Hyomen Kagaku
Online ISSN : 1881-4743
Print ISSN : 0388-5321
ISSN-L : 0388-5321
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Volume 25, Issue 9
Displaying 1-12 of 12 articles from this issue
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Preface
Transaction of the 23rd Conference on Surface Science [III]
Originals
  • UHV-SEM Observation of Surface Electromigration with Silver Tip
    Katsuyoshi SAKAMOTO, Akiko NATORI, Katsuyasu KAWANO, Shuji HASEGAWA
    Article type: Original
    2004 Volume 25 Issue 9 Pages 534-540
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.534
    JOURNAL FREE ACCESS
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    We have observed the surface electromigration with a silver tip by UHV-SEM and micro-probe RHEED. The silver tip etched and cleaned by heating and melting in UHV was mounted on a micro-slider touching heated Si(111) samples. The bright area under the silver tip is spread to the direction of cathode, the structure of which is determined to be √3×√3 structure from RHEED patterns. We have observed different shapes depending on heating temperature: At low temperatures, the shape of spread is like a bar, because the driving force of surface electromigration is superior to that of diffusion. At high temperatures, the shape is like a circle, because the driving force of diffusion is superior to that of surface electromigration. Using the silver tip, surface electromigration can be observed at high temperatures where lots of silver atoms are evaporated. We have checked the reproducibility of surface electromigration with the silver tip which is a supply source for thin film formation.
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  • Behavior of Si Surface Hydrogen in Oxygen Plasma
    Masanori SHINOHARA, Teruaki KATAGIRI, Keitaro IWATSUJI, Yoshinobu MATS ...
    Article type: Original
    2004 Volume 25 Issue 9 Pages 541-547
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.541
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    We investigate the behavior of surface hydrogen on hydrogen-terminated (100), (110) and (111) surfaces in oxygen plasma atmosphere by using infrared absorption spectroscopy (IRAS) in multiple internal reflection (MIR) geometry. We measured the infrared absorption spectra in Si-H stretching vibration region. IRAS data demonstrated that all of the hydride species on the Si(111) surface is abstracted by oxygen plasma, and, on the other hand, a large part of the hydride on the Si(100) and (110) surfaces are abstracted but some of them are left even after a long plasma-exposure. The surface hydrogen left after the plasma-exposure is considered to be due to the migration into subsurface region where oxygen species cannot reach. Therefore, we conclude that the abstraction of the surface hydrogen by oxygen plasma does not depend on the crystallographic orientations of Si surfaces, but the migration of surface hydrogen into the subsurface region depends on the crystallographic orientations.
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  • Surface Structure of Rutile TiO2(001)
    Toshitaka KUBO, Hisakazu NOZOYE
    Article type: Original
    2004 Volume 25 Issue 9 Pages 548-554
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.548
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    Surface structures of rutile TiO2(001) have been studied by using scanning tunneling microscopy (STM) and first-principles total energy calculations. Prior investigations have observed many kinds of surface structures. However, detailed atomic structure and the common sense of the reconstructions are still unknown. We evaluate the energetical stability of the surface structures. The calculated results suggest that the {111}-microfaceted surface is energetically stabler than the unreconstructed surface. The nature of the reconstruction is explained in terms of microfaceting of the {111} plane, which is consistent with atomically resolved STM images.
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  • Electronic Structure Analysis of a h-BN Thin Film on Ni(111) using NEXAFS Spectroscopy
    Iwao SHIMOYAMA, Yuji BABA, Tetsuhiro SEKIGUCHI, Krishna G. NATH
    Article type: Original
    2004 Volume 25 Issue 9 Pages 555-561
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.555
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    In order to study the interaction between h-BN epitaxial monolayer and Ni(111) substrate, near edge X-ray absorption fine structure (NEXAFS) spectroscopy is used. B K-edge NEXAFS spectra of h-BN/Ni(111) show a new π* peak that does not appear in the spectrum of bulk h-BN. The modification of π* band of h-BN is investigated by discrete variational Xα (DV-Xα) molecular orbital calculation with a model cluster. Taking into accounts core hole effect, the origin of the new π* peak is explained in terms of partial density of states calculated by DV-Xα method. Theoretical approach clarifies that π* orbital of h-BN is mainly hybridized with 4p orbital of Ni substrate. This leads to the conclusion that h-BN monolayer is chemisorbed on Ni(111) substrate.
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  • Local Oxidation Induced by Inhomogeneous Stress on Blistered Si Surface
    Shinichi IGARASHI, Akiko N. ITAKURA, Masahiro KITAJIMA, Shinsuke NAKAN ...
    Article type: Original
    2004 Volume 25 Issue 9 Pages 562-567
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.562
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    Surface stress can be utilized positively in modifying the surface reaction potential and increasing the surface reactivity. It will be a technique for two-dimensional patterning of surface chemical reactions by means of surface stress modulation. Blister is a local protrusion of solid surface induced by gas ion irradiation, and is considered to create local stress on surface layers. Si(100) substrate was irradiated with H+ (ion energy of 10 keV and fluence of 1×1022 ions/m2) at an angle of 30o to the surface normal. The blisters of several μm in diameter at the bottom were formed. After the ion irradiation, the substrate was oxidized. By means of scanning Auger microscopy, we observed that the rims of the blisters have higher oxygen intensities than the flat surfaces and the tops have lower than the flats. The stress distribution of the blister was calculated using finite element methods; the surface layers should be stretched laterally at the top of blisters and are compressed at the rim, relative to the flat surfaces. The O distribution clearly consists with the stress distribution of the surface. Our results demonstrate a patterned oxidation of Si surface applying its reactivity depending on the surface stress.
