Exploration of New Sensing Electrode Materials for FET-type NOx Sensors with Fast Response

A FET type NO2 sensor fitted with NaNO2-RU/WO3 as a new auxiliary (sensing) layer was fabricated and tested for its NO2 sensing properties. The developed device responded to dilute NO2 of ppb concentrations (20-300 ppb) at 130 and 170 degrees C. The sensor signal (V-GS; gate-source voltage) is linearly proportional to the logarithm of NO2 Concentration, exhibiting the Nernstian response. It was found that the response speed was improved at lower operating temperature by adding Ru to the NaNO2WO3 auxiliary layer. It was suggested that Ru nanoparticles deposited in the auxiliary layer with a porous morphology improved the rate of adsorption and electrochemical reaction of NO2 occurring at the interface between the Au gate electrode and auxiliary layer.