Diffusion processes in seeded and unseeded SBT thin films with varied stoichiometry

SrBi2Ta2O9 (SBT) is a bismuth layered perovskite (BLP) with interesting ferroelectric properties for memories applications. The previous study on the synthesis of seeded and unseeded SBT thin films by the authors [G. González Aguilar, M.E.V. Costa, I.M. Miranda Salvado, J. Eur. Ceram. Soc. 25 (2005) 2331] has shown an increase of the crystallinity of the films and an improvement of the thin film ferroelectric properties when using SBT seeds. However, the detailed role of the seeds as an improver of the thin film properties has not been investigated so far. In the present work we study the role of the seeds, particularly with respect to the reactions between film and (bottom) underlying platinum electrode. The comparison of the results obtained by characterizing the seeded and unseeded thin films via Rutherford backscattering (RBS) and particle induced X-ray emission (PIXE) techniques reveals an effective modification of the substrate–thin film interface by the presence of the seeds. Moreover, the evaluation of the thin film ferroelectric properties by atomic force microscopy (AFM) shows an improvement of the local piezoelectric hysteresis loops by the seeds. These seeding effects as well as those observed in non-stoichiometric SBT thin films with different bismuth contents are used to discuss the barrier-like role of the SBT seeds against reactions between film and the platinum electrode and its contribution to the improvement of the thin film properties.