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KAIST Overcomes Limitations of Existing Image Sensors… Clear Colors Even Under Oblique Light
<(From Left) Ph.D candidate Chanhyung Park from Electrical Engineering, Jaehyun Jeon from Department of Physics, Professor Min Seok Jang from Electrical Engineering>
Smartphone cameras are becoming smaller, yet photos are becoming sharper. Korean researchers have elevated the limits of next-generation smartphone cameras by developing a new image sensor technology that can accurately represent colors regardless of the angle at which light enters. The team achieved this by utilizing a “metamaterial” that designs the movement of light through structures too small to be seen with the naked eye.
KAIST (President Kwang Hyung Lee) announced on the 12th of February that a research team led by Professor Min Seok Jang of the School of Electrical Engineering, in collaboration with Professor Haejun Chung’s team at Hanyang, has developed a metamaterial-based technology for image sensors that can stably separate colors even when the angle of light incidence varies.
Conventional smartphone cameras capture images by concentrating light into a small lens. However, as camera pixels become extremely small, lenses alone struggle to gather sufficient light. To address this, the Nanophotonic Color Router was introduced. Instead of concentrating light through a lens, this technology uses microscopic structures invisible to the eye to precisely separate incoming light by color. By designing the pathways through which light travels, this metamaterial-based structure accurately divides light into red (R), green (G), and blue (B).
Samsung Electronics has already demonstrated the commercialization potential of this technology by applying it to actual image sensors under the name “Nano Prism.” Theoretically, stacking multiple layers of extremely fine nanostructures enables greater light collection and more accurate color separation.
<Nanophotonic color router technology that works reliably even under oblique incidence conditions (AI-generated image)>
However, existing Nanophotonic Color Routers had limitations. While they functioned well when light entered vertically, their performance deteriorated significantly—or colors mixed—when light entered at an angle, as is common in smartphone cameras. This issue, known as the “oblique incidence problem,” has been considered a critical challenge that must be resolved for real-world product applications.
The research team first investigated the root cause of this issue. They found that previous designs were overly optimized for vertically incident light, causing performance to drop sharply even with slight changes in the angle of incidence. Since smartphone cameras receive light from various angles, maintaining performance under angular variation is essential.
Instead of manually designing the structure, the team adopted an “inverse design” approach, which allows the computer to autonomously determine the optimal structure. Through this method, they derived a color router design capable of stable color separation even when the angle of incoming light changes.
As a result, whereas previous structures nearly failed when light was tilted by about 12 degrees, the newly designed structure maintained approximately 78% optical efficiency within a ±12-degree range, demonstrating stable color separation performance. In other words, the technology reaches a level suitable for practical smartphone usage environments.
<Nanophotonic color router robust to oblique incidence>
The team further analyzed performance variations by considering factors such as the number of metamaterial layers, design conditions, and potential fabrication errors. They also systematically defined the limits of robustness against changes in the angle of incidence. This study is particularly meaningful in that it presents design criteria for color routers that reflect realistic image sensor environments.
Professor Min Seok Jang of KAIST stated, “This research is significant in that it systematically analyzes the oblique incidence problem, which has hindered the commercialization of color router technology, and proposes a clear solution direction,” adding, “The proposed design methodology can be extended beyond color routers to a wide range of metamaterial-based nanophotonic devices.”
In this study, KAIST undergraduate student Jaehyun Jeon and doctoral candidate Chanhyung Park participated as co-first authors. The research findings were published on January 27 in the international journal Advanced Optical Materials.
※ Paper title: “Inverse Design of Nanophotonic Color Router Robust to Oblique Incidence”
DOI: https://doi.org/10.1002/adom.202501697※ Authors: Jaehyun Jeon (KAIST, first author), Chanhyung Park (KAIST, first author), Doyoung Heo (KAIST), Haejun Chung (Hanyang University), Min Seok Jang (KAIST, corresponding author)
This research was supported by the Ministry of Trade, Industry & Energy (Korea Institute for Advancement of Technology, Korea Semiconductor Research Consortium) under the project “Design Technology of Meta-Optical Structures for Next-Generation Sensors,” by the Ministry of Science and ICT (National Research Foundation of Korea) under the projects “Development of Full-Color Micro LED Devices and Panels Based on Beam-Steerable High-Color-Purity Meta Color Conversion Layers” and “Development of a Real-Time Zero-Energy Argos-Eye Metasurface Network Computing with All Properties of Light,” and by the Ministry of Culture, Sports and Tourism (Korea Creative Content Agency) under the project “International Joint Research for Next-Generation Copyright Protection and Secure Content Distribution Technologies.”
2026.02.19 View 2358 -
KAIST Uses Sandpaper to Polish Semiconductors… Opening a New Path for AI Semiconductor Processing
<(From Left) Dr. Sukkyung Kang, Professor Sanha Kim from Department of Mechanical Engineering>
The performance and stability of smartphones and artificial intelligence (AI) services depend on how uniformly and precisely semiconductor surfaces are processed. KAIST researchers have expanded the concept of everyday “sandpaper” into the realm of nanotechnology, developing a new technique capable of processing semiconductor surfaces uniformly down to the atomic level. This technology demonstrates the potential to significantly improve surface quality and processing precision in advanced semiconductor processes such as high-bandwidth memory (HBM).
