Fabrication and electrical properties of Ba0.64Sr0.36TiO3 thin films by sol-gel on platinum coated silicon

Abstract

The Ba0.64Sr0.36TiO3 thin films have been prepared by the sol-gel method on a platinum-coated silicon substrate. The structure and electrical properties of sol-gel derived Barium-strontium-titanate (Ba0.64Sr0.36TiO3) thin films have been investigated. The as-fired thin films are found to be amorphous, and the films crystallize to a perovskite structure after a post deposition annealing at 700°C for 1 h in air. The dielectric constant and dissipation factor for Ba0.64Sr0.36TiO3 thin film at a frequency of 200 Hz were 592 and 0.028, respectively. The temperature dependence of dielectric constant and dissipation factor exhibited a diffused ferroelectric to paraelectric phase transition at 40°C. The ferroelectric nature of this film at room temperature was confirmed by the existence of butterfly-shaped C-V curves caused by switching of the ferroelectric domains. The capacitance changed from 495 to 1108 pF with the applied voltage in the −5 to +5 V range at a frequency of 100 kHz. The pyroelectric coefficient at room temperature (25°C) is 1860 μC/m2K, and the figure-of-merit of this film is 37.4 μC/m3K. The high pyroelectric coefficients and the greater figures of merit of Ba0.64Sr0.36TiO3 thin films make it possible to be used for thermal infra-red detection and imaging.