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Shin-ichi NISHIZAWA, Masahiro HIRATA
2002 Volume 45 Issue 3 Pages
119-122
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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The Capacitance diaphragm gauge (CDG) is one of the most important vacuum gauges in low and middle vacuum ranges. The difference of temperature between the sensor head and the vacuum chamber gives a non-linear sensitivity of the gauge depending on the pressure due to thermal transpiration effect. Change in the sensitivity of about 4% between molecular flow regime and viscous flow regime is significant for metrological use of the gauge. In this study, by using a DSMC method, pressure distribution in the connecting tube of the gauge was obtained under the pressure range from molecular flow regime to viscous flow regime with taking account of temperature distribution along the connecting tube. It was in good agreement with the pressure dependence of sensitivity obtained by static expansion system experimentally. Furthermore, influence of gas-surface interaction on the thermal transpiration was also discussed.
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Minoru KARASAWA, Masahiro SAKAI, Keiji ISHIBASHI, Masahiko TANAKA, Ats ...
2002 Volume 45 Issue 3 Pages
123-126
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Large-area deposition with 1-m size is demonstrated by catalytic chemical vapor deposition (Cat-CVD) apparatus equipped with newly developed showerhead catalyzers. The arrangement of catalyzer wires is determined by simulation based on the experimental results that decomposed species on catalyzers are transported by isotropic thermal diffusion without an influence of the gas flow. Uniformity of± 7.5% and deposition rate of 5.3 Å/s for amorphous silicon films are obtained using silane flow rate of only 100 sccm on the glass substrate with a size of 960 mm ×400 mm. These results suggest that the Cat-CVD is one of the most promising methods for fabrication of large-area devices such as thin-film transistors and solar cells.
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Akiko N. ITAKURA, Tetsuya NARUSHIMA, Masahiro KITAJIMA
2002 Volume 45 Issue 3 Pages
127-129
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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We have observed a stress relaxation of a silicon oxide film made by plasma oxidation with the following nitridation. The radical nitridation reduces the compressive surface stress of the film expansion about 40-80%. This relaxation is larger than that of electron irradiation on the oxide film, which can reduce a disorder-induced surface stress. AES measurement shows the concentration of nitrogen does not precipitate on the SiO
2/Si interface but is uniform in the film and is only 3 atom.% in the film.
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Takemi UEKI, Shinji NAKAMURA, Minoru SHIONOYA, Shigeru NAKAJIMA, Naohi ...
2002 Volume 45 Issue 3 Pages
130-133
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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We analyzed the leakage current failure in the silicon (Si) on insulator devices. The failure sites were detected by light emission microscopy, and they were found to be tungsten (W) contacts. The cross section of the failed W contact was processed by focused ion beam, and it was observed by scanning ion and transmission electron microscopes. The defect goes the through active Si and buried SiO
2 layer from the buried W and arrives at the Si substrate. Our Auger electron spectroscopy analysis and energy-dispersive x-ray spectroscopy analysis identified that the defect included W, and that the active Si layer included a slight crystal defect. Our analysis suggests that the failure mechanism is over-etching of reactive ion etching (RIE) and a crystal defect of active Si layer. If the etching speed of the defective crystal is faster than the normal Si, a void is formed in the SiO
2 layer. Currently, the RIE process was improved, the crystal defect decreased, and the leakage current failure mode in the W contact decreased.
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Kenji OHKAWA, Takeo NAKANO, Shigeru BABA
2002 Volume 45 Issue 3 Pages
134-137
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Scaling analysis of the surface roughness has been performed on copper films prepared by DC magnetron sputter deposition. The deposition was performed at Ar gas pressures of 2 and 10 Pa. Under both pressures, deposition rates were almost the same and were 1.1 nm/s. Self-affine parameters α and β were determined from a series of AFM topographs of films deposited for various periods (30180 min). At 10 Pa, the roughness parameter α was 0.60.7 and the dynamical parameter β was 0.9, while at 2 Pa, where the surface roughness grew more modestly, α was 0.50.7 and β was 0.6. The difference also appeared in the correlation lengthξ. The correlation length became larger as the deposition proceeded at 10 Pa, in accordance with the roughness evolution theory. On the other hand, it stayed almost constant at 2 Pa. The effect of gas pressure on the surface roughness is discussed.
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Yoshio SONE, Hiroshi SUGIMOTO
2002 Volume 45 Issue 3 Pages
138-141
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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A model pumping system without a moving part, which makes use of thermal transpiration and is operated with its ends at an equal temperature, is constructed. The system consisting of ten units, each of which is a pipe of length 30 mm and inner diameter 15 mm with a simple inner structure and a heater, reduces the pressure of a reservoir of 8 × 10
3 cm
3 to a half in 200 sec when the other exit of the system is kept at a constant pressure between 10-40 Pa.
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Nobuhiko OTA, Toshikazu HAMAO
2002 Volume 45 Issue 3 Pages
142-144
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Outgassing rate of an epoxy resin is the most important property in application of an epoxy resin for semiconductor processing in a high vacuum environment. Main desorbed gases is H
2O from the surface and the inside of the epoxy resin.
