Abstract

Tin oxide (SnO2)-based thin films were deposited on alumina printed circuit boards via electron beam evaporation to fabricate CO2 gas sensors operating at room temperature. Femtosecond laser surface nanotexturing was applied as a novel approach to optimize key gas sensitivity parameters, including surface roughness and grain size. Raman and X-ray photoelectron spectroscopy revealed that the sensitive layer consists of a 1 μm SnO film with a non-stoichiometric SnO2 upper layer for the as-deposited film. The electronic disparity between these layers forms a native SnO-SnO2 interface, creating a p-n junction that enhances sensor sensitivity. This sensor shows a sensing response ranging from 7% to 20% for CO2 concentrations of 1000 to 2000 ppm, and up to 40% at 5000 ppm. Laser irradiation introduced periodic surface structures (~ 800 nm), increasing the roughness and the number of active sites for the gas sensing. Although no significant improvements were observed in terms of sensitivity, the fs-laser treated sensor exhibited enhanced stability and reproducibility, indicating its potential for low-energy consumption gas sensing platforms for indoor air quality applications.

Autori

Eleonora Bolli, Alessandro Bellucci, Matteo Mastellone, Alessio Mezzi, Stefano Orlando, Riccardo Polini, Raffaella Salerno, Antonio Santagata, Veronica Valentini, Daniele Maria Trucchi

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