H2S sensing property of porous SnO2 sputtered films coated with various doping films

Pure SnO2 films and Ag-, Cu-, Pt-, and Pd-doped SnO2 films were investigated for H2S sensing properties. SnO2 films were deposited by DC magnetron sputtering at various substrate temperatures and discharge gas pressures. As the discharge gas pressure increased and the substrate temperature decreased, the film became porous. Doping with Cu or Ag film improved the sensitivity, and the highest sensitivity was obtained in the porous SnO2 film coated with an Ag film 16 nm thick. According to the X-ray diffraction (XRD) pattern, Ag deposited on SnO2 film transformed to Ag2S Upon exposure to H2S. When the Ag-doped film sensor was operated at a low temperature, the sensitivity was extremely high, but the recovery was insufficient. By increasing the operation temperature, the recovery was improved but the sensitivity decreased. (c) 2006 Elsevier Ltd. All rights reserved.