Near‐Complete Elimination of Size‐Dependent Efficiency Decrease in GaN Micro‐Light‐Emitting Diodes

Abstract

Herein, a successful elimination of the size‐dependent efficiency decrease in GaN micro‐light‐emitting diodes (micro‐LEDs) is achieved using damage‐free neutral beam etching (NBE). The NBE technique, which can obtain ultralow‐damage etching of GaN materials, is used in place of the conventional inductively coupled plasma to form the micro‐LED mesa. It is found that all the fabricated micro‐LEDs with sizes ranging from 40 to 6 μm show external quantum efficiency (EQE) versus current density characteristics similar to those of large‐area GaN LEDs, with a maximum in EQE curves at a current density of as low as about 5 A cm−2. Furthermore, all the fabricated micro‐LEDs, even the 6 μm one, show a similar value of maximum EQE with a variation of less than 10%, clearly indicating a negligible size dependence of emission efficiency of micro‐LEDs fabricated by the NBE technique at least down to the size of 6 μm. These results suggest that the NBE process is a promising method of fabricating high‐efficiency sub‐10 μm GaN micro‐LEDs required for high‐efficiency, high‐brightness, and high‐resolution micro‐LED displays.