Updated on 2024/10/07

Information

 

写真a

 
YAJIMA TAKEAKI
 
Organization
Faculty of Information Science and Electrical Engineering Department of Electronics Associate Professor
School of Engineering Department of Electrical Engineering and Computer Science(Concurrent)
Graduate School of Information Science and Electrical Engineering Department of Electrical and Electronic Engineering(Concurrent)
Joint Graduate School of Mathematics for Innovation (Concurrent)
Title
Associate Professor
Contact information
メールアドレス
Tel
0928023759
Profile
Research and education on the fields of oxide thin films, electronic devices and circuits, and neuromorphic systems.
External link

Degree

  • Doctor (Science)

Research History

  • 2012.8~2020.9 東京大学 大学院工学系研究科 マテリアル工学専攻 助教   

Research Interests・Research Keywords

  • Research theme: Edge information processing using small learning circuit

    Keyword: echo state network, extreme learning machine, reservoir computing, reinforcement learning

    Research period: 2022.10

  • Research theme: Rhythmic control of switching circuits for low power application

    Keyword: neuron circuit, asynchronous, DCDC converter, energy harvesting, analog CMOS

    Research period: 2020.10

  • Research theme: Short-term memory device based on protons and electrons

    Keyword: oxide thin film, heterostructure, semiconductor, hydrogen

    Research period: 2020.10

  • Research theme: Digital temperature sensor using phase transition materials

    Keyword: metal-insulator transition, VO2, vanadium oxide, thermistor, binary

    Research period: 2020.10

Awards

  • 文部科学大臣表彰若手科学者賞

    2022.4   文部科学省   Young Scientist Award by Minister of Education, Culture, Sports, Science and Technology

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    電子回路の低消費電力化は最重要課題である。しかし現状シリコンデバイスの優位性が高すぎるあまり既存の枠組みを超えるのが難しく、「異分野融合」が必須である。
    氏は、シリコン技術に、「機能性酸化物」と「神経回路的アーキテクチャ」を導入し、電子回路の低消費電力化技術を構築した。酸化物固有の相転移現象を利用することで低消費電力化と高速化を両立できることを示し、さらに神経回路的アーキテクチャによって無駄な回路動作を排除し消費電力を削減できることを示した。
    本研究成果は、新しい低消費電力化技術として、現実世界とデータ空間をリンクする次世代社会インフラの一翼を担うと期待される。

  • The Oxide Electronics Prize for Excellency in Research

    2019.10   International Workshop on Oxide Electronics   Excellency in Research in oxide electronics

  • SSDM Young Researcher Award

    2019.9   SSDM 2019   Young Researcher Award

  • さきがけ交流会 ポスター賞

    2019.1   科学技術振興機構   PREST Exchange Meeting, Poster Award

  • 第40回 応用物理学会論文賞

    2018.9   日本応用物理学会   40th Japan Society of Applied Physics Paper Award

  • NF基金 研究開発奨励賞

    2017.11   エヌエフ基金   R & D Encouragement Award

  • 応用物理学会 ポスター賞

    2017.9   日本応用物理学会   Poster Award

  • The 8th Silicon Technology Division Award

    2017.9   日本応用物理学会   The 8th Silicon Technology Division Award

  • ゲートスタック研究会 安田賞

    2014.2   第19回ゲートスタック研究会   Yasuda Award

  • 第26回 独創性を拓く 先端技術大賞

    2012.7   フジサインケイビジネスアイ先端技術大賞   26th Innovative Frontier Technology Award

  • PCSI Young Scientist Award

    2012.2   Conference on the Physics and Chemistry of Surfaces and Interfaces   Young Scientist Award

  • MRS Spring, Graduate Student Award

    2011.4   Material Research Society   Graduate Student Award

  • PFシンポジウム ポスター賞

    2011.3   Photon Factory   Poster Award

  • 応用物理学会 講演奨励賞

    2010.9   日本応用物理学会   Presentation Award

  • 東京大学 応用物理学科 卒業論文賞

    2007.3   東京大学 工学部 物理工学科   Bachelor Thesis Award

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Papers

  • Real-time information processing via volatile resistance change in scalable protonic devices

    Satya Prakash Pati, Yifan Geng, Satoshi Hamasuna, Kantaro Fujiwara, Tetsuya Iizuka, Hisashi Inoue, Isao Inoue, Takeaki Yajima

    Communications Materials   5 ( 1 )   2024.12   eISSN:2662-4443

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    Publishing type:Research paper (scientific journal)  

    Biological neural systems operate on multiple time scales, enabling real-time interaction with their environment. However, replicating this in electronic systems is challenging, as scalable devices that operate on similar time scales, particularly from seconds to minutes, are lacking. This study addresses this gap by exploiting proton dynamics to achieve volatile resistance changes over long time scales, and developed a neuromorphic system that can predict biomedical data, such as blood glucose levels, in real time. By applying a low voltage (below 1 V) to a two-terminal device, the Pd electrode hydrogenates or dehydrogenates the mixed conductor WO3, resulting in significant changes in electronic resistance. The device is scalable due to the uniform proton distribution, leading to high impedance and minimal power consumption. Utilizing these volatile protons for short-term memory in an Echo State Network (ESN), this approach demonstrates low-power, efficient real-time information processing, paving the way for future neuromorphic computing applications.

    DOI: 10.1038/s43246-024-00621-1

    Scopus

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  • Review of solid-state proton devices for neuromorphic information processing Invited Reviewed International journal

    Satya Prakash Pati, Takeaki Yajima

    Jpn. J. Appl. Phys.   63 ( 3 )   030801 - 030801   2024.3

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    Language:Others   Publishing type:Research paper (scientific journal)  

    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.

    DOI: 10.35848/1347-4065/ad297b

  • Resonant frequency modulation in inductive vibration power generator via resistive impedance control

    Takeaki Yajima

    IEEE Transactions on Power Electronics   39 ( 1 )   1269 - 1278   2023.12

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    Language:Others   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/tpel.2023.3322704

  • Zero-dimensionality of a scaled-down VO2 metal-insulator transition via high-resolution electrostatic gating Reviewed

    Takeaki Yajima, Yusuke Samata, Satoshi Hamasuna, Satya Prakash Pati, Akira Toriumi

    NPG Asia Materials   15   39-1 - 39-6   2023.6

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    Zero-dimensionality of a scaled-down VO2 metal-insulator transition via high-resolution electrostatic gating

    DOI: 10.1038/s41427-023-00486-9

  • Controlling proton volatility in SiO2-capped TiO2 thin films for neuromorphic functionality

    T. Yajima, S. P. Pati

    Applied Physics Letters   120 ( 24 )   241601 - 241601   2022.6

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    Volatile memories are one of the essential analog devices used in recent electronics, such as neuromorphic circuits and reservoir computing. However, since the application of volatile memories is relatively recent, basic research on the volatility function in the materials is still lacking. In this study, we focused on electrochemically doped protons inside the TiO2 thin film as one of the simplest platforms for volatile functions and aimed to clarify the design principle for volatile memories. It was found that the proton volatility from the TiO2 surface can be controlled by the slow proton diffusion inside a few-nm SiO2 cap layer, where TiO2 and SiO2 can be viewed as a proton container and a sealing cap, respectively. It was further shown that both volatile and nonvolatile protons exist in TiO2 thin films, and hence, suppressing the influence of the latter would be essential for exploiting functions from volatile protons. These results indicate that simple material stacks with nanoscale thickness can control volatile protons in solid-state devices, providing a basic design principle for volatile memories.

    DOI: 10.1063/5.0094481

  • Ultra-low-power switching circuits based on a binary pattern generator with spiking neurons Reviewed International journal

    Takeaki Yajima

    Scientific Reports   12   1150   2022.1

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    Ultra-low-power switching circuits based on a binary pattern generator with spiking neurons

  • Observation of the Pinch‐Off Effect during Electrostatically Gating the Metal‐Insulator Transition Reviewed International journal

    Takeaki Yajima, Akira Toriumi

    Advanced Electronic Materials   8   2100842 - 2100842   2021.11

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    Language:Others   Publishing type:Research paper (scientific journal)  

    DOI: 10.1002/aelm.202100842

  • Regulating phase transformation kinetics via redox reaction in ferroelectric Ge-doped HfO2 Reviewed

    T. Yajima, T. Nishimura, S. Migita, T. Tanaka, K. Uchida, A. Toriumi

    Applied Physics Letters   117 ( 18 )   182902 - 182902   2020.11

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    DOI: 10.1063/5.0028620

  • Modulation of VO 2 Metal–Insulator Transition by Ferroelectric HfO 2 Gate Insulator Reviewed

    Takeaki Yajima, Tomonori Nishimura, Takahisa Tanaka, Ken Uchida, Akira Toriumi

    Advanced Electronic Materials   6 ( 5 )   1901356 - 1901356   2020.5

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    DOI: 10.1002/aelm.201901356

  • High-speed low-energy heat signal processing via digital-compatible binary switch with metal-insulator transitions. Reviewed

    T. Yajima, T. Tanaka, Y. Samata, K. Uchida, A. Toriumi

    International Electron Devices Meeting (IEDM)   903 - 906   2019.12

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    Language:English   Publishing type:Research paper (other academic)  

    High-speed low-energy heat signal processing via digital-compatible binary switch with metal-insulator transitions.

