Analysis of the Extraction Method and Mechanism of Hot Carrier Degradation in Al2O3/Si3N4 Bilayer Gate Dielectric AlGaN/GaN MIS-HEMTs

High-electron-mobility transistor (HEMT) based on Gallium Nitride (GaN) material is often designed for high-voltage operating conditions because of the high electric critical field of GaN material. However, such devices are often prone to the hot carrier stress (HCS) effect under high drain voltage and on-state conditions. Therefore, the HCS effect is an important consideration for reliable GaN HEMT devices. The Al2O3/Si3N4 bilayer gate dielectric AlGaN/GaN metal–insulator–semiconductor (MIS) HEMT has many advantages such as low gate leakage current and interface defects. However, the degradation phenomena observed in this device under HCS is very different from those of Si3N4 MIS HEMTs discussed in several reported studies. In this work, the HCS degradation results of Si3N4 MIS HEMTs and Al2O3/Si3N4 bilayer MIS HEMTs are both investigated and compared. The HCS degradations in Al2O3/Si3N4 bilayer MIS HEMTs are also examined and illustrated in depth. Finally, different stress voltage conditions of HCS are applied and the C-V measurements are carried out in order to confirm the degradation behaviors of MIS HEMT device.