Annealing Time Effects on the ethanol sensing properties of nano-crystalline SnO٢ thin films prepared vacuum Evaporation

In this work, annealing time effects on the gas sensing properties of nano-crystalline SnO٢ thin films have been investigated. . Pure SnO٢ thin films, with the thickness of ٣٠٠ nm, have been grown using vacuum evaporation method on glass substrate. In order to be used as gas sensors, the samples were annealed at ٤٠٠ ºC. Optimal annealing time was assessed by using different time periods (١, ٢, ٣ and ٤h) for thin films annealing process. After these treatments, the electrical properties of sensors to ethanol have been studied. The results showed that the films annealed at ٢ hours have the highest sensitivity, lower response time. In addition, it was shown that longer annealing time will result in the decrease of sensitivity, response rate and the increase of response time. The surface morphology of SnO٢ films was characterized by a Scanning Electron Microscope (SEM). The grain size are ١٠, ١٦, ٢٣ and ٣٠ nm, respectively.

Keywords:

Gas sensors , Tin Oxide , Annealing time , Thin films