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Katunobu ISHIZAWA, Takeru NOMURA, Akihisa SHIMADA, Minoru KANAZAWA, Sa ...
1998 Volume 41 Issue 3 Pages
91-95
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Chemical polishing (CP) is advantageous for low-cost polishing of metallic objects with complex shapes. But conventional CP has not been sufficiently developed to be applied to materials used in ultrahigh vacuum (UHV) and extremely high vacuum (XHV) systems. Therefore, we developed a CP process optimized for application to UHV and XHV materials that uses a solution of phosphoric and nitric acids and an additional cleaning process. Using this optimized CP process, the degree of outgassing of chemically polished aluminum is comparable to the outgassing achieved with special extrusion and ethanol lathing processes. This optimized CP process can be used for regular surface treatment of aluminum alloys used in both UHV and XHV chambers and related equipment.
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Sakae INAYOSHI, Kazuya SAITO, Yukie SATO, Sonoko TSUKAHARA, Yasuhiro H ...
1998 Volume 41 Issue 3 Pages
96-99
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Chemical polishing (CP) was selected to develop a practical surface treatment of stainless steel that will be generally used in ultrahigh vacuum (UHV) technology because CP can treat materials wholly in any shape at the final step of parts fabrication process.
Using short samples of SUS304L stainless steel the solution and the polishing condition were optimized from outgassing rate and reproducibility. The polished surfaces were characterized by Auger electron spectroscopy (AES), scanning electron microscopy (SEM), and Atomic force microscopy (AFM).
The chemically polished (CP) chamber was compared with those treated by conventional electrolytic polishing (EP) and glass beads blasting (GBB). In pump-down curves, the outgassing rate of CP samples was the same as that of EP one and 10% of GBB one. At the ultimate pressure at 28°C after 150°C × 20 h baking the outgassing rate of the three chambers with different surface treatments showed a same value, 1 × 10
-9 Pa·m·s
-1.
The technical purpose to use the CP for UHV material surface treatment is satisfied by this result and the cost of CP is less than that of EP because it doesn't need electricity.
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Takeshi SOUMA, Hiroshi MATSUDA
1998 Volume 41 Issue 3 Pages
100-103
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Outgassing rate is essential data for designing a vacuum chamber for ultra high vacuum (UHV) and extreme high vacuum (XHV). In order to choose the best surface condition, we fabricated seven chambers with different surface treatment, material and pre-baking temperature and measured their outgassing rate by through-put method. We also analyzed each surface composition by Auger electron spectroscopy (AES) to discuss the relationship between outgassing rate and surface composition. The principal results are as follows. (1) The difference in surface treatment does not show a significant effect on outgassing rate. (2) Outgassing rate of type 304 stainless steel is as same as that of type 316. (3) Pre-baking at 450°C is the best condition to increase Cr content on the surface. (4) The higher Cr content leads to the lower outgassing rate after baking at 200°C in 72h.
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Katsuto TANAHASHI, Naohisa INOUE, Yusuke MIZOKAWA
1998 Volume 41 Issue 3 Pages
104-107
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Radial distribution of oxidation-induced stacking faults (OSF) and cavities and its dependence on growth rate are discussed. The nonequilibrium incorporation of oxygen and vacancy, consumption of vacancies by cavities formation and oxide precipitates nucleation enhancement by vacancies are considered to discuss them.
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Katsuto TANAHASHI, Yuichi KAWAMURA, Naohisa INOUE, Yoshikazu HOMMA
1998 Volume 41 Issue 3 Pages
108-110
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Surface roughening processes in the molecular beam epitaxy growth of GaAs are studied by in-situ scanning electron microscopy. Three types of onset of three dimensional growth, pure 3D growth, coexistence of 3D and 2D growth, and 2D to 3D transition are observed.
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Yasunobu KURODA, Masaru KITAGAWA, Akishige SATO, Eiji KUSANO, Akira KI ...
