RF sputtered and sol-gel prepared MoO/sub 3/-TiO/sub 2/ thin film gas sensors

Abstract

MoO/sub 3/-TiO/sub 2/ thin films have been prepared by RF sputtering (RF) and by the sol-gel (SG) method. The films were deposited on alumina and single crystal silicon substrates. SEM characterization has shown the formation of a well-developed crystal stucture for the SG film and a porous morphology for the RF when annealed at 800/spl deg/C. The MoO/sub 3/-TiO/sub 2/ thin films gas sensing properties to NO/sub 2/ and CO has been investigated. The RF and SG fabricated MoO/sub 3/-TiO/sub 2/ possess different gas sensing properties attributed to the fabrication and resulting morphological difference of the thin films. The SG films had a response of 1.75 to 25 ppm of CO and 2.8 to 2 ppm of NO/sub 2/, while the RF films had a response of 1.5 to 30 ppm of CO and a response of 2 to 3 ppm of NO/sub 2/.