Proton-Irradiation Effects and Reliability on GaN-Based MIS-HEMTs

A comprehensive study of proton irradiation reliability on a bilayer dielectrics SiN_x/Al₂O₃ MIS-HEMT, the common Schottky gate HEMT, and a single dielectric layer MIS-HEMT with SiN_x and with Al₂O₃ for comparison is conducted in this paper. Combining the higher displacement threshold energy of Al₂O₃ with the better surface passivation of the SiN_x layer, the bilayer dielectrics MIS-HEMT presents much smaller degradation of structural materials and of device electrical performance after proton irradiation. Firstly, the least of the defects caused by irradiation suggesting the smallest structural material degradation is observed in the bilayer dielectrics MIS-HEMT through simulations. Then, DC and RF electrical performance of four kinds of devices before and after proton irradiation are studied through simulation and experiments. The smallest threshold voltage degradation rate, the smallest maximum on-current degradation and Gm degradation, the largest cut-off frequency, and the lowest cut-off frequency degradation are found in the bilayer dielectrics MIS-HEMT among four kinds of devices. The degradation results of both structural materials and electrical performance reveal that the bilayer dielectrics MIS-HEMT performs best after irradiation and had better radiation resilience.