Hot electrons and time-to-breakdown induced degradation in AlGaN/GaN HEMTs

This paper reports on the experimental evidences of hot electrons induced degradations of AlGaN/GaN HEMTs submitted to on-state stress tests. Thanks to the use of a combined electrical and electroluminescence characterization we demonstrate that: (a) exposure of devices to on-state stress can induce a remarkable decrease in drain current; (b) drain current degradation is due to electron trapping induced by hot electrons in the gate-drain access region; (c) degradation rate strongly depends on the intensity of the EL signal emitted by the devices during stress, while it has a negligible dependence on temperature. Finally, we derived an accelerated degradation law for GaN HEMT submitted to accelerated bias test, by using the intensity of the EL signal as a measure of the stress acceleration factor.