KAIST (President Kwang Hyung Lee) announced on the 11th of February that a research team led by Professor Sanha Kim of the Department of Mechanical Engineering has developed a “nano sandpaper” that utilizes carbon nanotubes—tens of thousands of times thinner than a human hair—as abrasive materials. This technology enables more precise surface processing than existing semiconductor manufacturing processes, while also reducing environmental burdens generated during fabrication, presenting a new planarization technique.
< Nano Sandpaper AI-Generated Image >
Although sandpaper is a familiar tool used to smooth surfaces by rubbing, it has been difficult to apply it to fields such as semiconductors, where extremely precise surface processing is required. This limitation arises because conventional sandpaper is manufactured by attaching abrasive particles with adhesives, making it difficult to uniformly secure extremely fine particles.
To overcome such limitations, the semiconductor industry has adopted a planarization process known as chemical mechanical polishing (CMP), which uses a chemical slurry in which abrasive particles are dispersed in liquid. However, this method requires additional cleaning steps and generates large amounts of waste, making the process complex and environmentally burdensome.
To address these issues, the research team extended the concept of sandpaper to the nanoscale. By vertically aligning carbon nanotubes, fixing them inside polyurethane, and partially exposing them on the surface, they implemented a “nano sandpaper.” This structure structurally suppresses abrasive detachment, eliminating concerns about surface damage and maintaining stable performance even after repeated use.
The nano sandpaper developed in this study achieves an abrasive density approximately 500,000 times higher than that of the finest commercially available sandpaper. The precision of sandpaper is expressed in terms of “abrasive density (grit number),” which indicates how densely abrasive particles are arranged on the surface. While everyday sandpaper typically ranges from 40 to 3000 grit, the nano sandpaper exceeds 1,000,000,000 grit. Through this extremely dense structure, surfaces could be processed with precision down to several nanometers—equivalent to the thickness of only a few atoms.
The effectiveness of the nano sandpaper was confirmed through experiments. Rough copper surfaces were polished to a smoothness at the nanometer level, and in semiconductor pattern planarization experiments, the technique reduced dishing defects by up to 67% compared with conventional CMP processes. Dishing defects refer to the phenomenon in which the center of interconnect lines becomes recessed, a major defect affecting the performance and reliability of advanced semiconductors such as HBM.
In particular, because the abrasive materials are fixed on the sandpaper surface, the technology does not require continuous supply of slurry solutions as in conventional processes. This reduces cleaning steps and eliminates waste slurry, presenting the possibility of transitioning semiconductor manufacturing toward more environmentally friendly processes.
< Nano Sandpaper Schematic Diagram >
< Detailed Image of Nano Sandpaper >
The research team expects that this technology can be applied to advanced semiconductor planarization processes such as HBM used in AI servers, as well as to hybrid bonding processes, which are gaining attention as next-generation semiconductor interconnection technologies. The study is also significant in that it expands the everyday concept of sandpaper into nano-precision processing technology, suggesting the possibility of securing core technologies required for semiconductor manufacturing.
Professor Sanha Kim stated, “This is an original study demonstrating that the everyday concept of sandpaper can be extended to the nanoscale and applied to ultra-fine semiconductor manufacturing,” adding, “We hope this technology will lead not only to improved semiconductor performance but also to environmentally friendly manufacturing processes.”
In this study, Dr. Sukkyung Kang of the Department of Mechanical Engineering participated as the first author. The research was recognized for its excellence by receiving the Gold Prize (1st place) in the Mechanical Engineering Division at the 31st Samsung Human Tech Paper Award, hosted by Samsung Electronics. The findings were published online on January 8, 2026, in the international journal Advanced Composites and Hybrid Materials (IF 21.8).
※ Paper title: “Carbon nanotube sandpaper for atomic-precision surface finishing”
DOI: https://doi.org/10.1007/s42114-025-01608-3
This research was supported by the National Research Foundation of Korea (Mid-Career Researcher Program; Ministry of Science and ICT, NRF, RS-2025-00560856), the Glocal Lab Program (Ministry of Education, NRF, RS-2025-25406725), the InnoCORE Program (Ministry of Science and ICT, NRF, N10250154), and the KAIST Up Program.
2026.02.11 View 2381 -
KAIST Extends Its Deepest Condolences on the Passing of the Late Chairman Chang Sun Jung, Founder of Jungheung Group
KAIST extends its deepest condolences on the passing of the late Chairman Chang Sun Jung, founder of Jungheung Group.
Chairman Jung made significant contributions to the development of Korea’s construction industry and regional economy, and was a visionary leader who deeply recognized and actively supported the importance of nurturing science and technology talent. In particular, through his generous contribution to the KAIST Development Fund, he left a meaningful legacy in fostering future scientific talent and advancing research environments that will shape the nation’s future.
