"Sputter Deposition of Single Crystal ZnO Films on 18% Lattice mismatched c-Al2O3 Substrates via Nitrogen Mediated Crystallization" N. Itagaki, K. Kuwahara, I. Suhariadi, K. Oshikawa, K. Matsushima, D. Yamashita, H. Seo, K. Kamataki, G. Uchida, K. Koga, and M. Shiratani

Zinc-Indium Oxynitride Thin Films for Multiple-Quantum–Well Solar Cells
N. Itagaki, K. Matsushima, T. Hirose, K. Kuwahara, D. Yamashita, H. Seo, K. Kamataki, G. Uchida, K. Koga, M. Shiratani

"High Capacity Li Ion Battery Anodes Using Silicon Carbide Nanoparticles Produced by Double Multi-Hollow Discharge Plasma CVD"
K. Kamataki, M. Shiratani, T. Ishihara, H. Nagano, Y. Morita, K. Kuwahara, G. Uchida, H. Seo, N. Itagaki, K. Koga

Interaction between amplitude modulated reactive plasmas and nanoparitcles grown in the plasmas
KUNIHIRO KAMATAKI, KAZUNORI KOGA, GIICHIRO UCHIDA, NAHO ITAGAKI, HYUNWOONG SEO AND MASAHARU SHIRATANI

"Deposition profile control of plasma CVD films on nano-patterned substrates" M. Shiratani, K. Koga

対象論文 “Cluster-suppressed plasma chemical vapor deposition method for high quality hydrgenated amorphous silicon films”, K. Koga, M. Kai, M. Shiratani, Y. Watanabe, and N. Shikatani, Japanese Journal of Applied Physics, Vol.41, pp. L168-170 (2002).

対象講演「クラスタ抑制プラズマCVD装置による高品質a-Si : H作製」
（古閑一憲, 園田剛士,鹿谷昇,白谷正治,渡辺征夫）

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DOI： 10.35848/1882-0786/abd717

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DOI： 10.1002/ppap.202000159

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DOI： 10.1016/j.diamond.2020.108050

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DOI： 10.1016/j.cplett.2020.137920

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DOI： 10.35848/1347-4065/abc3a1

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DOI： 10.1016/j.molstruc.2020.129479

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DOI： 10.35848/1347-4065/abba0c

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DOI： 10.3389/fpls.2020.568924

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DOI： 10.1063/5.0011563

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DOI： 10.35848/1882-0786/ab9712

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Regarding crystalline film growth on large lattice-mismatched substrates, there are two primary modes by which thin films grow on a crystal surface or interface. They are Volmer-Weber (VW: island formation) mode and Stranski-Krastanov (SK: layer-plus-island) mode. Since both growth modes end up in the formation of three-dimensional (3D) islands, fabrication of single crystalline films on lattice-mismatched substrates has been challenging. Here, we demonstrate another growth mode, where a buffer layer consisting of 3D islands initially forms and a relaxed two-dimensional (2D) layer subsequently grows on the buffer layer. This 3D-2D mode transition has been realized using impurities. We observed the 3D-2D mode transition for the case of ZnO film growth on 18%-lattice-mismatched sapphire substrates. First, nano-sized 3D islands grow with the help of nitrogen impurities. Then, the islands coalesce to form a 2D layer after cessation of the nitrogen supply, whereupon an increase in the surface energy may provide a driving force for the coalescence. Finally, the films grow in 2D mode, forming atomically flat terraces. We believe that our findings will offer new opportunities for highquality film growth of a wide variety of materials that have no lattice-matched substrates.

DOI： 10.1038/s41598-020-61596-w

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© 2020 The Japan Society of Applied Physics. Understanding the mechanisms behind plasma-induced liquid flow is important for the transport of reactive species in liquid. In this study, we studied the effects of the surrounding gas compositions of a plasma-jet on the plasma-induced downward liquid flow using particle image velocimetry. Nitrogen (N2) and oxygen (O2) mixtures in different mixing ratios were supplied as surrounding gas around a helium (He) plasma jet at a constant flow rate. The results clearly indicated that O2 in the surrounding gas plays a key role in enhancing the downward flow. Increasing the O2 concentration increased the downward flow in the depth direction. An emission spectroscopy analysis suggested that reactive species related to excited atomic O were considered to be important for inducing downward flows. The relationship between the downward flows and oxidation reactions on a liquid target were discussed to determine the reasons responsible for the driving forces.

DOI： 10.35848/1347-4065/ab71dc

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Recently, cold atmospheric plasma (CAP) treatment on seed germination has emerged as a useful technique to increase agriculture production, although, the mechanism of the cold plasma in seed germination is still under investigation. In this work, we studied the role of pigments in the seed coat of radish sprouts on the electron spin resonance (ESR) signals before and after CAP treatment. Radish sprouts seeds having gray color show enhanced ESR signals after the CAP treatment, whereas, no increased ESR signals were observed for brown color seeds of radish sprouts as compared to their respective control seeds. These results reveal that seeds from the same harvest year having different seed coat colors show different responses to the plasma treatment. Although ESR signal intensity can vary with the harvest year, the change in ESR signal intensity after plasma treatment depends on the seed coat color. Independently on the harvest year (2017 and 2018), CAP increased ESR signals stronger in the grey seeds in comparison to the brown ones. The results indicated that seed coat color may be an important variable for understanding differences in the extent of CAP effects on seeds. (C) 2020 The Japan Society of Applied Physics.

DOI： 10.35848/1347-4065/ab7698

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DOI： 10.7567/1347-4065/ab656c

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DOI： 10.1585/pfr.14.4406141

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DOI： 10.1585/pfr.13.1406082

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DOI： 10.1166/sam.2018.3141

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DOI： 10.1557/adv.2017.178

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DOI： 10.1615/PlasmaMed.2017019137

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DOI： 10.1557/adv.2016.617

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DOI： 10.4028/www.scientific.net/MSF.879.1772

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DOI： 10.1557/adv.2016.41

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DOI： 10.1557/opl.2015.248

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DOI： 10.1557/opl.2014.742

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DOI： 10.1088/1742-6596/518/1/012014

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DOI： 10.7566/JPSCP.1.015078

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DOI： 10.1088/1742-6596/441/1/012029

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DOI： 10.1539/joh.11-0164-OA

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DOI： 10.1002/pssc.201001230

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DOI： 10.1063/1.3653600

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プラズマナノテクノロジーで最重要課題となっている揺らぎの制御に関する現状と将来を展望した論文。

DOI： 10.1109/TENCON.2010.5685920

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DOI： 10.1109/TENCON.2010.5686474

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DOI： 10.1109/TENCON.2010.5686677

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DOI： 10.1109/TENCON.2010.5686679

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DOI： 10.1109/TENCON.2010.5686456

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DOI： 10.1109/TENCON.2010.5686704

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DOI： 10.1109/PVSC.2010.5617205

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DOI： 10.1109/PVSC.2010.5616502

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DOI： 10.1109/PVSC.2010.5616514

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Characterization of Dust Particles Ranging in Size from 1 nm to 10 m Collected in LHD
We collected dust particles ranging in size from 1 nm to 10 µm from the Large Helical Device employing two methods: an ex-situ filtered vacuum collection method and an in-situ dust collection method. The size distribution from 1 nm to 10 µm is well expressed by the Junge distribution. Dust particles are classified into three kinds: small spherical dust particles below 1 µm in size, agglomerates consisting of primary particles of 10 nm, and large dust particles above 1 µm in size and irregular in shape; this suggests three formation mechanisms of dust particles: chemical vapor deposition growth, agglomeration, and peeling from walls. In-situ collection shows that agglomeration between dust particles takes place in main discharges. The primary dust particles in agglomerates are around 10 nm in size, suggesting agglomeration between a negatively charged large agglomerate and a positively charged dust particle 10 nm in size. We have also confirmed the important fact that a large number of dust particles move during vacuum vent. Therefore, the in-situ dust collection method is needed to reveal the generation-time and -processes of dust particles and their deposition position during discharges.

DOI： 10.1585/pfr.4.034

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DOI： 10.1088/1742-6596/100/6/062006

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DOI： 10.1088/1742-6596/100/6/062007

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DOI： 10.1088/1742-6596/100/8/082018

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DOI： 10.1039/B704910B

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DOI： 10.1143/JJAP.44.L1509

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DOI： 10.1143/JJAP.44.L1430

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DOI： 10.1109/TPS.2004.828129

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DOI： 10.1557/PROC-762-A9.5

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

Growth of Clusters in Silane Plasma and Their Relation to Deposition of Thin Films

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1557/PROC-766-E3.8

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DOI： 10.1016/S1369-8001(02)00108-7

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DOI： 10.1088/0963-0252/11/3A/334

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DOI： 10.1351/pac200274030483

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DOI： 10.1557/PROC-664-A5.6

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DOI： 10.1238/Physica.Topical.089a00029

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DOI： 10.1557/PROC-609-A5.6

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DOI： 10.1557/PROC-612-D9.2.1

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DOI： 10.1143/JPSJ.69.1925

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DOI： 10.1143/JPSJ.68.1578

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DOI： 10.1143/JJAP.38.1553

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

DOI： 10.1007/s11090-024-10500-9

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Other Link： https://link.springer.com/article/10.1007/s11090-024-10500-9/fulltext.html

DOI： 10.1007/s11090-024-10500-9

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DOI： 10.1109/TPS.2024.3432879

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Publisher：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers  

DOI： 10.35848/1347-4065/ad5d78

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Publisher：IEEE Sensors Letters  

Nonthermal atmospheric-pressure discharge plasma is considered important for sterilization. Reactive species, such as active oxygen species, radicals, and nitrate ions, generated by the discharge plasma damage the target bacterial cell wall/membrane and DNA. Several plasma sterilization methods have been proposed, including dielectric barrier discharge (DBD). To achieve effective sterilization, it is necessary to evaluate their characteristics using many parameters. This letter aims to demonstrate a proof-of-concept of a novel biological indicator for plasma sterilization. A biological indicator is used to verify sterilization outcomes. We employ DNA-labeled microbeads as biological indicators for the rapid visualization of plasma sterilization. This is based on our recently developed method for visual detection of DNA molecules. If plasma-derived factors cause the degradation of the DNA attached to the microbeads, this can be confirmed by visualization. Herein, we present the correlation between sterilization and visualization in the case of DBD. This method offers a rapid evaluation of plasma sterilization because it easily and quickly determines the sterilization capability of the plasma.

DOI： 10.1109/LSENS.2024.3420437

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

Diluted magnetic semiconductors (DMS) have attracted interest for the potential applications of spintronic devices. The origin of the temperature dependence of their ferromagnetism has been debated and has not been concluded yet. A potential conclusion is that nanoscale inhomogeneity largely affects the temperature dependence of the magnetization in DMS even if the structure and compositions are not largely different. We examined this hypothesis by implementing nitrogen-mediated crystallization consisting of sputtering deposition of amorphous film and solid-phase crystallization by thermal annealing. A series of samples with different inhomogeneities were prepared by changing the annealing time. No significant changes in the composition and the structure were observed after annealing for various times, while significant enhancements were observed in the coercivity, blocking temperature, and grain size. These results provide clear understanding in the temperature dependence of the ferromagnetism in DMS and direct evidence of the potential conclusion on the long-lasting debate. Graphical abstract: (Figure presented.)

DOI： 10.1557/s43580-024-00907-z

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Other Link： https://link.springer.com/article/10.1557/s43580-024-00907-z/fulltext.html

Publisher：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers  

We investigated the effects of tailored voltage waveform (TVW) discharges on the deposition of hydrogenated amorphous carbon (a-C:H) films in CH4/Ar capacitively coupled plasma. TVW discharges employ two driving radio frequencies (13.56 MHz and 27.12 MHz) and control their phase shifts to independently regulate ion bombardment energy (IBE) and ion flux. In this study, a-C:H films were deposited by changing DC-self bias with phase shift and constant applied voltage peak-to-peak. Additionally, we investigated phase-resolved optical emission spectroscopy (PROES) for plasma characterization. As a result, plasma-enhanced CVD (PECVD) for a-C:H films using TVW discharges realize control of film properties such as mass density, sp3 fraction, and H content, while keeping the deposition rate constant. Thus, it is suggested that TVW discharges realize the independent control of IBE and ion flux with high accuracy, highlighting its utility in a-C:H film depositions.

DOI： 10.35848/1347-4065/ad53b0

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

Abstract

Large-scale fabrication of thulium iron garnet (TmIG) films on gadolinium gallium garnet (GGG) substrates, with a total area of 25 cm², has been demonstrated by rotating substrate holders during on-axis sputtering. By optimizing the growth parameters based on the pressure and flow rate of the oxygen ratio, a Tm/Fe ratio of 0.65 was obtained, which is close to the stoichiometry of TmIG. The increase in post-annealing temperature has induced the growth of the TmIG structure by the strain of the lattice constant mechanism. At the highest post-annealing temperature, the crystal structure of TmIG (444) and the perpendicular magnetic anisotropy (PMA) were obtained. This result demonstrates the potential method for large-scale fabrication of TmIG film with PMA.

DOI： 10.35848/1347-4065/ad5aff

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

We have fabricated smooth-surfaced amorphous In2O3:Sn (a-ITO) films at a high temperature of 550 °C, far above the typical crystallization threshold of 150 °C for ITO films. This achievement has been made possible by intentionally introducing N2 into the sputtering atmosphere, which maintains a low N atom incorporation of only a few atomic percent within the films. Positioned within ZONE-T of the Thornton diagram (higher-temperature region characterized by high film density), our method allows the preparation of films with superior film density about 6.96 g/cm3, substantially exceeding the density of 6.58 g/cm3 for conventional a-ITO films fabricated under ZONE-1 (low-temperature region) and approaching the bulk crystal density of In2O3 at 7.12 g/cm3. The films also feature a high carrier density of 5 × 1020 cm−3 and a remarkably low resistivity of 3.5 × 10−4 Ω cm, comparable to those of polycrystalline films. The analysis via vacuum-ultraviolet absorption spectroscopy on N and O atom densities in the plasma suggests that amorphization is primarily caused not by N atoms incorporated in the films but by those temporally adsorbed on the film surface, inhibiting crystal nucleation before eventually desorbing. Our findings will pave the way not only for broader applications of a-ITO films but also for the design of other amorphous materials at temperatures beyond their crystallization points.

DOI： 10.1063/5.0211090

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Publisher：Materials Research Express  

ZnO-AlN pseudo-binary amorphous alloys (a-ZAON hereinafter) with tunable band gaps in the deep ultraviolet (DUV) region have been synthesized using magnetron sputtering. The miscibility gap between ZnO and AlN has been overcome using room-temperature sputtering deposition, leveraging the rapid quenching abilities of sputtered particles to fabricate metastable but single-phase alloys. X-ray diffraction patterns and optical transmittance spectra revealed that the synthesized films with chemical composition ratios of [Zn]/([Zn] + [Al]) = 0.24-0.79 likely manifested as single-phase of a-ZAON films. Despite their amorphous structures, these films presented direct band gaps of 3.4-5.8 eV and thus high optical absorption coefficients (105 cm−1). Notably, the observed values adhered to Vegard’s law for crystalline ZnO-AlN systems, implying that the a-ZAON films were solid solution alloys with atomic-level mixing. Furthermore, atomic force microscopy analyses revealed smooth film surfaces with root-mean-square roughness of 0.8-0.9 nm. Overall, the wide-ranging band gap tunability, high absorption coefficients, amorphous structures, surface smoothness, and low synthesis temperatures of a-ZAON films position them as promising materials for use in DUV optoelectronic devices and power devices fabricated using large-scale glass and flexible substrates.

DOI： 10.1088/2053-1591/ad4f57

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Publisher：Applied Physics Express  

This study reports the response of lettuce seeds undergoing dormancy breaking and early senescence to DBD plasma irradiation. A heat map of germination percentages at 12 h reveals that dormancy has broken at 39 days' storage, and that one minute of plasma irradiation enhances germination in dormant seeds. Plasma irradiation does not affect those seeds where dormancy has already broken. Early senescence via storage was estimated using ESR measurements and the molecular modification of quercetin. This study reveals that lettuce seed susceptibility to plasma irradiation depends on storage duration and conditions, with dormancy state as a critical variable modulating the impact of plasma irradiation.

DOI： 10.35848/1882-0786/ad3798

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Applied Physics Express  

The present study focused on CO2 capture, storage, and conversion through the innovative integration of plasma-ionic liquid (IL) technology. For the first time, we employed plasma-IL technology to confront climate change challenges. We utilized 1-Butyl-3-methylimidazolium chloride IL to capture and store CO2 under atmospheric pressure, and subsequently employed plasma to induce the transformation of IL-captured CO2 into CO. Furthermore, we performed computer simulations to enhance our understanding of the CO2 and CO capture processes of water and IL solutions. This comprehensive approach provides valuable insights into the potential of plasma-IL technology as a viable solution for climate change.

