Study of the Short-Circuit Capability and Device Instability of p-GaN Gate HEMTs by Repetitive Short-Circuit Stress

In this article, the device degradation of Schottky-type p-GaN gate high electron mobility transistors was studied under repetitive short circuit (SC) with various stress parameters. Moreover, for the first time, the device characteristics recovery kinetics were recorded and analyzed to reveal the device degradation mechanism. During the repetitive SC stress, prominent threshold voltage (V-TH) shift and substantial drain current reduction were observed. For the stringent SC stress (e.g., 100 SC cycles with V-gs = 6 V and V-dc = 60 V), the device exhibits irreversible degradation (e.g., Delta V-TH and Delta I-D). However, in contrast, the device shows a complete recovery after lenient SC stress. The device degradation mechanisms under repetitive SC stress were revealed by carrying out delicate device characterization including high-temperature SC stress and gate current together with device simulation. The trap states filling in p-GaN gate region during stress and subsequent electron detrapping after stress is responsible for the recoverable device degradation under lenient SC stress. For the stringent SC stress, driven by the higher electric-field, hot-electron induced defects in the p-GaN gate region together with electron trapping at passivation/III-Nitride interface close to the drain side lead to the irreversible device degradation. Potential guidelines are proposed for mitigating the repetitive SC degradation.