  The degradation mechanisms of AlGaN/GaN HEMTs adopting Fe and C co-doping,
with high and low carbon doping concentration were investigated by means of
hot-electron step stress and 24 hours stress tests. Firstly, DC and EL
characterization at room temperature are summarized, then the parametric
evolution during hot-electron step stress tests at the semi-on state was
compared, the assumption for the degradation mechanism is that hot-electrons
activated the pre-existing traps in the buffer, attenuate the electric field in
the gate drain access region and damaging the gate contact, the parametric
evolution during constant stresses is discussed.
