Regular Article

Enhanced sensing properties of ZnO-SnO₂ based composite type gas sensor

¹ Department of Electronics and Communication Engineering, Tezpur University, 784028 Assam, India
² Department of Physics, Jadavpur University, 700032 Kolkata, India
³ Department of Electronics and Telecommunication Engineering, Bengal Engineering and Science University, 711103 Kolkata, India
⁴ Centre of Excellence in Green Energy and Sensors Systems, Bengal Engineering and Science University, 711103 Kolkata, India

^a e-mail: biplob.tezu@gmail.com

Received: 17 March 2015
Revised: 14 November 2015
Accepted: 3 December 2015
Published online: 13 January 2016

Abstract

Pure zinc oxide (ZnO) nanorods and zinc-tin oxide (ZnO-SnO₂) composites based gas sensors were fabricated and tested for favorable gas sensing functionality. Systematic and comparative study on sensing properties like response magnitude, selectivity, response and recovery times, etc. of both the sensors were done for three test gases viz., hydrogen, methane and carbon mono-oxide. The obtained results clearly demonstrate enhanced sensing characteristics of the sensor made up of ZnO-SnO₂ composites over that of pure ZnO nanorods based one. Fabricated sensors gave highest response and selectivity towards hydrogen at a relatively low temperature of 150 °C. The improved sensing properties of the sensor based on ZnO-SnO₂ composites were attributed to the combined effect of the formation of depleted layer at the surface of individual ZnO/SnO₂ microstructure as well as the formation of hetero-junction between ZnO and SnO₂ grains. Sensing mechanism involved in the composite type ZnO-SnO₂ based sensor has also been discussed.