Orientation of Bi₄Ti₃O₁₂-based ferroelectric thin films prepared on various kinds of substrates by metalorganic chemical vapor deposition

La- and V-substituted thin films of Bi₄Ti₃O₁₂ (Bi_3.25,La_0.75)(Ti_2.97,V_0.03) O₁₂ (BLTV) were prepared by metalorganic chemical vapor deposition on (1 1 1)Ir/TiO₂/SiO₂/Si, (1 1 1)Pt/TiO₂/SiO₂/Si, and (1 1 1)Pt/Ti/SiO₂/Si substrates at 600°C. Film orientation was investigated by X-ray reciprocal space mapping together with the conventional X-ray 2θ-θ scan. All the films consisted of a single phase of BLTV and showed mainly (0 0 1)- and (1 1 7)-orientations on a 2θ-θ scan. However, it was confirmed that the weak (1 1 7)-, strong (1 0 4)-, and (1 1 1)-centered orientations; (1 1 0), (1 1 1), and (1 1 2) orientations, were ascertained for the films deposited on (1 1 1)Pt/TiO₂/SiO₂/Si, (1 1 1)Pt/Ti/SiO₂/Si, and (1 1 1)Ir/TiO₂/SiO₂/Si substrates, respectively, by the X-ray reciprocal space-mapping measurement. These tendencies were in response to the ferroelectric property of the film. As a result, orientation of the film strongly depended on the kinds of substrates and the X-ray reciprocal space mapping is the useful method to investigate the orientation of the bismuth-layer-structured ferroelectric thin films.