HBAR resonator comprising a structure for amplifying the amplitude of at least one resonance of said resonator and methods for producing such a resonator

A HBAR resonator, comprising an amplification structure wherein the amplification structure comprises:

• on a substrate, a piezoelectric transducer, said transducer comprising at least one piezoelectric layer and at least two electrodes and exhibiting resonance frequencies Fi corresponding to wavelengths λi;
• and
• at least one resonant cavity arranged on the substrate between said transducer and said substrate or in said substrate, this amplification structure being suitable for mechanically resonating at at least one of the resonance frequencies Fi of said transducer corresponding to said wavelength λi, so as to amplify the amplitude of the electrical resonance generated at said frequency,
• wherein the resonant cavity is defined as being a single-layer or multilayer structure exhibiting an acoustic transmission spectrum characterized by relatively low levels, being able to be 0.5 or less, and over a wider frequency range bracketing the working frequencies Fi, but with localized transmission peaks at the frequency Fi of interest.