Characterization and gas sensor testing of single and mixed metal oxides based on NiO and TiO2 thin films

We present results on single and mixed metal oxides based on NiO and TiO
2
thin films which are able to detect 1000 ppm of hydrogen and to operate at 200°C. These films with thickness in the range of 50–100 nm were prepared by DC reactive magnetron sputtering on alumina and silicon substrates. The XRD measurements revealed polycrystalline character of annealed thin films at 600°C, whereas as-deposited samples were confirmed to be amorphous. Sensor structures based on NiO/TiO
2
/Si worked at very low operation temperature of 150°C though their responses to hydrogen appear lower relative sensitivity in comparison with those prepared from single oxides.