Published online by Cambridge University Press: 17 March 2011
Imprint describes an aging effect in ferroelectric thin films which manifests itself by a shift of the P-V hysteresis loop on the voltage axis. In this paper a mechanism is described which attributes imprint to the screening of a large electric field within a thin surface layer by electronic charges. The field at the surface arises due to the existence of a thin surface layer in which the spontaneous ferroelectric polarization is suppressed. In the course of aging this field is gradually screened by electronic charges which are generated by a Frenkel-Poole effect and then become trapped near the electrode-thin-film interface causing the shift of the hysteresis loop. A numerical simulation based on this model allows a quantitative description of the imprint effect as a function of various experimental parameters.