Nickel was used as a surface modification material to enhance the gas-sensing properties of SnO2 films. The thickness of the Ni modification layer was controlled by the sputtering time. The surface morphology and surface chemical composition of the surface modification layers of different thicknesses were analyzed by Field Emission Scanning Electron Microscopy (FESEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The gas sensitivity to clean air with a low hydrogen concentration of 1000 ppm of the modified tin dioxide thin films was investigated at temperatures from 20 degrees C to 100 degrees C. The results show that the thickness of the modification layer plays an important role in the enhancement of the gas-sensing properties and surface electric properties of SnO2 films. A Ni modification layer with a thickness of 50 nm on the surface of a SnO2 film can improve the hydrogen gas sensitivity of a SnO2 film up to 112%, and reduce the response time to 80s.

Keywords: SnO2; thin film; surface modification; gas-sensing properties