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Engineering Efficient Acoustic Power Transfer in HBARs and Other Composite Resonators
- Source :
- Journal of Microelectromechanical Systems. 29:1014-1019
- Publication Year :
- 2020
- Publisher :
- Institute of Electrical and Electronics Engineers (IEEE), 2020.
-
Abstract
- We present analytic and experimental evidence highlighting the importance of acoustic impedance matching for efficient power transfer in RF-MEMS composite resonators such as high-overtone bulk acoustic mode resonators (HBARs) and thin-film piezoelectric on substrate (TPoS) resonators. We show that materials used for the piezoelectric film and the bottom metal electrode in a composite resonator can be chosen or tailored for specific low-loss substrates, resulting in efficient acoustic power transmission across the interfaces of the acoustic source (piezoelectric transducer), intermediate layers including the bottom electrode, and into the acoustic cavity (substrate). We find that a composite resonator with good interfacial acoustic matching exhibits characteristic free spectral range (FSR) variations that are not well modeled in the literature, clearly differentiating it from resonators with poor acoustic matching. We verify this model by comparing the FSR spectra of the first experimentally demonstrated epitaxially grown Sc0.18Al0.82N/AlN/TaN/SiC HBARs (with a mismatched TaN bottom electrode) with epitaxial GaN/AlN/NbN/SiC HBARs where all constituent layers are acoustically matched to the substrate. Historically, the choice and quality of materials used for composite resonators has been limited by process constraints, but advances in epitaxial growth and heterogeneous integration techniques allow us to integrate multiple high quality, acoustically matched layers to form multi-functional composite resonators. [2020-0247]
- Subjects :
- 010302 applied physics
Materials science
business.industry
Mechanical Engineering
Composite number
02 engineering and technology
Substrate (electronics)
021001 nanoscience & nanotechnology
Sound power
01 natural sciences
Piezoelectricity
Resonator
0103 physical sciences
Electrode
Optoelectronics
Electrical and Electronic Engineering
0210 nano-technology
Acoustic impedance
business
Free spectral range
Subjects
Details
- ISSN :
- 19410158 and 10577157
- Volume :
- 29
- Database :
- OpenAIRE
- Journal :
- Journal of Microelectromechanical Systems
- Accession number :
- edsair.doi...........fe10a9e40fb64c2298f699a65d032ed0