    DOI: 10.1109/IEDM19573.2019.8993502

  • Hydrogenation of the wide-gap oxide semiconductor as a room-temperature and 3D-compatible electron doping technique. Reviewed

    T. Yajima, G. Oike, S. Yamaguchi, S. Miyoshi, T. Nishimura, A. Toriumi

    AIP Advances   8   115133   2018.9

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    Hydrogenation of the wide-gap oxide semiconductor as a room-temperature and 3D-compatible electron doping technique.

    DOI: 10.1063/1.5055302

  • Analog Spike Processing with High Scalability and Low Energy Consumption Using Thermal Degree of Freedom in Phase Transition Materials. Reviewed

    T. Yajima, T. Nishimura, and A, Toriumi

    VLSI (Technology)   18   27 - 28   2018.7

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    Analog Spike Processing with High Scalability and Low Energy Consumption Using Thermal Degree of Freedom in Phase Transition Materials.

    DOI: 10.1109/VLSIT.2018.8510649

  • Identifying the Collective Length in VO2 Metal-Insulator Transitions Reviewed

    Takeaki Yajima, Tomonori Nishimura, Akira Toriumi

    SMALL   13 ( 12 )   2017.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1002/smll.201603113

  • Functional Passive Material VO2 for Analogue Signal Processing with High-Speed, Low Power, and Robust Performance Reviewed International journal

    T. Yajima, T. Nishimura, A. Toriumi

    Technical Digest - International Electron Devices Meeting, IEDM   2016.12

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/IEDM.2016.7838540

  • Independent control of phases and defects in TiO2 thin films for functional transistor channels Reviewed

    Takeaki Yajima, Go Oike, Tomonori Nishimura, Akira Toriumi

    PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE   213 ( 8 )   2196 - 2202   2016.8

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1002/pssa.201600006

  • Positive-bias gate-controlled metal-insulator transition in ultrathin VO2 channels with TiO2 gate dielectrics Reviewed

    Takeaki Yajima, Tomonori Nishimura, Akira Toriumi

    NATURE COMMUNICATIONS   6   2015.12

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1038/ncomms10104

  • Controlling band alignments by artificial interface dipoles at perovskite heterointerfaces Reviewed International journal

    Yajima, Takeaki, Hikita, Yasuyuki, Minohara, Makoto, Bell, Christopher, Mundy, Julia A., Kourkoutis, Lena F., Muller, David A., Kumigashira, Hiroshi, Oshima, Masaharu, Hwang, Harold Y

    Nature Communications   2015.6

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1038/ncomms7759

  • Drastic change in electronic domain structures via strong elastic coupling in VO2 films Reviewed

    Takeaki Yajima, Yuma Ninomiya, Tomonori Nishimura, Akira Toriumi

    PHYSICAL REVIEW B   91 ( 20 )   2015.5

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1103/PhysRevB.91.205102

  • Enhanced Electrical Transparency by Ultrathin LaAlO3 Insertion at Oxide Metal/Semiconductor Heterointerfaces Reviewed International journal

    Yajima, Takeaki, Minohara, Makoto, Bell, Christopher, Kumigashira, Hiroshi, Oshima, Masaharu, Hwang, Harold Y., Hikita, Yasuyuki

    Nano Letters   2015.2

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/nl504169m

  • A heteroepitaxial perovskite metal-base transistor Reviewed

    Takeaki Yajima, Yasuyuki Hikita, Harold Y. Hwang

    NATURE MATERIALS   10 ( 3 )   198 - 201   2011.3

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    DOI: 10.1038/NMAT2946

  • Design of The Ultra-Low-Power Driven VMM Configurations for μW Scale IoT Devices

    Keisuke Takano, Takeaki Yajima, Satoshi Kawakami

    2023 IEEE 16th International Symposium on Embedded Multicore/Many-core Systems-on-Chip (MCSoC)   2023.12

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    DOI: 10.1109/mcsoc60832.2023.00018

  • Long-time-constant leaky-integrating oxygen-vacancy drift-diffusion FET for human-interactive spiking reservoir computing

    Hisashi Inoue, Hiroto Tamura, Ai Kitoh, Xiangyu Chen, Zolboo Byambadorj, Takeaki Yajima, Yasushi Hotta, Tetsuya Iizuka, Gouhei Tanaka, Isao H. Inoue

    2023 IEEE Symposium on VLSI Technology and Circuits (VLSI Technology and Circuits)   2023.6

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    DOI: 10.23919/vlsitechnologyandcir57934.2023.10185412

  • CMOS-based area-and-power-efficient neuron and synapse circuits for time-domain analog spiking neural networks Reviewed

    Xiangyu Chen, Zolboo Byambadorj, Takeaki Yajima, Hisashi Inoue, Isao H. Inoue, Tetsuya Iizuka

    Applied Physics Letters   122   074102   2023.2

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    CMOS-based area-and-power-efficient neuron and synapse circuits for time-domain analog spiking neural networks

    DOI: 10.1063/5.0136627

  • An ultra-compact leaky integrate-and-fire neuron with long and tunable time constant utilizing pseudo resistors for spiking neural networks

    Xiangyu Chen, Takeaki Yajima, Isao H. Inoue, Tetsuya Iizuka

    Japanese Journal of Applied Physics   61 ( SC )   SC1051 - SC1051   2022.5

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    Abstract

    Spiking neural networks (SNNs) inspired by biological neurons enable a more realistic mimicry of the human brain. To realize SNNs similar to large-scale biological networks, neuron circuits with high area efficiency are essential. In this paper, we propose a compact leaky integrate-and-fire (LIF) neuron circuit with a long and tunable time constant, which consists of a capacitor and two pseudo resistors (PRs). The prototype chip was fabricated with TSMC 65 nm CMOS technology, and it occupies a die area of 1392 μm2. The fabricated LIF neuron has a power consumption of 6 μW and a leak time constant of up to 1.2 ms (the resistance of PR is up to 600 MΩ). In addition, the time constants are tunable by changing the bias voltage of PRs. Overall, this proposed neuron circuit facilitates the very-large-scale integration of adaptive SNNs, which is crucial for the implementation of bio-scale brain-inspired computing.

    DOI: 10.35848/1347-4065/ac43e4

  • Self-synchronized Rectifier with Phase Information Extracted from Vibration Energy Harvester Reviewed

    Hang Yin, Takeaki Yajima

    Sensors and Materials   34 ( 5 )   1899 - 1907   2022.5

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    DOI: 10.18494/SAM3863

  • Atomistic simulation study of impacts of surface carrier scatterings on carrier transport in Pt nanosheets Reviewed

    Takahisa Tanaka, Taro Kato, Takeaki Yajima, Ken Uchida

    IEEE Electron Device Letters   1057 - 1060   2021.5

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    DOI: 10.1109/led.2021.3077466

  • Temperature dependence of resistivity increases induced by thiols adsorption in gold nanosheets

    Taro Kato, Takahisa Tanaka, Takeaki Yajima, Ken Uchida

    Japanese Journal of Applied Physics   60 ( SB )   SBBH13 - SBBH13   2021.2

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    Temperature dependence of resistivity increases induced by thiols adsorption in gold nanosheets

    DOI: 10.35848/1347-4065/abd6de

  • Impact of defects in self-assembled monolayer on humidity sensing by molecular functionalized transistors Reviewed

    T. Tanaka, T. Yajima, K. Uchida

    Jpn. J. Appl. Phys.   2020.3

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    Impact of defects in self-assembled monolayer on humidity sensing by molecular functionalized transistors

  • Understanding of Fermi level pinning at metal/germanium interface based on semiconductor structure Reviewed

    X. Lu, T. Nishimura, T. Yajima, A. Toriumi

    APEX   13   031003   2020.3

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    Understanding of Fermi level pinning at metal/germanium interface based on semiconductor structure

  • Reaction of GeO2 with Ge and crystallization of GeO2 on Ge Reviewed

    M. Xie, T. Nishimura, T. Yajima, A. Toriumi

    J. Appl. Phys.   127   024101   2020.2

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    Reaction of GeO2 with Ge and crystallization of GeO2 on Ge

  • Electron‐Doping Mottronics in Strongly Correlated Perovskite Reviewed

    J. Chen, W. Mao, L. Gao, F. Yan, T. Yajima, N. Chen, Z. Chen, H. Dong, B. Ge, P. Zhang, X. Cao, M. Silde, Y. Jiang, T. Terai, J. Shi

    Adv. Mater.   32 ( 6 )   1905060   2019.12

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    Electron‐Doping Mottronics in Strongly Correlated Perovskite

  • Heteroepitaxial vertical perovskite hot-electron transistors down to the monolayer limit. Reviewed

    B. Kim, Y. Hikita, T. Yajima, H. Hwang

    Nature Commun.   10   5312   2019.12

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    Heteroepitaxial vertical perovskite hot-electron transistors down to the monolayer limit.

  • Almost pinning-free bismuth/Ge and/Si interfaces Reviewed

    Tomonori Nishimura, Xuan Luo, Soshi Matsumoto, Takeaki Yajima, Akira Toriumi

    AIP ADVANCES   9 ( 9 )   2019.9

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    In this work, we investigated the band alignment at bismuth (Bi)/germanium (Ge) and Bi/silicon (Si) interfaces to understand the mechanism of strong Fermi level pinning (FLP) at element metal/Ge and/Si interfaces. Bi/Ge and/Si interfaces exhibit almost ideal alignment deviating from the trend of strong FLP at element metal/Ge and/Si interfaces. This result suggests that the strong FLP at element metal/Ge and/Si interfaces is mainly caused by the metal-induced gap states (MIGS) in case of the free electron density of metal, and that the weak FLP at direct metal/Ge and/Si interfaces including germanide/Ge and silicide/Si interfaces is comprehensively understandable from the MIGS in case of low electron density. Furthermore, we also discuss impacts of interface structures on the band alignment at the MIGS-weakened interface.

