Ferroelectric properties and leakage current mechanisms of Bi3.25La0.75Ti3O12 thin films with a-axis preferred orientation prepared by sol–gel method

Abstract

The Bi3.25La0.75Ti3O12 (BLT) thin films were prepared on the Pt/Ti/SiO2/Si substrates using the sol–gel process and crystallized subsequently using the conventional (CTA) and rapid thermal annealing (RTA) processes. It was found that the crystalline, structure, ferroelectric and leakage current properties of BLT films strongly depend upon the heating rate of the sol–gel method. BLT thin films crystallized by the RTA method showed a-axis preferred orientation with smaller grain size comparable with those of films crystallized by the CTA process. The values of remanent polarization (2Pr) and the coercive field (2Ec) of film crystallized by the RTA process were 49 μC/cm2 and 105 kV/cm, respectively. This 2Pr value was larger than that of CTA-derived film (2Pr and 2Ec values were 36 μC/cm2 and 125 kV/cm, respectively). The RTA-derived film had a lower leakage current (4.85×10−8 A/cm2) than the latter (6.5×10−8 A/cm2) at 200 kV/cm, and both films demonstrated fatigue-free behavior up to 108 switching cycles.