Wafer-Scale Monolithic Integration of Blue Micro-Light-Emitting Diodes and Green/Red Quantum Dots for Full-Color Displays

We demonstrated a simple method for achieving green and red colors by patterning quantum dots (QDs) on GaN-based blue micro-light-emitting diodes ( $\mu $ LEDs) using standard photolithography and dry etching process. The QDs could be patterned as small as $2 ~\mu \text{m}$ in size on a 4-inch wafer, revealing the ultra-high resolution and throughput capability of this method. The individual color-converted green and red $\mu $ LEDs in a size of $10\,\,\mu \text{m}\,\,\times 10\,\,\mu \text{m}$ exhibited a peak external quantum efficiency (EQE) of 9.6% and 14.7%, respectively. We also achieved the monolithic integration of red, green, and blue (RGB) $\mu $ LEDs as a single pixel by sequentially patterning red and green QDs. The color gamut of the RGB $\mu $ LEDs covered 83.4% of the Rec. 2020 color space in the CIE 1931 diagram. This method is very effective for patterning color-converted QDs with down to $2~\mu \text{m}$ -size-resolution and achieving high performance for red/green $\mu $ LEDs, while enabling scalable fabrication of full-color $\mu $ LED displays.