Leakage Current Reduction and Ferroelectric Property of BiFe_1-xCo_xO₃ Thin Films Prepared by Chemical Solution Deposition Using Iterative Rapid Thermal Annealing at Approximately 520 °C

Ferroelectric Bi_1.1Fe_0.9Co_0.1O₃ (BFCO) thin films of 100 nm thickness have been prepared on Pt/TiO₂/SiO₂/Si substrates by chemical solution deposition (CSD) using iterative rapid thermal annealing (RTA) at 510–560 °C. A thin film prepared at 520 °C shows low leakage currents of about 6 ×10^-3 and 2 ×10^-2 A/cm² at 80 K and room temperature (RT) at a high electric field of 2 MV/cm, respectively. However, the leakage current is above 10^-2 A/cm² at high applied electric fields from 1 to 2 MV/cm so that P–E hysteresis loops of the thin film seem to be unsaturated at RT. As a result, the difference in polarizations at the zero field of the BFCO film prepared at 520 °C is 150 µC/cm² at an applied electric field of 3 MV/cm and RT, which is larger than that of 120 µC/cm² at an applied electric field of 4 MV/cm and 80 K.