九州大学-研究者情報 [稲葉優文 (助教) システム情報科学研究院電気システム工学部門]

1.	M. Inaba, T. Oda, M. Kono, N. Phansiri, T. Morita, S. Nakahara, M. Nakano, J. Suehiro, Effect of mixing ratio on NO2 gas sensor response with SnO2-decorated carbon nanotube channels fabricated by one-step dielectrophoretic assembly, SENSORS AND ACTUATORS B-CHEMICAL, 10.1016/j.snb.2021.130257, 344, 130257, 2021.10.
2.	Masafumi Inaba, Takenori Oda, Masaki Kono, Nisarut Phansiri, Takahiro Morita, Shota Nakahara, Michihiko Nakano, Junya Suehiro, Effect of mixing ratio on NO2 gas sensor response with SnO2-decorated carbon nanotube channels fabricated by one-step dielectrophoretic assembly, Sensors and Actuators B: Chemical, 10.1016/j.snb.2021.130257, 344, 130257-130257, 2021.10, We fabricated nitrogen dioxide (NO2) gas sensors with p-type carbon nanotubes (CNTs) / n-type tin dioxide (SnO2) nanoparticle heterojunctions using one-step dielectrophoretic assembly and investigated the effect of CNT/SnO2 ratio on their NO2 gas detection properties. CNTs and SnO2 nanoparticles were mixed in various ratios, suspended in deionized water, and assembled by dielectrophoresis. The normalized response of fabricated CNT/SnO2 heterojunction gas sensors against 1 ppm NO2 was ∼80 in an N2 atmosphere and ∼20 in artificial air, where UV irradiation was used only for initialization. To reduce the effect of oxygen (O2), we also conducted continuous UV irradiation with various intensities during the initialization and gas detection. The CNT/SnO2 pn heterojunction gas sensor had a maximum normalized response of 19 for 1 ppm NO2 in artificial air, while that of the SnO2 sensor was 3. Furthermore, plotting the gas sensor response as a function of NO2 concentration reveals that the sensor detected an NO2 gas concentration as low as 20 ppb in artificial air..
3.	Masafumi Inaba, Masaki Kono, Takenori Oda, Nisarut Phansiri, Michihiko Nakano, Junya Suehiro, Response properties of nitrogen dioxide gas sensors with tin oxide decorated carbon nanotube channel fabricated by two-step dielectrophoretic assembly, AIP Advances, 10.1063/5.0008188, 10, 5, 055223-055223, 2020.05, Gas sensors with carbon nanotubes (CNTs) and tin dioxide (SnO2) nanoparticles for nitrogen dioxide (NO2) detection are fabricated using a two-step dielectrophoretic (DEP) assembly method, and the NO2 gas detection properties are investigated. For the fabrication of the sensor, CNTs assemble between electrodes by a DEP force, followed by SnO2 nanoparticle decoration also by a DEP assembly method, and the assembled CNTs act as high electric field electrodes. The formed CNT/SnO2 gas sensors exhibit a sharp increase in resistance followed by a gradual decrease upon NO2 exposure. pn hetero-junctions are formed between the CNTs and the SnO2 nanoparticles, and the resistance shift of the depletion region in the CNTs at the pn hetero-junction induces the sharp increase in the resistance..
4.	Masafumi Inaba, Shohei Hayashi, Henan Li, Mikoto Kamimura, Michihiko Nakano, Junya Suehiro, Dielectrophoretic properties of submicron diamond particles in sodium chloride aqueous solution, Japanese Journal of Applied Physics, 10.35848/1347-4065/ab7baf, 59, 4, 046502-046502, 2020.04, Dielectrophoretic (DEP) manipulation of a diamond particle has potential application in the detection of DNA or other bio-molecules. We investigate the fundamental DEP and surface properties of submicron diamond particles. Diamond particles were dispersed in a NaCl solution and dropped on a castle-walled electrode. An AC electric field was applied to determine the DEP crossover frequency as a function of the solution conductivity. The surface conductance of the diamond particles was then evaluated from the parametrical fitting of the crossover frequencies. The diamond surface layer was shown to exhibit a rather high conductance, although bulk diamond is insulative..
5.	Masafumi Inaba, Shohei Hayashi, Henan Li, Mikoto Kamimura, Michihiko Nakano and Junya Suehiro, Dielectrophoretic properties of submicron diamond particles in sodium chloride aqueous solution, Japanese Journal of Applied Physics, 10.35848/1347-4065/ab7baf, 59, 046502, 1-5, 2020.03.
