Tungsten-Based Cost-Effective Gas Sensors for H2S Detection

• Published in: Chemosensors Vol. 9; no. 11; p. 295
• Main Authors: Fasquelle, Didier, Verbrugghe, Nathalie, Députier, Stéphanie
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.11.2021
• Subjects: Annealing; Atomic force microscopy; Conduction; Conduction model; Diffraction patterns; Dynamic response; Electric power; Gas detectors; gas sensor; Gas sensors; Gases; Heaters; Hydrogen sulfide; Morphology; Phase transitions; Response time; RF sputtering; Room temperature; Silicon substrates; Thin films; Tungsten; Tungsten oxides; WO3 thin film; X-ray diffraction; United States > US
• ISSN: 2227-9040; 2227-9040
• DOI: 10.3390/chemosensors9110295

Tungsten trioxide thin films were deposited on silicon substrates by non-reactive RF sputtering from a WO3 target at room temperature. The WO3 films were post-annealed at two different temperatures, 400 °C and 500 °C. The morphological and microstructural properties of these films were analyzed by using atomic force microscopy and X-ray diffraction. X-ray diffraction patterns only show WO3 oxide phases. The AFM images show different morphologies with smaller grains for the film annealed at 400 °C. WO3 sensing films and W heating elements were embedded in commercial cases for the fabrication of cost-effective gas sensors. The sensitivity and dynamic response of the sensors were analyzed under various concentrations of H2S, from 20 to 100 ppm, at SIMTRONICS SAS (3M Company, Saint Paul, MN, USA). A good sensitivity G/G0 of about 6.6 under H2S 100 ppm was obtained with the best sensor. An interesting dynamic response was observed in particular with a short response time. Additionally, the evolution of the sensitivity was studied, and a conduction model was proposed for explaining the conduction mechanism under H2S exposition.