Electron Beam Evaporation of Tungsten Oxide Films for Gas Sensors

摘要

Pure and iron incorporated nanostructured Tungsten Oxide (${hbox{WO}}_{3}$ ) thin films were investigated for gas sensing applications using noise spectroscopy. The ${hbox{WO}}_{3}$ sensor was able to detect lower concentrations (1–10 ppm) of ${hbox{NH}}_{3}$ , CO, ${hbox{CH}}_{4}$ , and Acetaldehyde gases at operating temperatures between 100 $^{circ}{hbox{C}}$ to 250 $^{circ}{hbox{C}}$ . The iron-doped Tungsten Oxide sensor ( ${hbox{WO}}_{3}$:Fe) showed some response to Acetaldehyde gas at relatively higher operating temperature (250 $^{circ}{hbox{C}}$) and gas concentration of 10 ppm. The sensitivity of the ${hbox{WO}}_{3}$ sensor towards ${hbox{NH}}_{3}$, ${hbox{CH}}_{4}$ and Acetaldehyde at lower operating temperatures (50 $^{circ}{hbox{C}} $–100 $^{circ}{hbox{C}}$) was significant when the sensor was photo-activated using blue light-emitting diode (Blue-LED). From the results, photo-activated ${hbox{WO}}_{3}$ thin film that operates at room temperature appeared to be a promising gas sensor. The overall results indic-n-nated that the ${hbox{WO}}_{3}$ sensor exhibited reproducibility for the detection of various gasses and the ${hbox{WO}}_{3}$ :Fe indicated some response towards Acetaldehyde gas.