Normally-Off β-Ga2O3 Trench-Gate Current-Aperture Vertical Electron Transistors With High-Voltage Drain--Stress Stability

Abstract

Enhancement-mode (E-mode) $\beta $ -Ga₂O₃ transistors are highly desired for kV-class power switching, but their realization remains challenging due to the lack of effective p-type doping. Fin- and trench-gate structures have been employed to achieve the E-mode operation, but they suffer gate-corner electric-field (E-field) crowding and thereby reliability concerns. Here we propose the deployment of the current aperture vertical electron transistor (CAVET) architecture to shield the trench-gate from high E-field. The fabricated trench-gate CAVET achieves a threshold voltage of 2.1 V, a small transfer hysteresis of 50 mV, a specific on-resistance of 13.4 m $\Omega \cdot $ cm², and a breakdown voltage of 1140 V. Its stability is investigated under high-bias drain stress, presenting small parametric shifts after 600 V stress for 1000 s. When elevating the stress bias to 1000 V, the device presents no gate failure, validating the effective E-field shielding. Notably, such high-bias stability tests have not been previously reported for Ga₂O₃ vertical transistors. Therefore, this work demonstrates a promising architecture for normally-off, kV-class $\beta $ -Ga₂O₃ power transistors with high-voltage drain-stress stability.