From TVs and smartwatches to the recently highlighted VR/AR devices—micro-LED, the core technology of these screens, is a next-generation display where individual LEDs smaller than the thickness of a human hair emit light on their own. While Red, Green, and Blue (RGB) are essential for completing a display, highly quantum efficient red micro-LED technology is known to be the most difficult to implement. Professor Sanghyeon Kim of our department and his joint research team have overcome the limitations of existing technologies. They have developed a red micro-LED display technology that achieves ultra-high resolution while significantly reducing power consumption.
Through this, the research team successfully implemented a 1,700 PPI-level ultra-high-resolution micro-LED display. This technology can provide ‘real-life-like images’ rather than just high-resolution screens for VR/AR devices, offering approximately 3 to 4 times the resolution of current smartphone displays. *PPI (Pixel Per Inch): An index indicating how densely pixels, the smallest dots forming a screen, are arranged.
There were two main challenges in commercializing micro-LEDs. First was the efficiency degradation of red LEDs. Specifically, when implementing ‘red pixels,’ energy leakage occurs as the pixel size decreases, causing efficiency to drop sharply. Second was the limitation of the transfer process. The conventional method of picking and placing millions of microscopic LEDs individually makes ultra-high resolution difficult and leads to high defect rates.
The research team solved these problems simultaneously. First, by applying an AlInP/GaInP ‘double-quantum-well (DQW) structure’, they implemented high-efficiency red micro-LEDs that significantly reduce energy loss even as pixel sizes shrink. Simply put, the quantum well/barrier structure acts as an “energy barrier.” It confines electrons and holes within the quantum well layer, preventing carrier leakage. By adopting quantum wells with higher hole concentration, the research team effectively reduced energy loss as pixel sizes decreased, enabling brighter and more efficient red micro-LEDs
Furthermore, instead of transferring LEDs individually, they applied ‘monolithic three-dimensional (M3D) integration’ technology. This involves stacking the LED layers directly onto the driving circuits. This method has the advantage of reducing alignment errors and defect rates, allowing for the stable production of ultra-high-resolution displays. During this process, the research team also secured low-temperature process technology to prevent damage to the underlying circuits.
This research, led by Dr. Juhyuk Park (KAIST) as the first author and Professor Sanghyeon Kim (KAIST) and Professor Dae-Myeong Geum (Inha University) as corresponding authors, was published in the world-renowned academic journal ‘Nature Electronics’ on January 20.
※ Paper Title: A monolithic three-dimensional integrated red micro-LED display on silicon using AlInP/GaInP epilayers)
※ URL: https://www.nature.com/articles/s41928-025-01546-4
The research was conducted in collaboration with Professor Dae-Myeong Geum of Inha University. The team also partnered with QSI (CEO Chung-dae Lee), a compound semiconductor manufacturer, and RAONTECH (CEO Seung-tak Yi), a micro-display and semiconductor SoC design company. This work was supported by the National Research Foundation of Korea (NRF) Basic Research Program (2019) and the Display Strategy Research Laboratory project (currently ongoing). It also received support from the Samsung Science and Technology Foundation (2020–2023).
