Structure–properties correlations for barium titanate thin films obtained by rf-sputtering

Abstract

Stoichiometric thin films were deposited by rf-magnetron sputtering from a BaTiO 3 ceramic target on Pd foils used as substrates. Polycrystalline BaTiO 3 films with different grain sizes were obtained by post-deposition heat treatment in air, at 900 °C for 8 h. A multi-step deposition–annealing technique was used in order to improve the compactness and therefore, the dielectric behaviour. The structural characteristics and the surface topography varied obviously with both films thickness and deposition–annealing procedure. X-ray diffraction data pointed out that the so-called “pseudocubic” phase, generally reported for such fine-grained thin films, does not involve only a highly distorted unit cell, but consists obviously, in our case, from a mixture of crystalline phases, with tetragonal and cubic symmetry, respectively. The dielectric properties (relative permittivity and loss tangent) showed small frequency dispersion. The BaTiO 3 film of 0.6 μm thickness obtained by four deposition–annealing cycles exhibited a dielectric constant of ∼700 and a dissipation factor of 0.06 at 100 kHz.