Fabrication of alpha-Fe2O3 porous array film and its crystallization effect on its H2S sensing properties

The alpha-Fe2O3 porous array film is synthesized based on an alternative and flexible route by transferring a solution-dipped selforganized colloidal template onto device substrate and subsequent annealing treatment. The sensing properties of the film to H2S and other interfering gases were studied in detail. It was observed that porous array film annealed at 400 degrees C showed optimized sensing performance with both higher response and better selectivity to H2S than those annealed at 300 degrees C, 500 degrees C and 600 degrees C. Detailed researches indicated the grain size of the alpha-Fe2O3 porous array film was closely related to annealing temperature, in which the sensing properties to H2S was deeply affected by the crystallization effect. A possible gas sensing mechanism was thus proposed. Generally, the higher crystallinity leads to better selectivity while large grain size will decrease response. This work gives an alternative way to realize H2S detection with high response and selectivity.