Room temperature hydrogen gas sensor based on nanocrystalline SnO₂ thin film using sol–gel spin coating technique

High-quality nanocrystalline (NC) SnO₂ thin film was grown on SiO₂/Si substrate by sol–gel spin coating technique at low temperature. X-ray diffraction and field emission scanning electron microscopy results observed the high quality of the produced NC SnO₂ thin film. A metal–semiconductor-metal (MSM) H₂ gas sensor was fabricated utilizing palladium (Pd) metal and NC SnO₂ thin film. Hydrogen (H₂) sensing capabilities of the NC SnO₂ thin film were examined at room temperature (RT), and the sensitivity was 600 % in the presence of 1000 ppm of H₂. The sensing measurements for H₂ gas at different temperatures (RT to 125 °C) were repeatable for over 50 min. The sensor showed a sensitivity of 1950 % at 125 °C upon exposure to 1000 ppm of H₂. A significant variation in the sensitivity of the NC SnO₂ thin film sensor was noticed at different concentrations of H₂ at different operating temperatures. These high sensitivities are attributed to the increase in adsorption/desorption of gas molecules, which were achieved by increasing the porosity of the NC SnO₂ thin film surface by adding glycerin to the sol solution. The high sensitivity of this H₂ gas sensor at RT indicated that it has the capability to be used as a portable RT gas sensor.