Dynamic RON Free 1.2 kV Vertical GaN JFET

Abstract

Dynamic on-resistance (RON) or threshold voltage (VTH) instability caused by charge trapping is one of the most crucial reliability concerns of some GaN high-electron mobility transistors (HEMTs). It has been unclear if this issue can be resolved using an alternative GaN device architecture. This work answers this question by characterizing, for the first time, the dynamic RON and VTH stability of an industrial vertical GaN transistor-NexGen’s 1200V/70mΩ fin-channel JFET, fabricated on 100 mm bulk GaN substrates. A circuit setup is deployed for the in-situ measurement of the dynamic RON under steady-state switching. The longer-term stability of RON and VTH is tested under the prolonged stress of negative gate bias and high drain bias. The vertical GaN JFET shows nearly no RON or VTH shift in these tests, which could be attributed to the low defect density of the GaN-on-GaN homoepitaxial growth, the absence of electric field crowding near the surface, and the minimal charge trapping in the native junction gate. These results present a critical milestone for vertical GaN devices towards power electronics applications.

Description
Keywords
power electronics, gallium nitride, JFET, on-resistance, threshold voltage, stability, reliability
Citation
X. Yang, R. Zhang, B. Wang, Q. Song, A. Walker, S. Pidaparthi, C. Drowley, Y. Zhang, "Dynamic RON Free 1.2-kV Vertical GaN JFET," IEEE Transactions on Electron Devices, vol. 71, no. 1, pp. 720-726, Jan. 2024, doi: 10.1109/TED.2023.3338140.