Thermally Stimulated Current and Polarization Fatigue in Pb(Zr,Ti)O3 Thin Films

In order to clarify the origin of the polarization fatigue phenomena, charge traps in ferroelectric Pb(Zr,Ti)O3 (PZT) thin films were measured using the thermally stimulated current (TSC) technique. For polarization fatigued Pt/PZT/Pt/SiO2/Si(100) capacitors, a peak of TSC was observed, and the trap density estimated from the TSC data increased as switching cycles increased. Activation energy and density of the charge traps were estimated to be 0.7–0.8 eV and on the order of 1018 cm-3, respectively. It was also observed that degradation of remanent polarization of PZT was improved by the TSC measurement process. On the other hand, no TSC peak was observed for fatigue free Ir/PZT/Ir/IrO2/SiO2/Si(100) capacitors. From these results, it was suggested that the main origin of the polarization fatigue phenomena was the domain pinning caused by trapped charge carriers injected by polarization reversal.