Effect of V2O5 coating on NO2 sensing properties of WO3 thin films

WO3-based thin film micro-gas sensors coated with V2O5 layers were fabricated and NO2 gas sensing characteristics were measured. The silicon-based substrate embedded with Pt interdigitating electrodes and heater was prepared by MEMS technology. Vanadium pentoxide (V2O5) was sputtered on the WO3 thin film at room temperature. All the films were annealed in air at 600 °C for 4 h. The effect of the thickness of V2O5 layers on NO2 response has been investigated. The coating with a 20 nm V2O5 layer made the WO3 thin film more sensitive to NO2. In addition, reversible response behavior could be achieved. SEM photographs revealed that the WO3 thin film with the 20 nm V2O5 coating layer showed porous structure.