Necked ZnO nanoparticle-based NO2 sensors with high and fast response

Abstract

The NO2 gas sensing characteristics of semiconductor type gas sensors with channels composed of necked ZnO nanoparticles (NPs) were investigated in this study. The heat treatment of the NPs at 400 degrees C led to their necking and coarsening. The response of the necked-NP-based sensors was as high as 106 when exposed to 0.2 ppm of NO2 at 200 degrees C. As the concentration of NO2 increased to 5 ppm, their response was enhanced to approximately 400. During the repeated injection of NO2 gas with a concentration of 0.4 ppm, the sensors exhibited stable response characteristics. Furthermore, the 90% response and recovery times of the gas sensor were as fast as 13 and 10s, respectively. These observations indicate that the non-agglomerated necking of the NPs induced by the heat treatment significantly enhances the gas sensing characteristics of the NP-based gas sensors. (C) 2009 Elsevier B.V. All rights reserved.