DOI： 10.35848/1882-0786/ad33ea

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Language：English   Publisher：Environmental Science and Pollution Research  

Developing an optimal environmentally friendly bioremediation strategy for petroleum products is of high interest. This study investigated heavy fuel oil (HFO)-contaminated soil (4 and 6 g kg−1) remediation by individual and combined bioaugmentation-assisted phytoremediation with alfalfa (Medicago sativa L.) and with cold plasma (CP)-treated M. sativa. After 14 weeks of remediation, HFO removal efficiency was in the range between 61 and 80% depending on HFO concentration and remediation technique. Natural attenuation had the lowest HFO removal rate. As demonstrated by growth rate and biomass acquisition, M. sativa showed good tolerance to HFO contamination. Cultivation of M. sativa enhanced HFO degradation and soil quality improvement. Bioaugmentation-assisted phytoremediation was up to 18% more efficient in HFO removal through alleviated HFO stress to plants, stimulated plant growth, and biomass acquisition. Cold plasma seed treatment enhanced HFO removal by M. sativa at low HFO contamination and in combination with bioaugmentation it resulted in up to 14% better HFO removal compared to remediation with CP non-treated and non-bioaugmented M. sativa. Our results show that the combination of different remediation techniques is an effective soil rehabilitation strategy to remove HFO and improve soil quality. CP plant seed treatment could be a promising option in soil clean-up and valorization.

DOI： 10.1007/s11356-024-33182-4

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PubMed

Publisher：Plasma  

Plasma-driven science is defined as the artificial control of physical plasma-driven phenomena based on complex interactions between nonequilibrium open systems. Recently, peculiar phenomena related to physical plasma have been discovered in plasma boundary regions, either naturally or artificially. Because laboratory plasma can be produced under nominal conditions around atmospheric pressure and room temperature, phenomena related to the interaction of plasma with liquid solutions and living organisms at the plasma boundaries are emerging. Currently, the relationships between these complex interactions should be solved using science-based data-driven approaches; these approaches require a reliable and comprehensive database of dynamic changes in the chemical networks of elementary reactions. Consequently, the elucidation of the mechanisms governing plasma-driven phenomena and the discovery of the latent actions behind these plasma-driven phenomena will be realized through plasma-driven science.

DOI： 10.3390/plasma7010011

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

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Several studies have documented that treatment by cold atmospheric pressure plasma (CAPP) on plants foster seed germination and growth in recent years. However, the molecular processes that underlie the action of CAPP on the seeds and plants remain mostly enigmatic. We here introduce gemmae of Marchantia polymorpha, a basal liverwort, as a novel model plant material suitable for CAPP research. Treating the gemmae with CAPP for a constant time interval at low power resulted in consistent growth enhancement, while growth inhibition at higher power in a dose-dependent manner. These results distinctly demonstrate that CAPP irradiation can positively and negatively regulate plant growth depending on the plasma intensity of irradiation, offering a suitable experimental system for understanding the molecular mechanisms underlying the action of CAPP in plants.

DOI： 10.1038/s41598-024-53104-1

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Other Link： https://www.nature.com/articles/s41598-024-53104-1

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

In recent years, the chemical reactions with plasma catalysis have been attracted attention. The interaction between plasma ant catalyst can wide the process window, realizing the low pressure and low temperature processes with various catalysts. However, the wide process range make it difficult to optimization for social implement. The key lies in elucidating the reaction mechanism, predicting reactions through numerical simulations, and deriving optimal conditions. On the other hand, recent research has suggested that the use of molecular sieves (MS) can improve methanation efficiency. This can be combined with catalysts, offering new potential applications of MS in chemical reactions. Here, we investigated the more efficient combination of plasma and MS and their reaction mechanisms. As a result, it was found that: 1. The use of MS reduces the oxidation source in the gas phase, leading to an increase in methanation efficiency by suppressing reverse reactions. 2. The adsorption effect of MS, which suppress the reverse reaction, increases with higher pressure. 3. MS in plasma decrease the energy in plasma decrease the energy within the plasma, reducing the CO2 decomposition rate due to electron impact.

DOI： 10.1016/j.rsurfi.2024.100204

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Plasma Processes and Polymers  

The current research focuses on carbon dioxide (CO2) conversion at ambient conditions using streamer plasma. In this study, treatment time and humidity have been found to influence CO2 conversion. Our findings reveal a maximum CO2 conversion rate of 35.2%, achieved with a remarkably high energy efficiency of CO2 conversion at 135% and a low energy cost of 2.17 eV/molecule. We employed optical emission and fourier-transform infrared spectroscopy spectroscopy to analyze the different dissociation products of CO2 and determine the percentage of CO2 conversion. Furthermore, we utilized a two-dimensional (2D) fluid dynamics model and a zero-dimensional (0D) chemistry model to gain insights into the reactor mechanism.

DOI： 10.1002/ppap.202300141

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Smart Processing Society for Materials, Environment & Energy (High Temperature Society of Japan)  

 Carbon dioxide reduction is one of the key technologies for achieving a sustainable society. In this study, plasma catalysis were used to hydrogenate carbon dioxide to produce methane. Plasma catalysis have attracted attention in recent years as a technology promoting a reaction at lower temperatures by various synergistic effects between plasma and catalysts. In this study, molecular sieve with a pore diameter of 3 Å was used as a catalyst and its role was investigated. The results showed that: 1. molecular and atomic adsorption functions of molecular sieves are useful to inhibit reverse reactions; 2. the influence of molecular sieves becomes stronger at higher pressures, resulting in higher methane production; 3. energetic reactive particles derived from hydrogen deactivate molecular sieves; 4. molecules adsorbed on molecular sieve can be recycled by hydrogen plasma irradiation.

DOI： 10.7791/jspmee.13.31

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

Thulium iron garnet, Tm3Fe5O12 with perpendicular magnetic anisotropy is fabricated using an on-axis sputtering technique followed by annealing, whereas previous reports have used unusual off-axis geometries. Stoichiometric Tm3Fe5O12 is obtained after the modification of the deposition conditions involving the position of the substrate relative to the cathode, which affects both the chemical and structural properties. The effective perpendicular magnetic anisotropy of 8.6 kJ/m3 is well in line with the results of previous studies using pulse laser deposition and off-axis sputtering. A maze domain pattern is observed, and the domain-wall energy is evaluated as 0.69 mJ/m2.

DOI： 10.1016/j.tsf.2023.140176

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Language：English   Publisher：Japan Society for Occupational Health  

<p><b>Objectives:</b> We aimed to analyze the subchronic toxicity and tissue distribution of indium after the intratracheal administration of indium-tin oxide nanoparticles (ITO NPs) to the lungs of rats.</p><p><b>Methods:</b> Male Wistar rats were administered a single intratracheal dose of 10 or 20 mg In/kg body weight (BW) of ITO NPs. The control rats received only an intratracheal dose of distilled water. A subset of rats was periodically euthanized throughout the study from 1 to 20 weeks after administration. Indium concentrations in the serum, lungs, mediastinal lymph nodes, kidneys, liver, and spleen as well as pathological changes in the lungs and kidneys were determined. Additionally, the distribution of ionic indium and indium NPs in the kidneys was analyzed using laser ablation-inductively coupled plasma mass spectrometry.</p><p><b>Results:</b> Indium concentrations in the lungs of the 2 ITO NP groups gradually decreased over the 20-week observation period. Conversely, the indium concentrations in the mediastinal lymph nodes of the 2 ITO groups increased and were several hundred times higher than those in the kidneys, spleen, and liver. Pulmonary and renal toxicities were observed histopathologically in both the ITO groups. Both indium NPs and ionic indium were detected in the kidneys, and their distributions were similar to the strong indium signals detected at the sites of inflammatory cell infiltration and tubular epithelial cells.</p><p><b>Conclusions:</b> Our results demonstrate that intratracheal administration of 10 or 20 mg In/kg BW of ITO NPs in male rats produces pulmonary and renal toxicities.</p>

DOI： 10.1093/joccuh/uiae019

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Publisher：Plasma Chemistry and Plasma Processing  

Climate change is considered one of the main challenges in this century, and CO2 emissions significantly cause it. Integrating CO2 capture, storage, and conversion is proposed to solve this problem. 1-Butyl-3-methylimidazolium chloride ([Bmim]Cl) ionic liquid was employed to capture and store CO2 from the air and subsequently converted into CO using non-thermal plasma. Moreover, we also tested the CO2 capture and storage capacity of water from different sources, e.g., Milli-Q, deionized water, and tap water. [Bmim]Cl solution captured CO2 from the air and then converted to CO after 24 h using plasma. In comparison with water (Milli-Q water, deionized water, and tap water), CO production was increased by 28.31% in the presence of water (Milli-Q water, deionized water, and tap water) + [Bmim]Cl. It suggests that this method could be a promising way to capture, store, and convert CO2 from air at atmospheric pressure and room temperature as an effort to reduce carbon emission.

DOI： 10.1007/s11090-024-10500-9

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Scientific Reports  

This study provides the health effects assessment of rice cultivated from plasma-irradiated seeds. The rice (Oryza sativa L.) cultivated from seeds with plasma irradiation showed a growth improvement (slope-ratios of with plasma to without plasma were 1.066, 1.042, and 1.255 for tiller, and earing, and ripening periods, respectively) and an 4% increase in yield. The cultivated rice was used for repeated oral administrations to mice for 4-week period. Distilled water and rice cultivated from seeds without plasma irradiation were also used as control. The weights of the lung, kidney, liver, and spleen, with corresponding average values of 0.22 g, 0.72 g, 2.1 g, and 0.17 g for w/ plasma group and 0.22 g, 0.68 g, 2.16 g, and 0.14 g for w/o plasma group, respectively, showing no effect due to the administration of rice cultivated from plasma-irradiated seeds. Nutritional status, liver function, kidney function, and lipid, neutral fat profiles, and glucose metabolism have no significant difference between with and without plasma groups. These results show no obvious subacute effects were observed on rice grains cultivated and harvested from the mother plant that experienced growth improvement by plasma irradiation. This study provides a new finding that there is no apparent adverse health effect on the grains harvested from the plasma-irradiated seeds.

DOI： 10.1038/s41598-023-43897-y

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Publisher：Japanese Journal of Applied Physics  

Highly selective Si3N4 etching on Si was achieved in a CH3F/O2/Ar plasma using pulsed-microwave plasma and time-modulation bias. The Si3N4/Si selectivity reached infinity at a peak-to-peak voltage (V pp) of 240 V. The effect of pulsed-microwave on CH3F gas dissociation for highly selective Si3N4 etching was investigated by deposited film analysis, optical emission spectroscopy, and ion current flux measurements. As the duty cycle of the pulsed-microwave was decreased, the plasma density during the pulse on period decreased and the CH/H ratio increased. The pulsed-microwave plasma produced low-dissociation radicals by providing a low plasma density. The low-dissociation radicals in the CH3F plasma formed a fluorine (F)-rich hydrofluorocarbon (HFC) layer on the Si3N4 wafer surface. The F-rich HFC layer promotes Si3N4 etching even at low ion energy, where Si etching does not proceed, and enables highly selective Si3N4 etching on Si.

DOI： 10.35848/1347-4065/ace0ca

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Japanese Journal of Applied Physics  

A gas-liquid discharge plasma (GLDP) reactor is used to degrade organic pollutants such as phenol. GLDP contains a 7-pin plate system used to enhance phenol degradation in the presence of various pH, and gas bubbles produced from air, O2, O3, CO2, and Ar gases. Experimental outcomes show the impact of solution pH, as phenol degradation efficiencies of 85%, 90%, 96%, and 98% were obtained for pH of 12, 9, 3, and 1, respectively, after 60 min of treatment. This shows that the optimum pH for phenol degradation lies between 1 and 3. Moreover, we explored the influence of gas bubbles generated using various gases, such as air, O2, O3, CO2, and Ar, on phenol degradation. In the presence of O3 gas bubbles, the rate and degree of phenol degradation were significantly increased compared to gas bubbles produced from other gases (O2, CO2, Ar, and air). The degradation competence of phenol by added oxygen remained higher than argon. The performance of the GLDP system at various pH values and gas bubbles was evaluated using kinetic models. Pseudo-zero, first and second reaction kinetics models were used to examine the degradation of phenol. The rate of degradation at different pH and in the presence of gas bubbles follows pseudo-zero-order kinetics. Our GLDP reactor consumed energy of 127.5 J l-1 for phenol degradation under the influence of air bubbles and pH 5. The outcome of this research can help in the design of new reactors for industrial wastewater treatment.

DOI： 10.35848/1347-4065/acebfb

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Publisher：Journal of Applied Physics  

In this study, we developed a hybrid machine learning technique by combining appropriate classification and regression models to address challenges in producing high-mobility amorphous In2O3:Sn (a-ITO) films, which were fabricated by radio-frequency magnetron sputtering with a nitrogen-mediated amorphization method. To overcome this challenge, this hybrid model that was consisted of a support vector machine as a classification model and a gradient boosting regression tree as a regression model predicted the boundary conditions of crystallinity and experimental conditions with high mobility for a-ITO films. Based on this model, we were able to identify the boundary conditions between amorphous and crystalline crystallinity and thin film deposition conditions that resulted in a-ITO films with 27% higher mobility near the boundary than previous research results. Thus, this prediction model identified key parameters and optimal sputtering conditions necessary for producing high-mobility a-ITO films. The identification of such boundary conditions through machine learning is crucial in the exploration of thin film properties and enables the development of high-throughput experimental designs.

DOI： 10.1063/5.0160228

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Publisher：Japanese Journal of Applied Physics  

The surface passivation of crystalline silicon (c-Si) is studied during growth of hydrogenated amorphous silicon (a-Si:H) by means of plasma-enhanced CVD. The surface passivation is characterized by an in situ method of the photocurrent measurement of c-Si during the growth of an a-Si:H passivation layer at various growth temperatures. The passivation is also characterized by an ex situ method of the carrier lifetime measurement performed at RT in air. According to both the in situ and ex situ characterization results, the surface passivation is optimized around a growth temperate of 200 °C, where the defect reduction and the band offset formation at the a-Si:H/c-Si interface play important roles.

DOI： 10.35848/1347-4065/ace118

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Japanese Journal of Applied Physics  

CO2 methanation is an effective technology for CO2 reduction. Generally, methanation reactions are accelerated using thermal catalysts. However, the temperature control is difficult because CO2 methanation is an exothermic reaction, and the catalyst is deactivated by overheating. Plasma catalysis can solve this problem by driving this reaction at lower temperatures. Therefore, in this study, we investigated the contribution of the active species generated in the plasma to CO2 methanation. We found that the density of active species is linearly related to the power density, and in particular, the CH4 generation rate is determined by the CO-derived active species, not the H-derived active species. Furthermore, with an increase in the catalyst temperature, a new reaction pathway for CH4 production is added. The results of this study contribute to the understanding of the relationship between the active species produced in plasma and CO2 methanation.

DOI： 10.35848/1347-4065/acdad9

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

Single-step fabrication of fibrous Si/Sn composite nanowire anodes by high-pressure He plasma sputtering for high-capacity Li-ion batteries
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To realize high-capacity Si anodes for next-generation Li-ion batteries, Si/Sn nanowires were fabricated in a single-step procedure using He plasma sputtering at a high pressure of 100–500 mTorr without substrate heating. The Si/Sn nanowires consisted of an amorphous Si core and a crystalline Sn shell. Si/Sn composite nanowire films formed a spider-web-like network structure, a rod-like structure, or an aggregated structure of nanowires and nanoparticles depending on the conditions used in the plasma process. Anodes prepared with Si/Sn nanowire films with the spider-web-like network structure and the aggregated structure of nanowires and nanoparticles showed a high Li-storage capacity of 1219 and 977 mAh/g, respectively, for the initial 54 cycles at a C-rate of 0.01, and a capacity of 644 and 580 mAh/g, respectively, after 135 cycles at a C-rate of 0.1. The developed plasma sputtering process enabled us to form a binder-free high-capacity Si/Sn-nanowire anode via a simple single-step procedure.

DOI： 10.1038/s41598-023-41452-3

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

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Plasma irradiation leads not only active species, but also reactive chemical species, ultraviolet light, electric fields, magnetic fields, and shock waves. To date the effects of reactive chemical species have been mainly discussed. To understand the biological effect caused by an electric potential induced with an atmospheric-pressure plasma, the behavior of cell stimulated by electric potential was investigated using HeLa cell. The cell concentration assay revealed that less than 20% of cells inactivated by potential stimulation and the remained cells proliferate afterward. Fluorescent microscopic observation revealed that potential stimulation is appreciable to transport the molecules through membrane. These results show that potential stimulation induces intracellular and extracellular molecular transport, while the stimulation has a low lethal effect. A possible mechanism for this molecular transport by potential stimulation was also shown using numerical simulation based on an equivalent circuit of the experimental system including adhered HeLa cell. The potential formation caused by plasma generation is decisive in the contribution of plasma science to molecular biology and the elucidation of the mechanism underlying a biological response induction by plasma irradiation.

DOI： 10.1038/s41598-023-42976-4

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Other Link： https://www.nature.com/articles/s41598-023-42976-4

Publisher：Materials Science in Semiconductor Processing  

High-quality amorphous silicon nitride (SiNx) thin films were fabricated by the controlled growth of nanoparticles during SiH4+N2 multi-hollow remote plasma chemical vapor deposition (CVD) at low substrate temperature 100 °C. Measurements from quartz crystal microbalances showed that a higher amount of nanoparticle incorporation in the SiNx film corresponded to a higher ratio of N/Si in the film, implying that the nanoparticles were nitrided in the plasma phase. We controlled the size of the nanoparticles by tuning the gas flow ratio of N2/SiH4 and the total gas flow rate. Transmission electron microscopy and energy-dispersive X-ray spectroscopy showed that smaller nanoparticles in the plasma led to a higher ratio of N/Si in the film and a lower hydrogen content. We attribute these results to the low heat capacity and large specific surface area of the nanoparticles, which enabled active chemical reactions on their surface in the plasma.

