The internal quantum efficiency (IQE) and the forward voltage characteristics of GaN/InGaN-based blue light-emitting diodes (LEDs) are investigated based on numerical simulations. Specifically, we study the effects of structural parameters near the AlGaN electron-blocking layer (EBL), such as the Al composition of the EBL, the thickness of the GaN last barrier (LB) layer, and the doping concentration at the p-type-doped layers. When the hole concentration is sufficiently high, LEDs without the AlGaN EBL are found to show the best performances in IQE and forward voltage, implying that AlGaN-EBL-free structures can be advantageous for achieving high-efficiency LED characteristics. We also find and discuss the facts that the high hole concentration at the p-layers and the thin LB layer thickness are advantageous for high IQE and low forward voltage characteristics under the condition that the Mg diffusion into the active layers is not significant.
GaN Light-emitting diode Electron-blocking layer Efficiency