Abstract
We investigated the sensing characteristics of NO2 gas sensors based on Pd-AlGaN/GaN high electron mobility transistors (HEMTs) at high temperatures. In this paper, we demonstrated the optimization of the sensing performance by the gate bias, which exhibited the advantage of the FET-type sensors compared to the diode-type ones. When the sensor was biased near the threshold voltage, the electron density in the channel showed a relatively larger change with a response to the gas exposure and demonstrated a significant improvement in the sensitivity. At 300 °C under 100 ppm concentration, the sensor’s sensitivities were 26.7% and 91.6%, while the response times were 32 and 9 s at VG = 0 V and VG = −1 V, respectively. The sensor demonstrated the stable repeatability regardless of the gate voltage at a high temperature.
Highlights
Owing to the unique properties of the nanomaterials such as great adsorptive capacity due to the large surface-to-volume ratio, the ability of tuning electrical properties by controlling the composition and the size of the nanomaterial, the easy configuration and integration in low-power microelectronic systems, the gas sensors based on nanotechnology are excellent candidates for sensitive detection of chemical and biological species [1,2,3,4]
The development of ppm-level NO2 gas sensors that can operate at very high temperatures is necessary
AlGaN/GaN high electron mobility transistors (HEMTs)-type sensors were fabricated at the Inter-University Semiconductor Research Center (ISRC), Seoul, Korea
Summary
Owing to the unique properties of the nanomaterials such as great adsorptive capacity due to the large surface-to-volume ratio, the ability of tuning electrical properties by controlling the composition and the size of the nanomaterial, the easy configuration and integration in low-power microelectronic systems, the gas sensors based on nanotechnology are excellent candidates for sensitive detection of chemical and biological species [1,2,3,4]. The LC50 (the lethal concentration for 50% of those exposed) for a 1-h exposure of NO2 for humans has been estimated to be 174 ppm [5]. Nitrogen dioxide gas is emitted from the burning of fuel, the exhaust of furnaces and power plants, etc. The development of ppm-level NO2 gas sensors that can operate at very high temperatures is necessary
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