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.