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- [Research] Research team led by Prof. Joohoon Kang develops ternary logic transistor applying Heterojunction
- Research team led by Prof. Joohoon Kang develops ternary logic transistor applying Heterojunction - Next-generation semiconductor system technology that overcomes physical limitations of the traditional binary system [Image 1] Prof. Joohoon Kang Professor Joohoon Kang from AMSE and Prof. Jeong Ho Cho from Yonsei University developed the next-generation semiconductor system technology that enabled ternary logic. Research and development of high-performing semiconductors that rapidly process mass information is increasingly drawing attention owing to the growing demand for AI, autonomous driving, and IoT devices, which are at the center of the ongoing fourth industrial revolution. The binary logic system is currently facing mechanical limitations to improve integration per unit area; thereby, research on fabricating the multi-valued logic system has emerged as an alternative to achieve goals in order to enhance performance in processing information and power consumption. To address such challenges, the research team arranged stable "0", "1", and "2" states for ternary information processing by sequentially driving two types of semiconductors with different threshold voltages. Also, they demonstrated the flawless operation of various logical operations using the ternary system. Professor Kang stated, "I expect the technology to come into use in the semiconductor industry soon considering the system's excellent applicability in large-area at waferscale without major changes in the conventional semiconductor fabrication process." [Figure 2] Schematic and Working principle of multi-valued logic device With the result, researchers are embarking on discovering the ideal combination of semiconductor materials and are following up on a multi-valued logic study that surpasses the ternary logic. D.U.L. and S.B.J. contributed equally to this work. This work was supported by the National Research Foundation of Korea (NRF) grant, funded by the Korean Government (MSIT) (2020R1A4A2002806 and 2020R1C1C1009381) and the Creative Materials Discovery Program (2019M3D1A1078299) through the NRF of Korea funded by the Ministry of Science and ICT, Korea. This research was partially supported by the Yonsei University Research Fund of 2021. ※ Paper title : Multi-State Heterojunction Transistors Based on Field-Effect Tunneling-Transport Transitions ※ Source : https://onlinelibrary.wiley.com/doi/10.1002/adma.202101243 https://www.skku.edu/skku/campus/skk_comm/news.do?mode=view&articleNo=91055&article.offset=0&articleLimit=10
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- 작성일 2022-01-26
- 조회수 1394
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- [Research] Prof. Cho, Hyung Koun’s research team suggests Memory-Type NO2 sensing system using anisotropic Semiconductor materials
- Prof. Cho, Hyung Koun’s research team suggests Memory-Type NO2 sensing system using anisotropic Semiconductor materials [Figure 1] Prof. Cho, Ph.D candidate Young Been Kim (co-first author) and Sung Hyeon Jung Prof. Hyung Koun Cho’s research team (co-first author Ph.D candidate Young Been Kim and Sung Hyeon Jung) from the Department of Advanced Materials Science and Engineering developed a progressive memory-type gas sensing system that has not only an alert system for highly concentrated NO2, but also memory-type responses to detect the cumulative occurrence of irregular exposures of low gas concentrations, thereby leading to a wide range of detection in a single sensing device. Conventional toxic gas sensors’ primary function is to detect instantaneous gas emissions above fatal amounts. However, it is prevalent to be exposed to hazardous gas flow at concentrations lower than the lethal amount in practice, which is highly dangerous due to the cumulative effect. In order to produce signal according to irregular gas exposure, response and recovery processes should be occurring in the same environment whereas materials like typical n-type metal oxide semiconductors has difficulty acting so as it is operated through strong chemisorption. [Figure 2] Thus, the research team developed a novel system that enables both rapid alarm function at high concentration and memory-type gas sensing at low concentration based on designed antimony triselenide (Sb2Se3) nanoflakes. [Figure 3] Therefore, the