Nanostructured copper oxides as ethanol vapour sensors

We report on ethanol (C2H5OH) vapour sensing devices based on nanostructured cupric oxide (CuO) and cuprous oxide (Cu2O) thin films, which are deposited using RF sputtering at relatively low temperature and power conditions: at 120 °C, single stoichiometry CuO and Cu2O films are deposited using the sputtering power of 200 and 250 W, respectively. At such sputtering conditions CuO films exhibit smaller nanocrystallite base dimensions (∼30 nm), in comparison to Cu2O films (∼85 nm), which significantly enhance surface area to volume ratio. Both nanostructured CuO and Cu2O gas sensors are able to detect ethanol vapour as low as several ppm and at relatively low operating temperatures of 180 and 260 °C, respectively. The sensors showed high sensitivity and repeatability, as well as fast response and recovery towards ethanol vapour.