Tunable bulk acoustic wave resonators based on Ba0.25Sr0.75TiO3 thin films and a HfO2/SiO2 bragg reflector

A switchable and tunable bulk acoustic wave resonator based on a paraelectric phase Ba(0.25)Sr(0.75)TiO(3) thin film and an all-dielectric HfO(2)/SiO(2) Bragg reflector is presented. The achieved tuning range (3.8%) and effective electromechanical coupling coefficient (7.1%) are the highest reported for solidly mounted tunable bulk acoustic wave resonators. The non-conductive Bragg reflector stack provides excellent integration possibilities.