Observation and mechanism of kink effect in depletion-mode AlGaAs/GaAs and AlGaAs/GaInAs HEMTs

The appearance and the mechanism of a kink effect (a sudden rise in the drain current) in the output I/V characteristics of depletion-mode conventional AlGaAs/GaAs and pseudomorphic AlGaAs/GaInAs high-electron-mobility transistors is reported for the first time. The kink is postulated to arise from impact ionisation in the 2-DEG. The generated electrons drift towards the drain, while generated holes are prevented from entering the AlGaAs layer by the heterojunction barrier, and are injected into the GaAs buffer layer. These holes subsequently combine with electrons on the source side of the channel.