Influence of GaN Stress on Threshold Voltage Shift in AlGaN/GaN High-Electron-Mobility Transistors on Si under Off-State Electrical Bias

摘要

The change in threshold voltage (Vth) in AIGaN/GaN high-electron-mobility transistors (HEMTs) on Si occurs during off-state bias stress.Raman spectroscopy shows that the GaN strain/stress changes with the increase in buffer and i-GaN thicknesses.Our results revealed that there is a strong correlation between the Vth shift and GaN strain/stress.The Vth shifts positively and negatively, respectively, for biaxial tensile and compressive strains.We observed minimal device degradation with the negligible l/th shift before and after off-state bias stress for the strain relieved sample.The results illustrate the importance of GaN strain/stress for the degradation and reliability of AIGaN/GaN HEMTs.