High energy oxygen ion induced modifications in lead based perovskite thin films

The lead based ferroelectric PbZr0.53Ti0.47O3 (PZT), (Pb0.90La0.10)TiO3 (PLT10) and (Pb0.80La0.20)TiO3 (PLT20) thin films, prepared by pulsed laser ablation technique, were studied for their response to the 70 MeV oxygen ion irradiation. The dielectric analysis, capacitance-voltage (C- V) and DC leakage current measurements were performed before and after the irradiation to high-energy oxygen ions. The irradiation produced considerable changes in the dielectric, C-V, leakage characteristics and induced some amount of amorphization. The PZT films showed partial recrystallization after a thermal annealing at 400 degrees C for 10 min. The phase transition temperature [T-c] of PLT20 increased from 115 degrees C to 120 degrees C. The DC conductivity measurements showed a shift in the onset of non-linear conduction region. The current density decreased by two orders of magnitude after irradiation. After annealing the irradiated films at a temperature of 400 degrees C for 10 min, the films partially regained the dielectric and electrical properties. The results are discussed in terms of the irradiation-induced amorphization, the pinning of the ferroelectric domains by trapped charges and the thermal annealing of the defects generated during the irradiation. (C) 2007 Elsevier B.V. All rights reserved

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

Pb(Zr_{0}_{.53}Ti_{0}_{.47})O_{3 }(PZT) and $SrBi_{2}Ta_{2}O_{9 }$(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 $1*10^{12}$ to $1-10^{14}$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

High Energy Oxygen Ion Induced Modifications in Ferroelectric SrBi2Ta2O9SrBi_{2}Ta_{2}O_{9} Thin Films

The effects of high energy oxygen ion irradiation on the ferroelectric properties of $SrBi_{2}Ta_{2}O_{9}$ (SBT) thin films are reported. The films were grown using pulsed laser ablation. Fluence dependant degradation in the ferroelectric properties was observed. The dielectric constant did not show any frequency dispersion in both the unirradiated and irradiated films. After irradiation, the films showed only a decrease in the capacitance value retaining their ferroelectric nature. The switching voltages increased with broader peaks and showed a partial recovery after annealing of the irradiated film. A slim hysteresis loop with decreased $P_{s}$, $P_{r}$ and $E_{c}$ values was observed. The current density increased to a larger extent. The decrease in the dielectric constant, capacitance and polarization values was to a lesser extent as compared to those of PZT thin films under identical irradiation conditions. The results presented in this paper are illustrative of the fact that the layered perovskites have a stable structure and are less sensitive to extrinsic effects. The relatively high resistance of bismuth layered perovskites such as SBT to the high energy radiation along with the greater fatigue endurance as compared to PZT make them better candidates for applications in memory devices