Preparation of tungsten-doped zinc oxide thin films by co-sputtering for micro-gas sensing devices

Synthesis of a good nanostructure is a vital part in regards to achieving proper gas sensing characteristics. In this study, Tungsten (W) doped ZnO nanostructure is synthesized on micro electro mechanical systems (MEMS) device by co-sputtering process. Appropriate doping concentration to the sensing material is crucial for sensing properties, therefore, 5 different doping concentrations ranging from 0% W to 4% W to the ZnO structure are developed. The structural properties of all the W doped ZnO samples were characterized by Scanning electron microscope (SEM), X-Ray diffraction (XRD) analysis and Energy-dispersive X-ray spectroscopy (EDS) analysis. Sensing properties were calculated with different concentrations of H ₂ gas ranging from 20 ppm to 100 ppm. All of the W doped ZnO sensors were tested for H ₂ gas at working temperatures varying from 100 °C to 300 °C to detect the optimal doping concentration and optimal working temperature. At 150 °C, 3% W doped ZnO revealed 67% gas sensing response for 100 ppm H ₂ gas. Selectivity test with 5 different gases displayed that W doped ZnO sensor has good selectivity over H ₂ gas at 150 °C.