Surface Reinforcement Technology for Suppressing Hot-Carrier-Induced Degradations in p-GaN Gate Power HEMTs

Highly energetic "hot" carriers generated during both ON and semi-oN states have been identified as a predominant root cause of reliability issues inp-GaN gate power HEMTs. In this work, with plasma oxidation and high-temperature annealing, a surface reinforcement layer (SRL) is formed at the surface of both the p-GaN gate and the AlGaN barrier in the access region. At oN-state, the reinforced p-GaN surface exhibits enhanced immunity against hot-electron bombardment at the gate metaUp-GaN junction, and thus effectively prolongs the time-dependent-gate-breakdown (TDGB) lifetime. During the transient state of hard switching (i.e., the semi-oN state), the SRL formed at the AlGaN surface exhibits improved robustness under the stress of hot electrons generated from the channel. As a significant benefit, the dynamic oN-resistance degradation after long-term operation could be substantially suppressed.