Electroless plating process was improved by Cu and Ni plating and the impregnation of the epoxy resin on pre-etching process. Outgassing rate of the epoxy resin plated Cu and Ni layer was two orders of magnitude smaller than that of nonplated epoxy resin.
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Masao HASHIBA, Takahiro JINUSHI, Yuji YAMAUCHI, Yuko HIROHATA, Tomoaki ...
2002 Volume 45 Issue 3 Pages
145-148
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Gas permeability of SiC/SiC composite materials, which is one of the most important properties in application of SiC/ SiC composite for first wall and blanket of fusion reactors, was measured by using a vacuum apparatus. The cylindrical SiC/SiC composite specimens were prepared by three different processes. The measurement on permeability for three materials was carried out with helium gas pressure ranging from 10
2to 10
5 Pa at room temperature.
The pressure in bottom chamber down stream of specimens increased with the helium gas pressure within the applied pressure range. The helium gas flow through the material is regarded as molecular flow. The material made by PIP method showed the highest permeability. The lowest permeability was observed in the one made by PIP followed by RS method. The material, SA-TyrannoHex
TM made by hot pressing was in the second position. The difference of the permeability can be related with the macroscopic structure represented by pores and cracks.
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High Stored Current Issues
Ken-ichi KANAZAWA, Shigeki KATO, Yusuke SUETSUGU, Hiromi HISAMATSU, Ma ...
2002 Volume 45 Issue 3 Pages
149-152
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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For the KEK B-factory, an electron-positron collider which consists of two storage rings intersecting at the collision point has been running in operation since December 1998. The ring has a circumference of 3016 m, and its vacumm chambers are mainly made of copper. Untill July 2001, a fill with the initial current of 940 mA positron and 730 mA electron was established and the world record luminosity was achieved. Before the goal currents of 2.6 A positron and 1.1 A electron are achieved, the effect of high beam current has been emerging. The effect of electron cloud became evident especially in the LER. Some bellows were found to be warmed by the TE mode of beam induced fields. Direct damage by beam is seen at the surface of the movable mask. An indirect effect of the high beam current passing close to a vacuum seal is also observed.
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Yusuke SUETSUGU
2002 Volume 45 Issue 3 Pages
153-156
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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A non-linear dependence of vacuum pressure on the beam current has been observed in the KEKB positron ring. The behaviour changes by the bunch fill pattern, the bunch current and the external magnetic field. A simple simulation on the non-linear pressure rise is proposed assuming that the behaviour occurs by the electron multipactoring. The simulation well reproduces the observed non-linear pressure behaviours. Since the beam size blow up, which is also observed in the positron ring, is similar to the non-linear pressure rise, the results would support an explanation that the beam size blow up is related to the electrons in the beam chamber.
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Yusuke SUETSUGU, Tatsuya KAGEYAMA, Yasunao TAKEUCHI, Ken-ichi KANAZAWA ...
2002 Volume 45 Issue 3 Pages
157-160
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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The movable mask is a special device for an accelerator that cuts off spent particles near the beam orbit and reduces background of the detector. For the KEKB, an electron/positron collider with two rings, sixteen movable masks had been installed for each ring. The originally designed masks, however, revealed severe troubles of heating, arcing and vacuum leaks at the stored beam currents of several hundreds mA. Several kinds of improved masks had been designed employing RF technologies and were installed to the ring step by step. The latest masks are working well except for the grooves on the mask head. Here the problems of movable masks so far are summarized and the structures of the latest movable masks and their status are presented.
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Effect of a Carbon Divertor on Impurity Deposition
Yuko HIROHATA, Yuji NOBUTA, Yuji YAMAUCHI, Masao HASHIBA, Tomoaki HINO ...
2002 Volume 45 Issue 3 Pages
161-164
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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The third experimental campaign in large helical device (LHD) was carried out from June to December in 1999. In this campaign, graphite tiles were placed in the divertor region. To investigate the effects of the graphite divertor on plasma wall interactions, material probes were placed at the inner wall of vacuum vessel along the poloidal direction. As impurity species, Fe, Ni, Cr, C and O were observed in every sample. On the surface of the samples placed close to the plasma, Fe concentration was observed as high as 25 at.%. The deposition amount of Fe per one plasma discharge shot became approximately a half of that of second campaign. Carbon was largely deposited on the samples placed near to the graphite divertor and at the port. The thickness of deposited carbon was large, approximately 800 nm. Helium was retained in every sample. The amount of retained He strongly depended on the position of material probe in the LHD, i.e. the amount of He in the sample placed near plasma is larger than that on the port. It is indicated that the helium retention is mainly due to the helium glow discharge cleaning and during main discharge plasma. In the third campaign, metal impurities in the plasma were observed to be largely reduced by the use of graphite divertor. The plasma stored energy also increased by the reduction of metal impurity emission. In the present study, plasma material interaction based upon material probes contributed to a good plasma discharge performance.
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Masatoshi SATO, Konosuke INAGAWA, Hideo TAKEI, Hiroaki KAWAMURA, Yasuh ...
