FATIGUE AND REFRESH CHARACTERISTICS OF PB(ZR0.52TI0.48)O-3 THIN-FILMS

Pb(Zr0.52Ti0.48)O-3(PZT) and Nd-doped PZT(PNZT) thin films prepared by the sol-gel technique were fatigued by bipolar switching pulses up to 10(9) cycles. The switchable polarization for both thin films exhibit ed a fast decay around 10(6) cycles. For refreshment of the thin films , +/-19 V DC bias voltages were applied to the top electrode of the fa tigued thin films, and then the D-E hysteresis loop was re-measured. W hen a -19 V DC bias voltage was applied to the top electrode, the fati gued samples recovered, while the samples to which a +19 V DC bias vol tage was applied did not recover. These results qualitatively show tha t the refreshment of the switchable polarization can be attributed to the diffusion of the oxygen vacancies accumulated at the bottom interf ace toward the bulk of the thin film as a result of the application of the -19 V bias. Therefore, the dominant fatigue mechanism for the PZT thin films was confirmed as the accumulation of oxygen vacancies at t he interface rather than the domain wall pinning seen in the thin film s. Furthermore, the coercive field after fatigue and refresh increased compared with its initial value.