Optimizing the gas sensing characteristics of Co-doped SnO2 thin film based hydrogen sensor

In this paper, pristine and 1-10 mol% Co-doped SnO2 thin film were prepared via sol-gel spin-coating technology. The crystalline structure and micro morphology of the prepared thin films were analyzed through XRD, TEM and HRTEM, confirmed that the dopants enter into the tetragonal rutile-type SnO2 and suppress the grain growth. Sensors based on these thin films were fabricated and the H-2 gas characteristics of the sensors were tested towards H-2 gas in concentration of 50-2000 ppm at operation temperature from 175 degrees C to 275 degrees C. The result indicated that among all the samples, 1 mol% Co-doped SnO2 thin film exhibited the most reasonable response characteristics at 225 degrees C, having a response magnitude of 59.04 and response time of 7s toward 2000 pmm H-2 gas. The enhanced H-2 gas sensing characteristics is possibly attributed to the smaller gain size and the formation of p-n heterojunction. (C) 2019 Elsevier B.V. All rights reserved.