CO Sensor Using ZnO Thin Film Derived by RF Magnetron Sputtering Technique

In this paper, the fabrication and results of zinc oxide (ZnO) thin-film CO gas sensor are discussed. The thin film of c-axis oriented ZnO is deposited on Si/SiO₂ substrate at room temperature using RF magnetron sputtering technique. The deposited ZnO film is annealed at different temperatures starting from 200 °C to 400 °C. The crystalline structural properties are analyzed by X-ray diffraction technique and the preferred orientation of ZnO thin film (along 002 direction) is found at 400 °C. Further, ZnO thin film is characterized by scanning electron microscopy and surface profilometer to analyze the surface properties and thickness. The deposited ZnO film is supported by Au electrodes and Pt microheater to couple the sensing signal with outer circuitry. A measurement system is also developed to measure the gas sensing properties and the results are discussed in detail.