Investigation of a sensitive, selective and cost-effective electrochemical meso-porous silicon based gas sensor for NO2 detection at room temperature

This work presents a nitrogen dioxide (NO2) gas sensor based on porous silicon with improved sensitivity, selectivity, and cost-efficiency. Porous silicon is being researched as an alternative material for gas sensors operating at room temperature (RT), making it suited for low-consumption applications. Meso-porous silicon (meso-PS) films were prepared on p+ type Si (100) using an electrochemical method for NO(2 )gas sensing. Morphology, structural and optical properties of meso-PS films were investigated using scanning electron microscope (SEM), X-ray diffractometer (XRD), and UV-Vis spectroscopy. The gas sensing response of meso-PS samples was performed at RT with top parallel Al electrodes in the range of 4-10 ppm of NO2 gas. The tested sensor showed high normalized response (Rair/Rgas = 40 for 4 ppm to 100 for 10 ppm) thanks to its high surface/volume ratio, good repeatability and reversibility, fast response (40 s) and recovery times (18 s), and good selectivity for NO2 versus NH3, O-3 and CO. All these performances obtained at RT are encouraging for low-power devices.