DOI： 10.1016/j.mssp.2023.107613

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Publisher：Materials Science in Semiconductor Processing  

We experimentally report the control of structural inhomogeneity and magnetic properties of Co-doped ZnO films using nitrogen mediated-crystallization. The ZnO:CoN were grown on a silicon substrate at room temperature by RF-magnetron sputtering using nitrogen and followed by a post-annealing treatment for 3 hours at 400 °C, 600 °C, 800 °C and 1000 °C in the air. This method induces changes in inhomogeneity properties comprised by microstructure and stoichiometry of each film, which are confirmed by X-ray diffraction, thermal desorption, and X-ray fluorescence measurements. The difference in inhomogeneity has led to the transformation in the magnetic properties. Films annealed at 400 °C, which showed the highest inhomogeneity, exhibited superparamagnetic-ferromagnetic properties. In contrast, all the other films exhibited diamagnetic properties. Increasing the post-annealing temperature above 400 °C reduces inhomogeneities indicated by improved grain size, decreased impurities, and lattice parameters and stoichiometry of ZnO:CoN films approached those of pure ZnO. Our present results will contribute to control the inhomogeneity of ZnO:Co films to improve magnetic properties at room temperature.

DOI： 10.1016/j.mssp.2023.107503

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

Abstract

This study aimed to realize in situ resource utilization in deep-space missions. The Sabatier reaction is used to generate CH₄ from CO₂, which accounts for 95% of the Martian atmosphere, and H₂ from H₂O on Mars. In general, thermal catalysis at temperatures above 250 °C drives the process. This high-temperature process, however, causes catalyst deactivation due to overheating. Plasma catalysis drives low-temperature reactions by excitation and decomposition of source gases via electron impact. We investigated the effect of removing H₂O from gas phase in the reaction with Cu and Ni catalysts using molecular sieves in this study. The reverse reaction can be aided by OH radicals derived from H₂O. Therefore, CO₂ conversion increased from 49.4% to 69.1% for Cu catalysts with molecular sieves, and CH₄ selectivity increased from 3.49% to 6.33%. These findings imply that removing H₂O can suppress the reverse reactions.

DOI： 10.35848/1347-4065/ace831

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ace831/pdf

Publishing type：Research paper (scientific journal)   Publisher：Frontiers in Physics  

Colossal research on CO2 and N2 conversion using non-thermal plasma (NTP) technology has been ongoing since many years. The primary focus is on CO and NH3 production through CO2 and N2 conversion, respectively, with high conversion efficiency and low energy consumption with or without catalysts. Although in the present study, we propose that the NTP can assist in converting CO2 and N2 to plant nutrients in the form of plasma-treated/activated water. We used a homemade streamer plasma device and produced plasma-activated water (PAW) using CO2 and N2 feed gas, CO2-activated water (CAW) and N2-activated water (NAW). Later, we used CAW and NAW to treat the radish seeds and evaluate the germination rate, germination percentage, and seeding growth. To understand the chemical changes in PAW after the NTP treatment, we performed a chemical analysis to detect NO2¯, NO3¯, NH4+, and H2O2 along with the PAW pH and temperature shift. Additionally, to understand the other species produced in the gas phase, we simulated chemical reactions using COMSOL Multiphysics® software. Our results show that NOx and NHx species are less produced in CAW than in NAW, but CO2-generated PAW offers a significantly more substantial effect on enhancing the germination rate and seeding growth than NAW. Therefore, we suggested that CO and H2O2 formed during CAW production trigger early germination and growth enhancement. Furthermore, the total plasma reactor energy consumption, NO3¯ and NH4+ selective production percentage, and N2 conversion percentage were calculated. To our best knowledge, this is the first study that uses plasma-assisted CO2 conversion as a nutrient for plant growth.

DOI： 10.3389/fphy.2023.1211166

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Publisher：Japanese Journal of Applied Physics  

The etching characteristics were studied via time-modulation bias (bias pulsing) by varying the pulsing parameters. The etch profiles were verified using polysilicon gate structures with dense and isolated patterns. Ion energy was defined as the peak-to-peak voltage (V pp) controlled by the RF bias power. The durations of the on period and off period (off time) of bias pulsing were adjusted by the pulse frequency and duty cycle. Profile evolution was observed in the variations in V pp and off time. Increasing the ion energy induced vertical profiles of dense patterns and the tapered profiles of isolated patterns. Extending the off time of bias pulsing induced tapered profiles of dense patterns and vertical profiles of isolated patterns. These results indicated that increasing the ion energy and pulse off time simultaneously was the direction to achieve anisotropic etch profiles for both the isolated and dense patterns.

DOI： 10.35848/1347-4065/acc7ab

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Japanese Journal of Applied Physics  

Methanation of CO2 is a key technology to realize a sustainable society. The reactions should be driven at a lower temperatures from the viewpoint of catalyst stability. Methanation with plasma catalysis can drive reactions at lower temperature than thermal catalysis. However, the reaction mechanism is little understood due to the complexity of the interactions. In this study, we investigated the power and pressure dependence of the methanation efficiency when only plasma is used as a fundamental research. We discuss how these parameters change the vibrational temperature and active species density and affect the methanation efficiency using optical emission spectroscopy.

DOI： 10.35848/1347-4065/acc66a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Journal of Applied Physics  

Plasma-driven liquid flows that are generated in bulk liquid by plasma irradiation are one of the key factors in understanding the interaction between plasma and liquid. In this work, the direction of the plasma-driven liquid flow was successfully switched and controlled only by changing the frequency of argon plasma jet generation. The liquid flow could switch in the opposite direction within 3 s after the frequency change. Changes in the emission spectra with frequency have an important effect on the liquid flows, with results from current waveforms indicating that the frequency also changes the characteristics of the plasma jet.

DOI： 10.35848/1347-4065/acde29

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Language：English   Publisher：Plants  

Stevia rebaudiana Bertoni is an economically important source of natural low-calorie sweeteners, steviol glycosides (SGs), with stevioside (Stev) and rebaudioside A (RebA) being the most abundant. Pre-sowing seed treatment with cold plasma (CP) was shown to stimulate SGs biosynthesis/accumulation up to several fold. This study aimed to evaluate the possibility to predict CP-induced biochemical changes in plants from morphometric parameters. Principle component analysis (PCA) was applied to two different sets of data: morphometric parameters versus SGs concentrations and ratio, and morphometric parameters versus other secondary metabolites (total phenolic content (TPC), total flavonoid content (TFC)) and antioxidant activity (AA). Seeds were treated for 2, 5 and 7 min with CP (CP2, CP5 and CP7 groups) before sowing. CP treatment stimulated SGs production. CP5 induced the highest increase of RebA, Stev and RebA+Stev concentrations (2.5-, 1.6-, and 1.8-fold, respectively). CP did not affect TPC, TFC or AA and had a duration-dependent tendency to decrease leaf dry mass and plant height. The correlation analysis of individual plant traits revealed that at least one morphometric parameter negatively correlates with Stev orRebA+Stev concentration after CP treatment.

DOI： 10.3390/plants12081585

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Language：English   Publisher：Genes and Environment  

Background: Non-thermal atmospheric pressure plasma technologies form the core of many scientific advances, including in the electronic, industrial, and biotechnological fields. The use of plasma as a cancer therapy has recently attracted significant attention due to its cancer cell killing activity. Plasma-activated Ringer’s lactate solution (PAL) exhibits such activity. In addition to ROS, PAL contains active compounds or species that cause cancer cell death, but the potential mutagenic risks of PAL have not been studied. Results: PAL has a low pH value and a high concentration of H2O2. H2O2 was removed from PAL using catalase and catalase-treated PAL with a pH of 5.9 retained a killing effect on HeLa cells whereas this effect was not observed if the PAL was adjusted to pH 7.2. Catalase-treated PAL at pH 5.9 had no significant effect on mutation frequency, the expression of γH2AX, or G2 arrest in HeLa cells. Conclusion: PAL contains one or more active compounds or species in addition to H2O2 that have a killing effect on HeLa cells. The compound(s) is active at lower pH conditions and apparently exhibits no genotoxicity. This study suggested that identification of the active compound(s) in PAL could lead to the development of novel anticancer drugs for future cancer therapy.

DOI： 10.1186/s41021-023-00260-x

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

DOI： 10.3389/fphy.2022.1118018

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

The inverted Stranski–Krastanov (SK) mode is useful for heteroepitaxial growth of single-crystalline ZnO films on 18% lattice-mismatched sapphire substrates. We studied the role of nitrogen atoms during fabrication of a three-dimensional island-shaped buffer layer. We found an unprecedented maximum in the substrate temperature dependence of the density of the crystal grains, which facilitated the growth of flat ZnO layers. To reveal the mechanism of the aforementioned maximum, we measured the absolute N atom density in Ar/N2 sputtering plasma [N]plasma by vacuum-ultraviolet absorption spectroscopy. At [N]plasma = 2.2 × 1010 cm−3, we fabricated a ZnO film with a pit-free surface, attributable to the large surface reaction probability and small incorporation ratio of N atoms into the ZnO films. To describe these results, we applied an Ising model. The analytical calculations provide insights for inverted SK mode and clearly reveal the critical effects of the flux densities. Graphical abstract: [Figure not available: see fulltext.]

DOI： 10.1557/s43578-022-00886-7

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Other Link： https://link.springer.com/article/10.1557/s43578-022-00886-7/fulltext.html

Language：English   Publisher：日本環境変異原ゲノム学会  

プラズマ活性化乳酸リンゲル液(PAL)の細胞障害性と遺伝毒性について検討した。pHが低く高濃度のH2O2を含有するPALから、カタラーゼを用いてH2O2を除去した。その結果、PALのpHは5.6以下から5.9に上昇し、これらのカタラーゼ処理したPALではHeLa細胞に対する殺細胞効果が保持されていたが、カタラーゼ処理したPALのpHを7.2に調整すると効果が消失した。だが、カタラーゼ処理したpH5.9のPALには、HeLa細胞における変異頻度やγH2AX発現およびG2期停止に対し有意な作用を観察されなかった。以上より、今回の実験結果から、PALはH2O2以外にもHeLa細胞に対し殺細胞効果をもたらす1種類以上の活性化合物や活性種が含有されていることが明らかにされた。また、これらの物質は低pH条件下で活性化し遺伝毒性は有さないことから、PAL中の活性物質を同定することにより、抗癌剤の新薬開発に繋がることが期待された。

Language：English   Publisher：The Japan Society of Vacuum and Surface Science  

<p>Amorphous carbon (a-C(:H)) thin films have been studied in a wide range of fields as protective films for automotive parts, hard masks for semiconductor device fabrication, and biocompatible films for medical devices due to their excellent characteristics. In particular, mechanical properties (film stress and fracture toughness) related to film delamination are important because they are related to the durability of the films, which in turn are related to film stress and adhesion strength. Recently, we have shown that the introduction of carbon nanoparticles (CNPs) between two layers of a-C:H thin films reduces film stress[1]. In this study, we evaluated other properties of the CNP-inserted sample and examined the effect of CNPs on the mechanical properties of the film toward the practical stage.</p><p>Sandwich structure films were fabricated using a capacitively coupled plasma-enhanced chemical vapor deposition (PECVD) system [1]. Ar and CH4 gases were introduced from the top at 19 sccm and 2.6 sccm, respectively. The thickness of the first and second layers was 154 nm. For the nanoindentation test, a nanoindentation tester (ENT-1100a) was employed and a Berkovich indenter was used.</p><p></p><p>The load-unloading curve by nano-indentation showed a typical curve at 5 mN, and a step in the curve occurred at over 8 mN, and SEM images of the indentation showed that the membrane peeled off in a circular shape when the step occurred. EDS analysis of the peel scar revealed that the peel occurred at the interface between the first and second layers. In addition, the fracture toughness of the film was determined from the SEM images of the delamination traces and the load-unloading curve at the time of step generation, and it decreased with increasing Cp in the region where the film stress was constant for the CNP coverage. These results suggest that CNP coverage has a negative correlation with fracture toughness and that there is an optimum value for improving mechanical properties. Other properties will be discussed in detail in the presentation.</p><p></p><p>[1] S.H. Hwang et al., Jpn. J. Appl. Phys. 59 100906, (2020).</p>

DOI： 10.14886/jvss.2023.0_1ga06

CiNii Research

Publisher：Plasma Medicine  

Seed treatment with non-thermal plasma has seen a tremendous increase in both direct and indirect applications recently. In this review, we examined the effects of direct plasma irradiation, plasma-activated water (PAW), plasma-activated Ringer’s lactate solution, and plasma-treated soil on seeds, resulting in positive, negative, and neutral changes. Furthermore, we will compare the impact of pressure and feed gases on seed germination and seedling growth. Addition-ally, we focused on the types of reactive oxygen and nitrogen species (RONS) and their concentrations produced in the gas and liquid phases, as these play a crucial role in germination percentage and seedling growth. In conclusion, we find that plasma agriculture’s success is contingent on seed morphology, the types and concentrations of reactive species, and specific plasma characteristics.

DOI： 10.1615/PlasmaMed.2023050454

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

We have investigated the effects of amplitude modulation (AM) discharges especially in differences of AM frequency on plasma parameters such as electric field, electron density, electron temperature, ion energy distribution function (IEDF), and ion angular distribution function (IADF) of capacitively coupled AM discharge Ar plasma using a Particle-in-cell/Monte Carlo collision (PIC-MCC) model. The electron density and the kinetic energy of ions incident on the grounded electrode oscillate periodically with the AM frequency. The oscillation amplitude of the electron density in the central plasma region between the electrodes decreases with increasing the AM frequency above 5 kHz. On the other hand, the peak energy of IEDF decreases with increasing the AM frequency above 500 kHz. Thus, the AM frequency is a good tuning knob to control such plasma parameters.

DOI： 10.1557/s43580-022-00417-w

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

(ZnO)X(InN)1-X films have been epitaxially grown on 0.9%-lattice-mismatched ZnO substrates at 450 °C by sputtering. Films fabricated on O-polar substrates exhibit higher crystal quality and smoother surface. The full width at half-maximum of (0002) rocking curve and the root-mean-square roughness (Rq) of a 30-nm-thick film on O-polar surface are 0.21° and 2.71 nm, respectively, whereas those on Zn-polar one are 0.32° and 4.30 nm, respectively. Rq on O-polar surface further decreases to 0.73 nm as the thickness decreases to 10 nm, where we successfully obtained atomically flat single-crystalline films having atomically sharp interface with the substrates. High-resolution transmission electron microscopy revealed the Stranski–Krastanov (layer plus island) growth for O-polar case and just 3D islanding mode growth for Zn-polar one. All the results indicate the much longer migration length of adatoms on O-polar surface during the film growth, enabling adatoms to reach their thermodynamically favored positions even at low substrate temperature. Graphical abstract: [Figure not available: see fulltext.]

DOI： 10.1557/s43578-022-00827-4

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Other Link： https://link.springer.com/article/10.1557/s43578-022-00827-4/fulltext.html

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

Applicability of precise Raman spectral analysis of a-C:H films deposited using a plasma chemical vapor deposition (CVD) method has been discussed based on the sensitivity to initial conditions in peak separation. The spectral analysis offers to deconvolute the spectra into five peaks, while the as-deposited films prepared by plasma CVD is difficult to the five-peak separation. We found the peak position and the peak height ratio of the D-band to the G(+)-band can be employed to discuss the structure of the as-deposited films. We examined the structural difference between the films deposited at the powered electrode and that at grounded electrode. We found graphene nanoribbon-like structures may be formed in the films deposited on the grounded substrate. This result suggests that the substrate position is an important factor to form the graphene nanoribbon-like structure.

DOI： 10.1557/s43580-022-00310-6

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

Abstract

We investigated the effects of amplitude modulated (AM) capacitively coupled Ar discharge plasma on the ion energy distribution function (IEDF) and the ion angular distribution function (IADF) incident on electrodes using the particle-in-cell/Monte Carlo collision model. For AM discharge, the electron density and electron temperature and the kinetic energy and angle of ions incident on the ground electrode change periodically with AM frequency, whereas ones for continuous wave discharge are almost constant. For AM discharge, the plasma had hysteresis characteristics. The peak energy of IEDF varies from 53 to 135 eV and the FWHM of IADF varies from 1.82 to 3.34 degrees for gas pressure 10mTorr, the peak-to-peak input voltage 400 V and AM level of 50%. The variation width of the peak energy of IEDF and FWHM of IADF increases with the AM level. These effects of AM method discharge are more noticeable at lower pressures. Thus, the AM discharge offers a way to control simultaneously IEDF and IADF, which opens a new avenue for plasma processes such as an ALD-like PECVD.

