| Effect of grain orientation on the electrical polarization and leakage current characteristics of Bi_(3.25)La_(0.75)Ti₃O_(12) (BLT) thin films was investigated in terms of c-axis off alignment. The c-axis epitaxial and various c-axis off aligned BLT films have been successfully grown by using different electrode materials (Pt and SrRuO₃) and heat-treatments. In order to evaluate the crystallinity and the film texture of various c-axis off-aligned BLT thin films, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were carried out. BLT thin film grown on the SrRuO₃/SrTiO₃ (100) substrate revealed that its c-axis aligned completely parallel to the substrate normal, by developing cube-on-cube epitaxial relathionship with underlying SrRuO₃ film. The corresponding P-E curve showed nearly paraelectric property. The polycrystalline (117) and (014) oriented BLT films grown in this study were shown that their c-axis off alignment about growth direction increased by amount more than 50°. As the degree of c-axis off-alignment was increased, remanent polarization was increased due to the anisotropic polarization characteristic of BLT film, however, the surface roughness of BLT films was increased and it resulted in degraded leakage current characteristic. Therefore, grain orientation of BLT thin films is a crucial factor controlling the polarization properties and leakage current characteristics. |
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