    DOI: 10.1063/1.5115535

  • Delta-temperatural electronic transportation achieved in metastable perovskite rare-earth nickelate thin films Reviewed

    Chen Jikun, Hu Haiyang, Yajima Takeaki, Wang Jiaou, Ge Binghui, Dong Hongliang, Jiang Yong, Chen Nuofu

    JOURNAL OF MATERIALS CHEMISTRY C   7 ( 26 )   8101 - 8108   2019.7

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    Delta-temperatural electronic transportation achieved in metastable perovskite rare-earth nickelate thin films

    DOI: 10.1039/c9tc02327e

  • Overcoming synthetic metastabilities and revealing metal-to-insulator transition & thermistor bi-functionalities for d-band correlation perovskite nickelates Reviewed

    Chen Jikun, Hu Haiyang, Wang Jiaou, Yajima Takeaki, Ge Binghui, Ke Xinyou, Dong Hongliang, Jiang Yong, Chen Nuofu

    MATERIALS HORIZONS   6 ( 4 )   788 - 795   2019.4

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    Overcoming synthetic metastabilities and revealing metal-to-insulator transition & thermistor bi-functionalities for d-band correlation perovskite nickelates

    DOI: 10.1039/c9mh00008a

  • Inhomogeneous barrier heights at dipole-controlled SrRuO3/Nb:SrTiO3 Schottky junctions Reviewed

    T. Yajima, M. Minohara, C. Bell, H. Y. Hwang, Y. Hikita

    Applied Physics Letters   11   221603   2018.11

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    DOI: 10.1063/1.5052712

  • Anomalous Spectral Shape Evolution of Ge Raman Shift in Oxidation of SiGe. Reviewed

    Y Noma, W Song, T Nishimura, T Yajima, A Toriumi

    IEEE Electron Devices Technology and Manufacturing (EDTM)   2018.3

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    Anomalous Spectral Shape Evolution of Ge Raman Shift in Oxidation of SiGe.

    DOI: 10.1109/EDTM.2018.8421461

  • Strain Tuning in Complex Oxide Epitaxial Films Using an Ultrathin Strontium Aluminate Buffer Layer Reviewed

    Di Lu, Yasuyuki Hikita, David J. Baek, Tyler A. Merz, Hiroki Sato, Bongju Kim, Takeaki Yajima, Christopher Bell, Arturas Vailionis, Lena F. Kourkoutis, Harold Y. Hwang

    Physica Status Solidi - Rapid Research Letters   12 ( 3 )   2018.3

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    A reliable method to apply biaxial strain over a wide range of values with minimal dislocation generation is critical for the study of strain dependent physical properties in oxide thin films and heterostructures. In this work, we systematically controlled the strain state in a perovskite manganite thin film by as much as 1% using a new ultrathin strain-releasing buffer layer Sr3Al2O6, and observed signatures of accompanying magnetic and metal–insulator transitions. The near-zero strain state is achieved within five nanometers of buffer layer thickness, substantially thinner than any oxide epitaxial buffer layers that can continuously tune the film strain states. Furthermore, the majority of misfit dislocations were confined to the Sr3Al2O6 layer, structurally decoupling defects in the film from the substrate.

    DOI: 10.1002/pssr.201700339

  • Rigidity enhancement of GeO2by Y doping for reliable Ge gate stacks Reviewed

    Tomonori Nishimura, Xiaoyu Tang, Takeaki Yajima, Akira Toriumi

    Electron Devices Technology and Manufacturing Conference (EDTM)   2018.3

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    Rigidity enhancement of GeO2by Y doping for reliable Ge gate stacks

    DOI: 10.1109/EDTM.2018.8421529

  • Potential Influence of Surface Atomic Disorder on Fermi-level Pinning at Metal/SiGe Interface Reviewed

    X Luo, T Nishimura, T Yajima, A Toriumi

    Electron Devices Technology and Manufacturing (EDTM)   2018.3

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    Potential Influence of Surface Atomic Disorder on Fermi-level Pinning at Metal/SiGe Interface

    DOI: 10.1109/EDTM.2018.8421410

  • Evolution of ferroelectric HfO2 in ultrathin region down to 3 nm Reviewed

    Xuan Tian, Shigehisa Shibayama, Tomonori Nishimura, Takeaki Yajima, Shinji Migita, Akira Toriumi

    Applied Physics Letters   112 ( 10 )   2018.3

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    The ferroelectric properties of ultrathin Y-doped HfO2 films were investigated. Ferroelectricity was demonstrated experimentally in 3 nm-thick Y-doped HfO2 via direct detection of displacement currents during polarization switching. The dependence on the HfO2 thickness within the 30 to 3 nm range revealed that the ferroelectric properties decrease rapidly below a critical thickness. In the ultrathin HfO2 region, methods such as higher Y doping or metal capping annealing were required to further stabilize the ferroelectric phase. These methods could be used to enhance the switchable polarization (Psw) to 35 μC/cm2 in 5 nm- and 10 μC/cm2 in 3 nm-thick Y-doped HfO2. This paper indicates that HfO2 ferroelectricity is scalable even in the ultrathin region.

    DOI: 10.1063/1.5017094

  • Sub-nm EOT ferroelectric HfO2 on p+Ge with highly reliable field cycling properties Reviewed

    X. Tian, L. Xu, S. Shibayama, T. Nishimura, T. Yajima, S. Migita, A. Toriumi

    Technical Digest - International Electron Devices Meeting, IEDM   17   37.1.1 - 37.1.4   2018.1

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    5-nm-Thick ferroelectric Y-doped HfO2 was intensively studied. The thickness dependence of ferroelectric properties indicates that stable ferroelectric characteristics are maintained down to 5-nm-thick by taking care of doping and capping effects. Furthermore, the cycling performance shows no wake-up behavior, no obvious degradation after 108 cycles. These results not only enable us to use ferroelectric HfO2 for practical application, but also point out intrinsic properties in ultrathin ferroelectric HfO2 film from materials science point of view.

    DOI: 10.1109/IEDM.2017.8268508

  • Dipole-correlated carrier transportation and orbital reconfiguration in strain-distorted SrNbxTi1-xO3/KTaO3 Reviewed

    Jikun Chen, Xinyou Ke, Jiaou Wang, Takeaki Yajima, Haijie Qian, Song Sun

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   19 ( 44 )   29913 - 29917   2017.11

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    Strong electron-correlations can result in un-conventional transportation behaviour, such as metalinsulator transitions, high temperature superconductivity and bad metal conduction. Here we report a distinct transportation characteristic achieved by actively coupling the carriers with randomly distributed lattice-dipoles for strain-distorted SrNbxTi1-xO3. The strong electron correlations split the conduction band, and lead to a distinguished thermal-emitted carrier transportation with an activation energy of similar to 10(-2) eV. Further consistency was demonstrated by the respective changes in orbital configurations observed in near edge X-ray absorption fine structures. The present investigation demonstrates new mechanisms for regulating the carrier transportation using polaronic electron correlations.

    DOI: 10.1039/c7cp06495k

  • Reconsideration of Metal Work Function at Metal/Semiconductor Interface Reviewed

    Nishimura Tomonori, Yajima Takeaki, Toriumi Akira

    SEMICONDUCTOR PROCESS INTEGRATION 10   80 ( 4 )   107 - 112   2017.10

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    Reconsideration of Metal Work Function at Metal/Semiconductor Interface
    Fermi-level pinning (FLP) at metal/semiconductor interface, which is deviated from ideal Schottky-Mott limit, has been discussed for several decades based on various intrinsic and extrinsic models, and it has commonly been considered that the origin of FLP is ascribed only to semiconductor side. In this paper, we discuss FLP from the viewpoint of work function of metal. We focus on a fact that both of surface term of vacuum work function at metal/vacuum interface and intrinsic metal induced gap states (MIGS) at metal/semiconductor interface are described as a common physics of wave function tailing from metal. This suggests that the MIGS is regarded as a surface term of work function of metal at metal/semiconductor interface rather than interface states. Namely, the FLP caused by MIGS seems corresponded to modulation of work function. We also discuss how to control the work function modulation from both semiconductor and metal sides taking germanium as an example.

    DOI: 10.1149/08004.0107ecst

  • Kinetic pathway of the ferroelectric phase formation in doped HfO2 films Reviewed

    Lun Xu, Tomonori Nishimura, Shigehisa Shibayama, Takeaki Yajima, Shinji Migita, Akira Toriumi

    JOURNAL OF APPLIED PHYSICS   122 ( 12 )   2017.9

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    The dopant-induced ferroelectric HfO2 formation has been systematically investigated by using cation (Sc, Y, Nb, Al, Si, Ge, and Zr) and anion (N) dopants. Both differences and similarities are discussed among various dopants by focusing on two major factors, the oxygen vacancy (Vo) and the dopant ionic size. First, the doping concentration dependence of the remanent polarization in 27 (+/-2) nm HfO2 films is quantitatively estimated. Then, by comparing the polarization result with the structural transformation in doped HfO2, the pathway of the dopant-induced HfO2 phase transition is discussed among monoclinic, ferroelectric orthorhombic, tetragonal, and cubic phases. Finally, it is addressed that a dopant species independent phase transition route may exist in HfO2 owing to the same kinetic transition process, in which the ferroelectric phase seems to be at an intermediate state between tetragonal and monoclinic phases. Published by AIP Publishing.