1998 Volume 41 Issue 3 Pages
111-114
Published: March 20, 1998
Released on J-STAGE: January 30, 2010
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A technique to enhance adhesion of hard coatings to substrate by using compositionally gradient interlayers has been applied for TiN/Ti/TiO
2 and ZrN/Zr/ZrO
2 multi-compositional coatings. The coatings were prepared by dc reactive magnetron sputtering using a Zr or a Ti Target. Adhesion of coatings to a borosilicate glass substrate was estimated by a scratch method. The hardness of coatings was measured by a nano-indentation method. Without a underlayer, ZrN coatings showed very poor adhesion. By using compositionally gradient underlayers, the adhesion strength of ZrN hard coatings was enhanced drastically up to adhesion strength values almost equal to oxide singlelayer coatings. The increase in hardness by inserting compositionally gradient underlayers was observed in ZrN/Zr/ZrO
2 system.
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Masaru KITAGAWA, Akishige SATO, Yasunobu KURODA, Eiji KUSANO, Hidehito ...
1998 Volume 41 Issue 3 Pages
115-118
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Ti-TiN multilayer films with thickness of 400 nm were deposited on TiO
2-Ti underlayers on borosilicate glass substrate by changing N
2 flow rate periodically in dc reactive magnetron sputtering. Composition of Ti-TiN multilayer films was measured by XPS. Hardness of Ti-TiN multilayer films was measured by a nano-indentation method. By XPS analysis, it was found that multilayer films consisted of repeated Ti
0.7N
0.3Ti
0.55N
0.45 layers and that the binding energy of Ti shifted toward high energy as nitrogen contents increased. Hardness was found to depend on the modulation period, yielding the maximum of 28.7 GPa at the modulation period of 20 nm. We concluded that the hardness enhancement obtained was caused by both changes in the number of interfaces penetrated during a nano-indentation and an interaction between the two layers with different mechanical properties.
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Hiroyuki EIKI, Hideto YANAGIHARA, Yuko HIROHATA, Tomoaki HINO, Kazuhir ...
1998 Volume 41 Issue 3 Pages
119-122
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The hydrogen retention properties of pure boron and oxidized boron films were evaluated by both the change of pressure during hydrogen glow discharge and thermal desorption spectroscopy (TDS). After hydrogen loading by glow discharge the absorption amount of hydrogen for the oxidized boron film was 20-30% smaller than that of the pure boron film. This result was almost consistent with that of TDS measurement. The concentration of oxygen at the top surface for the pure boron and the oxidized boron film was 5 at.%, 35 at.%, respectively. No change of the oxygen concentration for the oxidized boron film was observed.
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Koh KANAYA, Yuji YAMAUCHI, Yuko HIROHATA, Tomoaki HINO, Kintaro MORI
1998 Volume 41 Issue 3 Pages
123-126
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Hydrogen retention properties of Li films and lithium oxide-lithium hydroxide (Li
2O-LiOH) mixed films were investigated by two methods, hydrogen ion irradiation and hydrogen glow discharge. In a case of the hydrogen ion irradiation, thermal desorption spectrum of hydrogen retained in Li
2O-LiOH film had two desorption peaks at around 470 K and 570 K. The ratio between retained hydrogen and Li atom was about 0.7.
In a case of the hydrogen glow discharge, the hydrogen was also gettered in Li film during the discharge. The ratio of H/Li was almost 0.9. Most of gettered hydrogen desorbed by a baking with a temperature of 370 K. On the contrary, when the Li film exposed to the atmosphere was irradiated by the hydrogen plasma, the desorption of H
2O was observed in addition to the adsorption of H
2.
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Yuko HIROHATA, Miharu OKEGAWA, Hideto YANAGIHARA, Tomoaki HINO, Norio ...
