研究者詳細 - 石川　健治

論文 - 石川　健治

分割表示 417 件中 261 - 280 件目／全件表示 >>

Reduction of chlorine radical chemical etching of GaN under simultaneous plasma-emitted photon irradiation 査読有り Open Access

Liu, ZC; Imamura, M; Asano, A; Ishikawa, K; Takeda, K; Kondo, H; Oda, O; Sekine, M; Hori, M

APPLIED PHYSICS EXPRESS 10 巻 ( 8 ) 2017年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Express

Surface chemical reactions on the GaN surface with Cl radicals are thermally enhanced in the high-temperature Cl<inf>2</inf> plasma etching of GaN, resulting in the formation of etch pits and thereby, a roughened surface. Simultaneous irradiation of ultraviolet (UV) photons in Cl<inf>2</inf> plasma emissions with wavelengths of 258 and 306nm reduces the surface chemical reactions because of the photodissociation of both Ga and N chlorides, which leads to a suppression of the increase in surface roughness. Compared with Si-related materials, we point out that photon-induced reactions should be taken into account during the plasma processing of wide-bandgap semiconductors.

DOI： 10.7567/APEX.10.086502

Temperature dependence of protection layer formation on organic trench sidewall in H<sub>2</sub>/N<sub>2</sub> plasma etching with control of substrate temperature 査読有り

Fukunaga, Y; Tsutsumi, T; Takeda, K; Kondo, H; Ishikawa, K; Sekine, M; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 7 ) 2017年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

For the etching of organic films in H2/N2 plasma, etched profiles are significantly determined by substrate temperature. Here, we control the substrate temperature variation within 3 °C during processing by modulating the plasma-discharge time. The evolution of the cross-sectional profile of line-and-space patterns was observed every 10s. At 60 and 100 °C, sidewall etching was observed during overetching, but not at 20 °C. During the main etching, the sidewalls were protected by the adsorption of by-products at various temperatures. Moreover, we investigated the temperature dependence of protection layer formation by analyzing the surface components of the organic film. The CN layer formed by N radicals has a protective effect that depends on the components of the CN layer. It was found that the ratio of C-N sp<sup>3</sup> to C-N sp<sup>2</sup> in the sidewall was highest at 100°C. By evaluating the radical contribution to CN layer formation, C-N sp<sup>3</sup> bonds were observed to be formed by ions and radiation-assisted reaction.

DOI： 10.7567/JJAP.56.076202

Intracellular-molecular changes in plasma-irradiated budding yeast cells studied using multiplex coherent anti-Stokes Raman scattering microscopy 査読有り Open Access

Furuta, R; Kurake, N; Ishikawa, K; Takeda, K; Hashizume, H; Kondo, H; Ohta, T; Ito, M; Sekine, M; Hori, M

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 19 巻 ( 21 ) 頁： 13438 - 13442 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physical Chemistry Chemical Physics

Interactions between non-equilibrium atmospheric-pressure plasma (NEAPP) and living cells were examined using multiplex coherent anti-Stokes Raman scattering (CARS) microscopy. Our multiplex CARS analyses revealed that NEAPP irradiation generates short-lived radicals that induce a decrease in the mitochondrial activity of budding yeast cells.

DOI： 10.1039/c7cp00489c

Dry Process FOREWORD 査読有り

Ishikawa, K; Kinoshita, K; Higashi, S; Ichiki, T; Karahashi, K; Kuboi, N

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 6 ) 2017年6月

Hydrogen peroxide sensor based on carbon nanowalls grown by plasma-enhanced chemical vapor deposition 査読有り

Tomatsu, M; Hiramatsu, M; Foord, JS; Kondo, H; Ishikawa, K; Sekine, M; Takeda, K; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 6 ) 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Fabrication of an electrochemical sensor for hydrogen peroxide (H<inf>2</inf>O<inf>4</inf>) detection was demonstrated. H<inf>4</inf>O<inf>2</inf> is a major messenger molecule in various redox-dependent cellular signaling transductions. Therefore, sensitive detection of H<inf>2</inf>O<inf>2</inf> is greatly important in health inspection and environmental protection. Carbon nanowalls (CNWs) are composed of few-layer graphenes standing almost vertically on a substrate forming a three-dimensional structure. In this work, CNWs were used as a platform for H<inf>2</inf>O<inf>2</inf> sensing, which is based on the large surface area of conducting carbon and surface decoration with platinum (Pt) nanoparticles (NPs). CNWs were grown on carbon fiber paper (CFP) by inductively coupled plasma-enhanced chemical vapor deposition to increase the surface area. Then, the CNW surface was decorated with Pt-NPs by the reduction of H<inf>2</inf>PtCl<inf>6</inf>. Cyclic voltammetry results indicate that the Pt-decorated CNW/CFP electrode possesses excellent electrocatalytic activity for the reduction of H<inf>2</inf>O<inf>2</inf>. Amperometric responses indicate the high-sensitivity detection capability of the Pt-decorated CNW/CFP electrode for H<inf>2</inf>O<inf>2</inf>.

