High voltage AlGaN/GaN High-Electron-Mobility Transistors (HEMTs) employing oxygen annealing

The blocking characteristics of AlGaN/GaN High-Electron-Mobility Transistors (HEMTs) were considerably improved by an oxygen (O
₂
) annealing. This proposed annealing, which was performed before Schottky contact formation, successfully decreased the leakage current though the buffer region by about six orders of magnitude and had no effect on the current capability of the active region. The suppressed leakage current may be due to the improved surface condition induced by the reaction between oxygen and the AlGaN/GaN heterostructure. The proposed device employing the O
₂
annealing exhibited a suppressed leakage current and a high breakdown voltage of 1140 V without any surface passivation or edge termination structure.