Neutron Irradiation Impact on AlGaN/GaN HEMT Switching Transients

Current transient spectroscopy was used to measure the impact of neutron irradiation on output current-limiting charge traps in AlGaN/GaN high electron mobility transistors with time constants from 10 ms to 1800 s. We find that coupling between discrete traps was apparent, in contrast to the commonly employed assumption of independent trap (dis)charging, and increased after 14-MeV neutron irradiation of 2 \times 10^{13}\,\,\text {n/cm}^{2} and above. Irradiation to a high dose of as much as 7.8 \times 10^{14}\,\,\text {n/cm}^{2} , which is comparable to eight years exposure to a harsh radiation environment, such as the International Thermonuclear Experimental Reactor neutral-beam injector prototype, increased trapped charge density and reduced transient drain current to as little as 75% of its equilibrium value. These changes are consistent with displacement damage estimates based on the radiation transport calculations.