    DOI: 10.1063/1.5003918

  • Thermal oxidation kinetics of germanium Reviewed

    X. Wang, T. Nishimura, T. Yajima, A. Toriumi

    APPLIED PHYSICS LETTERS   111 ( 5 )   052101   2017.7

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    Thermal oxidation kinetics of Ge was investigated by the O-18 tracing study and re-oxidation experiments of the SiO2/GeO2 stacked oxide-layer. The results suggest that Ge oxidation kinetics is completely different from that expected from the Deal-Grove model and that Ge is oxidized by GeO2 on Ge instead of O-2 at the interface. This oxidation process forms large amounts of oxygen vacancies in GeO2, which facilitate the diffusion of oxygen atoms in GeO2. This means that oxygen atoms diffuse through GeO2 with an exchange type of process. Based on experimental results, a possible kinetics for Ge oxidation is discussed. Published by AIP Publishing.

    DOI: 10.1063/1.4997298

  • n(+)Si/pGe Heterojunctions Fabricated by Low Temperature Ribbon Bonding With Passivating Interlayer Reviewed

    Tony Chi Liu, Shoichi Kabuyanagi, Tomonori Nishimura, Takeaki Yajima, Akira Toriumi

    IEEE ELECTRON DEVICE LETTERS   38 ( 6 )   716 - 719   2017.6

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    A bonding technique via passivating interlayer formation is proposed for bulkmaterial heterojunction fabrication. n(+)Si/pGe heterojunctions were fabricated by a ribbon bonding with interfaces passivated by an amorphous interlayer. With a highest process temperature as low as 150. degrees C, the bonded junctions exhibited rectifying characteristics with a turn-on voltage of 0.3 V as an ideal Si/Ge heterojunction and an ideality factor of 2.15. This technique shows a great potential for bulk material heterojunction formation, especially when ultimately abrupt junctions and low temperature processes are needed.

    DOI: 10.1109/LED.2017.2699658

  • Thermodynamic understanding and analytical modeling of interfacial SiO2 scavenging in HfO2 gate stacks on Si, SiGe, and SiC Reviewed

    Xiuyan Li, Takeaki Yajima, Tomonori Nishimura, Akira Toriumi

    APPLIED PHYSICS LETTERS   110 ( 14 )   2017.4

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    This work thermodynamically and experimentally generalizes the interfacial SiO2 scavenging in HfO2 gate stacks from on Si to on other channel materials including SiGe and SiC and proposes a generalized formulation for this process. By paying attention to the Si chemical potential in the SiO2 interfacial layer (SiO2-IL) significantly affected by the substrate, it clarifies that Si in the substrate is indispensable to trigger the scavenging process. Thanks to this understanding, we demonstrate that the scavenging is extendable to next generation of channel materials containing Si such as SiGe and SiC with well-controlled high-k gate stacks. In addition, via formulating the diffusion-reaction-diffusion kinetics, an analytical relation like the Deal-Grove model is obtained for SiO2-IL scavenging in high-k gate stacks. Published by AIP Publishing.

    DOI: 10.1063/1.4979711

  • Ultrahigh Thermoelectric Performance in SrNb0.2Ti0.8O3 Oxide Films at a Submicrometer-Scale Thickness Reviewed

    Jikun Chen, Hongyi Chen, Feng Hao, Xinyou Ke, Nuofu Chen, Takeaki Yajima, Yong Jiang, Xun Shi, Kexiong Zhou, Max Dobeli, Tiansong Zhang, Binghui Ge, Hongliang Dong, Huarong Zeng, Wenwang Wu, Lidong Chen

    ACS ENERGY LETTERS   2 ( 4 )   915 - 921   2017.4

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    Localized refrigeration and power generation via thermoelectric technology rely on efficient thermoelectric materials with high performance at room temperature. Although the two-dimensional electron gas (2DEG)-related materials exhibit ultrahigh thermoelectric performance near room temperature, such performance is only preserved at thicknesses within subnanometer scales, limited by the requirement of two-dimensional size confinements. Here we report ultrahigh thermoelectric performance similar to 2DEG-related materials but achieved in SrNb0.2Ti0.8O3 oxide films with a submicrometer-scale thickness by regulating strain induced lattice polarizations and interfacial polarizations. A large figure of merit, zT, and power factor (similar to 10(2)-10(3) mu W cm(-1) K-2) were achieved near room temperature, and the maximum zT is estimated to be similar to 1.6 for a 49 nm thick film. These performances exceed those of the existing n-type thermoelectric materials for room-temperature uses and the reported best oxide materials beyond subnanometer scales. The earth-abundant elemental composition of the oxide film paves the way toward potential applications in thermoelectric thin film devices with a microscale thickness.

    DOI: 10.1021/acsenergylett.7b00197

  • General relationship for cation and anion doping effects on ferroelectric HfO2 formation Reviewed

    L. Xu, S. Shibayama, K. Izukashi, T. Nishimura, T. Yajima, S. Migita, A. Toriumi

    Technical Digest - International Electron Devices Meeting, IEDM   25.2.1 - 25.2.4   2017.1

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    This work discusses the general relationship for cation and anion doping effects on the HfO2 para-/ferroelectric transition, which will provide us a helpful instruction for precise HfO2 ferroelectricity design. In addition, ferroelectric N-doped HfO2 has been demonstrated as a gate dielectric film on an oxide semiconductor for ferroelectric field-effect transistors (FeFETs).

    DOI: 10.1109/IEDM.2016.7838477

  • General relationship for cation and anion doping effects on ferroelectric HfO2 formation Reviewed International journal

    L. Xu, S. Shibayama, K. Izukashi, T. Nishimura, T. Yajima, S. Migita, A. Toriumi

    Technical Digest - International Electron Devices Meeting, IEDM   2016.12

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    DOI: 10.1109/IEDM.2016.7838477

  • Ferroelectric phase stabilization of HfO2 by nitrogen doping Reviewed

    Lun Xu, Tomonori Nishimura, Shigehisa Shibayama, Takeaki Yajima, Shinji Migita, Akira Toriumi

    APPLIED PHYSICS EXPRESS   9 ( 9 )   2016.9

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    We report that nitrogen (N) doping can drive the ferroelectricity of HfO2. It was found that N doping can cause the transition from a monoclinic phase to a highly symmetric phase. The role of N doping is discussed from the viewpoints of charge balance and bond-constraining effects. The former is responsible for the structural transformation from a paraelectric phase to a ferroelectric phase by forming an oxygen vacancy. In addition, Hf-N and N-O bonds with covalent characteristics have strong effects on HfO2 structural and electrical properties, and thus contribute to a marked HfO2 para-/ferroelectric transition. (C) 2016 The Japan Society of Applied Physics

    DOI: 10.7567/APEX.9.091501

  • Anomalous electrical properties of Au/SrTiO3 interface Reviewed

    Lun Xu, Takeaki Yajima, Tomonori Nishimura, Akira Toriumi

    JAPANESE JOURNAL OF APPLIED PHYSICS   55 ( 8 )   2016.8

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    Metal/dielectric interface properties of Au/SrTiO3 (STO) and SrRuO3/SrTiO3 (SRO/STO) interfaces were investigated using metal/STO/heavily Nb-doped STO (0.5 wt% Nb:STO) capacitors. The observed interfacial capacitance at SRO/STO accords with results predicted theoretically, whereas that at the Au/STO interface is strongly suppressed, suggesting an intrinsic low-k (dielectric constant) interfacial layer formation at the Au/STO interface owing to in situ evaporated Au after STO film deposition. Furthermore, metal/0.01 wt% Nb:STO junctions were also analyzed. It was found that the SRO/Nb: STO junction forms an ideal Schottky dipole, whereas the Au/Nb: STO junction exhibits anomalous electrical properties. (C) 2016 The Japan Society of Applied Physics

    DOI: 10.7567/JJAP.55.08PB04

  • Reexamination of Fermi level pinning for controlling Schottky barrier height at metal/Ge interface Reviewed

    Tomonori Nishimura, Takeaki Yajima, Akira Toriumi

    APPLIED PHYSICS EXPRESS   9 ( 8 )   2016.8

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    The element metal/germanium (Ge) interface exhibits a strong Fermi level pinning (FLP), which is usually characterized on the basis of Ge side semiconductor properties. In this work, we demonstrate that metal properties significantly affect the Schottky barrier height (SBH) on Ge. Metallic germanides show both FLP alleviation and a clear substrate orientation dependence of SBH on Ge, despite the nearly perfect FLP and very slight orientation dependence in the element metal case. As a result, ohmic characteristics are observed at germanide/n-Ge (111) junctions. The metal properties required to alleviate the FLP on Ge are also discussed. (C) 2016 The Japan Society of Applied Physics

    DOI: 10.7567/APEX.9.081201

  • Ferroelectricity of nondoped thin HfO2 films in TiN/HfO2/TiN stacks Reviewed

    Tomonori Nishimura, Lun Xu, Shigehisa Shibayama, Takeaki Yajima, Shinji Migita, Akira Toriumi

    JAPANESE JOURNAL OF APPLIED PHYSICS   55 ( 8 )   2016.8

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    We report on the impact of TiN interfaces on the ferroelectricity of nondoped HfO2. Ferroelectric properties of nondoped HfO2 in TiN/HfO2/TiN stacks are shown in capacitance-voltage and polarization-voltage characteristics. The Curie temperature is also estimated to be around 500 degrees C. The ferroelectricity of nondoped HfO2 clearly appears by thinning HfO2 film down to > 35 nm. We directly revealed in thermal treatments that the ferroelectric HfO2 film on TiN was maintained by covering the top surface of HfO2 with TiN, while it was followed by a phase transition to the paraelectric phase in the case of the open surface of HfO2. Thus, it is concluded that the ferroelectricity in nondoped HfO2 in this study was mainly driven by both of top and bottom TiN interfaces. (C) 2016 The Japan Society of Applied Physics

    DOI: 10.7567/JJAP.55.08PB01

  • Recent Progress of Junction Technology for Germanium CMOS Reviewed

    Tomonori Nishimura, Choong Hyun Lee, Toshimitsu Nakamura, Takeaki Yajima, Kosuke Nagashio, Koji Kita, Akira Toriumi

    2015 15TH INTERNATIONAL WORKSHOP ON JUNCTION TECHNOLOGY (IWJT)   65 - 68   2016.5

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    To realize scaled Ge CMOS device, there are several challenges of junction formation in nMOSFET. (Fermi level pinning, activation and diffusion of n-type impurities and junction leakage, etc.) In this paper, we report recent progresses of controllability of band alignment at metal/Ge interface, understanding of n-type impurity activation in Ge, and impact of oxygen in Ge on n(+)/p junction leakage.

