Ac conductivity studies on the Li irradiated PZT and SBT ferroelectric thin films

Abstract

Pb(Zr_0.53Ti_0.47)O₃ (PZT) and SrBi₂Ta₂O₉ (SBT) ferroelectric thin films were prepared on Pt coated Si substrates by pulsed laser ablation technique and their responses to the high energy Lithium ion irradiation were studied in terms of their ac conductivity, dielectric studies, polarization hysteresis and structural properties. The PZT and SBT thin films were fabricated in Metal-Insulator-Metal capacitor configuration and were irradiated with the 50 MeV Lithium ions with varying fluence from 1×10¹² to 1×10¹⁴ ions cm^-2. The ferroelectric properties were observed to be degraded by the irradiation. The ac conductivity of the films was explained by the charge carrier hopping model. Irradiated PZT thin films exhibited a significant variation on the frequency dependent exponent(s) while the irradiated SBT thin films had a negligible influence. The activation energy calculated from the Arrhenius plots was found to increase from 1.05 to 1.55 eV for PZT and from 0.85 to 0.91 eV for SBT thin film after irradiation. These energies were attributed to the oxygen vacancies and the deep trap carriers induced by the irradiation.