Enhanced H2S sensing characteristics of Au modified Fe2O3 thin films

• Surface modification was successfully achieved by sputtering Au.
• Au modified (2.33 at% Au) films exhibit enhanced and selective response towards H2S with an n-type conductivity.
• Sensing mechanism based on spillover effect and formation of nano-Schottky barriers has been proposed.

H2S sensing characteristics of pure and Au modified Fe2O3 thin films have been investigated. Fe2O3 thin films were realized in two steps; first pure Fe films were deposited using electron-beam evaporation method and subsequently subjected to oxidation at 800 °C in O2 environment. Surface modification with Au was achieved by employing RF sputtering. Both pure and Au modified Fe2O3 samples exhibited an n-type conductivity pattern. Modification with 2.33 at% of Au resulted in an enhanced response of 538% towards 10 ppm of H2S at 250 °C, with response and recovery times of 1.65 and 27 min, respectively. The enhanced response has been attributed mainly to the dual role of Au i.e., forming nano-Schottky barriers with the host Fe2O3 matrix and as a promoter for the spillover effect.