Early stage degradation of InAlN/GaN HEMTs during electrical stress

Early stage degradation of InAlN/GaN HEMTs submitted to OFF and semi-ON state stress at a drain bias of 50 V was investigated. Degradation in different parts of the device upon OFF and semi-ON state stress inferred from the comprehensive electrical characterization indicates predominantly an hot-electron degradation mechanism, as no degradation in the gate leakage current was observed for both stress conditions. Based on `end' resistance measurements suggesting more pronounced degradation in the drain and source resistance after OFF and semi-ON state stressing, respectively, it is speculated that impact ionization can play a role in the degradation of InAlN/GaN HEMTs.