Dielectric Property of Silicate-Doped CaBi₄Ti₄O₁₅ Thin Films

Thin films of silicate-doped CaBi₄Ti₄O₁₅ were fabricated to enhance the insulating property of one-axis-oriented CaBi₄Ti₄O₁₅ films under an applied electric field. The crystalline phase of CaBi₄Ti₄O₁₅, a type of bismuth layer-structured dielectric (BLSD) compound, was successfully grown on (100)LaNiO₃/(111)Pt/TiO₂/(100)Si with the preferential orientation of the (001) plane by the addition of bismuth silicate with a nominal composition of Bi₁₂SiO₂₀ up to 1.00%. The crystallographic orientation of the (001)BLSD plane normal to the substrate surface was degraded by excessive bismuth silicate addition above 1.50%. The breakdown electric field was increased by bismuth silicate addition up to 2.00% without the degraded relative dielectric permittivity (ε_r) of approximately 230. The bismuth silicate could precipitate between the grain boundaries in the CaBi₄Ti₄O₁₅ films without an interface reaction or a solid solution that enhances the insulating behavior of the BLSD films.