DOI： 10.7567/JJAP.56.06HF03

Growth of InN films by radical-enhanced metal organic chemical vapor deposition at a low temperature of 200 °C 査読有り

Takai, S; Lu, Y; Oda, O; Takeda, K; Kondo, H; Ishikawa, K; Sekine, M; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 6 ) 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

The InN films were deposited on GaN surfaces at a low temperature of 200 °C by radical-enhanced metal organic chemical vapor deposition (REMOCVD). The REMOCVD system can provide N radicals from the plasma of a N<inf>2</inf>-H<inf>2</inf> mixture gas without using ammonia. Two types of GaN substrate, bulk GaN and GaN on Si(111), were used. The growth mode was modeled as a step flow on the basis of surface morphology observation by atomic force microscopy.

DOI： 10.7567/JJAP.56.06HE08

Electron behaviors in afterglow of synchronized dc-imposed pulsed fluorocarbon-based plasmas 査読有り

Ueyama, T; Fukunaga, Y; Tsutsumi, T; Takeda, K; Kondo, H; Ishikawa, K; Sekine, M; Iwata, M; Ohya, Y; Sugai, H; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 6 ) 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Electron behaviors in a pulsed dual radio frequency (RF) capacitively coupled plasma of a mixture of C<inf>4</inf>F<inf>8</inf>, O<inf>2</inf>, and Ar gases, where the DC bias of %300V in the RF-on period was imposed and synchronously increased to %1000V in the RF-off period, were investigated. The synchronous DC bias prolongs the electron density (n<inf>e</inf>) decay and provides emission of Ar at a wavelength of 750.38nm in early afterglow at 3 μs during the RF-off period of 10 kHz pulse modulation. The rapid n<inf>e</inf> decay occurred with the electron attachments to the electronegative fluorocarbons, and thus the plasma consisting of positive and negative ions was generated. The DC bias voltage seems to be applied between the electrodes and the positive ions accelerated to the top electrode, and enhanced the secondary electron generation at the top electrode surface in the RF-off period with the ion bombardments, concomitantly with the synchronous emissions.

DOI： 10.7567/JJAP.56.06HC03

Progress and prospects in nanoscale dry processes: How can we control atomic layer reactions? 査読有り国際共著 Open Access

Ishikawa, K; Karahashi, K; Ichiki, T; Chang, JP; George, SM; Kessels, WMM; Lee, HJ; Tinck, S; Um, JH; Kinoshita, K

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 6 ) 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

In this review, we discuss the progress of emerging dry processes for nanoscale fabrication. Experts in the fields of plasma processing have contributed to addressing the increasingly challenging demands in achieving atomic-level control of material selectivity and physicochemical reactions involving ion bombardment. The discussion encompasses major challenges shared across the plasma science and technology community. Focus is placed on advances in the development of fabrication technologies for emerging materials, especially metallic and intermetallic compounds and multiferroic, and two-dimensional (2D) materials, as well as state-of-the-art techniques used in nanoscale semiconductor manufacturing with a brief summary of future challenges.

DOI： 10.7567/JJAP.56.06HA02

Selective atomic-level etching using two heating procedures, infrared irradiation and ion bombardment, for next-generation semiconductor device manufacturing 査読有り

Shinoda, K; Miyoshi, N; Kobayashi, H; Miura, M; Kurihara, M; Maeda, K; Negishi, N; Sonoda, Y; Tanaka, M; Yasui, N; Izawa, M; Ishii, Y; Okuma, K; Saldana, T; Manos, J; Ishikawa, K; Hori, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 50 巻 ( 19 ) 2017年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics D Applied Physics