2002 Volume 45 Issue 3 Pages
165-168
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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The Build-up Process is very important in the production of a multilayer printed wiring board (PWB) in electric communication devices. Nowadays, laser and photolithography processes are the main methods used for forming via holes in the polyimide in the Build-up Process. In this study, as a preliminary experiment for via hole formation, etching rates in polyimides were investigated using a plasma etching process with a roll coater instead of previously utilized processes. This was carried out with a reactive ion etching (RIE) discharge, created by applying a low frequency power of 400 kHz to the main roller as a cathode, using O
2 and CF
4 gases. A high dynamic etching rate of 5 μm ·m/min was the target value. The dynamic etching rate increased with the power applied, and the maximum values obtained were 3 and 2 μm ·m/min for polyimide films (25 μm) of Kapton 100H and Upilex S, respectively. To realize a higher density of plasma, a high frequency power of 13.56 MHz was applied to the anode, from which the etching gasses were fed, in addition to the RIE discharge. The etching rate was found to further increase as a result. Moreover, adding N
2 gas to the etching gases increased the etching rate. These results taken together have created the possibility to surmount the target value.
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Tadashi NAKAMURA, Kunio OKIMURA
2002 Volume 45 Issue 3 Pages
169-172
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Plasma diagnostics in titanium (Ti) rf (13.56 MHz) magnetron sputtering were carried out using optical emission spectroscopy and atomic absorption spectrometry. Ti ions (Ti II) optical emission intensity in pure argon (Ar) discharge was compared with calculated optical emission intensity. Ti II absorption signal was obtained using absorption line of 336.1 nm, 337.3 nm, 338.4 nm (α
4F-
z4G°). The dependence of Ti II optical emission intensity on rf power and Ar pressure was also investigated.
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Takashi KUBO, Makoto TANAKA
2002 Volume 45 Issue 3 Pages
173-176
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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In this paper, the dependence of the surface conditions of the anode on the discharges was studied using the asymmetrical parallel plate radio frequency plasma reactor. In order to change the surface condition, aluminum foils were fixed on the anode made of stainless steel. In any cases, the one-dimensional distributions of the electron densities and plasma potentials were measured by using the self-compensated Langmuir probe.
The results indicate that the change of the anode surface influences the spatial distribution of electron density near the cathode.
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Hiroshi TSUJI, Hiromitsu SUGAHARA, Tomohiko SAGIMORI, Masanori MOTONO, ...
2002 Volume 45 Issue 3 Pages
177-180
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Photocatalytic properties of Cu negative-ion implanted TiO
2 (rutile) were investigated as well as light absorption properties due to surface plasmon resonance of Cu nanoparticles in TiO
2. Cu negative ions were implanted into TiO
2 at 50 keV and also catalytic efficiencies were measured by decolorization method of methylene blue solution. After thermal treatment at 400°C, implanted sample showed an optical absorption peak at a photon energy 1.9 eV. This photon energy of absorption peaks well agreed with an estimate value of surface plasmon resonance calculated by Mie's theory with n = 2.71. In the catalytic test with methylene blue under irradiation of a fluorescent light, Cu-implanted rutile (50 keV, 7 × 10
16 ions/cm
2, 400°C annealed) showed 1.8 times the catalytic efficiency of the unimplanted rutile.
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Hideaki KASAI, Hiroshi NAKANISHI, Tomoya KISHI, Fumio KOMORI, Ayao OKI ...
2002 Volume 45 Issue 3 Pages
181-183
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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We investigate the magnetic properties of atom bridges, made of Fe and Ni, between a scanning-tunneling-microscope tip and a solid surface, within the density functional theory. We consider a twisted ladder atom bridge of an Fe
1-αNi
α On the basis of the numerical results, we show the atomic structure and magnetic properties of the bridge as we increase α.
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Ippei OHKUBO, Hideaki HARADA, Takeshi MIKAYAMA, Naohisa INOUE
2002 Volume 45 Issue 3 Pages
184-187
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Nitrogen doping has attracted much attention because it reduces secondary defects. It is important for clarification of this reduction mechanism and for nitrogen concentration measurement to reveal the nitrogen configurations and the origin of infrared absorption bands. In this paper, the atomic-level behavior of around nitrogen is revealed by using molecular orbital method and valence force method. We clarified normal vibration of interstitial nitrogen pair, nitrogenvacancy complexes and nitrogen-oxtgen complexes.
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Takahiro OTSUKA, Yasushi YAMANO, Shinichi KOBAYASHI, Toshiyasu HIGO, N ...
2002 Volume 45 Issue 3 Pages
188-191
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Vacuum breakdown characteristics of oxygen-free copper electrodes processed by precision machining were investigated by applying impulse voltage. Before breakdown measurements, He ion-beam sputtering was performed to the electrode surface. Chemical compositions on the electrode surface before and after the ion-beam sputtering and after the 500 times repetitive breakdowns were analyzed by X-ray Photoelectron Spectroscopy (XPS). In addition we investigated the vacuum breakdown characteristics of oxygen-free copper electrodes that ware processed by precision machining and heated in the hydrogen firing. As a result, processed electrodes by precision machining showed higher breakdown fields than those for electrodes without the process. And their conditioning saturated rapidly. The results of the XPS spectra confirmed that organic contaminants due to C were removed by repetitive breakdowns. The hydrogen firing improved breakdown fields of the early stage of conditioning process.
