Characteristics of Au/PbZr_0.52Ti_0.48O₃/YBa₂Cu₃O_7−δ capacitors fabricated on LaAlO₃ and Y₂O₃-stabilized ZrO₂ substrates during irradiation

Abstract

PbZr_0.52Ti_0.48O₃ (PZT)/YBa₂Cu₃O_7−δ (YBCO) structures were fabricated on LaAlO₃ and Y₂O₃-stabilized ZrO₂ (YSZ) substrates by a pulsed-excimer-laser deposition method. The total dose effects on the Au/PZT/YBCO ferroelectric capacitors were considered by measuring the capacitance-voltage (C-V) characteristics and the retained polarization properties of the capacitor before and after γ-ray irradiation. The results show that, with an increase of irradiation dose, for a ferroelectric capacitor which was fabricated on a LaAlO₃ substrate, the retained polarization ΔP and the dielectric constant ε decreased, but the absolute value of the negative and positive coercive fields increased. For a ferroelectric capacitor which was fabricated on a YSZ substrate, ΔP and ε also decreased while the coercive fields drifted towards the positive voltage direction. All these facts are due to the effect of charges trapped by defects in the PZT layer and the interface of the capacitor during irradiation.