Tunable Optical and Multiferroic Properties of Zirconium and Dysprosium Substituted Bismuth Ferrite Thin Films

This work presents optical and multiferroic properties of bismuth ferrite thin films that are affected by zirconium and dysprosium substitution. Non-centrosymmetric BiFeO₃,Bi_0.95Zr_0.05FeO₃, and Bi_0.95Dy_0.05FeO₃ thin films were coated on Pt/TiO₂/SiO₂/Si substrates using the spin coating method. The crystal structure, optical properties, microstructural, ferromagnetic, and ferroelectric properties of doped bismuth ferrite thin films were systematically investigated. From the XRD patterns, all the prepared thin films matched well with the rhombohedral structure with R3c space group with no observed impurity phases. The average crystallite size of the bismuth ferrite thin films were between 35 and 47 nm, and the size depended on the type of dopant. The determined energy band gap values of BiFeO₃, Bi_0.95Dy_0.05FeO₃, and Bi_0.95Zr_0.05FeO₃ thin films were 2.32 eV, 2.3 eV, and 2 eV, respectively. Doping of Dy and Zr at the Bi site led to reduced surface roughness. The prepared thin films exhibited enhanced ferromagnetic and ferroelectric properties. The remnant magnetization of Zr-doped BiFeO₃ was greater than that of the BiFeO₃ and Dy-doped BiFeO₃ thin films. From the obtained results, it was concluded that Zr-doped BiFeO₃ thin films are suitable for solar cell fabrication.