Nickel oxide thin film sensor for fluctuation-enhanced gas sensing of formaldehyde

Nanocrystalline nickel-oxide-based thin films were prepared by advanced reactive gas deposition, and the response of these films to formaldehyde was studied by fluctuation-enhanced sensing. Morphological and structural analyses showed porous deposits of nickel oxide particles with face-centered cubic structure. Resistance fluctuations were measured upon exposure to ethanol, formaldehyde and methane at 200 °C. Power density spectra were used to quantify the response. The response to formaldehyde was higher than to ethanol at 200 °C, and no significant response was observed for methane thus demonstrating some gas-species selectivity.