P-type semiconducting copper oxide (CuO) thin films deposited by radio-frequency (RF) sputtering were integrated onto microsensors using classical photolithography technologies. The integration of the 50-nm-thick layer could be successfully carried out using the lift-off process. The microsensors were tested with variable thermal sequences under carbon monoxide (CO), ammonia (NH3), acetaldehyde (C2H4O), and nitrogen dioxide (NO2) which are among the main pollutant gases measured by metal-oxide (MOS) gas sensors for air quality control systems in automotive cabins. Because the microheaters were designed on a membrane, it was then possible to generate very rapid temperature variations (from room temperature to 550 °C in only 50 ms) and a rapid temperature cycling mode could be applied. This measurement mode allowed a significant improvement of the sensor response under 2 and 5 ppm of acetaldehyde.

International audiencePromising results on the behavior of CuO/CuFe2O4sputtered thin films as a sensing material under carbondioxide atmospheres are presented in this article. More specifically, we report the effects of preparationparameters and microstructure of the sensing layer on the response to CO2. FEG-SEM images and XPSmeasurements revealed the two-stacked layers rearrangement of samples after air annealing as a keyparameter in gas sensing test. The influence of the sensing layer thickness and the influence of Ag as anadditive in the film on the response are also reported. The best response was obtained at the optimaloperating temperature of 250◦C with a thin film deposited under low argon pressure and low target-to-substrate distance, reaching 40% towards 5000 ppm of CO2