Gate leakage mechanisms in Al₂O₃/SiN/AlN/GaN MIS-HEMTs on Si substrates

This study investigates the gate leakage mechanisms of AlN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) fabricated on silicon substrate with Al₂O₃/SiN as stacked gate dielectrics, analyzing behaviors across high and low temperature conditions. In the high-temperature reverse bias region (T > 275 K, V_G < 0 V), Poole–Frenkel emission (PFE) dominates at low electric fields, while trap-assisted tunneling (TAT) is the primary mechanism at medium to high electric fields. The shift from PFE to TAT as the dominant conduction mechanism is due to the increased tunneling effect of electrons as the electric field strength rises. Additionally, TAT is found to be the main gate leakage mechanism under low-temperature reverse bias (T < 275 K, V_G < 0 V). At lower temperatures, the reduction in electron energy causes the emission process to rely more on electric field forces. Furthermore, under forward bias conditions at both high and low temperatures (225 K < T < 375 K, V_G > 0 V), conduction is primarily dominated by defect-assisted tunneling (DAT).