Radiation-Tolerant RF Performance Enhancement of AlxGa1-xN Graded Composite Barrier GaN HEMTs for Radio Astronomy Applications

This study investigates the design and radiation resistance of an AlxGa1-xN graded composite barrier GaN high-electron-mobility transistor (GB-HEMT) compared to a conventional fixed-barrier GaN HEMT (FB-HEMT). Using Silvaco TCAD simulations, the GB-HEMT demonstrates a wider 2DEG channel and flatter transconductance (gm) profile, resulting in a saturation drain current of 1.73 A/mm², significantly improved turn-off characteristics, and superior RF performance. Specifically, the GB-HEMT achieves a peak power-added efficiency (PAE) of 44.4%, a gain of 18.7 dB, and a power density of 3.8 W/mm under large-signal operation. Furthermore, proton irradiation simulations (1.8 MeV protons) reveal that the GB-HEMT exhibits reduced DC parameter degradation compared to the FB-HEMT, highlighting its enhanced radiation tolerance. The results suggest that the GB-HEMT is a promising candidate for millimeter-wave power amplifiers in extreme environments such as radio astronomy.