Study on distribution of resonance frequency of high-overtone bulk acoustic resonators

Based on the method of characterizing the piezo-films by the distribution of resonance frequency, the factors influencing the distribution of resonance frequency of High-overtone Bulk Acoustic Resonator (HBAR) consisting of a piezoelectric thin film with two electrodes and a substrate are studied. Some HBARs are simulated, the results manifest that changing the acoustic impedance ratio of the substrate to piezo-film the distribution of the space of the parallel resonance frequency and the effective electromechanical coupling factor are changed. When the fundamental mode of the piezo-film is at high frequency, changing the acoustic impedance ratio of the electrode to piezo-film and the thickness of the electrodes make the distribution of the resonance frequency of HBARs changed. These results manifest that the HBARs will be resonant at specific frequencies by the means of adjusting the factors affecting the distribution of the resonance frequency.