Voltage tunable capacitors using high temperature superconductors and ferroelectrics

Abstract

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.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>