Effect of temperature on CO detection sensitivity of ZnO nanorod-gated AlGaN/GaN high electron mobility transistors

Abstract

The carbon monoxide (CO) detection sensitivities of ZnO nanorod-gated AlGaN/GaN high electron mobility transistors were measured over a range of temperatures from 25–150 °C. Once the sensor was exposed to the CO-containing ambient, the drain current, I, of the high electron mobility transistors increased due to chemisorbed oxygen on the ZnO surface reacting with CO, forming CO2 and releasing electrons to the oxide surface. Although the sensor could detect CO as low as 100 ppm at room temperature, the detection sensitivity, ΔI/I, was only around 0.23%. By increasing the sensor temperature to 150 °C, the detection sensitivity was improved by a factor of over 30% to 7.5%.