research team developed a novel system that enables both rapid alarm function at high concentration and memory-type gas sensing at low concentration. Generally, low-dimensional material-based gas sensing can be operated at room temperature by Physisorption in the surface of van der Waals planes which means without any defect. On the other hand, the broken bonds of oxide-based sensing materials, i.e., dangling bonds, are driven by Chemisorption that reacts at high temperatures. Due to its anisotropic two-dimensional crystalline structure, the Sb2Se3 nanoflake structure exhibits anisotropy in which the formed surface consists of van der Waals crystal planes and dangling bond planes, enabling NO2 detection at both room temperature and high temperature. In particular, unlike existing materials, this Sb2Se3 gas sensor requires a very low-voltage (1V) at room temperature. It can be operated continuously without any processing due to its recovery characteristic based on designed antimony triselenide (Sb2Se3) nanoflakes. [Figure 4] According to the crystalline planes of conductive materials with Sb2Se3 nanoflake structure, the research team utilized physisorption and chemisorption devices to create a memory-type sensing system equipped with room temperature operation and recovery functions. [Figure 5] Prof. Cho stated, "I find the development of Sb2Se3 gas sensors very meaningful as it enabled real-time tracking of irregular and continuous toxic gas emission that can lead to a fatal situation when accumulated." This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. 2019R1A6A1A03033215). This work was also supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2021R1A2C3011870). https://www.skku.edu/skku/campus/skk_comm/news.do?mode=view&articleNo=90719&article.offset=0&articleLimit=10&srSearchVal=%EC%A1%B0%ED%98%95%EA%B7%A0
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- 작성일 2022-01-26
- 조회수 1383
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- [Research] AMSE Research team led by Prof. Sang-Woo Kim develops air-transmitted pathogen disinfection system applying triboelectri
- AMSE Research team led by Prof. Sang-Woo Kim develops air-transmitted pathogen disinfection system applying triboelectricity - Research team developed self-powered microbial disinfection using nanowire-enhanced localized electric field - Rapid disinfection of 0.025 seconds without needing extra electricity became possible - The system is expected to be applied to future ventilation system and hazmat suits [Image 1] Prof. Sang-woo Kim, Ph.D. Candidate Young Jun Kim Professor Sang-woo Kim’s research team from department of Advanced Materials Science & Engineering (AMSE) developed self-powered air-transmitted pathogen disinfection system based on triboelectric nanogenerator and nanowire. The research team achieved rapid inactivation of indoor/outdoor pathogens using triboelectricity generated by ambient energy such as mechanical vibration. Air-transmitted pathogens like SARS, MERS, and swine flu have caused serious damages on our community and economy as a whole. COVID-19, which is currently ongoing global pandemics, is also bringing about numerous infections and deaths. Given the time required to develop the vaccine, society should take proactive action to deter the spread of the epidemic. However, traditional high-efficiency particulate air (HEPA) filtration not only has drawbacks such as pressure drop and low throughput, but also cannot inactivate pathogens as it simply captures particles physically. Precipitator as well has risks as it generates ozone and requires kV-level high voltages. The research team found clue in the nanowire and triboelectricity. By forming an electric field out of triboelectricity and maximizing it through nanowires, research team demonstrated that airborne pathogens can easily be inactivated through electroporation method. The research team exposed E. coli (bacteria), B. subtilis (bacteria), and MS2 (virus) to the system and demonstrated that airborne pathogens, ranging from nanometer-level viruses to micrometer-level bacteria, can be easily removed through triboelectricity. Furthermore, the research team confirmed superior performance of the disinfection system of more than 99.99% inactivation of MS2 virus which has nanometer-level size at a fast air flow rate of 2 m/s. The system inactivates pathogens in mere 0.025 s without needing extra electricity. Also, pressure drop (24 Pa) of more than 