dc field and temperature dependent acoustic resonances in parallel-plate capacitors based on SrTiO3 and Ba0.25Sr0.75TiO3 films: Experiment and modeling

Abstract

Experimentally observed resonant absorption peaks in frequency dependent loss tangent in thin film parallel-plate $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ and ${\mathrm{Ba}}_{0.25}{\mathrm{Sr}}_{0.75}\mathrm{Ti}{\mathrm{O}}_3$ capacitors are explained by electrostriction and piezoelectric effects. A simple theory (linear approximation) is proposed to model the electric field and temperature dependences of the acoustic resonant frequencies, and the intensities of the microwave into acoustic transformations. The electric field dependence of the acoustic resonant frequencies may be used to develop tunable thin film bulk acoustic wave resonators (TFBARs) operating at frequencies up to $10\mathrm{GHz}$ and above. The expected tuneability of the TFBARs is more than 5%.