Effects of porosity on ferroelectric properties of Pb(Zr0.2Ti0.8)O3 films

The sol–gel deposition method has been successfully applied to obtain Pb(Zr0.2Ti0.8)O3 thin films on platinized silicon wafers. Addition of different amounts (7–15 wt.%) of organic macromolecular polyvinylpyrrolidone in the precursor solution prior to spin coating proves to be an excellent method for obtaining porous films. The crystal structure of as deposited films was analyzed by X-ray diffraction. The porous films show perovskite phase after annealing at 650 °C. The surface morphology has been studied by Atomic Force Microscopy and Scanning Electron Microscopy. The surface profile indicates a roughness of the film of 5 nm and no microcracks on the surface. The ferroelectric behavior was proved for each film, by hysteresis loops and by the “butterfly” shape of the capacitance–voltage characteristics. The remnant polarization and the coercive field decrease while the amount of added PVP increases.