The influence of non-ferroelectric interface layers and inclusions on the imprint behavior of ferroelectric thin film capacitors

Based on the Arlt model of the aging mechanism in ferroelectric bulk ceramics it will be shown that in thin films the alignment of defect dipoles with the orientation of the surrounding ferroelectric dipoles could be responsible for the imprint. The driving force of the alignment is related to the spontaneous polarization of the ferroelectric. Due to the existence of non-ferroelectric interface layers or inclusions, depolarization occurs which could be observed by a deformation of the hysteresis loop ("shearing"). The proposed mechanism predicts that the imprint is reduced with higher depolarization effects. The suggestion is verified by imprint measurements of a thickness series of PZT thin film capacitors.