KEIO RESEARCHERS INFORMATION SYSTEM

Career 【 Display / hide 】

Career 【 Display / hide 】

• 2013.04

  -

  2014.03

  Keio University, Faculty of Science and Technology, 助教

• 2014.04

  -

  2015.03

  日本学術振興会, 特別研究員(DC2)

• 2015.04

  -

  2016.03

  日本学術振興会, 特別研究員(PD)

• 2016.04

  -

  2019.03

  Keio University, Faculty of Science and Technology, 助教

• 2019.04

  -

  2023.03

  The University of Tokyo, The Graduate School of Engineering, Department of Materials Engineering, 助教

display all >>

Research Areas 【 Display / hide 】

Research Areas 【 Display / hide 】

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

• Nanotechnology/Materials / Inorganic materials and properties

Research Keywords 【 Display / hide 】

Research Keywords 【 Display / hide 】

• 半導体デバイス

• 半導体工学

• 半導体物性

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Density functional tight binding parametrization of CoSn toward high-throughput transport simulation

  Takahisa Tanaka

  Materials Letters (Elsevier BV)  413   140498 - 140498 2026.06

  Lead author, Last author, Corresponding author, Accepted,  ISSN  0167577X

  　View Summary

  In this study, density functional tight binding (DFTB) parameter for CoSn were developed toward high-throughput atomistic transport simulation. The developed DFTB parameters based on Bayesian optimization reproduced band structure of hcp Co, α-Sn, β-Sn and CoSn. To validate capability of transport simulation with the developed DFTB parameters, anisotropic bulk resistivity of CoSn was simulated by DFTB based non equilibrium Green's function simulation with frozen phonon approach. Calculated resistivity along a-axis ρ<inf>a</inf> = 40.0 μΩ∙cm and c-axis ρ<inf>c</inf> = 3.2 μΩ∙cm successfully reproduced experimentally reported values.

  • Access to Document (DOI)

• Fabrication of Highly Sensitive Graphene Electric Field Sensor by Fowler–Nordheim Injection in SiO ₂

  Soko Tsutsumi, Takashi Ikuta, Takahisa Tanaka

  IEEE Sensors Letters (Institute of Electrical and Electronics Engineers (IEEE))  10 ( 3 )  2026

  Last author, Corresponding author, Accepted

  　View Summary

  Electric field sensing can be used for the early prediction of lightning. In this study, we have suggested the method of sensitivity enhancement of graphene electric field sensor by Fowler–Nordheim (FN) injection into SiO<inf>2</inf> under the graphene. The electric field sensing mechanism relies on the transfer of electrons between graphene and the interface trap states at the SiO<inf>2</inf>/graphene interface. The charge transfer alters carrier concentration in the graphene channel, which is reflected as a change in the drain current. The FN injection increases the interface trap states. Although time constant of charge transfer between graphene and the interface trap states was slightly degraded, lower limit of detection and sensor response were improved by the FN injection; the sensor response at 1 kV/m after 30 s of FN injection was 1230% of that before FN injection. The experimental result indicates the proposed method by FN injection is widely applicable for sensitivity improvement of electric field sensor composed of 2-D materials.

  • Access to Document (DOI)

• Flow‐Adaptive Gas Sensing Enabled Using a Uniform Au Nanosheet Sensor Array and a Neural Network Inference

  Taro Kato, Takahisa Tanaka, Yusuke Hamanaka, Ryo Toyoshima, Ken Uchida

  Advanced Materials Technologies (Wiley)   2026

  Accepted,  ISSN  2365-709X

  　View Summary

  ABSTRACT
  
  Gas sensor responses are considerably affected by gas flow rates, thereby inhibiting the accurate detection of target gas concentrations in variable‐flow applications such as breath analyzers. To address this challenge, a flow‐adaptive sensing system using a spatially distributed array of uniform Au nanosheet sensors was developed. The array layout was designed via computational fluid dynamics (CFD) simulations to generate spatiotemporal signal patterns from the array output upon gas exposure. These patterns were used to train a deep neural network, which accurately estimated gas flow rates and concentrations under various conditions. This system does not require active flow control during operation. The proposed approach employs sensor array design, CFD‐guided layout, and artificial‐intelligence‐based inference to overcome the fundamental limitations of gas sensing. The sensing system can operate reliably under various flow conditions, highlighting the conceptual potential of the array‐based sensing method for use in portable and pumpless gas‐sensing platforms.

