Improvement of Efficiency Droop in Blue InGaN Light-Emitting Diodes With p-InGaN/GaN Superlattice Last Quantum Barrier

The blue InGaN light-emitting diodes (LEDs) with specific designs of p-InGaN/GaN superlattice (SL) last quantum barrier are investigated numerically and experimentally. The proposed SL with a graded indium mole fraction from 0% to 5% shows improved efficiency droop and superior optical characteristics in comparison with the conventional LEDs. As indicated by the simulation results, the promotion of hole injection and the reduction of electron leakage play important roles in these improvements. Fabricated LEDs with this specific design exhibit stronger emission intensity, smaller forward voltage, and larger light output power compared to its counterparts.