Significantly improved ferroelectric properties of (Zn,Co) co-doped BiFeO3 thin films prepared by sol-gel method

BiFe1-2xZnxCoxO3 (BFZCO) thin films (x = 0%, 1%, 2%, 3%, 4%, 5%) were deposited on FTO/glass substrates by sol-gel method. We systematically investigated the effects of equal doping of (Zn, Co) on the crystal microstructure, leakage current, leakage mechanism, and ferroelectric properties of BFZCO thin films. The XRD patterns indicate that all samples matched the chalcogenide structure without any impurity phases. The BiFe0.96Zn0.02Co0.02O3 (BFZCO-2) film exhibited a large residual polarization (2Pr = 339.9 μC/cm2) at an electric field strength of approximately 2000 kV/cm. The curve of leakage current density shows that equal doping of (Zn, Co) can considerably decrease the leakage current of BFO thin films at low electric fields. Furthermore, the mechanism of leakage conduction has shifted from Ohmic conduction at low electric fields to SCLC conduction at high electric fields.