Novel insights into GaN-HEMT behaviour under multi-particle irradiation

This study investigates the effects of photon, neutron, and $\alpha$-irradiation on the electrical characteristics of a 30 A GaN-HEMT (Gallium Nitride High Electron Mobility Transistor). Photon irradiation leads to a noticeable decrease in the drain current ($I_D$) across all gate voltages, with nonlinear deviations increasing with gate voltage. This phenomenon is attributed to photon-induced $\delta$-rays, which generate crystal defects and alter the band structure. Neutron irradiation primarily causes a significant shift in the saturation region of the $I_D$-$V_D$ characteristics, highlighting unique interactions through neutron capture reactions and scattering events. $\alpha$-particles induce combined atomic, nuclear, and $\delta$-ray effects, along with heating. The lack of significant shifts in knee voltage across different irradiations indicates that damage primarily affects the crystal lattice and electron transport mechanisms without altering fundamental operational thresholds. A quantum mechanical methodology is devised to elucidate the physics underlying radiation stress measurements, focusing on displacement damage, radiation-induced transmutation doping effects, and the significance of radiation-induced reactions within the device.