  • Access to Document (DOI)

• Numerical studies of size effects on resistivity in an oxidized CuAl ₂ film

  Takahisa Tanaka

  Applied Physics Express (IOP Publishing)   2025.10

  Lead author, Last author, Corresponding author, Accepted,  ISSN  1882-0778

  　View Summary

  Abstract
  
  By atomistic simulations, we investigated effects of oxidation on resistivity of CuAl ₂ , which is expected to be a new interconnect material. Cu/Al/O reactive force field was developed for molecular dynamics (MD) simulations of CuAl ₂ oxidation. From atomic positions of oxidized CuAl ₂ films derived from MD simulations, resistivity was calculated by quantum transport simulations. Calculated resistivity was well reproduced by Fuchs-Sondheimer model with mean free path of 21 nm and surface specularity parameter of 0. Derived mean free path and surface specularity parameter realize precise modeling of interconnect resistivity composed of CuAl ₂ .

  • Access to Document (DOI)

• Low Resistive Ru Thin Film on Dielectrics without Adhesive Liner for Sub-2nm Interconnects

  Hayashi R., Ogawa M., Oshio S., Adachi K., Tanaka T., Tada M.

  2025 IEEE International Interconnect Technology Conference Iitc 2025  2025

  　View Summary

  A low-pressure deposited, low-resistivity Ru thin film enables interconnects without adhesive liners for sub-2nm nodes and beyond. The newly developed low-pressure Ru deposition offers (1) a larger grain size of 14 nm, (2) smaller surface roughness of Ra = 0.16 nm, and the highest film density of 12.1 g/cm³, resulting in a record-low resistivity of 22.45 μΩcm at a thickness of 20 nm in the as-deposited state, without any additional thermal annealing. The 10 nm Ru thin film exhibits sufficiently high adhesive strength on SiO<inf>2</inf> without the need for adhesive liners. The effective resistance, including liner resistance, is reduced by 15.9% compared to that with a Ta adhesive liner. The Ru thin film without the liner is a strong candidate for future advanced technology nodes.

  • Access to Document (DOI)

display all >>

Papers, etc., Registered in KOARA 【 Display / hide 】

Papers, etc., Registered in KOARA 【 Display / hide 】

• Low power consumption gas sensing based on modulation of sensor response by electric field

  Tanaka, Takahisa

  学事振興資金研究成果実績報告書 (慶應義塾大学)  2023

• Characterization of carrier scattering mechanisms in strained silicon and strained germanium based on the mobility spectrum analysis

  Tanaka, Takahisa

  (慶應義塾大学大学院理工学研究科)  2014

• Characterization of carrier scattering mechanisms in strained silicon and strained germanium based on the mobility spectrum analysis

  Tanaka, Takahisa

  (慶應義塾大学大学院理工学研究科)  2014

• Characterization of carrier scattering mechanisms in strained silicon and strained germanium based on the mobility spectrum analysis

  Tanaka, Takahisa

  (慶應義塾大学大学院理工学研究科)  2014

Presentations 【 Display / hide 】

Presentations 【 Display / hide 】

• Experimental Investigation of Interface Defect Properties in PtOx/ZnO Schottky Diodes by Deep Level Transient Spectroscopy

  M. Matsumura, T. Tanaka, K. Uchida

  34th International Microprocesses and Nanotechnology Conference (MNC), 

  2021.10

• Enhanced electron phonon scattering in Si nanowires covered by oxide

  T. Tanaka, K. Uchida

  240th ECS Meeting, 

  2021.10

• Selective Recognition of Acetone in Air Against Hydrogen By Impedance Measurement of Two-Terminal Electrochemical Sensors Based on Ionic Liquids

  Y. Hamanaka, T. Tanaka, K. Uchida

  240th ECS Meeting, 

  2021.10

• A Wide Range and High Accuracy Sensor Interface with Switching Regulator for Coin-Cell Powered Tiny Wirelesss Sensor Node

  K. Tatehora, Y. Shiiki, S. Nakagawa, T. Tanaka, K. Uchida, H. Ishikuro

  IEEE International Symposium on Circuits and Systems (ISCAS), 

  2020.10

• Experimental Evidence for Temperature Dependence of Adsorbate-induced Scattering in Metal Nanosheets and Its Implication to Gas Sensing Applications

