Film Thickness Dependence of Dielectric Properties of BaTiO3 Thin Films Prepared by Sol-Gel Method

Abstract

Ferroelectric BaTiO₃ thin films were prepared on Pt(111)/ SiO₂/Si(100) substrates at 650° C by the sol-gel method. Film thickness could be varied by repeating a dip coating/heating cycle. The texture of the BaTiO₃ thin films became more dense and homogeneous when the film thickness increased. The crystalline thin films showed microstructure with grains as small as 20–30 nm. The dielectric properties could be measured for films thicker than 0.25 µ m. With increasing film thickness, the dielectric constant and remanent polarization increased and the coercive field decreased. Loss tangent of the thin films was independent of the film thickness. BaTiO₃ thin film with a thickness of 0.58 µ m exhibited a dielectric constant of 1000, remanent polarization of 8 µ C/cm² and coercive field of 30 kV/cm.