A new preparation method for sputtered MoO3 multilayers for the application in gas sensors

A new method for the preparation of sputtered MoO3 multilayer thin films for the application in gas sensors has been developed. A remarkable change of the crystallinity and the microstructure compared to the whisker-like structure of conventionally sputtered MoO3 single-layer films is found. The multilayer films have a dense and a smooth structure with a small crystallite size. This preparation method evidences that the H2 sensing properties, such as sensitivity, selectivity, response time and long-term stability of the sensors can be improved. The cross-sensitivity towards NO2, NH3, CO, CH4, and SO2 is low. The response time (τ50) to H2 can be drastically reduced from 40 s for the single-layer film to 10 s. The sensor exposes a very high response to H2 with a good signal linearity for high concentrations ranging from 2000 to 9000 ppm.