Temperature-dependent characteristics and mechanisms in thin-barrier AlGaN/GaN MIS-HEMTs with LPCVD-SiN passivation layer

Abstract

This paper investigates the temperature-dependent characteristics and degradation mechanisms of thin-barrier AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors with low-pressure chemical vapor deposition SiN passivation layers on silicon substrate from 223 to 463 K. The channel current degradation in large gate-length devices is primarily attributed to mobility degradation. Through temperature-dependent field-effect mobility analysis, polar optical phonon scattering mechanism dominates at high temperatures, with an extracted optical phonon energy of 92.65 meV. Besides, the mechanisms of gate leakage current were studied. At temperatures above 373 K, slight increased gate leakage after pinch-off is dominated by two-dimensional variable range hopping, with the activation energy of 0.018 to 0.013 eV. While in the reverse bias region, trap-assisted tunneling (TAT) and Poole–Frenkel (PF) emission mechanism were found to dominate. The PF mechanism prevails above 403 K with a trap activation energy of 0.64 eV, while TAT dominates below 298 K showing the trap energy of 0.215 to 0.242 eV. In the medium forward bias region, defect-assisted tunneling (DAT) is the dominant mechanism. In the high forward bias region, TAT dominates with the trap energy ranging from 0.237 to 0.265 eV.