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Toshinobu NAKAJIMA, Kenichi SHUDO, Tetsurou SHIRAO, Yoshihito TANAKA, ...
2002 Volume 45 Issue 3 Pages
192-195
Published: March 20, 2002
Released on J-STAGE: April 23, 2010
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We constructed the very sensitive pulsecount-detector system to study the desorption from semiconductor surface in the ultra-high vacuum. We show the results of thermal desorption from Br/Si (111). According to thermal desorption spectroscopy, three peaks are identified in the SiBr2 (187.8 amu) spectra. From the time-course of the isothermal desorption yield as a function of time, the peak at 950 K is turned out to be of the 2nd order, and from its tempereture dependence it exhibits 2.2 eV of the potential barrier. The barriers of the peaks at 800 K and at 600 K are 0.3 ± 0.1 eV and 0.5 ± 0.1 eV, respectively.
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Yujiro FUKUI, Yosuke SAKAMOTO, Masaaki AONO, Keishi WATANABE, Shozo HO ...
2002 Volume 45 Issue 3 Pages
196-199
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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In order to understand the fundamental character for forming Ba
3N on Si (111) surface, the following two studies have been carried out by means of Low Energy Electron Diffraction (LEED), and Auger Electron Spectroscopy (AES) and Ultraviolet Photoemission Spectroscopy (UPS). 1) Whether silicon nitride layer would be accepted as a diffusion barrier between Ba and Si layer was examined. Ba and Si atoms formed a compound layer above 400 degree Centigrade, so that the silicon nitride layer was disqualified as a diffusion barrier between Ba and Si layer. 2) The electronic states in the coadsorption of Ba and NH
3 on Si (111) surface were investigated. When less than 2 MLs Ba adsorbed Si (111) surface was exposed to NH
3, the electronic states of Ba-N, N-H, and the lonepair electron pair of NH
3 appeared, and when more than 2 MLs Ba adsorbed Si (111) surface was exposed to NH
3, the electronic states of Ba-H appeared in addition to three electronic states mentioned above.
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Takeshi INAOKA
2002 Volume 45 Issue 3 Pages
200-203
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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High-resolution electron energy-loss spectroscopy (HREELS) is a powerful tool for observing an energy dispersion of low-energy surface excitation modes. In the specular-reflection geometry (SRG), a probed dispersion region determined kinematically depends upon the incident angle θ
0 and the incident energy
E0, while, in the off-specular geometry (OSG) it depends upon θ
0 and a scattered angle θ
S adjusted by the analyzer position. With change in θ
0 and
E0 in the SRG and with change in θ
0 and θ
S in the OSG, we make a kinematic analysis of the probed dispersion region with special attention to its width. Our analysis shows that, with a grazing angle θ
0 fixed and with
E0 or θ
S varied, we can scan a sharply narrowed probed region on a wave number-angular frequency (
Q-ω) plane to make an accurate observation of the energy dispersion of surface-excitation modes. An incident electron undergoes an image force, when it incidents on a surface of dielectric material. However, the image force is found to exert no substantial influence on the probed region even at grazing incidence.
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Akitaka YOSHIGOE, Yuden TERAOKA
2002 Volume 45 Issue 3 Pages
204-207
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Employing Si-2p and O-1s photoemission spectroscopy using monochromated synchrotron radiation and the supersonic molecular beam technique, we have performed “
real time”
in situ observations of oxidation states on the Si (001) -2×1 surface at room temperature. High-resolution Si-2p photoemission spectra, which unambiguously resolve components for oxidation states [Si
1+, Si
2+, Si
3+ and Si
4+], were successfully measured requiring only 43 sec per spectrum. We found that the Si
4+ species gradually increased to reach the oxide thickness of 0.57 nm just after the saturation of Si
1+, Si
2+ and Si
3+ species with a translational energy of 2.9 eV.
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Tomoyuki KIMURA, Yoshifumi AOI, Eiji KAMIJO
2002 Volume 45 Issue 3 Pages
208-211
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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TiN/CN
x and ZrN/CN
x multilayered thin films were deposited on Corning#7059 glass substrates by a dual ion beam sputtering (IBS) system with an Ar ion source for sputtering the target and a N
2 ion source for bombarding the substrate. The multilayered thin films were deposited by alternately sputtering Ti or Zr and C targets. Total film thickness was 400 nm and multilayered period λ changed from 5 to 160 nm. The properties of the multilayered thin films were examined by X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), Knoop indenter, and the internal residual stress of the multilayered thin films were examined by multi-beam optical sensor (MOS).
The low angle XRD patterns of the both multilayered thin films exhibited a characteristic of long-range modulation structure. TiN/CN
x multilayered films consisted from microcrystalline TiN and amorphous CN
x exhibited an increasing of TiN crystallization and a strong TiN (200) preferred crystal orientation. The deposited multilayered thin films indicated a maximum value in hardness and the large internal residual stress generation in a function of the multilayered periods λ.