KAIST honors Chairman Jung’s noble spirit of giving and dedication, and will continue to strive to ensure that his vision lives on through the advancement of science and technology in Korea.
We extend our sincere condolences to the bereaved family and to the executives and employees of Jungheung Group, and pray for the eternal rest of the deceased.
2026.02.03 View 1399 -
KAIST Proposes a New Dementia Treatment Strategy by Repositioning Molecules without Changing Their Chemical Composition
<(Back row, from left) Professor Mi Hee Lim, Professor Mingeun Kim, Student Jimin Lee, Student Chanju Na, (Upper Right) Dr. Chul-Ho Lee, Dr Kyoung-Shim Kim>
Conventional treatments of Alzheimer’s disease, one of the most common forms of dementia, have been largely focused on targeting individual pathological features. However, Alzheimer’s disease is a multifactorial disorder driven by multiple, tightly interconnected processes, rendering single-target therapeutic approaches inherently limited. Addressing this challenge, KAIST researchers propose a new strategy that enables the simultaneous regulation of multiple disease-inducing factors simply by rearranging the structural positions of drug candidate molecules without altering their chemical substituents.
KAIST (President Kwang Hyung Lee) announced on January 22 that a research team led by Professor Mi Hee Lim of the Department of Chemistry, in collaboration with Professor Mingeun Kim of Chonnam National University, Dr. Chul-Ho Lee of the Korea Research Institute of Bioscience and Biotechnology (KRIBB), and Dr. Kyoung-Shim Kim of the Laboratory Animal Resource Center, has elucidated at the molecular level how subtle differences in molecular arrangement, specifically positional isomerism, give rise to distinct modes of action against Alzheimer’s disease.
Using an Alzheimer’s disease mouse model (APP/PS1) harboring human dementia-associated genes, the research team demonstrated that these compounds also exert distinct therapeutic effects in vivo.
Alzheimer’s disease does not arise from a single cause. Rather, multiple pathological factors, including amyloid-b, metal ions, and reactive oxygen species, interact synergistically to exacerbate disease progression. In particular, metal ions bind to amyloid-b, modulating its aggregation and toxicity while promoting the generation of reactive oxygen species, which in turn accelerates neuronal damage. Effective control of Alzheimer’s disease therefore requires therapeutic strategies capable of simultaneously targeting multiple interrelated pathological processes.
< Alzheimer’s Disease – Chemical Approach Illustration (AI-generated image) >
The researchers focused on positional isomers, molecules composed of the same chemical elements but differing only in the positions at which those elements are connected. Remarkably, simple changes in molecular positioning resulted in pronounced differences in reactivity towards reactive oxygen species, as well as in interactions with amyloid-b and metal-bound amyloid-b.
To investigate these effects, the team compared the reactivities of three structurally similar molecules differing only in the positions of their functional groups. Their analyses revealed that even minimal structural rearrangements led to significant differences in antioxidant capacity and produced distinct modes of modulation of amyloid-b and metal-bound amyloid-b through different mechanisms, inducing peptide chemical modifications.
In other words, the study demonstrated that Alzheimer’s disease-related pathological factors can be regulated through mechanistically distinct pathways simply by altering molecular arrangement, without changing molecular composition.
Notably, a specific positional isomer capable of simultaneously modulating reactive oxygen species, amyloid-b, and metal-bound amyloid-b complexes also demonstrated therapeutic efficacy in an Alzheimer’s disease mouse model. In these experiments, the compound reduced oxidative stress in the hippocampus, the brain region critical for memory, and decreased amyloid plaque accumulation, resulting in significant improvements in memory deficits and cognitive impairment.
< In Vivo Efficacy Evaluation and Biological Outcomes According to Positional Isomers of Small-Molecule Compounds >
Professor Mi Hee Lim of KAIST stated, “This study demonstrates that multiple pathological factors associated with Alzheimer’s disease can be targeted simultaneously simply by adjusting molecular positioning, without altering the molecule’s core chemical framework.” She added, “These findings point to a new therapeutic strategy that may enable more precise control of complex, multifactorial diseases such as Alzheimer’s disease.”
This research was conducted with Chanju Na and Jimin Lee, integrated master’s-doctoral students in the Department of Chemistry at KAIST, who served as co-first authors. The results were published in the Journal of the American Chemical Society (Impact Factor: 15.7, top 5.0% in Chemistry) in Issue 1 dated January 14, 2026.
※ Paper title: “Positional Isomerism Tunes Molecular Reactivities and Mechanisms toward Pathological Targets in Dementia”
※ DOI: 10.1021/jacs.5c14323
This study was supported by the National Research Foundation (NRF) of Korea through the Basic Research Program (Creative Research Initiative and Global Science Research Center), the NRF Sejong Science Fellowship, the NRF Ph.D. Followship, and KRIBB Institutional Funding.
