Carbon Dioxide Sensing Characteristics of AlGaN/GaN High Electron Mobility Transistor with ZnO Nanorods

A CO2 sensor bascd on an AlGaN/GaN high electron mobility transistor (HEMT) was developed using ZnO nanorods as the sensing material. The sensor showed a reliable response to a wide range of CO2 concentrations from 500 to 100000 ppm at 300 degrees C. The CO2 response of the device was tested from 25 to 400 degrees C, and the sensor started to exhibit responsivitv to 30000 ppm CO2 gas at 150 degrees C. The responsivity increased with the ambient temperature until the temperature reached 300 degrees C, and it decreased from 350 to 400 degrees C. The maximum responsivity of the sensor with ZnO nanorods was 4.31% for 10% CO2 exposure at 300 degrees C. In addition, the effect of humidity on the CO2 sensing characteristics was investigated. AlGaN/GaN-heterostructure-based CO2 sensors functionalized with ZnO nanorods have high potential for applications in the chemical, medical, energy, and food industries.