Updated on 2026/04/28

写真a

 
IWASAKI TAKAYUKI
 
Organization
School of Engineering Professor
Title
Professor
External link

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News & Media

Research Areas

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Electric and electronic materials

  • Nanotechnology/Materials / Nanostructural physics

Research History

  • Institute of Science Tokyo   Professor

    2024.10

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  • Tokyo Institute of Technology   Professor

    2024.7 - 2024.9

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  • Tokyo Institute of Technology   School of Engineering   Associate Professor

    2018.4 - 2024.6

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  • さきがけ研究員（兼務）   「光の極限制御・積極利用と新分野開拓」

    2016.10 - 2020.3

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  • Tokyo Institute of Technology   School of Engineering   Assistant Professor

    2016.4 - 2018.3

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  • Tokyo Institute of Technology   Graduate School of Science and Engineering   Assistant Professor

    2011.4 - 2016.3

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  • マックスプランク固体物理学研究所   日本学術振興会 海外特別研究員

    2010.2 - 2011.3

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    Country：Germany

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  • マックスプランク固体物理学研究所   ドイツ・フンボルト財団研究員

    2008.12 - 2010.1

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    Country：Germany

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  • ドイツ・フンボルト財団研究員（ゲーテ・インスティトゥート語学研修）

    2008.10 - 2008.11

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    Country：Germany

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  • Waseda University Faculty of Science and Engineering

    2007.4 - 2008.9

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Papers

  • Performance evaluation of a diamond quantum magnetometer for biomagnetic sensing: A phantom study

    Naota Sekiguchi, Yuta Kainuma, Motofumi Fushimi, Chikara Shinei, Masashi Miyakawa, Takashi Taniguchi, Tokuyuki Teraji, Hiroshi Abe, Shinobu Onoda, Takeshi Ohshima, Mutsuko Hatano, Masaki Sekino, Takayuki Iwasaki

    Applied Physics Letters   126 ( 19 )   2025.5

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    Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

    We employ a dry-type phantom to evaluate the performance of a diamond quantum magnetometer with a high sensitivity of about 6 pT/Hz from the viewpoint of practical measurement in biomagnetic sensing. The dry phantom is supposed to represent an equivalent current dipole (ECD) generated by brain activity, emulating an encephalomagnetic field. The spatial resolution of the magnetometer is evaluated to be sufficiently higher than the length of the variation in the encephalomagnetic field distribution. The minimum detectable ECD moment is evaluated to be 0.2 nA m by averaging about 8000 measurements for a standoff distance of 2.4 mm from the ECD. We also discuss the feasibility of detecting an ECD in the measurement of an encephalomagnetic field in humans. We conclude that it is feasible to detect an encephalomagnetic field from a shallow cortex area such as the primary somatosensory cortex.

    DOI： 10.1063/5.0254828

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  • Compact and Stable Diamond Quantum Sensors for Wide Applications

    Yuta Kainuma, Yuji Hatano, Takayuki Shibata, Naota Sekiguchi, Akimichi Nakazono, Hiromitsu Kato, Shinobu Onoda, Takeshi Ohshima, Mutsuko Hatano, Takayuki Iwasaki

    Advanced Quantum Technologies   2024.6

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    Publishing type：Research paper (scientific journal)   Publisher：Wiley  

    Abstract

    This study proposes compact, highly sensitive, and stable diamond quantum sensors for a wide range of applications, including biomedical and energy electronics. For enhanced sensitivity and alignment precision within the objective field, a high‐quality, (111)‐oriented 12C‐enriched chemical vapor deposition (CVD) diamond, featuring a nitrogen‐vacancy (NV) axis in the (111) direction, is employed as the sensor. To increase the fluorescence collection efficiency, the laser beam is irradiated from the side surface of the CVD diamond, and fluorescence is detected using a compound parabolic concentrator (CPC) lens. The floor noise level of the magnetic field signal is 44 pT/Hz0.5. An Allan deviation of 1.2 pT over 1000 s of averaging demonstrates stability. This is attributable to the integration of a balancing circuit to cancel out laser noise, alongside mechanisms to compensate for temperature fluctuations and a copper housing to shield against electromagnetic field noise.

    DOI： 10.1002/qute.202300456

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  • Diamond quantum magnetometer with dc sensitivity of sub-10 pT <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>Hz</mml:mi><mml:msup><mml:mspace width="0.2em"/><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:math> toward measurement of biomagnetic field

    N. Sekiguchi, M. Fushimi, A. Yoshimura, C. Shinei, M. Miyakawa, T. Taniguchi, T. Teraji, H. Abe, S. Onoda, T. Ohshima, M. Hatano, M. Sekino, T. Iwasaki

    Physical Review Applied   21 ( 6 )   2024.6

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    Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

    DOI： 10.1103/physrevapplied.21.064010

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    Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevApplied.21.064010/fulltext

  • Fast coherent control of nitrogen-14 spins associated with nitrogen-vacancy centers in diamonds using dynamical decoupling

    Kosuke Mizuno, Ikuya Fujisaki, Hiroyoshi Tomioka, Hitoshi Ishiwata, Shinobu Onoda, Takayuki Iwasaki, Keigo Arai, Mutsuko Hatano

    Journal of Physics Communications   8 ( 3 )   035002 - 035002   2024.3

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    Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

    Abstract

    A nitrogen-vacancy (NV) center in a diamond enables the access to an electron spin, which is expected to present highly sensitive quantum sensors. Although exploiting a nitrogen nuclear spin improves the sensitivity, manipulating it using a resonant pulse requires a long gate time owing to its small gyromagnetic ratio. Another technique to control nuclear spins is a conditional rotation gate based on dynamical decoupling, which is faster but unavailable for nitrogen spins owing to the lack of transverse hyperfine coupling with the electron spin. In this study, we generated effective transverse coupling by applying a weak off-axis magnetic field. An effective coupling depends on the off-axis field; the conditional rotation gate on the nitrogen-14 spins of an NV center was demonstrated within 4.2 μs under an 1.8% off-axis field and a longitudinal field of approximately 280 mT. We estimated that a population transfer from the electron to nitrogen spins can be implemented with 8.7 μs. Our method is applicable to an ensemble of NV centers, in addition to a single NV center.

    DOI： 10.1088/2399-6528/ad2b8b

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    Other Link： https://iopscience.iop.org/article/10.1088/2399-6528/ad2b8b/pdf

  • Wide-field imaging of the magnetization process in soft magnetic-thin film using diamond quantum sensors Reviewed

    Ryota Kitagawa, Teruo Kohashi, Takeyuki Tsuji, Shunsuke Nagata, Aoi Nakatsuka, Honami Nitta, Yota Takamura, Shigeki Nakagawa, Takayuki Iwasaki, Mutsuko Hatano

    Applied Physics Express   17 ( 1 )   017002/1 - 5   2023.12

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

    Abstract

    The magnetization process of a soft magnetic CoFeB-SiO2 thin film was imaged using diamond quantum sensors with perfectly aligned nitrogen-vacancy centers along the [111] direction formed by CVD. Around the film edge, the easy and hard axes directions exhibited different responses to the external magnetic field, consistent with ones observed by magneto-optical Kerr effect microscopy. Moreover, quantum diamond imaging could observe discontinuous magnetization along domain walls as non-uniform magnetic charges (MCs). Quantum diamond imaging would help in visualization through MCs, such as irregularity in the material and relative orientation of magnetizations in neighboring domains.

    DOI： 10.35848/1882-0786/ad1002

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    Other Link： https://iopscience.iop.org/article/10.35848/1882-0786/ad1002/pdf

  • Wide-field quantitative magnetic imaging of superconducting vortices using perfectly aligned quantum sensors

    Shunsuke Nishimura, Taku Kobayashi, Daichi Sasaki, Takeyuki Tsuji, Takayuki Iwasaki, Mutsuko Hatano, Kento Sasaki, Kensuke Kobayashi

    Applied Physics Letters   123 ( 11 )   2023.9

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    Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

    Various techniques have been applied to visualize superconducting vortices, providing clues to their electromagnetic response. Here, we present a wide-field, quantitative imaging of the stray field of the vortices in a superconducting thin film using perfectly aligned diamond quantum sensors. Our analysis, which mitigates the influence of the sensor inhomogeneities, visualizes the magnetic flux of single vortices in YBa2Cu3O7−δ with an accuracy of ±10%. The obtained vortex shape is consistent with the theoretical model, and penetration depth and its temperature dependence agree with previous studies, proving our technique's accuracy and broad applicability. This wide-field imaging, which in principle works even under extreme conditions, allows the characterization of various superconductors.