2026.01.26 View 2030 -
KAIST Directly Visualizes the Hidden Spatial Order of Electrons in a Quantum Material
<(Back row, from left) Yeongkwan Kim, SungBin Lee, Heejun Yang, Yongsoo Yang_(Front row, from left) Jemin Park, Seokjo Hong, Jaewhan Oh>
· Cryogenic 4D-STEM reveals how charge density waves form, fragment, and persist across a phase transition
· First direct measurement of electronic amplitude correlations uncovers strain-driven inhomogeneity and localized order above the transition temperature
Electronic order in quantum materials often emerges not uniformly, but through subtle and complex patterns that vary from place to place. One prominent example is the charge density wave (CDW), an ordered state in which electrons arrange themselves into periodic patterns at low temperatures. Although CDWs have been studied for decades, how their strength and spatial coherence evolve across a phase transition has remained largely inaccessible experimentally.
Now, a team led by Professor Yongsoo Yang of the Department of Physics at KAIST (Korea Advanced Institute of Science and Technology), together with Professors SungBin Lee, Heejun Yang, and Yeongkwan Kim, and in collaboration with Stanford University, has for the first time directly visualized the spatial evolution of charge density wave amplitude order inside a quantum material.
A New Way to See Electronic Order at the Nanoscale
Using a liquid-helium-cooled electron microscope setup combined with four-dimensional scanning transmission electron microscopy (4D-STEM), the researchers mapped how CDW order develops, weakens, and fragments as temperature changes. This approach allowed them to reconstruct nanoscale maps of the CDW amplitude, revealing not just whether the order exists, but how strong it is and how it is spatially connected.
This study is similar to filming the growth of ice crystals as water freezes using an ultra-high-magnification camera. In this case, however, the researchers observed electrons arranging themselves at cryogenic temperatures of around –253°C, and used an electron microscope capable of resolving features one hundred-thousandth the width of a human hair instead of a conventional camera. The results showed that the electronic patterns do not appear uniformly across the material. In some regions, clear patterns are visible, while in neighboring areas they are entirely absent, much like a lake that does not freeze all at once, with patches of ice interspersed with liquid water.
How Electronic Order Breaks Apart in Real Space
The team further demonstrated that this spatial inhomogeneity is closely linked to local strain inside the crystal. Even extremely small distortions that are far below optical resolution strongly suppress the CDW amplitude. This clear anticorrelation between strain and electronic order provides direct evidence that local lattice distortions play a decisive role in shaping CDW patterns.
Unexpectedly, the researchers also observed that localized regions of CDW order can persist even above the transition temperature, where long-range order is generally thought to disappear. These isolated pockets of electronic order suggest that the CDW transition is not a simple, uniform melting process, but instead involves gradual loss of spatial coherence.
A key advance of this work is the world’s first direct measurement of CDW amplitude correlations. By quantifying how the strength of electronic order at one location is related to that at another, the study reveals how CDW coherence collapses across the transition, while local amplitude remains finite. Such information could not be obtained with conventional diffraction or scanning probe techniques.
Toward a New Framework for Studying Electronic Order
Charge density waves are a central feature of many quantum materials and often coexist or compete with other electronic states. By directly accessing their spatial structure and correlations, this study provides a new experimental framework for understanding how collective electronic order forms and evolves in real materials.
Dr. Yongsoo Yang, who led the research, explained the significance of the results: “Until now, the spatial coherence of charge density waves was largely inferred indirectly. Our approach allows us to directly visualize how electronic order varies across space and temperature, and to identify the factors that locally stabilize or suppress it.”
[Figure 1] Schematic illustration of an experiment employing 4D-STEM to probe the spatial variations of charge density waves in the prototypical quantum material NbSe2 under a liquid-helium cryogenic environment (AI-generated image).
This research, with Seokjo Hong, Jaewhan Oh and Jemin Park of KAIST as co-first authors, was published online in Physical Review Letters on January 6th (Title: Spatial correlations of charge density wave order across the transition in 2H-NbSe2).
The study was mainly supported by the National Research Foundation of Korea (NRF) Grants (Individual Basic Research Program, Basic Research Laboratory Program, Nanomaterial Technology Development Program) funded by the Korean Government (MSIT).
2026.01.20 View 2263 -
KAIST Proposes a Multinational AI Cooperation Strategy Beyond U.S.–China Dominance
2026.01.19 View 2664 -
Chairman Jae-Chul Kim of Dongwon Group Donates a Total of 60.3 Billion Won to KAIST
<Jae-Chul Kim, Honorary Chairman of Dongwon Group>
"In the era of AI, a new future lies within the sea of data. I ask that KAIST leaps forward to become the world's No. 1 AI research group." — Jae-Chul Kim, Honorary Chairman of Dongwon Group
KAIST announced on January 16th that Honorary Chairman Jae-Chul Kim of Dongwon Group has pledged an additional 5.9 billion KRW in development funds to foster Artificial Intelligence (AI) talent and strengthen research infrastructure, bringing his total contribution to 60.3 billion KRW. This marks his second additional donation since 2020, continuing his steadfast support for strengthening South Korea's national competitiveness in the field of AI.
