Gas-sensing characteristics of modified-MoO3 thin films using Ti-overlayers for NH3 gas sensors

Abstract Thin films of modified MoO 3 using Ti-overlayers have been deposited by magnetron sputtering. The gas-sensing characteristics of the sensor element, the influence of the Ti-overlayers and their preparation parameters on the gas-sensitive properties of the sensors have been studied. It was found that the Ti-overlayer is very effective for enhancing the sensitivity and selectivity to NH 3 gas. The sensitivity of the sensor is strongly influenced by the process parameters and the thickness of the sputtered Ti-overlayers. The sensor, using a Ti-overlayer thickness of 50 nm, features the highest gas sensitivity towards NH 3 , while its cross-sensitivity to other gas such as H 2 , SO 2 and CO is comparatively small. The operating temperature of the sensor is 200°C.