Valence-driven electrical behavior of manganese-modified bismuth ferrite thin films

Abstract

BiFe0.95R0.05O3 (Mn2+, Mn3+, and Mn4+) thin films with (110) orientation were fabricated on SrRuO3/Pt/TiO2/SiO2/Si(100) substrates via rf sputtering. With the increasing valence of Mn in BiFe0.95R0.05O3, the concentration of Fe2+ increases, whereas the concentration of oxygen vacancies decreases. The electrical properties of BiFe0.95R0.05O3 are correlated with the valence of Mn. Their leakage current density is dependent on the concentration of oxygen vacancies caused by different valences of Mn. Their P-E loops become better with the increasing valence of Mn owing to a lower leakage current density in high electric field regions, and a large remanent polarization of 2Pr ∼ 145.2 μC/cm2 is obtained for the Mn4+-doped film. For the Mn2+-doped bismuth ferrite film, the space-charge-limited conduction and Schottky barrier dominate its leakage behavior under a negative electric field, the Ohmic conduction and Schottky barrier are involved in the leakage behavior under a positive electric field, and the interface-limited Fowler–Nordheim tunneling is their dominant mechanism in a high electric field region. In contrast, an Ohmic conduction dominates the leakage behavior of Mn3+- and Mn4+-doped films regardless of negative and positive directions or measurement temperatures.