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Takeaki Yajima Last modified date：2024.04.02

Associate Professor / Electronic Devices
Department of Electronics
Faculty of Information Science and Electrical Engineering


Graduate School
Department of Electronics
Graduate School of Information Science and Electrical Engineering
Undergraduate School
Department of Electrical Engineering and Computer Science
School of Engineering


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Homepage
https://kyushu-u.elsevierpure.com/en/persons/takeaki-yajima
　Reseacher Profiling Tool　Kyushu University Pure
https://www.eng.kyushu-u.ac.jp/e/lab_electrical17
Phone
092-802-3759
Fax
092-802-3759
Academic Degree
Doctor (Science)
Country of degree conferring institution (Overseas)
No
Field of Specialization
Oxide thin films, electronic device and circuit, neuromorphic system
Total Priod of education and research career in the foreign country
01years00months
Outline Activities
Research and education on the fields of oxide thin films, electronic devices and circuits, and neuromorphic systems.
Research
Research Interests
  • Edge information processing using small learning circuit
    keyword : echo state network, extreme learning machine, reservoir computing, reinforcement learning
    2022.10.
  • Rhythmic control of switching circuits for low power application
    keyword : neuron circuit, asynchronous, DCDC converter, energy harvesting, analog CMOS
    2020.10.
  • Digital temperature sensor using phase transition materials
    keyword : metal-insulator transition, VO2, vanadium oxide, thermistor, binary
    2020.10.
  • Short-term memory device based on protons and electrons
    keyword : oxide thin film, heterostructure, semiconductor, hydrogen
    2020.10.
Academic Activities
Reports
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1. Energy-saving Electronics Based on the Analogy of Neural Circuits.
Papers
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1. Review of solid-state proton devices for neuromorphic information processing
Abstract

