Comparison of gas sensing properties of spray pyrolysed VO_x thin films

Nanocrystalline vanadium oxide thin films have been deposited on preheated glass substrates by a simple spray pyrolysis method at three deposition times (i.e. 20, 40, 60 min). Their physical properties were studied as a function of the deposition time. The structure of the deposited films was studied by X-ray diffraction and different vanadium oxide phases are found which identified as VO_x. The films microstructures were investigated with atomic force microscopy and field emission scanning electron microscopy. The prepared films have been placed in an electric circuit for the evaluation of gas sensing properties. The results showed a response to ethanol and it was verified that the film growth and gas response were affected by the deposition time. The optimal operating temperature, dynamic response and sensitivity of the vanadium oxide samples have been measured. According to our results, the sensitivity of the samples linearly increased with different concentration of ethanol and the film with the lowest deposition time was found to exhibit the best sensitivity.