Comparative study of hot carrier induced degradation in AlGaN/GaN and InAlGaN/GaN HEMTs with AlN spacer

This article investigates the degradation phenomenon of Y-gate AlGaN/GaN and InAlGaN/GaN high-electron mobility transistors (HEMTs) with AlN spacers under hot carrier injection (HCI) stress. The analysis focused on the degradation of threshold voltage (ΔV_TH), transconductance (G_m), and drain current (I_D) of the devices subject to a 10 000 s HCI stress test. AlGaN/GaN HEMTs showed a ΔV_TH shift of 0.099 V and an 18.26% I_D reduction, while InAlGaN/GaN HEMTs exhibited a slightly larger ΔV_TH shift (0.135 V) but a smaller I_D degradation (13.62%). The difference results from the lattice mismatch from low In doping concentrations but a higher 2DEG density compensates for trap-induced scattering, resulting in improved carrier transport and greater electrical stability. InAlGaN/GaN devices also had much lower transconductance degradation (11 mS mm⁻¹) than AlGaN/GaN devices (56 mS mm⁻¹). The findings underscore the benefits of the AlN spacer and In incorporation in improving polarization, interface quality, and reliability, showing promise for long-term, high-performance applications.