Switchable and tunable strontium titanate electrostrictive bulk acoustic wave resonator integrated with a Bragg mirror

Abstract

The realization and the radio-frequency characterization of a tunable strontium titanate (STO) electrostrictive solidly mounted acoustic resonator (SMR) bulk acoustic wave are reported. For a 430nm thick strontium titanate layer, the resonance frequency at 2.2GHz can be switched on with a bias voltage of 6V and tuned ±0.85% with a bias voltage between 6 and 30V. No hysteresis is observed. The SMR tunability is found to be affected by (i) the variation of coupling factor versus bias which is the dominant effect and (ii) the variation of SrTiO3 stiffness at constant electric displacement.