6.	Masafumi Inaba, Takumi Ochiai, Kazuyoshi Ohara, Ryogo Kato, Tasuku Maki, Toshiyuki Ohashi, Hiroshi Kawarada, Correlation between the Carbon Nanotube Growth Rate and Byproducts in Antenna-Type Remote Plasma Chemical Vapor Deposition Observed by Vacuum Ultraviolet Absorption Spectroscopy, Small, 10.1002/smll.201901504, 15, 48, 2019.11, [URL], For sp² or sp³ carbon material growth, it is important to investigate the precursors or intermediates just before growth. In this study, the density of ethylene (C₂H₄) outside the plasma discharge space and just before reaching the carbon nanotube (CNT) growth region is investigated by vacuum ultraviolet absorption spectroscopy for plasma discharge in an antenna-type remote plasma chemical vapor deposition with a CH₄/H₂ system, with which the growth of very long (≈0.5 cm) CNT forests is achieved. Single-wall CNT forests have the potential for application as electrodes in battery cells, vertical wiring for high current applications, and thermal interface materials. It is observed that the plasma discharge decomposes the CH₄ source gas and forms C₂H_x species, which reversibly reform to C₂H₄ in the plasma-off state. In addition, the density of the formed C₂H₄ has a strong correlation to the CNT growth rate. Therefore, the C₂H₄ density is a good indicator of the density of C₂H_x species for CNT growth in the CH₄/H₂ plasma system..
7.	Masafumi Inaba, Hiroshi Kawarada, Yutaka Ohno, Electrical property measurement of two-dimensional hole-gas layer on hydrogen-terminated diamond surface in vacuum-gap-gate structure, Applied Physics Letters, 10.1063/1.5099395, 114, 25, 2019.06, [URL], Hydrogen-terminated diamond metal-insulator-semiconductor field-effect transistors are candidates for power devices that require a high breakdown field and stable, high-frequency operation. A two-dimensional hole-gas layer can form on H-terminated diamond surfaces. To understand the electrical properties of bare H-terminated diamond surfaces, we investigate the surface impurities on a H-terminated diamond surface in a vacuum-gap gate structure, which uses a H-terminated diamond channel and a vacuum gap as gate dielectrics. To obtain a bare surface without surface adsorbate, the device is annealed in a vacuum. The transconductance is increased by removing adsorbates. The mobility and interface-state density at the H-terminated diamond surface with no adsorbates are 25 cm^2 V^-1 s^-1 and 1 × 10^12 cm^-2 eV^-1, respectively..
8.	Nobutaka Oi, Masafumi Inaba, Satoshi Okubo, Ikuto Tsuyuzaki, Taisuke Kageura, Shinobu Onoda, Atsushi Hiraiwa, Hiroshi Kawarada, Vertical-type two-dimensional hole gas diamond metal oxide semiconductor field-effect transistors, Scientific reports, 10.1038/s41598-018-28837-5, 8, 1, 2018.12, [URL], Power semiconductor devices require low on-resistivity and high breakdown voltages simultaneously. Vertical-type metal-oxide-semiconductor field-effect transistors (MOSFETs) meet these requirements, but have been incompleteness in diamond. Here we show vertical-type p-channel diamond MOSFETs with trench structures and drain current densities equivalent to those of n-channel wide bandgap devices for complementary inverters. We use two-dimensional hole gases induced by atomic layer deposited Al2O3 for the channel and drift layers, irrespective of their crystal orientations. The source and gate are on the planar surface, the drift layer is mainly on the sidewall and the drain is the p+ substrate. The maximum drain current density exceeds 200 mA mm^-1 at a 12 μm source-drain distance. On/off ratios of over eight orders of magnitude are demonstrated and the drain current reaches the lower measurement limit in the off-state at room temperature using a nitrogen-doped n-type blocking layer formed using ion implantation and epitaxial growth..
9.	Masafumi Inaba, Kazuyoshi Ohara, Megumi Shibuya, Takumi Ochiai, Daisuke Yokoyama, Wataru Norimatsu, Michiko Kusunoki, Hiroshi Kawarada, Electrical contact properties between carbon nanotube ends and a conductive atomic force microscope tip, Journal of Applied Physics, 10.1063/1.5027849, 123, 24, 2018.06, [URL], Understanding the electrical contact properties of carbon nanotube (CNT) ends is important to use the high conductance of CNTs in the CNT on-axis direction in applications such as through-silicon via structures. In this study, we experimentally evaluated the contact resistivity between single-/multi-walled CNT ends and a metal nanoprobe using conductive atomic force microscopy (C-AFM). To validate the measured end contact resistivity, we compared our experimentally determined value with that obtained from numerical calculations and reported values for side contact resistivity. The contact resistivity normalized by the length of the CNT ends was 0.6-2.4 × 10^6 Ω nm for single-walled CNTs. This range is 1-2 orders of magnitude higher than that determined theoretically. The contact resistivity of a single-walled CNT end with metal normalized by the contact area was 2-3 orders of magnitude lower than that reported for the resistivity of a CNT sidewall/metal contact. For multi-walled CNTs, the measured contact resistivity was one order of magnitude higher than that of a CNT forest grown by remote plasma-enhanced chemical vapor deposition, whereas the contact resistivity of a top metal electrode was similar to that obtained for a single-walled CNT forest..
