Efficient methane detection by Co doping of ZnO thin films

Here, we report on the Co-doping of ZnO thin films and on its role on detection of methane. The complementary investigations have been conducted in order to understand, explain and confirm the influence of the Co on the surface morphology and on the gas sensitivity exhibit at relatively low gas concentrations. The X-ray diffraction patterns indicate that the studied films present a single-phase wurtzite structure of ZnO and the X-ray Photoelectron Spectroscopy investigation confirms the successful incorporation of Co2+ ions into the ZnO lattice. The plane-view Scanning Electron Microscopy images reveal the increase of surface to volume ratio with the increase of the dopant concentration. We investigated, the sensitivity of the sensor-devices tailored using the Co-doped and undoped ZnO thin films respectively. The maximum sensitivity, to 600 ppm methane, was obtained at an operating temperature of 170 degrees C. After repeated sensing measurements, the obtained results show long-term sensors stability. (C) 2014 Elsevier Ltd. All rights reserved.