    DOI: 10.1109/IWJT.2015.7467098

  • Experimental evidence of zone-center optical phonon softening by accumulating holes in thin Ge Reviewed

    Shoichi Kabuyanagi, Tomonori Nishimura, Takeaki Yajima, Akira Toriumi

    AIP ADVANCES   6 ( 1 )   2016.1

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    We discuss the impact of free carriers on the zone-center optical phonon frequency in germanium (Ge). By taking advantage of the Ge-on-insulator structure, we measured the Raman spectroscopy by applying back-gate bias. Phonon softening by accumulating holes in Ge film was clearly observed. This fact strongly suggests that the phonon softening in heavily-doped Ge is mainly attributed to the free carrier effect rather than the dopant atom counterpart. Furthermore, we propose that the free carrier effect on phonon softening is simply understandable from the viewpoint of covalent bonding modification by free carriers. (C) 2016 Author(s).

    DOI: 10.1063/1.4941072

  • Gate-bias dependent phonon softening observed in Ge MOSFETs Reviewed

    Shoichi Kabuyanagi, Tomonori Nishimura, Takeaki Yajima, Akira Toriumi

    ECS Transactions   69 ( 10 )   75 - 80   2015.10

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    We investigate impacts of free carriers on phonon frequency of zone-center optical phonon in Germanium (Ge). By taking advantage of Ge-on-insulator structure, Raman measurement with applying the back-gate bias was performed. The phonon softening was clearly observed by increasing hole density. It is also pointed out that the phonon softening in heavily-doped Ge is mainly attributed to the free carrier effect rather than dopant atom one. Furthermore, we show that the free carrier effect on phonon softening can be simply and reasonably interpreted from the view point of modification of the covalent bonding by free carriers.

    DOI: 10.1149/06910.0075ecst

  • Significance of Kinetic-linkage of Oxygen Vacancy with SiO2/Si Interface for SiO2-IL Scavenging in HfO2 Gate Stacks Reviewed

    Xiuyan Li, Takeaki Yajima, Tomonori Nishimura, Akira Toriumi

    2015 SILICON NANOELECTRONICS WORKSHOP (SNW)   2015.9

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    This work clarifies roles of substrate-Si in SiO2-IL scavenging in HfO2/SiO2/Si gate stack experimentally, and points out a coupling effect of oxygen vacancy (V-O) with SiO2/Si interface from thermodynamic viewpoint.

  • Study of Si kinetics in interfacial SiO2 scavenging in HfO2 gate stacks Reviewed

    Xiuyan Li, Takeaki Yajima, Tomonori Nishimura, Akira Toriumi

    APPLIED PHYSICS EXPRESS   8 ( 6 )   2015.6

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    In this study, what occurs at the SiO2/substrate interface and how Si atoms in SiO2 behave in interfacial SiO2 scavenging in a HfO2 gate stack have been investigated. Since the same scavenging occurs on both Si and SiC substrates, the SiC substrate is used to study the role of the substrate. The characterizations of the SiO2/SiC interface show no Si growth on the substrate and no consumption of the substrate in the SiO2 scavenging. Isotope tracing experiments for a HfO2/SiO2/Si stack further demonstrate that atomic Si is generated in scavenging and diffuses out through the HfO2 layer. On the basis of these findings, the reaction at the SiO2/substrate interface is thermodynamically discussed. (C) 2015 The Japan Society of Applied Physics

    DOI: 10.7567/APEX.8.061304

  • Effect of Free Carrier Accumulation or Depletion on Zone-center Vibrational Mode in Ge Reviewed

    Shoichi Kabuyanagi, Tomonori Nishimura, Takeaki Yajima, Akira Toriumi

    2015 SILICON NANOELECTRONICS WORKSHOP (SNW)   2015.6

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  • Nondestructive characterization of oxide/germanium interface by direct-gap photoluminescence analysis Reviewed

    Shoichi Kabuyanagi, Tomonori Nishiumura, Takeaki Yajima, Akira Toriumi

    APPLIED PHYSICS EXPRESS   8 ( 5 )   2015.5

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    We demonstrate that direct-gap photoluminescence (PL) analysis is useful for the nondestructive, fast, and in-line characterization of the oxide/germanium (Ge) interface without making actual devices. The fact that Ge has a quasi-direct gap enables us to utilize direct-gap PL intensity as a good indicator for interface quality estimation. We experimentally confirm the validity of the present analysis, by comparing PL spectra with capacitance-voltage characteristics. The impact of the band bending at the interface on PL intensity is also discussed. Furthermore, the effect of forming gas annealing at oxide/Ge interfaces is discussed by taking advantage of the present method. (C) 2015 The Japan Society of Applied Physics

    DOI: 10.7567/APEX.8.051301

  • Analytical Formulation of SiO<inf>2</inf>-IL scavenging in HfO<inf>2</inf>/SiO<inf>2</inf>/Si gate stacks - A key is the SiO<inf>2</inf>/Si interface reaction Reviewed

    Xiuyan Li, Takeaki Yajima, Tomonori Nishimura, Kosuke Nagashio, Akira Toriumi

    Technical Digest - International Electron Devices Meeting, IEDM   2015- ( February )   21.2.1 - 21.2.4   2015.2

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    The scavenging kinetics of ultra-thin-SiO&lt
    inf&gt
    2&lt
    /inf&gt
    interface layer (IL) in HfO&lt
    inf&gt
    2&lt
    /inf&gt
    /SiO&lt
    inf&gt
    2&lt
    /inf&gt
    /Si stacks is investigated by focusing on SiO&lt
    inf&gt
    2&lt
    /inf&gt
    /Si interface reaction in addition to both O and Si atom kinetics. SiO&lt
    inf&gt
    2&lt
    /inf&gt
    /Si interface serves as a stage that the oxygen vacancy (VO) is converted to Si release from SiO&lt
    inf&gt
    2&lt
    /inf&gt
    with the help of Si substrate. Based on both diffusion kinetics and possible reaction, an analytical model for two-stage SiO&lt
    inf&gt
    2&lt
    /inf&gt
    -IL scavenging in high-k gate stack is proposed.

    DOI: 10.1109/IEDM.2014.7047094

  • Effect of Si substrate on interfacial SiO2 scavenging in HfO2/SiO2/Si stacks Reviewed

    Xiuyan Li, Takeaki Yajima, Tomonori Nishimura, Kosuke Nagashio, Akira Toriumi

    APPLIED PHYSICS LETTERS   105 ( 18 )   2014.11

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    The scavenging kinetics of an ultra-thin SiO2 interface layer (SiO2-IL) in an HfO2/SiO2/Si stack is discussed by focusing on the substrate effect in addition to oxygen diffusion. O-18 tracing experiments demonstrate that the O-atom moves from the SiO2-IL to the HfO2 layer during scavenging. SiO2-IL scavenging with various substrates (Si, SiC, and sapphire) has been found to be significantly different, which suggests that the Si in the substrate is also necessary to continuously cause the scavenging. Based on these findings and thermodynamic considerations, a kinetic model where oxygen vacancy (VO) transferred from the HfO2 reacts with the SiO2, which is in contact with the Si-substrate, is proposed for the SiO2-IL scavenging. (C) 2014 AIP Publishing LLC.

    DOI: 10.1063/1.4901172

  • Atomic-scale Planarization of Ge (111), (110) and (100) Surfaces Reviewed

    Tomonori Nishimura, ChoongHyun Lee, Takeaki Yajima, Kosuke Nagashio, Akira Toriumi

    2014 7TH INTERNATIONAL SILICON-GERMANIUM TECHNOLOGY AND DEVICE MEETING (ISTDM)   127 - 128   2014.8

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    DOI: 10.1109/ISTDM.2014.6874698

  • Kinetic Model for Scavenging of SiO2 Interface Layer in HfO2 Gate Stacks Reviewed

    Xiuyan Li, Takeaki Yajima, Tomonori Nishimura, Kosuke Nagashio, Akira Toriumi

    2014 IEEE SILICON NANOELECTRONICS WORKSHOP (SNW)   2014.6

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    This work discusses effects of the substrate on the scavenging of SiO2 interface layer (SiO2-IL) in HfO2 gate stacks. We propose a model that SiO2-IL scavenging occurs through the reaction of the oxygen vacancy (V-O) transferred from HfO2 to SiO2 with oxygen formed at SiO2/substrate interface.

