Dynamic $R_{{on}}$ dispersion due to buffer traps is a well-known issue of GaN power high electron mobility transistors (HEMTs), critically impacting their performance and stability. Several works show that the dynamic $R_{{on}}$ reaches a maximum for some off-state drain-source voltage ( $V_{DS,{off}}$ ) value typically in the range of several hundred volts and then partially recovers to smaller values. In this work, we propose a quantitative explanation for this behavior, attributing it to the charging/discharging dynamics of carbon (C)-related buffer traps. We characterize the dynamic $R_{{on}}$ in packaged p-GaN gate AlGaN/GaN HEMTs with a custom measurement setup. We find that in these devices, the relative $R_{{on}}$ increase reaches a maximum of 60% for $V_{DS,{off}} ≈ 100$ -200 V, partially recovering to about 30% as $V_{DS,{off}}$ is raised to 500 V. We ascribe this behavior to the partial neutralization of C-related acceptor traps in the buffer due to trapping of holes produced by a high-field generation mechanism. This explanation is supported by calibrated 2-D numerical simulations, that successfully reproduce the experimentally observed $R_{{on}}$ reduction only when including a hole generation mechanism.

In this article, we separately investigate the role of electric field and device self-heating (SHE) in enhancing the charge emission process from Fe-related buffer traps (0.52 eV from E _c ) in AlGaN/GaN high electron mobility transistors (HEMTs). The experimental analysis was performed by means of drain current transient (DCT) measurements for either: 1) different dissipated power ( P _D,steady ) at constant drain-to-source bias ( V _DS,steady ) or 2) constant P _D,steady at different V _DS,steady 's. We found that: 1) an increase in P _D,steady yields an acceleration in the thermally activated emission process, consistently with the temperature rise induced by SHE and 2) on the other hand, the field-effect turned out to be negligible within the investigated voltage range, indicating the absence of the Poole-Frenkel effect (PFE). A qualitative analysis based on the electric field values obtained by numerical simulations is then presented to support the interpretation and conclusions.

In this brief, we investigate the bidirectional threshold voltage drift (VT) following negative-bias temperature instability (NBTI) stress in carbon-doped fully recessed AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs). Several stress conditions were applied at different: 1) gate biases (VGS,STR); 2) stress times (tSTR); and 3) temperatures (T). Both negative and positive VT (thermally activated with different activation energies, EA) were observed depending on the magnitude of VGS,STR. In accordance with the literature, observed VT < 0 V (EA ≈ 0.5 eV) under moderate stress is attributed to the emission of electrons from oxide and interface traps. Instead, VT > 0 V (EA ≈ 0.9 eV) under high stress is attributed to the increased negatively ionized acceptor trap density in the buffer associated with carbon doping.

In this paper, we investigate the influence of Poole–Frenkel effect (PFE) on the dynamic R _ON transients in C-doped p-GaN HEMTs. To this aim, we perform a characterization of the dynamic R _ON transients acquired during OFF-state stress (i.e. V _GS,STR = 0 V < V _T, V _DS,STR = 25–125 V) and we interpret the results with the aid of numerical simulations. We find that dynamic R _ON transients at room temperature accelerate with V _DS,STR ^1/2, which is signature of PFE, as further confirmed by the simultaneous decrease of the activation energy (E _A) extracted from the Arrhenius plot of the dynamic R _ON transients at V _DS,STR = 50 V and T = 30 °C–110 °C. Results obtained by means of calibrated numerical simulations reproduce the exponential dependence of transients time constants (τ) on V _DS,STR ^1/2 and consequent E _A reduction only when including the PFE-enhancement model of hole emission from dominant acceptor traps in the buffer related to C doping. This result is consistent with the ‘hole-redistribution’ model that considers hole emission from acceptor traps (rather than electron capture) as the mechanism underlying dynamic R _ON increase during OFF-state stress.

In this paper, we investigate the evolution of threshold voltage (V_TH) and on-resistance (R_ON) drifts in the silicon carbide (SiC) power metal-oxide-semiconductor field-effect transistors (MOSFETs) during the switch-mode operation. A novel measurement setup for performing the required on-the-fly characterization is presented and the experimental results, obtained on commercially available TO-247 packaged SiC devices, are reported. Measurements were performed for 1000 s, during which negative V_TH shifts (i.e., V_TH decrease) and negative R_ON drifts (i.e., R_ON decrease) were observed. To better understand the origin of these parameter drifts and their possible correlation, measurements were performed for different (i) gate-driving voltage (V_GH) and (ii) off-state drain voltage (V_PH). We found that V_TH reduction leads to a current increase, thus yielding R_ON to decrease. This correlation was explained by the R_ON dependence on the overdrive voltage (V_GS–V_TH). We also found that gate-related effects dominate the parameter drifts at low V_PH with no observable recovery, due to the repeated switching of the gate signal required for the parameter monitoring. Conversely, the drain-induced instabilities caused by high V_PH are completely recoverable within 1000 s from the V_PH removal. These results show that the measurement setup is able to discern the gate/drain contributions, clarifying the origin of the observed V_TH and R_ON drifts.

In this letter, we investigate the on-resistance (RON) instability in p-GaN power HEMTs induced by a positive or negative gate bias ( ${V}_{\text {GB}}$ ), following the application of a quasi-static initialization voltage ( ${V}_{\text {GP}}$ ) of opposite sign. The transient behavior of this instability was characterized at different temperatures in the 90–135 °C range. By monitoring the resulting drain current transients, the activation energy as well as time constants of the processes are characterized. Not trivially, both RON increase/decrease were found to be thermally activated and with same activation energy. We attribute the thermal activation of both (RON) increase/decrease to the charging/discharging of hole traps present in the AlGaN barrier in the region below the gate.