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 NO2 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 to 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 vs. NH3, O3 and CO. All these performances obtained at RT are encouraging for low-power devices.