Group-III-nitride based gas sensing devices

The paper reports on novel gas sensing devices based on LII-nitride materia ls. Both platinum GaN Schottky diodes as well as high-electron-mobility tra nsistors formed from GaN/AlGaN heterostructures with catalytically active p latinum gates were investigated. The performance of these devices towards a number of relevant exhaust gas components (H-2, HC, CO, NO) was tested. Th e test gas concentrations as well as the composition of background gases we re chosen to simulate exhaust gas emissions from lean-burn engines. We foun d that GaN-based devices with platinum electrodes are mainly sensitive to h ydrogen and unsaturated hydrocarbons with a sizeable cross-sensitivity to C O. furthermore a strikingly dissimilar gas sensing behavior has been observ ed with respect to saturated hydrocarbons on the one hand and to hydrogen a nd unsaturated hydrocarbons on the other hand.