PATTERNING OF TUNABLE PLANAR FERROELECTRIC CAPACITORS BASED ON THE YBCO BSTO FILM STRUCTURE/

Superconductor/ferroelectric (SF) and normal conducting metal/ferroele ctric (NF) film structures were grown using DC and RF magnetron sputte ring of ceramic YBa2Cu3O7-delta and BaxSr1-xTiO3 targets. Low-energy i on beam etching was used for patterning an SF planar capacitor with an electrode gap of about 1.5 mu m. Ferroelectric films displayed a rath er smooth temperature dependence of epsilon with a maximal value of ab out 850 at T similar to 260 K (tan delta similar to 0.02). Planar ferr oelectric capacitors were intended for application in microwave tunabl e devices, so structures without hysteresis in voltage-capacitance cha racteristics were demanded. The SF and NF structures demonstrated a hi gh enough coefficient of capacitance tuning (more than 1.5) and lower hysteresis for structures with YBCO electrodes.