Effect of Acceptor-Type Traps in GaN Buffer Layer on Current Collapse of ε-Ga₂O₃/GaN HEMTs

Abstract

In this paper, we investigate the effects of acceptor-type traps in the GaN buffer layer on current collapse in ε-Ga2O3/GaN high-electron-mobility transistors (HEMTs). Numerical simulations were conducted across a wide range of trap densities (1 × 1015 cm−3 to 1 × 1018 cm−3) and energy levels (0.4 eV to 1.0 eV). The results show that as trap density increased, current dispersion increased to a peak value of 0.34 A/mm, with a dispersion percentage of 30.91%. Higher trap energy levels (0.6 eV, 0.8 eV, and 1.0 eV) reduced current collapse due to limited electron trapping. Conversely, at a lower energy level of 0.4 eV, rapid recovery prevented significant net current loss despite initial current collapse. For comparison, Al0.28Ga0.72N/GaN HEMTs were also analyzed, showing a similar trend in the effect of trap energy levels, but with a non-monotonic dependence on trap density due to the lower two-dimensional electron gas (2DEG) concentration. These findings highlight the importance of optimizing trap density and energy levels to mitigate current collapse and improve device performance. Such optimizations can make ε-Ga2O3/GaN HEMTs more reliable and efficient for high-power applications requiring stability and robustness. © The Minerals, Metals & Materials Society 2025