AlGaN/GaN based SAW-HEMT structures for chemical gas sensors

This work present a new approach to design and fabrication of AlGaN/GaN based SAW-HEMT structures to be applied for chemical gas sensors operating in harsh environment. A direct on-chip integrated compatibility in the process technology of surface acoustic wave (SAW) structure and high electron mobility transistor (HEMT) was demonstrated. It enabled to integrate two different principles of gas sensing based on both SAW and HEMT. The functionality of two types of SAW structures and HEMT device was investigated. The measured amplitude characteristics of SAW structures revealed excitation at the centre peak frequency about 1.35 GHz and 1.7 GHz, respectively with a both good quality factor and stop-band rejection ratio. The detection electronic based on SAW oscillator was subsequently designed and simulated. It proved the expected function and properties.