Effect of Ba and Zr doping in Sr0.8Bi2.2Ta2O9 thin films

The influence of large ion doping in Sr0.8Bi2.2Ta2O9 (SBT) thin films grown on Pt/Ti/Si(1 0 0) substrates was studied from the view point of changing the ferroelectric and dielectric parameters such as remanent polarization (Pr), coercive field (EC) and dielectric constant (εr) by adding 5, 10 and 15 mol% of Ba and Zr relative to constituent Sr and Ta, respectively. Ferroelectric hysteresis loops measured at a frequency of 10 kHz indicated that (2Pr) significantly decreased to approximately 12, 7.6, 1.6 μC/cm2 (compared to 14.4 μC/cm2 of SBT) and (2EC) enhanced to approximately 180, 200 kV/cm and 150 (compared to 145 kV/cm of SBT) and by 5, 10, 15 mol% doping, respectively. Dielectric constants decreased to 135, 115 and 75 (compared to 190 of SBT) by 5, 10, 15 mol% doping, respectively. It is observed that the doping causes a slight increase in the leakage current density but it is still on the order of 10-7 A/cm2 at electric field of 300 kV/cm. Such parameters would make Ba and Zr doped SBT as a candidate ferroelectric-gate in FET memory applications.