Effects of annealing in Ar gas on ferroelectric properties of SrBi2Ta2O9 thin films

The effects of annealing processes at 700 degrees C in Ar gas, added prior to the oxidizing processes of SrBi2Ta2O9 (SBT) films at the lowered temperature of 700 degrees C, are investigated in terms of the ferroelectric properties of the films. SET films 200 nm thick were spin-coated on Pt(200 nm)/Ti(30 nm)/SiO2(200 nm)/Si substrates by using the chemical liquid deposition method. The annealing was found to be effective in obtaining a large saturated polarization and a remanent polarization 2P(r) of more than 10 mu C/cm(2) with leakage current less than 1 x 10(-6) A/cm(2) at the process temperature of 700 degrees C. Structural and compositional analyses suggest that some Bi atoms in the films become free of oxygen and arrive at the lattice sites as a result of the annealing in non-oxidizing Ar gas for periods shorter than 100 s. Consequently, the crystallization of SET layered structures may be promoted even at temperatures as low as 700 degrees C.