Prominent ferroelectric properties in Mn-doped BiFeO3 spin-coated thin films

Highlights: • Low oxygen vacancy content result in a small leakage current density. • BiFe_0.96Mn_0.04O₃ thin film displays real and excellent ferroelectric property with 2P_r = 311.5 μC/cm². • The band gap of BFMO films increases and the absorption ranges of visible light increases. -- Abstract: BiFe_1-xMn_xO₃ (BFMO, x = 0–0.05) thin films were successfully deposited onto fluorine-doped tin oxide (FTO)/glass substrates via sol–gel technique. According to results obtained from XRD, Raman spectroscopy, SEM, and energy-dispersive EDS, it was found that films have rhomboid perovskite structure and Mn ions were successfully and uniformly incorporated into BiFeO₃ (BFO) films. Doping process was accompanied by the reduction in grain size. From XPS pattern, it was found that both Fe²⁺ concentration and oxygen vacancies are reduced as a result of Mn doping. Compared with pure BFO samples, ferroelectric, dielectric, and optical properties of BFMO films are noticeably enhanced. BiFe_0.96Mn_0.04O₃ film exhibited excellent remnant polarization (2P_r of 312 μC/cm²) accompanied by a low leakage current. Underlying mechanism can be explained in terms of Mn doping-induced structural transition, reduction in grain size, and oxygen vacancies. Additionally, increased bandgap (E_g = 2.68 eV) was obtained in BiFe_0.98Mn_0.02O₃ film compared with BFO film (E_g = 2.58 eV). This work demonstrates remarkable effect of Mn doping on BFO, indicating that BFMO is promising candidate for ferroelectric photovoltaic device applications.