Hydrogen-passivated AlGaN/GaN HEMTs: fabrication and electrical characterization under-proton irradiation

• Influence of hydrogen passivation on AlGaN/GaN HEMTs under proton irradiation is investigated. • Unpassivated devices exhibit significant degradation, whereas passivated ones show less than 5% change. • Hydrogen atoms effectively neutralize radiation-induced defects and suppress trap activation. • Passivation mitigates contact resistance increase and alleviates Fermi-level pinning at the interface. • This approach offers a robust radiation-hardening strategy for extreme-environment applications. This study quantitatively examines the effect of hydrogen passivation on the electrical degradation of AlGaN/GaN high electron mobility transistors (HEMTs) subjected to proton irradiation. Proton exposure was conducted at an energy of 15 MeV with a fluence of 5 × 10 13 cm −2 , and device characteristics were compared before and after irradiation. Prior to irradiation, performance differences between passivated and unpassivated devices were within 5 %. Following irradiation, unpassivated devices exhibited a 28.4 % reduction in on-current, a greater than 20 % decrease in transconductance (g m ), and a 28 % increase in contact resistance (R c ). In contrast, hydrogen-passivated devices demonstrated stable operation, with less than 5 % degradation in on-current, a 3 % variation in g m , and only a 4 % change in R c . These improvements are attributed to hydrogen atoms neutralizing radiation-induced defects, including donor-like and acceptor-like traps, which otherwise reduce electron mobility and increase contact resistance. By suppressing trap activation and mitigating potential fluctuations and Fermi-level pinning at the AlGaN/GaN interface, hydrogen passivation stabilizes the two-dimensional electron gas (2DEG) density and carrier transport, preserving current conduction and interfacial reliability post-irradiation. Therefore, hydrogen passivation is identified as a critical radiation-hardening strategy that effectively mitigates current degradation and contact instability in AlGaN/GaN HEMTs, providing a robust foundation for the design of GaN power devices for space and other extreme-environment applications.