Highly Selective and Response NO2 Gas Sensor Based on Au-Coated ZnO Thin Films

Abstract

This paper investigated the nitrogen dioxide and ammonia gas-sensing properties of Au-coated ZnO thin films obtained by a hybrid method combining atomic layer deposition (ALD) and thermal evaporation techniques. The scanning electron microscopy (SEM) results showed Au nanoparticles, and the thickness of the Au-coated ZnO thin films was approximately 33 nm. X-ray photoelectron spectroscopy (XPS) results confirmed that Au nanoparticles were coated on the surface of the ZnO thin films. The gas sensor based on Au-coated ZnO thin films was tested upon exposure to nitrogen dioxide and ammonia gases with concentrations of 10 ppm to 90 ppm at 250 oC. Furthermore, the Au-coated ZnO thin films showed an excellent response at a low nitrogen dioxide concentration (10 ppm) with a relative response value of 574%. Moreover, the gas sensor exhibited a high relative and selectivity response to nitrogen dioxide gas.