Ferroelectric properties of lanthanum and praseodymium doped bismuth titanate thin films

Ferroelectric thin films have received considerable attention recently due to their potential applications in the nonvolatile random access memory. Bi-layered ferroelectrics materials such as Bi$_{3.25}$La$_{0.75}$Ti$_{3}$O$_{12}$ (BLT) and SrBi$_{2}$Ta$_{2}$O$_{9}$ are particularly attractive for such applications due to their lower operating voltage and improved fatigue behavior compared to lead zirconium titanate. We have used a chemical solution deposition technique to grow thin films of BLT and Bi$_{4-x}$Pr$_{x}$Ti$_{3}$O$_{12}$ (BPT) on Pt/Si substrates with and without conductive LaNiO$_{3}$ layer. The remanent polarization (2$P_{r})$ of BLT film on Pt/Si, under an applied field of 396 kV/cm, was found to increase from 26 \textit{$\mu $}C/cm$^{2}$ to 43.14 \textit{$\mu $}C/cm$^{2}$ if the BLT film was deposited on LaNiO$_{3}$/Pt/Si substrate. Importantly, BLT films on LaNiO$_{3}$/Pt/Si showed no degradation in the switchable polarization ($P_{sw}-P_{ns})$ after 10$^{10}$ switching cycles. Ferroelectric and leakage current characteristics of BLT and BPT will be discussed as well in this presentation.