    DOI： 10.1063/5.0169521

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  • Pressure Sensor Using a Hybrid Structure of a Magnetostrictive Layer and Nitrogen-Vacancy Centers in Diamond Reviewed

    Ryota Kitagawa, Shunsuke Nagata, Keigo Arai, Kosuke Mizuno, Takeyuki Tsuji, Ikuya Fujisaki, Soki Urashita, Teruo Kohashi, Yota Takamura, Takayuki Iwasaki, Shigeki Nakagawa, Mutsuko Hatano

    Physical Review Applied   19 ( 4 )   044089/1 - 10   2023.4

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

    DOI： 10.1103/physrevapplied.19.044089

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    Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevApplied.19.044089/fulltext

  • Electroluminescence of negatively charged single NV centers in diamond

    M. Haruyama, H. Kato, M. Ogura, Y. Kato, D. Takeuchi, S. Yamasaki, T. Iwasaki, H. Morishita, M. Fujiwara, N. Mizuochi, T. Makino

    Applied Physics Letters   122 ( 7 )   072101 - 072101   2023.2

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    Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

    The realization of electroluminescence (EL) of negatively charged nitrogen vacancy (NV−) centers is important toward all-electrical control of diamond quantum devices. In this study, we demonstrated electrical excitation and detection of EL of single NV− centers by using lateral diamond p+–i(n−)–n+ diodes. It had been grown by homoepitaxy using the plasma enhanced chemical vapor deposition technique. We introduced a lightly phosphorus doped i(n−) layer to stabilize the negative state of NV centers. It was estimated that the efficiency of the electrical excitation rate of the NV center was more than 30 times enhanced by introducing lateral diamond p+–i(n−)–n+ diodes structure compared with the previous vertical diode. Furthermore, the EL of a single NV− center embedded in the i(n−) layer region was characterized. The results show that the charge state of the single NV centers can be manipulated by the voltage applied to the p+–i(n−)–n+ diode, where the emission of EL is increasingly dominated by NV− in the range of 30 to 50 V.

    DOI： 10.1063/5.0138050

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  • Transfer-printing-based integration of silicon nitride grating structure on single-crystal diamond toward sensitive magnetometers

    Ryota Katsumi, Takeshi Hizawa, Akihiro Kuwahata, Shun Naruse, Yuji Hatano, Takayuki Iwasaki, Mutsuko Hatano, Fedor Jelezko, Shinobu Onoda, Takeshi Ohshima, Masaki Sekino, Takashi Yatsui

    Applied Physics Letters   121 ( 16 )   161103 - 161103   2022.10

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    Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

    Negatively charged nitrogen-vacancy (NV) centers in diamond have emerged as promising candidates for a wide range of quantum applications, especially quantum sensing of magnetic field. Implementation of nanostructure into diamond is powerful for efficient photon collection of NV centers and chip-scale miniaturization of the device, which is crucial for sensitive and practical diamond magnetometers. However, fabrication of the diamond nanostructure involves technical limitations and can degrade the spin coherence of the NV centers. In this study, we demonstrate the hybrid integration of a silicon nitride grating structure on a single-crystal diamond by utilizing transfer printing. This approach allows the implementation of the nanostructure in diamond using a simple pick-and-place assembly, facilitating diamond-based quantum applications without any complicated diamond nanofabrication. We observed the intensity enhancement in the collected NV emissions both theoretically and experimentally using the integrated grating structure. By applying the increased photon intensity, we demonstrate the improved magnetic sensitivity of the fabricated device. The proposed hybrid integration approach will offer a promising route toward a compact and sensitive diamond NV-based magnetometer.

    DOI： 10.1063/5.0107854

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  • Millimetre-scale magnetocardiography of living rats with thoracotomy

    Keigo Arai, Akihiro Kuwahata, Daisuke Nishitani, Ikuya Fujisaki, Ryoma Matsuki, Yuki Nishio, Zonghao Xin, Xinyu Cao, Yuji Hatano, Shinobu Onoda, Chikara Shinei, Masashi Miyakawa, Takashi Taniguchi, Masatoshi Yamazaki, Tokuyuki Teraji, Takeshi Ohshima, Mutsuko Hatano, Masaki Sekino, Takayuki Iwasaki

    Communications Physics   5 ( 1 )   2022.8

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    Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

    Abstract

    Magnetocardiography is a contactless imaging modality for electric current propagation in the cardiovascular system. Although conventional sensors provide sufficiently high sensitivity, their spatial resolution is limited to a centimetre-scale, which is inadequate for revealing the intra-cardiac electrodynamics such as rotational waves associated with ventricular arrhythmias. Here, we demonstrate invasive magnetocardiography of living rats at a millimetre-scale using a quantum sensor based on nitrogen-vacancy centres in diamond. The acquired magnetic images indicate that the cardiac signal source is well explained by vertically distributed current dipoles, pointing from the right atrium base via the Purkinje fibre bundle to the left ventricular apex. We also find that this observation is consistent with and complementary to an alternative picture of electric current density distribution calculated with a stream function method. Our technique will enable the study of the origin and progression of various cardiac arrhythmias, including flutter, fibrillation, and tachycardia.

    DOI： 10.1038/s42005-022-00978-0

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    Other Link： https://www.nature.com/articles/s42005-022-00978-0

  • High growth rate synthesis of diamond film containing perfectly aligned nitrogen-vacancy centers by high-power density plasma CVD

    Takeyuki Tsuji, Hitoshi Ishiwata, Takeharu Sekiguchi, Takayuki Iwasaki, Mutsuko Hatano

    Diamond and Related Materials   123   108840 - 108840   2022.3

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    Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

    DOI： 10.1016/j.diamond.2022.108840

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  • Vector magnetometry using perfectly aligned nitrogen-vacancy center ensemble in diamond Reviewed

    Moeta Tsukamoto, Kensuke Ogawa, Hayato Ozawa, Takayuki Iwasaki, Mutsuko Hatano, Kento Sasaki, Kensuke Kobayashi

    Applied Physics Letters   118 ( 26 )   264002 - 264002   2021.6

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    Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

    DOI： 10.1063/5.0054809

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  • Photoelectrical detection of nitrogen-vacancy centers by utilizing diamond lateral p–i–n diodes Reviewed

    T. Murooka, M. Shiigai, Y. Hironaka, T. Tsuji, B. Yang, T. M. Hoang, K. Suda, K. Mizuno, H. Kato, T. Makino, M. Ogura, S. Yamasaki, M. Hatano, T. Iwasaki

    Applied Physics Letters   118 ( 25 )   253502 - 253502   2021.6

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    Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

    DOI： 10.1063/5.0055852

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  • Gradiometer Using Separated Diamond Quantum Magnetometers Reviewed

    Yuta Masuyama, Katsumi Suzuki, Akira Hekizono, Mitsuyasu Iwanami, Mutsuko Hatano, Takayuki Iwasaki, Takeshi Ohshima

    Sensors   21 ( 3 )   977 - 977   2021.2

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    Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

    The negatively charged nitrogen-vacancy (NV) center in diamonds is known as the spin defect and using its electron spin, magnetometry can be realized even at room temperature with extremely high sensitivity as well as a high dynamic range. However, a magnetically shielded enclosure is usually required to sense weak magnetic fields because environmental magnetic field noises can disturb high sensitivity measurements. Here, we fabricated a gradiometer with variable sensor length that works at room temperature using a pair of diamond samples containing negatively charged NV centers. Each diamond is attached to an optical fiber to enable free sensor placement. Without any magnetically shielding, our gradiometer realizes a magnetic noise spectrum comparable to that of a three-layer magnetically shielded enclosure, reducing the noises at the low-frequency range below 1 Hz as well as at the frequency of 50 Hz (power line frequency) and its harmonics. These results indicate the potential of highly sensitive magnetic sensing by the gradiometer using the NV center for applications in noisy environments such as outdoor and in vehicles.