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Yasuhito GOTOH, Nobumasa KIWA, Hiroshi TSUJI, Junzo ISHIKAWA
2002 Volume 45 Issue 3 Pages
212-214
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Transition metal carbide thin films were prepared by radio frequency magnetron sputter deposition. The target used was hafnium carbide and tantalum carbide, and sputtering was taken place by argon gas discharge. It was necessary to adjust the sputtering condition, in order to obtain carbide films, otherwise the resultant films contained much oxygen. Higher gas pressure and lower input power gave almost stoichiometry carbide films for tantalum, whlie the condition was not still appropriate for hafnium. We have evaluated crystallinity and work function of the deposited films.
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Yasuhito GOTOH, Hidenori KITAI, Hiroshi TSUJI, Junzo ISHIKAWA
2002 Volume 45 Issue 3 Pages
215-218
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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The orientation of the niboium nitride thin films was controlled by the assisting ion energy and its incident angle to the substrate in ion beam assisted deposition technique. The films were deposited under the different ion incident angle and ion energy, and their orientation was evaluated by x-ray diffraction. The work function was also measured by Kelvin probe. As a result, it was found that the c-axis of the crystallites were grown along the direction perpendicular to the ion incident angle. The tendency was more prominent when the ion energy was increased. However, the difference in the work function among the deposited samples was not large, probably due to the fact that the films were still polycrystaline.
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Yoshifumi AOI, Eiji KAMIJO
2002 Volume 45 Issue 3 Pages
219-222
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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B-C-N thin films were deposited onto Si (100) substrates by pulsed laser deposition (PLD) using B
4C target under nitrogen radical beam irradiation. The deposited films were characterized by x-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The compositions of the films were almost B
45C
25N
25. FT-IR and XPS spectra indicate existence of B-C and C-N bonds as well as that of B-N and C-C bond within the films deposited at room temperature. Phase separation into graphite and h-BN was observed in the film deposited at high temperatures.
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Kazuaki TSUDA, Naoto KIKUCHI, Eiji KUSANO, Hidehito NANTO, Akira KINBA ...
2002 Volume 45 Issue 3 Pages
223-226
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Polytetrafluoroethylene (PTFE) /Al or Ti multilayered films have been deposited in order to investigate effects of interfacial energy on internal stress and hardness. The total thickness of the multilayered films was fixed at 200 nm. Modulation period of the multilayered films was changed from 6.6 nm to 200 nm. Internal stress within metal layers was estimated from strain obtained by X-ray diffraction measurements. Hardness of films was measured by a nano-indentation method. Internal stress observed is compressive and increases with decreasing modulation period. The maximum of internal stress was approximately 10 times larger than that calculated from the value of the accumulated interfacial energy. The hardness also increases with decreasing modulation period. The decrease in the hardness shows a good agreement with the increase in the internal stress. It is concluded that the hardness enhancement strongly relates to the increase in internal stress in PTFE/metal multilayered films.
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Nobuo SAITO, Isamu NAKAAKI, Hiromu IWATA, Shoji YOSHIOKA, Tomuo YAMAGU ...
2002 Volume 45 Issue 3 Pages
227-230
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Amorphous SiCS : H : F films have been deposited by a reactive rf magnetron sputtering of Si target in Ar-CH
4 and SF
6 gas mixtures. The effects of SF
6 partial pressure ratio
R on the electrical and optical properties of the films were investigated.
With increasing
R, sulfur-related bonding configuration can be observed. The photoconductivity shows a maximum below
R= 20%, whereas the optical bandgap almost unchanges and the dark conductivity increases slightly. These data imply that S atoms may relax the disordered structure as well as acting as dopants in this range of
R.
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Isao NAKAMURA, Ichiro TAKANO, Yoshio SAWADA
2002 Volume 45 Issue 3 Pages
231-234
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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The photocatalytic properties of Cr-doped TiO
2 films was investigated by the immersion test in a methylene blue solution under UV light irradiation. The Cr/TiO
2 films were prepared as follows; after TiO
2 film was prepared on a slide glass substrate by He
+-ion beam assisted reactive deposition method (He
+-IBARD), Cr was doped into TiO
2 films by Ar
+-ion beam assisted deposition method (Ar
+-IBAD).
In the Ar
+-IBAD method, Ar
+ ion irradiation was carried out during Cr evaporation in order to form the mixing layer of Cr and TiO
2. Ar
+ ions played an important role to knock on Cr atoms into TiO
2 film. The rate of absorbance change for blank of Cr/TiO
2 film showed higher value than that of TiO
2 film under UV light irradiation. In order to improve photocatalytic properties of Cr-doped TiO
2 films, it was required that doped-Cr showed the metal state and amorphous structure.
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Taro YAKABE, Yoshikazu TERAI, Syuma YASUZUKA, Chieko TERAKURA, Taichi ...
2002 Volume 45 Issue 3 Pages
235-238
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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The electrical conductivities of Co thin films with the thickness in the range 2.530 nm have been studied. In the low temperature region, the sheet conductivities for the films of 3.05.0 nm show logarithmic temperature dependence. The dependence is interpreted by the electron-electron interaction effect rather than the weak localization effect. The coefficient of the logarithmic behavior is found to be suppressed as the thickness decreases, which may be interpreted in terms of the percolation effect.
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Akio SUZUKI, Takeshi MITSHUHASHI, Hirohisa OKUSHIMA, Kazuyoshi IKEDA, ...
