Highly efficient blue InGaN nanoscale light-emitting diodes

Indium gallium nitride (InGaN)-based micro-LEDs (μLEDs) are suitable for meeting ever-increasing demands for high-performance displays owing to their high efficiency, brightness and stability^1-5. However, μLEDs have a large problem in that the external quantum efficiency (EQE) decreases with the size reduction^6-9. Here we demonstrate a blue InGaN/GaN multiple quantum well (MQW) nanorod-LED (nLED) with high EQE. To overcome the size-dependent EQE reduction problem^8,9, we studied the interaction between the GaN surface and the sidewall passivation layer through various analyses. Minimizing the point defects created during the passivation process is crucial to manufacturing high-performance nLEDs. Notably, the sol-gel method is advantageous for the passivation because SiO₂ nanoparticles are adsorbed on the GaN surface, thereby minimizing its atomic interactions. The fabricated nLEDs showed an EQE of 20.2 ± 0.6%, the highest EQE value ever reported for the LED in the nanoscale. This work opens the way for manufacturing self-emissive nLED displays that can become an enabling technology for next-generation displays.