Fabrication and gas sensing characteristics of pure and Pt-doped γ-Fe2O3 thin film

The γ-Fe2O3 thin films were prepared by the reduction and the oxidation of Fe–O thin films processed by plasma-enhanced chemical vapor deposition (PECVD) technique. The phase transformation of Fe–O thin films was mainly controlled by the substrate temperature and rf power. The Fe–O amorphous phase was initially obtained at the deposition rf power over 150 W. The Fe–O amorphous phase could be transformed into γ-Fe2O3 phase under the controlled reduction and oxidation at 280–320°C. Based on the result of sensing characteristics, the prepared γ-Fe2O3 thin film showed the excellent sensitivity to i-C4H10 and H2 gas. The sensitivities of γ-Fe2O3 thin film to i-C4H10 and H2 gas were 60 and 90% in 500 ppm environments and 76 and 96% in 3000 ppm environments, respectively. On the other hand, the Pt-addition to γ-Fe2O3 thin film does not improve the gas sensitivity in H2 atmosphere.