Conductometric Gas Sensors based on Nanostructured WO3 Thin Films

Abstract

Nanostructured WO3 thin films have been prepared by
thermal evaporation to detect hydrogen at low temperatures.
The influence of heat treatment on the physical, chemical and
electronic properties of these films has been investigated. The
films were annealed at 400oC for 2 hours in air. AFM and TEM
analysis revealed that the as-deposited WO3 film is high
amorphous and made up of cluster of particles. Annealing at
400oC for 2 hours in air resulted in very fine grain size of the
order of 5 nm and porous structure. GIXRD and Raman analysis
revealed that annealing improved the crystallinity of WO3 film.
Gas sensors based on annealed WO3 films have shown a high
response towards various concentrations (10-10000 ppm) H2 at
an operating temperature of 150oC. The improved sensing
performance at low operating temperature is due to the optimum
physical, chemical and electronic properties achieved in the WO3
film through annealing.