Hydrogen Gas Sensing Characterizations Based on Nanocrystalline SnO_2 Thin Films Grown on SiO_2/Si and Al_2O_3 Substrates

摘要

High-quality nanocrystalline (NC) SnO_2 thin films were grown on SiO_2/Si and Al_2O_3 substrates using sol-gel spin coating method. The structural properties, surface morphologies and gas sensing properties of the NC SnO_2 were investigated. XRD measurements showed a tetragonal rutile structure and the diffraction peaks for NC SnO_2 thin films grown on Al_2O_3 substrates outperformed those of NC SnO_2 films grown on SiO_2/Si substrates. The surface morphology of the annealed SnO_2 thin films at 500°C appeared as polycrystalline with uniform nanoparticle distribution. Hydrogen (H_2) gas sensing performance of the NC SnO_2 was examined for H_2 concentrations ranging from 150 ppm to 1000 ppm at different temperatures (room temperature, 75 and 125°C) for over 50 min. The room temperature sensitivities for H_2 gas sensors based on NC SnO_2 thin films grown on Al_2O_3 and SiO_2/Si substrates was 2570% and 600%, respectively upon exposure to 1000 ppm of H_2 gas. While the sensitivity values at 125°C increased to 9200% and 1950%, respectively.