Effects of surface passivation on breakdown of AlGaN/GaN high-electron-mobility transistors

Abstract

The effect of Si3N4 surface passivation on breakdown of AlGaN/GaN high-electron-mobility transistors was studied in detail by investigating dependences of the off-state breakdown voltage on temperature and gate reverse current, and by measuring electroluminescence distribution. Impact ionization in the channel which was triggered by the gate reverse current was responsible for the off-state breakdown. Surface passivation by Si3N4 film was effective to improve the off-state breakdown voltage. This has been explained by a change in the potential distribution due to suppression of electron trapping at the surface states, based on results of electroluminescence measurements.