Impact of face-to-face annealing in preparation of sol-gel-derived SrBi2Ta2O9 thin films

An annealing method for preparing SrBi2Ta2O9 (SBT) thin films, a face-to-face annealing method, is proposed, and its effectiveness is demonstrated. In this method, an SBT film deposited on a substrate using a sol-gel technique was directly put with the film side down on the other SBT film during crystallization process. The SBT films were crystallized at 750 °C in an oxygen flow and successively annealed at 400 °C in a 6.2 wt % ozone flow. It was found that remanent polarization value (2Pr) in a 175-nm-thick SBT film was as large as 23 μC/cm2 when the face-to-face annealing method was conducted. It was also found from time-dependent leakage current measurement that the leakage current density of the films was lower than 1×10−9 A/cm2 at an electric field of 65 kV/cm.