DOI： 10.35848/1347-4065/ac7626

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ac7626/pdf

Publisher：AIP Advances  

We investigate the effects of the amplitude modulation (AM) discharge method on the growth of nanoparticles and the relation between growth of nanoparticles and plasma generation in tetraethylorthosilicate (TEOS)/O2/Ar plasma. The laser-light scattering (LLS) intensity, which is proportional to the density and the sixth power of the size of nanoparticles in the Rayleigh scattering regime, decreases by 18% at an AM level of 10% and by 60% at an AM level of 50%. On the other hand, the ArI emission intensity, which is roughly proportional to plasma density, is higher than that for the continuous wave discharge. Thus, AM discharges suppress growth of nanoparticles in TEOS plasma. We have shown oscillations of the axial electric field Ez with the AM frequency for AM discharge by electric field measurement using an electro-optic probe. We have discussed that these fluctuations of Ez mainly lead to the vertical oscillation of the levitation position of nanoparticles trapped in the plasma sheath boundary region by taking into account the force balance equation in the axial direction on these negatively charged nanoparticles.

DOI： 10.1063/5.0097691

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Language：English   Publisher：AIP Publishing  

CiNii Research

Language：English   Publisher：Antioxidants  

In order to ensure sufficient food resources for a constantly growing human population, new technologies (e.g., cold plasma technologies) are being developed for increasing the germination and seedling growth without negative effects on the environment. Pinaceae species are considered a natural source of antioxidant compounds and are valued for their pharmaceutical and nutraceutical properties. In this study, the seeds of seven different Norway spruce half-sib families were processed for one or two minutes with cold plasma (CP) using dielectric barrier discharge (DBD) plasma equipment. At the end of the second vegetation season, the total flavonoid content (TFC), DPPH (2,2- diphenyl-1-picryl-hydrazyl-hydrate), and ABTS (2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) antioxidant activity, and the amounts of six organic acids (folic, malic, citric, oxalic, succinic, and ascorbic) were determined in the needles of different half-sib families of Norway spruce seedlings. The results show that the TFC, antioxidant activity, and amounts of organic acids in the seedling needles depended on both the treatment duration and the genetic family. The strongest positive effect on the TFC was determined in the seedlings of the 477, 599, and 541 half-sib families after seed treatment with CP for 1 min (CP1). The TFC in these families increased from 118.06 mg g−1 to 312.6 mg g−1 compared to the control. Moreover, seed treatment with CP1 resulted in the strongest increase in the antioxidant activity of the needles of the 541 half-sib family seedlings; the antioxidant activity, determined by DPPH and ABTS tests, increased by 30 and 23%, respectively, compared to the control. The obtained results indicate that the CP effect on the amount of organic acids in the needles was dependent on the half-sib family. It was determined that treatment with CP1 increased the amount of five organic acids in the needles of the 541 half-sib family seedlings. The presented results show future possibilities for using cold plasma seed treatment in the food and pharmacy industries.

DOI： 10.3390/antiox11081558

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

Abstract

Discharge plasma irradiates seeds with reactive oxygen and nitrogen species (RONS). However, RONS introduced in seeds by plasma irradiation have not been successfully detected thus far. This study provides experimental evidence that nitrate ion NO₃⁻ is introduced in lettuce seeds as RONS upon irradiation with atmospheric-pressure air dielectric barrier discharge plasma. Plasma irradiation for 5 min promotes seed germination. The components of the plasma-irradiated seeds were examined using electrospray ionization quantum mass spectrometry (ESI QMS), which revealed that the plasma irradiation introduced an ion with a mass of 62 m/z in detectable amounts. This ion was identified as NO₃⁻ by liquid chromatography (LC), multiple wavelength detector (MWD), and LC-ESI QMS. A one-dimensional simulation at electron temperature T_e = 1 eV, electron density N_e = 10¹³/m³, and gas temperature T_g = 300 K indicated the introduction of NO₃⁻, involving nitric oxide NO. NO₃⁻ is one of the most important ions that trigger signal transduction for germination when introduced in seeds. The scanning electron microscopy (SEM) images revealed that there was no change on the surface of the seeds after plasma irradiation. Plasma irradiation is an effective method of introducing NO₃⁻ in seeds in a dry process without causing damage.

DOI： 10.1038/s41598-022-16641-1

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Other Link： https://www.nature.com/articles/s41598-022-16641-1

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

Recently, non-thermal plasma technology has been frequently used for wastewater treatment. Plasma technology uses the effect of high-energy electrons, reactive species, ultraviolet light, free radicals, and pyrolysis to treat wastewater. Although in many cases, only the use of non-thermal plasma alone is not successful in degrading the complex organic wastes. This might be because of complexity in wastewater or not appropriate plasma device for wastewater treatment, or improper use of plasma-generated species that plays a critical role in organic waste degradation. To increase the degradation efficiency and reduce treatment time, the combination of non-thermal plasma and catalysts (homogeneous and heterogeneous) improves pollutant removal. This review includes the different non-thermal plasma systems and their action on decolorizing or degradation of dyes, degradation of phenolic pollutants, and degradation of pharmaceutical products, including antibiotics and other volatile organic solvents (VOC’s) with and without catalyst. Finally, probable mechanisms and suggestions to improve the wastewater treatment using non-thermal plasma were put forward. This review aims to help researchers understand the role of treatment time, feed gases, and catalysts on the degradation of organic wastes and looks forward to all possible developments in this field.

DOI： 10.1007/s41614-022-00077-1

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Other Link： https://link.springer.com/article/10.1007/s41614-022-00077-1/fulltext.html

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

We investigated the Ar mixture ratio dependence of the high-energy electron behaviors in capacitively coupled Ar+Ne plasmas using Optical Emission Spectroscopy (OES) and Phase-Resolved Optical Emission Spectroscopy (PROES) methods. OES measurements showed that optical emission intensities of Ar and Ne decreased as Ar mixture ratio increased, which implied decreases in the excitation rates of Ar and Ne. The spatio-temporal distribution of the Ar I 2p1 excitation rate was measured using the PROES method. These measurements showed the Ar I 2p1 excitation rate decreased as the Ar mixture ratio increased, which was consistent with the OES results. These results implied that the collision frequency between electrons and neutral particles increased with increase in Ar mixture ratio. In addition, the sheath expansion width in one RF cycle became small with increasing Ar mixture ratio, which led to a weakening of the effect of stochastic heating and a decrease of the electron temperature.

DOI： 10.1557/s43580-022-00306-2

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Other Link： https://link.springer.com/article/10.1557/s43580-022-00306-2/fulltext.html

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

Heteroepitaxial growth of single-crystalline zinc oxide (ZnO) films on a c-plane sapphire substrate is an important technology for electronics and optoelectronic devices. Recently, the inverted Stranski-Krastanov (SK) mode has been demonstrated, and it has realized the heteroepitaxial growth of ZnO films on a sapphire substrate by sputtering. In this mode, a 10 nm-thick buffer layer consisting of three-dimensional islands (3D buffer layers) initially forms and relaxes the strain, and then, a two-dimensional ZnO film (2D layer) grows involving small strain. To clarify the correlation between the structural properties of the 3D buffer layers and the 2D layer, we introduce a figure of merit (FOM) of ZnO films: the reciprocal of the product of the full width at half-maximum (FWHM) of the (002) and (101) planes of X-ray rocking curves (XRCs) and root-mean-square (RMS) roughness. We find that the FOM of the 2D layers correlates with the RMS roughness, the in-plane orientation, and the lateral correlation length ζ of the surfaces of the buffer layers. We observe a surprisingly high correlation coefficient of 0.97. Our results imply that on the buffer layers with larger ζ, adatoms more easily reach the thermodynamically favored lattice positions. Thus, high-quality single-crystalline ZnO films, where the (002) plane XRC-FWHM and the RMS roughness are 0.05° and 1.5 nm, respectively, are grown on the buffer layers with a large ζ of 13.7 nm. This finding provides a useful tool for understanding the mechanism of the inverted SK mode.

DOI： 10.1021/acs.cgd.2c00145

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：MRS Advances  

Abstract: Dye-sensitized solar cell (DSSC) has low power output and efficiency. Even though the low-concentrated light can increase the POUT and power conversion efficiency (PCE) of DSSC, the effect of increase in the cell temperature, particularly electrolyte evaporation, becomes a major concern. In this study, we compared and investigated the performance of acetonitrile (AN-50), propionitrile (PN-50), and 3-metoxy propionitrile (Z-100) as nitrile-based electrolyte under low-concentrated light. The results showed 4–8 times increase in JSC and POUT in all electrolytes. AN-50 demonstrated an improved performance under influence of 2 cm distance concave mirror concentrated light with the highest JSC = 74.21 mA/cm2, POUT = 24.53 mW/cm2, and η = 7.99%. However, the performance of cell with AN-50 and PN-50 started to degrade within 3 h of measurement. In contrast, Z-100 displayed performance stability during 4 days measurement even with the lowest JSC= 49.98 mA/cm2, POUT = 19.50 mW/cm2, and η = 6.35%. Graphical abstract: [Figure not available: see fulltext.]

DOI： 10.1557/s43580-022-00270-x

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

We have succeeded in epitaxial growth of high-quality Zn1−xMgxO films of x = 0.04–0.33 on 18%-lattice mismatched sapphire substrates using magnetron sputtering. The films have grown in inverted Stranski-Krastanov (inverted SK) mode, where a buffer layer consisting of three-dimensional islands initially forms and a relaxed two-dimensional layer subsequently grows on the buffer layer. The resultant films have flat surfaces with root-mean-square roughness of 0.43–0.75 nm and are of high-crystal qualities even for large Mg contents; the full widths at half maximum of (0002) x-ray rocking curves are 0.05° (x = 0.33) and 0.07° (x = 0.14). Furthermore, we observed that the optical absorption edge shifts continuously toward the shorter wavelength with increasing x, and the band gap has been tuned from 3.5 to 4.3 eV. These results show that the inverted SK mode is useful for fabricating high-quality Zn1−xMgxO films with wide-range tunability of band gaps. Graphical abstract: [Figure not available: see fulltext.]

DOI： 10.1557/s43580-022-00234-1

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Other Link： https://link.springer.com/article/10.1557/s43580-022-00234-1/fulltext.html

Language：Others   Publisher：Agronomy  

To meet the needs of the hungry population, it is critical to boost agricultural product production while minimizing contaminated waste. The use of two nonthermal technologies, pulsed electric field (PEF) and nonthermal plasma (NTP), is increasing every day. As both PEF and NTP are relatively newer areas, there is limited knowledge about these two technologies and their modes of action. Studies showed that PEF treatment on the plant seeds helps germination and seedling growth. The positive impact of PEF intensity is highly dependent on the seed coat type and plant species. Another nonthermal technology, NTP, affects seed germination, seedling growth, yield, and resilience to abiotic stress when generated at varying pressures with and without different feed gases. Early germination, germination rate, and germination percentage were all improved when the seedlings were treated with NTP. Similarly to the PEF treatment, NTP had a negative or no effect on germination. This review examined the effects of PEF and NTP on seed germination and ana-lyzed the situation and mechanism behind the positive or negative effect. Deactivation of proteins and enzymes to extend the shelf life of beverages is another prominent application of PEF and NTP. The interaction of PEF and NTP with proteins aids in understanding the microscopic mechanism of these technologies. Therefore, we covered in this review the potential structural and functional changes in proteins/enzymes as a result of PEF and NTP, as well as a comparison of the benefits and drawbacks of these two technologies.

DOI： 10.3390/agronomy12020482

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Journal of Applied Physics  

CO2 methanation can be a key technology for realizing a sustainable society. CH4 is used as an energy carrier and raw material for chemical products, thereby contributing to the reduction of CO2 emissions. Methanation with plasma catalysis lowers the process temperature, which can improve the throughput and stability. In this study, we investigated the effect of the gas flow rate and the discharge volume on CO2 methanation, using a low-pressure capacitively coupled plasma reactor. Higher gas flow rates can increase the rate of CO2 throughput, but the CH4 selectivity decreases owing to the reduced transportation rate of the reactants to the catalyst surface. Increasing the discharge volume is effective in improving the transportation rate. This study suggested that the structure of the reactor significantly affects the CH4 generation rate.

DOI： 10.35848/1347-4065/ac4822

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Optical Materials  

Upconversion materials (UC) can convert low-energy photons into visible light and, therefore, can be incorporated in solar cells to increase the absorption of visible light. This study synthesized UC nanophosphors Yb3+, Er3+: Y2O3 and Yb3+, Er3+, Zn2+: Y2O3 by a simple co-precipitation method for application in dye-sensitized solar cells (DSSCs). The impact of the enhancement in the concentration of Zn2+ on the photoluminescence (PL) and color point of the synthesized nanophosphors was also investigated. The synthesized nanophosphors emitted intense red and weaker green emissions upon excitation at 980 nm. The incorporation of Zn2+ to the Yb3+, Er3+: Y2O3 nanophosphors leads to color tunability in the red and yellow regions. Furthermore, the synthesized nanophosphors were incorporated into the DSSC photoanode to form a TiO2-UC-based DSSC for converting near-infrared (NIR) into visible light. We observed that the TiO2-UC-based DSSC showed an enhancement ratio in current density and power conversion efficiency of 17.4% and 16.6%, respectively, compared to the bare TiO2-based DSSC. These results reveal that UC-based Yb3+, Er3+, Zn2+: Y2O3 nanophosphors are useful in improving the efficiency of DSSCs and in color tunability applications.

DOI： 10.1016/j.optmat.2021.111928

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<title>Abstract</title>
Nitrogen is a very common element, comprising approximately 78% of Earth’s atmosphere, and is an important component of various electronic devices while also being essential for life. However, it is challenging to directly utilize dinitrogen because of the highly stable triple bond in this molecule. The present review examines the use of non-equilibrium plasmas to generate controlled electron impacts as a means of generating reactive nitrogen species (RNS) with high internal energy values and extremely short lifetimes. These species include ground state nitrogen atoms, excited nitrogen atoms, etc. RNS can subsequently react with oxygen and/or hydrogen to generate new highly reactive compounds and can also be used to control various cell functions and create new functional materials. Herein, plasma-processing methods intended to provide RNS serving as short-lived precursors for a range of applications are examined in detail.

DOI： 10.35848/1347-4065/ac25dc

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ac25dc/pdf

Publishing type：Research paper (scientific journal)   Publisher：IEEE Open Journal of Nanotechnology  

Plasma nanotechnology is widely used for nanoscale etching, dopant implantation and thin-film deposition for state-of-the-art semiconductor devices. Such a plasma nanotechnology has another interesting aspect of synthesizing nanoparticles, in a controlled manner of atomic composition, structure and those size. Here, we present the polymerization and growth of silicon nanoparticles from a molecular level to 10 nm-particles in hydrogen diluted silane plasmas. The polymerization and growth are experimentally studied using various plasma diagnostic tools. The results indicate that nanoparticles are rapidly formed via gas-phase reactions in a low-density plasma comprising high-energy electrons. The growth kinetics and the modification of plasma properties are discussed in terms of gas-phase reactions, charging and coagulation of nanoparticles.

DOI： 10.1109/OJNANO.2022.3209995

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Publisher：2022 International Conference on Informatics Electrical and Electronics, ICIEE 2022 - Proceedings  

Ferromagnetic semiconductor has attracted much attention for the application of spintronic devices, which will bring next generation of the information technology. Cobalt-doped Zinc Oxides (ZnO: Co) is strong candidate of this material group. The ZnO: Co films were grown on a silicon substrate (100) at room temperature by radio-frequency (rf) sputtering deposition and followed by post-Annealing treatment for 3 hours at 400°C and 800°C in the air. The transition from paramagnetic to ferromagnetic occurs after annealing at 400°C, and the properties return to paramagnetic like as-deposition when the temperature rises to 800°C. The XRD measurement of ZnO: Co films exhibited a wurtzite structure in the (002) plane and was free from secondary phases. Then, post-Annealing at 400°C due to shift peak and decrease oxygen element, meanwhile the crystallinity significantly up to 800°C.

DOI： 10.1109/ICIEE55596.2022.10010108

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Publisher：Proceedings of Technical Papers - International Microsystems, Packaging, Assembly, and Circuits Technology Conference, IMPACT  

EUV lithography drives the miniaturization of semiconductors for higher integration, and semiconductor manufacturing is in transition from two-dimensional (2D) to three-dimensional (3D) structures [1], which plays a crucial role in supporting packaging for edge computing such as Internet-of-Things (loT). 3D power scaling enables higher integration without reducing the size of transistors by arranging them vertically instead of horizontally. One of the important processes in manufacturing 3D structured semiconductors is the formation of films on sidewalls of trenches and holes. Such films are often deposited by plasma enhanced chemical vapor deposition (PECVD) [2]. Due to the gas decomposition by plasma, PECVD method archives a high deposition rate of good quality films at low temperature, which is an advantage over other deposition methods such as atomic layer deposition (ALD) [3]. However, this does not fully meet the actual manufacturing requirements. For instance, SiO2 dielectric films deposited by PECVD usually have low coverage and poor film quality on sidewall of trenches and holes compared to films on surface. Ion impact is one of the most important factors contributing to improving step coverage and film quality in trenches and holes. One parameter that characterized ion impact is the ion energy distribution function (IEDF) and ion angular distribution (IADF) [4], [5]. There are strong needs for low temperature deposition in trenches and holes.

