Evidence of Carbon Doping Effect on VTHDrift and Dynamic-RON of 100V p-GaN Gate AlGaN/GaN HEMTs

The effect of the GaN buffer doping on VTH drift and dynamic-RON of 100 V p-GaN gate AlGaN/GaN HEMTs is investigated in this work. Devices presenting two different Carbon (C) concentrations in the GaN buffer layer are characterized by means of vertical leakage, back-bias stress and off-state stress measurements. Back-bias stress on TLM structures is used to highlight the dynamics associated to C-related buffer acceptors. A significant difference is observed between samples with different C-doping, that correlates well with the different RON - degradation observed under conventional off-state stress conditions. Better V TH and RON stability is observed on samples with less insulating buffer, highlighting the trade-off between leakage and dynamic performances of GaN power devices.