Impact of Sidewall Conditions on Internal Quantum Efficiency and Light Extraction Efficiency of Micro‐LEDs

The sidewall condition is a key factor determining the performance of micro-light emitting diodes (µLEDs). In this study, equilateral triangular III-nitride blue µLEDs are prepared with exclusively m-plane surfaces to confirm impact conditions. It found that inductively coupled plasma-reactive ion etching (ICP-RIE) causes surface damages and results in rough morphology. As confirmed by time-resolved photoluminescence (TRPL) X-ray photoemission spectroscopy (XPS), tetramethylammonium hydroxide (TMAH) eliminates damage flattens surface. After ICP-RIE, 100 µm2-µLEDs yield higher external quantum efficiency (EQE) than 400 µm2-µLEDs. However, after TMAH treatment, peak EQE increases ≈10% low current regime, whereas slightly decreases ≈3%. treatment although internal (IQE) increases. Further, IQE before insignificant at temperatures below 150 K, above which it becomes considerable. Based on PL, XPS, scanning transmission electron microscopy, microscopy results, mechanisms for size dependence explained terms non-radiative recombination rate light extraction.