10.	Masafumi Inaba, Tsubasa Muta, Mikinori Kobayashi, Toshiki Saito, Masanobu Shibata, Daisuke Matsumura, Takuya Kudo, Atsushi Hiraiwa, Hiroshi Kawarada, Hydrogen-terminated diamond vertical-type metal oxide semiconductor field-effect transistors with a trench gate, Applied Physics Letters, 10.1063/1.4958889, 109, 3, 2016.07, [URL], The hydrogen-terminated diamond surface (C-H diamond) has a two-dimensional hole gas (2DHG) layer independent of the crystal orientation. A 2DHG layer is ubiquitously formed on the C-H diamond surface covered by atomic-layer-deposited-Al2O3. Using Al2O3 as a gate oxide, C-H diamond metal oxide semiconductor field-effect transistors (MOSFETs) operate in a trench gate structure where the diamond side-wall acts as a channel. MOSFETs with a side-wall channel exhibit equivalent performance to the lateral C-H diamond MOSFET without a side-wall channel. Here, a vertical-type MOSFET with a drain on the bottom is demonstrated in diamond with channel current modulation by the gate and pinch off..
11.	Masafumi Inaba, Chih Yu Lee, Kazuma Suzuki, Megumi Shibuya, Miho Myodo, Yu Hirano, Wataru Norimatsu, Michiko Kusunoki, Hiroshi Kawarada, Contact Conductivity of Uncapped Carbon Nanotubes Formed by Silicon Carbide Decomposition, Journal of Physical Chemistry C, 10.1021/acs.jpcc.5b11815, 120, 11, 6232-6238, 2016.03, [URL], Understanding of the contact conductivity of carbon nanotubes (CNTs) will contribute to the further application of CNTs for electronic devices, such as thin film transistors whose channel or electrode is made of dispersed CNTs. In this study, we estimated the contact conductivity of a CNT/CNT interface from the in-plane conductivity of an uncapped CNT forest on SiC. Investigation of the electrical properties of dense CNT forests is also important to enable their electrical application. The in-plane conductivity of a dense CNT forest on silicon carbide normalized by its thickness was measured to be 50 S/cm, which is two to three orders of magnitude lower than the conductivity of a CNT yarn. It was also found that both the CNT cap region and the CNT bulk region exhibit in-plane conductivity. The contact conductivity of CNTs was estimated from the in-plane conductivity in the bulk region. Dense and uncapped CNT forest can be approximated by a conductive mesh, in which each conductive branch corresponds to the CNT/CNT contact conductance. The evaluated contact conductivity was in good agreement with that calculated from the tunneling effect..
12.	Masafumi Inaba, Kazuma Suzuki, Megumi Shibuya, Chih Yu Lee, Yoshiho Masuda, Naoya Tomatsu, Wataru Norimatsu, Atsushi Hiraiwa, Michiko Kusunoki, Hiroshi Kawarada, Very low Schottky barrier height at carbon nanotube and silicon carbide interface, Applied Physics Letters, 10.1063/1.4916248, 106, 12, 2015.03, [URL], Electrical contacts to silicon carbide with low contact resistivity and high current durability are crucial for future SiC power devices, especially miniaturized vertical-type devices. A carbon nanotube (CNT) forest formed by silicon carbide (SiC) decomposition is a densely packed forest, and is ideal for use as a heat-dissipative ohmic contact in SiC power transistors. The contact resistivity and Schottky barrier height in a Ti/CNT/SiC system with various SiC dopant concentrations were evaluated in this study. Contact resistivity was evaluated in relation to contact area. The Schottky barrier height was calculated from the contact resistivity. As a result, the Ti/CNT/SiC contact resistivity at a dopant concentration of 3 × 10^18 cm-3 was estimated to be ∼1.3 × 10^-4 Ω cm2 and the Schottky barrier height of the CNT/SiC contact was in the range of 0.40-0.45 eV. The resistivity is relatively low for SiC contacts, showing that CNTs have the potential to be a good ohmic contact material for SiC power electronic devices..

