A comparative study of gas sensing properties of SnO₂ and SnO₂:Mo films grown by magnetron sputtering

Pure and Mo-doped SnO₂ films were deposited on the glass substrates by sputtering from the metallic Sn and Mo targets with subsequent annealing in air at various temperatures from 500 to 700°C. The properties of the grown films were studied for gas sensor applications. The optimum annealing temperature was 500°C. The pure and the doped films annealed at this temperature showed best sensitivities for both alcohol and amine gases. While there was no distinct difference between the pure and the Mo-doped films for the alcohol gases at the operating temperature of 400°C, the latter showed clearly improved sensitivities at lower temperature (300°C), e.g., the ethanol sensitivity of SnO₂:Mo was 16.47 and 7.97 at 400 and 300°C, respectively, compared to 14.77 and 2.92 for the pure SnO ₂. However, the SnO₂:Mo films responded much more sensitively to the amine gases than pure SnO₂ films. With the optimum Mo content of 7.3 atom %, the doped films showed a sensitivity of as high as 29.49 for hydrazine.