Scanning force microscopy investigation of the Pb(Zr0.25Ti0.75)O3/Pt interface

We report on a novel approach for the investigation of the Pb(ZrxTi1−x)O3/Pt interface applying scanning force microscopy techniques. Ferroelectric samples (PZT film /Pt/SiO2/Si) were polished at a shallow angle (∼6.1°) thereby enlarging the film cross section from a 430 nm film thickness to a width of more than 4 μm. Piezoresponse force microscopy and Kelvin probe force microscopy were applied in order to deduce the dielectric polarization P and local potential distribution over the full cross section. We clearly observe a transition layer with a thickness of ∼240 nm which manifests itself both in a gradual decrease of the piezoresponse signal as a function of film thickness and in a corresponding variation of the surface potential. Furthermore, after polarization reversal due to a dc voltage applied to the tip, a different retention behavior was observed within the transition layer. The results are tentatively attributed to negatively charged defects accumulated at the PZT/Pt interface.