Tunable and high quality factor SrTiO3 surface acoustic wave resonator

Abstract

We fabricated a tunable surface acoustic wave resonator in the 2 GHz-frequency range by depositing and patterning 2 μm-wide pitch inter-digitated Al electrodes on SrTiO3 (STO) paraelectric substrate. We took advantage of the electrostrictive behavior of STO, whose properties are nonlinear with respect to the applied electric field, to induce tunability of the resonance frequency. The obtained frequency tunability reaches 0.7% at 0.5 MV/cm. Besides, the main advantage of this device is its high acoustic quality factor Q reaching 2450 at 2 GHz, thanks to the single-crystal nature of STO. This is one order of magnitude larger than the typical quality factor of its tunable bulk acoustic wave resonators counterparts.