    DOI: 10.1109/SNW.2014.7348532

  • Atomically flat planarization of Ge(100), (110), and (111) surfaces in H-2 annealing Reviewed

    Tomonori Nishimura, Shoichi Kabuyanagi, Wenfeng Zhang, Choong Hyun Lee, Takeaki Yajima, Kosuke Nagashio, Akira Toriumi

    APPLIED PHYSICS EXPRESS   7 ( 5 )   2014.5

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    We demonstrate that Ge(100), (110), and (111) Ge surfaces are planarized with atomic level step and terrace structures in H-2 annealing. The temperature required for such planarization is different among the three orientations. The step edge structure on the Ge(100) surface is composed of alternate smooth and rough steps (S-a + S-b steps) owing to the (2 x 1) reconstruction on that surface. It is also shown that the terrace widths on the Ge(110) and (111) surfaces are on average controlled by adjusting the off-angle from the respective surface orientation. (C) 2014 The Japan Society of Applied Physics

    DOI: 10.7567/APEX.7.051301

  • HfO2-assisted SiO2 reduction in HfO2/SiO2/Si stacks Reviewed

    Xiuyan Li, Takeaki Yajima, Tomonori Nishimura, Kosuke Nagashio, Akira Toriumi

    THIN SOLID FILMS   557   272 - 275   2014.4

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    The ultra-thin SiO2 interface layer (SiO2-IL) in the HfO2/SiO2/Si stack was found to be reduced during the ultra-high vacuum (UHV) annealing. Along with thin SiO2-IL reduction in UHV, SiO desorption and silicide formation also took place. The thermal desorption spectroscopy and X-ray photoelectron spectroscopy results showed that the SiO2-IL reduction occurred at temperatures lower than the temperature showing SiO desorption and silicidation by accurately controlling the annealing conditions. The mechanism of SiO2-IL reduction can be explained by the oxygen diffusion through oxygen vacancies in HfO2 generated in the gate stack formation and thermal treatment. It is also understandable that the silicidation process is associated with the inhomogeneous SiO desorption. (c) 2013 Elsevier B. V. All rights reserved.

    DOI: 10.1016/j.tsf.2013.10.142

  • Visualizing the interfacial evolution from charge compensation to metallic screening across the manganite metal-insulator transition Reviewed

    Julia A. Mundy, Yasuyuki Hikita, Takeaki Hidaka, Takeaki Yajima, Takuya Higuchi, Harold Y. Hwang, David A. Muller, Lena F. Kourkoutis

    NATURE COMMUNICATIONS   5   2014.3

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    Electronic changes at polar interfaces between transition metal oxides offer the tantalizing possibility to stabilize novel ground states yet can also cause unintended reconstructions in devices. The nature of these interfacial reconstructions should be qualitatively different for metallic and insulating films as the electrostatic boundary conditions and compensation mechanisms are distinct. Here we directly quantify with atomic-resolution the charge distribution for manganite-titanate interfaces traversing the metal-insulator transition. By measuring the concentration and valence of the cations, we find an intrinsic interfacial electronic reconstruction in the insulating films. The total charge observed for the insulating manganite films quantitatively agrees with that needed to cancel the polar catastrophe. As the manganite becomes metallic with increased hole doping, the total charge build-up and its spatial range drop substantially. Direct quantification of the intrinsic charge transfer and spatial width should lay the framework for devices harnessing these unique electronic phases.

    DOI: 10.1038/ncomms4464

  • High electron mobility (16 cm2/Vsec) FETs with high on/off ratio (10^6) and highly conductive films (10^2 S/cm) by chemical doping in very thin (∼20 nm) TiO2 films on thermally grown SiO2 Reviewed

    Go Oike, Takeaki Yajima, Tomonori Nishimura, Kosuke Nagashio, Akira Toriumi

    Technical Digest - International Electron Devices Meeting, IEDM   2013.12

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    DOI: 10.1109/IEDM.2013.6724610

  • Atomically Flat Germanium (111) Surface by Hydrogen Annealing Reviewed

    T. Nishimura, S. Kabuyanagi, C. H. Lee, T. Yajima, K. Nagashio, A. Toriumi

    ULSI PROCESS INTEGRATION 8   58 ( 9 )   201 - 206   2013.10

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    In germanium (Ge) MOSFET technology, surface planarization is a serious concern for mobility enhancement at high carrier density, reliability improvement of gate dielectrics and morphology control for non-planar FETs. In this work, (111)-oriented Ge substrates were annealed at 350-750 degrees C in pure H-2 atmosphere, and the surface structure and morphology were analyzed with atomic force microscopy. A step and terrace structure was observed on the surface after the H-2 annealing above 500 degrees C. The terrace width is controllable by the off-angle of the initial surface within 0.3 degrees at least. The roughness root mean square (RMS) at 100 x 100 nm on single terrace is similar to 0.05 nm which is almost our detection limit, which implies that the single terrace on H-2 annealed Ge (111) is atomically flat. Furthermore, even though the initial surface roughness RMS is intentionally increased up to 0.6 nm, atomically flat terrace structure could be obtained by the H-2 annealing.

    DOI: 10.1149/05809.0201ecst

  • Coexistence of two-dimensional and three-dimensional Shubnikov–de Haas oscillations in Ar+-irradiated KTaO3 Reviewed

    S. Harashima, C. Bell, M. Kim, T. Yajima, Y. Hikita, H. Y. Hwang

    Phys. Rev. B   88 ( 8 )   085102   2013.8

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    Coexistence of two-dimensional and three-dimensional Shubnikov-de Haas oscillations in Ar+-irradiated KTaO3
    We report electron doping in the surface vicinity of KTaO3 by inducing oxygen vacancies via Ar+ irradiation. The doped electrons have high mobility (&gt
    104 cm2/Vs) at low temperatures, and exhibit Shubnikov-de Haas oscillations with both two- and three-dimensional components. A disparity of the extracted in-plane effective mass, compared to the bulk values, suggests mixing of the orbital characters. Our observations demonstrate that Ar+ irradiation serves as a flexible tool to study low-dimensional quantum transport in 5d semiconducting oxides. ©2013 American Physical Society.

    DOI: 10.1103/PhysRevB.88.085102

  • Hot electron transport in a strongly correlated transition-metal oxide Reviewed

    Kumari Gaurav Rana, Takeaki Yajima, Subir Parui, Alexander F. Kemper, Thomas P. Devereaux, Yasuyuki Hikita, Harold Y. Hwang, Tamalika Banerjee

    SCIENTIFIC REPORTS   3   2013.2

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    Oxide heterointerfaces are ideal for investigating strong correlation effects to electron transport, relevant for oxide-electronics. Using hot-electrons, we probe electron transport perpendicular to the La0.7Sr0.3MnO3 (LSMO)- Nb-doped SrTiO3 (Nb:STO) interface and find the characteristic hot-electron attenuation length in LSMO to be 1.48 +/- 0.10 unit cells (u.c.) at -1.9 V, increasing to 2.02 +/- 0.16 u.c. at -1.3 V at room temperature. Theoretical analysis of this energy dispersion reveals the dominance of electron-electron and polaron scattering. Direct visualization of the local electron transport shows different transmission at the terraces and at the step-edges.

    DOI: 10.1038/srep01274

  • ペロブスカイト酸化物における界面ダイポールの設計とトランジスタへの応用

    矢嶋赳彬

    先端技術大賞   2012.6

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    Language:Others  

    Design of interfacial dipole in perovskite oxides and its application to transistors

  • Reentrant insulating state in ultrathin manganite films Reviewed

    Bongju Kim, Daeyoung Kwon, Takeaki Yajima, Christopher Bell, Yasuyuki Hikita, Bog G. Kim, Harold Y. Hwang

    APPLIED PHYSICS LETTERS   99 ( 9 )   2011.8

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    Language:English   Publishing type:Research paper (scientific journal)  

    The transport and magnetic properties of La0.7Sr0.3MnO3 thin-films grown by pulsed laser deposition on (LaAlO3)(0.3)(SrAl0.5Ta0.5O3)(0.7) single crystal substrates have been investigated. A systematic series with various thicknesses of La0.7Sr0.3MnO3 was used to establish a phase diagram which showed a clear difference compared to films grown on SrTiO3 substrates, highlighting the importance of film thickness, and substrate strain. At 8 unit cells, the boundary between the metallic and insulating groundstates, a second abrupt metal-insulator transition was observed at low temperatures, which could be tuned by magnetic field, and was interpreted as a signature of electronic phase separation. (C) 2011 American Institute of Physics. [doi:10.1063/1.3628659]

    DOI: 10.1063/1.3628659

  • Charge Writing at the LaAlO3/SrTiO3 Surface Reviewed

    Yanwu Xie, Christopher Bell, Takeaki Yajima, Yasuyuki Hikita, Harold Y. Hwang

    NANO LETTERS   10 ( 7 )   2588 - 2591   2010.7

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    Language:English   Publishing type:Research paper (scientific journal)  

    Biased conducting-up atomic force microscopy (AFM) has been shown to write and erase nanoscale metallic lines at the LaAlO3/SrTiO3 interface Using various AFM modes, we show the mechanism of conductivity switching is the writing of surface charge These charges are stably deposited on a wide range of LaAlO3 thicknesses, including bulk crystals. A strong asymmetry with writing polarity was found for 1 and 2 unit cells of LaAlO3, providing experimental evidence for a theoretically predicted built-in potential

    DOI: 10.1021/nl1012695

  • Mn3O4 precipitates in laser-ablated manganite films Reviewed

    T. Higuchi, T. Yajima, L. Fitting Kourkoutis, Y. Hikita, N. Nakagawa, D. A. Muller, H. Y. Hwang

    APPLIED PHYSICS LETTERS   95 ( 4 )   043112   2009.7

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    Precipitates formed during the growth of manganite thin films by pulsed laser deposition have been an obstacle for fabricating high quality devices incorporating these ferromagnetic metals. In order to analyze the nature of these precipitates, we have investigated their spectroscopic and structural properties by scanning transmission electron microscopy. For LaMnO3 films, crystallites of Mn3O4 are found to segregate out from stoichiometric films to accommodate a net cation off-stoichiometry during growth. By tuning the laser spot conditions, these precipitates can be eliminated.