DOI： 10.1109/IMPACT56280.2022.9966682

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Dye-sensitized solar cells (DSSCs) are attractive due to their simple fabrication process, low cost, performance stability, and eco-friendly characteristics. The power output (Pout) can be improved by applying an external concentrator, but this is rarely applied because of increasing temperature. Here, we successfully increased the Pout of bifacial DSSCs with the V-shaped plane, and concave mirrors showed an improved power output (Pout: 6.42 and 24.31 mW/cm2, separately) compared to ones without mirrors (4.25 mW/cm2). The high surface temperature on the concave mirror can be reduced with 1 cm mirror distancing followed by a reduction in Pout (19.07 mW/cm2).

DOI： 10.1021/acsaem.1c02774

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

The use of low-temperature plasma for the pre-sowing seed treatment is still in the early stage of research; thus, numerous factors affecting germination percentage, seedling growth, and yield remains unknown. This study aimed to estimate how two critical factors, such as harvest year and seed coat color, affect the percentage of germination and seedling growth after plasma treatment. Radish seeds stored for 2 and 1 year after harvesting (harvested in 2017 and 2018) were sorted into two colors (brown and grey) to investigate the plasma effect on harvest year and seed coat color. We analyzed the amounts of seed phytohormones and antioxidant (γ-tocopherol) were analyzed using mass spectrometry, and physical changes were studied using SEM, EDX, and EPR to understand the mechanism of plasma-induced changes in radish seeds. The obtained results revealed that plasma treatment on seeds affects the germination kinetics, and the maximal germination percentage depends on seed color and the time of seed storage after harvest. Through this study, for the first time, we demonstrated that physical and chemical changes in radish seeds after plasma treatment depends upon the seed color and harvest year. Positive effects of plasma treatment on growth are stronger for sprouts from seeds harvested in 2017 than in 2018. The plasma treatment effect on the sprouts germinated from grey seeds effect was stronger than sprouts from brown radish seeds. The amounts of gibberellin A3 and abscisic acid in control seeds strongly depended on the seed color, and plasma induced changes were better in grey seeds harvested in 2017. Therefore, this study reveals that Air scalar-DBD plasma's reactive oxygen and nitrogen species (RONS) can efficiently accelerate germination and growth in older seeds.

DOI： 10.1038/s41598-021-81175-x

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

The study of protein–protein interactions is of great interest. Several early studies focused on the murine double minute 2 (Mdm2)–tumor suppressor protein p53 interactions. However, the effect of plasma treatment on Mdm2 and p53 is still absent from the literature. This study investigated the structural changes in Mdm2, p53, and the Mdm2–p53 complex before and after possible plasma oxidation through molecular dynamic (MD) simulations. MD calculation revealed that the oxidized Mdm2 bounded or unbounded showed high flexibility that might increase the availability of tumor suppressor protein p53 in plasma-treated cells. This study provides insight into Mdm2 and p53 for a better understanding of plasma oncology.

DOI： 10.3390/ijms22179585

Language：English  

DOI： 10.1016/j.tsf.2021.138701

Language：Others  

In recent years, cold atmospheric pressure plasma (CAP) applications in agriculture are rapidly increasing. This review covers the effect of CAP and plasma-treated liquid (PTL) on seeds. CAP treatment on seed alters the germination percentage, morphology (shoot height, root length, surface area, etc.), gene expression, and biochemical responses (changes in hormones, antioxidants, amino acids, total soluble sugar content, chlorophyll content, etc.). The changes were incorporated in yield-related parameters (fresh and dry weight of seedlings) and water absorption capacity after plasma treatment. Lastly, we discussed the current status of CAP and PTL use in agricultural land.

DOI： 10.35848/1347-4065/abe47d

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Triton X-100, DMSO and TiO2 were blended with PEDOT:PSS to produce a PEDOT:PSS/DMSO/TX100/TiO2 CE. A bifacial DSSC based on the PEDOT:PSS/DMSO/TX100/TiO2 CE was fabricated, and its photovoltaic characteristics were obtained under simulated solar light of 100 mWcm−2. Under bifacial illumination, the DSSC with the Pt CE achieved a current density (Jsc) of 16.16 mAcm−2 and system efficiency (Esys) of 8.67&#37; while the DSSC with the PEDOT:PSS/DMSO/TX100/TiO2 CE achieved a Jsc of 17.72 mAcm−2 and a Esys of 9.14&#37;. PEDOT:PSS/DMSO/TX100/TiO2 CE is very stable, has a high transmittance, exhibits high electro-catalytic activity, and is an excellent substitute for the Pt CE.

DOI： 10.1016/j.cplett.2021.138369

Language：Others  

DOI： 10.1021/acsagscitech.0c00070

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

The recent outbreak of a novel coronavirus (SARS-CoV-2) has caused substantial public health issues worldwide. Cold atmospheric plasma (CAP) has shown its potential application in sterilization. It would be interesting to check the possible effect of CAP on the structure of the C-terminal domain of SARS-CoV-2 (SARS-CoV-2-CTD) spike protein and the interaction SARS-CoV-2-CTD with human angiotensin-converting enzyme 2 (hACE2). Therefore, we performed molecular dynamics simulations to calculate the root-mean-square deviation, root-mean-square fluctuation, principal component analysis and solvent-accessible surface area of SARS-CoV-2-CTD and the SARS-CoV-2-CTD/hACE2 complex with and without possible oxidation.

DOI： 10.35848/1882-0786/abd717

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DOI： 10.35848/1347-4065/abba0c

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

As the application of nanotechnology increases continuously, the need for controlled size nanoparticles also increases. Therefore, in this work, we discussed the growth mechanism of carbon nanoparticles generated in Ar+CH4 multi-hollow discharge plasmas. Using the plasmas, we succeeded in continuous generation of hydrogenated amorphous carbon nanoparticles with controlled size (25–220 nm) by the gas flow. Among the nanoparticle growth processes in plasmas, we confirmed the deposition of carbon-related radicals was the dominant process for the method. The size of nanoparticles was proportional to the gas residence time in holes of the discharge electrode. The radical deposition developed the nucleated nanoparticles during their transport in discharges, and the time of flight in discharges controlled the size of nanoparticles.

DOI： 10.3390/pr9010002

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DOI： 10.35848/1347-4065/abc3a1

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DOI： 10.35848/1347-4065/abbb20

Language：Others  

© 2020 by the authors. In recent years, non-thermal plasma (NTP) application in agriculture is rapidly increasing. Many published articles and reviews in the literature are focus on the post-harvest use of plasma in agriculture. However, the pre-harvest application of plasma still in its early stage. Therefore, in this review, we covered the effect of NTP and plasma-treated water (PTW) on seed germination and growth enhancement. Further, we will discuss the change in biochemical analysis, e.g., the variation in phytohormones, phytochemicals, and antioxidant levels of seeds after treatment with NTP and PTW. Lastly, we will address the possibility of using plasma in the actual agriculture field and prospects of this technology.

DOI： 10.3390/PR8081002

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

© 2020 Elsevier B.V. Understanding the folding and stability of membrane proteins is of great importance in protein science. Recently, osmolytes and ionic liquids (ILs) are increasingly being used as drug delivery systems in the biopharmaceutical industry. However, the stability of membrane proteins in the presence of osmolytes and ILs is not yet fully understood. Besides, the effect of oxidative stress on membrane proteins with osmolytes or ILs has not been investigated. Therefore, we studied the influence of osmolytes and ILs as co-solvents on the stability of a model membrane protein (i.e., Bacteriorhodopsin in purple membrane of Halobacterium salinarum), using UV–Vis spectroscopy and molecular dynamics (MD) simulations. The MD simulations allowed us to determine the flexibility and solvent accessible surface area (SASA) of Bacteriorhodopsin protein in the presence and/or absence of co-solvents, as well as to carry out principal component analysis (PCA) to identify the most important movements in this protein. In addition, by means of UV–Vis spectroscopy we studied the effect of oxidative stress generated by cold atmospheric plasma on the stability of Bacteriorhodopsin in the presence and/or absence of co-solvents. This study is important for a better understanding of the stability of proteins in the presence of oxidative stress.

DOI： 10.1016/j.ijbiomac.2020.01.179

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Copyright © 2017 John Wiley & Sons, Ltd. Organic/inorganic hybrid solar cells have attracted much attention with simple fabrication and high performance because the combination of organic and inorganic materials compensates their disadvantages each other. This work tried to realize highly efficient hybrid solar cell based on crystalline Si and poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) junction. Performance dependences on the resistivity of Si substrate and the thickness of PEDOT:PSS layers were analyzed. Photocurrent of hybrid solar cells strongly depended on Si substrate, while overall performance depended on total resistance of hybrid solar cells not Si substrate. The charge transfer of PEDOT:PSS layer was varied by its thickness, and the 30-nm-thick PEDOT:PSS layer showed the best characteristics of charge transfer. The conductivity of the PEDOT:PSS layer was finally improved by solvent treatment using acetonitrile. As a result, the photovoltaic performance was much enhanced, and it was defined by 0.56 V of VOC, 30.24 mA/cm2 of JSC, 0.68 of FF, and 11.52&#37; of efficiency.

DOI： 10.1002/pip.2961

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© 2019 Korean Physical Society We investigated the effect of hydrogen dilution on the Si cluster volume fraction of hydrogenated amorphous films by varying the hydrogen dilution ratio at 0.5 Torr and compared it to that obtained at pure silane discharge at 0.3, 0.4, and 0.5 Torr. The correlation between the plasma emission characteristic, deposition rate, and cluster volume fraction in the hydrogen dilution plasma was described. The cluster volume fractions of films under hydrogen dilution conditions were similar to those of the pure silane but showed a higher deposition rate. The results suggest that under hydrogen dilution conditions, it is possible to maintain a higher deposition rate with a lower cluster incorporation rate.

DOI： 10.1016/j.cap.2019.11.001

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

Local supply of reactive oxygen species into a tissue model by atmospheric-pressure plasma-jet exposure
© 2019 Author(s). The supply of reactive oxygen species (ROSs) into a tissue by plasmas must be controlled for the safe and effective use of plasma technologies in biomedical applications. In this study, the two-dimensional distributions of ROSs after passing through an agarose tissue model by the plasma-jet exposures were visualized using a KI-starch gel reagent to evaluate the local ROS supply. Partial ROS supply on the tissue model surface induced the local ROS supply in a pointlike shape just under the plasma-exposed spot. The O3-containing gas exposure without direct plasma contact could not induce the local ROS supply. Therefore, the local ROS supply was assumed to be induced by plasma-specific effects. However, the results also indicated that the plasma jet coming in direct contact with the tissue model surface did not necessarily induce the local ROS supply. The effects of the tissue model thickness on the local ROS supply were also studied; the local ROS supply could penetrate to a depth of 2 mm in the tissue model under the given experimental conditions.

DOI： 10.1063/1.5091740

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

DOI： 10.7567/1347-4065/ab1473

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

DOI： 10.7567/1347-4065/ab163b

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

Progress and perspectives in dry processes for nanoscale feature fabrication: toward intelligent processes and virtual product development

Language：Japanese  

Language：Others  

Spatial correlation between density fluctuations of high energy electrons and nanoparticles in amplitude modulated capactively coupled plasma

Language：Others  

Room-temperature fabrication of amorphous In2O3:Sn films with high electron mobility via nitrogen mediated amorphization

Language：Others  

Effects of nitrogen impurity on zno crystal growth on Si substrates
Effects of nitrogen impurity on ZnO crystal growth on Si substrates have been investigated. The quantitative analysis on the surface morphology deriving height-height correlation function indicates that adsorbed nitrogen atoms suppress the secondary nucleation and enhance adatom migration. The resultant films have smooth surface as well as large grain size up to 24 nm even for small thickness of 10 nm. ZnO films fabricated by using such films as buffer layers possess high crystal quality, where the full width at half maximum of (002) rocking curve is 0.68°, one-fourth of that for films fabricated without nitrogen.

DOI： 10.1557/adv.2019.28

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Sputter Epitaxy of (ZnO)x(InN)1-x films on Lattice-mismatched Sapphire Substrate
We have recently developed a novel semiconductor, (ZnO)x(InN)1-x (abbreviated to ZION). In this study, we have succeeded in direct epitaxial growth of ZION films on 19?21&#37;-lattice-mismatched c-plane sapphire by radio-frequency (RF) magnetron sputtering. X-ray diffraction analysis showed that there is no epitaxial relationship between ZION films fabricated at room-temperature (RT) and the sapphire substrates, while the films fabricated at 450oC grow epitaxially on the sapphire substrates. From the analysis of time evolution of the surface morphology, the process for the epitaxial growth of ZION on sapphire is found to consist of three stages. They are (i) initial nucleation of ZION crystallites with crystal axis aligned to the sapphire substrate, (ii) island growth from the initially formed nuclei and subsequent nucleation (secondary nucleation) of ZION crystallites, and (iii) lateral growth of ZION islands originated from initially formed nuclei. On the other hand, non-epitaxial ZION films fabricated at RT just grow in 3D mode. From these results, we conclude that the substrate temperature is the key to control of nucleation and subsequent epitaxial growth of ZION films on the lattice-mismatched substrate.

DOI： 10.1557/adv.2019.17

Language：Others  

Photoluminescence of (ZnO)0.82(InN)0.18 films -Incident light angle dependence-
We have fabricated a new semiconducting material, (ZnO)x(InN)1-x (called ZION hereafter), which is a pseudo-binary alloy of wurtzite ZnO (band gap: 3.4 eV) and wurtzite InN (band gap: 0.7 eV). We have succeeded in fabricating epitaxial (ZnO)0.82(InN)0.18 films on ZnO templates by RF magnetron sputtering. XRD measurements show that the full width at half maximum of the rocking curves from (101) plane and (002) plane are significantly small of 0.11 ? and 0.16 ?, respectively, indicating good in-plane and out-of-plane crystal alignment. High crystal quality of the films was also proved by deducing the defect density from XRD analysis showing that the edge type dislocation density is low of 8.2×108 cm-2. Furthermore, we observed room temperature photoluminescence from ZION films as a parameter of incident angle of He-Cd laser light. The results indicate that an emission peak of 2.79 eV is originated from ZION.

DOI： 10.4028/www.scientific.net/MSF.941.2099

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

© 2018 The Author(s). The rapid growth in world population brings with it the need for improvement in the current technology for water purification, in order to provide adequate potable water to everyone. Although an advanced oxidation process has been used to purify wastewater, its action mechanism is still not clear. Therefore, in the present study we treat dye-polluted water with gamma rays and dielectric barrier discharge (DBD) plasma. We study the wastewater treatment efficiency of gamma rays and DBD plasma at different absorbed doses, and at different time intervals, respectively. Methyl orange and methylene blue dyes are taken as model dyes. To understand the effects of environment and humidity on the decolorization of these dyes, we use various gas mixtures in the DBD plasma reactor. In the plasma reactor, we use the ambient air and ambient air + other gas (oxygen, nitrogen, and argon) mixtures, respectively, for the treatment of dyes. Additionally, we study the humidity effect on the decolorization of dyes with air plasma. Moreover, we also perform plasma simulation in different environment conditions, to understand which major radicals are generated during the plasma treatments, and determine their probable densities.

DOI： 10.1038/s41598-018-21001-z

Language：Others  

Cross correlation analysis of fluctuation of interactions between nanoparticles and low pressure reactive plasmas
We analyzed fluctuations of interactions between low pressure reactive plasmas and nanoparticles formed in the plasmas, to shed light on origins of fluctuations of interactions and to control fluctuations in plasma processes. Spatiotemporal fluctuations of nanoparticle density develop not only in a linear way but also in a nonlinear way. The results suggest nonlinear interactions potentially induce spatial and temporal process fluctuations.

DOI： 10.4028/www.scientific.net/MSF.941.2104

Language：Others  

Effects of sputtering pressure on (ZnO)<inf>x</inf>(InN)<inf>1-x</inf> crystal film growth at 450?C
We studied effects of sputtering pressure on growth of (ZnO)x(InN)1-x crystal films deposited at 450°C by rf magnetron sputtering. Epitaxial growth of (ZnO)x(InN)1-x films was realized on single-crystalline ZnO template. X-ray diffraction measurements show that full width at half maximum of the rocking curves from the (101) plane of the films reaches minimum value of 0.11? at 0.5 Pa. The sputtering gas pressure is a key tuning knob for controlling the crystal quality of ZION films.

DOI： 10.4028/www.scientific.net/MSF.941.2093

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

© 2018 Author(s). Time-dependent behavior of particles measured using the laser light scattering method in a remote silane plasma has been investigated using both optical emission spectroscopy and quartz crystal microbalance. Laser-scattered particles were observed from 0.3 s after the plasma ignition and scattering increased rapidly until 3.0 s. In the 0-0.3 s region where no particles were observed, SiH and Hβ emission intensity as well as Si/SiH and Hβ/SiH intensity ratios increased rapidly. Laser-scattered particles decreased in number, 3.0 s after plasma discharge, but the deposition rate measured using the quartz crystal microbalance increased linearly. The relationships between time-resolved images of particle movements and their contribution to film deposition as well as plasma characteristics such as SiH and Hβ are presented. The results show that the particles contributing to film growth at the early stage of plasma are much higher in number than those in the stabilized state.

