Polarization recovery of fatigued Pb(Zr,Ti)O3 thin films: Switching current studies

Abstract

In the process of fatiguing Ir/Pb(Zr0.35Ti0.65)O3/Pt capacitors we have observed the splitting and separation of both the positive and negative switching currents into two distinct peaks. By measuring the current response to a post-fatigue, triangular, voltage waveform, we have observed a shift of the majority of the switching current to higher voltages and, eventually, beyond the voltage testing range. At high fatigue cycle numbers, this current peak shift is large enough to reveal a smaller switching current peak whose position remains invariant. Subsequent higher amplitude switching pulses access the high coercive voltage switching peaks, returning the remanent polarization values, though not the overall switching profile, to unfatigued levels. Pulse polarization measurements reveal that the switchable polarization that appears lost at lower testing voltages is highly recoverable when higher voltages are applied. Thus, the fatigue cycling appears to primarily increase the polarization switching resistance while inducing very little irrecoverable switching loss. Finally, we measured increased resistance to switching with fatigue cycling even when the majority of the capacitor volume was no longer switching during the fatigue pulses, suggesting that only voltage cycling, and not the concomitant polarization switching, are necessary to induce fatigue.