Work function effects of ZnO thin film for acetone gas detection

ZnO thin films were deposited on alumina substrates under various conditions and then plasma treated with the goal of fabricating ZnO sensors for acetone gas detection. The ZnO thin films were deposited using the radio frequency (RF) magnetron sputtering method with a RuO2 micro heater and Ru electrode. In order to control the work function of the sensor, ZnO thin films were deposited under the various deposition conditions (RF power, distance from target to substrate) and then plasma treated. The sensitivity of the ZnO sensors was measured in the air or in acetone gas (500 and 1500 ppm) at a substrate temperature of 250 °C, which was heated using a RuO2 micro-heater. The sensitivity of the ZnO sensors was dependent on the work function of the ZnO thin films. Moreover, the work function of the ZnO thin films was also dependent on the binding energy of oxygen atoms. The results of this study indicate that the work function of the as-deposited or plasma treated ZnO thin films were sufficient for these films to be used as a ZnO sensor for acetone gas detection.