Performance enhancement of blue light-emitting diodes with AlGaN barriers and a special designed electron-blocking layer

Abstract

In this study, the characteristics of the nitride-based blue light-emitting diode (LED) with AlGaN barriers are analyzed numerically and experimentally. The emission spectra, carrier concentrations in the quantum wells (QWs), energy band diagrams, electrostatic fields, and internal quantum efficiency are investigated. The results indicate that the LED with AlGaN barriers has a better hole-injection efficiency and an enhanced carrier confinement in its active region over the conventional counterpart with GaN barriers. The results also show that the AlGaN electron-blocking layer (EBL) with a gradual variation of Al mole fraction has a significantly enhanced electron blocking capability as well as a greatly improved hole-injection efficiency. When Al0.08Ga0.92N QW barriers and the special designed EBL are used, the electroluminescence emission intensity is increased greatly by 69% at 200 A/cm2 and the efficiency droop is reduced markedly to 8.7% from 85% at 400 A/cm2 compared with those of the conventional LED.