Abstract
Transmission electron microscopy (TEM) observation was used to study a polycrystalline BiFeO3 film fabricated by a chemical solution deposition (CSD) on Pt/Ti/SiO2/Si(l00) substrates. Cross-sectional TEM images and corresponding selected area diffraction patterns (SAED) as well as x-ray diffraction (XRD) patterns indicated that the polycrystalline single phase of the BiFeO3 film was formed after annealing at 823 K for 10 min. Interfacial structural analysis making use of a high resolution cross-sectional TEM observation showed that a 1-2-nm-thick amorphous layer was formed only at the interface of the bottom electrode, and we found this amorphous layer deteriorates the leakage current quality. Ferroelectric hysteresis loops were measured by using a high frequency of 100 kHz system in order to suppress the leakage current component. The remanent polarization and the electrical coercive field of the BiFeO3 film were around 46 micro C/cm2 and 230 kV/cm, respectively at room temperature. At 10 K, the remanent magnetization and a magnetic coercivity were around 2 emu/cm3 and 0.5 kOe, respectively. However each parameter disappears at least 40 K. A broad peak was observed at 70 K in zero-field-cooling curve, which indicates a spin glass behavior of the BiFeO3 film.
