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

Abstract

Abstract In this paper, pristine and 1–10\u202fmol% 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 H2 gas characteristics of the sensors were tested towards H2 gas in concentration of 50–2000\u202f\u202fppm\u202fat operation temperature from 175\u202f°C to 275\u202f°C. The result indicated that among all the samples, 1\u202fmol% Co-doped SnO2 thin film exhibited the most reasonable response characteristics at 225\u202f°C, having a response magnitude of 59.04 and response time of 7s toward 2000 pmm H2 gas. The enhanced H2 gas sensing characteristics is possibly attributed to the smaller gain size and the formation of p-n heterojunction.