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.