Micro Semiconductor CO Sensors Based on Indium-Doped Tin Dioxide Nanocrystalline Powders

摘要

The precursors of SnO₂ or In₂O₃/SnO₂ nanocrystlline powders have been prepared by the sol-precipitation method. The precursors were calcined at different temperatures to prepare SnO₂ or In₂O₃/SnO₂ nanocrystalline powders with different particle sizes. The nanocrystallites were examined by differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). And then thick film CO sensors were fabricated using prepared SnO₂ or In₂O₃/SnO₂ nanocrystlline powders loaded with PdO_x. The composition that gave the highest sensitivity for CO was in the weight% ratio of 5 wt.% In₂O₃/SnO₂:PdO_x as 99:1(wt %). The composite material was found sensitive against CO at the working temperature 200 °C. It was found that the sensors based on In₂O₃/SnO₂ nanocrystalline system exhibited very short response time to CO at ppm level. These characteristics make the sensor to be a promising candidate for detecting low concentrations of CO.