Through his initial donation in 2020, Chairman Kim established the 'Kim Jaechul Graduate School of AI' at KAIST, urging the university to secure world-class capabilities. Upon hearing that KAIST’s AI research level ranked 5th among global universities over the past five years (2020–2024), Chairman Kim requested that the university strive to reach the No. 1 spot in the world.
In response, President Kwang Hyung Lee explained, "To surpass Carnegie Mellon University (CMU), which is currently evaluated as the world’s best with an AI faculty of about 45, the KAIST Graduate School of AI needs to expand its faculty to over 50 and construct a dedicated research building." Chairman Kim responded by saying, "I will build the building," and this latest donation is a fulfillment of that promise.
This third pledge of 5.9 billion KRW was decided to cover the projected budget shortfall as the design of the AI Education and Research Building enters full-scale development.
The AI Education and Research Building will be a facility with 8 floors above ground and 1 basement level, covering a total floor area of 18,182 m² (approx. 5,500 pyeong). It is scheduled for completion in February 2028. Once finished, it will serve as a global AI research hub housing 50 faculty members and 1,000 students.
Since the 2021 academic year, KAIST has been selecting 60 Master’s and 10 Doctoral students annually as 'Dongwon Scholars' outside of the regular quota for a period of 10 years. While the tuition and research incentives for the first three years were supported by the donation, KAIST has been utilizing its own budget since the 2024 academic year to ensure students can focus entirely on their research.
Moving forward, the Kim Jaechul Graduate School of AI plans to build a world-class faculty and operate systematic Master's and Doctoral programs to cultivate global AI leaders. In addition to technical expertise, the school will offer educational programs focused on character and holistic development, leading the charge in strengthening Korea's AI competitiveness.
Honorary Chairman Jae-Chul Kim stated, "I hope this donation serves as a small 'priming water' for South Korea to leap forward as an AI powerhouse. I look forward to seeing global core talents grow here and contribute to our national strength."
President Kwang Hyung Lee expressed his gratitude, saying, "Chairman Kim’s unwavering support is the greatest driving force for KAIST to secure global AI sovereignty. We will ensure the Kim Jaechul Graduate School of AI becomes a mecca where the world's best AI minds gather to innovate, honoring the Chairman’s vision."
2026.01.16 View 2787 -
Seeing Black Holes More Clearly with Laser Light
<(From Left) Researcher Junyong Choi, Researcher Woosong Jeong, Professor Jungwon Kim, Researcher Jihoon Baek >
Radio telescopes are instruments that capture faint radio signals from space and convert them into images of celestial bodies. To observe distant black holes clearly, multiple radio telescopes must capture cosmic signals at exactly the same time, acting as a single unit. Research teams at KAIST have developedr a new reference signal technology that uses laser light to precisely synchronize the observation timing and phase of these telescopes.
KAIST announced on January 15th that a research team led by Professor Jungwon Kim from the Department of Mechanical Engineering—in collaboration with the Korea Astronomy and Space Science Institute, the Korea Research Institute of Standards and Science, and the Max Planck Institute for Radio Astronomy (MPIfR) in Germany—has implemented a technology that directly applies optical frequency comb lasers to radio telescope receivers.
While a typical laser emits only one color (frequency), an optical frequency comb laser emits tens of thousands of extremely accurate colors arranged at regular intervals. This appearance resembles the teeth of a comb, hence the name "frequency comb." Since the frequency of each individual "tooth" is known exactly and the intervals can be precision-tuned to the level of an atomic clock, scientists refer to it as an "ultra-precision ruler made of light."
The core of Very Long Baseline Interferometry (VLBI), a technique where multiple radio telescopes observe simultaneously, is aligning the phases of the radio signals received by each telescope as if aligning them to a single precise ruler. However, existing electronic reference signal methods faced limitations; as observation frequencies increased, precise phase calibration is becoming more difficult.
In response, the KAIST research team developed a method to deliver the optical frequency comb laser directly into the radio telescope, based on the idea of "improving the fundamental precision of phase alignment by utilizing light (lasers) from the signal generation stage." Through this, they successfully solved the problems of reference signal generation and phase calibration simultaneously within a single optical system.
If the conventional method was like using a "ruler that makes phase alignment difficult" at higher frequencies, this new technology can be compared to setting a standard with an "ultra-precision ruler that fixes the phase with extremely stable light." As a result, they have laid the foundation for distant radio telescopes to interoperate as elaborately as one giant telescope.
This technology was verified through test observations at the Korea VLBI Network (KVN) Yonsei Radio Telescope. The research team succeeded in detecting stable interference patterns (fringes) between radio telescopes and proved through actual observation that precise phase calibration is possible. Recently, this system was also installed at the KVN SNU Pyeongchang Radio Telescope, leading to expanded experiments using multiple observation sites simultaneously.
The team expects that this will not only allow for clearer imaging of black holes but also drastically reduce phase delay errors between instruments—a long-standing issue in VLBI observations.
