Effects of Gd2O3 Gate Dielectric on Proton-Irradiated AlGaN/GaN HEMTs

AlGaN/GaN high electron mobility transistors (HEMTs) and MOS-HEMTs using Gd
₂
O
₃
as gate dielectric were irradiated with 2-MeV protons up to fluence of 1 × 10
¹⁵
cm
^-2
. Results showed that proton irradiation causes a strong degradation in the Schottky gate devices, featured by more than three orders of magnitude increase in reverse leakage current, a 30% decrease in maximum drain current, and the same percentage of increase in ON-resistance, respectively. Scanning transmission electron microscopy showed that radiation induced a diffusion of Ni into Au in the gate and void formation, degrading the transistors' characteristics. The Gd
₂
O
₃
gate dielectric layer prevented this diffusion and void formation. MOS-HEMTs with Gd
₂
O
₃
gate dielectric show 50% less decrease of performance under proton irradiation than Schottky gate HEMTs (conventional HEMTs). The trapping effects of Gd
₂
O
₃
gate layer before and after irradiation are also discussed.