    DOI: 10.1063/1.3193667

  • Termination control of the interface dipole in La0.7Sr0.3MnO3/Nb:SrTiO3 (001) Schottky junctions Reviewed

    Yasuyuki Hikita, Mitsuru Nishikawa, Takeaki Yajima, Harold Y. Hwang

    PHYSICAL REVIEW B   79 ( 7 )   2009.2

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    In order to investigate the interface termination dependence of perovskite band alignments, we have studied the Schottky barrier height at La0.7Sr0.3MnO3/Nb:SrTiO3 (001) heterointerfaces. As the Nb:SrTiO3 semiconductor was varied from TiO2 termination to SrO termination by variable insertion of a SrMnO3 layer, a large systematic increase in the Schottky barrier height was observed. This can be ascribed to the evolution of the interface dipole induced to screen the polar discontinuity at the interface, which gives a large internal degree of freedom for tuning band diagrams in oxides.

    DOI: 10.1103/PhysRevB.79.073101

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Books

  • 環境発電ハンドブック 第2版

    矢嶋赳彬(Role:Joint author)

    エヌ・ティー・エス  2022.4 

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    Responsible for pages:p43-47   Language:Japanese   Book type:Scholarly book

  • 環境発電ハンドブック 第2版

    矢嶋赳彬

    エヌ・ティー・エス  2021.10 

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    Language:Others  

Presentations

  • 酸化物相転移とプロトンを駆使したニューロモルフィックデバイス設計 Invited

    矢嶋赳彬

    第258回JOEM研究会  2023.12 

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    Language:Others  

    Country:Other  

    Neuromorphic device design using oxide phase transition and protons

  • Smart energy extraction from energy harvesters using timing-based asynchronous digital circuits Invited

    Takeaki Yajima

    IEEE-NEMS2022  2022.4 

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    Language:Others  

    Country:Other  

  • Low-power circuits for energy harvesters based on spiking-neuron delay elements Invited

    Takeaki Yajima

    EuMW2021  2022.4 

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    Language:Others  

    Country:Other  

  • 持続可能社会のためのニューロモルフィックデバイス設計 Invited

    矢嶋赳彬

    学振R031ハイブリッド量子ナノ技術委員会 第7回研究会  2022.8 

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    Language:Others  

    Country:Other  

  • 環境発電の普及に向けた電源回路技術の動向について Invited

    矢嶋赳彬

    SDRJ委員会  2023.1 

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    Language:Others  

    Country:Other  

    Trends in Power Supply Circuit Technology for Widespread Use of Energy Harvesting

  • プロトンを用いたニューロモルフィック情報素子の設計 Invited

    矢嶋赳彬

    第70回応用物理学会春季学術講演会  2023.3 

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    Language:Others  

    Country:Other  

    Design of neuromorphic information devices using protons

  • Designing neuromorphic devices using protons Invited

    Takeaki Yajima

    IWDTF 2023 (2023, Kanazawa, Japan)  2023.10 

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    Country:Other  

    Designing neuromorphic devices using protons

  • スパイキングニューラルネットを用いたエッジAIと環境発電のへの応用 Invited

    矢嶋赳彬

    エネルギーハーベスティングコンソーシアム総会 (2023, Tokyo)  2023.6 

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    Language:Others  

    Country:Other  

    Edge AI using spiking neural networks and its application to energy harvesting

  • 固体プロトン素子を用いたニューロモルフィック機能設計 Invited

    矢嶋赳彬

    第85回固体イオニクス研究会 (2023, Tokyo)  2023.7 

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    Language:Others  

    Country:Other  

    Neuromorphic Functional Design Using Solid-State Proton Devices

  • 酸化物ヘテロ構造とプロトンを用いたニューロモルフィック素子 Invited

    矢嶋赳彬

    第84回応用物理学会秋季講演会 (2023, Kumamoto)  2023.9 

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    Country:Other  

    Neuromorphic Devices Using Oxide Heterostructures and Protons

  • プロトンを用いたニューロモルフィック情報処理 Invited

    矢嶋赳彬

    新材料・新原理で築く ニューロモルフィックシステム (2023, Osaka)  2023.8 

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    Country:Other  

    Neuromorphic information processing using proton

  • ニューロン回路と材料機能を用いた超低消費電力化技術の研究 Invited

    矢嶋赳彬

    Neumorphランチョンセミナー  2021.10 

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    Language:Others  

    Country:Other  

    Research on low power electronics based on neuron circuits and materials properties

  • Ultra-sharp three-terminal switch using nano-scale phase transition material Invited

    Takeaki Yajima

    34th International Microprocesses and Nanotechnology Conference (MNC 2021)  2021.10 

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    Language:Others  

    Country:Other  

  • 非同期デジタル制御による振動発電用回路 Invited

    矢嶋赳彬

    環境発電関連技術の最先端(応用物理学会エネルギーハーベスティング研究グループ)  2021.11 

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    Language:Others  

    Country:Other  

  • Codesign of materials and circuits for neuromorphic edge computing Invited

    Takeaki Yajima

    ナノ学会 合同シンポジウム  2021.12 

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    Language:Others  

    Country:Other  

    Codesign of materials and circuits for neuromorphic edge computing

  • Next-generation switching devices based on metal-insulator transitions Invited

    Takeaki Yajima

    ISPlasma2022  2022.3 

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    Language:Others  

    Country:Other  

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MISC

  • Energy-saving IoT technology learned from biological neural circuits Invited Reviewed

    Takeaki Yajima

    Applied Physics   93 ( 5 )   289 - 293   2024.5

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    Authorship:Lead author, Last author, Corresponding author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

    DOI: 10.11470/oubutsu.93.5_289

    researchmap

  • 神経回路のアナロジーに基づく省エネエレクトロニクス Reviewed

    矢嶋 赳彬

    電気学会誌   2024.2

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    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

    Energy-saving Electronics Based on the Analogy of Neural Circuits

    DOI: 10.1541/ieejjournal.144.84

  • スパイキングニューロン回路を用いた低消費電力IoT回路技術

    矢嶋赳彬

    機能材料   2021.3

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    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

  • 金属絶縁体転移材料を利用した回路技術の研究 Reviewed

    矢嶋 赳彬

    電子情報通信学会 和文論文誌C   2020.9

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    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

  • ペロブスカイト酸化物へテロ界面における界面ダイポールを用いたバンドオフセット制御

    矢嶋赳彬、疋田育之、簑原誠人、Christopher BELL、組頭広志、尾嶋正治、Julia A. MUNDY、Lena FITTING KOURKOUTIS、David. A. MULLER、Harold HWANG

    PF News   2012.4

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    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

  • Engineering Artificial Interface Dipoles at Oxide Heterointerfaces.

    T. Yajima, Y. Hikita, M. Minohara, C. Bell, J. A. Mundy, L. Fitting Kourkoutis, D. A. Muller, H. Kumigashira, M. Oshima, H. Y. Hwang

    PF Activity Report   2015.6

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    Language:Others  

    Engineering Artificial Interface Dipoles at Oxide Heterointerfaces.

  • Engineering Artificial Interface Dipoles at Oxide Heterointerfaces

    T. Yajima, Y. Hikita, M. Minohara, C. Bell, J. A. Mundy, L. Fitting Kourkoutis, D. A. Muller, H. Kumigashira, M. Oshima, and H. Y. Hwang

    PF Activity Report   2015.4

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    Language:English   Publishing type:Internal/External technical report, pre-print, etc.  

    Other Link: http://pfwww.kek.jp/acr/2014pdf/part_a/14ah1_2.pdf

  • ペロブスカイト酸化物における界面ダイポールの設計とトランジスタへの応用 Reviewed

    矢嶋赳彬

    独創性を拓く 先端技術大賞   2012.6

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    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

    Other Link: http://www.fbi-award.jp/sentan/jusyou/2012/3.pdf

  • Controlling Band Alignments by Engineering Interface Dipoles at Perovskite Oxide Heterointerfaces.

    T. Yajima, Y. Hikita, M. Minohara, C. Bell, H. Kumigashira, M. Oshima, J. A. Mumdy, L. F. Kourkoutis, D. A. Muller, H. Hwang

    PF News   2012.1

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    Language:Others  

    Controlling Band Alignments by Engineering Interface Dipoles at Perovskite Oxide Heterointerfaces.

