KAIST-led team develops high-efficiency, ultra-high-resolution red micro-LED display

News: LEDs Korea Advanced Institute of Science and Technology (KAIST) has demonstrated a high-efficiency, ultra-high-resolution red micro-LED display, paving the way for displays that can deliver visuals even sharper than reality. A research team led by professor Sanghyeon Kim of the School of Electrical Engineering, in collaboration with professor Dae-Myeong Geum of Inha University, compound semiconductor manufacturer QSI, and microdisplay/SoC design company Raontech, has developed red micro-LED display technology that achieves ultra-high resolution while significantly reducing power consumption (Park et al, ‘A Monolithic Three-Dimensional Integrated Red Micro-LED Display on Silicon Using AlInP/GaInP Epilayers’, Nature Electronics, 20 January; DOI: 10.1038/s41928-025-01546-4). Using this technology, the team demonstrated a 1700 pixel-per-inch (PPI)-class ultra-high-resolution micro-LED display — approximately 3–4 times higher than the resolution of existing flagship smartphone displays — capable of delivering truly ‘reality-like’ visuals even in VR and AR devices. Picture: Results of red micro-LED performance improvement. Micro-LEDs are self-emissive displays that surpass OLEDs in brightness, lifetime and energy efficiency, but they have faced two major technical challenges. The first is the efficiency degradation of red micro-LEDs, which becomes severe as pixel sizes shrink due to increased energy leakage. The second is the limitation of conventional transfer processes, which rely on mechanically locating and placing microscopic LEDs one by one, making ultra-high-resolution fabrication difficult and increasing defect rates. The research team addressed both challenges simultaneously. First, they adopted an AlInP/GaInP quantum-well structure, enabling highly efficient red micro-LEDs with minimal energy loss even at very small pixel sizes. The quantum-well/barrier structure acts as an energy barrier, confining 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. Also, instead of transferring individual LEDs, the researchers employed a monolithic three-dimensional (3D) integration technique, stacking the LED layers directly on top of the driving circuitry. This approach minimizes alignment errors, reduces defect rates, and enables stable fabrication of ultra-high-resolution displays. The team also developed a low-temperature process to prevent damage to the underlying circuitry during integration. KAIST claims that this achievement is particularly significant because it demonstrates a fully functional, ultra-high-resolution and highly quantum-efficient red micro-LED display, widely regarded as the most difficult component to realize. The technology is expected to find broad applications in next-generation displays where pixel granularity must be virtually imperceptible, including AR/VR smart glasses, automotive head-up displays (HUDs), and ultra-compact wearable devices. Picture: Monolithic 3D micro-LED-on-Si display. “This work simultaneously solves the long-standing challenges of red pixel efficiency and circuit integration in micro-LEDs,” says Kim. “We will continue to advance this technology toward practical commercialization as a next-generation display platform.” The study was led by Dr Juhyuk Park of the KAIST Institute of Information Electronics as first author. The research was supported by the National Research Foundation of Korea Basic Research Program (2019), the Display Strategic Research Laboratory Program (currently ongoing), and the Samsung Future Technology Incubation Center (2020–2023). Red InGaN micro-LED on silicon prospecting microLED www.kaist.ac.kr