Red InGaN micro-LEDs on freestanding substrates

According to a report by Luming Yu et al. published in Applied Physics Letters, Tsinghua University and Beijing National Laboratory for Condensed Matter Physics in China have developed freestanding gallium nitride substrates (FGS) for red indium gallium nitride (InGaN) micro-light-emitting diodes (LEDs) that exhibit high efficiency and uniformity across arrays of devices . The researchers claim that InGaN red micro-LEDs with etching-defined mesa size <5μm have not previously been reported.

In recent times, there has been much effort to achieve high efficiency using indium gallium nitride (InGaN) in the red section of the visible light spectrum, particularly for micron-sized devices used in arrays for micro-displays aimed at augmented-reality and virtual-reality (AR/VR) applications, such as head-up displays (HUDs) in military aircraft pilot helmets..

The advantages of InGaN over the more traditional red LED materials, such as aluminium indium gallium phosphide (AlInGaP), include easier integration with green and blue InGaN LEDs, and better scaling to smaller device sizes due to less migration of carriers to sidewall defects, where recombination tends to be non-radiative.