DOI： 10.1116/1.5037539

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

The effect of the H<inf>2</inf>/(H<inf>2</inf> + Ar) flow-rate ratio on hydrogenated amorphous carbon films grown using Ar/H<inf>2</inf>/C<inf>7</inf>H<inf>8</inf> plasma chemical vapor deposition
© 2018 Elsevier B.V. To produce hydrogenated amorphous carbon (a-C:H) films with high mass density at a high deposition rate and low substrate bias voltage, we deposited these films on a Si substrate by plasma chemical vapor deposition, using toluene as a source compound and varying the gas flow-rate ratio of H2/(H2 + Ar). By decreasing the gas flow-rate ratio from 55&#37; to 11&#37;, the hydrogen content in the films decreased, and the density of sp3 carbon atoms in the films increased, whereas their surface roughness increased. At the gas flow-rate ratio of 11&#37;, we produced a-C:H films with a high bulk density of 1830 kg/m3 at a high deposition rate of 81.1 nm/min.

DOI： 10.1016/j.tsf.2018.02.035

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

DOI： 10.1166/sam.2018.3303

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

© 2018 The Japan Society of Applied Physics. The transportation of reactive oxygen species (ROSs) in a tissue phantom after plasma irradiation was studied using a two-layered target consisting of a KI-starch gel reagent and an agarose tissue phantom. The two-layered target can visualize the two-dimensional concentration distribution of ROSs after passing through the tissue phantom. ROSs were accumulated in the tissue phantom by the plasma irradiation, and they continued to be transported in the depth direction with the standing time after the plasma irradiation. The amount of ROS after passing through the tissue phantom increased in proportion to both plasma irradiation time and standing time. In this case, the ROS distribution patterns did not depend on these times. The ROS transportation speed after plasma irradiation was 0.05 mm/min in the tissue phantom. The ROS penetration rate depended on the standing time, not on the plasma irradiation time, and it was less than 1&#37;.

DOI： 10.7567/JJAP.57.01AG01

Language：Others  

Synthesis of nanoparticles using low temperature plasmas and its application to solar cells
We have succeeded in continuously fabricating size-controlled crystalline silicon nanoparticles by using low temperature plasma. For controlling size and structure, gas pressure and H2 dilution ratio of SiH4 are key parameters. We fabricated Schottky cells using synthesized Si nanoparticles which shows multiple exciton generation for photon energy with 3 times larger than their band gap. We utilized the particles to nanoparticle-sensitized solar cells which show the world best efficiency. Moreover, we found the nanoparticle composite polymer counter electrode is promising to low-cost and high performance solar cells.

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

We report low temperature (100-170 degrees C) and rapid (10 min) formation of crystalline Ge films between Au catalyst film and quartz glass substrate using a radio frequencymagnetron sputtering deposition. The formation rate of crystalline Ge films between Au catalyst film and quartz glass substrate is proportional to the deposition rate of Ge film, namely the flux of Ge atoms. To obtain insights on the formation mechanism of crystalline Ge films, we studied dependence of grain size of Au films on annealing temperature and Au film thickness. CrystallineGe films formed belowAu films have randomcrystalline orientationwith in-plane grain size frombelow1 mu m. Small crystalline grain size of Au films is needed to form rapidly Au induced crystalline Ge films. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2017.02.067

Language：Others  

Catalytic enhancement of polymer counter electrode in dye-sensitized solar cells
A counter electrode of dye-sensitized solar cells plays a significant role in the reduction of tri-iodide with electrolyte as a catalyst. Thus, the counter electrode of dye-sensitized solar cells is an important component, which often limits the cell performance. Some materials such as carbon, graphene, carbon nano-tube, transition metal and compounds, and polymer have been investigated as counter electrode materials. However, Pt is still the dominant counter electrode material despite its high cost. This work focused on a low-cost polymer as a counter electrode material of dye-sensitized solar cells. Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) was applied for the counter electrode. As similar to previous studies on PEDOT:PSS counter electrode, initial photovoltaic performance of dye-sensitized solar cells based on PEDOT:PSS counter electrode was lower than that of Pt counter electrode. Especially, fill factor of dye-sensitized solar cells was significantly decreased from Pt to PEDOT:PSS counter electrodes. To improve the catalytic properties of polymer counter electrodes, this work introduced nanoparticles into polymer layer. Nanoparticle addition increased the surface area of polymer counter electrode and activated the catalytic reactions. Consequently, we have realized the dye-sensitized solar cells with the polymer nanocomposite counter electrode containing PEDOT:PSS and nanoparticles exhibiting higher efficiency and photocurrent than the dye-sensitized solar cells based on Pt counter electrode.

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

© 2017 Elsevier B.V. Suppressing cluster incorporation into hydrogenated amorphous silicon films deposited by SiH4discharge plasma is the key to better film stability, because cluster incorporation contributes significantly to the formation of SiH2bonds which are closely related to light-induced degradation of the films. Here, we report hysteresis in the deposition rate and the volume fraction of clusters incorporated into a-Si:H films deposited by SiH4plasma CVD; the deposition rate and the volume fraction show looping behaviors when sequentially changing the discharge power, because clusters formed in the previous condition tend to remain in plasma and affect significantly the deposition rate and the volume fraction. The hysteresis is also shown as a function of SiH* emission intensity, being proportional to the radical generation rate due to electron impact dissociation of SiH4. By utilizing the hysteresis phenomenon, the volume fraction of clusters in films can be reduced significantly. We propose a model of plasma containing clusters, in which clusters play a key role in the hysteresis, namely the nonlinear behavior of the deposition rate and the volume fraction of clusters in films. Eventually, we deposited a-Si:H films of low cluster incorporation at a high deposition rate of 0.09 nm/s utilizing the hysteresis phenomena.

DOI： 10.1016/j.surfcoat.2017.01.034

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

As the finalization of a hydrogen experiment towards the deuterium phase, the exploration of the best performance of hydrogen plasma was intensively performed in the large helical device. High ion and electron temperatures, T-i and T-e, of more than 6 keV were simultaneously achieved by superimposing high-power electron cyclotron resonance heating onneutral beam injection (NBI) heated plasma. Although flattening of the ion temperature profile in the core region was observed during the discharges, one could avoid degradation by increasing the electron density. Another key parameter to present plasma performance is an averaged beta value <beta >. The high <beta > regime around 4&#37; was extended to an order of magnitude lower than the earlier collisional regime. Impurity behaviour in hydrogen discharges with NBI heating was also classified with a wide range of edge plasma parameters. The existence of a no impurity accumulation regime, where the high performance plasma is maintained with high power heating > 10 MW, was identified. Wide parameter scan experiments suggest that the toroidal rotation and the turbulence are the candidates for expelling impurities from the core region.

DOI： 10.1088/1741-4326/aa7fc2

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

Cold atmospheric plasma and gamma rays are known to have anticancer properties, even though their specific mechanisms and roles as co-solvents during their action are still not clearly understood. Despite the use of gamma rays in cancer therapy, they have oncogenic potential, whereas this has not been observed for plasma treatment (to date). To gain a better understanding, we studied the action of dielectric barrier discharge (DBD) plasma and gamma rays on the myoglobin protein. We analyzed the secondary structure and thermodynamic properties of myoglobin after both treatments. In addition, in the last few years, ammonium ionic liquids (ILs) have revealed their important role in protein folding as co-solvents. In this work, we treated the protein with ammonium ILs such as triethylammonium methanesulfonate (TEMS) and tetrabutylammonium methanesulfonate (TBMS) and later treated this IL-protein solution with DBD plasma and gamma rays. In this study, we show the chemical and thermal denaturation of the protein after plasma and gamma treatments in the presence and absence of ILs using circular dichroism (CD) and UV-vis spectroscopy. Furthermore, we also show the influence of plasma and gamma rays on the secondary structure of myoglobin in the absence and presence of ILs or ILs + urea using CD. Finally, molecular dynamic simulations were conducted to gain deeper insight into how the ILs behave to protect the protein against the hydrogen peroxide generated by the DBD plasma and gamma rays.

DOI： 10.1039/c7cp04083k

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

Polymer nano-composite composed of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) and TiO2 nano-particles was deposited on fluorine-doped tin oxide substrate and applied as an alternative to Au counter electrode of quantum dot-sensitized solar cell (QDSC). It became surface-richer with the increase in nano-particle amount so that catalytic reaction was increased by widened catalytic interface. Electrochemical impedance spectroscopy and cyclic voltammetry clearly demonstrated the enhancement of polymer nano-composite counter electrode. A QDSC based on polymer nano-composite counter electrode showed 0.56 V of V-OC, 12.24 mA cm(-2) of J(SC), 0.57 of FF, and 3.87&#37; of efficiency and this photovoltaic performance was higher than that of QDSC based on Au counter electrode (3.75&#37;). (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.electacta.2017.08.030

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

Both gamma rays and atmospheric pressure plasma are known to have anticancer properties. While their mechanism actions are still not clear, in some contexts they work in similar manner, while in other contexts they work differently. So to understand these relationships, we have studied Myoglobin protein after the treatment of gamma rays and dielectric barrier discharge (DBD) plasma, and analyzed the changes in thermodynamic properties and changes in the secondary structure of protein after both treatments. The thermodynamic properties were analyzed using chemical and thermal denaturation after both treatments. We have also studied the action of gamma rays and DBD plasma on myoglobin in the presence of osmolytes, such as sorbitol and trehalose. For deep understanding of the action of gamma rays and DBD plasma, we have analyzed the reactive species generated by them in buffer at all treatment conditions. Finally, we have used molecular dynamic simulation to understand the hydrogen peroxide action on myoglobin with or without osmolytes, to gain deeper insight into how the osmolytes can protect the protein structure from the reactive species generated by gamma rays and DBD plasma.

DOI： 10.1038/s41598-017-08643-1

Language：Japanese  

Synthesis of nanoparticles using low temperature plasmas and its application to solar cells

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

We report densities and surface reaction probabilities of O and N atoms during sputter deposition of ZnInON films on ZnO templates, measured via vacuum ultraviolet absorption spectroscopy. O density is almost constant of 4.5 x 10(11) cm(-3) irrespective of O-2 gas flow rate, whereas N density increases sharply from 2.7x10(11) cm(-3) for O-2 gas sccm to 7.7 x 10(11) cm(-3) for 0.6 sccm and it increases gradually 10(11) cm(-3) for 5 sccm. The surface reaction probability beta(O) of O atoms on ZnInON increases significantly from 0.022 to 0.404 with increasing O-2 gas flow rate from 0 to 5 sccm, whereas beta(N) of N atoms on ZnInON decreases slightly from 0.018 to 0.006. The stoichiometric chemical compositional ratio of ZnInON films with [Zn]/([Zn] + [In]) = [O]/([O] + [N]) = 94&#37; is obtained at beta(O) = 0.404 of O atoms. This stoichiometric compositional ZnInON films grow coherently on ZnO templates, while nonstoichiometric films do not. The stoichiometric chemical composition is the key to coherent growth of ZnInON films.

DOI： 10.1109/TPS.2016.2632124

Language：Others  

Influence of plasma irradiation on silkworm
© 2017 by Begell House, Inc. Silkworms have recently been proposed as an animal model for safety testing in basic research. We propose using silkworms for in vivo trials of direct plasma treatment. In this study, the influence of plasma irradiation on silkworms was investigated using a non-thermal atmospheric pressure plasma. Silkworm survival rate decreased with increasing low-frequency voltage and plasma irradiation period. Further investigation of the plasma-generated agents (oxygen related radicals, UV light, and charged particles), revealed that the contribution of charged particles significantly increases silkworm mortality.

Language：Japanese  

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

We present the effects of the application of a nonthermal plasma jet to a liquid surface on H2O2 and NO2- generation in the liquid. Two distinct plasma irradiation conditions, with plasma contact and with no observable plasma contact with the liquid surface, were precisely compared. When the plasma was made to touch the liquid surface, the H2O2 concentration of the plasma-treated water was much higher than the NO2- concentration. In contrast, when no observable contact of the plasma with the liquid surface occurred, the ratio of the NO2- to H2O2 concentration became over 1 and NO2- became more dominant than H2O2 in the plasma-treated water. Our experiments clearly show that reactive oxygen and nitrogen species can be selectively produced in liquid using appropriate plasma-irradiation conditions of the liquid surface. The ratio of NO2- to H2O2 was controlled within a wide range of 0.02-1.2 simply by changing the plasma-irradiation distance from the liquid surface. Published by AIP Publishing.

DOI： 10.1063/1.4968568

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

Semiconductor nanoparticles have significant potential for optoelectronic applications such as solar cells and light-emitting diodes. We are developing semiconductor nanoparticle composite films with a wide bandgap to be used as the window layer of solar cells because the bandgap energy increases with a decrease in the size of particles in the nanometer size range due to the quantum size effect. A multi-hollow discharge plasma chemical vapor deposition (CVD) method was used to fabricate Si nanoparticle composite films and control the volume fraction of nanoparticles in the films. The bandgap energy was increased from 2 eV for a crystalline volume fraction X-c of 0.2 to 2.5 eV for X-c = 0.6 and then decreased to 1.1 eV for X-c = 1. The photo and dark conductivity of films indicate high stability against light soaking. Si nanoparticle composite films with bandgap energies above 2.2 eV are thus promising candidate materials for the window layer of thin-film solar cells.

DOI： 10.1166/jnn.2016.13233

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

In this work, we have studied the action of dielectric barrier discharge (DBD) plasma irradiation using various feeding gases on seeds of Raphanus sativus L. and analysis their growth. Our experimental data shows that Air, O-2, and NO(10&#37;)+N-2 feeding gases plasma irradiation enhanced plant growth, whereas N-2, He and Ar feeding gases plasma irradiation had little influence on plant growth. Moreover, humid air plasma irradiation was more effective in growth enhancement than dry one. More than 2.3 times faster growth was observed by 3 min air plasma irradiation with 40-90&#37; relative humidity. The reactive species generated by plasma in gas phase were detected using optical emission spectroscopy and in liquid phase by electron spin resonance (ESR) spectroscopy. We concluded that OH and O radicals were key species for plant growth enhancement. (C) 2016 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.abb.2016.03.024

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

Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) was already used as a counter electrode material of dye-sensitized solar cells (DSCs) in other previous researches but its low catalytic activity has been a sticking point. Here we report the catalytic activation of PEDOT:PSS counter electrode by the surface modification using nano-particles. Nano-particle addition contributes to widening catalytic interface and improving catalytic characteristics of PEDOT:PSS counter electrode. However, only a few materials are applicable although various nano-particle materials were applied for the counter electrode of DSC. Catalytic characteristics of PEDOT:PSS counter electrodes with nano-particles are analyzed by cyclic voltammetry and electrochemical impedance spectroscopy. Finally, a DSC based on catalytically enhanced polymer counter electrode achieves 0.71 V of V-OC, 12.60 mA cm(-2) of J(SC), 0.75 of FF, and 6.65&#37; of efficiency, and it is higher than 5.60&#37; of efficiency of a DSC based on conventional Pt counter electrode. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.electacta.2016.06.020

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

In a dye-sensitized solar cell (DSC), a nano-porous semiconductor layer plays an important role in the performance. It determines open-circuit voltage and it affects the dye adsorption capacity and charge transfer, which are closely associated with photocurrent and overall performance. TiO2 is the most proper material for nano-porous layer since the first development of DSCs. This work focuses on the enhancement of TiO2 by doping. Sulfur (S) doping enhances charge transfer and the photo-conversion of TiO2. Therefore, the increase in photocurrent and efficiency is expected by S doping. S is doped into TiO2 by hydrolysis method. The amount of S is varied and their photo-responses are verified. The most effective S doped TiO2 is applied to DSCs. Overall performance of DSC is enhanced by the addition of S doped TiO2. Especially, the photocurrent is much increased by the improvement on charge transfer, electron lifetime, and photo-conversion. The photovoltaic properties of DSCs are investigated with various ratios of undoped and S doped TiO2. Finally, a DSC based on undoped and S doped TiO2 ratio of 1:1 has the highest efficiency, better than that of a standard DSC based on undoped TiO2.

DOI： 10.1007/s13391-016-4018-8

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

The two-dimensional concentration distribution of reactive oxygen species (ROSs) transported through an agarose-film tissue phantom by atmospheric-pressure plasma-jet irradiation is visualized using a KI-starch gel reagent. Oxygen addition to helium enhances ROS transportation through the film. A radial ROS distribution pattern at the plasma-irradiated film surface changes into a doughnut-shaped pattern after passing through the film. The ROS transportation speed is 0.14-0.2mm/min. We suggest that there are two types of ROS transportation pathways in the plasma-irradiated film: linear and circular. The majority of ROSs are transported through the circular pathway. ROS concentration distributions changed markedly with irradiation distance. Diffusive ROS transportation due to a concentration gradient is negligible in plasma-irradiated films. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/APEX.9.076202

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

We have measured the hydrogen content ratio ISiH2/ISiH associated with Si-H-2 and Si-H bonds in p-i-n (PIN) a-Si:H solar cells by Raman spectroscopy. With decreasing ISiH2/ISiH, the efficiency, short-circuit current density, open-circuit voltage, and fill factor of PIN a-Si: H solar cells after light soaking tend to increase. Namely, ISiH2/ISiH correlates well with light-induced degradation of the cells. While a single I-layer has a low ISiH2/ISiH of 0.03-0.09, a PIN cell has ISiH2/ISiH = 0.18 because many Si-H-2 bonds exist in the P-layer and at the P/I interface of the PIN solar cells. To realize PIN solar cells with higher stability, we must suppress Si-H-2 bond formation in the P-layer and at the P/I interface. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.07LE03

Language：English  

Correlation between SiH
We have measured the hydrogen content ratio I<inf>SiH2</inf>/I<inf>SiH</inf>associated with Si–H<inf>2</inf>and Si–H bonds in p–i–n (PIN) a-Si:H solar cells by Raman spectroscopy. With decreasing I<inf>SiH2</inf>/I<inf>SiH</inf>, the efficiency, short-circuit current density, open-circuit voltage, and fill factor of PIN a-Si:H solar cells after light soaking tend to increase. Namely, I<inf>SiH2</inf>/I<inf>SiH</inf>correlates well with light-induced degradation of the cells. While a single I-layer has a low I<inf>SiH2</inf>/I<inf>SiH</inf>of 0.03–0.09, a PIN cell has I<inf>SiH2</inf>/I<inf>SiH</inf>= 0.18 because many Si–H<inf>2</inf>bonds exist in the P-layer and at the P/I interface of the PIN solar cells. To realize PIN solar cells with higher stability, we must suppress Si–H<inf>2</inf>bond formation in the P-layer and at the P/I interface.

