INFLUENCE OF AL2O3 DIFFUSION BARRIER AND PBTIO3 SEED LAYER ON MICROSTRUCTURAL AND FERROELECTRIC CHARACTERISTICS OF PZT THIN-FILMS BY SOL-GEL SPIN-COATING METHOD

Sol-gel spun-casted Pb(Zr0.52Ti0.48)O-3 [PZT] thin film with Al2O3 buf fer layer and PbTiO3 seed layer was successfully prepared at a low tem perature of 550 degrees C. Al2O3 buffer layer, as a diffusion barrier between the silicon substrate and the Pt bottom electrode, suppressed interface reactions between the film and the substrate and prevented t he interdiffusion of Pb and Si elements. PbTiO3 seed layer between the Pt bottom electrode and the PZT thin film promoted the formation of p erovskite phase at lower temperature due to the presence of ample nucl eation sites. The microstructure of the PZT thin film is composed of h omogeneous submicron grains. Dielectric constant and tan delta of the PZT thin film with the buffer and the seed layer were enhanced by 3-5 times in comparison to the PZT film wthout the buffer and the seed lay er. Typical P-E hysteresis behavior was observed even at applied volta ges as low as 5 V, manifesting greatly improved remanent polarization and coercive field. Fatigue characteristic, measured at 7 V, showed st able behavior. Degradation in polarization was found to be less than 5 % at 10(8) cycles. (C) 1997 Published by Elsevier Science S.A.