Effect of (Zn, Mn) co-doping on the structure and ferroelectric properties of BiFeO3 thin films

BiFe1-2xZnxMnxO3 (BFZMO, with x = 0-0.05) thin films were synthesized via sol-gel method. Effects of (Zn, Mn) co-doping on the structure, ferroelectric, dielectric, and optical properties of BiFeO3 (BFO) films were investigated. BFZMO thin films exhibit rhombohedral structure. Scanning electron microscopy (SEM) images indicate that co-doping leads to a decrease in grain size and number of defects. Leakage current density (4.60 x 10-6 A/ cm2) of BFZMO film with x = 0.02 was found to be two orders of magnitude lower than that of pristine BFO film. Owing to decreased leakage current density, saturated P-E curves were obtained. Maximum double remnant polarization of 413.2 mu C/cm2 was observed for BFZMO thin film with x = 0.02, while that for the BFO film was found to be 199.68 mu C/cm2. The reason for improved ferroelectric properties is partial substitution of Fe ions with Zn and Mn ions, which resulted in a reduction in the effect of oxygen vacancy defects. In addition, co-doping was found to decrease optical bandgap of BFO film, opening several possible routes for novel applications of these (Zn, Mn) co-doped BFO thin films.