Thickness effects on imprint in chemical-solution-derived (Pb, La)(Zr, Ti)O-3 thin films

The film thickness-dependent imprinting behavior (voltage shift) of (Pb, La )(Zr, Ti)O-3 capacitors was evaluated by a thermal stress process under a r emanence bias. The remanent polarization (P-r) was found to be almost indep endent of the film thickness whereas in the 50-300 nm range the relative di electric constant (epsilon (r)) increased linearly with the square root of the film thickness. It was found that the voltage shift, which was attribut ed to the accumulation of charged defects near the electrode interface, als o increased linearly with increasing film thickness. In addition, the charg e accumulated thickness varied with the square root of the film thickness. This was established from a simple assumption that the level of charge accu mulation is determined by the product of the total amount of charged defect s (total film thicknessxcharged defect density) and the internal field that is generated by the P-r. Therefore, the imprint is much more a bulk-relate d degradation phenomenon compared to the fatigue. (C) 2001 American Institu te of Physics.