DOI： 10.7567/JJAP.55.07LE03

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

The multiple exciton generation characteristics of quantum dots have been expected to enhance the performance of photochemical solar cells. In previous work, we first introduced Si quantum dot for sensitized solar cells. The Si quantum dots were fabricated by multi-hollow discharge plasma chemical vapor deposition, and were characterized optically and morphologically. The Si quantum dot-sensitized solar cells had poor performance due to significant electron loss by charge recombination. Although the large Si particle size resulted in the exposure of a large TiO2 surface area, there was a limit to ho much the particle size could be decreased due to the reduced absorbance of small particles. Therefore, this work focused on decreasing the internal impedance to improve charge transfer. TiO2 was electronically modified by doping with vanadium, which can improve electron transfer in the TiO2 network, and which is stable in the redox electrolyte. Photogenerated electrons can more easily arrive at the conductive electrode due to the decreased internal impedance. The dark photovoltaic properties confirmed the reduction of charge recombination, and the photon-to-current conversion efficiency reflected the improved electron transfer. Impedance analysis confirmed a decrease in internal impedance and an increased electron lifetime. Consequently, these improvements by vanadium doping enhanced the overall performance of Si quantum dot-sensitized solar cells.

DOI： 10.1166/jnn.2016.12210

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

The impact of irradiation distances on plasma jet-induced specific effects on the supply of reactive oxygen species (ROS) to the bottom of a Petri dish filled with liquid was investigated using a KI-starch gel reagent that can be employed as a ROS indicator even in water. O-3 exposure experiments without plasma irradiation were also performed to elucidate the specific effects of the plasma jet. Relative concentrations of ROS transported to the bottom were evaluated using absorbance measurements. The results indicated that ROS supply to the bottom is markedly enhanced by the plasma jet irradiation at shorter irradiation distances, whereas similar results could not be obtained for the O-3 exposure. In these cases, the liquid mixing in the depth direction was also enhanced by the plasma jet irradiation only, and the supply of reactive atomic oxygen to the liquid surface was markedly increased as well. Published by AIP Publishing.

DOI： 10.1063/1.4948430

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

A counter electrode of dye-sensitized solar cells (DSC) is an important component, which often limits the cell performance. Here we report a low-cost and high-performance polymer counter electrode of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) containing TiO2 nano-particles for dye-sensitized solar cells. Catalytic characteristics of the counter electrode are significantly improved by adding TiO2 nano-particles to PEDOT:PSS. This improvement is attributed to catalytic activation due to an increase in the surface area of the counter electrode and an increase in conductivity of PEDOT:PSS due to its structural change. A dye-sensitized solar cell using the polymer counter electrode shows 8.27&#37; of efficiency and 16.39 mA cm(-2) of short circuit current density, higher than 7.59&#37; of efficiency and 14.75 mA cm(-2) of short circuit current density of a cell with the conventional Pt counter electrode. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jpowsour.2015.12.112

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

Si is currently the most widely used material in the photovoltaics. Since the first development of Si photovoltaics, various types of Si solar cells, such as single-crystal and multicrystalline, amorphous and thin film, have been developed and commercialized. The present work focused on Si quantum dots as another route to Si photovoltaics. To apply Si quantum dots to photovoltaic devices, the quantum characteristics of Si nano particles should be verified, and so 4 nm crystalline Si nano-particles were fabricated by multi-hollow discharge plasma chemical vapor deposition. The size and distribution of these particles were determined by transmission electron microscopy and compared against theoretically calculated values. These particles were applied to the fabrication of a Schottky cell and the quantum efficiency of the Si quantum dot layer was measured as a function of the incident photon energy. The quantum efficiency was found to exceed 100&#37; and so multiple exciton generation from the Si quantum dots was clearly realized.

DOI： 10.1166/sam.2016.2520

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

We have studied the effects of air nonthermal plasma irradiation of seeds of Arabidopsis thaliana (L.) on their growth from the beginning of cultivation to their harvest. Three minute plasma irradiation of dry seeds resulted in growth acceleration in all the growth stages. Compared with the control, the plasma irradiation led to an 11&#37; shorter harvest period, a 56&#37; increase in total seed weight, a 12&#37; increase in each seed weight, and a 39&#37; increase in seed number. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/APEX.9.016201

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

In our previous study, we realized conformal, subconformal, and anisotropic deposition profiles of hydrogenated amorphous carbon (a-C:H) films formed on trench substrates by plasma CVD using toluene. To obtain information on the film structures, we investigated the effects of deposition rate and ion bombardment on hydrogen bonding configurations and hydrogen content in the a-C: H films deposited by plasma CVD using toluene. The structure of a-C: H films transforms from polymer-like a-C:H (PLCH) for the ion energy <75 eV to diamond-like a-C: H (DLCH) for the ion energy; 75 eV. The hydrogen bonding configurations in a-C: H films are closely related to the ion energy, whereas they are less dependent on ion flux and deposition rate. The mass density increases gradually with decreasing hydrogen content in the PLCH region, and it increases sharply with decreasing hydrogen content in the DLCH region. This difference is due to the different C-C sp(3) concentration in PLCH and DLCH films. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.01AA11

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

The suppression of cluster incorporation into a-Si: H films is the key to better film stability, because incorporated clusters contribute to the formation of SiH2 bonds and hence lead to light-induced degradation of the films. To deposit stable a-Si: H solar cells at a high deposition rate (DR), we studied the effects of the gas flow rate on DR and the number of Si clusters incorporated into a-Si: H films with discharge power as a parameter, using a multihollow discharge-plasma chemical vapor deposition method. We succeeded in depositing high-quality a-Si: H films with the incorporation of few clusters at DR of 0.1nm/s. We also found that, under a low gas flow rate and a high discharge power, high-density clusters exist in plasma and hence DR is reduced as a result of radical loss to the clusters. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.01AA19

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

The presence of salts in biological solution can affect the activity of the reactive species (RS) generated by plasma, and so they can also have an influence on the plasma-induced sterilization. In this work, we assess the influence that diethylammonium dihydrogen phosphate (DEAP), an ionic liquid (IL), and sodium chloride (NaCl), an ionic salt (IS), have on the structural changes in hemoglobin (Hb) in the presence of RS generated using dielectric barrier discharge (DBD) plasma in the presence of various gases [O-2, N-2, Ar, He, NO (10&#37;) + N-2 and Air]. We carry out fluorescence spectroscopy to verify the generation of (OH)-O-center dot with or without the presence of DEAP IL and IS, and we use electron spin resonance (ESR) to check the generation of H-center dot and (OH)-O-center dot. In addition, we verified the structural changes in the Hb structure after treatment with DBD in presence and absence of IL and IS. We then assessed the structural stability of the Hb in the presence of IL and IS by using molecular dynamic (MD) simulations. Our results indicate that the IL has a strong effect on the conservation of the Hb structure relative to that of IS against RS generated by plasma.

DOI： 10.1038/srep17781

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

We present here an analysis of the discharge characteristics near the liquid surface in the plasma jet operated at a He gas flow rate of 1.5-10 slm. The plasma diameter on the liquid surface increases with an increase in He gas flow rate, which results in an increase in the total amount of charge particles transferred from the plasma to the liquid. We also analyzed the gas flow patterns using a Schlieren gas flow imaging system. The diameter of the laminar flow and the gas flow distance along the liquid surface increase with an increase in He gas flow rate, which well explains the increase in the plasma diameter on the liquid surface. Our experiments clearly demonstrate that high gas flow rate realizes the large reaction area between the water molecule and the plasma in the plasma jet system.

DOI： 10.1109/TPS.2015.2488619

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

Nanoparticles have great potential for medical applications such as cancer therapy, whereas their toxic effects on human body are pointed out. To study kinetics and toxicity of nanoparticles in living body, we synthesized indium-containing nanoparticles in aqueous suspension using pulsed electrical discharge plasmas in water, because no indium compounds exist in the living body in the normal situation and hence indium-containing nanoparticles are useful tracer materials for analyzing kinetics of nanoparticles in living body. The mean size of synthesized primary nanoparticles is 7 nm, whereas the mean size of secondary nanoparticles is 315 nm. EDX and XRD analysis reveal that nanoparticles are indium crystalline and indium hydroxide crystalline with the mass ratio of 8:2. Preliminary subcutaneous administration of nanoparticles to mice shows that indium is transported from subcutaneous to blood. These results show that synthesized indium-containing nanoparticles are useful for analyzing kinetics of nanoparticles in living body.

DOI： 10.1166/jnn.2015.11427

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

Tandem dye-sensitized solar cells (DSCs) are very effective to improve light absorption characteristics and overall performance. The structure of conventional tandem DSC is an assembly of two independent DSCs. Therefore, additional TiO2 layer, Pt film, and transparent conductive oxide (TCO) electrodes weaken incident light to the bottom cell and complicate the fabrication as compared with standard DSCs. Here, this work proposed the structural alternation of tandem DSC as a solution. Mesh type of counter electrode was inserted between top and bottom cells instead of TCO electrodes. Two photo electrodes shared electrolyte and counter electrode in this structure. High aperture ratio of mesh increased light penetration into bottom cell and led to the performance improvement. Structural alternation also simplified the fabrication. It could be fabricated like standard DSCs. After dye arrangement and TiO2 layer of bottom cell were controlled, the photovoltaic performance of proposed tandem DSC was enhanced and it was higher than conventional tandem DSC. Finally, the long-term stability of proposed tandem DSC was secured by the control of sealing walls. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.electacta.2015.04.105

Language：Others  

Synthesis of indium-containing nanoparticles using plasmas in water to study their effects on living body
Nanoparticles can be employed for biomedical applications such as biomarkers, drug delivery systems, and cancer therapies. They are, however, pointed out their adverse effects on human body. Here, we synthesed indium-containing nanoparticles using discharge plasmas with indium electrodes immersed in DI water and administrated nanoparticles to rats to analyze their kinetics in living body. The discharge power was 5.1 W. The electron density is 5x1017/cm3 deduced from Stark broadening of hydrogen lines. TEM observation shows the mean size of primary nanoparticles is 7 nm. The nanoparticles are indium crystalline and indium hydroxide crystalline. The synthesized nanoparticles and purchased nanoparticles (In2O3, <100nm) were administrated to rats using subcutaneous injection. Indium of 166.7 g/day (synthesized) and of 27.8 g/day (purchased) are detected from the urine at 12 weeks after the administration. Synthesized nanoparticles dispersed in water are useful for analyzing kinetics of nanoparticles in living body. Work partly supported by KAKENHI.

Language：Others  

Attraction during binary collision of fine particles in Ar plasma
Forces exerted on fine particles in plasmas play central roles in their transport, agglomeration, as well as Coulomb crystals and liquids. The forces are complicated because of charge fluctuation of fine particles, charge screening in plasma, anisotropy of plasma flow, and so on. Various formulas of such forces have been theoretically predicted but many of them have not been supported by experimental results yet. Here we carried out experiments on binary collision of fine particles using Ar rf-discharge plasmas. PMMA fine particles of 10 μm diameter were injected into the plasma and they were levitated around the plasma sheath boundary. The number of fine particles levitated was so small that we can observe non-collective pair interaction. We observed binary collisions of fine particles with a high speed and high resolution camera. We found that repulsion of two fine particles takes place in short distances, whereas attraction takes place in middle distances. These results indicate that inter-molecular like potential exists between them. The attraction corresponds to non-collective fine-particle attraction due to shadow effects.

Language：Others  

Cluster Incorporation into A-Si:H Films Deposited Using H 2 +SiH 4 Discharge Plasmas
Light-induced degradation is the most important issue for hydrogenated amorphous silicon (a-Si:H) solar cells. Our previous results have suggested that incorporation of clusters into films is responsible for the light-induced degradation. Therefore, it is important to control the incorporation of clusters. Recently, we have developed multi-hollow discharge plasma CVD method, by which clusters are driven toward the downstream region and high quality a-Si:H films can be deposited in the upstream region. Here, we report effects of H2 dilution on cluster incorporation. Cluster size was measured by TEM, and the incorporation amount of clusters was measured with quartz crystal microbalances. H2 dilution leads to smaller clusters and the cluster incorporation in the upstream region increases with H2 dilution because the diffusion velocity of such small clusters much surpasses gas flow velocity.

Language：Others  

Cross correlation analysis of plasma perturbation in amplitude modulated reactive dusty plasmas
Interactions between plasmas and nano-interface are one of the most important issues in plasma processing. We have studied effects of plasma perturbation on growth of nanoparticles in amplitude modulated reactive dusty plasmas and have clarified that amplitude modulation (AM) leads to suppression of growth of nanoparticles [1]. Here we report results of cross correlation analysis of time evolution of laser light scattering intensity from nanoparticles in reactive plasmas. Experiments were carried out using a capacitively-coupled rf discharge reactor with a two-dimensional laser light scattering (LLS) system. We employed Ar +DM-DMOS discharge plasmas to generate nanoparticles. The peaks at higher harmonics and subharmonics in spectra of laser light scattering intensity were detected, suggesting nonlinear coupling between plasma and nanoparticle amount. We found high cross correlation t between waves at AM frequency and its higher harmonics. Namely, perturbation at fAM closely correlates with those at higher harmonics.

Language：Others  

Deposition rate and etching rate due to neutral radicals and dust particles measured using QCMs together with a dust eliminating filter
We have developed an in-situ method for measuring deposition rate of radicals and dust particles using quartz crystal microbalances (QCMs) together with a dust eliminating filter. The QCMs have three channels of quartz crystals. Channel 1 was used to measure total deposition rate due to radicals and dust particles. Channel 2 was covered with a dust eliminating filter. Channel 3 was covered with a stainless-steel plate. Moreover, all QCMs are covered with a grounded stainless steel mesh for suppressing influx of charged particles. The measurements were conducted in the Large Helical Device in the National Institute for Fusion Science, Japan. Although the deposition measurements during the discharges were difficult, we obtained deposition rate and etching rate by comparing the data before and after each discharge. The frequency difference for channel 1 changes from 0.1 Hz (etching) to -0.5 Hz (deposition), while those for channels 2 and 3 are within a range of +/-0.1 Hz and +/-0.05 Hz, respectively. The QCM method gives information on deposition rate and etching rate due to neutral radicals and dust particles.

Language：Others  

Effects of electrode structure on characteristics of multi-hollow discharges
Silane plasmas are widely employed for hydrogenated amorphous silicon (a-Si:H) film deposition. Amorphous silicon nanoparticles below 10 nm in size (clusters) are formed in silane plasmas and some of them are incorporated into a-Si:H films, leading to the light induced degradation which is the most important issue for a-Si:H solar cells. To suppress cluster incorporation, a multi-hollow discharge plasma CVD method has been developed and succeeded in depositing highly stable a-Si:H films. For further improvement of the film qualities, we have employed a thicker grounded electrode to suppress plasma expansion toward the deposition region. From optical images of the discharge plasmas, the expansion was significantly suppressed using 10 mm thick grounded electrode. For the 10 mm thick electrode, optical emission intensity ratio of Si* (288 nm) and SiH* (414 nm) ISi*/ISiH*, which shows a ratio of cluster generation ratio and radical ones, was 20&#37; of that for 1mm thick electrode. These results suggest that the generation of clusters was also suppressed using the 10 mm thick grounded electrode.

Language：Others  

Effects of N2 dilution on fabrication of Ge nanoparticles by rf sputtering
Multiple exciton generation (MEG) in QDs is expected to enhance significantly the energy conversion efficiency of solar cells. Although there are several reports on MEG characteristics from various QD materials such as PbS, CdSe, CdS ZnS, and Ag2S, such materials have disadvantages of their toxicity and limited resources. Here we have developed quantum-dots (QDs) solar cells using Ge nanoparticles fabricated by rf sputtering method under high pressure. We fabricated Ge nanoparticles by rf sputtering at a pressure of 1.5 Torr. Since the mean free path of Ge atoms is an order of micrometer, and Ge nanoparticles are formed in gas phase. We fabricated Ge nanoparticles using Ar and N2 to terminate surface defects by N. Ge and Ar emission intensities decrease significantly with increasing N2 partial pressure. The electron density was measured with a plasma absorption probe. The electron density decreases with increasing N2 partial pressure.

