630-nm red InGaN micro-light-emitting diodes (<20 μm × 20 μm) exceeding 1 mW/mm2 for full-color micro-displays

1 min read · Tue, Jul 20 2021

The paper reports InGaN-based RGB micro-LED arrays that comprise every single µLED in the dimension of 17 × 17 µm2. We obtained the output power density of the InGaN-based red µLEDs as 1.76 mW/mm2, which was estimated to be higher than that of 20 × 20 µm2 AlInGaP red µLEDs (~630 nm). The result reveals a great potential for the InGaN materials to be used in full-color micro-displays.

We demonstrate 10 × 10 arrays of indium gallium nitride (InGaN) 17 × 17 µm2 micro-light-emitting diodes (µLEDs) operated at high current densities. The µLED array exhibits a peak wavelength from 662 to 630 nm (32-nm blue-shift) at 10 to 50 A/cm2. The on-wafer external quantum efficiency increases with the current density and reaches 0.18% at 50 A/cm2. We also obtained the output power density of the red µLEDs as 1.76 mW/mm2, which was estimated to be higher than that of 20 × 20 µm2 aluminum indium gallium phosphide (AlInGaP) red µLEDs (~630 nm). By fabricating InGaN blue and green µLED arrays, we finally demonstrate that InGaN red, green, and blue µLEDs can exhibit a wide color gamut covering 81.3% and 79.1% of the Rec. 2020 color space in the International Commission of Illumination (CIE) 1931 and 1976 diagrams, respectively. These results reveal a great potential for the InGaN materials to be used in full-color micro-displays.