Significant Degradation of AlGaN/GaN High-Electron Mobility Transistors With Fast and Thermal Neutron Irradiation

The AlGaN/GaN high-electron mobility transistors (HEMTs) were irradiated with fast and thermal neutrons at various fluences. Output, transfer, and gate-leakage characteristics were analyzed in detail before and after irradiation. After irradiation by 14-MeV neutrons, the electrical characteristics of the devices gradually degraded as the fluence increased. After irradiation by thermal neutrons at a fluence of 2.12×10
¹⁶
cm
^-2
, the electrical characteristics of devices significantly decreased. Neutrons are believed to introduce a negatively charged acceptorlike deep level in the AlGaN layer, which can deplete 2DEG in the channel, raise the energy band, and shift the threshold voltage to positive values. Such an enhanced barrier can significantly suppress the gate Schottky leakage current of AlGaN/GaN HEMTs in both the reverse and forward bias regions. After the thermal neutron radiation, the quality of Schottky contacts deteriorated significantly.