50 times lower than widely-used H13 air filter is one of its promising feature. “Self-powered pathogen inactivation technology using static electricity overcomes the limitation of physical capture of the conventional filter.” Prof. Sang-woo Kim stated, adding “It can be applied in indoor and outdoor air ventilation technology that maximizes the energy efficiency of the circulation system due to low pressure drop albeit high pathogen disinfection efficiency of the system. We also expect this to be applied to masks and hazardous materials suits through follow-up research.” This work was supported by Nano Material Technology Development Program (2020M3H4A1A03084600) through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT and the GRRC program of Gyeonggi province (GRRC Sungkyunkwan 2017-B05). Z.-Y.H. acknowledges the support from the Korea Research Fellowship Program through the National Research Foundation of Korea (No. 2019H1D3A1A01102903). Z.-Y.H. also thanks the technical support from Dr. Rong Cheng from Renmin University of China and Dr. Jinling Xue from Helmholtz Zentrum München. This paper was published online in ‘Nature communications’ on June 17th. ※ Paper: Triboelectrification induced self-powered microbial disinfection using nanowire- enhanced localized electric field ※ Author contributions: Prof. Sang-Woo Kim (corresponding author, AMSE, SKKU), Ph.D. Candidate Young-Jun Kim (First author, Ph.D., SKKU), Dr. Zheng-Yang Huo (First author, research professor, SKKU), Researcher In-Yong Suh (Master’s program at SKKU), Researcher Dong-Min Lee (Ph.D. program at SKKU), Dr. Jeong Hwan Lee (Postdoctoral researcher at SKKU), Dr. Ye Du (Sichuan University), Researcher Si Wang (UESTC), Dr. Hong-Joon Yoon (Postdoctoral researcher at SKKU) https://www.skku.edu/skku/campus/skk_comm/news.do?mode=view&articleNo=90425&article.offset=20&articleLimit=10
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- 작성일 2022-01-26
- 조회수 1401
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- [Research] Prof. Sunkook Kim develops on-skin wearable multichannel electromyography sensor
- Prof. Sunkook Kim develops on-skin wearable multichannel electromyography sensor - Published online in IEEE Transaction on Industrial Electronics on May 10th, 2021 [Image 1] Prof. Sunkook Kim and Dr. Srinivas Gandla Prof. Sunkook Kim’s research team (Dr. Srinivas Gandla, First author) developed on-skin wearable multi-channel electromyography (EMG) sensor that enables controlling the robotic arm as smooth as human arm, even in long distance. Traditional PDMS was inconvenient for a long time usage due to the limited applicability and limitation in monitoring accurate EMG sensor values. Hence, the research team fabricated on-skin wearable multi-channel EMG sensor which can track human arm’s subtle EMG signal and built a system in which robot arms can move according to human gestures. The research team developed a high-sensitivity biosignal monitoring sensor featuring deformable EMG electrode design by applying Kirigami serpentine structures inspired by nature. To capture the wearer’s arm muscle movement in a stable manner, the sensor is equipped with a stretchable electrode structure exhibiting mechanical/electrical stability standing up to 150% of stress on x, y, and z-axis. ※ Kirigami : 'Kiri in Japanese means to cut, and 'gami', which means paper, when combined, refers to the form representing a stereoscopic shape when cut into a particular pattern or folded. Fig. 1. Large-area patched-based stretchable multichannel array sensor processed by laser ablation technique for robotic control. As control signal for digital devices by receiving human "gestures" through biosignals or EMG, this technology can be used in the contact-free industry, robot industry, and medical industry to connect people and digital devices. Dr. Gandla participated in this research with the support of Sungkyunkwan University's foreign researcher support initiative (해외우수신진연구자 사업). The findings, the stretchable electrode material technology, was applied to T&L’s (티앤엘(사)) Smart Thermometer in 2021. Fig. 2. Overview of the proposed multichannel sensor arrays for the robotic arm control system. “I hope the technology to be applied in an artificial EMG sensor system which can directly transmit user’s biosignals." Dr. Gandla stated. This work was supported by the National Research Foundation of Korea (2021R1A2B5B0200216 and 2018R1D1A1B0704 8232) and the SKKU Research Fellowship Program of Sungkyunkwan University. The paper was published online in one of the world-renowned journal, IEEE Transaction on Industrial Electronics, on May 10th, 2021 (Top 5% in electronics). https://www.skku.edu/skku/campus/skk_comm/news.do?mode=view&articleNo=89855&article.offset=0&articleLimit=10&srSearchVal=%EA%B9%80%EC%84%A0%EA%B5%AD
