Kookmin University (President Jung Seung-ryul) announced that a research team led by Professor Do Young-rak of the Department of Chemistry has developed a new GaN-based fin-LED chip material and pixel process technology.

Micro-LEDs (Micro-LEDs), which are attracting attention as a next-generation display technology, have garnered much attention for their excellent color reproduction and high energy efficiency. However, the current size of micro-LED chips and pixel assembly methods have been a major obstacle to their popularization due to high chip prices, pixel fabrication costs, and defect rates in the process. Existing pixel assembly technologies, such as stamp printing transfer and laser transfer, suffer from low assembly efficiency, especially as the size of the chip shrinks to 10 μm or less, the defect rate increases when contacting the electrode line, and some transfer technologies suffer from chip damage.

To overcome these limitations, a research team led by Professor Do, Young Rag (Department of Chemistry) at Kookmin University has developed a new GaN-based fin-LED chip material and pixel process technology. The pixel fabrication technology adopts a selective surface-oriented dielectrophoresis (DEP) assembly method to efficiently assemble submicron-sized fin-LEDs. This provides a new possibility to overcome the limitations of existing micro-LED technol

The GaN-based submicron-sized fin-LEDs developed by the Kookmin University research team are designed to maximize performance while minimizing cost. The technology significantly improves the light efficiency by aligning the fin-LEDs in a vertical direction and enables the realization of chip materials and pixel manufacturing processes that significantly reduce production costs. In particular, compared to the nanorod LED previously developed by the Kookmin University research team, the volume of multiple quantum wells is increased by about 8 times with the same volume, which greatly improves the omnidirectional luminous efficiency. The findings are expected to mark a new turning point in the micro LED display industry by dramatically improving the efficiency and performance of high-performance submicro LED assembly technology.

The dielectrophoresis-based assembly method reached a high vertical alignment rate of 91.3% and an outstanding pixel production yield of 99.93%. The team's blue fin-LEDs achieved an external quantum efficiency (EQE) of 9.1% and a brightness of 8,640 cd/m² at 5.0 V, which is comparable to existing technologies despite its early stage. The fin-LEDs can be mass-produced through top-down etching and ultrasonic chemical separation technology, and the wafer utilization rate is stable at over 90%, providing an economical and reliable solution for the display industry.

“We have developed the underlying technology for low-cost, high-performance inorganic light-emitting displays that can be commercialized through pixel fabrication technology that realizes ultra-small, ultra-thin vertical fin-LEDs and vertically aligns them,” said Prof. Do, Young Rag. ”With the advancement of fin-LED material production technology and vertical alignment technology, submicron fin-LEDs will become the core technology for next-generation inorganic light-emitting displays that surpass the limitations of OLEDs and existing micro-LEDs.”

The selective surface-oriented dielectrophoretic assembly method published by the Kookmin University research team is a platform technology that can be used for a variety of applications in the display field. The research was conducted by a joint research team from the Korea Electronics Technology Research Institute, POSTECH, and Kyung Hee University, with Seungje Lee, a PhD student in the Department of Chemistry at Kookmin University, as the first author. The results of the study were published on November 4, 2024 in Nature Communications (JCR top 5.6%, IF 14.7). This research was supported by the Nano and Material Technology Development Project (Strategic) of the National Research Foundation of Korea, the Mid-Career Researcher Support Program, and the Ultra-Large Micro-LED Modular Display Project of the Korea Institute of Industrial Technology (KIT).

Comparison of conventional nanorod LEDs and fin-LEDs

Comparison of field emission characteristics of vertically aligned fin-LEDs