Effect of InAlGaN Interlayers on the Efficiency of InGaN-Based Red Light-Emitting Diodes

We report on a numerical study of the effect of InAlGaN interlayers on the efficiency of InGaN‑based red light-emitting diodes (LEDs). The introduction of interlayers in red LED structures was found to increase the turn-on voltage from approximately 2.64 V (without interlayer) to 2.68, 3.05, and 3.08 V for devices incorporating GaN, Al0.20Ga0.80N, and partially strain-relaxed In0.08Al0.35Ga0.57N interlayers, respectively. Among the four LED configurations studied, the structure with an In0.08Al0.35Ga0.57N interlayer exhibited the best performance, emitting at 632 nm with an internal quantum efficiency of 0.67, an external quantum efficiency of 33.5%, and a wall-plug efficiency of 21.2%. The partially strain-relaxed In0.08Al0.35Ga0.57N interlayer effectively modifies the band structure by increasing electron and hole barrier heights, enhancing carrier confinement, and reducing polarization-induced fields. Furthermore, this device demonstrated superior stability of the electroluminescence peak wavelength under increasing bias voltage compared to the other structures.