Fabrication and characterization of Ga-doped ZnO nanowire gas sensor for the detection of CO

Abstract We demonstrate an efficient CO sensor using Ga-doped ZnO (GZO) nanowires (NWs). Various GZO NWs are synthesized with Au catalysts on sapphire substrates by hot-walled pulse laser deposition. The deposition temperature of ZnO NWs was in the range of 800–900 °C. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) characterizations indicate that the obtained NWs have the well-crystallized hexagonal structure with customized Ga-doping concentration of 0–5 wt.%. The NWs have the diameter of about 50 nm and the length of about 8 µm. After depositing the Ag electrodes on both sides of the NW cluster, the resistance change is checked with the exposure to CO gas in the self-designed gas chamber that can facilitate the detection of the resistance change and the control of gas flow as well as temperature . The detected resistance modulations are 1.0 kΩ and 83.2 kΩ in the cases of 3 wt.% GZO and pure ZnO NW clusters, respectively, indication that we successfully customize the sensitivity of the gas sensors by controlled doping.