Irradiation Hardening of p-GaN HEMT Based on AlN Polarization Regulation Mechanism

In this article, an irradiation-hardened p-GaN high electron mobility transistor (HEMT) based on the AlN polarization effect (A-HEMT) was proposed. First, before irradiation, the AlN polarization effect assists the gate in regulating the channel, enhances the charge sharing in the GaN layer, and suppresses the drain-induced barrier lowering (DIBL) effect. Second, after passivating the gate etched surface with the AlN strain layer, the electron trap density at the AlGaN/GaN interface decreased from $7.69\times 10^{18}$ to $8.66\times 10^{17}$ /(eV $\cdot $ cm2). The hole trap density at the p-GaN/AlGaN interface decreased from $3.0\times 10^{18}$ to $5.21\times 10^{17}$ /(eV $\cdot $ cm2), and the trap energy level became shallower from 0.289 to 0.281 eV. As a result of the mitigated gate trap effect, after 300 and 500 krad(Si) on-state irradiation, the gate Schottky barrier and the ideality factor of A-HEMT were less degraded. Furthermore, the post-irradiation carrier transport model of the A-HEMT gate-stack was proposed. Third, the optimized electric field modulated by AlN polarization in the device drift region can effectively shield the charge generated by the on-state irradiation. After a 500 krad(Si) dose, the A-HEMT has a smaller ${V}_{\text {th}}$ drift and a smaller ${R}_{\text {dson}}$ variation. The channel electric field in the A-HEMT was about 1.6 times lower than that of the conventional HEMT (C-HEMT). The measured capacitance showed that the AlN strain layer can reduce the traps induced by on-state irradiation in the active region of the device. Therefore, the AlN strain layer is a feasible irradiation hardening method.