2002 Volume 45 Issue 3 Pages
239-242
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Iron disilicide (β-FeSi
2) thin films were deposited on Si (001) substrate by a pulsed laser deposition using an ArF excimer laser of high power. The film compositions were varied by changing the ratio (trace ratio) of the time required to irradiate each side of the split target made of silicon and iron. It was confirmed from Hall effect measurement that the conduction type of the film changed from p type to n type when the trace ratio varied from 3.2 to 4. From XRD spectra of these films, peaks of β-FeSi
2 (422) and (800) were identified. It was found from FE-SEM and AFM observations that the β-FeSi
2 films with small surface roughness (Ra =7.36 nm) were obtained and there were little droplets on the film surfaces.
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Akio SUZUKI, Akihito MORI, Jun SAKAMOTO, Yoshiyuki TANI, Takanori AOKI ...
2002 Volume 45 Issue 3 Pages
243-246
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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In
2O
3 doped with 5 wt% SnO
2 (indium-tin oxide (ITO) (5 wt%)) films were deposited on glass substrates by pulsed laser deposition using an ArF excimer laser (λ= 193 nm). In all experiments, repetition rates of 150 Hz, the energy density of 6 J/cm
2, and an ablation time of 30-900 sec were used. A lowest resistivity of 8.45 × 10
-5 Ω ·cm and an optical transmittance of more than 80% in the visible range of the spectrum were obtained for ITO (5 wt%) films of approximately 300-nm thickness fabricated at a substrate temperature of 400°C and oxygen pressure of 10 Pa. Smooth surfaces with an average surface roughness of 1.26 nm were observed by field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM).
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Takanori AOKI, Shin AKIDUKI, Akio SUZUKI, Tatsuhiko MATSUSHITA, Masahi ...
2002 Volume 45 Issue 3 Pages
247-250
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Thin films (of 50 nm thick) with a stacked structure (of 10150 layers) of In
2O
3 and ZnO have been deposited onto the glass and the polycarbonate substrates using the split target consisting of In
2O
3 and ZnO by a pulsed laser technique with an ArF excimer laser. A relation of the transmittance change ΔT at the wavelength of 400 nm between the annealed state (480°C × 20 min) and the as-deposited state versus the number of layers for the structure fabricated at the trace ratio of In
2O
3 : ZnO = 1 : 1 was obtained. The structure with 20 layers showed the maximal value of ΔT. SEM observation revealed that the surfaces of these films were enough smooth to use in static or revolution tests for'write'. AFM observation showed that surface roughness of the as-deposited state and the annealed state were Ra of 0.76 nm and Ra of 2.25 nm respectively. A peak power dependence of CNR of 3T signal (λ = 406 nm, NA = 0.65) at a linear velocity of 5 m/s and a read power of 0.6 mW was measured for the disk samples with 60-layers fabricated for the revolution tests. That the write power of less than 3 mW was required and maximal value of CNR = 67 dB was obtained. The values of CNR could be improved by optimizing the number of layers and the film compositions.
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Yasuyuki ITO, Hiroyuki NAKANO, Yoshiyuki UCHIDA, Goro SAWA, Kenzo KOJI ...
2002 Volume 45 Issue 3 Pages
251-254
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Vanadyl-Phthalocyanine (VOPc) thin films are prepared by a molecular beam epitaxy on KCl substrate. The nonlinear optical properties, VOPc molecular orientation and growing mechanism on KCl substrate of VOPc thin film are investigated with UV/VIS spectra, the images observed by SEM and AFM and the second-order harmonic (SH) and third-order harmonic (TH) intensities measured by Maker-fringe. The VOPc thin film treated with a thermal treatment changes from pseudo-epitaxy to epitaxy. Moreover, the surface of the thin film is a plate-like-crystal and smooth. These suggest that the VOPc molecules on KCl substrate are parallel to KCl substrate. The SH and TH intensities of VOPc thin films are increased with thermal treatment. It is closely related to the phase-morpholpgy of VOPc thin film. Therefore, the VOPc thin film epitaxially grown improves the SH and TH intensities.
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Koji TAMURA
2002 Volume 45 Issue 3 Pages
255-257
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Intensity distributions of a neodymium ion beam, which was extracted from a laser photoionized plasma were measured by scanning a multichannel Faraday cup. The lateral width of ions at the position of the Faraday cup was broad without any concentric electric field, and it was reduced by an application of a concentric potential produced using a pair of semicylindrical electrodes set outside the extraction electrode. The ion beam was further collimated by the electric field produced using a pair of semispherical electrodes. The central ion beam intensity with these electrodes was increased about 36 times compared without additional electric field. The results were useful for applications of laser photoionized ion beams.
