Connection between physical response of porous alumina sensors and their morphology

Al2O3 porous films have been obtained by anodization of sputtered Al thin films with the aim of preparing capacitive humidity sensors operating at low temperatures (up to -60 degrees C) and low humidity contents (from 5 ppmv up to 50 ppmv). The response in this range of humidity was the fundamental point of our work: in fact, alumina sensors are generally used for ambient humidity with RK from few percent to 100%. The electrical response of the sensor has been linked to the morphology of the alumina layer. Et was verified that it is necessary to differentiate the anodization process, to change the porous structure of the sensitive layer as far as mean dimensions and pore densities are concerned. We have demonstrated the possibility to obtain sensitive devices.