Threshold Voltage Instability Mechanisms in p-GaN Gate AlGaN/GaN HEMTs

In this study, we propose a technique to evaluate the transient threshold voltage behavior of p-GaN capped AlGaN/GaN high-electron-mobility transistors (HEMTs). The threshold voltage is monitored from 10 μs to 100 s during positive gate bias stress. Technology computer-aided design (TCAD) simulations offer in-depth analysis of the different threshold voltage instability mechanisms: (i) electron trapping at the AlGaN/GaN interface, (ii) hole accumulation and trapping at the p-GaN/AlGaN interface and in the AlGaN barrier, respectively, and (iii) hole depletion of the p-GaN layer.