Dielectric properties of sol-gel derived barium-strontium titanate (Ba0.4Sr0.6TiO3) thin film

The structural and electrical properties of sol-gel derived barium-strontium-titanate (Ba_0.4Sr_0.6TiO₃ ) thin films have been investigated. The as-fired films are found to be amorphous, and the films crystallize to cubic phase only after a post deposition annealing at 700°C for one hour in air. The measured room temperature dielectric constant (ε´) of the film was about 320. The dielectric constant did not show any significant frequency dependence up to 100 kHz. The temperature dependence of dielectric constant exhibited a diffused a ferroelectric to paraelectric phase transition at -60°C. The room temperature dielectric constant and magnitude of the dielectric peak at the Curie point is found to be dependent on the thickness of the film. The obtained dielectric data on sol-gel barium strontium titanate thin films on platinized silicon substrates has been analyzed in the light of a barrier layer model