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- 작성일 2022-01-26
- 조회수 1400
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- [Research] Prof. Jeong Min Baik suggests a new approach for commercialization of sustainable energy harvesting
- Prof. Jeong Min Baik suggests a new approach for commercialization of sustainable energy harvesting technology - Development of non-contact mode triboelectric nanogenerator (TENG) applying C60-functionalized Polyimide - BiSbTe-based thermoelectric generators exhibit world's highest output through the triboelectrification field effect Contact electrification (CE), which occurs due to the coupling effect of two separate materials, is the foundation of triboelectric nanogenerators (TENG) that converts the ambient mechanical energy into electricity. TENGs have successfully demonstrated their excellence in charging small electronic devices and capturing momentary stimuli in devices like electronic skin, touch screens, healthcare devices, and habit-recognition security systems. Nevertheless, several drawbacks of contact electrification (CE) have been raised, such as the wear of materials, the need to replace the device, and noise resulting from its operation. In this regard, Prof. Baik’s research team, by fabricating C60-functionalized Polyimide, developed a non-contact mode nanogenerator, which shows 4.3 times higher output power and three times higher charge-retention characteristics. Non- contact mode TENG was applied in a keyless electronic door lock system and an automobile speed sensor for the first time in the world, demonstrating its stability and superiority in operation. Also, by pioneering the use of CE in thermoelectric harvesting, the research team suggested a novel approach by developing a brand new technology that profoundly enhanced output power without raising the necessity of thermoelectric material modification. Thermoelectric energy harvesting generated valuable energy utilizing the temperature difference on the material’s outside when heat is applied on both ends of the material. So far, the focus was on the modification of thermoelectric materials’ (Bi2Te3, SnSe, PbTe, etc.) Seebeck coefficient, electrical conductivity, and thermal conductivity to improve energy conversion efficiency; however, there were difficulties in commercialization due to low output voltage. To solve such problems, the research team attached a Kapton layer with a negative charge on the cold side of BiSbTe-based thermoelectric materials, which has the highest ZT value. It doubled output power and enabled setting a world record of 50% higher output voltage. “This research set the tone by attesting stable energy production capability by leveraging CE; The findings illuminated the unlimited potential in the field of energy harvesting.” Prof. Baik noted. The corresponding research was published in Energy & Environmental Science (IF 30.287) and ACS Energy Letters (IF: 19.003), respectively. https://www.skku.edu/skku/research/industry/researchStory_view.do?mode=view&articleNo=89863
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- 작성일 2022-01-26
- 조회수 1378
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- [Research] Prof. Hyoungsub Kim’ s research team in collaboration with Samsung Advanced Institute of Technology (SAIT) revealed dime
- Prof. Hyoungsub Kim’ s research team in collaboration with Samsung Advanced Institute of Technology (SAIT) revealed dimension-breaking reconstruction process during conversion of MoO2 to MoS2 [Figure 1] Professor Hyoungsub Kim (AMSE, co-corresponding author), Dr. Eunha Lee (SAIT, co-corresponding author) The joint research team led by Prof. Hyoungsub Kim (AMSE) and Dr. Eunha Lee (SAIT) first discovered the appearance of highly ordered arrays of 1D intermediate crystals during the chemical transformation of MoO2 to 2D layer-structured MoS2. Recently, for application to next-generation semiconductor and energy devices, numerous researches have been actively conducted to synthesize various 2D layer-structured materials (transition-metal dichalcogenides) via a thermal sulfidation- or selenization-based