1998 Volume 41 Issue 3 Pages
127-130
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Gas desorption properties of various tungsten-coated graphite materials used in a fusion reactor were investigated by using a technique of thermal desorption spectroscopy. Tungsten-coated graphite with a rhenium interlayer (W-Re/C) was prepared by chemical vapor deposition (CVD). Major outgassing species from graphite substrate were H
2, H
2O, CO and CO
2. Various hydrocarbons such as C
xH
y (x=1-4) also desorbed at around 500 K. On the other hand, in the W-Re/C sample, the desorption amount of hydrocarbons was one order smaller than that of graphite substrate. However, a very large desorption of CO was observed at around 1200 K. For the W-Re/C material, the prebaking temperature required higher than 800°C.
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Ichiro TOYODA, Nobuaki GOTOH
1998 Volume 41 Issue 3 Pages
131-134
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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We studied on characteristics of the degassing of a titaniumdioxide-coated vacuum wall induced by the photon-assist-ed catalysis. The coating was performed on a 304 stainless steel wall using hydrolysis reaction of Ti [OCH (CH
3)
2]
4. A black lamp which emit only ultra violet light was employed as a photon source. During the irradiation desorption of water and hydrogen molecules is enhanced. The outgassing rate is reduced to the order of 10
-7 Pa m
3m
-2s
-1.
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Nobuaki GOTOH, Ichiro TOYODA
1998 Volume 41 Issue 3 Pages
135-138
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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We studied on characteristics of the photon-stimulated desorption of water from a chamber wall and on its application to a quick pump-down of a vacuum system. Employing a mercury vapor lamp as a photon source, we measured the amount desorbing gas molecules (mainly H
2O, H
2, CO, and CO
2) with a quadrupole mass analyzer in a titanium chamber and in a 304 stainless steel chamber for comparison. The orifice method allows the evaluation of the outgassing rate. After 1 hour of irradiation its value was reduced to the order of 10
-7 Pa m
3m
-2s
-1, irrespective of the wall materials.
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Azusa SIMAMURA, Nobuo TSUMAKI, Hiroyuki KITSUNAI, Tadashi OTAKA
1998 Volume 41 Issue 3 Pages
139-142
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Electrostatic wafer chucks are frequently used for wafer-handling in the vacuum systems of semiconductor manufacturing equipment, but the particles that they generate and that adhere to the back side of the wafer have recently become a serious problem. Chucks having a small area of contact with the wafer are usually effective in reducing the particle adhesion, but the chucking force is also smaller. The experiments described here evaluated the performance of an electrostatic wafer chuck that has a small area of contact with the wafer and that has a gap small enough to maintain the electrostatic chucking force. Particle adhesion was reduced by the smaller area of contact but was also strongly dependent on the polarity of the voltage applied to the chuck.
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Makoto TANAKA, Toshio URANO, Toru KANAJI
1998 Volume 41 Issue 3 Pages
143-146
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The cascade static lens gauge (CSL gauge) has been developed for the measurements of the total pressure in extremely high vacuum range. A simulation software “SIMION 3D” was used for the calculation of electric potential contours and of ion trajectories in the gauge. Then it was found that the gauge sensitivity can be increased when the “true ion” collection yield is enhanced by readjustment of the electrode-potentials. And found also that the effect of ESD ions can be considerably reduced by careful change of the geometries of several electrodes.
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Masamichi MATSUURA, Tadashi YAMAMOTO, Tadashi MORITA, Toshiharu KURAUC ...
1998 Volume 41 Issue 3 Pages
147-150
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The energy distribution of ions during magnetron sputtering enhanced with an inductively coupled rf plasma at 10
-110
-2 Pa was measured using a quadrupole mass spectrometer combined with an ion energy filter. The cathode in this sputtering system has an rf coil attached to the planar magnetron sputtering target. Other discharge properties of this plasma, including V-I characteristics and floating substrate potential, were also evaluated. The ion current of both the sputtered metal and the Ar gas increased significantly with increasing rf coil input power at a constant DC inut power to the target. Simultaneously, the energies of both ion species increased moderately. It was possible to increase the ratio of the ion current of the sputtered metal to that of the Ar gas by adjusting the rf coil input power in relation to the DC power. It was concluded that this sputtering method was very effective in ionizing sputtered particles in comparison with conventional magnetron sputtering.
