Performance of Si-Doped WO3 Thin Films for Acetone Sensing Prepared by Glancing Angle DC Magnetron Sputtering

This paper presents the acetone sensing characteristics of Si-doped (1 at.%) tungsten oxide thin films prepared by glancing angle dc magnetron sputtering. The performance of Si-doped WO3 sensors in the concentration range of 0.04-3.8 ppm at operating temperatures of 150 degrees C-425 degrees C has been investigated. Doping of the tungsten oxide film with Si significantly decreases the limit of detection of acetone compared with the pure WO3 sensors reported in the literature. The gas sensor's response (S) to acetone was defined as the resistance ratio S = R-air/R-gas, where R-air and R-gas are the electrical resistances for the sensor in air and in gas, respectively. The maximum response measured in this experiment was S = 40.5. Such response was measured in the presence of 3.8 ppm of acetone at an operating temperature of 425 degrees C using a Si-doped (1 at.%) WO3 thin film deposited at 300 degrees C and annealed at 300 degrees C for 4 h in air. The films phase composition, microstructure, and surface topography have been assessed by X-ray diffraction, scanning electron microscope, atomic force microscope, and energy dispersive X-ray spectroscopy methods.