Gas sensing characteristics of Fe-doped tungsten oxide thin films (original) (raw)

2012, Sensors and Actuators B: Chemical

This study reports on the gas sensing characteristics of Fe-doped (10 at.%) tungsten oxide thin films of various thicknesses (100-500 nm) prepared by electron beam evaporation. The performance of these films in sensing four gases (H 2 , NH 3 , NO 2 and N 2 O) in the concentration range 2-10,000 ppm at operating temperatures of 150-280 • C has been investigated. The results are compared with the sensing performance of a pure WO 3 film of thickness 300 nm produced by the same method. Doping of the tungsten oxide film with 10 at.% Fe significantly increases the base conductance of the pure film but decreases the gas sensing response. The maximum response measured in this experiment, represented by the relative change in resistance when exposed to a gas, was R/R = 375. This was the response amplitude measured in the presence of 5 ppm NO 2 at an operating temperature of 250 • C using a 400 nm thick WO 3 :Fe film. This value is slightly lower than the corresponding result obtained using the pure WO 3 film ( R/R = 450). However it was noted that the WO 3 :Fe sensor is highly selective to NO 2 , exhibiting a much higher response to NO 2 compared to the other gases. The high performance of the sensors to NO 2 was attributed to the small grain size and high porosity of the films, which was obtained through e-beam evaporation and post-deposition heat treatment of the films at 300 • C for 1 h in air.

Sign up for access to the world's latest research.

checkGet notified about relevant papers

checkSave papers to use in your research

checkJoin the discussion with peers

checkTrack your impact