Role of oxygen in the OFF-state degradation of AlGaN/GaN high electron mobility transistors

The physical degradation of AlGaN/GaN high electron mobility transistors during OFF-state stress experiments has been systematically studied. Oxide particles and stringers were found to form along the gate edge of stressed devices. When the gate electrode is removed, pits are seen to have formed underneath each particle. The observed room-temperature oxidation process is strongly dependent on the duration of the electrical stressing and the electric field. Moreover, the oxidation can be significantly reduced in vacuum (3 x 10(-5) Torr), with a corresponding 30% reduction of current collapse. Finally, a degradation process with electric-field-driven oxidation of the AlGaN surface has been proposed. (C) 2011 American Institute of Physics. [doi:10.1063/1.3665065]