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Tadashi MORITA, Tadashi YAMAMOTO, Toshiharu KURAUCHI, Masamichi MATSUU ...
1998 Volume 41 Issue 3 Pages
151-154
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Very thin Al
2O
3 film is required for insulation gap layers in future magnetic recording storage devices. In this study, very thin Al
2O
3 films of various thicknesses were prepared by means of a newly developed magnetron sputtering system based on a process that we have termed “magnetron sputtering enhanced with an inductively coupled rf plasma.” The cathode in this system has an rf coil attached to the planer magnetron sputtering target. The breakdown voltages of the Al
2O
3 films were about 5 MV/cm and leakage currents were ≤ 10
-7 A/mm
2. The surface roughness of the film was controllable by varying the input power to the rf coil, which also affected its breakdown properties. The Rmax for several of the film surfaces was ≤ 1 nm.
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Noboru KASHIWAGI, Toshiki KOBAYASHI, Masaru KITAGAWA, Eiji KUSANO, Hid ...
1998 Volume 41 Issue 3 Pages
155-158
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The energy distribution of positive ions in dc and rf magnetron sputtering enhanced additional rf plasma using Ti cathode was measured by an energy-resolved mass spectrometer. The rf-coil in front of the cathode generates an inductively coupled rf plasma enhancing the ionization of sputtered particles and discharge gasses in the region between the substrate and the cathode. The rf-coil power was changed from 0 to 200 W to investigate the effect of rf-power to energy distribution of sputtered particles. The Ti thin films produced by the sputtering were analyzed by X-ray diffraction.
The experimental results show that the enhanced energy of sputtered Ti particles ranged by the rf plasma from a few eV to about 90 eV in dc sputtering and from a few ten eV to about 110 eV in rf sputtering. The energy distribution of Ar positive ions shows similar tendency. The crystal orientation of deposited Ti thin films was affected by energy distribution of positive ions.
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Nobuyuki TERAYAMA, Hiroshi ASAMI
1998 Volume 41 Issue 3 Pages
159-163
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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With the purpose to produce a hard alumina film on a tool at low temperature, investigations were carried out to improve the arc discharge type high vacuum ion plating (ADIP) system.
As the result of the investigation, following three items can be listed as its main improvement.
(1) To provide a heating mechanism to the ionization electrode.
(2) To apply a negative bias to the cathode filament.
(3) To apply an asymmetrical dc pulse to the substrate in the frequency of 100 kHz.
By this, it was possible to ionize stably alumina vapour and to get a discharge current of 20 A at maximum.
A transparent film was obtained at the deposition rate from 80 to 100 nm/min.
The film structure was decided as amorphous by X-ray diffraction.
The film hardness showed 3600 HK at maximum and increased with the increase of pulse bias voltage.
The surface roughness was also determined as 2.2 nm (rms) from the observation with the atomic force microscope (AFM).
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Hironori KUMAZAKI, Seiki INABA, Kazuhiro HANE
1998 Volume 41 Issue 3 Pages
164-166
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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We propose a thin glass vibrator which is installed with micro-ball lens in PC connector as a photothermal vibrating type sensor. The vibrator was fabricated from a cover glass with accuracy of about 50 μm by ultrasound. In deposition process using an ion sputtering apparatus, continuous measurements of the resonance frequencies were possible without adjustments of an optical system. Resonance frequencies of the vibrator with 5 mm in length and 2 mm in width decreased from 3.280 kHz to 3.243 kHz during deposition thickness increase of 500 nm of Au. Possibility of practical use of a low price optical sensor was shown for measurement of depositon thickness.
