Dual-Gas Sensor Based on the Pt NPs/AlGaN/GaN High Electron Mobility Transistor for H and NH Gases Detection<sub/><sub/>

Multisensitive gas sensors have been drawingincreasing attention in recent years. In this work, dual-gas detection of hydrogen (H-2) and ammonia (NH3) isdemonstrated based on the Pt NPs/AlGaN/GaN high elec-tron mobility transistor (HEMT) device by solely tuning theoperating temperature. Scanning electron microscopy (SEM)and atomic force microscope (AFM) results show that the3 nm-thick Pt layer is a porous film with roughness of 1.2 nm.According to the I-d-V-g curves, the device has a pronounced pinch-off characteristic with an on-to-off ratio of five ordersof magnitude. Interestingly, this device is a H(2)gas sensorbelow 150(degrees)C and it changes to NH(3)gas sensor above 180 degrees C.Our sensor has a high response of 280.4% at 200 ppm NH(3)gas and an ultrafast response time of 4 s at 220(degrees)C. Experimentally, the device has a clear response of 1.9% at 100 ppb,indicating very low limit of detection (LOD). The capability ofdual-gas detection makes it attractive for multigas detectionand electronic nose.