Language：Others  

Laser trapped single fine particle as a probe of plasma parameters”
Here we report evaluation of electron density and temperature using optically trapped single fine particle. Experiments were carried out with a radio frequency low pressure plasma reactor, where we set two quartz windows as top and bottom flanges to irradiate an infrared laser light of 1064 nm wavelength from the bottom side. Ar plasmas were generated between a powered ring-electrode set at the bottom of the reactor and a grounded mesh placed at the center of the reactor at 100 Pa by applying 13.56 MHz voltage. The particles injected into the plasmas were monodisperse methyl methacrylate-polymer spheres of 10 μm in diameter. A negatively charged particle, which is suspended plasma sheath boundary, was trapped at the focal point of the irradiated laser light due to the transfer of momentum from the scattering of incident photons. At the beginning of the trapping, particle of 10 μm in size was trapped above 505 μm from the bottom window. After 230 min, the size and position were 9.56 μm and 520 μm, respectively. From the results, the electron density and temperature are deduced to be 1.7×109 cm-3 and 1.9 eV.

Language：Others  

Raman spectroscopy of PIN hydrogenated amorphous silicon solar cells
Light-induced degradation of hydrogenated amorphous silicon (a-Si:H) is a key issue for enhancing competitiveness in solar cell market. A-Si:H films with a lower density of Si-H2 bonds shows higher stability. Here we identified Si-H2 bonds in PIN a-Si:H solar cells fabricated by plasma CVD using Raman spectroscopy. A-Si:H solar cell has a structure of B-doped μc-SiC:H (12.5 nm)/ non-doped a-Si:H (250nm)/ P-doped μc-Si:H (40 nm) on glass substrates (Asahi-VU). By irradiating HeNe laser light from N-layer, peaks correspond to Si-H2 bonds (2100 cm-1) and Si-H bonds (2000 cm-1) have been identified in Raman scattering spectra. The intensity ratio of Si-H2 and Si-H ISiH2/ISiH is found to correlate well to light induced degradation of the cells Therefore, Raman spectroscopy is a promising method for studying origin of light-induced degradation of PIN solar cells.

Language：Others  

Simple Evaluation Method of Atmospheric Plasma Irradiation Dose using pH of Water
Atmospheric discharge plasmas are promising for agricultural productivity improvements and novel medical therapies, because plasma provides high flux of short-lifetime reactive species at low temperature, leading to low damage to living body. For the plasma-bio applications, various kinds of plasma systems are employed, thus common evaluation methods are needed to compare plasma irradiation dose quantitatively among the systems. Here we offer simple evaluation method of plasma irradiation dose using pH of water. Experiments were carried out with a scalable DBD device. 300 μl of deionized water was prepared into the quartz 96 microwell plate at 3 mm below electrode. The pH value has been measured just after 10 minutes irradiation. The pH value was evaluated as a function of plasma irradiation dose. Atmospheric air plasma irradiation decreases pH of water with increasing the dose. We also measured concentrations of chemical species such as nitrites, nitrates and H2O2. The results indicate our method is promising to evaluate plasma irradiation dose quantitatively.

Language：Others  

Substrate temperature dependence of Au-induced crystalline Ge film formation using sputtering deposition
We are developing Au-induced crystalline Ge film formation using sputtering deposition. For the method, very thin Au films were deposited on SiO2 substrates and then Ge atoms were irradiated to the Au films by sputtering. We found two kinds of Ge film growth: one is Ge film formation on Au films, and the other is Ge film formed between Au films and SiO2. The latter film formation, however, takes place in a narrow temperature range around 140°C. Here we report two kinds of substrate temperature dependence of Ge film formation: one is annealing temperature of Au films, and the other is the substrate temperature dependence during Ge sputtering. 30nm-thick Au films were deposited quartz glass as a catalyst at room temperature by sputtering. Then the Au films were annealed in a temperature range from room temperature to 190 °C in a vacuum. Au grain grows and crystal orientation shows better alignment as the annealing temperature rises. We found that the smaller grain size with random orientation is better for Ge film formed between Au films and SiO2.

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

We are developing a dust monitoring method using quartz crystal microbalances (QCMs) equipped with a dust eliminating filter. Here we report a dust eliminating ratio of the filter and first measurement results of the QCMs in a divertor simulator. The volume of spherical dust in unit area on the filter and QCM under the filter were 2.09 x 10(-9) and 1.22 x 10(-19) m(3) m(-2), respectively. Thus, the dust eliminating ratio of the filter is 94.2&#37;. The QCM without the filter gives deposition rate due to radicals and dust particles, whereas the QCM with the filter gives deposition rate predominantly due to radicals. From the results, we deduce information of mass fraction of dust particles in deposits. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2014.10.049

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

We report on fabrication and photovoltaic characteristics of solar cells with ZnInON/ZnO multi-quantum wells (MQWs) in the intrinsic layer of p-i-n structure by RFmagnetron sputtering. We employed two kinds of p layers: one is p-GaN and the other is p-Si. Under solar simulator light, the short-circuit current (J(sc)) and the open-circuit voltage (V-oc) of the solar cells on p-GaN templates are 1.9 mu A/cm(2) and 0.16 V, whereas J(sc) and V-oc are enhanced to 2.5 mu A/cm(2) and 0.19 V under simultaneous irradiation of green laser light (532 nm) and the solar simulator light. Solar cells on p-Si substrates do not show such enhancement. A possible origin of the enhancement is a large piezoelectric field generated in strained ZnInON wells coherently grown on p-GaN template. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2015.01.012

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

We present here analysis of oxidation reaction in liquid by a plasma-jet irradiation under various gas flow patterns such as laminar and turbulence flows. To estimate the total amount of oxidation reaction induced by reactive oxygen species (ROS) in liquid, we employ a KI-starch solution system, where the absorbance of the KI-starch solution near 600 nm behaves linear to the total amount of oxidation reaction in liquid. The laminar flow with higher gas velocity induces an increase in the ROS distribution area on the liquid surface, which results in a large amount of oxidation reaction in liquid. However, a much faster gas flow conversely results in a reduction in the total amount of oxidation reaction in liquid under the following two conditions: first condition is that the turbulence flow is triggered in a gas flow channel at a high Reynolds number of gas flow, which leads to a marked change of the spatial distribution of the ROS concentration in gas phase. Second condition is that the dimpled liquid surface is formed by strong gas flow, which prevents the ROS from being transported in radial direction along the liquid surface. (C) 2015 AIP Publishing LLC.

DOI： 10.1063/1.4927217

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

We studied the effects of incorporation of hydrogenated amorphous silicon (a-Si:H) nanoparticles (clusters) generated in the initial discharge phase on light induced degradation of a-Si:H films. The amount of clusters incorporated into the films in the initial discharge phase is 15 times larger than that in the steady state. To evaluate the effects of such initial cluster incorporation on stability of a-Si:H films, we fabricated a-Si:H Schottky cells with and without initial cluster incorporation using a multi-hollow discharge plasma chemical vapor deposition method with a shutter and compared cell stability against light exposure. The degradation ratio of the cell without initial cluster incorporation is less than 1&#37; even after 100 hour light soaking of 2.7 suns. Our results show that suppressing initial cluster incorporation into a-Si:H films is a key to stable a-Si:H cells. Moreover, Si-H-2 bonds in films can be reduced down to 1/10 using a cluster eliminating filter. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2015.02.052

Language：English  

Effects of discharge voltage on the characteristics of a-C:H films prepared by H-assisted Plasma CVD method
Hydrogen bonding configurations and hydrogen content of a-C:H films deposited by H-assisted plasma CVD were investigated by Fourier transform infrared spectroscopy. Plasma parameters related to deposition rate were derived using optical emission spectroscopy. The a-C:H films contain a large number of sp³ configurations (93&#37;) and a few sp² configurations (7&#37;). Most of the hydrogen is bonded in methyl groups which shows the structure of deposited a-C:H films is polymer-like carbon. The mass density has nearly linear decreases with increasing the hydrogen atom density, indicating that control of hydrogen content is crucial to obtain a-C:H films of high mass density. A slight increase in radical generation rate and significant increases in etching rate by hydrogen atoms lead to decrease the deposition rate when the discharge voltage increases from 170 V to 180 V.

DOI： 10.14723/tmrsj.40.123

Language：English  

Deposition of Carbon Films on PMMA Using H-assisted Plasma CVD

DOI： 10.7566/JPSCP.1.015072

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

Dye-sensitized solar cells (DSCs) still need wider absorption range despite their stable and good performance. This work proposed the co-sensitization of Si quantum dot (QD) and N749 dye for better photo-generation. Si QD was chemically stable with regard to all DSC components and its stability enabled to co-sensitize with dye. Si QDs were fabricated by multihollow discharge plasma chemical vapor deposition and applied for the co-sensitization. Si and dye co-sensitization led to the increase of incident photon to current conversion efficiency and decrease of internal impedance as compared with a standard DSC. As a result, short-circuit current density was increased over 1 mA/cm(2) and the performance was enhanced with co-sensitization from 4.36 to 5.10&#37;. Si and dye co-sensitization was very effective because the enhancement was much larger than the performance of Si QDSC without dye sensitization. (C) 2015 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.54.01AD02

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

Cyclic transport of dust particles (dust hour glass) in a capacitively coupled radio frequency discharge with horizontal electrodes is demonstrated. Dust transport toward the upper electrode is initiated by varying the electrical asymmetry of the discharge. A shaped upper electrode guides dust particles to move toward the center of the discharge. Subsequently, the dust drops through the plasma bulk spontaneously, this way returning to the starting location.

DOI： 10.1109/TPS.2014.2343975

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

A chemical interaction between an atmospheric pressure plasma jet and liquid media is of great interest for biomedical applications. In this paper, the visualization method and typical results of the 2-D distribution of oxidizing substances generated by the plasma jet were reported using the gel visualization reagent. The plasma jet generator consists of a glass tube and two electrodes. As a result, the distribution of oxidizing substances was able to be visualized around the contact point between the plasma jet and the reagent in atmospheric air. The interesting distribution patterns depending on the supplied gas were visually obtained by the reagent. In addition, its relative concentration distribution was also obtained by an absorbance measurement.

DOI： 10.1109/TPS.2014.2325038

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

We have synthesized ZnInON (ZION) semiconductor, a ZnO-based compound with tunable band gap, by radio-frequency magnetron sputtering on quartz glass, a-SiO2/Si, and GaN/Al2O3 templates. From XRD analysis using wide-range reciprocal-space mapping, ZION is deduced to be a pseudo-binary system of wurtzite ZnO and wurtzite InN, the c-axis lattice parameter of which varies continuously from 0.53 to 0.58 nm with decreasing the chemical composition ratio [Zn]/([Zn] + [In]). From optical measurements, we found that ZION has tunability of the band gap over the entire visible spectrum, and the photo-to-dark conductivity ratio is high, of 2.2 x 10(3), demonstrating the high photosensitivity of ZION films. We have also succeeded in the epitaxial growth of ZION films with the composition ratio (InN)/(ZnO) of about 50 at.&#37; by using GaN templates, where the FWHM of the ZION (002) rocking curve is small, of 350 arcsec. These results allow us to conclude that ZION will open up the field of group II-III-V-VI semiconductors that offer new opportunities for design of optoelectronic devices.

DOI： 10.1088/2053-1591/1/3/036405

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

High-quality epitaxial ZnO films on c-plane sapphire substrates have been obtained by utilizing an off-axis sputtering configuration together with buffer layers prepared via nitrogen-mediated crystallization (NMC). The role of NMC buffer layers is to provide high density of nucleation site and, thus, to reduce the strain energy caused by the large lattice mismatch (18&#37;) between ZnO and sapphire. The NMC buffer layers allow two-dimensional growth of subsequently grown ZnO films, being particularly enhanced by employing an off-axis sputtering configuration in which the substrate is positioned out of the high-energy particles, such as negative oxygen ions originating from the targets. As a result, ZnO films with smooth surfaces (root-mean-square roughness: 0.76 nm) and a high electron mobility of 88 cm(2)/V . s are fabricated. Photoluminescence spectra of the ZnO films show strong near-band-edge emission, and the intensity of the orange-red defect emission significantly decreases with increasing horizontal distance between the target and the substrate. From these results, we conclude that off-axis sputtering together with NMC buffer layers is a promising method for obtaining high-quality epitaxial ZnO films. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

DOI： 10.1117/1.OE.53.8.087109

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

Combinatorial analysis has been carried out to investigate the long-term effects of plasma irradiation of radish seeds on the subsequent sprout growth (Raphanus sativus L.) using atmospheric dielectric barrier discharge plasmas in air. The average seedling length was maximized with 180 s of plasma irradiation when the seed was 5 mm from the electrode edge and 3 mm below the electrode. With these parameters the average seedling length was 250&#37; longer than that not irradiated after three days of cultivation. Observation of the seeds using an infrared (IR) camera and scanning electron microscopy revealed that the temperature rise and etching of the seeds during the plasma irradiation have little effect on growth enhancement. The interaction between radicals and seeds for a duration of 180 s leads to the growth enhancement of radish sprouts for 7 days. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cap.2013.11.056

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

Au counter electrode is generally used with polysulfide electrolyte for quantum dot-sensitized solar cells (QDSCs) due to degradation of QD by iodine electrolyte and strong interaction between Pt counter electrode and S2- ions in polysulfide electrolyte. In this work, the effects of the thickness and morphology of Au counter electrode on the performance of Si QDSC were investigated. Au film thickness was linearly controlled from 5 to 500 nm by deposition time. Cyclic voltammetry and impedance analysis clarified the catalytic activity of counter electrode, surface resistance of transparent conductive oxide (TCO), and the charge transportation at the counter electrode. The increase of Au film thickness reduced the surface resistance of TCO with increased conductivity. No significant difference in the redox reaction from electrolyte to Si QDs was observed for Au film thickness from 20 to 500 nm. Catalytic reaction of counter electrode was activated with the increase of Au film thickness up to 200 nm. The impedance of charge transportation at the counter electrode was also decreased with Au deposition. Their surface resistance, catalytic activity and internal resistance were reflected in overall performance. Consequently, Si QDSC with 200-nm-thick Au counter electrode had the best performance. (C) 2014 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.53.05FZ01

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

A dye-sensitized solar cell is one of the representative photochemical solar cells. It has been actively studied and its performance has been much enhanced so far. For better performance, various additional layers such as compact, barrier, and light scattering layers have been applied. Compact and barrier layers suppress the charge recombination with redox electrolyte and light scattering layer improves the light harvesting. Although it was confirmed that these layers were clearly effective for the performance enhancement, there is still a variety of opinions concerning their electrochemical impedance analyses. Therefore, this work tried to analyze their effect on the internal impedance using electrochemical impedance spectroscopy. The most widely used materials were employed for the fabrication of additional layers. TiCl4 and Zn(NO3)(2)-6H(2)O aqueous solutions, and a 400 nmsized TiO2 were used for compact, barrier, and light scattering layers, respectively. The photovoltaic characteristics confirmed their effect on the performance and their impedance spectrawere analyzed according to high, middle, and low frequency bands. As a result, these layers mainly affected the impedance in the middle frequency range because the change of TiO2/dye/electrolyte interface was significantly associated with this impedance. Finally, all three layers were applied to a single cell and the performance was considerably increased with reduced charge recombination and improved light harvesting. (C) 2013 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.tsf.2013.08.103

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

This work first introduced Si quantum dots (QDs) for QD-sensitized solar cells (QDSCs). However, the particle size of Si QDs, which had visible light absorption, was relatively large. The paint-type Si QDSC was proposed in this work because Si QDs could not penetrate into nano-porous TiO2 network. Si QDs were synthesized by multi-hollow plasma discharge CVD and mixed with TiO2 paste. For better performance, thickness of Si-TiO2 layer was varied by coating times and Si-TiO2 films were optically and electrically analyzed. As a result, 6 times screen printed Si-TiO2 film had the best performance with the smallest internal impedance and the highest photon to current efficiency.

DOI： 10.1007/s12541-014-0343-8

Language：Japanese  

Performance enhancement of dye and Si quantum dot hybrid nanostructured solar cell with TiO2 barrier
Dye and quantum dot (QD) are representative sensitizers of the photochemical solar cells. Dye has the highest efficiency in the whole sensitizers. QDs have relatively low performance but their multiple exciton generation enhanced theoretical efficiency from 33 to 44&#37; and expected to achieve high efficiency. This work tried to enhance the photovoltaic performance with the co-sensitization of N719 dye and Si QD. The performance of dye and QD co-sensitized solar cell was not much enhanced because of electron loss of charge recombination. Therefore, TiO2 barrier layer was introduced on TiO2 and Si QD. It blocked the charge recombination with redox electrolyte. It also helped better electron injection from excited dye to TiO2 with strengthened dye adsorption. Consequently, the performance of co-sensitized solar cell was enhanced with reduced charge recombination and increased dye adsorption.

DOI： 10.14723/tmrsj.39.321

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

We propose a simple theoretical model that describes the correlation between plasma fluctuation and fluctuation of nanoparticle growth in reactive plasmas. The model predicts that the high density of nanoparticles brings about small mean-size, narrow size dispersion, and sharp size slope on the large side of the size distribution. The model suggests some methods of tuning the size dispersion, and it also suggests that a self-limiting process is the key to markedly suppressing fluctuations in nanostructure fabrication. All predictions coincide with the experimental results reported previously. Moreover, the model suggests that plasma fluctuation induces both the linear and nonlinear responses of nanoparticle growth. (C) 2014 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.53.010201