Preparation and characterization of highly c-axis-oriented Bi₄Ti₃O₁₂ thin films

Highly c-axis-oriented bismuth titanate (Bi₄Ti₃O₁₂) thin films were prepared on (100)-oriented silicon wafers by rf planar magnetron sputtering using a target of Bi₂TiO₅ ceramic at a low substrate temperature of 600°C. The films with a c-axis orientation up to 99% were obtained under high deposition rate approximately 1.1 μm h ¹. Dielectric constant of these films were dependence of film thickness. This behavior was explained assuming a low-dielectric-constant interface layer. Using this assumption, the dielectric constant of Bi₄Ti₃O₁₂ film was estimated to be approximately 140. This value is similar to that along the c-axis in a bulk form. A D E hysteresis characteristic has been observed at room temperature. The remanent polarization and the coercive field are 0.8 μC cm ² and 20 k V cm ¹, respectively. From analysis of refractive index, interface layer was confirmed an oxidized silicon, which was formed before and/or during film deposition.