Effect of temperature on CO sensing response in air ambient by using ZnO nanorod-gated AlGaN/GaN high electron mobility transistors

AlGaN/GaN high electron mobility transistors (HEMTs) functionalized with ZnO nanorods were used for sensing CO in the concentration range of 50–500ppm balanced with air at ambient and temperatures from 25 to 250°C. An increase of the HEMT drain current was observed for exposure to the CO-containing ambient. The sensing limitation was improved from 100ppm to 50ppm by increasing the sensor temperature from room temperature to 250°C. The sensing response was also enhanced from 0.09% to 0.34% by increasing the sensor temperature. Reliable and repeatable current changes with the introduction of a low CO concentration of 50ppm and also rapid response times of ∼40s and recovery times ∼15s were demonstrated.