Effects of O2 Gas Pressure in Heat Treatment on Surface Morphology and Electric Properties of Ferroelectric Bi4Ti3O12 Thin Films with c-Axis Orientation

Abstract

Fabrication of ferroelectric Bi₄Ti₃O₁₂ thin films was carried out by spin-coating pyrolysis of Bi and Ti naphthenates and successive heat treatment in O₂ gas at various pressures. Heat treatment in O₂ gas at high pressure was effective for the fabrication of c-axis oriented Bi₄Ti₃O₁₂ thin films with a smooth surface and improvement of their electric properties. The thin film heat-treated at the O₂ gas pressure of 4.0×10⁵ Pa was a single phase of Bi₄Ti₃O₁₂ completely oriented along the c-axis with good ferroelectric properties at room temperature: coercive field of 23 kV/cm, remanent polarization of 1.9 µ C/cm², dielectric constant of 45, loss of 0.01 and leakage current density on the order of 10^-9 A/cm². The remanent polarization of the thin film was kept constant up to the polarization reversal at 1×10⁷ cycles.