B/yr in each of military and commercial sectors.