ORIGIN OF DEPOLARIZATION IN SOL-GEL FERROELECTRIC PB(ZR0.4TI0.6)O-3 THIN-FILM CAPACITORS

We evaluated depolarization characteristics of sol-gel Pb(Zr0.4Ti0.6)O-3 ferroelectric thin-film capacitors. The depolarization characteristics were strongly dependent upon the capacitance of the load capacitor. The newly obtained hysteresis loop during the pulse response indicates that significant voltage of opposite direction is generated on the ferroelectric capacitor at the moment the read pulse becomes zero. We experimentally found that the mechanism of depolarization is based on depoling (or partial switching) by an opposite-direction voltage arising from accumulated switching charge on a load capacitor. This mechanism can be easily extended to the internal depolarization effect due to the interfacial linear capacitor between the ferroelectric region and electrode.