Short Term Reliability and Robustness of ultra-thin barrier, 110 nrn-gate AlN/GaN HEMTs

Short-term reliability and robustness of 110 nm AlN/GaN HEMTs has been evaluated by means off-state, semi-on state and on-state step stress tests on devices having different gate-drain distance, L
_GD
. While breakdown voltages and critical voltages scale almost linearly with L
_GD
, failure mode remains almost unchanged in the nine device groups, and consists in an increase of gate leakage, accompanied by a positive shift of threshold voltage. In off-state, electroluminescence images detect the presence of localized leakage paths which may correspond to dislocations and act as preferential paths for electron trapping. Degradation is therefore preliminary attributed to hot-electron trapping, enhanced by electric fields.