Ferroelectric and electrical properties of BaZrO3 doped Sr0.8Bi2.2Ta2O9 thin films

For the first time, BaZrO3 (BZO) doped Sr0.8Bi2.2Ta2O9 (SBT) thin films were prepared and related ferroelectric and electrical properties were evaluated. Sol-gel thin films of SBT doped with two different BZO mol% ratios were fabricated by spin coating technique on Pt(100nm)/Ti(50nm)/Si(100) substrates. The films were well crystallized at 750 degrees C in oxygen gas by RTA for 30 min. From the XRD analysis the crystalline orientation pattern showed that the dominant orientation is (115) for both doped and pure SBT. The films with 5 and 7 mol% BZO ratios showed ferroelectric hysteresis loops at a frequency of 10 kHz. The remanent polarization (2Pr) was significantly reduced to similar to 5.7 mu C/cm(2) and 1.9 mu C/cm(2) by 5 and 7 mol% doping, respectively. Such a low remanent polarization of 7 mol% BZO doped SBT is suitable for 1T (One Transistor)-FET (Field Effect Transistor) type FeRAMs. The dielectric constant decreased to similar to 135 by 7 mol% doping compare to that of 205 of SBT. Doping leads to an increase in leakage current to 10(-7) A/cm(2) level at electric field at 300 kV/cm.