'Hole Redistribution' Model Explaining the Thermally Activated RONStress/Recovery Transients in Carbon-Doped AlGaN/GaN Power MIS-HEMTs

RON degradation due to stress in GaN-based power devices is a critical issue that limits, among other effects, long-Term stable operation. Here, by means of 2-D device simulations, we show that the RON increase and decrease during stress and recovery experiments in carbon-doped AlGaN/GaN power metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) can be explained with a model based on the emission, redistribution, and retrapping of holes within the carbon-doped buffer ('hole redistribution' in short). By comparing simulation results with front-and back-gating OFF-state stress experiments, we provide an explanation for the puzzling observation of both stress and recovery transients being thermally activated with the same activation energy of about 0.9 eV. This finds a straightforward justification in a model in which both RON degradation and recovery processes are limited by hole emission by dominant carbon-related acceptors that are energetically located at about 0.9 eV from the GaN valence band.