Nanostructured tin dioxide and tungsten trioxide chemiresistive gas sensors were fabricated using a glancing angle deposition technique. The sensing films were grown using pulsed direct current magnetron sputtering at room temperature with continuous substrate rotation onto sensor platforms compromised of platinum electrodes, a thin film heater, and a resistance temperature device integrated onto a sapphire wafer. Structural and morphological properties of the films were characterized by X-ray diffraction and high resolution scanning electron microscopy. Both as-deposited and post-deposition air annealed tin dioxide and tungsten trioxide exhibit nanorod morphology with extremely high surface to volume ratios. These nanostructured sensors were exposed to 25 ppm ethylene gas and their response was compared to gas sensors fabricated using conventional normal incidence film deposition. The nanorod morphology induces a substantial increase in sensitivity. A thin gold catalyst layer deposited onto the sensors was found to markedly increase the surface reactivity towards ethylene and yield high sensitivity, especially for tungsten trioxide sensors.
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