Fig. 3 shows the surface morphology and the cross-sectional micrograph of the BCO/BFO double-layered thin film. In Fig. 3 the thin film can be seen to have 17-ODYA dense surface without any cracks and an average grain size of about 90 nm. The thickness of the BCO/BFO film (160 nm) was estimated from the cross-sectional SEM micrograph.
Fig. 3. Surface morphology and cross-sectional micrograph of the BCO/BFO double-layered thin film.Figure optionsDownload full-size imageDownload as PowerPoint slide
The dielectric properties of the BCO/BFO double-layered thin film were investigated at room temperature and the results are shown in Fig. 4. The frequency dependence of the dielectric constant (ε) and dielectric loss (tanδ) of the thin film were found to be 75 and 0.042, respectively, and were measured at frequencies ranging from 100 Hz to 1 MHz. The observed reduction in the dielectric constant in the high frequency region is attributed to the reduced contribution of space charge polarization resulting from the presence of the BCO layer , and suggests a lower oxygen vacancy concentration in the double-layered thin film.