Impact of OFF-State Stress on Dynamic RON of On-Wafer 100 V p-GaN HEMTs, Studied by Emulating Monolithically Integrated Half-Bridge Operation

This paper presents the electrical characterization of the on-resistance (RON) of on-wafer 100 V p-GaN power High-Electron-Mobility Transistors (HEMTs). This study assesses device degradation in the context of a monolithically integrated half-bridge circuit, considering both Low-Side (LS) and High-Side (HS) configurations. Since on-wafer samples have been characterized, a custom experimental setup was developed to emulate stress conditions experienced by the devices in the half-bridge circuit. A periodic signal (T = 10 mu s, TON = 2 mu s) switching from the OFF to the ON state was applied for a cumulative duration of 1000 s. Different OFF-state stress conditions were applied by varying the gate-source OFF voltage (VGS,OFF) between 0 V and -10 V. The on-resistance exhibited a positive drift over time for devices in either the LS or the HS configuration, with the latter showing a more pronounced degradation. Measurements at higher temperatures (up to 90 degrees C) were carried out to characterize the dynamics of the physical mechanism behind the degradation effects. We identified hole emission from C-related acceptor traps in the buffer as the main mechanism for the observed degradation, which is present in both the HS and the LS configurations. The additional degradation observed in the HS case was attributed to the back-gating effect, stemming from the non-null body-to-source voltage. Furthermore, we found that a more negative VGS,OFF further increases RON degradation, likely related to the higher electric field near the gate contact, which enhances hole emission from C-related acceptor traps.