    DOI： 10.3390/s21030977

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  • Label‐Free Phase Change Detection of Lipid Bilayers Using Nanoscale Diamond Magnetometry Reviewed

    Hitoshi Ishiwata, Hiroshi C. Watanabe, Shinya Hanashima, Takayuki Iwasaki, Mutsuko Hatano

    Advanced Quantum Technologies   4 ( 4 )   2000106 - 2000106   2021.2

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    Publishing type：Research paper (scientific journal)   Publisher：Wiley  

    DOI： 10.1002/qute.202000106

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    Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qute.202000106

  • Magnetic Field Generation System of the Magnetic Probe With Diamond Quantum Sensor and Ferromagnetic Materials for the Detection of Sentinel Lymph Nodes With Magnetic Nanoparticles

    Takahiro Kitaizumi, Akihiro Kuwahata, Kota Saichi, Takumi Sato, Ryuji Igarashi, Takeshi Ohshima, Yuta Masuyama, Takayuki Iwasaki, Mutsuko Hatano, Fedor Jelezko, Moriaki Kusakabe, Takashi Yatsui, Masaki Sekino

    IEEE TRANSACTIONS ON MAGNETICS   57 ( 2 )   2021.2

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

    DOI： 10.1109/TMAG.2020.3009334

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  • Electron spin contrast of high-density and perfectly aligned nitrogen-vacancy centers synthesized by chemical vapor deposition Reviewed

    Kosuke Mizuno, Makoto Nakajima, Hitoshi Ishiwata, Mutsuko Hatano, Takayuki Iwasaki

    Applied Physics Express   14 ( 3 )   032001 - 032001   2021.1

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    Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

    DOI： 10.35848/1882-0786/abd868

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    Other Link： https://iopscience.iop.org/article/10.35848/1882-0786/abd868/pdf

  • Thermometric quantum sensor using excited state of silicon vacancy centers in 4H-SiC devices Reviewed

    Tuan Minh Hoang, Hitoshi Ishiwata, Yuta Masuyama, Yuichi Yamazaki, Kazutoshi Kojima, Sang-Yun Lee, Takeshi Ohshima, Takayuki Iwasaki, Digh Hisamoto, Mutsuko Hatano

    Applied Physics Letters   118 ( 4 )   044001 - 044001   2021.1

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    Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

    DOI： 10.1063/5.0027603

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  • Simultaneous thermometry and magnetometry using a fiber-coupled quantum diamond sensor Reviewed

    Yuji Hatano, Jaewon Shin, Daisuke Nishitani, Haruki Iwatsuka, Yuta Masuyama, Hiroki Sugiyama, Makoto Ishii, Shinobu Onoda, Takeshi Ohshima, Keigo Arai, Takayuki Iwasaki, Mutsuko Hatano

    Applied Physics Letters   118 ( 3 )   034001 - 034001   2021.1

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    Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

    DOI： 10.1063/5.0031502

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  • Vector Electrometry in a Wide-Gap-Semiconductor Device Using a Spin-Ensemble Quantum Sensor Reviewed

    Bang Yang, Takuya Murooka, Kosuke Mizuno, Kwangsoo Kim, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Satoshi Yamasaki, Marek E. Schmidt, Hiroshi Mizuta, Amir Yacoby, Mutsuko Hatano, Takayuki Iwasaki

    Physical Review Applied   14 ( 4 )   044049   2020.10

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    Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

    DOI： 10.1103/physrevapplied.14.044049

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    Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevApplied.14.044049/fulltext

  • Simultaneous wide-field imaging of phase and magnitude of AC magnetic signal using diamond quantum magnetometry Reviewed

    Kosuke Mizuno, Hitoshi Ishiwata, Yuta Masuyama, Takayuki Iwasaki, Mutsuko Hatano

    Scientific Reports   10 ( 1 )   11611   2020.7

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    Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

    <title>Abstract</title>Spectroscopic analysis of AC magnetic signal using diamond quantum magnetometry is a promising technique for inductive imaging. Conventional dynamic decoupling like XY8 provides a high sensitivity of an oscillating magnetic signal with intricate dependence on magnitude and phase, complicating high throughput detection of each parameter. In this study, a simple measurement scheme for independent and simultaneous detection of magnitude and phase is demonstrated by a sequential measurement protocol. Wide-field imaging experiment was performed for an oscillating magnetic field with approximately <inline-formula><alternatives><tex-math>$$100\,\upmu \hbox {m}$$</tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>100</mml:mn><mml:mspace /><mml:mi>μ</mml:mi><mml:mtext>m</mml:mtext></mml:mrow></mml:math></alternatives></inline-formula>-squared observation area. Single pixel phase precision was <inline-formula><alternatives><tex-math>$$2.1^{\circ }$$</tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>2</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>1</mml:mn><mml:mo>∘</mml:mo></mml:msup></mml:mrow></mml:math></alternatives></inline-formula> for <inline-formula><alternatives><tex-math>$$0.76\,\upmu \hbox {T}$$</tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.76</mml:mn><mml:mspace /><mml:mi>μ</mml:mi><mml:mtext>T</mml:mtext></mml:mrow></mml:math></alternatives></inline-formula> AC magnetic signal. Our method enables potential applications including inductive inspection and impedance imaging.

    DOI： 10.1038/s41598-020-68404-5

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    Other Link： http://www.nature.com/articles/s41598-020-68404-5

  • A quantum thermometric sensing and analysis system using fluorescent nanodiamonds for the evaluation of living stem cell functions according to intracellular temperature Reviewed

    Hiroshi Yukawa, Masazumi Fujiwara, Kaori Kobayashi, Yuka Kumon, Kazu Miyaji, Yushi Nishimura, Keisuke Oshimi, Yumi Umehara, Yoshio Teki, Takayuki Iwasaki, Mutsuko Hatano, Hideki Hashimoto, Yoshinobu Baba

    Nanoscale Advances   2 ( 5 )   1859 - 1868   2020.4

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

    DOI： 10.1039/d0na00146e

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  • Fabrication of and Investigation on Grating coupler for the Improvement of Light Extraction Efficiency of Magnetometer with Nitrogen-Vacancy Center in Diamond

    Sato Takumi, Kitaizumi Takahiro, Saichi Kota, Kuwahata Akihiro, Igarashi Ryuji, Ohshima Takeshi, Masuyama Yuta, Iwasaki Takayuki, Hating Mutsuko, Making Toshiharu, Yamasaki Satoshi, Jelezko Fedor, Kusakabe Moriaki, Sekino Masaki, Yatsui Takashi

    JSAP Annual Meetings Extended Abstracts   2020.1   723 - 723   2020.2

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    Language：Japanese   Publisher：The Japan Society of Applied Physics  

    DOI： 10.11470/jsapmeeting.2020.1.0_723

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  • Magnetometer with nitrogen-vacancy center in a bulk diamond for detecting magnetic nanoparticles in biomedical applications Reviewed

    Akihiro Kuwahata, Takahiro Kitaizumi, Kota Saichi, Takumi Sato, Ryuji Igarashi, Takeshi Ohshima, Yuta Masuyama, Takayuki Iwasaki, Mutsuko Hatano, Fedor Jelezko, Moriaki Kusakabe, Takashi Yatsui, Masaki Sekino

    Scientific Reports   10   2483   2020.2

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    Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

    <title>Abstract</title>We developed a novel magnetometer that employs negatively charged nitrogen-vacancy (NV−) centers in diamond, to detect the magnetic field generated by magnetic nanoparticles (MNPs) for biomedical applications. The compact probe system is integrated into a fiber-optics platform allowing for a compact design. To detect signals from the MNPs effectively, we demonstrated, for the first time, the application of an alternating current (AC) magnetic field generated by the excitation coil of several hundred microteslas for the magnetization of MNPs in diamond quantum sensing. In the lock-in detection system, the minimum detectable AC magnetic field (at a frequency of 1.025 kHz) was approximately 57.6 nT for one second measurement time. We were able to detect the micromolar concentration of MNPs at distances of a few millimeters. These results indicate that the magnetometer with the NV− centers can detect the tiny amounts of MNPs, thereby offering potential for future biomedical applications.

