Electrical characterizations of polycrystalline and amorphous thin films of Pb(ZrxTi1−x)O3 and BaTiO3 prepared by sol—gel technique

Abstract

Abstract Amorphous and polycrystalline thin films of ferroelectric oxides for lead zirconate titanate [Pb(Zr x Ti 1− x )O 3 or PZT] and barium titanate (BaTiO 3 ) on several kinds of substrate (metals and silicon wafer) were prepared by the sol—gel technique. The heat-treatment temperatures for preparation of amorphous thin films were much lower than those for the corresponding polycrystalline ferroelectric thin films. Electrical properties of these amorphous thin films were measured and compared with those of corresponding polycrystalline films. The dielectric permittivity of amorphous thin films is apparently smaller than that of the corresponding polycrystalline thin films. In both polycrystalline and amorphous thin films some piezoelectric resonance peaks were observed. These amorphous thin films exhibited pyroelectric effects and P  E hysteresis loop. The electrical ferroelectric-like properties indicate that there is a permanent polarization, which can be reversed by external field, in the amorphous thin films. By using the HRTEM (high resolution transmission electron microscope) technique some small ordered clusters (ferrons) with size of 3 to 5 nm in the amorphous thin films were directly observed. The electrical ferroelectric-like properties of the amorphous thin films can be explained by the ferrons' structure.