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, LGD. While breakdown voltages and critical voltages scale almost linearly with LGD, 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.