    DOI： 10.1038/s41598-020-59064-6

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    Other Link： http://www.nature.com/articles/s41598-020-59064-6

  • Spectroscopic investigations of negatively charged tin-vacancy centres in diamond Reviewed

    Johannes Görlitz, Dennis Herrmann, Gergő Thiering, Philipp Fuchs, Morgane Gandil, Takayuki Iwasaki, Takashi Taniguchi, Michael Kieschnick, Jan Meijer, Mutsuko Hatano, Adam Gali, Christoph Becher

    New Journal of Physics   22 ( 1 )   013048 - 013048   2020.1

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    Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

    DOI： 10.1088/1367-2630/ab6631

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    Other Link： https://iopscience.iop.org/article/10.1088/1367-2630/ab6631/pdf

  • Color centers based on heavy group-IV elements

    Takayuki Iwasaki

    Diamond for Quantum Applications Part 1   103   237 - 256   2020

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    Authorship：Lead author,　Corresponding author   Publishing type：Part of collection (book)   Publisher：Elsevier  

    DOI： 10.1016/bs.semsem.2020.03.007

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  • Characterization of Schottky Barrier Diodes on Heteroepitaxial Diamond on 3C-SiC/Si Substrates Reviewed

    Takuya Murooka, Mutsuko Hatano, Junya Yaita, Toshiharu Makino, Masahiko Ogura, Hiromitsu Kato, Satoshi Yamasaki, Meralys Natal, Stephen E. Saddow, Takayuki Iwasaki, Mutsuko Hatano

    IEEE Transactions on Electron Devices   67 ( 1 )   212 - 216   2019.12

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    Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

    DOI： 10.1109/ted.2019.2952910

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  • Formation of perfectly aligned high-density NV centers in (111) CVD-grown diamonds for magnetic field imaging of magnetic particles Reviewed

    Hayato Ozawa, Yuji Hatano, Takayuki Iwasaki, Yoshie Harada, Mutsuko Hatano

    Japanese Journal of Applied Physics   58 ( SI )   SIIB26 - SIIB26   2019.7

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    Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

    DOI： 10.7567/1347-4065/ab203c

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    Other Link： https://iopscience.iop.org/article/10.7567/1347-4065/ab203c

  • Determination of Current Leakage Sites in Diamond p–n Junction Reviewed

    Takuya Murooka, Hitoshi Umezawa, Toshiharu Makino, Masahiko Ogura, Hiromitsu Kato, Satoshi Yamasaki, Takayuki Iwasaki, Julien Pernot, Mutsuko Hatano

    physica status solidi (a)   216 ( 21 )   1900243   2019.7

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    DOI： 10.1002/pssa.201900243

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  • Effect of Si, Ge and Sn dopant elements on structure and photoluminescence of nano- and microdiamonds synthesized from organic compounds Reviewed

    E.A. Ekimov, M.V. Kondrin, V.S. Krivobok, A.A. Khomich, I.I. Vlasov, R.A. Khmelnitskiy, T. Iwasaki, M. Hatano

    Diamond and Related Materials   93   75 - 83   2019.1

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    DOI： 10.1016/j.diamond.2019.01.029

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  • Extending coherence time of macro-scale diamond magnetometer by dynamical decoupling with coplanar waveguide resonator Reviewed

    Y. Masuyama, K. Mizuno, H. Ozawa, H. Ishiwata, Y. Hatano, T. Ohshima, T. Iwasaki, M. Hatano

    Review of Scientific Instruments   89 ( 12 )   125007 - 125007   2018.12

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    DOI： 10.1063/1.5047078

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  • Wide-field diamond magnetometry with millihertz frequency resolution and nanotesla sensitivity Reviewed

    Kosuke Mizuno, Makoto Nakajima, Hitoshi Ishiwata, Yuta Masuyama, Takayuki Iwasaki, Mutsuko Hatano

    AIP Advances   8 ( 12 )   125316 - 125316   2018.12

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    DOI： 10.1063/1.5048265

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  • Magnetic Field Imaging of Superparamagnetic Particles Using High-Density, Perfectly Oriented NV Centers in Diamond CVD Film Reviewed

    Yuji Hatano, Takeharu Sekiguchi, Takayuki Iwasaki, Mutsuko Hatano, Yoshie Harada

    physica status solidi (a)   215 ( 22 )   1800254 - 1800254   2018.11

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    DOI： 10.1002/pssa.201800254

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  • Improving the electron spin properties of nitrogen-vacancy centres in nanodiamonds by near-field etching Reviewed

    F. Brandenburg, R. Nagumo, K. Saichi, K. Tahara, T. Iwasaki, M. Hatano, F. Jelezko, R. Igarashi, T. Yatsui

    Scientific Reports   8 ( 1 )   15847   2018.10

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    DOI： 10.1038/s41598-018-34158-4

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  • Thermal Stability of Perfectly Aligned Nitrogen‐Vacancy Centers for High Sensitive Magnetometers Reviewed

    Hayato Ozawa, Hitoshi Ishiwata, Mutsuko Hatano, Takayuki Iwasaki

    physica status solidi (a)   215 ( 22 )   1800342 - 1800342   2018.9

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    DOI： 10.1002/pssa.201800342

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  • In situ bias current monitoring of nucleation for epitaxial diamonds on 3C-SiC/Si substrates Reviewed

    Junya Yaita, Takeru Suto, Meralys-Reyes Natal, Stephen E. Saddow, Mutsuko Hatano, Takayuki Iwasaki

    Diamond and Related Materials   88   158 - 162   2018.7

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    DOI： 10.1016/j.diamond.2018.07.011

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  • Preferentially aligned nitrogen-vacancy centers in heteroepitaxial (111) diamonds on Si substrates via 3C-SiC intermediate layers Reviewed

    Junya Yaita, Takeyuki Tsuji, Mutsuko Hatano, Takayuki Iwasaki

    APPLIED PHYSICS EXPRESS   11   045501   2018.4

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    DOI： 10.7567/APEX.11.045501

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  • Charge-state control of ensemble of nitrogen vacancy centers by n-i-n diamond junctions

    Maki Shimizu, Toshiharu Makino, Takayuki Iwasaki, Kosuke Tahara, Hiromitsu Kato, Norikazu Mizuochi, Satoshi Yamasaki, Mutsuko Hatano

    APPLIED PHYSICS EXPRESS   11 ( 3 )   2018.3

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    DOI： 10.7567/APEX.11.033004

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  • Tin-Vacancy Quantum Emitters in Diamond Reviewed

    Takayuki Iwasaki, Yoshiyuki Miyamoto, Takashi Taniguchi, Petr Siyushev, Mathias H. Metsch, Fedor Jelezko, Mutsuko Hatano

    PHYSICAL REVIEW LETTERS   119   253601   2017.12

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    DOI： 10.1103/PhysRevLett.119.253601

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  • Observation of Interface Defects in Diamond Lateral p-n-Junction Diodes and Their Effect on Reverse Leakage Current Reviewed

    Takayuki Iwasaki, Taisuke Suwa, Junya Yaita, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Daisuke Takeuchi, Satoshi Yamasaki, Mutsuko Hatano

    IEEE TRANSACTIONS ON ELECTRON DEVICES   64 ( 8 )   3298 - 3302   2017.8

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    DOI： 10.1109/TED.2017.2718508

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  • Photoluminescence excitation spectroscopy of SiV−and GeV−color center in diamond Reviewed

    Stefan Häußler, Gergő Thiering, Andreas Dietrich, Niklas Waasem, Tokuyuki Teraji, Junichi Isoya, Takayuki Iwasaki, Mutsuko Hatano, Fedor Jelezko, Adam Gali, Alexander Kubanek

    New Journal of Physics   19 ( 6 )   063036 - 063036   2017.7

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    Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

    DOI： 10.1088/1367-2630/aa73e5

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  • Perfectly aligned shallow ensemble nitrogen-vacancy centers in (111) diamond

    Hitoshi Ishiwata, Makoto Nakajima, Kosuke Tahara, Hayato Ozawa, Takayuki Iwasaki, Mutsuko Hatano

    APPLIED PHYSICS LETTERS   111 ( 4 )   2017.7

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    DOI： 10.1063/1.4993160

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  • Formation of perfectly aligned nitrogen-vacancy-center ensembles in chemical-vapor-deposition-grown diamond (111) Reviewed

    Hayato Ozawa, Kosuke Tahara, Hitoshi Ishiwata, Mutsuko Hatano, Takayuki Iwasaki

    APPLIED PHYSICS EXPRESS   10   045501   2017.4

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    DOI： 10.7567/APEX.10.045501

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  • Influence of high-power density plasma on heteroepitaxial diamond nucleation on 3C-SiC surface

    Junya Yaita, Meralys Natal, Stephen E. Saddow, Mutsuko Hatano, Takayuki Iwasaki

    APPLIED PHYSICS EXPRESS   10 ( 4 )   2017.4

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    DOI： 10.7567/APEX.10.045502

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  • Direct Nanoscale Sensing of the Internal Electric Field in Operating Semiconductor Devices Using Single Electron Spins

    Takayuki Iwasaki, Wataru Naruki, Kosuke Tahara, Toshiharu Makino, Hiromitsu Kato, Masahiko Ogura, Daisuke Takeuchi, Satoshi Yamasaki, Mutsuko Hatano

    ACS NANO   11 ( 2 )   1238 - 1245   2017.2

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    DOI： 10.1021/acsnano.6b04460

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  • Highly oriented diamond (111) films synthesized by pulse bias-enhanced nucleation and epitaxial grain selection on a 3C-SiC/Si (111) substrate

