Fabrication of Bi₄Ti₃O₁₂ films on Pt substrates by inkjet printing

Ferroelectric Bi₄Ti₃O₁₂ thin films were prepared on Pt-coated Si wafers by using alcoholic solutions which dissolved Bi(OtC₅H₁₁)₃ and Ti[OCH(CH₃) ₄] in C₂H₅OC₂H₄OH. To fabricate films with a single phase of the perovskite structure, we fired the precursor films in an atmosphere with strong oxidizability. The fabricated films exhibited a single perovskite phase and a predominantly c-axis orientation with plate-like grains larger than 4 × 4 μm² and smooth surface over an extensive area. The leakage current density of the films was of the order of 10^-7 A/cm². Several 1 × 1 cm² square patterns were directly drawn on a 4-inch Si wafers by inkjet printing (IJP). The minimum dot size realized was approximately 70 μm in diameter. Beside, the force a droplet from printer head was faithfully. However, from the typical thickness profile of the printed line shape patterns, the height at the center of the line was very low while that at the periphery was extremely high. This seems to be due to the surface tension.