Preparation of High-Performance Room Temperature ZnO Nanostructures Gas Sensor

Abstract

Zinc oxide (ZnO) nanostructures were deposited on glass substrates by physical vapor deposition technique. To improve the crystallinity of ZnO, oxidation treatment was conducted at 400◦ for 1 h in an atmospheric environment. The films characteristics of the films were examined by X-ray diffraction, ultraviolet-visible spectroscopy, atomic force microscopy, and scanning electron microscopy. The X-ray diffraction results illustrated that the deposited films have a polycrystalline hexagonal structure. The ultraviolet-visible spectrum showed that the transmittance of the ZnO film has an energy gap of about 3.225 eV. The atomic force microscopy images indicated that the films have good homogeneity, and the scanning electron microscopy images reveal that they consist of spherical nanosized grains with a granular surface. The ZnO films revealed good sensing performance to acetone and ethanol gases at an operating temperature of 25◦C with suitable recovery and response times. The sensitivity measured by homemade gas sensor system was approximately 21.39, 29.63, 23.8% for acetone gas, and 15.96, 21.28, 20.97% for ethanol gas, at 125, 250, 500 ppm concentrations, respectively.