    Takeru Suto, Junya Yaita, Takayuki Iwasaki, Mutsuko Hatano

    APPLIED PHYSICS LETTERS   110 ( 6 )   2017.2

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    DOI： 10.1063/1.4975630

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  • High-Temperature Bipolar-Mode Operation of Normally-Off Diamond JFET

    Takayuki Iwasaki, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Daisuke Takeuchi, Satoshi Yamasaki, Andmutsuko Hatano

    IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY   5 ( 1 )   95 - 99   2017.1

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    DOI： 10.1109/JEDS.2016.2624301

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  • Normally-Off Diamond Junction Field-Effect Transistors With Submicrometer Channel

    Taisuke Suwa, Takayuki Iwasaki, Kazuki Sato, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Daisuke Takeuchi, Satoshi Yamasaki, Mutsuko Hatano

    IEEE ELECTRON DEVICE LETTERS   37 ( 2 )   209 - 211   2016.2

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    DOI： 10.1109/LED.2015.2513074

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  • Fabrication of diamond lateral p-n junction diodes on (111) substrates

    Kazuki Sato, Takayuki Iwasaki, Maki Shimizu, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Daisuke Takeuchi, Satoshi Yamasaki, Mutsuko Hatano

    PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE   212 ( 11 )   2548 - 2552   2015.11

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    DOI： 10.1002/pssa.201532266

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  • Quantifying selective alignment of ensemble nitrogen-vacancy centers in (111) diamond

    Kosuke Tahara, Hayato Ozawa, Takayuki Iwasaki, Norikazu Mizuochi, Mutsuko Hatano

    APPLIED PHYSICS LETTERS   107 ( 19 )   2015.11

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    DOI： 10.1063/1.4935709

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  • Charge state modulation of nitrogen vacancy centers in diamond by applying a forward voltage across a p–i–n junction Reviewed

    M. Shimizu, T. Makino, T. Iwasaki, J. Hasegawa, K. Tahara, W. Naruki, H. Kato, S. Yamasaki, M. Hatano

    Diamond and Related Materials   63   192 - 196   2015.10

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    DOI： 10.1016/j.diamond.2015.10.022

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  • Germanium-Vacancy Single Color Centers in Diamond Reviewed

    Takayuki Iwasaki, Fumitaka Ishibashi, Yoshiyuki Miyamoto, Yuki Doi, Satoshi Kobayashi, Takehide Miyazaki, Kosuke Tahara, Kay D. Jahnke, Lachlan J. Rogers, Boris Naydenov, Fedor Jelezko, Satoshi Yamasaki, Shinji Nagamachi, Toshiro Inubushi, Norikazu Mizuochi, Mutsuko Hatano

    SCIENTIFIC REPORTS   5   12882   2015.8

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    DOI： 10.1038/srep12882

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  • Photoelectrochemical CO2 reduction on 3C-SiC photoanode in aqueous solution

    Jun Tae Song, Takayuki Iwasaki, Mutsuko Hatano

    JAPANESE JOURNAL OF APPLIED PHYSICS   54 ( 4 )   2015.4

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    DOI： 10.7567/JJAP.54.04DR05

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  • Heteroepitaxial growth of diamond films on 3C-SiC/Si substrates with utilization of antenna-edge microwave plasma CVD for nucleation

    Junya Yaita, Takayuki Iwasaki, Meralys Natal, Stephen E. Saddow, Mutsuko Hatano

    JAPANESE JOURNAL OF APPLIED PHYSICS   54 ( 4 )   2015.4

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    DOI： 10.7567/JJAP.54.04DH13

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  • Analysis of effect of gate oxidation at SiC MOS interface on threshold-voltage shift using deep-level transient spectroscopy

    Hasegawa Junichi, Noguchi Munetaka, Furuhashi Masayuki, Nakata Shuhei, Iwasaki Takayuki, Kodera Tetsuo, Nishimura Tadashi, Hatano Mutsuko

    Jpn. J. Appl. Phys.   54 ( 4 )   04DP05   2015.1

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    In this study, we investigate the influence of wet oxidation after nitridation of a gate oxide on the interface states in SiC metal–oxide–semiconductor field-effect transistors (MOSFETs). We used deep-level transient spectroscopy (DLTS) to clarify the mechanism behind the positive shift in the threshold voltage after wet oxidation without any significant decrease in the mobility. We applied DLTS using a small pulse to obtain the depth profile of the states. We found that the density of deep-level states near the interface on the SiC side increased after wet oxidation at 600 and 800 °C, whereas the density of shallow states did not increase. This result indicates that the increase in the deep-level states is related to the threshold-voltage shift, and there is no degradation in the mobility.

    DOI： 10.7567/JJAP.54.04DP05

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  • Fluorinated Graphene FETs Controlled by Ionic Liquid Gate

    Satoko Furuyama, Kosuke Tahara, Takayuki Iwasaki, Akihiro Matsutani, Mutsuko Hatano

    JOURNAL OF DISPLAY TECHNOLOGY   10 ( 11 )   962 - 965   2014.11

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    DOI： 10.1109/JDT.2014.2332636

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  • Polarization-controlled dressed-photon-phonon etching of patterned diamond structures

    Takashi Yatsui, Daisuke Takeuchi, Satoshi Koizumi, Kazuki Sato, Kohei Tsuzuki, Takayuki Iwasaki, Mutsuko Hatano, Toshiharu Makino, Masahiko Ogura, Hiromitsu Kato, Hideyo Okushi, Satoshi Yamasaki

    PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE   211 ( 10 )   2339 - 2342   2014.10

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    DOI： 10.1002/pssa.201431161

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  • Formation and structural analysis of twisted bilayer graphene on Ni(111) thin flims

    Takayuki Iwasaki, Alexei A. Zakharov, Thomas Eelbo, Marta Wasniowska, Roland Wiesendanger, Jurgen H. Smet, Ulrich Starke

    SURFACE SCIENCE   625   44 - 49   2014.7

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    DOI： 10.1016/j.susc.2014.03.004

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  • Analysis of selective growth of n-type diamond in lateral p-n junction diodes by cross-sectional transmission electron microscopy

    Kazuki Sato, Takayuki Iwasaki, Yuto Hoshino, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Satoshi Yamasaki, Shinichi Nakamura, Kimiyoshi Ichikawa, Atsuhito Sawabe, Mutsuko Hatano

    JAPANESE JOURNAL OF APPLIED PHYSICS   53 ( 5 )   2014.5

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    DOI： 10.7567/JJAP.53.05FP01

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  • Pt co-catalyst effect on photoelectrochemical properties of 3C-SiC photo-anode

    Jun Tae Song, Takayuki Iwasaki, Mutsuko Hatano

    JAPANESE JOURNAL OF APPLIED PHYSICS   53 ( 5 )   2014.5

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    DOI： 10.7567/JJAP.53.05FZ04

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  • 600 V Diamond Junction Field-Effect Transistors Operated at 200 degrees C

    Takayuki Iwasaki, Junya Yaita, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Daisuke Takeuchi, Hideyo Okushi, Satoshi Yamasaki, Mutsuko Hatano

    IEEE ELECTRON DEVICE LETTERS   35 ( 2 )   241 - 243   2014.2

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    DOI： 10.1109/LED.2013.2294969

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  • Improved visible light driven photoelectrochemical properties of 3C-SiC semiconductor with Pt nanoparticles for hydrogen generation Reviewed

    Jun Tae Song, Hisanori Mashiko, Masayuki Kamiya, Yoshifumi Nakamine, Akira Ohtomo, Takayuki Iwasaki, Mutsuko Hatano

    APPLIED PHYSICS LETTERS   103 ( 21 )   2013.11

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    DOI： 10.1063/1.4832333

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  • High-Temperature Operation of Diamond Junction Field-Effect Transistors With Lateral p-n Junctions

    Takayuki Iwasaki, Yuto Hoshino, Kohei Tsuzuki, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Daisuke Takeuchi, Hideyo Okushi, Satoshi Yamasaki, Mutsuko Hatano

    IEEE ELECTRON DEVICE LETTERS   34 ( 9 )   1175 - 1177   2013.9

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    DOI： 10.1109/LED.2013.2271377

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  • Asymmetric transport property of fluorinated graphene

    Kosuke Tahara, Takayuki Iwasaki, Satoko Furuyama, Akihiro Matsutani, Mutsuko Hatano

    APPLIED PHYSICS LETTERS   103 ( 14 )   2013.9

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    DOI： 10.1063/1.4823798

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  • Fluorination of Graphene by Reactive Ion Etching System Using Ar/ F-2 Plasma

