Frequency dependence of anomalous shift and polarization retention loss in ferroelectric capacitors

A unified model which takes into account an interfacial layer between electrode and ferroelectric film has been developed to study the fatigue, imprint and retention failures of ferroelectric capacitors. The anomalous shift of the hysteresis loops observed experimentally has been correctly reproduced with this model. It is found that such a shift is strongly dependent on the thickness ratio υ of the interfacial layer to the bulk film, as well as on the frequency of the external applied field. Furthermore, the model, when combined with the Schottky emission, can also properly describe the retention loss in polarization. Theoretical predictions based on this approach may provide a method to reduce the failure of ferroelectric capacitor.