| 摘要 |
PROBLEM TO BE SOLVED: To provide a nitrogen oxide gas sensor which has a low resistance value without decreasing gas sensitivity. SOLUTION: A Pt electrode 4 as a heater is formed to the backside of an Si wafer 2, and two Pt electrodes 3 are formed for measuring a resistance to a surface. A sensor layer 1 is set on the Si wafer, whereby a nitrogen oxide sensor is obtained. At this point, by having the sensor layer 1 constructed in two layers of an upper part of a WO3 12 as an NO2-sensitive layer and making a lower part of an n-type oxide semiconductor (SnO2) 11 smaller in resistivity than that of WO3, the resistance value is lowered, while the gas sensitivity is kept as is.
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