The applications of this technology are not limited to astronomical observations. The team anticipates that it can be expanded to various advanced fields requiring precise space-time measurements, such as▲ Intercontinental ultra-precision clock comparison ▲Space geodesy ▲Deep-space probe tracking
< Illustration of the system principle (Image generated by AI) >
Professor Jungwon Kim of KAIST stated, "This research is a case where the limits of existing electronic signal generation technology were overcome by directly applying optical frequency comb lasers to radio telescopes. It will significantly contribute to improving the precision of next-generation black hole observations and advancing the fields of frequency metrology and time standards."
Dr. Minji Hyun (currently at KRISS) and Dr. Changmin Ahn from KAIST participated as co-first authors. The research findings were published on January 4th in the international academic journal Light: Science & Applications.
Paper Title: Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration
DOI: 10.1038/s41377-025-02056-w
Lead Authors: Dr. Minji Hyun (KAIST, currently KRISS), Dr. Changmin Ahn (KAIST), Jungwon Kim (KAIST)
This research was conducted with support from the National Research Council of Science & Technology (NST) Creative Alliance Project(CAP), the National Research Foundation of Korea (NRF), and the Institute of Information & Communications Technology Planning & Evaluation (IITP).
2026.01.15 View 3194 -
Breaking the 1% Barrier, KAIST Boosts Brightness of Eco-Friendly Ultra-Small Semiconductors by 18-Fold
<(Front rwo, from left) KAIST co-first author Changhyun Joo, co-first author Seongbeom Yeon, (Back row, from left) Jaeyoung Ha, Professor Himchan Cho, Jaedong Jang>
Light-emitting semiconductors are used throughout everyday life in TVs, smartphones, and lighting. However, many technical barriers remain in developing environmentally friendly semiconductor materials. In particular, nanoscale semiconductors that are tens of thousands of times smaller than the width of a human hair (about 100,000 nanometers) are theoretically capable of emitting bright light, yet in practice have suffered from extremely weak emission. KAIST researchers have now developed a new surface-control technology that overcomes this limitation.
KAIST (President Kwang Hyung Lee) announced on the 14th of January that a research team led by Professor Himchan Cho of the Department of Materials Science and Engineering has developed a fundamental technology to control, at the atomic level, the surface of indium phosphide (InP)* magic-sized clusters (MSCs)—nanoscale semiconductor particles regarded as next-generation eco-friendly semiconductor materials.* Indium phosphide (InP): a compound semiconductor made of indium (In) and phosphorus (P), considered an environmentally friendly alternative that does not use hazardous elements such as cadmium
The material studied by the team is known as a magic-sized cluster, an ultrasmall semiconductor particle composed of only several tens of atoms. Because all particles have identical size and structure, these materials are theoretically capable of emitting extremely sharp and pure light. However, due to their extremely small size of just 1–2 nanometers, even minute surface defects cause most of the emitted light to be lost. As a result, luminescence efficiency has remained below 1% to date.
Previously, this issue was addressed by etching the surface with strong chemicals such as hydrofluoric acid (HF). However, the overly aggressive reactions often damaged the semiconductor itself.
Professor Cho’s team adopted a different approach. Instead of removing the surface all at once, they devised a precision etching strategy that allows chemical reactions to proceed in a highly controlled, incremental manner. This enabled selective removal of only the defect sites that hindered light emission, while preserving the overall structure of the semiconductor. During this defect-removal process, fluorine generated by the reaction combined with zinc species in the solution to form zinc chloride, which in turn stabilized and passivated the exposed nanocrystal surface.
< Schematic illustration of overcoming emission efficiency limits via atomic-scale precision control >
As a result, the research team increased the luminescence efficiency of the semiconductor from below 1% to 18.1%. This represents the highest reported performance to date among indium phosphide–based ultrasmall nanosemiconductors, corresponding to an 18-fold increase in brightness.
This study is particularly significant in that it demonstrates, for the first time, that the surfaces of ultrasmall semiconductors—previously considered nearly impossible to control—can be precisely engineered at the atomic level. The technology is expected to find applications not only in next-generation displays, but also in advanced fields such as quantum communication and infrared sensing.
< Eco-friendly Ultra-compact Semiconductor Chemical Reaction (AI-generated image) >
Professor Himchan Cho explained, “This work is not simply about making brighter semiconductors, but about demonstrating how critical atomic-level surface control is for achieving desired performance.”
This research was carried out with Changhyun Joo, a doctoral student, and Seongbeom Yeon, a combined master’s-doctoral student in the Department of Materials Science and Engineering at KAIST, serving as co–first authors. Professor Himchan Cho and Professor Ivan Infante of the Basque Center for Materials, Applications, and Nanostructures (BCMaterials, Spain) participated as co-corresponding authors. The study was published online on December 16 in the Journal of the American Chemical Society (JACS), one of the most prestigious journals in chemistry.
