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

Alexandru C. Fechete; Samuel James Ippolito; Kourosh Kalantar-Zadeh; Wojtek Wlodarski; Anthony Stephen Holland

doi:10.1117/12.582076

23 February 2005 Surface acoustic wave based ozone sensor with an InO_x/Si₃N₄/36° YX LiTaO₃ structure

Alexandru C. Fechete, Samuel James Ippolito, Kourosh Kalantar-Zadeh, Wojtek Wlodarski, Anthony Stephen Holland

Proceedings Volume 5650, Micro- and Nanotechnology: Materials, Processes, Packaging, and Systems II; (2005) https://doi.org/10.1117/12.582076
Event: Smart Materials, Nano-, and Micro-Smart Systems, 2004, Sydney, Australia

Abstract

A layered Surface Acoustic Wave (SAW) device based on an InO_x/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 (InO_x) sensing layer was deposited over the Si₃N₄ layer. Both layers were deposited by RF magnetron sputtering. InO_x 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.

Citation Download Citation

Alexandru C. Fechete, Samuel James Ippolito, Kourosh Kalantar-Zadeh, Wojtek Wlodarski, and Anthony Stephen Holland "Surface acoustic wave based ozone sensor with an InO_x/Si₃N₄/36° YX LiTaO₃ structure", Proc. SPIE 5650, Micro- and Nanotechnology: Materials, Processes, Packaging, and Systems II, (23 February 2005); https://doi.org/10.1117/12.582076

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