    Akihiro Matsutani, Kousuke Tahara, Takayuki Iwasaki, Mutsuko Hatano

    JAPANESE JOURNAL OF APPLIED PHYSICS   52 ( 6 )   2013.6

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    DOI： 10.7567/JJAP.52.06GD11

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  • Effect of radical fluorination on mono- and bi-layer graphene in Ar/F 2 plasma Reviewed

    K. Tahara, T. Iwasaki, A. Matsutani, M. Hatano

    Applied Physics Letters   101 ( 16 )   2012.10

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    DOI： 10.1063/1.4760268

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  • Electrical properties of lateral p-n junction diodes fabricated by selective growth of n plus diamond

    Yuto Hoshino, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Takayuki Iwasaki, Mutsuko Hatano, Satoshi Yamasaki

    PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE   209 ( 9 )   1761 - 1764   2012.9

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    DOI： 10.1002/pssa.201200053

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  • Diamond Junction Field-Effect Transistors with Selectively Grown n(+)-Side Gates

    Takayuki Iwasaki, Yuto Hoshino, Kohei Tsuzuki, Hiromitsu Kato, Toshiharu Makino, Masahiko Ogura, Daisuke Takeuchi, Tsubasa Matsumoto, Hideyo Okushi, Satoshi Yamasaki, Mutsuko Hatano

    APPLIED PHYSICS EXPRESS   5 ( 9 )   2012.9

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    DOI： 10.1143/APEX.5.091301

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  • n型ダイヤモンド半導体の選択成長法を用いた横型接合FET

    都築 康平, 加藤 宙光, 牧野 俊晴, 小倉 政彦, 竹内 大輔, 大串 秀世, 星野 雄斗, 岩崎 孝之, 山崎 聡, 波多野 睦子

    応用物理学会学術講演会講演予稿集   2012.2   1243 - 1243   2012.8

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    DOI： 10.11470/jsapmeeting.2012.2.0_1243

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  • Experimental analysis of charge redistribution due to chemical bonding by high-resolution transmission electron microscopy

    Jannik C. Meyer, Simon Kurasch, Hye Jin Park, Viera Skakalova, Daniela Kuenzel, Axel Gross, Andrey Chuvilin, Gerardo Algara-Siller, Siegmar Roth, Takayuki Iwasaki, Ulrich Starke, Jurgen H. Smet, Ute Kaiser

    NATURE MATERIALS   10 ( 3 )   209 - 215   2011.3

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    DOI： 10.1038/nmat2941

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  • Long-Range Ordered Single-Crystal Graphene on High-Quality Heteroepitaxial Ni Thin Films Grown on MgO(111)

    Takayuki Iwasaki, Hye Jin Park, Mitsuharu Konuma, Dong Su Lee, Jurgen H. Smet, Ulrich Starke

    NANO LETTERS   11 ( 1 )   79 - 84   2011.1

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    DOI： 10.1021/nl102834q

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  • Growth and properties of chemically modified graphene

    Hye Jin Park, Viera Skakalova, Jannik Meyer, Dong Su Lee, Takayuki Iwasaki, Chris Bumby, Ute Kaiser, Siegmar Roth

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   247 ( 11-12 )   2915 - 2919   2010.12

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    DOI： 10.1002/pssb.201000818

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  • Low-temperature synthesis of multiwalled carbon nanotubes by graphite antenna CVD in a hydrogen-free atmosphere

    Daisuke Yokoyama, Takayuki Iwasaki, Kentaro Ishimaru, Shintaro Sato, Mizuhisa Nihei, Yuji Awano, Hiroshi Kawarada

    CARBON   48 ( 3 )   825 - 831   2010.3

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    DOI： 10.1016/j.carbon.2009.10.035

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  • Quasi-Free-Standing Epitaxial Graphene on SiC Obtained by Hydrogen Intercalation Reviewed

    C. Riedl, C. Coletti, T. Iwasaki, A. A. Zakharov, U. Starke

    Physical Review Letters   103 ( 24 )   246804   2009.12

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    DOI： 10.1103/physrevlett.103.246804

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  • Detection of mismatched DNA on partially negatively charged diamond surfaces by optical and potentiometric methods

    Shoma Kuga, Jung-Hoon Yang, Hironori Takahashi, Kazuyuki Hiirama, Takayuki Iwasaki, Hiroshi Kawarada

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   130 ( 40 )   13251 - 13263   2008.10

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    DOI： 10.1021/ja710167z

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  • Enhanced field emission properties of vertically aligned double-walled carbon nanotube arrays

    Guohai Chen, Dong Hoon Shin, Takayuki Iwasaki, Hiroshi Kawarada, Cheol Jin Lee

    NANOTECHNOLOGY   19 ( 41 )   2008.10

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    DOI： 10.1088/0957-4484/19/41/415703

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  • Electrical properties of carbon nanotubes grown at a low temperature for use as interconnects

    Daisuke Yokoyama, Takayuki Iwasaki, Kentaro Ishimaru, Shintaro Sato, Takashi Hyakushima, Mizuhisa Nihei, Yuji Awano, Hiroshi Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS   47 ( 4 )   1985 - 1990   2008.4

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    DOI： 10.1143/JJAP.47.1985

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  • Mechanism analysis of interrupted growth of single-walled carbon nanotube arrays

    Takayuki Iwasaki, John Robertson, Hiroshi Kawarada

    NANO LETTERS   8 ( 3 )   886 - 890   2008.3

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    DOI： 10.1021/nl073119f

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  • Highly selective growth of vertically aligned double-walled carbon nanotubes by a controlled heating method and their electric double-layer capacitor properties

    Takayuki Iwasaki, Tasuku Maki, Daisuke Yokoyama, Hironori Kumagai, Yasuhiro Hashimoto, Takuma Asari, Hiroshi Kawarada

    PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS   2 ( 2 )   53 - 55   2008.3

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    DOI： 10.1002/pssr.200701297

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  • Low temperature grown carbon nanotube interconnects using inner shells by chemical mechanical polishing

    Daisuke Yokoyama, Takayuki Iwasaki, Tsuyoshi Yoshida, Hiroshi Kawarada, Shintaro Sato, Takashi Hyakushima, Mizuhisa Nihei, Yuji Awano

    APPLIED PHYSICS LETTERS   91 ( 26 )   2007.12

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    DOI： 10.1063/1.2824390

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  • Growth of dense single-walled carbon nanotubes in nano-sized silicon dioxide holes for future microelectronics Reviewed

    T. Iwasaki, R. Morikane, T. Edura, M. Tokuda, K. Tsutsui, Y. Wada, H. Kawarada

    Carbon   45 ( 12 )   2351 - 2355   2007.8

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    Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

    DOI： 10.1016/j.carbon.2007.07.013

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  • Growth kinetics of 0.5 cm vertically aligned single-walled carbon nanotubes

    Guofang Zhong, Takayuki Iwasaki, John Robertson, Hiroshi Kawarada

    JOURNAL OF PHYSICAL CHEMISTRY B   111 ( 8 )   1907 - 1910   2007.3

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

    DOI： 10.1021/jp067776s

    Web of Science

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  • Semi-quantitative study on the fabrication of densely packed and vertically aligned single-walled carbon nanotubes

    Guo Fang Zhong, Takayuki Iwasaki, Hiroshi Kawarada

    CARBON   44 ( 10 )   2009 - 2014   2006.8

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

    DOI： 10.1016/j.carbon.2006.01.027

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  • Synthesis of Aligned Single-Walled Carbon Nanotubes by Point-Arc Microwave Plasma Chemical Vapor Deposition

    IWASAKI Takayuki, ZHONG Goufang, OHDOMARI Iwao, KAWARADA Hiroshi

    Kakuyūgō kenkyū   81 ( 9 )   665 - 668   2005.9

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    Language：Japanese   Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research  

    It is very important to control the growth orientation of carbon nanotubes (CNTs) on substrates for applications such as field emission devices and CNT-based FETs. Although chemical vapor deposition (CVD) is the most reliable means to this end, there have been few reports on the synthesis of vertically aligned single-walled carbon nanotubes (SWNTs) using the CVD method. In this study, we demonstrate the low temperature synthesis of extremelydense and vertically aligned SWNTs deposited by point-arc microwave plasma CVD.

