A New Degradation Mechanism Induced by DX-Centers in AlGaAs/InGaAs PM-HEMT´s

We show that a remarkable threshold shift ¿Vp and an increase in the saturation current ¿Ids can be observed in AlGaAs/InGaAs PM-HEMT´s submitted to high temperature (100°C - 200 °C) storage or hot-electron stresses for relatively short times (about 20 hours). An increase in Ids up to 40% has been observed. The increase is not permanent and can be recovered by a room or low temperature storage with no bias. We attribute this increase to: (a) thermally-activated detrapping of electrons from the DX-centers; (b) recombination of electrons trapped by DX centers with holes generated by impact-ionization; the consequent reduction in the trapped negative charge induces a shift in the threshold voltage and the observed Ids increase. This room-temperature degradation mechanism of PM-HEMT´s is described here for the first time.