conversion process of metal oxides. Ideally, such a synthesis process follows sequential layer-by-layer phase transformation characteristics of an atomic layer-level thickness. During the sulfidation process of MoO2, the joint research team directly observed the appearance of highly ordered arrays of 1D intermediate crystals at the MoO2/MoS2 interface using STEM with an atomic-scale resolution. They also developed a comprehensive structural model and energetics of the intermediate crystals during the dimension-breaking transformation process (3D→1D→2D) based on the first-principles DFT calculations. [Figure 2] (left) Schematic illustration of chemical phase transformation, (right) STEM images Furthermore, by collaborating with a Prof. Mann-Ho Cho’s team (department of physics at Yonsei University), they proved possible modulation of the metal-contact type (from p- to n-type) with the number of atomic MoS2 layers via X-ray photoelectron spectroscopy, which can be used for innovative device applications. In this paper, Dr. Hyangsook Lee (SAIT) and Dr. Yeonchoo Cho (SAIT) contributed as co-first authors, and the results were published online in ‘Materials Today (Impact Factor = 26.416, JCR Ranking Top 2.7%)' on March 17, 2021. ※ Paper title: “3D-to-2D phase transformation through highly ordered 1D crystals from transition-metal oxides to dichalcogenides” ※ Paper source: https://www.sciencedirect.com/science/article/abs/pii/S1369702121000560 https://www.skku.edu/skku/campus/skk_comm/news.do?mode=view&articleNo=89231&article.offset=20&articleLimit=10
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- 작성일 2022-01-26
- 조회수 1414
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- [Research] Prof. Jeong Min Baik’s Research Team Suggest a New Paradigm of Study on Thermoelectric Energy-harvesting
- Prof. Jeong Min Baik’s Research Team Suggest a New Paradigm of Study on Thermoelectric Energy-harvesting - highest output voltage of BisbTe-based thermoelectric generator - published in ACS Energy Letters on February 2021 [Image] Prof. Jeong Min Baik (School of Advanced Materials Science and Engineering, SKKU) and Prof. Jae Sung Son (School of Materials Science and Engineering, UNIST) Prof. Baik’s research team and Prof. Son’s research team developed a new technique to increase the output voltage of a thermoelectric generator that does not involve material modification. Thermoelectric energy-harvesting is a technology that produces useful energy by utilizing temperature differences at both ends of the material when heat is applied from the outside. It has attracted a great deal of research interest due to its simplicity, minimal maintenance requirements, low cost, and reliability. It provides a good solution for sustainable energy generation from ambient heat sources. So far, various types of TE materials, including Bi2Te3, SnTe, PbTe, SnSe, etc., have been developed, and most research has been devoted to enhancing the materials’ ZT values using various methods such as nanostructuring, band structure engineering, etc. However, despite recent enhancements in efficiency, major issues with TE power generation technology remain, such as ultralow output voltages and consequent low-energy conversion efficiency, which are rooted in the intrinsic properties of TE materials. As a solution to these challenges, they created negative charges on the dielectric surface on the low temperature which caused the electric potential difference across the two electrodes to increase and achieved the highest output voltage. In addition, the team successfully demonstrated that the wind increased the output voltage without a significant decrease in wind speed through the pinwheel. Prof. Baik said “This research is a new method of energy convergence research that can present a new direction to overcome the limitations of thermoelectric energy-harvesting.” The research team has already applied for two related patents and is developing technologies that reach commercialization through study on non-contact thermoelectric energy-harvesting. This work was supported by the Mid-Career Researcher Program through a National Research Foundation of Korea (NRF) grant funded by the Korean government (NRF2019R1A2C2009822), by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (2019R1A4A1029237), and by the Ministry of Trade, Industry and Energy (MOTIE, 2005721, Korea). It was published in ACS Energy Letters (IF: 19.003, JCR Ranking: 1.852 %), a world-renowned energy journal on February 2021. ※ Paper: Triboelectric Charge-Driven Enhancement of the Output Voltage of BiSbTe-Based Thermoelectric Generators ※ https://doi.org/10.1021/acsenergylett.0c02483 https://www.skku.ac.kr/eng/About/media/news.do?mode=view&articleNo=88733&article.offset=0&articleLimit=10
