Wafer-Scale Monolithic Integration of Blue Micro-Light-Emitting Diodes and Green/Red Quantum Dots for Full-Color Displays
Feifan Xu, Tao Tao, Dongqi Zhang, Yang Zhang, Yimeng Sang, Junchi Yu, Ting Zhi, Zhe Zhuang, Zili Xie, Rong Zhang, Bin Liu
Abstract
We demonstrated a simple method for achieving green and red colors by patterning quantum dots (QDs) on GaN-based blue micro-light-emitting diodes ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs) using standard photolithography and dry etching process. The QDs could be patterned as small as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 ~\mu \text{m}$ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs in a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10\,\,\mu \text{m}\,\,\times 10\,\,\mu \text{m}$ </tex-math></inline-formula> 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) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs as a single pixel by sequentially patterning red and green QDs. The color gamut of the RGB <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2~\mu \text{m}$ </tex-math></inline-formula> -size-resolution and achieving high performance for red/green <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs, while enabling scalable fabrication of full-color <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LED displays.