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Kiyotaka WASA, Yoko HANEDA, Hideaki ADACHI
1998 Volume 41 Issue 3 Pages
167-170
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Epitaxially grown single crystal thin films of perovskite (Pb, La)(Zr, Ti) O
3, PLZT, families are important not only for the application for the electronic devices but also for the understanding of their physical and/or chemical properties. However, the epitaxial single crystal films include microstructures, although the electron diffraction and/or X-ray diffraction analyses suggest that these perovskite thin films comprise single crystal structure with 3-dimensional epitaxy. The growth of the microstructures is essentially governed by the initial stage of film growth. The microsstructures are controlled by the use of miscut substrates. It is demonstrated that epitaxial perovskite (001) PbTiO
3(PT) thin films on well-oriented (001)SrTiO
3 (ST) include microstructures resulting from island growth and/or nonuniform crystal growth. The epitaxial (001)PT thin films on miscut (001)ST substrate (miscut angle, 1.7 degree) show a single domain/continuous single crystal structure due to layer growth and/or step-flow growth. It is noted that the miscut substrates are essential for the structural control of perovskite thin films.
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Nobuo SAITO, Isamu NAKAAKI, Tomuo YAMAGUCHI, Shoji YOSHIOKA, Sigeaki N ...
1998 Volume 41 Issue 3 Pages
171-174
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Ge doped amorphous Si
xC
y : H films have been deposited by reactive rf magnetron co-sputtering of Si-Ge composite target in argon-methane gas mixture.
The effect of methane partial pressure P on the structural, optical and electrical properties of the films was investigated. With increasing P, the carbon content, the optical bandgap and the activation energy of conductivity increase. Both the B-value deduced from the Tauc's optical plot and the photoconductivity decrease rapidly at high P in the undoped a-Si
xC
y : H. The temperature dependence of conductivity shows the activated type conduction at high P, whereas the hopping conduction is predominant at low P. It is found that the addition of Ge could improve the reduction of the photoconductivity as well as the B-value at high P.
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Tetsuji KIYOTA, Masayuki TAKAHASHI, Yoshiro KUSUMOTO
1998 Volume 41 Issue 3 Pages
175-179
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Ti, W, Ta and their nitride films grown by sputtering were evaluated as the under layer of the sputtered Cu film with reflow process. The well nitrided films had good endurance against Cu-Si reaction at the annealing temperature higher than 680°C. The reflow characteristics of Cu film depend on a trench configuration and the Cu film thickness as well as the under layer species. Regardless of the reflow conditions, Cu on WNx revealed good reflow characteristics compared with Cu on TiNx or TaNx. This result shows that WNx is appropriate for the under layer material of reflow Cu. It was also found that the Cu reflow characteristics are highly correlated with the crystallinity of Cu film. The Cu film with (200) preferred orientation showed better reflow characteristics than that with (111) preferred orientation. However, in our experiments, there was no correlation between the reflow characteristics and the wettability of Cu on each under layer material.
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Yumi GOTOH, Satoshi KAWAMOTO, Shin FUKUDA, Makoto NAKAURA, Kazufuyu SU ...
1998 Volume 41 Issue 3 Pages
180-182
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Degradation behavior of silver thin film prepared on transparent polymer substrate of PET (polyethylene terephthalate) was investigated. Silver thin film was deposited on PET by DC magnetron sputtering at room temperature. When visible light irradiation with intensity of up to 5 SUN and a spectrum of AM (Air Mass) 1.5 was carried out through the PET at elevated temperatures, the reflected light became reddish purple-colored and the light reflectance decreased due to the formation of silver particles with a diameter of a few μm at the interface of silver and PET. The degradation was accelerated with both light intensity and temperature. The degradation kinetics with respect to the light reflectance was analyzed with a stretched-exponential function. The apparent activation energy of the degradation was estimated as about 50 kJ/mol.