※ Paper title: “Overcoming the Luminescence Efficiency Limitations of InP Magic-Sized Clusters,” DOI: 10.1021/jacs.5c13963
This research was supported by the National Research Foundation of Korea through the Nano Materials Technology Development Program, the Next-Generation Intelligent Semiconductor Technology Development Program, the Quantum Information Science Human Infrastructure Program, and by the Korea Basic Science Institute through its Infrastructure Support Program for Early-Career Researchers.
2026.01.14 View 2417 -
KAIST–Daekyo, Opening of the Cognitive Enhancement Research Center Lounge
< Group photo of officials at the opening ceremony of the KAIST–Daekyo Cognitive Enhancement Research Center Lounge >
KAIST held the opening ceremony for the ‘KAIST–Daekyo Cognitive Enhancement Research Center Lounge,’ jointly established with Daekyo, at the Meta-Convergence Hall on the Daejeon main campus last Saturday, the 10th.
This lounge was established through an in-kind donation by Daekyo for space creation as part of research cooperation. It was designed as a base space to more systematically operate brain development and cognitive function enhancement research that KAIST and Daekyo have been jointly promoting, and to share research results with society. Through this event, KAIST introduced the achievements of its research cooperation to date and provided a forum to explore the future directions of education and brain science.
Key KAIST officials, including Kyun Min Lee, Vice President for Provost and Academic Affairs, and Dae-Soo Kim, Dean of the College of Life Science and Bioengineering, as well as officials from both organizations, including Ho-joon Kang, CEO of Daekyo, attended the event to celebrate the opening of the lounge.
Since signing a Memorandum of Understanding (MOU) for industry-academic research cooperation with Daekyo in 2023, our university has been jointly conducting research on cognitive function enhancement and mental health across the entire life cycle—from infants to adults and seniors—based on brain and cognitive science. The cooperation continues to expand these research results into educational content and solutions.
An official from Daekyo stated, "The Cognitive Enhancement Research Center Lounge is a symbolic space for the research cooperation accumulated by both organizations, and it is highly meaningful to be able to communicate directly with customers and share research results here. Moving forward, Daekyo will continue to expand its cooperation with KAIST to prove the value of scientific and systematic education."
Kyun Min Lee, Vice President for Provost and Academic Affairs, said, "The opening of this lounge is significant in that a space for industry-academic cooperation research was created through Daekyo’s donation. Based on this space, KAIST will strive to share the achievements of brain and cognitive science research with society and contribute to the field of education."
2026.01.12 View 1357 -
KAIST detects ‘hidden defects’ that degrade semiconductor performance with 1,000× higher sensitivity
<(From Left) Professor Byungha Shin, Ph.D candidate Chaeyoun Kim, Dr. Oki Gunawan>
Semiconductors are used in devices such as memory chips and solar cells, and within them may exist invisible defects that interfere with electrical flow. A joint research team has developed a new analysis method that can detect these “hidden defects” (electronic traps) with approximately 1,000 times higher sensitivity than existing techniques. The technology is expected to improve semiconductor performance and lifetime, while significantly reducing development time and costs by enabling precise identification of defect sources.
KAIST (President Kwang Hyung Lee) announced on January 8th that a joint research team led by Professor Byungha Shin of the Department of Materials Science and Engineering at KAIST and Dr. Oki Gunawan of the IBM T. J. Watson Research Center has developed a new measurement technique that can simultaneously analyze defects that hinder electrical transport (electronic traps) and charge carrier transport properties inside semiconductors.
Within semiconductors, electronic traps can exist that capture electrons and hinder their movement. When electrons are trapped, electrical current cannot flow smoothly, leading to leakage currents and degraded device performance. Therefore, accurately evaluating semiconductor performance requires determining how many electronic traps are present and how strongly they capture electrons.
The research team focused on Hall measurements, a technique that has long been used in semiconductor analysis. Hall measurements analyze electron motion using electric and magnetic fields. By adding controlled light illumination and temperature variation to this method, the team succeeded in extracting information that was difficult to obtain using conventional approaches.
Under weak illumination, newly generated electrons are first captured by electronic traps. As the light intensity is gradually increased, the traps become filled, and subsequently generated electrons begin to move freely. By analyzing this transition process, the researchers were able to precisely calculate the density and characteristics of electronic traps.
The greatest advantage of this method is that multiple types of information can be obtained simultaneously from a single measurement. It allows not only the evaluation of how fast electrons move, how long they survive, and how far they travel, but also the properties of traps that interfere with electron transport.
The team first validated the accuracy of the technique using silicon semiconductors and then applied it to perovskites, which are attracting attention as next-generation solar cell materials. As a result, they successfully detected extremely small quantities of electronic traps that were difficult to identify using existing methods—demonstrating a sensitivity approximately 1,000 times higher than that of conventional techniques.
< Conceptual Diagram of the Evolution of Hall Characterization (Analysis) Techniques >
Professor Byungha Shin stated, “This study presents a new method that enables simultaneous analysis of electrical transport and the factors that hinder it within semiconductors using a single measurement,” adding that “it will serve as an important tool for improving the performance and reliability of various semiconductor devices, including memory semiconductors and solar cells.”