The demand for precisely controlled etching is increasing as semiconductor device geometries continue to shrink. To fulfill this demand, cyclic atomic level/layer etching will become one of the key technologies in semiconductor device manufacturing at nanometer dimensions. This review describes recent trends in semiconductor devices and some of the latest results on cyclic atomic-level etching. In particular, it focuses on two types of cyclic etching that use different heating procedures: infrared irradiation for isotropic etching and Ar<sup>+</sup> ion bombardment for anisotropic etching. It describes how an inductively-coupled-plasma down-flow etching apparatus with infrared lamps can be used for isotropic cyclic etching. The isotropic cyclic etching of SiN involves the formation and thermal desorption of ammonium hexafluorosilicate-based surface modified layers. This method features high selectivity with respect to SiO<inf>2</inf>, atomic-level control of the amount of SiN etching, and isotropic etched features. On the other hand, the anisotropic cyclic etching with Ar<sup>+</sup> ion bombardment uses a microwave electron-cyclotron-resonance plasma etching apparatus. The anisotropic process for poly Si is composed of cyclic repetitions of chlorine adsorption and Ar<sup>+</sup> ion bombardment. The anisotropic process for SiN is composed of cyclic repetitions involving an adsorption step using hydrofluorocarbon chemistry and a desorption step using Ar<sup>+</sup> ion bombardment. Potential applications of these isotropic/anisotropic cyclic etching processes are described.

DOI： 10.1088/1361-6463/aa6874

Spatial distributions of O, N, NO, OH and vacuum ultraviolet light along gas flow direction in an AC-excited atmospheric pressure Ar plasma jet generated in open air 査読有り

Takeda, K; Ishikawa, K; Tanaka, H; Sekine, M; Hori, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 50 巻 ( 19 ) 2017年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics D Applied Physics

Ground-state O (<sup>3</sup>P<inf>j</inf>) and N (<sup>4</sup>S°) atoms, nitric oxide (NO) and hydroxyl (OH) radicals, and vacuum ultraviolet (VUV) radiation emitted from an AC-excited Ar atmospheric pressure plasma jet (APPJ) operated in open air were measured using VUV absorption spectroscopy, laser induced fluorescence spectroscopy and optical emission spectroscopy, respectively. The O (<sup>3</sup>P<inf>j</inf>) density decreased with increasing distance from the plasma head, and the decrease rate in the edge region of the plasma jet around 8 mm distance was especially high. On the other hand, the N (<sup>4</sup>S°) atom density was almost constant up to approximately 10 mm and increased with the distance over 12 mm. The relative NO density increased with the distance up to 10 mm and then became saturated, although the OH density was significantly reduced from the plasma jet exit of the head, and could be observed in the plasma jet only up to the distance of 5 mm. Emissions due to N, H and O atoms were observed in the VUV region and the emission intensity for N atoms (wavelength: 174.3 nm) decreased exponentially with increasing the distance. The results obtained with the Ar APPJ operated in open air conditions indicate the generation of many different reactive oxygen and nitrogen species by gas-phase reactions, and the composition of the reactive species is strongly dependent on the distance from the plasma head. These results are very useful for clarifying the kinetics of reactive species in APPJs and their application in various technological fields.

DOI： 10.1088/1361-6463/aa6555

電子スピン共鳴法を活用したプラズマバイオ反応プロセスの診断招待有り査読有り

石川健治, 近藤隆, 竹田圭吾, 呉準席, 橋爪博司, 田中宏昌, 近藤博基, 太田貴之, 伊藤昌文, 関根誠, 堀勝

プラズマ核融合学会誌 2017年5月

Bactericidal pathway of <i>Escherichia coli</i> in buffered saline treated with oxygen radicals 査読有り

Kobayashi, T; Iwata, N; Oh, JS; Hahizume, H; Ohta, T; Takeda, K; Ishikawa, K; Hori, M; Ito, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 50 巻 ( 15 ) 2017年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics D Applied Physics

Bactericidal effects of phosphate buffered saline treated with electrically neutral oxygen radicals on Escherichia coli (E. coli) are studied using an atmospheric pressure radical source and colony counting method. To clarify the bactericidal mechanism, the chemistry in phosphate buffers treated with oxygen radicals with and without saline has been quantitatively investigated using the well-established chemical reporters N,N-diethyl-p-phenylenediamine reagent and Amplex Red for residual chlorine (HClO and ClO<sup>-</sup>) and hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>), respectively. From the results, we have found that the presence of chlorine in the solutions treated with oxygen radicals is the most important factor in the further chemical reactions to generate hypochlorous acid in E. coli death, and H<inf>2</inf>O<inf>2</inf> is also linked to the bactericidal effect via an indirect chemical pathway.

