Characteristics of SrBi2Ta2O9 thin films prepared by pulsed laser deposition for non-volatile memory applications

Ferroelectric SrBi2Ta2O9 (SBT) thin films were prepared on Pt/TiO2/SiO2/Si( 100) substrates by pulsed laser ablation of SrBi2.2Ta2O9 ceramic target. Th e ferroelectric properties and microstructure of SET films were investigate d in this work. The SBT films deposited at 650 degreesC exhibited a remnant polarization of 6.6 muC/cm(2) and a coercive field of 23 kV/cm at 5 V. Hig her leakage current was observed in films deposited at 550 degreesC. Crysta llinity of the films was examined by X-ray diffraction patterns and no seco ndary phases were observed. Furthermore, XRD patterns also indicated a chan ge in orientation from c-axis dominated to randomly polycrystalline, when t he deposition temperature was changed from 550 to 650 degreesC. Grains in S ET film show polyhedral morphologies based on planar TEM analysis. The micr ostructures of grain boundaries in SET him with c-axis dominated orientatio n were investigated by high-resolution transmission electron microscopy (HR TEM). The relationship between the leakage current of film and microstructu res of grain boundaries is briefly discussed. (C) 2000 Elsevier Science S.A . All rights reserved.