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Industrial property rights

Patent   Number of applications: 14   Number of registrations: 1
Utility model   Number of applications: 0   Number of registrations: 0
Design   Number of applications: 0   Number of registrations: 0
Trademark   Number of applications: 0   Number of registrations: 0

Professional Memberships

  • IEEE

  • JSAP Silicon Technology Devision

  • JAPANESE NEURAL NETWORK SOCIETY

  • Material Research Society

  • THE JAPAN SOCIETY OF APPLIED PHYSICS

Committee Memberships

  • International Conference on Solid State Devices and Materials (SSDM)   Organizer   Foreign country

    2024.1 - 2025.9   

  • 応用物理学会 中分類(酸化物エレクトロニクス)   プログラム委員   Domestic

    2023.4 - 2025.3   

  • ニューロモルフィックAIハードウェア研究センター   外部委員   Domestic

    2021.7 - Present   

  • Silicon Nanotechnology Workshop   プログラム委員   Foreign country

    2020.10 - 2023.3   

  • The System Device Roadmap Committee of Japan (SDRJ), More than Moore working group (MtM)   Organizer   Domestic

    2019.12 - Present   

  • 応用物理学会 トータルバイオミメティクス領域グループ   Organizer   Domestic

    2019.11 - 2023.4   

  • エネルギーハーベスティングコンソーシアム   正式オブザーバ   Domestic

    2018.4 - Present   

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Academic Activities

  • オーガナイザ

    脳機能から考えるレザバーコンピューティングの未来  ( Japan ) 2021.8

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    Type:Competition, symposium, etc. 

    Number of participants:55

  • オーガナイザ

    バイオミメティック情報処理の最前線  ( Japan ) 2020.11

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    Type:Competition, symposium, etc. 

  • Executive Comittee International contribution

    2018 International Conference on Solid State Devices and Materials  ( Tokyo Japan ) 2018.9

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    Type:Competition, symposium, etc. 

  • 代表企画者

    第23回 電子デバイス界面テクノロジー研究会 企画セッション「ポストディープラーニングに向けたニューロチップの基盤技術」  ( Japan ) 2018.1

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    Type:Competition, symposium, etc. 

  • 代表世話人

    春季応用物理学会 シンポジウム「次世代ニューロモルフィックハードウェアにおける機能性酸化物の役割」  ( Japan ) 2017.3

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    Type:Competition, symposium, etc. 

Research Projects

  • 自立センサノードのためのバイオミメティック汎用電源回路

    2022 - 2027

    Industrial Technology Research Grant Program (Ministry of Economy, Trade and Industry)

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    Authorship:Principal investigator  Grant type:Contract research

  • スパイキングネットによるエッジでのリアルタイム学習基盤

    2019 - 2024

    JST Strategic Basic Research Program (Ministry of Education, Culture, Sports, Science and Technology)

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    Authorship:Coinvestigator(s)  Grant type:Contract research

  • 抵抗変化素子を活用した環境発電用回路技術の創成

    2017 - 2020

    JST Strategic Basic Research Program (Ministry of Education, Culture, Sports, Science and Technology)

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    Authorship:Principal investigator  Grant type:Contract research

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.

Class subject

  • 電磁気学基礎

    2023.12 - 2024.2   Winter quarter

  • 電気電子工学読解Ⅱ

    2023.10 - 2024.3   Second semester

  • 電気電子工学演示Ⅱ

    2023.10 - 2024.3   Second semester

  • 電磁気学基礎

    2023.10 - 2023.12   Fall quarter

  • 電気工学基礎Ⅱ

    2023.6 - 2023.8   Summer quarter

  • Neuromorphic Hardware II

    2023.6 - 2023.8   Summer quarter

  • ニューロコンピューティング特論Ⅱ

    2023.6 - 2023.8   Summer quarter

  • ニューロモルフィックハードウェア特論Ⅱ

    2023.6 - 2023.8   Summer quarter

  • 構成エレクトロニクス特別講究

    2023.4 - 2024.3   Full year

  • Advanced Research in Electrical and Electronic Eng II

    2023.4 - 2024.3   Full year

  • Advanced Research in Electrical and Electronic Engineering I

    2023.4 - 2024.3   Full year

  • Advanced Seminar in Electrical and Electronic Engineering

    2023.4 - 2024.3   Full year

  • 電気電子工学特別研究Ⅱ

    2023.4 - 2024.3   Full year

  • 電気電子工学特別研究Ⅰ

    2023.4 - 2024.3   Full year

  • 電気電子工学特別演習

    2023.4 - 2024.3   Full year

  • Advanced Research in Constructive Electronics

    2023.4 - 2024.3   Full year

  • 電気工学基礎

    2023.4 - 2023.9   First semester

  • 電気電子工学演示Ⅰ

    2023.4 - 2023.9   First semester

  • 電気電子工学読解Ⅰ

    2023.4 - 2023.9   First semester

  • 電気工学基礎Ⅰ

    2023.4 - 2023.6   Spring quarter

  • ニューロコンピューティング特論Ⅰ

    2023.4 - 2023.6   Spring quarter

  • 量子力学応用Ⅰ

    2023.4 - 2023.6   Spring quarter

  • 量子力学応用Ⅰ

    2023.4 - 2023.6   Spring quarter

  • 電磁気学基礎

    2022.12 - 2023.2   Winter quarter

  • 電磁気学基礎

    2022.10 - 2022.12   Fall quarter

  • ニューロモルフィックハードウェア特論Ⅱ

    2022.6 - 2022.8   Summer quarter

  • Neuromorphic Hardware II

    2022.6 - 2022.8   Summer quarter

  • 電気電子工学企画演習

    2022.4 - 2022.9   First semester

  • 工学概論(Ⅰ群)

    2022.4 - 2022.9   First semester

  • 量子力学大意

    2022.4 - 2022.9   First semester

  • 電気電子工学特別研究第ニ 1G

    2022.4 - 2022.9   First semester

  • 電気電子工学読解Ⅰ

    2022.4 - 2022.9   First semester

  • 電気電子工学演示Ⅰ

    2022.4 - 2022.9   First semester

  • 電気電子工学研究演示(第1グループ)

    2022.4 - 2022.9   First semester

  • Group Research Proposal for EEE

    2022.4 - 2022.9   First semester

  • Survey in EEE Studies(Group1)

    2022.4 - 2022.9   First semester

  • ニューロモルフィックハードウェア特論Ⅰ

    2022.4 - 2022.6   Spring quarter

  • Neuromorphic Hardware I

    2022.4 - 2022.6   Spring quarter

  • 量子力学応用Ⅰ

    2022.4 - 2022.6   Spring quarter

  • 電磁気学基礎

    2021.12 - 2022.2   Winter quarter

  • 電磁気学基礎

    2021.10 - 2022.3   Second semester

  • 電気電子工学読解Ⅱ

    2021.10 - 2022.3   Second semester

  • 電気電子工学研究調査(第1グループ)

    2021.10 - 2022.3   Second semester

  • 電磁気学基礎

    2021.10 - 2021.12   Fall quarter

  • ニューロモルフィックハードウェア特論Ⅱ

    2021.6 - 2021.8   Summer quarter

  • Neuromorphic Hardware II

    2021.6 - 2021.8   Summer quarter

  • ニューロモルフィックハードウェア特論

    2021.4 - 2021.9   First semester

  • 電気電子工学読解Ⅰ

    2021.4 - 2021.9   First semester

  • [M2]電気電子工学演習第三

    2021.4 - 2021.9   First semester

  • 量子力学応用1

    2021.4 - 2021.6   Spring quarter

  • Neuromorphic Hardware I

    2021.4 - 2021.6   Spring quarter

  • 量子力学応用Ⅰ

    2021.4 - 2021.6   Spring quarter

  • ニューロモルフィックハードウェア特論Ⅰ

    2021.4 - 2021.6   Spring quarter

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FD Participation

  • 2022.1   Role:Participation   Title:【シス情FD】シス情関連の科学技術に対する国の政策動向(に関する私見)

    Organizer:[Undergraduate school/graduate school/graduate faculty]

  • 2021.4   Role:Participation   Title:令和3年度 第1回全学FD(新任教員の研修)

    Organizer:University-wide

  • 2021.3   Role:Participation   Title:学習支援システム(M2B)講習会(オンライン開催)◇初級編・中・上級編◇13:00~15:00

    Organizer:University-wide

  • 2020.12   Role:Participation   Title:Moodle&MS Teams連携によるオンライン講義実施報告(Youtube Prezi Powerpoint Wolframcloud そして TeX)

    Organizer:[Undergraduate school/graduate school/graduate faculty]

Other educational activity and Special note

  • 2023  Class Teacher  学部

  • 2022  Class Teacher  学部

  • 2021  Class Teacher  学部

Media Coverage

  • 九大、生物の神経回路に学ぶ超省エネIoT制御技術を確立 Newspaper, magazine

    日本経済新聞  2022.1

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    九大、生物の神経回路に学ぶ超省エネIoT制御技術を確立

Activities contributing to policy formation, academic promotion, etc.

  • 2023.3   応用物理学会シンポジウム「脳と非生体型自律分散システムにおける情報処理・創造の最前線」

    世話人

  • 2021.4 - 2021.8   第2回トータルバイオミメティクス研究会「脳機能から考えるレザバーコンピューティングの未来」

    代表企画者

  • 2020.5 - 2022.3   応用物理学会 若手チャプタ

    副代表

  • 2018.11 - 2019.3   International Workshop on Materials Science & Device Physics for Advanced Electron Devices

    実行委員

  • 2017.10 - 2018.9   SSDM 2018

    実行委員

  • 2017.6 - 2018.1   第23回 電子デバイス界面テクノロジー研究会 企画セッション"ポストディープラーニングに向けたニューロチップの基盤技術"

    代表企画者

  • 2016.9 - 2017.3   春季応用物理学会 2017 シンポジウム "次世代ニューロモルフィックハードウェアにおける機能性酸化物の役割"

    代表世話人

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