Gas sensitive GaN/AlGaN-heterostructures

High electron mobility transistors (HEMT) based on GaN/AlGaN-heterostructures have been fitted with catalytically active platinum (Pt) gate electrodes to induce gas sensitivity. Due to the wide bandgap of group III-nitride materials, such transistors can be operated at temperatures high enough for triggering a wide range of gas sensing reactions at the Pt gate. Depending on gate porosity, either selective hydrogen sensors or sensors with a broad-band sensitivity towards a range of reducing and oxidizing gas species can be made. Applying porous Pt electrodes and sensor operation temperatures of about 400 °C, hydrogen (H2), carbon monoxide (CO), acetylene (C2H2) and nitrous oxide (NO2) could be detected via sizable changes in the source drain current.