A Gan Hfet Sensor For Respiration Monitoring

We investigated zinc oxide (ZnO) nanostructure gated gallium nitride (GaN) heterostructure field effect transistor (HFET) devices and explored their potential application in chemical sensing and monitoring of human respiration. The ZnO nanostructures were grown on aluminum gallium nitride (AlGaN)/GaN heterostructures by a hydrothermal solution process. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses revealed the high density growth of the ZnO nanorods. In consequence, both the carrier mobility of AlGaN/GaN heterostructures and device current reduced due to the ZnO nanostructure growth as deduced from Hall and current-voltage (I-V) characteristics. The response time of the devices were 3 minutes when they were exposed to hydrogen at the bias of 2V and temperature 200 degrees C in a controlled gas chamber. However, when the devices were exposed to human breath under normal atmospheric conditions, the typical response time was 2 seconds. The obtained results imply the potential use of the studied devices in low voltage compact breath sensing and non-contact monitoring of the human respiration.