Department of Energy System

Department of Energy Systems

Department of Energy Systems Research

Leading super-convergence renewable energy research and education to achieve carbon-neutrality.

Department of Energy Systems

Department of Energy Systems Research

Leading super-convergence renewable energy research and education to achieve carbon-neutrality.

4th BK21 Project News

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#AS-ALD # Intelligent Semiconductor Engineering #Department of Electrical and Computer Engineering

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Prof. Ilkwon Oh’s Research Team Develops AS-ALD Technology for Semiconductor Miniaturization

- Area-Selective Atomic Layer Deposition (AS-ALD) Gains Attention as a Key Breakthrough Technology - Enables Patterning Without Exclusive 'EUV Equipment', Allowing for Customized Fabrication * Caption for the image above: An illustration showing the selective formation of red-colored aluminum oxide (Al₂O₃) only at the grain boundaries — the leakage current pathways — of zirconium dioxide (ZrO₂) through the new area-selective atomic layer deposition (AS-ALD) process developed by the Ajou University joint research team. This technology is expected to maximize storage capacity while minimizing data loss in DRAM devices. Professor Ilkwon Oh’s research team at Ajou University has developed a technology that enhances the precision of semiconductor processes through area-selective atomic layer deposition (AS-ALD). This advancement is expected to play a crucial role in the manufacturing of next-generation miniaturized and high-density semiconductor devices. Professor Ilkwon Oh (Department of Intelligent Semiconductor Engineering and Department of Electrical and Computer Engineering) and a joint research team from the Samsung Advanced Institute of Technology (SAIT) announced their successful development of an AS-ALD technology that can significantly improve the precision of thin film deposition in semiconductor fabrication. Their research was published in the April issue of Advanced Science under the title “Area-Selective Atomic Layer Deposition on Homogeneous Substrate for Next-Generation Electronic Devices.” Minjeong Lee, Byungjun Won, and Youngjin Lim (Master’s students from the Department of Intelligent Semiconductor Engineering at Ajou University) participated as co-first authors, and Professor Ilkwon Oh served as the corresponding author. Dr. Seonghyun Kim and Dr. Jungkyu Song from SAIT also contributed as co-authors. Area-Selective Atomic Layer Deposition (AS-ALD) is a process that enables deposition to occur only on specific areas of a semiconductor substrate. This technology allows precise application of desired materials to selected locations on the semiconductor surface. Traditional Atomic Layer Deposition (ALD), widely used in semiconductor processes, forms uniform thin films across the entire substrate. It has been a key technique in the manufacturing of memory devices such as DRAM and NAND flash, as well as non-memory (system) semiconductors. However, as semiconductor devices continue to shrink and become more densely integrated, there is an increasing demand for selective thin-film deposition to reduce process steps, lower manufacturing costs, minimize error rates, and improve precision and efficiency. Consequently, AS-ALD has emerged as a core next-generation semiconductor processing technology, attracting attention as a breakthrough solution capable of overcoming the technical limits currently facing the semiconductor industry. By employing AS-ALD, many conventional process steps can be eliminated, dramatically lowering manufacturing costs and the potential for errors. Additionally, AS-ALD enables semiconductor patterning without the need for expensive extreme ultraviolet (EUV) lithography equipment, which has been monopolized by certain companies, further intensifying industrial and academic interest. Furthermore, AS-ALD opens possibilities for customized fabrication of new types of three-dimensional micro-semiconductor devices that are difficult to achieve using traditional techniques and equipment. Despite these advantages, the implementation of AS-ALD in actual semiconductor mass production has faced significant challenges. Depending on the chemical materials and substrates used, maintaining precise selective deposition has been difficult, and electrical performance degradation has often been observed when applied to real devices. To overcome these limitations, the Ajou University research team targeted the widely used ZAZ (ZrO₂/Al₂O₃/ZrO₂) capacitor layer structure in DRAM processes. Specifically, they selectively deposited aluminum oxide (Al₂O₃) only at the grain boundaries—the paths where leakage currents typically occur—thereby minimizing unnecessary Al₂O₃ deposition and effectively improving device performance and reliability. * Transmission electron microscope (TEM) images and chemical composition analysis confirmed the selective formation of Al₂O₃ at grain boundaries. Graphs b and c illustrate the concentration of Al depending on the distance from the grain boundaries, verifying the selective deposition of Al₂O₃ at the desired locations. Using zirconium dioxide (ZrO₂) substrates, the research team experimentally analyzed and demonstrated the mechanisms for selective deposition, proving that selective control was feasible. They also confirmed that AS-ALD not only enhances semiconductor device performance but also significantly reduces unwanted leakage currents. This breakthrough suggests a method to maximize storage efficiency in DRAM devices and minimize data loss during device miniaturization, marking an important technical milestone for memory device advancement. Professor Ilkwon Oh stated, "While area-selective atomic layer deposition is essential for overcoming technological barriers in the semiconductor industry, there have been many challenges in applying it to real processes. Our research experimentally demonstrates that selective deposition and control are achievable, representing a significant advance in semiconductor processing technology." He added, "We will continue further research to enhance device performance and improve process efficiency for industrial applications." The Ajou University research team plans to pursue follow-up studies to develop more precise control techniques for atomic layer deposition processes and to explore their industrial applicability.