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  • Oxidation Resistance of vitamin E Additive Ultra High Molecular Weight Polyethylene for an Artificial Knee Joint
    Satoshi TERAMURA, Naohide TOMITA, Shunichiro KAWASHIMA, Kazuhisa FUJIT ...
    Article type: Original
    2004 Volume 25 Issue 9 Pages 568-572
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.568
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    Oxidative degradation caused by γ-ray irradiation is a major problem that limits the durability of ultra high molecular weight polyethylene (UHMWPE) used for artificial knee joint systems. In this paper, we have investigated the oxidative degradation of UHMWPE surfaces in the depths of μm and nm by using infrared absorption measurement and by X-ray photoelectron spectroscopy (XPS), respectively. Infrared absorption shown by C=O peak indicates that the oxidation was uniform in the depth up to ∼200 μm. We found that the oxidation in the range of nm was appropriately evaluated by XPS of the O-1s spectrum region. It was also confirmed that the addition of vitamin E was effective to prevent the oxidation induced by γ-ray irradiation.
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  • Controlling Surface Dynamics by Vibrational Excitation of a Single Molecule
    —Acetylene Molecules on Pd(111)—
    Chikako MATSUMOTO, Yousoo KIM, Yasuyuki SAINOO, Toshiro OKAWA, Maki KA ...
    Article type: Original
    2004 Volume 25 Issue 9 Pages 573-579
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.573
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    We report the control of surface dynamics of individual acetylene molecules on Pd(111) at 4.7 K, which involves (1) determination of adsorption sites of the molecules, and (2) inducing rotational and hopping motions of acetylene by excitation of specific vibrational modes through inelastic electron tunneling process. Topographic STM images of an acetylene molecule on the Pd(111) surface revealed that the molecule occupies the 3-fold hollow site as the most stable adsorption site. When the tunneling electrons were injected, the molecule rotated among three equivalent orientations with two threshold voltages at ∼150 mV (∼150 mV) and at ∼370 mV (∼280 mV) for C2H2 (C2D2), which correspond to C-C and C-H stretch modes. On the other hand, when the higher electron energy was applied, the molecule showed lateral hopping motion to the adjacent site in addition to rotational motion. The threshold was obtained at ∼370 mV (∼280 mV) for C2H2 (C2D2). The apparent energy dependence of the efficiency of the dynamic motions and the strong isotopic shift indicate that we can control the rotational and hopping motions by the excitation of specific vibrational modes of a single acetylene molecule.
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  • Step-edges and Catalytic Activity
    —Dissociation of H2S and CO on Ni(111)—
    Akihiko KITADA, Hidemi HIRASHIMA, Junya OGAWA, Haruhisa NAKANO, Taketo ...
    Article type: Original
    2004 Volume 25 Issue 9 Pages 580-585
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.580
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    The effect of step-edges on the dissociative adsorption of H2S has been studied on a Ni(111) surface using scanning tunneling microscopy (STM), Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). Exposure of Ni(111) to H2S at room temperature results in the formation of S islands with the structures of p(2×2) and reconstructed c(5√3×9) rect in the vicinity of step-edges. Subsequently, H2S dissociates on the terrace of Ni(111), leading to the formation of unique S species with a string structure. The STM observation indicates that the dissociation of H2S takes place on both step-edges and terraces. The dissociative adsorption of CO as well as formation of carbide islands also take place preferentially at the step-edges. It is thus suggested that a small amount of sulfur located at step-edges effectively deactivate CO dissociation in the methanation reaction.
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Current Topic
  • Effects of Light Intensity Distribution on Phase Modulated Excimer Laser Crystallization Characteristics
    Masayuki JYUMONJI, Yoshinobu KIMURA, Yukio TANIGUCHI, Masato HIRAMATSU ...
    Article type: Current Topic
    2004 Volume 25 Issue 9 Pages 586-593
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.586
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    Microtexture was analyzed for Si films crystallized by a phase-modulated excimer laser annealing method, using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Electron Back-Scattering Pattern (EBSP). Threshold fluences were identified for crystallization, lateral growth and film braking, by comparing the surface morphology and the microscopic excimer laser light intensity profile. It was found that {001} and {110} orientations are preferable for lateral growth direction but the surface orientation is random. A possible origin of preferable orientations for laterally grown film was discussed.
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Popular Science
  • Tasks in Organic EL Display Devices
    Yoshinori FUKUDA
    Article type: Popular Science
    2004 Volume 25 Issue 9 Pages 594-598
    Published: September 10, 2004
    Released on J-STAGE: May 18, 2008
    DOIhttps://doi.org/10.1380/jsssj.25.594
    JOURNAL FREE ACCESS
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    Organic Light Emitting Diode (OLED) devices have recently gained attention as one of the promising next-generation display devices because of their several excellent features compared with the others. The OLED device technology, which has a relatively short history, is still being developed and has many problems to be solved. Therefore, it is necessary to analyze the mechanism of deterioration phenomena of OLED in order to improve its performance and durability. However, the analysis of OLED devices has not progressed much yet because OLED has very weak and sensitive characteristics. Especially, research and analysis of the interface phenomena have not been sufficiently conducted. In this article, deterioration phenomena regarding interfaces of OLED devices will be introduced. Especially, the relation of operating lifetime and interfaces between organic material and anode or cathode, and the mechanism of dark spots generated and grow in OLED device are described.
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