Simulation Study on the Mechanisms of Proton-Induced Single Event Effects in GaN HEMT

Abstract: This paper constructs a multi-layer structural model of GaN HEMT based on Geant4 to simulate the distributions of mass number $A$, charge number $Z$, kinetic energy $E_k$, and linear energy transfer (LET) of secondary particles reaching the GaN sensitive layer after 10$\sim$500 MeV protons incident in the gate, source-gate gap, and drain regions. The results indicate that when 10$\sim$200 MeV protons are incident on the drain at angles of 0$^{\circ}\sim$60$^{\circ}$, the angular effect is smoothed out in the sensitive layer, with deviations in the average A and Z less than 10\% between angles. This is primarily due to the cumulative attenuation from multiple Coulomb scattering and energy loss in the overlying layers. Furthermore, vertical irradiations on the gate, source-gate gap, and drain regions with protons of different energies reveal that the gate is most sensitive to energy variations, with the proportion of high-LET($>$ 15 MeV~cm$^2$/mg) events increasing from 5\% to 15\%, representing a 200\% increase in the 10$\sim$50 MeV range, attributed to the enhanced nuclear reaction yield by high-Z overlayers; the source-gate gap shows intermediate sensitivity with a change rate of 18\%; and the drain is the least sensitive, only obvious increase in high-LET interval. These quantitative patterns reveal the microscopic influences of overlayer materials and geometric structures on secondary particle transport, providing a physical basis for explaining threshold issues such as SEGR and SEB.