Physical properties investigation and gas sensing mechanism of Al: Fe2O3 thin films deposited by spray pyrolysis

Abstract We present the successful synthesis and characterization of pure and Al: Fe2O3 thin films prepared by spray pyrolysis. The XRD analysis showed a rhomboedric structure with (104) as a preferential orientation for all the layers. AFM and SEM observations exhibited a dense surface with grains uniformly distributed. Optical measurements demonstrated that Al: Fe2O3 (y = 6 and 8 at. %) were highly transparent. In addition, the band gaps values found in the range from 1.98 to 2.17 eV. Hall Effect measurements indicated an n-type conductivity with the lowest resistivity of 2.68 x 102 Ω.cm which reached for the 8 at. % Al: Fe2O3 thin films. Moreover, Al: Fe2O3 thin film based sensor demonstrated a good response to a small amount of ethanol vapor with the adequate response and recovery period at a low operating temperature equal to 250 °C.