#Eco-Friendly #Lifespan #conventional supercapacitor system #National Research Foundation

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Prof. Taekwang Yoon’s Research Team Develops Eco-Friendly Additive to Enhance Performance and Lifespan of Supercapacitor

* In the photo above – from left: Professor Taekwang Yoon (Ajou University), Seonghun Lee (Ph.D. integrated program student, Ajou University), Ji-Young Park (Master’s student, Ajou University), and Hyungseob Yoon (Ph.D. integrated program student, Chung-Ang University). Professor Taekwang Yoon’s research team at Ajou University has developed a natural rubber-based electrolyte additive that dramatically improves the performance and lifespan of supercapacitors. By utilizing eco-friendly and cost-effective materials, this innovation is expected to become a significant milestone in securing the sustainability of supercapacitors, one of the leading high-performance energy storage technologies. Professor Taekwang Yoon (Department of Applied Chemistry and Graduate School of Molecular Science and Technology) and his team announced that they successfully enhanced the performance and durability of supercapacitors by developing a novel electrolyte additive based on biopolymers. Their research findings were published online in the April issue of Energy Storage Materials under the title, “Long-lasting supercapacitor with stable electrode-electrolyte interface enabled by a biopolymer conjugate electrolyte additive.” Professor Yoon served as the corresponding author, with Seonghun Lee (Ph.D. integrated program student at Ajou University), Ji-Young Park (Master’s student at Ajou University), and Hyungseob Yoon (Ph.D. integrated program student at Chung-Ang University) contributing as co-first authors. Supercapacitors are next-generation energy storage devices that offer significant advantages over conventional batteries. They do not use lithium (Li), making them environmentally friendly, and are capable of storing large amounts of electrical energy. With their ability for rapid charge and discharge cycles and their virtually unlimited lifespan, supercapacitors are increasingly seen as a viable alternative to traditional batteries. They are already being utilized as supplementary power sources in fields such as electric vehicles and renewable energy systems, and are expected to find even broader applications in the future. Unlike batteries, which rely on chemical reactions and ion diffusion to store energy, supercapacitors store energy through surface-controlled reactions at the electrode-electrolyte interface. Thus, the stability of this interface plays a critical role in determining the electrochemical performance of supercapacitors. Because of this, ensuring the stability of the electrode-electrolyte interface has been a key research focus for improving supercapacitor performance. Various approaches have been explored, such as ▲polymer coatings ▲the use of self-healing inks based on 3D printing ▲surface modification using atomic layer deposition (ALD) techniques. However, these methods have faced limitations regarding process complexity, environmental concerns, high costs, and scalability challenges for mass production. In particular, maintaining stable interface characteristics over long periods while preserving high power output remains a major challenge. Over time, the electrode-electrolyte interface tends to become unstable, leading to the accumulation of by-products and the deterioration of electrochemical performance. In response, the Ajou University research team set a goal to develop a high-performance system that meets the demands of long-term stability, reliable operation, and environmental sustainability. a. Schematic of the supercapacitor developed by Professor Taekwang Yoon’s team at Ajou University. b. Schematic illustration of the electrode structure. c. Schematic depiction of the electrolyte additive fabrication process. The additive, made from gum kondagogu (a by-product of natural rubber production) and sodium alginate(extracted from seaweed), is eco-friendly, cost-effective, and highly efficient. To solve the instability problem of the electrode-electrolyte interface in conventional supercapacitor systems, the Ajou University research team developed a conjugated KS (gum kondagogu/sodium alginate) additive using eco-friendly natural rubber-derived gum kondagogu and sodium alginate extracted from seaweed. This additive boasts excellent solubility in aqueous electrolytes, improving ion conductivity and mobility, resulting in significantly enhanced performance compared to traditional electrolytes. Notably, adding even a small amount of the KS additive to sulfuric acid (H₂SO₄)-based electrolytes substantially improved interface characteristics. After 30,000 charge-discharge cycles, the capacitance retention rate increased from 58% to 93%. This remarkable result was achieved because the protective layer formed on the electrode surface suppressed by-product generation and facilitated smooth ion and electron transport. Compared to conventional chemically synthesized electrolytes, the KS additive-based electrolyte offers simpler processing and lower costs, making it highly promising for industrial applications. Additionally, the KS additive, being a natural polysaccharide-based biopolymer, is abundant, recyclable, and inexpensive, providing excellent scalability for mass production and large-scale processing. The research team expects that this study will establish a core technology for next-generation eco-friendly energy storage devices. In particular, electrodes made from the same biopolymers as the additive exhibit excellent flexibility and are easily manufacturable on a large scale, making them applicable not only to wearable electronics but also to large-scale energy storage systems. Professor Taekwang Yoon stated, "Through this research, we have significantly improved the electrode-electrolyte interface stability of supercapacitors, developing an eco-friendly and industrially applicable energy storage technology," and added, "We plan to continue with follow-up research aimed at applications in various fields." This research was supported by the Ministry of Science and ICT, the National Research Foundation of Korea, the University of Glasgow Startup Fund, and the AMRITA Seed Grant. *An image showing the flexibility of the large-area KS/CNT electrode developed by the Ajou University research team. The electrode maintains its structural integrity without damage under various mechanical deformations, suggesting its potential application in energy storage systems for wearable electronic devices.

#Ajou University #international student #Minister of Education

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Meeting with the Minister of Education and International Students_Strengthening Universities' Global Competence