Discrimination between bulk and interface scenarios for the suppression of the switchable polarization (fatigue) in Pb(Zr,Ti)O3 thin films capacitors with Pt electrodes

A simple and reliable method which allows one to distinguish between the two major microscopic scenarios for the suppression of the switching polarization ${\mathrm{(P}}_r^s\mathrm{),}$ i.e., pinning of ferroelectric domain walls (DWs) through the ${\mathrm{Pb(Zr,Ti)O}}_{\mathrm{3}}$ film (PZT) (bulk scenario) and inhibition of the growth of opposite domains due to the nucleus suppression at the electrode interfaces (interface scenario), is proposed. In addition, a new electric treatment able to significantly suppress $P_r^s$ in Pt–PZT–Pt ferroelectric capacitors (FECAPs) of thicknesses above 1.4 μm, was discovered and studied. It consists of the application of an external alternating electric field ${\mathrm{(E}}_e)$ which cycles the polarization at very low frequency (1.7 mHz). After only 10–20 cycles, $P_r^s$ can be suppressed by a factor of 10. The same FECAP, when subjected to $E_e$ at higher frequency (30 kHz), endures at least ${10}^8$ switches, before attaining an equivalent $P_r^s$ suppression (hereafter called fatigue). The fatigued states obtained with the two different procedures appear to be different. In the first case (slow cycling) it is suggested that the suppression of $P_r^s$ is related to the DW pinning scenario, whereas in the second case—which corresponds to the normal fatiguing procedure—it is related to the interface scenario.