Improved electrical properties of Sr0.8Bi2.2Ta2O9 films by ZrSiO4 doping for low voltage operations of metal-ferroelectric-insulator-Si devices

Sr0.8Bi2.2Ta2O9 (SBT) films were prepared by chemical solution deposition in which ZrSiO4 (ZSO) with concentration ranging from 0 to 10 wt % was incorporated for improving dielectric and leakage current characteristics of the films. X-ray diffraction analysis revealed that no secondary phase and clear degradation of crystallization can be found in ZSO-doped SBT films. Smaller grain size and reduced surface roughness were found for the samples with higher ZSO doping concentration as observed by atomic force microscopy and scanning electron microscopy. The dielectric constant was observed to be much reduced for ZSO-doped SBT films as well as the remnant polarization and coercive field. Films preannealed at 400 degrees C have a much smaller dielectric constant when compared with that of the films preannealed at 750 degrees C. Furthermore, a clear reduction in the leakage current and improved fatigue characteristics were observed for ZSO-doped SBT films preannealed at 400 degrees C. Such improved electrical properties as reduced dielectric constant, leakage current, and coercive field for the ZSO-doped SBT films will be very beneficial for the low voltage operations in metal-ferroelectric-insulator-Si devices.