Structural and gas-sensing properties of V2O5–MoO3 thin films for H2 detection

Structural and gas-sensing properties of the modified MoO3 thin films using a V2O5-overlayer have been investigated. The thin films were deposited by magnetron rf sputtering. The crystallite size of the V2O5–MoO3 thin films is significantly smaller than the pure MoO3 thin films. The electrical resistivity of the films could be drastically reduced. It is found that the H2-sensing properties of the rf sputtered MoO3 thin films can be improved markedly by addition of a V2O5-overlayer. The sensitivity of the sensor is strongly influenced by the thickness of the sputtered V-overlayers. The optimum operating temperature when considering the response time, recovery time and the sensitivity was found at 150°C. Very low cross-sensitivity could be observed towards NO2, NH3, CO, CH4 and SO2 gases. The 50% response (τ50) and the recovery time are about 20 s and 1 min, respectively. These results suggest V2O5–MoO3 thin films to be an excellent material for a low temperature, highly sensitive and selective H2 sensor.