Atomic force microscopy of porous ferroelectric PZT films

Abstract

The surface topography, local current distribution and piezoresponse signal in porous ferroelectric PZT films are studied using conductive atomic force microscopy (c-AFM) and piezoforce microscopy (PFM). The PZT films were formed from solutions with the addition of 0–20 wt% polyvinylpyrrolidon (PVP) as a porogen with the molecular weight of 360000. Applying c-AFM, the topography images and distribution maps of the local current of the same surface area are obtained, which made it possible to compare the profiles of the topography and current signals. It is shown that in PZT films prepared without PVP addition, the local currents flow inside the grains forming the columnar structure with nonconductive grain-boundaries. At PVP content of 1-3 wt%, separate current peaks are observed on the analyzed profiles, but starting from 6 wt% PVP and higher, the local current flowing in the pore regions exceeds the current recorded in the grain area.