Gas sensor microsystems based on nanostructured layers via anodic oxidation

Identifier:  TDX:1130

Handle: https://hdl.handle.net/20.500.11797/TDX1130

Authors:  Calavia Boldú, Raúl

Abstract:
This thesis shows the methodology to obtain nanostructured tungsten oxide layer as sensing material on silicon micromachined gas sensor devices. A porous anodised alumina layer was used as pattern to obtain it, so a technique has been developed to make compatible the anodising of aluminium and other metals like tungsten with the standard silicon processes. Two different nanostructuring approaches were developed, nanotube and nanodot based tungsten oxide layers. The WO3 nanotube layer has been obtained by the tungsten oxide deposition using reactive sputtering on the porous alumina layer. As a result a continuous sensing layer coats the pores without clogging them. WO3 nanodot layers were obtained by the anodising of an aluminium and tungsten bilayer, where the first anodising process grows the porous alumina layer and the second one generates the tungsten oxide nanodots in the end of the pores. Compositional and morphological studies and the study of their behaviour as gas sensors where conducted for the two nanomaterials. The results have been compared with the flat tungsten oxide layers on micromachined gas sensors.