1.5 × 1.5 μm2GaN green micro-LEDs fabricated using high-rate neutral beam etching exhibited 32% external quantum efficiency.

Neutral beam etching (NBE) has been demonstrated to be the only technique that enables damage-free fabrication of GaN blue micro-light-emitting diodes (micro-LEDs) down to sizes of a few microns. An enhancement in etching rate is strongly required for the NBE technique to be adopted as a mass-production process for GaN micro-LEDs. Herein, we report on the damage-free fabrication of GaN green micro-LEDs down to a size as small as 1.5 × 1.5 μm2 at an etching rate (~12.1 nm/min) more than twice as fast as that in previous experiments (~5 nm/min). This is achieved by optimizing the bias power applied to the carbon aperture plate of the NBE system. A 1.5 × 1.5 μm2 micro-LED fabricated at an etching rate of 12.1 nm/min exhibited a record-high maximum external quantum efficiency of 32%. This result represents a significant step toward establishing the NBE technique as a mass-production process for GaN micro-LEDs down to the micron-size range.