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Hiroko KAJI, Kiminori KAKITANI, Yoichiro YAGI, Akio YOSHIMORI
2002 Volume 45 Issue 3 Pages
258-261
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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The recent results of electron energy loss spectroscopy (EELS) reveal vibrational states totally different in character for Ni (111) 1× 1-H and Ni (111) 2 × 2-2H surface. Those results indicate that the vibrationally excited states of hydrogen atoms on Ni (111) 2 × 2-2H can be delocalized. To clarify the nature of the hydrogen vibration on the Ni (111) surface, the adiabatic potential surfaces for a hydrogen atom on Ni (111) 1 × 1-1H, Ni (111) 2 × 2-1H, Ni (111) 2 × 2-2H and Ni (111) 2 × 2-4H are calculated, respectively, by the first principles calculation based on the density functional theory (DFT). The obtained vibrational states are consistent with experimental results. The Monte Carlo simulation with the lattice gas model and the tight binding model expects the formation of a surface vibrational band of excited states on this system for small coverage of Hydrogen.
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Yusuke FUJIOKA, Takafumi SATOH, Syouji TAKAGI, Tetsuji GOTOH
2002 Volume 45 Issue 3 Pages
262-264
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Diffusion of hydrogen into a bulk of molybdenite crystal that is exposed to hydrogen gas is studied by measurement of gas emitted from a bulk crystal during cleavage experiment. The cleavage experiment is performed to observe the change of hydrogen concentration in the bulk by the sample heating. The experiment shows that amount of emitted hydrogen molecules and water reduces but emitted hydrogen atoms do not reduce much when the molybdenite crystal heated at 300°C is cooled to room temperature. This suggests that hydrogen molecule adsorbed dissociatively on the surface, and then the hydrogen atoms diffuse into the molybdenite crystal.
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Yasuhiro YAMAUCHI, Yoshiyuki MIZUNO, Akihiro TANAKA, Teiichi HOMMA
2002 Volume 45 Issue 3 Pages
265-268
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Dynamical behaviors of hydrogen molecules from titanium oxides on a titanium surface were examined with thermal desorption spectroscopy (TDS). The oxide film on a titanium surface has been formed in an oxygen gas with a pressure of 1 × 10
-4 Pa at a temperature of 400°C. The specimen was exposed in a hydrogen gas at a pressure of 1 × 10
4 Pa after the oxidation. The TD spectra of hydrogen from the titanium oxide surface have shown three peaks.
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Kunihiro NOBUHARA, Hideaki KASAI, Hiroshi NAKANISHI, Ayao OKIJI
2002 Volume 45 Issue 3 Pages
269-272
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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The absorption of hydrogen into Pd (111) is investigated. In particular, hydrogen-induced relaxation of the Pd lattice and its role in hydrogen absorption into the surface are studied. The potential energy curves (PECs) for the hydrogen motion on a frozen lattice surface and on a hydrogen-induced relaxed lattice surface are calculated within the density functional theory. From the calculated results, it can be seen that the energy barrier for hydrogen atom absorption takes the lowest value at an fcc hollow site on the frozen lattice surface. Furthermore, the barrier is lowered by the relaxation of the Pd lattice.
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Dai MOTOJIMA, Yuko HIROHATA, Tomoaki HINO, Seio SENGOKU
2002 Volume 45 Issue 3 Pages
273-276
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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For vanadium alloy, Ti-O coating was made by a reactive sputtering in order to reduce hydrogen absorption. After the annealing of vanadium alloy with Ti-O film in vacuum, the atomic composition and film thickness were examined by Auger electron spectroscopy. Both the atomic composition and film thickness remained the same after the annealing with a temperature lower than 773 K. The vanadium alloy with Ti-O film was exposed to hydrogen gas environment at 573 K, and then the hydrogen absorption rate was measured. In this measurement, the film thickness of the sample was changed. The hydrogen absorption rate decreased with increase of the film thickness when the thickness was less than approximately 0.5μm. In the case that the film thickness was 0.5μm, the absorption rate was approximately 50 times reduced, compared to the case without the coating.
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Masaaki AONO, Yujiro FUKUI, Toshio URANO, Kaoru OJIMA, Masamichi YOSHI ...
2002 Volume 45 Issue 3 Pages
277-280
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Adsorbed structures of Ba on Si (111) surfaces have been investigated by LEED (Low Energy Electron Diffraction) and STM (Scanning Tunneling Microscopy). We compared the vicinal substrate surface with the flat substrate surface of which the inclination from the (111) plane is small in order to confirm whether the step arrangement is caused by the proper miscut angle of substrate. On the vicinal Si (111) surface, one-dimensional 10×1 structure was observed by LEED and the step arrangement of 10-times the unit length terraces with a double-layer step height has been observed by STM after annealing at about 950°C. On the flat Si (111) surface, 3 domains of 5×1 have been observed in the same temperature range by LEED and STM. It was confirmed that the step arrangement was caused by a cooperation of a proper miscut angle of the substrate and the superstructure on the terrace.
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Hiroki MINODA
2002 Volume 45 Issue 3 Pages
281-284
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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DC and AC parallel heating procedure was applied for quantitative study of in-phase step wandering instability on a Si (111) 1×1 vicinal surface induced by electromigration of Si adatoms. In-phase step wandering is one of the step instability where steps wander in-phase without changing step-step distance.
By controlling dc component of heating current (or applied field) and temperature individually, dc current (or dc field) and temperature dependences of the period of the in-phase step wandering on the Si (111) 1×1 vicinal surface were investigated. Temperature dependence of an effective charge of Si adatoms on a Si (111) -1×1 surface was evaluated and at about 1270 K the effective charge is approximately 0.02 and it linearly decreases with temperature.
