Comparative study of surface acoustic wave based hydrogen sensors with: InOx/SiNx/36° YX LiTaO3 structure

Alexandru C. Fechete; Wojtek Wlodarski; Kourosh Kalantar-zadeh; Anthony S. Holland; Jarek Antosziewski; Saulius Kaciulis; Luca Pandolfi

doi:10.1117/12.638505

5 January 2006 Comparative study of surface acoustic wave based hydrogen sensors with: InO_x/SiN_x/36° YX LiTaO₃ structure

Alexandru C. Fechete, Wojtek Wlodarski, Kourosh Kalantar-zadeh, Anthony S. Holland, Jarek Antosziewski, Saulius Kaciulis, Luca Pandolfi

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Proceedings Volume 6035, Microelectronics: Design, Technology, and Packaging II; 603517 (2006) https://doi.org/10.1117/12.638505
Event: Microelectronics, MEMS, and Nanotechnology, 2005, Brisbane, Australia

Abstract

Layered Surface Acoustic Wave (SAW) based sensors with: InO_x / SiN_x / 36° YX LiTaO₃ structure were developed for sensing different hydrogen (H₂) concentrations between 0.06% (600ppm) and 1% H₂ in synthetic air. This paper presents a comparative study of the sensors performances in terms of response time, recovery time and response magnitude as a function of operational temperature. The SAW devices consist of metal interdigitated electrodes fabricated on lithium tantalate (LiTaO₃) piezoelectric substrate forming the input and output Interdigital Transducers (IDTs). A 1 μm thick silicon nitride (SiN_x) intermediate layer was deposited over these finger pairs, either by Plasma Enhanced Chemical Vapour Deposition (PECVD) or by r.f. magnetron sputtering. A 100 nm thin film of indium oxide (InO_x) deposited by r.f. magnetron sputtering provides the selectivity towards hydrogen. The highest sensitivity for the sensor with r.f. magnetron sputtered SiN_x intermediate layer was recorded at 190° C, when the frequency shift of 361 KHz for 1% H₂ in synthetic air was recorded. However larger responses were obtained for the sensor with the PECVD SiN_x intermediate layer at 290° C, when the large frequency shift of 516 KHz was recorded for the same H₂ concentration. Microstructural characterization of the InO_x and SiN_x films by Atomic Force Microscopy (AFM) and X-Ray Photoelectron Spectroscopy (XPS) is also presented.

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Alexandru C. Fechete, Wojtek Wlodarski, Kourosh Kalantar-zadeh, Anthony S. Holland, Jarek Antosziewski, Saulius Kaciulis, and Luca Pandolfi "Comparative study of surface acoustic wave based hydrogen sensors with: InO_x/SiN_x/36° YX LiTaO₃ structure", Proc. SPIE 6035, Microelectronics: Design, Technology, and Packaging II, 603517 (5 January 2006); https://doi.org/10.1117/12.638505

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KEYWORDS

Sensors

Indium oxide

Plasma enhanced chemical vapor deposition

Magnetic sensors

Sputter deposition

Hydrogen

Thin films

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