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Proceedings Paper

Surface acoustic wave based ozone sensor with an InOx/Si3N4/36-degree YX LiTaO3 structure
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Paper Abstract

A layered Surface Acoustic Wave (SAW) device based on an InOx/Si3N4/36° YX LiTaO3 structure is investigated for sensing ozone in air at different operating temperatures and concentrations. These concentrations are between 25 ppb and 150 ppb. Layered SAW devices are of a great interest as they show a remarkable performance for liquid and gas sensing applications. This structure is a single delay line SAW device with 64 input and output finger pairs, having periodicity of 24 μm. They were fabricated on a 36° Y-cut X-propagating lithium tantalate (LiTaO3) piezoelectric substrate. A 1 μm thick silicon nitride (Si3N4) layer was deposited over the finger pairs and a 100 nm indium oxide (InOx) sensing layer was deposited over the Si3N4 layer. Both layers were deposited by RF magnetron sputtering. InOx was chosen as it has a remarkable sensitivity towards ozone. Si3N4 was chosen as it is inert and has stable characteristics at high temperature. The sensor performance is analysed in terms of response time, recovery time and response magnitude as a function of operational temperature. The operational temperature ranges between 185°C and 205°C. The sensor shows repeatability, reversibility, fast response and recovery time. At approximately 190°C the highest sensitivity was observed. A frequency shift of 5.0 kHz at 25 ppb, 6.5 kHz at 50 ppb ozone was recorded. The presented results show this structure is promising for gas sensing applications.

Paper Details

Date Published: 23 February 2005
PDF: 8 pages
Proc. SPIE 5650, Micro- and Nanotechnology: Materials, Processes, Packaging, and Systems II, (23 February 2005); doi: 10.1117/12.582076
Show Author Affiliations
Alexandru C. Fechete, RMIT Univ. (Australia)
CRC for microTechnology (Australia)
Samuel James Ippolito, RMIT Univ. (Australia)
CRC for microTechnology (Australia)
Kourosh Kalantar-Zadeh, RMIT Univ. (Australia)
CRC for microTechnology (Australia)
Wojtek Wlodarski, RMIT Univ. (Australia)
CRC for microTechnology (Australia)
Anthony Stephen Holland, RMIT Univ. (Australia)

Published in SPIE Proceedings Vol. 5650:
Micro- and Nanotechnology: Materials, Processes, Packaging, and Systems II
Jung-Chih Chiao; David N. Jamieson; Lorenzo Faraone; Andrew S. Dzurak, Editor(s)

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