Nanocrystalline indium oxide-doped tin oxide thin film as low temperature hydrogen sensor

Hydrogen gas, within the concentration range of 100 ppm-4 vol.%, is successfully sensed at lower operating temperatures, 25 and 50degreesC, using the Pt-sputtered sol-gel dip-coated nanocrystalline (6-7 nm) 6.5 mol% In2O3-doped SnO2 semiconductor thin (100-150 nm) film sensor. Typically, for 1000 ppm of hydrogen, the maximum sensitivity values of 32 and 1600% are observed at 25 and 50degreesC, respectively; while for 2 vol.% hydrogen, the maximum sensitivity values of 50 and 70,000% are recorded at 25 and 50degreesC, respectively. At 25degreesC, for 4 vol.% (explosive limit as set by NASA) hydrogen, the maximum hydrogen gas sensitivity values of 107,887 and 2083% are observed for the Pt-sputtered thin films calcined at 500 and 600degreesC, respectively. (C) 2003 Elsevier B.V. All rights reserved.