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Miki OMOTE, Goro MIZUTANI
2002 Volume 45 Issue 3 Pages
285-288
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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We have measured SH intensity from SiO
2/TiO
2 (110) and TiO
2 (110) for the photon energy from 2
hω = 3.65 eV to 4.68 eV. We have found that the SH intensity from SiO
2/TiO
2 (110) is several times higher than that from TiO
2 (110) probably due to a resonance of some electronic level at the SiO
2/TiO
2 (110) interface.
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Shigeki MIZUSHIMA, Masaaki UEKI
2002 Volume 45 Issue 3 Pages
289-292
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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In order to improve the stability of mass standards, it is necessary to estimate the amount of the water adsorption on the surface of a weight. In this report the physical adsorption of water molecules on a stainless steel weight was measured using an ellipsometer. The variations in the physical adsorption was determined to be in the range from 0.022μg/cm
2 to 0.036μg/cm
2 for the change in the relative humidity from 0.8% to 45%. The sensitivity used for this calculation was estimated using a five-medium model consisting of air, water adsorption layer, oxide layer, surface roughness, and substrate.
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Keita TSUJI, Kuei-Yi LEE, Keiichi FUJIMOTO, Shigeharu OHKURA, Shin-ich ...
2002 Volume 45 Issue 3 Pages
293-296
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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We have succeeded in controlling density and diameter of the carbon nanotubes (CNTs) prepared by RF magnetron sputtering. The catalytic Ni particles on the substrates were prepared by dipping the Ni film on the substrates into hydlofluoric acid (HF). The density and diameter of the particles were changed with varying HF treatment times. There was correlation between the particle size and the nanotube diameter. The particles could be working as nucleation seeds of carbon nanotubes.
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Kosuke MATSUMOTO, Mitsuru OGURA, Koji KATSURAHARA, Satoru KISHIDA, Tak ...
2002 Volume 45 Issue 3 Pages
297-300
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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We prepared Bi
2Sr
2Ca
n-1Cu
nO
y (BSCCO) thin films by RF magnetron sputtering using a mixture of He + O
2 sputtering gas (He : O
2= 4 : 1). As helium gas effectively generates active particles of O
2+ and O
+ by the Penning ionization effect, the crystallinity of the films is expected to improve.
The crystallinity and the composition of films were dependent on the composition of targets. When we prepared the Bi -2212 films using the targets of Bi : Sr : Ca : Cu = 2 : 2 : 1 : Z (Z = 1.0-3.0), the best crystallinity of the film was obtained using the target of Z = 2.0. Furthermore, we prepared the Bi-2223 films with the composition of target, Bi : Sr : Ca : Cu = 2 : 2 : 2 : 3. The films with dominant Bi-2223 single phase were obtained only at
Tsub = 630°C, but Bi-2223 and Bi-2212 mixed phases appeared at the other substrate temperatures.
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Kazuto KOIKE, Takanori TANITE, Takayoshi HONDEN, Hi-izu OCHI, Shigehik ...
2002 Volume 45 Issue 3 Pages
301-304
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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It has been difficult to obtain single crystalline ZnO films on Si substrates due to the oxidation of Si surface during initial ZnO growth. In this letter, we report the growth of single crystalline ZnO films on Si (111) substrates using a buffer layer of CaF
2. The films were grown by radical source molecular beam epitaxy, and revealed by x-ray diffraction to be in the c-axis orientation without in-plane rotational domains. An ultraviolet photoluminescence corresponding to the bandgap energy was dominant for the films even at room temperature. It is indicated by the results that the use of CaF
2 buffer layer is promising for the growth of high-quality ZnO (0001) films on Si (111) substrates.
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Teruyuki DEISHI, Hideo OKAYAMA, Akiyoshi NAGATA
2002 Volume 45 Issue 3 Pages
305-308
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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Solid oxide fuel cell (SOFC) having a three-layer film of Ni/YSZ/Ni structure with 20-40μm was prepared on the porous Al
2O
3 substrate by RF magnetron sputtering. The structural and electrical properties of the YSZ electrolyte and Ni electrode films were investigated for various layer thicknesses. Ni electrode film grown at an RF power of 300 W indicated the columnar structure and resistivity of the film decreased with increasing layer thickness. Although conductivity of a SOFC having a three-layer film grown on the Al
2O
3 substrate increased with increasing layer thickness, its value was reduced by two order compared with theoretical one, because YSZ electrolyte was deformed to structure with many pores by the thermal energy.
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Yasuhito GOTOH, Nobumasa KIWA, Hiroshi TSUJI, Junzo ISHIKAWA
2002 Volume 45 Issue 3 Pages
309-312
Published: March 20, 2002
Released on J-STAGE: October 20, 2009
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We have prepared hafnium and tantalum nitride thin films by magnetron sputter deposition and evaluated their properties. Unlike the common preparation method of the nitride, that is, reactive sputtering, we adopted the direct sputtering of nitride target by pure argon plasma. The nitrogen concentration of the films was approximately the same with the target for hafnium nitride, but was slightly lower than the target for tantalum nitride. The film properties such as crystallinity and work function was measured.
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