Preparation of Bi4Ti3O12 films on a single-crystal sapphire substrate with electron cyclotron resonance plasma sputtering

Abstract

Bi‐Ti‐O oxide thin films were prepared on a sapphire single‐crystal substrate by electron cyclotron resonance (ECR) plasma sputtering. The target used was a sintered Bi₄Ti₃O₁₂(BIT) and the substrate was controlled in the temperature range 400–640 °C(T_sub). The film sputtered at T_sub=400 °C was a pyrochlore type oxide(Bi₂Ti₂O₇), which changed to a Bi₄Ti₃O₁₂ oxide in the polycrystalline state at 500 °C and in the single crystalline state at 640 °C. In the film sputtered at 640 °C, the (001) plane of the Bi₄Ti₃O₁₂ grew parallel to the (112̄0) and (11̄02) planes of the sapphire substrate, and the (104) plane of Bi₄Ti₃O₁₂ grew parallel to the (0001) plane of the sapphire substrate. The deposition rate was about 200 Å/min independent of the sputtering conditions.