    DOI： 10.1585/jspf.81.665

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    Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10456024

  • Direct Evidence for Root Growth of Vertically Aligned Single-Walled Carbon Nanotubes by Microwave Plasma Chemical Vapor Deposition Reviewed

    Takayuki Iwasaki, Goufang Zhong, Takumi Aikawa, Tsuyoshi Yoshida, Hiroshi Kawarada

    The Journal of Physical Chemistry B   109 ( 42 )   19556 - 19559   2005.9

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    Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

    DOI： 10.1021/jp054465t

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  • Low Temperature Synthesis of Extremely Dense and Vertically Aligned Single-Walled Carbon Nanotubes Reviewed

    Guofang Zhong, Takayuki Iwasaki, Kotaro Honda, Yukio Furukawa, Iwao Ohdomari, Hiroshi Kawarada

    Japanese Journal of Applied Physics   44 ( 4A )   1558 - 1561   2005.4

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

    A novel point-arc microwave plasma chemical vapor deposition (CVD) apparatus was employed to grow single-walled carbon nanotubes (SWNTs) on Si substrates coated with a sandwich-like nano-layer structure of 0.7 nm Al2O3 (top)/0.5 nm Fe/5–70 nm Al2O3 by conventional high frequency sputtering. The growth of extremely dense and vertically aligned SWNTs with an almost constant growth rate of 270 μm/h within 40 min at a temperature as low as 600°C was demonstrated for the first time. The volume density of the as-grown SWNT films is as higher as 66 kg/m3.

    DOI： 10.1143/jjap.44.1558

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  • Very High Yield Growth of Vertically Aligned Single-Walled Carbon Nanotubes by Point-Arc Microwave Plasma CVD Reviewed

    G. F. Zhong, T. Iwasaki, K. Honda, Y. Furukawa, I. Ohdomari, H. Kawarada

    Chemical Vapor Deposition   11 ( 3 )   127 - 130   2005.3

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    Publishing type：Research paper (scientific journal)   Publisher：Wiley  

    DOI： 10.1002/cvde.200404197

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  • Synthesis of highly oriented and dense conical carbon nanofibers by a DC bias-enhanced microwave plasma CVD method Reviewed

    Goufang Zhong, Takayuki Iwasaki, Hiroshi Kawarada, Iwao Ohdomari

    Thin Solid Films   464-465   315 - 318   2004.8

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    Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

    DOI： 10.1016/j.tsf.2004.06.051

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MISC

  • ダイヤモンドNVセンタを用いた心磁図

    桑波田晃弘, 桑波田晃弘, 荒井慧悟, 西谷大祐, 藤崎伊久哉, 松木亮磨, 西尾有輝, 辛宗浩, 曹馨雨, 波多野雄治, 小野田忍, 眞榮力, 宮川仁, 谷口尚, 山崎正俊, 山崎正俊, 寺地徳之, 大島武, 波多野睦子, 関野正樹, 岩崎孝之

    日本生体医工学会大会プログラム・抄録集(Web)   61st ( Abstract )   101_1 - 101_1   2022

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    Language：Japanese   Publisher：公益社団法人 日本生体医工学会  

    癌や脳血管障害とならんで、世界の主要な死因の1つは心臓病である。心房細動、心室頻脈などの心不全は、神経細胞の異常興奮によって局所的に発生する電流伝播の不完全性によって生じると考えられている。心臓内で発生する生体電流伝播の非侵襲イメージングの手法は、超高感度磁気センサを用いた心磁図（心臓磁場の計測）である。生体活動に伴う生体電流から生じる磁場を計測するため、生体活動そのものを観測することが可能である。しかしながら、心臓と磁気センサのスタンドオフ距離が大きくなると、空間分解能が大幅に低下する。既存のSQUID（超電導量子干渉計）やOPM（光ポンピング磁力計）などの高感度磁気センサは、生体適合しない動作温度のため、心臓に対して数mmから1cmの離隔距離が必要であり、cmスケール程度の空間分解能である。本研究では、室温で動作可能なダイヤモンド窒素空孔中心（NVセンタ）に基づく固体量子センシングを駆使した磁場計測システムを開発し、生きているラットのmmスケールの空間分解能での心磁図を実現した。心臓表面1mmまで近接することで、高い空間分解能で心臓内の電流分布・磁場分布をイメージングすることに成功した。本研究は、心房細動、心室頻脈など、心不全の発生と進行のメカニズムを解明など、基礎医学への大きな貢献が期待できる。

    DOI： 10.11239/jsmbe.annual60.101_1

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  • Hybrid integration of Si3N4 grating on a diamond NV substrate using transfer printing

    勝見亮太, 勝見亮太, 飛沢健, 桑波田晃弘, 桑波田晃弘, 岩崎孝之, 波多野睦子, JELEZKO Fedor, 関野正樹, 八井崇, 八井崇

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   69th   2022

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  • Toward biomedical applications of diamond NV quantum sensors

    関野正樹, 伏見幹史, 桑波田晃弘, 桑波田晃弘, 八井崇, 八井崇, 荒井慧悟, 岩崎孝之, 波多野睦子

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   69th   2022

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  • Magnetocardiography using a solid-state quantum sensor

    荒井慧悟, 荒井慧悟, 桑波田晃弘, 桑波田晃弘, 西谷大祐, 藤崎伊久哉, 松木亮磨, 西尾有輝, XIN Zonghao, CAO Xinyu, 波多野雄治, 小野田忍, 真栄力, 宮川仁, 谷口尚, 山崎正俊, 山崎正俊, 寺地徳之, 大島武, 波多野睦子, 波多野睦子, 関野正樹, 岩崎孝之

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   82nd   2021

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  • Numerical optimization and evaluation of a grating coupler on diamond NV bulk substrate

    高橋哲, 勝見亮太, 飛沢健, 佐藤匠, 桑波田晃弘, 五十嵐龍治, 大島武, 増山雄太, 岩崎孝之, 波多野雄治, 波多野睦子, 牧野俊晴, 山崎聡, JELEZKO Fedor, 関野正樹, 八井崇

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   82nd   2021

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  • Label-free phase change detection of lipid bilayers using nanoscale diamond magnetometry

    ISHIWATA Hitoshi, ISHIWATA Hitoshi, WATANABE Hiroshi C., WATANABE Hiroshi C., HANASHIMA Shinya, IWASAKI Takayuki, HATANO Mutsuko

    生物物理(Web)   61 ( Supplement 1-2 )   2021

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  • 手術中における乳がん転移診断用のダイヤモンド量子センサを用いた磁気プローブの開発—Development of a magnetic probe using diamond quantum sensor for intraoperative sentinel lymph node biopsy—マグネティックス 医用・生体工学合同研究会 神経工学&生体磁気

    北泉 隆裕, 桑波田 晃弘, 齋地 康太, 佐藤 匠, 五十嵐 龍治, 大島 武, 増山 雄太, 岩崎 孝之, 波多野 睦子, Fedor Jelezko, 日下部 守昭, 八井 崇, 関野 正樹

    電気学会研究会資料. MAG = The papers of technical meeting on magnetics, IEE Japan / マグネティックス研究会 [編]   2020 ( 16・17・19-46 )   47 - 52   2020.3

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    Language：Japanese   Publisher：電気学会  

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  • Investigation on light extraction efficiency in magnetometer with Nitrogen-Vacancy center in diamond by grating coupler

    佐藤匠, 北泉隆裕, 齋地康太, 桑波田晃弘, 五十嵐龍治, 大島武, 増山雄太, 増山雄太, 岩崎孝之, 波多野睦子, JELEZKO Fedor, 日下部守昭, 日下部守昭, 関野正樹, 八井崇

    Optics & Photonics Japan講演予稿集(CD-ROM)   2019   2019

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  • 転移癌検出に向けたNVセンター磁気プローブの開発

    齋地康太, 佐藤匠, 北泉隆裕, 桑波田晃弘, 関野正樹, 五十嵐龍治, 増山雄太, 増山雄太, 岩崎孝之, 岩崎孝之, 波多野睦子, 波多野睦子, JELEZKO Fedor, 八井崇

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   79th   2018

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  • Low-temperature growth of vertically aligned single-walled carbon nanotubes by radical CVD

    Takayuki Iwasaki, Goufang Zhong, Hiroshi Kawarada

    New Diamond and Frontier Carbon Technology   16 ( 3 )   177 - 184   2006

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    Language：English   Publishing type：Book review, literature introduction, etc.  

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Awards

  • 第24回（令和2年度）丸文研究奨励賞

    2021.3   丸文財団  

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  • 令和2年度 東工大工学院創成的研究賞

    2020.11   東京工業大学  

    波多野睦子教授, 荒井慧悟助教とのグループでの受賞

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  • 令和元年度 手島精一記念研究賞（研究論文賞）

    2020.2   東京工業大学  

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  • 平成31年度 科学技術分野の文部科学大臣表彰 若手科学者賞

    2019.4   文部科学省  

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  • 平成29年度 東工大挑戦的研究賞（学長特別賞）

    2017.7   東京工業大学  

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  • 第4回エヌエフ基金研究開発奨励賞

    2015.11   一般財団法人エヌエフ基金  

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  • 平成25年度東京工業大学手島精一記念研究賞（中村健二郎賞）

    2014.2   東京工業大学  

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    Award type：Award from publisher, newspaper, foundation, etc. 