DOI： 10.1088/1361-6463/aa61d7

Effects of •OH and •NO radicals in the aqueous phase on H<sub>2</sub>O<sub>2</sub> and NO<sub>2</sub><SUP>-</SUP> generated in plasma-activated medium 査読有り

Kurake, N; Tanaka, H; Ishikawa, K; Takeda, K; Hashizume, H; Nakamura, K; Kajiyama, H; Kondo, T; Kikkawa, F; Mizuno, M; Hori, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 50 巻 ( 15 ) 2017年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics D Applied Physics

A plasma-activated medium (PAM), which means a cell-culture medium irradiated with cold atmospheric plasmas or non-equilibrium atmospheric pressure plasma (NEAPP), has shown strong antitumor effects on various kinds of cells such as gastric cancer cells, human lung adenocarcinoma cells, human breast cancer cells and so on. In order to clarify the mechanism, it is extremely important to investigate the behaviors of stable and unstable reactive oxygen nitrogen species in culture medium irradiated by NEAPP. The roles of hydroxyl radicals (•OH) and nitric oxide (•NO) were studied to understand the dominant synthetic pathways of H<inf>2</inf>O<inf>2</inf> and in culture medium irradiated with NEAPP. In the PAM, •OH in the aqueous phase was generated predominantly by photo-dissociation. However, most of the H<inf>2</inf>O<inf>2</inf> nor generated in the PAM did not originate from aqueous •OH and •NO. Pathways for the generation of H<inf>2</inf>O<inf>2</inf> and are suggested based on the high concentrations of intermediates generated at the gas/aqueous-phase interface following NEAPP irradiation. On the basis of these results, the reaction model of chemical species in the culture medium is proposed.

DOI： 10.1088/1361-6463/aa5f1d

Spatial profiles of interelectrode electron density in direct current superposed dual-frequency capacitively coupled plasmas 査読有り Open Access

Ohya, Y; Ishikawa, K; Komuro, T; Yamaguchi, T; Takeda, K; Kondo, H; Sekine, M; Hori, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 50 巻 ( 15 ) 2017年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics D Applied Physics

We present experimentally determined spatial profiles of the interelectrode electron density (n <inf>e</inf>) in dual-frequency capacitively coupled plasmas in which the negative direct current (dc) bias voltage (V <inf>dc</inf>) is superposed; in the experiment, 13 MHz (P <inf>low</inf>) was applied to the lower electrode and 60 MHz (P <inf>high</inf>) to the upper electrode. The bulk n <inf>e</inf> increased substantially with increases in the external power, P <inf>high</inf>, P <inf>low</inf>, and with increases in V <inf>dc</inf>. When P <inf>low</inf> was insufficient, the bulk n <inf>e</inf> decreased as the V <inf>dc</inf> bias increased. The bulk n <inf>e</inf> increased due to its dependence on V <inf>dc</inf>, especially for |V <inf>dc</inf>| > 500 V. This may correspond to the sheath voltages (V <inf>s</inf>) of the lower electrode. The n <inf>e</inf> values in front of the upper electrode were coupled with the V <inf>dc</inf>: the V <inf>dc</inf> dependence first decreased and then increased. The dc currents (I <inf>dc</inf>) of the upper electrode were collected when a large P <inf>low</inf> was applied. The value of I <inf>dc</inf> at the threshold value of V <inf>dc</inf> ≈ V <inf>s</inf> (e.g. -500 V) increased with an increase in n <inf>e</inf>. When |V <inf>dc</inf>| exceeded the threshold, the spatial n <inf>e</inf> profile and the I <inf>dc</inf> dependence were changed relative to the electrical characteristics of the dc superposition; this led to a change in the location of the maximum n <inf>e</inf>, the width of the area of n <inf>e</inf> depletion in front of the electrodes, and a transition in the electron heating modes.

DOI： 10.1088/1361-6463/aa60f7

酸素ラジカル照射された馬肉水抽出液のESR測定査読有り

北田悠人, 石川健治, 堀勝, 伊藤昌文, 林利哉

応用物理学会学術講演会講演予稿集 2017.1 巻 ( 0 ) 頁： 1802 - 1802 2017年3月

マルチプレックスCARSによるプラズマと細胞の相互作用の観察査読有り

古田凌, 堀勝, 関根誠, 石川健治, 太田貴之, 近藤博基, 橋爪博司, 竹田圭吾, 伊藤昌文, 田中宏昌

応用物理学会学術講演会講演予稿集 2017.1 巻 ( 0 ) 頁： 1801 - 1801 2017年3月

Behavior of absolute densities of atomic oxygen in the gas phase near an object surface in an AC-excited atmospheric pressure He plasma jet 査読有り Open Access

