Interface-based reduced coercivity and leakage currents of BiFeO3 thin films: A comparative study

Highlights: • The role of metallic (Pt) and oxide (IrO₂ and LaNiO₃) electrodes on the texture and functional properties of BiFeO₃ films is disclosed. • LaNiO₃ is the most effective in optimizing the electrical properties of BiFeO₃ films due to decreased stress, enhanced texture and crystallinity. • BiFeO₃ films are highly (012) oriented when deposited on non-textured oxide electrodes because of the natural growth habit of BiFeO₃ along this plane. • 400 nm thick BiFeO₃ films on LaNiO₃ possess a large P_r of 50 μC/cm², a small E_c of 150 kV/cm and a low J of ~4 × 10⁻⁶ A/cm² at room temperature. Obtaining high quality BiFeO₃ thin-films by low-cost scalable chemical solution deposition (CSD) is still challenging and currently relevant. Here we provide a comprehensive set of experimental evidences on the role of metallic (Pt) and oxide (IrO₂ and LaNiO₃) electrode interfaces on the texture development and functional properties improvement of CSD-derived BiFeO₃ films. All BiFeO₃ films are composed of columnar grains, which lateral size is dependent on the bottom electrode/interface. Whereas no texture was observed for 320 nm thick films fabricated on (111) oriented Pt, films on oxide electrodes, particularly on non-textured LaNiO₃, are highly (012) oriented. Moreover, 400 nm thick BiFeO₃ films on LaNiO₃ possess a large remanent polarization 50 μC/cm², a small coercive field 150 kV/cm and a low leakage current density ~4 × 10⁻⁶ A/cm² at room temperature. In contrast, BiFeO₃ films on the other electrodes reveal polarization hysteresis with high leakage current that increases with film thickness decrease. We demonstrate that LaNiO₃ interfaces enhance crystallinity and orientation of BiFeO₃ thin-films reflected in optimization of their functional properties. We advocate that besides the need of monophasic films, oxide electrodes and their interfaces have a relevant role on the development of high-quality BiFeO₃ thin-films fabricated by CSD and derived devices.