Characterisation of Nanostructured SnO2 Thin Films for Gas Sensing Applications Using RF Magnetron Sputtering

Background: Tin oxide thin films are well-established gas sensing materials for detecting reducing gases including LPG and CO, which pose domestic safety hazards in Nigerian households. Systematic characterisation of sputtered SnO2 thin films for optimised sensing applications fills a critical local fabrication gap. Aim: This study characterised nanostructured SnO2 thin films deposited by RF magnetron sputtering for application as LPG and CO gas sensors. Methods: SnO2 films were deposited on alumina substrates at substrate temperatures of 200, 300, and 400 degrees Celsius. Structural characterisation was conducted by XRD and AFM. Optical properties were measured by UV-Vis spectroscopy. Gas sensing performance toward LPG and CO at concentrations from 100 to 5000 ppm was evaluated at operating temperatures from 200 to 400 degrees Celsius. Results: Films deposited at 300 degrees Celsius showed the highest crystallinity and optimum grain size of 18 nm. Maximum sensitivity to 1000 ppm LPG was S = 64 at 280 degrees Celsius operating temperature. Response and recovery times were 12 and 28 seconds respectively. CO sensitivity was highest at 320 degrees Celsius. Conclusion: RF magnetron sputtered SnO2 films at 300 degrees Celsius substrate temperature exhibit optimised microstructure and gas sensing performance. The findings provide a fabrication baseline for locally manufactured domestic gas alarms. Keywords: SnO2 thin film, gas sensor, RF magnetron sputtering, LPG detection, nanostructure.