Electrical properties of tungsten trioxide films

Selectively doped semiconducting metal oxide (SMO) films have been shown to have applications as the sensing element in gas microsensors. Critical to the design and operation of these sensors is the SMO film. In the present work, the electrical properties of both intrinsic and extrinsic (doped with gold) tungsten trioxide (WO₃) films, which selectively sorb hydrogen sulfide (H₂S), are investigated. Hall effect measurements are performed as a function of film thickness, temperature, gold‐doping concentration, and H₂S gas concentration. The conductivity was found to be n type and strongly dependent on temperature, gold doping concentration, and H₂S gas concentration and less dependent on film thickness. The mobility was relatively high while the intrinsic carrier concentration was low when compared to typical semiconductor materials. The conductivity was shown to exhibit anomalous behavior at certain temperatures and H₂S gas concentrations.