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 Bi 4 Ti 3 O 12 thin films was carried out by spin-coating pyrolysis of Bi and Ti naphthenates and successive heat treatment in O 2 gas at various pressures. Heat treatment in O 2 gas at high pressure was effective for the fabrication of c -axis oriented Bi 4 Ti 3 O 12 thin films with a smooth surface and improvement of their electric properties. The thin film heat-treated at the O 2 gas pressure of 4.0×10 5 Pa was a single phase of Bi 4 Ti 3 O 12 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/cm 2 , dielectric constant of 45, loss of 0.01 and leakage current density on the order of 10 -9 A/cm 2 . The remanent polarization of the thin film was kept constant up to the polarization reversal at 1×10 7 cycles.