    カーボン材料の大面積制御合成および電子・エネルギーデバイスへの展開

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  • 第27回ダイヤモンドシンポジウム 優秀講演賞受賞

    2013.11   ニューダイヤモンドフォーラム  

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    Award type：Award from Japanese society, conference, symposium, etc. 

    ダイヤモンド接合型電界効果トランジスタの高温・高電圧特性

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  • 平成24年度工系若手奨励賞

    2012.9   東京工業大学  

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  • 第17回ダイヤモンドシンポジウム 最優秀ポスターセッション賞

    2003.11   ニューダイヤモンドフォーラム  

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Research Projects

  • Charge control and creation of quantum network devices of group-IV vacancy centers in diamond

    Grant number：22H04962  2022.4 - 2027.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (S)

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    Grant amount：\193050000 （ Direct Cost: \148500000 、 Indirect Cost：\44550000 ）

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  • IV族元素を用いたダイヤモンド量子光源の電荷制御技術の研究

    Grant number：22H00210  2022.4 - 2025.3

    日本学術振興会  科学研究費助成事業  基盤研究(A)

    岩崎 孝之, 谷口 尚, 宮本 良之, 牧野 俊晴, 岩本 敏

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    Grant amount：\43030000 （ Direct Cost: \33100000 、 Indirect Cost：\9930000 ）

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  • Quantum sensing of wide bandgap power devices

    Grant number：18H01472  2018.4 - 2022.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    Iwasaki Takayuki

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    Grant amount：\17680000 （ Direct Cost: \13600000 、 Indirect Cost：\4080000 ）

    In this study, we developed basic technologies of quantum sensing for realization of next-generation low loss power devices. In a diamond device, we proposed a novel method to measure electric field vectors using NV centers in diamond, and then, we demonstrated the measurements under the reverse voltage operation. Furthermore, we developed sensing technologies of temperature measurements and electrical detection.

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  • Development of Heteroepitaxial Diamond Wafers by Controlled Buffer Layers

    Grant number：26820110  2014.4 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Young Scientists (B)

    Iwasaki Takayuki

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    Grant amount：\4030000 （ Direct Cost: \3100000 、 Indirect Cost：\930000 ）

    Nucleation and selection technologies of epitaxial diamonds were developed toward fabricating large-area hetero-diamond wafers. The diamond nucleation was performed using a molecular source and bias-enhancement methods. It was revealed that impurities between diamond and a buffer layer caused the formation of non-epitaxial diamonds. The impurities can be suppressed by a high amount of atomic hydrogen generated in a high power density plasma, leading to improvement of the orientation of (100) diamonds. On a (111) face, epitaxial diamonds were obtained with a combination of short-time bias treatment and oxygen addition. Finally, highly-oriented diamond films were achieved on both the (100) and (111) crystal faces.

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  • Ultra-low power consumption devices utilizing new two-dimensional diamond film

    Grant number：26630125  2014.4 - 2016.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Exploratory Research

    Hatano Mutsuko, IWASAKI Takayuki, MATSUTANI Akihiro

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    Grant amount：\4030000 （ Direct Cost: \3100000 、 Indirect Cost：\930000 ）

    We realize the spin state control of graphene to obtain ultra-low power / functional devices. Graphene is employed as the platforms of spin state control because of small spin-orbit interaction. The key for the spin state
    control is the introduction of paramagnetic impurities. The fluorine impurity controlled the charge and spin current in graphene and we call diamond-sheet. Magnetotransport measurements suggests that spin relaxation time could be controllable by one order of magnitude by gate voltages.
    We have also tried to observe spin Hall effect using non-local resistance measurement of Hallbar device. We found the possibility of the existence of spin Hall effect in diamond-sheet. Further evidence should be provided in the future by using highly sensitive magnetic sensor consists of NV centers in diamond.

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  • Diamond Junction Field-Effct Transistors for Low-Loss Power Device Applications

    Grant number：25289086  2013.4 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    Hatano Mutsuko

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    Grant amount：\17810000 （ Direct Cost: \13700000 、 Indirect Cost：\4110000 ）

    Low power loss power devices greatly contribute to a global environmental energy issues. Diamond semiconductor is an attractive material for next-generation power devices due to its wide band-gap, high breakdown field, and high thermal conductivity. By selective n+-type diamond growth, diamond junction field effect transistors (JFETs) were obtained and we confirmed the superior performances of low on resistance (< 5 mΩcm2) and high electric filed (> 5 MV/cm). To increase the on- current, we proposed bipolar-mode operation of the JFETs. We achieved 4-9 times higher drain currents in the bipolar-mode compared with the unipolar-mode operation at a DC current gain of 10. Furthermore, the bipolar-mode currents at the high temperatures of 473 and 573 K became two orders of magnitude larger than the unipolar-mode current at room temperature with a large DC current gain of 102.the bipolar-mode operation in up to 573 K.

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  • Development of novel buffer layers for heteroepitaxial growth of diamond

    Grant number：24760252  2012.4 - 2014.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Young Scientists (B)

    IWASAKI Takayuki

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    Grant amount：\4290000 （ Direct Cost: \3300000 、 Indirect Cost：\990000 ）

    Development of novel buffer layers and diamond growth were performed for future low-loss diamond power devices. As novel buffer layers, CuNi alloy and fluorinated-graphene have been successfully synthesized. Diamond was grown on the CuNi alloy buffer layers by antenna-edge microwave plasma CVD. Compared with the diamond growth on Cu, a higher density of diamond crystals were obtained on the CuNi film. This is because carbon precursors could be easily desorbed from the Cu surface due to the weak interaction, while carbons have strong interaction with Ni and diamond can be nucleated on the CuNi alloy. Thus, the CuNi alloy buffer layer is more suitable for the diamond growth than on Cu.

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  • Study on fluorinated graphene devices to achieve high-speed and low-power consumption

    Grant number：24656202  2012.4 - 2014.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Exploratory Research

    HATANO Mutsuko, IWASAKI Takayuki

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    Grant amount：\4030000 （ Direct Cost: \3100000 、 Indirect Cost：\930000 ）

    Fluorinated graphene has the possibility to achieve high-speed and low-power consumption devices. We propose a highly controlled fluorination method utilizing fluorine radicals in Ar/F2 plasma. Onset of transition from insulating to metallic conduction is observed in dilute fluorinated graphene. Highly fluorinated graphene shows electron-hole asymmetry in transport properties and local resistivity maximum at the hole conduction region, which are presumably caused by the existence of resonant fluorine impurities. Drastic change of the asymmetric feature occurs after removing fluorine atoms and creating structural defects by thermal annealing. These results suggest that the type of impurities or defects in graphene is detectable by examining asymmetry in transport properties. Moreover, fluorinated graphene FETs with ionic liquid gating were fabricated and lower voltage operation and higher on/off ratio were confirmed.

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  • Development of High Power and Millimeter-long Wave Diamond Transistors Using Two Dimensional Hole Gas

    Grant number：19106006  2007 - 2010

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (S)

    KAWARADA Hiroshi, TACHIKI Minoru, TAKANO Yoshihiko, YANG Jung-hoon, IWASAKI Takayuki

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    Grant amount：\102180000 （ Direct Cost: \78600000 、 Indirect Cost：\23580000 ）

    Metal oxide semiconductor field effect transistors (MOSFETs) have been fabricated on diamond exhibiting high current, high frequency and high temperature performance. The maximum drain current density is above 1 A/mm and the highest transconductance is 400 mS/mm. These values are comparable to those of modern FETs made of Si or III-V semiconductors. Regarding RF performance, the highest cutoff frequency reaches nearly 50 GHz. The power handling capability exceeds those of Si and GaAs at 1 GHz. The operation temperature of diamond MOSFETs increased to be 400℃ indicating the stable operation of diamond transistor. Josephson junction devices composed of superconducting diamonds show the junction characteristic frequency in THz region.

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  • Formation of catalytic nanoparticles on metal electrodes for carbon nanotube interconnects

    Grant number：19860068  2007 - 2008

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Young Scientists (Start-up)

    IWASAKI Takayuki

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    Grant amount：\2653000 （ Direct Cost: \2260000 、 Indirect Cost：\393000 ）

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