Crystallization of SrBi2Ta2O9 Thin Films in N2 Ambient by Chemical Solution Deposition Method

Structural and electrical properties of SrBi2Ta2O9 (SBT) thin films crystallized upon annealing in an N2 ambient were investigated. These thin films were prepared on Pt/TiO2/SiO2/Si substrates by the chemical solution deposition (CSD) method. The films crystallized in N2 after calcination at a high O2 partial pressure in an N2/O2 mixed ambient showed good ferroelectric properties with remanent polarization 2Pr=13–14 µC/cm2, coercive field 2Ec=70–80 kV/cm, and leakage current density less than 1×10-7 A/cm2 at an applied voltage of 3 V. These ferroelectric properties are the same as those of the SBT crystallized in O2. However, the films crystallized in N2 after calcination at a low O2 partial pressure in an N2/O2 mixed ambient did not form SBT. TDS data showed that the carbon content of the film calcined in poor O2 was higher than that of the film calcined in rich O2. These results showed that the carbon residue within the film might disturb the formation of SBT.