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Taro NINOMIYA, Toshiaki MONNAKA, Narumi INOUE, Shigeru KASHIWABARA
1998 Volume 41 Issue 3 Pages
183-185
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Crystalline characteristics of Ta
2O
5 thin films prepared by off-axis pulsed laser deposition method (PLD) using an aperture plate were investigated. The film thickness at the center of substrate was the largest. The results of x-ray diffraction measurement showed that the crystalline quality at the film edge close to the target was better than that far from the target. These results are very useful for depositing the oxide thin films by the off-axis PLD method using an aperture.
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Akiyoshi NAGATA, Noritaka MOCHIZUKI, Tomoaki TATSU, Hideo OKAYAMA, Hir ...
1998 Volume 41 Issue 3 Pages
186-189
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Akiyoshi NAGATA, Takanobu MIMURA, Kouhei OKADA, Hideo OKAYAMA, Hiromu ...
1998 Volume 41 Issue 3 Pages
190-193
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Thin films of yttria stabilized zirconia (YSZ) for solid oxide fuel cells (SOFCs) were grown on porous Ni substrates by RF magnetron sputtering under the prepared conditions of reduced pressures form 0.4 to 0.9 Pa and substrate temperatures from room temperature to 500°C. Sputtered films were found to be the fully stabilized zirconia ones having cubic structures at those prepared conditions. A SOFC having YSZ films indicated a stable power generation property during 15 hours with 0.45 V although its value was reduced to lower half than the theoretical OCV of 0.915 V.
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Yasuhiro YAMAUCHI, Naoki SATO, Eiji HOSOKAWA, Satoru KISHIDA, Heizo TO ...
1998 Volume 41 Issue 3 Pages
194-197
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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We prepared BaRbBiO (BRBO) superconducting ceramics by a self flux method, and carried out the X-ray photoelectron spectroscopy (XPS) measurements for the surfaces of the as-prepared and polished BRBO specimens. From the results, we found that impurities on the surfaces of the BRBO specimens were removed by polishing them mechanically in air, and that the specimens contained the constituent elements of Ba, Rb, Bi and O. In addition, the surface compositions of BRBO specimens seem to be dependent on the composition of Bi starting materials.
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Akito TANAKA, Yasuhiro YAMAUCHI, Satoru KISHIDA, Eiji HOSOKAWA, Taizo ...
1998 Volume 41 Issue 3 Pages
198-201
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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We heated the Bi
2Sr
2Ca
n-1Cu
nO
y (BSCCO) single crystals in air and investigated their surfaces with X-ray photoelectron spectroscopy (XPS). From the results, we found that the clean surface, where carbon and oxygen impurities were not included, was obtained by heating the BSCCO single crystal at 400-500°C in air for 1 h. In addition, any deterioration of the BSCCO single crystal surface does not occur by the heat-treatments in the chemical composition and state of the surface.
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Naoki TAKAHASHI, Osamu TSUKAKOSHI, Toshio HAYASHI
1998 Volume 41 Issue 3 Pages
202-205
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Recently, highly sensitive helium leak detectors with a lower detection limit of under 10
-12 Pam
3/s have been required in fields which use highly airtight systems. To satisfy this requirement, a typical solution has been to use a secondary electron multiplier as an ion collector or to use a double turbo molecular pump system. But these systems have the problems of unstable sensitivity and higher system costs. To avoid these problems, we developed a highly sensitive magnetic deflection type mass spectrometer by optimizing the ion optics.
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Kazuhiko SUZUKI, Yuichi TERATANI, Toshio URANO, Shozo HONGO
1998 Volume 41 Issue 3 Pages
206-209
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Computer simulation of electron trajectories in a Cascade Static Lens Gauge (CSLG) has been carried out in consideration of space charge effect. The space charge distribution was estimated by the accumulation of residence time of electrons in each mesh. It was confirmed that electron trajectories were spread by a proper amount of space charge, but trajectories have not been spread so to bump into anode electrodes. This is caused by the impossibility of electron emission from the filament due to the intense space charge around it. It is considered that this will be solved by the increase of initial velocity of emitted electrons.
