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

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.