Skip to content Home Contact Mobile MyRMIT Library A-Z
RMIT UniversityResearch Repository
 

Layered surface acoustic wave based gas sensors utilising nanostructured indium oxide thin layer

Fechete, A 2009, Layered surface acoustic wave based gas sensors utilising nanostructured indium oxide thin layer, PhD Thesis, School of Electrical and Computer Engineering, RMIT University.

Document type: Thesis
Collection: Theses
Attached Files
Name Description MIMEType Size Downloads
Fechete.pdf Thesis application/pdf 4.13MB 299

Title Layered surface acoustic wave based gas sensors utilising nanostructured indium oxide thin layer
Author(s) Fechete, A
Year 2009
Abstract Planar two-dimensional (2-D) nanostructured indium oxide (InOx) and one-dimensional (1-D) tin oxide (SnO2) semiconductor metal-oxide layers have been utilised for gas sensing applications. Novel layered Surface Acoustic Wave (SAW) based sensors were developed consisting of InOx/SiOxNy/36°YXLiTaO3, InOx/SiNx/SiO2/36°YXLiTaO3 and InOx/SiNx/36°YXLiTaO3 The 1 µm intermediate layers of silicon oxynitride (SiOxNy), silicon nitride (SiNx) and SiO2/SiNx matrix were deposited on lithium tantalate (36°YXLiTaO3) substrates by r.f. magnetron sputtering, electron-beam evaporation and plasma enhanced chemical vapour deposition (PECVD) techniques, respectively. As a gas sensitive layer, a 100 nm thin layer of InOx was deposited on the intermediate layers by r.f. magnetron sputtering. The targeted gases were ozone (O3) and hydrogen (H2). An intermediate layer has multiple functions: protective role for the interdigital transducers' electrodes as well as an isolating effect from InOx sensing layer, thereby improving the sensor performance. The developed SAW sensors' exhibited high response magnitudes with repeatable, reversible and stable responses towards O3 and H2. They are capable of sensing concentrations as low as 20 parts-per-billion for O3 and 600 parts-per-million for H2. Additionally a conductometric type novel sensing structure of SnO2/36°YX LiTaO3 was also developed by depositing a thin layer of SnO2 nanorods by PECVD. The gas sensing performance exhibited repeatable, reversible, stable responses towards NO2 and CO. The surface morphology, crystalline structure and preferred orientation of the deposited layers were investigated by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). A polycrystalline, oxygen deficient non-stoichiometric InOx with grain sizes of 20-40 nm was revealed. The 1-D nanostructures were characterised by Transmission Elect ron Microscopy (TEM) showing nanorods with needle-like shape , diameters of 10-20 nm at the top and 30-40 nm at the base as well as a preferential growth orientation of [ ] on the LiTaO3 substrate. The developed sensors are promising for O3, H2 and CO sensing.
Degree PhD Thesis
Institution RMIT University
School, Department or Centre School of Electrical and Computer Engineering
Keyword(s) Nanostructured materials -- Design
 
Versions
Version Filter Type
Access Statistics: 79 Abstract Views, 299 File Downloads  -  Detailed Statistics
Created: Mon, 29 Nov 2010, 16:09:00 EST by Catalyst Administrator