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- 작성일 2022-01-26
- 조회수 1335
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- [Research] The joint research team led by Professor Sang-Woo Kim developed the world’s first perovskite-based direct current triboe
- The joint research team led by Professor Sang-Woo Kim developed the world’s first perovskite-based direct current triboelectric nanogenerator -The research team succeeded in the development of the world’s first direct current triboelectric nanogenerator by applying dynamic perovskite/CTL heterojunction -The findings can be applied to the charging mechanism for mobile electronic devices and skin wound treatment, etc. in near future [Figure 1] Prof. Sang-Woo Kim of AMSE and Prof. Nam Gyu Park of ChemE Prof. Sang-woo Kim, as the corresponding author, and a Ph.D. candidate Bosung Kim (co-first author) developed the world’s first perovskite-based direct current (DC) triboelectric nanogenerator (TENG) in collaboration with Prof.Park Nam Gyu (corresponding author) of ChemE, Dr. Chunqing Ma (lead author). The TENG converts mechanical energy from external sources into electrical energy through the contact-separation processes. Using micro-movement techniques in which generates electrical output, the TENG can be employed as an energy source for portable electronic devices and as a technology to treat skin wounds leveraging human body movements. Conventional triboelectrification entailed AC (alternating current) signals, which demands an external circuit that leads to the reduction of energy conversion efficiency with bulk system size. Free electrons and holes generated by triboelectrification from the sliding motion can be transferred by the heterojunction, forming DC power output. The phenomenon was first identified by the joint research team led by Prof. Sang-Woo Kim and Prof. Nam Gyu Park. Upon the contact and separating (Sliding) processes, the spiro’s organic hole conductor film placed on the perovskite semiconductor film produces negative and positive charges on the mutual interfaces. The charges migrate to form stable energy levels thermodynamically, resulting in electric current. [Figure 2] Schematic device structure and output analysis. (a) Schematic illustration of the dynamic perovskite/hole transport layer (HTL) heterojunction device. (b) IV curves obtained from the dynamic sliding contact between the FAPbI3 perovskite and the spiro layers, along with static (no sliding movement) condition, measured in the dark (c) voltage and (d) current output of the dynamic perovskite/spiro heterojunction device under continuous sliding movements. Conventional triboelectricity generates AC as the electric current changes along with the contact-separation direction. On the contrary, this triboelectricity follows the principle of charge separation in P/N junction; DC can be generated regardless of the direction of the contact-separation process. Furthermore, the research team demonstrated that light illumination and physical pressure act as stimuli to current output to a large extent. “Dynamic halide perovskite heterojunction that generates DC doesn’t require rectifier to convert AC to DC; thus it can reduce the device size”, said Prof. Nam Gyu Park. “The dynamic halide perovskite heterojunction will perform better than conventional AC triboelectricity when applied to wound treatment that requires micro-electric fields.”, Prof. Sang-woo Kim noted. This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Ministry of Science and ICT (MSIT) of Korea under contracts NRF-2016M3D1A1027663 and NRF-2016M3D1A1027664 (Future Materials Discovery Program) and NRF-2018R1A2A1A19021947 (the Basic Science Research Program). This research was in part supported by Energy Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), funded by the Ministry of Trade, Industry & Energy (No. 20193091010310). ※ Paper title: Dynamic halide perovskite heterojunction generates direct current https://www.skku.edu/skku/campus/skk_comm/news.do?mode=view&articleNo=88053&article.offset=0&articleLimit=10
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- 작성일 2022-01-26
- 조회수 1322