Ethanol Sensitivity of Thermally Evaporated Nanostructured WO<sub>3</sub> Thin Films Doped and Implanted with Fe

Abstract

Ethanol sensing performance of gas sensors made of Fe doped and Fe implanted nanostructured WO3thin films prepared by a thermal evaporation technique was investigated. Three different types of nanostructured thin films, namely, pure WO3thin films, iron-doped WO3thin films by co-evaporation and Fe-implanted WO3thin films have been synthesized. All the thin films have a film thickness of 300 nm. The physical, chemical and electronic properties of these films have been optimized by annealing heat treatment at 300oC and 400oC for 2 hours in air. Various analytical techniques were employed to characterize these films. Atomic Force Microscopy and Transmission Electron Microscopy revealed a very small grain size of the order 5-10 nm in as-deposited WO3films, and annealing at 300oC or 400oC did not result in any significant change in grain size. This study has demonstrated enhanced sensing properties of WO3thin film sensors towards ethanol at lower operating temperature, which was achieved by optimizing the physical, chemical and electronic properties of the WO3film through Fe doping and annealing.