Quasi 2D-ZnO thin film for CO sensing at room temperature

In this work, a low-power sensing device for detecting carbon monoxide at room temperature using a quasi two-dimensional (Q2D) ZnO thin film is presented. The ZnO layer (thickness of 50 nm) used in this sensing device is realized with the atomiclayer deposition (ALD) technique on an Al2O3/Si substrate. The operating principle of the sensor is based on measuring resistance change of the ZnO thin film upon exposure to CO. The ZnO-based sensor shows a large response to CO in concentrations ranging from 10 to 150 ppm in air with 40% relative humidity at room temperature. The sensor is also tested in air with varied relative humidity from 0 to 60%. Results show that the sensitivity of the sensor to CO at room temperature is reduced with increasing the relative humidity.