主要総説, 論評, 解説, 書評, 報告書等

全てを見る→

主要学会発表等

全てを見る→

1.	稲葉優文, 新規熱伝導性フィラーの開発と電界整列による放熱シートの機能付加, 九州大学　新技術説明会, 2023.10.

特許出願・取得

特許出願件数 3件

特許登録件数 0件

学会活動

所属学会名

フィラー研究会

九州パワーアカデミー

フラーレン・ナノチューブ・グラフェン学会

ニューダイヤモンドフォーラム

電気学会

応用物理学会

学協会役員等への就任

2022.03～2023.03, 第41回電子材料シンポジウム, 運営委員.

2021.05～2023.05, ニューダイヤモンドフォーラム, 運営委員.

2021.03～2023.03, 第40回電子材料シンポジウム, 運営委員.

2020.02～2022.03, ダイヤモンド・DLC関連若手会, 幹事.

学会大会・会議・シンポジウム等における役割

2022.06.06～2022.06.09, 15th International Conference on New Diamond and Nano Carbons (NDNC) 2022, Program Committee member.

2022.03.02～2022.03.04, 第62回フラーレン・ナノチューブ・グラフェン総合シンポジウム , 座長.

2021.03.04～2021.03.04, 第10回フラーレン・ナノチューブグラフェン若手研究会, 幹事.

2020.11.20～2020.11.20, 第1回ダイヤモンド・DLC関連若手研究会, 幹事.

2020.09.26～2020.09.27, 電気・情報関係学会九州支部第73回連合大会, 座長.

2020.09.26～2020.09.27, 電気・情報関係学会九州支部第73回連合大会, プログラム編集委員.

2019.09.27～2019.09.28, 電気・情報関係学会九州支部第72回連合大会, 座長.

