Group III-nitride devices for field effect based gas detection

We report about recent results on the sensor properties of novel gas-sensing devices based on group III-nitride materials. (Pt)-Schottky diodes as well as gas sensitive AlGaN/GaN heterostructure field effect transistors are characterized with respect to their temperature dependent sensitivity towards hydrogen and other oxidizing or reducing gases. Further investigation of the transient behaviour of gas sensitive (Pt)-GaN Schottky contacts reveals that up to device temperatures of 150°C hydrogen is stored on electronically active sites of the sensor system. We found hydrogen accumulation at the Pt/GaN interface accompanied by an accumulation of oxygen by elastic recoil detection analysis. GaN-based gas sensitive devices are demonstrated to combine high performance with a simple planar device processing technology.