Estimation of leakage current density and remanent polarization of BiFeO3 films with low resistivity by positive, up, negative, and down measurements

Polycrystalline BiFeO₃ film was fabricated by chemical solution deposition (CSD) on 111-textured Pt/Ti/SiO₂/Si(100) substrates followed by post-annealing at 923K in air. The leakage current density was estimated by pulse response of a positive, up, negative, and down (PUND) measurement. It was revealed that the leakage current density estimated by PUND measurements is useful for high leakage current materials because the dielectric breakdown could be extended to the high electric field region when compared to a conventional measurement way using a pico-ampere meter. Therefore, the changing point of the leakage current mechanism at the higher electric field of 0.3 MV/cm could be observed by using the PUND method in the present specimen. When the temperature was decreased, it was revealed that the leakage current component did not affect the ferroelectric polarization below 150 K in the case of present specimen. At 93 K, where leakage current was suppressed, the remanent polarizations were evaluated by ferroelectric hysteresis loops and PUND, and it was revealed that the remanent polarization did not saturate until an electric field of 1.4 MV/cm was applied (P_r = 89 μC/cm₂ at P-E loop, 2P_r = 164μC/cm² at PUND). This result indicates the potential of BiFeO₃ to have quite high remanent polarization.