Analysis of Threshold Voltage Instability under Semi-ON Hot Electron Stress in AlGaN/GaN High Electron Mobility Transistor

This work studies the threshold voltage (VT) degradation mechanism of hot electron stress (HES) under semi-ON conditions in AlGaN/GaN high electron mobility transistors (GaN HEMTs). The drain current and drain voltage (ID-VD) transfer curves indicate that kink phenomenon will occur in the semi-ON regime. A long-term HES under conditions where the kink occurs illustrate that the degradation of the ID is caused by a VT shift. From the stress and recovery in HES under different conditions, it can be determined that the hole generation and pre-existing buffer traps recombination play a very important role. Silvaco simulation is also used to simulate the impact of different buffer trap positions on the ID-VG characteristic. Finally, a complete HES mechanism under the semi-ON regime is presented to explain the threshold voltage (VT) degradation.