Inter-diffusion studies of SrBi2Ta2O9 film prepared on platinized wafer by pulsed laser ablation

Ferroelectric SrBi2Ta2O9 (SBT) thin films were prepared on platinized wafer— Pt/TiOx/SiO2/Si— by pulsed laser ablation deposition. Phase formation of SBT film was achieved during the deposition process itself, so the post-annealing that is often used by other groups is not necessary. The SBT film was well-crystallized, showing a dominant (115) peak at a deposition temperature as low as 580 °C, and exhibited good ferroelectric properties— the remanent polarization and coercive electrical field are 7.1 µC cm−2 (2Pr) and 30 kV cm−1, respectively, at an applied electrical field of 80 kV cm−1. Secondary ion mass spectrometry depth profiling and cross-sectional transmission electron microscopy were performed to study the inter-diffusion at the SBT/Pt bottom electrode interface. A sharp SBT/Pt interface was observed at a deposition temperature of 580 °C, but a higher deposition temperature (680 °C) resulted in significant inter-diffusion at the SBT/Pt interface. The formation of a secondary pyrochlore phase was observed due to Ti diffusion into SBT film at a high deposition temperature of 680 °C.