Luminescence efficiency improvement of small-size micro light-emitting diodes by a digital etching technology

The decrease of light output efficiency with the reduction of LED (light-emitting diode) die size is one of the challenges of micro-LED displays. Here we propose a digital etching technology that employs multi-step etching and treatment to mitigate sidewall defects exposed after mesa dry etching. In this study, by two-step etching and N₂ treatment, the electrical properties of the diodes show an increase of forward current and a decrease in reverse leakage due to suppressed sidewall defects. An increase of light output power by 92.6% is observed for 10 × 10-µm² mesa size with digital etching, as compared with that with only one step etching and no treatment. We also demonstrated only 1.1% decrease in output power density for a 10 × 10-µm² LED as compared with a 100 × 100-µm² device without performing digital etching.