Voltage tunable capacitors using high temperature superconductors and ferroelectrics

In this paper we report the construction of both slot capacitors on bulk substrate and thin film interdigital capacitors using YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) and Ba/sub x/Sr/sub 1-x/TiO/sub 3/. Slot capacitors made on bulk Ba/sub x/Sr/sub 1-x/TiO/sub 3/ (BST) yielded variations in capacitance of more than 6 to 1 at 86 K with a peak electric field strength of 25 kV/cm. With a metal organic deposition (MOD) grown Ba/sub x/Sr/sub 1-x/TiO/sub 3/ 300-nm overcoat on a YBCO thin film, an interdigital capacitor on LaAlO/sub 3/ substrate yielded an approximate tuning range of 10% for peak field of 66 kV/cm over temperatures ranging from 50 K to 120 K.<
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