Takeda, K; Kumakura, T; Ishikawa, K; Tanaka, H; Sekine, M; Hori, M

APPLIED PHYSICS EXPRESS 10 巻 ( 3 ) 2017年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Express

The quantitative behavior of atomic oxygen in the gas phase near a Cu wire surface in an AC-excited atmospheric pressure He plasma jet in open air was measured using time-resolved vacuum ultraviolet absorption spectroscopy. The atomic oxygen density had a peak at a distance between the plasma source and the Cu wire, and the peak position moved away from the source with an increase in the gas flow rate. The behavior is considered to be dependent on the plasma density and the influence of ambient air. The results are important for supplying atomic oxygen to samples for plasma jet treatment in the atmosphere.

DOI： 10.7567/APEX.10.036201

Characteristics of optical emissions of arc plasma processing for high-rate synthesis of highly crystalline single-walled carbon nanotubes 査読有り

Ando, A; Takeda, K; Ohta, T; Ito, M; Hiramatsu, M; Ishikawa, K; Kondo, H; Sekine, M; Suzuki, T; Inoue, S; Ando, Y; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 3 ) 2017年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Single-walled carbon nanotubes (SWNTs) were synthesized with a high growth rate using an arc plasma employing carbon electrodes with a Ni-Y mixture catalyst. However, the mechanism of growth of highly crystalline SWNTs has not been clarified. Reactions between carbon and catalyst are considered to be one of the crucial factors in SWNT growth. Optical emission spectroscopy (OES) provides the information about the species in the plasma. C2, Ni, and Y emissions in the arc plasma at different currents were measured to investigate the relationship between active species in the arc plasma and the SWNTsynthesis. On the basis of OES results, it was found that the balance between catalytic metal atoms and C2 radical emissions indicated the crystallinity ratio of SWNTs in thin graphitic or amorphous carbon layers. These results are useful for controlling the growth of SWNTs employing arc plasmas.

DOI： 10.7567/JJAP.56.035101

Investigation of effects of ion energies on both plasma-induced damage and surface morphologies and optimization of high-temperature Cl<sub>2</sub> plasma etching of GaN 査読有り

Liu, ZC; Pan, JL; Asano, A; Ishikawa, K; Takeda, K; Kondo, H; Oda, O; Sekine, M; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 2 ) 2017年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

The minimization of plasma-induced damage (PID) in plasma etching is important for the precise and smooth removal of a depth of approximately 7 nm of GaN films to fabricate gate-recess GaN-based normally-off power electronic devices. We have systematically studied the photoluminescence (PL) properties and surface morphologies of GaN films exposed to Cl<inf>2</inf> plasma at 400°C, focusing on their dependences on etch time and ion energy. It is noticeable that PL degradation saturated at etch times of more than 2 min, while surface roughness increased continuously with etch time. Variations of surface roughness with bias voltage were negligible. PID was successfully suppressed by reducing bias voltage, leading to the decrease in incident ion energy on the surface, and thus the near-band-edge emission (NBE) intensity as a PL property was increased to 98.8% of the initial value.

DOI： 10.7567/JJAP.56.026502

Absolute density of precursor SiH<sub>3</sub> radicals and H atoms in H<sub>2</sub>-diluted SiH<sub>4</sub> gas plasma for deposition of microcrystalline silicon films 査読有り Open Access

Abe, Y; Ishikawa, K; Takeda, K; Tsutsumi, T; Fukushima, A; Kondo, H; Sekine, M; Hori, M

APPLIED PHYSICS LETTERS 110 巻 ( 4 ) 2017年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Letters

Microcrystalline hydrogenated silicon films were produced at a high deposition rate of about 2 nm/s by using a capacitively coupled plasma under a practical pressure of around 1 kPa. The SiH<inf>4</inf> source gas was almost fully dissociated when highly diluted with H<inf>2</inf> gas, and the dominant species in the gas phase were found to be SiH<inf>3</inf> radicals, which are film-growth precursors, and H atoms. The absolute density of these species was measured as the partial pressure of SiH<inf>4</inf> gas was varied. With the increasing SiH<inf>4</inf> gas flow rate, the SiH<inf>3</inf> radical density, which was on the order of 10<sup>12</sup> cm<sup>-3</sup>, increased linearly, while the H-atom density remained constant at about 10<sup>12</sup> cm<sup>-3</sup>. The film growth mechanism was described in terms of precursors, based on the measured flux of SiH<inf>3</inf> radicals and H atoms, and the relative fraction of higher-order radicals.

DOI： 10.1063/1.4974821

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