This is a review of proton devices for neuromorphic information processing. While solid-state devices utilizing various ions have been widely studied for non-volatile memory, the proton, which is the smallest ion, has been relatively overlooked despite its advantage of being able to move through various solids at RT. With this advantage, it should be possible to control proton kinetics not only for fast analog memory function, but also for real-time neuromorphic information processing in the same time scale as humans. Here, after briefing the neuromorphic concept and the basic proton behavior in solid-state devices, we review the proton devices that have been reported so far, classifying them according to their device structures. The benchmark clearly shows the time scales of proton relaxation ranges from several milliseconds to hundreds of seconds, and completely match the time scales for expected neuromorphic functions. The incorporation of proton degrees of freedom in electronic devices will also facilitate access to electrochemical phenomena and subsequent phase transitions, showing great promise for neuromorphic information processing in the real-time and highly interactive edge devices..
2. Zero-dimensionality of a scaled-down VO2 metal-insulator transition via high-resolution electrostatic gating.
3. Ultra-low-power switching circuits based on a binary pattern generator with spiking neurons.
4. T. Yajima, T. Tanaka, Y. Samata, K. Uchida, A. Toriumi, High-speed low-energy heat signal processing via digital-compatible binary switch with metal-insulator transitions., International Electron Devices Meeting (IEDM), 10.1109/IEDM19573.2019.8993502, 903-906, 2019.12.
5. T. Yajima, G. Oike, S. Yamaguchi, S. Miyoshi, T. Nishimura, A. Toriumi, Hydrogenation of the wide-gap oxide semiconductor as a room-temperature and 3D-compatible electron doping technique., AIP Advances, 10.1063/1.5055302, 8, 115133, 2018.09.
6. T. Yajima, T. Nishimura, and A, Toriumi, Analog Spike Processing with High Scalability and Low Energy Consumption Using Thermal Degree of Freedom in Phase Transition Materials., VLSI (Technology), 10.1109/VLSIT.2018.8510649, 18, 27-28, 2018.07.
7. Takeaki Yajima, Tomonori Nishimura, Akira Toriumi, Identifying the Collective Length in VO2 Metal-Insulator Transitions, SMALL, 10.1002/smll.201603113, 13, 12, 2017.03.
8. T. Yajima, T. Nishimura, A. Toriumi, Functional Passive Material VO2 for Analogue Signal Processing with High-Speed, Low Power, and Robust Performance, Technical Digest - International Electron Devices Meeting, IEDM, 10.1109/IEDM.2016.7838540, 2016.12.
9. Takeaki Yajima, Go Oike, Tomonori Nishimura, Akira Toriumi, Independent control of phases and defects in TiO2 thin films for functional transistor channels, PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, 10.1002/pssa.201600006, 213, 8, 2196-2202, 2016.08.
10. Takeaki Yajima, Tomonori Nishimura, Akira Toriumi, Positive-bias gate-controlled metal-insulator transition in ultrathin VO2 channels with TiO2 gate dielectrics, NATURE COMMUNICATIONS, 10.1038/ncomms10104, 6, 2015.12.
11. Yajima, Takeaki, Hikita, Yasuyuki, Minohara, Makoto, Bell, Christopher, Mundy, Julia A., Kourkoutis, Lena F., Muller, David A., Kumigashira, Hiroshi, Oshima, Masaharu, Hwang, Harold Y, Controlling band alignments by artificial interface dipoles at perovskite heterointerfaces, Nature Communications, 10.1038/ncomms7759, 2015.06.
12. Takeaki Yajima, Yuma Ninomiya, Tomonori Nishimura, Akira Toriumi, Drastic change in electronic domain structures via strong elastic coupling in VO2 films, PHYSICAL REVIEW B, 10.1103/PhysRevB.91.205102, 91, 20, 2015.05.
13. Yajima, Takeaki, Minohara, Makoto, Bell, Christopher, Kumigashira, Hiroshi, Oshima, Masaharu, Hwang, Harold Y., Hikita, Yasuyuki, Enhanced Electrical Transparency by Ultrathin LaAlO3 Insertion at Oxide Metal/Semiconductor Heterointerfaces, Nano Letters, 10.1021/nl504169m, 2015.02.
14. Takeaki Yajima, Yasuyuki Hikita, Harold Y. Hwang, A heteroepitaxial perovskite metal-base transistor, NATURE MATERIALS, 10.1038/NMAT2946, 10, 3, 198-201, 2011.03.
Presentations
 Show All Presentations >>
1. Neuromorphic device design using oxide phase transition and protons.
2. Neuromorphic Devices Using Oxide Heterostructures and Protons.
3. Neuromorphic Functional Design Using Solid-State Proton Devices.
4. Edge AI using spiking neural networks and its application to energy harvesting.
5. Designing neuromorphic devices using protons.
6. Design of neuromorphic information devices using protons.
7. Trends in Power Supply Circuit Technology for Widespread Use of Energy Harvesting.
Membership in Academic Society
  • THE JAPAN SOCIETY OF APPLIED PHYSICS
  • Material Research Society
  • JAPANESE NEURAL NETWORK SOCIETY
  • JSAP Silicon Technology Devision
  • IEEE
Awards
  • Young Scientist Award by Minister of Education, Culture, Sports, Science and Technology
  • Bachelor Thesis Award
  • Presentation Award
  • Poster Award
  • Graduate Student Award
  • 26th Innovative Frontier Technology Award
  • Young Scientist Award
  • Yasuda Award
  • R & D Encouragement Award
  • Poster Award
  • The 8th Silicon Technology Division Award
  • 40th Japan Society of Applied Physics Paper Award
  • PREST Exchange Meeting, Poster Award
  • Young Researcher Award
  • Excellency in Research in oxide electronics
Educational
Educational Activities
Teaching Fundamentals of Electromagnetism and Application of Quantum Mechanics I for bachelor course. Teaching Neuromorphic Hardware and Group Research Proposal for EEE in graduate school.


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