  Taro Kato, Takahisa Tanaka, Takeaki Yajima, Ken Uchida

  2020 International Conference on Solid State Devices and Materials, 

  2020.09

display all >>

Research Projects of Competitive Funds, etc. 【 Display / hide 】

Research Projects of Competitive Funds, etc. 【 Display / hide 】

• イオン液体のインピーダンスによる高選択的マルチガスセンシング

  2024.04

  -

  2027.03

  基盤研究(C), Principal investigator

• 半導体表面/界面における特異な電子フォノン散乱の起源の解明

  2019.04

  -

  2023.03

  日本学術振興会, 科学研究費助成事業, 若手研究, No Setting

  　View Summary

  本年度は主に、1)シリコンナノ構造界面におけるフォノン散乱の変調と2)金属系材料の抵抗率計算で進展があった。
  1)シリコンナノ構造界面におけるフォノン散乱の変調については、昨年度まで実施していた分子動力学計算・強結合近似計算・量子輸送計算を連携した手法を用いて移動度の温度依存性を計算した。その結果、酸化膜で被覆されたシリコンナノワイヤ中の電子移動度の方が、水素終端シリコンナノワイヤ中の電子移動度よりも強い温度依存性を持つことを明らかにした。これは、昨年度までで判明した酸化膜被覆シリコンナノワイヤにおける電子移動度の劣化が、界面ラフネス由来ではなくフォノン散乱の変調であることを示唆している。一方で、ゲルマニウムナノワイヤに対して同様の計算を実施した場合は、酸化膜の有無は顕著な移動度変化を発生させなかった。これはシリコンとゲルマニウムの機械的特性の違いに起因していると予想されるため、今後検証を行う。
  2)金属系材料の抵抗率計算では、本研究で開発した手法が別種の材料系でも適用可能かを検討した。白金ナノシートでは、表面に吸着した水素と酸素の量に依存して電気抵抗が変化するため、水素ガスセンサとして用いられる。しかし、フォノン散乱と吸着ガスによる散乱が共存する系を定量的に解析することは困難であった。本研究では、反応力場に基づく分子動力学計算・密度半関数計算・量子輸送計算を連携することで、半導体ナノ構造と同様にキャリア散乱を取り扱うことに成功した。

• 次世代トランジスタに向けた酸化膜近傍におけるキャリア散乱モデルの確立

  2014.04

  -

  2016.03

  日本学術振興会, 科学研究費助成事業, 特別研究員奨励費, No Setting

  　View Summary

  本研究は，酸化膜近傍におけるキャリア散乱機構のモデリングを行うことを目的としている．最終年度となる本年度は，酸化膜近傍におけるフォノン散乱の変形ポテンシャルのモデリングと，クーロン散乱に影響する酸化膜近傍でのイオン化エネルギーの上昇のモデリングを行った．
  まず，フォノン散乱の変形ポテンシャルのモデリングでは，薄膜Silicon-On-Insulator(SOI)トランジスタ中の移動度の温度依存性を測定した．実験的な移動度の温度依存性に対して計算値を比較することにより，酸化膜近傍の変形ポテンシャル上昇を考慮することが，正確な移動度の温度依存性の再現に必要であることを明らかにした．さらに，変形ポテンシャル上昇を考慮したモデルで，薄膜SOIトランジスタに加えてバルクSiトランジスタとジャンクションレス厚膜SOIトランジスタの移動度も統一的に説明できることを明らかにした．
  また，クーロン散乱に影響する酸化膜近傍のイオン化エネルギー上昇のモデリングでは，薄膜SOIトランジスタ中のイオン化エネルギーをキャリア濃度の温度依存性から実験的に求めた．得られたイオン化エネルギーを計算値と比較することで，任意の不純物濃度における，酸化膜近傍でのイオン化エネルギーを記述するモデルの構築に成功した．このモデルにより，高不純物濃度における酸化膜近傍のイオン化率を評価できるようになったため，クーロン散乱に寄与するイオン化不純物の量をより正確に見積もれると期待される．

Courses Taught 【 Display / hide 】

Courses Taught 【 Display / hide 】

• ELECTRONICS DEVICES

  2026

• GRADUATE RESEARCH ON ENGINEERING AND DESIGN 1

  2026

• FUNDAMENTALS OF ELECTRONICS

  2026

• INTEGRATED NANO-ELECTRONICS

  2026

• GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 1

  2026

display all >>

Committee Experiences 【 Display / hide 】

Committee Experiences 【 Display / hide 】

• 2019

  -

  Present

  Program Committee Members, International Microprocesses and Nanotechnology Conference