Influence of Poly-AlN Passivation on the Performance Improvement of 3-MeV Proton-Irradiated AlGaN/GaN MIS-HEMTs

To improve the performance of AlGaN/GaN high electron mobility transistors (HEMTs) after exposure to high energy irradiation, 4-nm polycrystalline AlN (poly-AlN) film formed by annealing at 850 °C is proposed to passivate the GaN cap layer. After exposure to 3-MeV proton irradiation with a fluence of 3×1014cm-2, the ON-resistances (RON) of AlGaN/GaN MIS-HEMTs with SiNx and poly-AlN passivation increase by 28% and 32%, and the dynamic ON-resistances (Rd,ON) degrade by 2000% and 110% with a 30-V OFF-state and a 5-V ON-state drain bias, respectively. The polarization effect of poly-AlN reduces the energy band of the GaN cap layer and compensates for deep-level surface defects, moreover, the growth of AlN by atom layer deposition with low plasma power make the GaN surface smooth, which contributes to the reliability improvement of AlGaN/GaN HEMTs after the proton-irradiation.