Analysis of Interface Properties in AlGaN/GaN MIS-HEMTs with HfO2 and SiNx Gate Dielectric

In this work, the electrical reliability of AlGaN/GaN MIS-HEMTs with HfO₂ and SiN_x gate dielectric has been investigated. It is found that the device with SiN_x gate dielectric exhibits higher electrical stability than the device with HfO₂ gate dielectric, presenting low threshold voltage drift (ΔV_th) under positive gate bias stress temperature (PBST). Meanwhile, it is observed that the average effective interface barrier energy (E_τ) for the device with HfO₂ and SiN_x gate dielectric is 0.49 eV and 1.03 eV. Correspondingly, compared to the device with HfO₂ gate dielectric, the device with SiN_x gate dielectric has lower channel carriers trapped in the barrier/gate dielectric interface, which agrees with the high electrical stability for AlGaN/GaN MIS-HEMTs with SiN_x gate dielectric under PBST.