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Yuichi ISHIKAWA, Toshihiko YOSHIMURA
1998 Volume 41 Issue 3 Pages
210-212
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Hydrogen is a major residual gas constituent in extremely high vacuum (XHV) and its outgassing behavior has been suggested to be closely related to its concentration and distribution in the surface layers of materials used to fabricate vacuum chambers. This paper presents a preliminary results of a series of study taken to measure the hydrogen concentration in the surface layer as well as its distribution by a three-dimensional atom probe, thus leading to a better under-standing of the outgassing process in XHV. Deuterium gas was adsorbed in a nickel base superalloy single crystal atom probe specimen having γ'/γ interface in the apex region at 773 K in a range of pressure 0.0130.04 Pa for 300600 seconds. Then, atom by atom determination of deuterium distribution and concentration in the surface was performed. The atom probe analysis shows that deuterium is adsorbed only in the outermost surface and no trapping occurs at the γ'/γ interface.
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Miyuki YAMANE, Nobuo TSUMAKI, Shigemi HIRASAWA, TAKAO EBINE
1998 Volume 41 Issue 3 Pages
213-216
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The outgassing characteristics of Invar samples oxidized in atmosphere at 600°C was measured by thermal desorption spectroscopy (TDS). The Outgassing rate of the oxidized Invar samples was three times larger than that of as-received Invar samples. After outgassing by heating in vacuum, no significant difference was found in the adsorption rates in atmosphere between the oxidized and as-received Invar samples. Once the samples were heated in vacuum, the length of exposure in atmosphere had little influence on the adsorption rates.
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Tomio KUBO, Yoshihiro SATOH, Yoshio SAITO
1998 Volume 41 Issue 3 Pages
217-221
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Some kinds of the electrical cables and elastomer/plastomer materials, though having high outgassing rates, are occasionally used in a high vacuum system. In order to evaluate the ultimate pressure of the system in which those materials are to be installed, their outgassing rates have been measured as a function of pumping time by a through-put method. The outgassing rates of the cables and glass-fiber sleevings ranged from 10
-9 to 10
-5 Pa·m
3. s
-1. m
-1 at 100 h, depending on the insulation materials or varnishing treatment. From the tests of the elastomer/plastomer materials, it was ascertained that the organic materials give high outgassing rates of the orders of 10
-5 to 10
-3 Pa·m
3·s
-1·m
-2 at 100 h.
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Verification of Theory by Experiments
Shin KAMADA, Tadashi SAWADA, Wataru SUGIYAMA, Jun-ichi TAKEMOTO, Shuji ...
1998 Volume 41 Issue 3 Pages
222-226
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The authors proposed a theory in regard to the pumping performance of a dry scroll vacuum pump. The authors analyzed its validity by experiments using air. In this study, the ultimate pressure and pressure in gas pockets were measured using air, argon and helium. A comparison of the measurements with theoretical predictions has shown a reasonable agreement for air and argon, but has shown some discrepancy for helium.
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Akinobu IWAI, Shinichi KOBAYASHI, Yoshio SAITO
1998 Volume 41 Issue 3 Pages
227-230
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Influence of Cu electrode surface conditions, such as chemical composition and crystal structure of surface, on electrical breakdown in vacuum has been investigated. The chemical compositions were analyzed by a X-ray photoelectron spectroscopy (XPS) and the crystal structure was quantified by measuring residual stresses. The XPS analysis revealed that electrode surfaces were completely cleaned by repetitive breakdowns. The values of the residual stress varied significantly after 500 breakdowns. From breakdown current voltage waveforms, it was demonstrated that breakdown mechanism might be altered by repetitive breakdowns. The mechanism of breakdowns has been discussed on the basis of field electron emission caused by not only metallic but non metallic mechanism.