The results of this research were published on January 1 in Science Advances, an international academic journal, with Chaeyoun Kim, a doctoral student in the Department of Materials Science and Engineering, as the first author.
※ Paper title: “Electronic trap detection with carrier-resolved photo-Hall effect,” DOI: https://doi.org/10.1126/sciadv.adz0460
This research was supported by the Ministry of Science and ICT and the National Research Foundation of Korea.
< Conceptual Diagram of Charge Transport and Trap Characterization Using Photo-Hall Measurements (AI-generated image) >
2026.01.08 View 2738 -
KAIST Solves Key Commercialization Challenges of Next-Generation Anode-Free Lithium Batteries
<(From Left) Ph.D candidate Juhyun Lee, Postdoctoral Researcher Jinuk Kim, (Upper Right) Professor Jinwoo Lee>
Anode-free lithium metal batteries, which have attracted attention as candidates for electric vehicles, drones, and next-generation high-performance batteries, offer much higher energy density than conventional lithium-ion batteries. However, their short lifespan has made commercialization difficult. KAIST researchers have now moved beyond conventional approaches that required repeatedly changing electrolytes and have succeeded in dramatically extending battery life through electrode surface design alone.
KAIST (President Kwang Hyung Lee) announced on the 4th of January that a research team led by Professors Jinwoo Lee and Sung Gap Im of the Department of Chemical and Biomolecular Engineering fundamentally resolved the issue of interfacial instability—the greatest weakness of anode-free lithium metal batteries—by introducing an ultrathin artificial polymer layer with a thickness of 15 nanometers (nm) on the electrode surface.
Anode-free lithium metal batteries have a simple structure that uses only a copper current collector instead of graphite or lithium metal at the anode. This design offers advantages such as 30–50% higher energy density compared to conventional lithium-ion batteries, lower manufacturing costs, and simplified processes. However, during the initial charging process, lithium deposits directly onto the copper surface, rapidly consuming the electrolyte and forming an unstable solid electrolyte interphase (SEI), which leads to a sharp reduction in battery lifespan.
Rather than changing the electrolyte composition, the research team chose a strategy of redesigning the electrode surface where the problem originates. By forming a uniform ultrathin polymer layer on the copper current collector using an iCVD (initiated chemical vapor deposition) process, they found that this layer regulates interactions with the electrolyte, precisely controlling lithium-ion transport and electrolyte decomposition pathways.
<Figure 1. Schematic of an ultrathin artificial polymer layer (15 nm thick) introduced onto the electrode surface>
In conventional batteries, electrolyte solvents decompose to form soft and unstable organic SEI layers, causing non-uniform lithium deposition and promoting the growth of sharp, needle-like dendrites. In contrast, the polymer layer developed in this study does not readily mix with the electrolyte solvent, inducing the decomposition of salt components rather than solvents. As a result, a rigid and stable inorganic SEI is formed, simultaneously suppressing electrolyte consumption and excessive SEI growth.
Using operando Raman spectroscopy and molecular dynamics (MD) simulations, the researchers identified the mechanism by which an anion-rich environment forms at the electrode surface during battery operation, leading to the formation of a stable inorganic SEI.
This technology requires only the addition of a thin surface layer without altering electrolyte composition, offering high compatibility with existing manufacturing processes and minimal cost burden. In particular, the iCVD process enables large-area, continuous roll-to-roll production, making it suitable for industrial-scale mass production beyond the laboratory.
<Figure 2. Design rationale of the current collector-modifying artificial polymer layer and the SEI formation mechanism>
Professor Jinwoo Lee stated, “Beyond developing new materials, this study is significant in that it presents a design principle showing how electrolyte reactions and interfacial stability can be controlled through electrode surface engineering,” adding, “This technology can accelerate the commercialization of anode-free lithium metal batteries in next-generation high-energy battery markets such as electric vehicles and energy storage systems (ESS).”
This research was conducted with Ph.D candidate Juhyun Lee, and postdoctoral Jinuk Kim, a postdoctoral researcher from the Department of Chemical and Biomolecular Engineering at KAIST, serving as co–first authors. The results were published on December 10, 2025, in Joule, one of the most prestigious journals in the field of energy.
※ Paper title: “A Strategic Tuning of Interfacial Li⁺ Solvation with Ultrathin Polymer Layers for Anode-Free Lithium Metal Batteries,” Authors: Juhyun Lee (KAIST, co–first author), Jinuk Kim (KAIST, co–first author), Jinwoo Lee (KAIST, corresponding author), Sung Gap Im (KAIST, corresponding author), among a total of 18 authors, DOI: 10.1016/j.joule.2025.102226
This research was conducted at the Frontier Research Laboratory, jointly established by KAIST and LG Energy Solution, and was supported by the National Research Foundation of Korea (NRF) Mid-Career Research Program, the Korea Forest Service (Korea Forestry Promotion Institute) Advanced Technology Development Program for High Value-Added Wood Resources, and the KAIST Jang Young Sil Fellowship Program.
2026.01.05 View 2723