Characterization of Switching Properties of Lead-Zirconate-Titanate Thin Films in Ti-Rich Phase

Switching behaviors of lead-zirconate-titanate thin-film capacitors with Ti/Zr ratios of 60/40 and 75/25 were successfully characterized by observing their switching transient currents. The capacitor with 60/40 showed the remanent polarization density of 24.0 µ/cm2 independent of the frequency of the external switching biases. On the other hand, the remanent polarization density of the capacitor with 75/25 was reduced markedly with increasing the frequency. The remanent polarization density was lowered from 23.6 µC/cm2 at 100 Hz to 13.0 µC/cm2 at 12.5 kHz. While the switching transient currents were observed as a function of time, the lead-zirconate-titanate thin-film capacitor with 60/40 showed the typical sharp switching transient current. In sharp contrast, the capacitor with 75/25 ratio showed a monotonous transient current which suggests the presence of ferroelectric domains having long time constants. Consequently, the lead-zirconate-titanate thin film with the Ti/Zr ratio of 60/40 showed better switching behavior as compared to that with the Ti/Zr ratio of 75/25.