2019.09.27～2019.09.28, 電気・情報関係学会九州支部第72回連合大会, プログラム編集委員.

学術論文等の審査

年度	外国語雑誌査読論文数	日本語雑誌査読論文数	国際会議録査読論文数	国内会議録査読論文数	合計
2023年度	3				3
2020年度	7				7

受賞

パワーアカデミー萌芽研究優秀賞, パワーアカデミー, 2021.03.

優秀ポスター賞, 第32回ダイヤモンドシンポジウム, 2018.11.

EMS賞, 電子材料シンポジウム, 2016.07.

研究資金

科学研究費補助金の採択状況(文部科学省、日本学術振興会)

2023年度～2026年度, 基盤研究(B), 分担, ファンデルワールス材料で拓く熱輸送の時空間制御技術の確立.

2022年度～2024年度, 基盤研究(C), 代表, 均質誘電泳動法の開発と半導体カーボンナノチューブガスセンサへの応用.

2020年度～2021年度, 若手研究, 代表, 絶縁・フレキシブル・高熱伝導なダイヤモンド複合伝熱シート.

2018年度～2019年度, 若手研究, 代表, 量子コンピューティングに向けたダイヤモンドオンチップ光回路に関する研究.

2017年度～2018年度, 特別研究員奨励費, 代表, ２次元正孔ガスを用いたダイヤモンドＭＯＳＦＥＴのチャネル移動度向上.

2014年度～2018年度, 基盤研究(S), 分担, ダイヤモンド表面キャリアによる電子スピン制御とその生体分子核スピン観測への応用.

2014年度～2015年度, 挑戦的萌芽研究, 分担, クローニングによるSiC上のジグザグ型カーボンナノチューブ・フォレストの長尺化.

2014年度～2014年度, 基盤研究(A), 分担, ダイヤモンド表面近傍の電子スピン制御による単一核スピンの観測.

日本学術振興会への採択状況(科学研究費補助金以外)

2017年度～2018年度, 特別研究員, 代表, 2次元正孔ガスを用いたダイヤモンドMOSFETのチャネル移動度向上.

競争的資金(受託研究を含む)の採択状況

2020年度～2021年度, AUN/SEED-Net Special Program for Research against COVID-19 (SPRAC), 分担, AlGaN/GaN High-Electron-Mobility Transistor (HEMT) for SARS-CoV-2(COVID-19) Rapid Detection.

寄附金の受入状況

2023年度, 泉科学技術振興財団研究助成, 1枚で熱分布を作り出す熱配線シートの開発.

2023年度, スズキ財団, ダイヤモンドフレークの創成と放熱材料応用.

2023年度, 西部ガス, 両極性カーボンナノチューブFETを用いた超高速・高感度NO2検出.

2022年度, 松籟科学技術振興財団, ダイヤモンドフィラーを用いたフレキシブル伝熱シートの内部構造と熱伝導特性向上.

2022年度, パロマ環境技術開発財団, カーボンナノチューブ電界効果トランジスタによるダイナミックレンジNO2ガスセンサの開発と応答原理解明.

2022年度, 豊田理研スカラー, 広域誘電泳動集積によるスピンゼーベック発電素子の開発.

2022年度, 池谷科学技術振興財団, 広域誘電泳動集積技術の開発とスピンゼーベック発電素子への応用.

2021年度, 旭硝子財団, 研究助成／光の不平等電界による低次元半導体微粒子の配向技術の確立.

2020年度, 高橋産業経済研究財団, 研究助成／ダイヤモンド微粒子の誘電泳動技術の確立とフレキシブル伝熱シートへの応用.

2019年度, パワーアカデミー, 研究助成／フィラーに微粒子ダイヤモンドを用いた、高熱伝導・高絶縁・フレキシブルな伝熱シートの開発.

2019年度, 泉科学技術振興財団, 研究助成／フレキシブル伝熱シートの高熱伝導率化と内部構造評価.