High Efficiency of 5 μm‐Diameter Blue Micro‐Light‐Emitting Diodes

Abstract

Small‐size pixels and high efficiency under low injection levels are required for high‐resolution microdisplay. Efficient blue InGaN micro‐light‐emitting diodes (μLEDs) with 5 μm diameter are fabricated using AuSn flip‐chip bonding, high reflection electrodes, and large‐area N electrodes surrounding the mesas. The peak external quantum efficiency (EQE) measured in an integrating sphere is as high as 13.67% at a current density of 5.4 A cm−2. Moreover, at a current density of 0.1 A cm−2, EQE can still reach 11.69%. The electrical efficiency approaches 1, and the differential slope of log L versus log I is close to 1 at low current density. These results suggest significant progress in exploring high‐efficiency 5 μm InGaN blue μLEDs.