NH3 sensing characteristics of pure and Al modified WO3 thin films

Ammonia sensing properties of pure and Al modified WO₃ thin films prepared using RF sputtering have been investigated. Both the sensor films exhibited a maximum response at an operating temperature of 250°C. Modification with Al has been demonstrated to improve the response kinetics in particular the response time (6 min) in comparison to that of pure WO₃ (8 min) towards NH₃ (100 ppm). Interestingly, both the sensor films showed an increase in resistance i.e., a p-type behavior upon exposure to NH₃.