Room Temperature Nanophononics from 1 GHz - 110 GHz with Composite Piezoelectric Transducer HBARs

• Published in: 2024 IEEE 37th International Conference on Micro Electro Mechanical Systems (MEMS) pp. 1087 - 1090
• Main Authors: Gokhale, Vikrant J., Roussos, Jason A., Hardy, Matthew T., Katzer, D. Scott, Downey, Brian P.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 21.01.2024
• Subjects: acoustic phonons; Acoustics; epitaxial thin films; High overtone bulk acoustic resonators; Micromechanical devices; phonon spectroscopy; Piezoelectric transducers; Q-factor; Resonators; scandium aluminum nitride; Spectroscopy; Temperature distribution
• DOI: 10.1109/MEMS58180.2024.10439362

This paper presents epitaxially grown high overtone bulk acoustic resonators (epi-HBARs) demonstrating a dense spectrum of acoustic/phononic cavity overtone modes in an unprecedented range from 1 GHz to 110 GHz in a single device at room temperature. A critical element is the use of the composite structure of the ScAlN/AlN piezoelectric transducer to enable preferential transduction of higher order envelope modes. The strongest modes presented in this work lie in the 35 GHz - 50 GHz envelope, with Bode quality factor (Q Bode ) as high as 1000 (f × Q > 4×10 13 Hz). This extreme embodiment of a multi-mode MEMS resonator can be developed into a platform for phonon spectroscopy and coupled-physics experiments.