Title

Porous Silicon As An Acoustic Material For Baw

Keywords

acoustic impedance; acoustic velocity; BAW

Abstract

Layers of porous silicon with a varying degree of porosity between 30% and 75% were prepared by electro-chemical etching from bulk-Si. Thickness of the layers was in a range of 2 to 4 μm. Acoustic impedance and velocity for longitudinal waves in a frequency range of 2GHz were evaluated utilizing a BAW resonator built on top of the porous Si layers. Material parameters were extracted from the electrical impedance characteristics of the BAW resonators. Special pre-processing of the frequency dependent impedance data was applied to simplify an initial fit to a Mason-Model. A subsequent fit to full data was performed to refine acoustic material parameters and estimate the propagation loss occurring in the porous Si. TEM cross-sections were prepared to verify the thickness of the porous Si layers. The longitudinal acoustic impedance was found to be in the range between 4.6 and 11.1 Mrayl while velocity was 4900 to 6950 m/s. Propagation loss was found to be lower than one would expect from a porous film. © 2012 IEEE.

Publication Date

12-1-2012

Publication Title

IEEE International Ultrasonics Symposium, IUS

Number of Pages

2214-2217

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.1109/ULTSYM.2012.0553

Socpus ID

84882291199 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84882291199

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