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Shinichiro MICHIZONO, Yoshio SAITO, Takayuki SATO, Shinichi KOBAYASHI
1998 Volume 41 Issue 3 Pages
231-234
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Klystrons used in an accelerator have alumina rf windows installed in their output portion in order to isolate vacuum from atmosphere and pass rf power. Window breakdown probably related to the surface charging is one of the difficulties to develop klystrons. The surface potentials of as-received alumina samples are measured. Secondary electron emission coefficients (δ) on the charged area (more than + 40V) are less than 0.2, which results from secondary-electron trapping on the charged surface. High power tests using a resonant ring are examined. Positive charging is considered to be due to multipactoring (a resonant multiplication (in rf fields) of secondary electrons) and surface flashover. After the high power tests, electrons are irradiated in order to modify the surface charging. The effects of the irradiation are also studied by measurements of surface potentials.
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Tatsuya SUGIMOTO, Shinichiro MICHIZONO, Yoshio SAITO, Shinichi KOBAYAS ...
1998 Volume 41 Issue 3 Pages
235-238
Published: March 20, 1998
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It has been believed that the crystal structure of alumina influences the surface flashover voltage. Residual stress is one of numerical indicators reflecting crystal structure of the material. In this experiment, residual stresses before flashover, after one flashover and after 200 flashovers were measured. For a non annealed alumina, measured values of residual stresses were -90.8 MPa (compressive stress, before flashover), -75.1 MPa (after one flashover), and 108 MPa (tensile stress, after 200 flashovers). For an annealed (1400°C in air, 4 hours) alumina, these were 52.4 MPa (tensile stress, before flashover), 16.5 MPa (after one flashover), and 10.4 MPa (after 200 flashovers).
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Naomu KITANO, Namio MATUDA, Takeshi AZAMI, Hironori MATUURA
1998 Volume 41 Issue 3 Pages
239-241
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Secondary electron emission coefficients δ and work function φ of electron irradiated Cu surfaces were measured as a functionof electron charge amounts,
q mC.
It was found that φ increased from 4.25 eV (
q = 0 mC) to 4.51 eV (
q =10 mC) while maximum of δ decreased from 1.5 to 1.2. The result of φ at
q = 10 mC was coincident with table value of φ
carbon = 4.6 eV.
Therefore, it is concluded that increasing work function of Cu surfaces by carbon contamination prevents the secondary electron emission from surface, consequently leads to the reduction of δ.
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Akihiro FUJII, Hisasi YAMAZAKI
1998 Volume 41 Issue 3 Pages
242-245
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The process of cleaning of a tantalum (100) surface was investigated by low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and high resolution electron energy loss spectroscopy (HREELS). The sample used was heated at 1700 K for 120 h in UHV and oxygen atmosphere to remove carbon impurity and showed a 3 × 3 LEED pattern and no carbon signal in AES. This means that oxygen was incorporated in the crystal lattice forming an ordered structure. In order to get a clean surface the oxygen had to be removed. For this purpose the crystal was flashed repeatedly up to 2780 K. At some stages of flashing LEED observation and AES measurement were done. The LEED patterns showed 8 × 8, 2 × 1, 3 × 1 and 4 × 1 superstructure. Finally by repeated flashing at 2780 K for 10 s, the crystal showed a 1 × 1 LEED pattern. No impurity signal was observed in AES, and no vibrational excitation signals in HREELS. From these facts, we conclude that a tantalum (100) surface became clean.
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Calibration of the Sensitivity of Mass Spectrometer
Kyoko TAKEUCHI, Tomonari TANAKA, Yutaka TUZI
1998 Volume 41 Issue 3 Pages
246-250
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The temperature-programmed desorption spectra (TPDS) of water molecules on solid surfaces can be accurately obtained by the direct measurement of the flux density of molecules desorbed from the surfaces. For this purpose, the ion source of the quadrupole mass spectrometer (QMS) was covered by Cu envelope with collimator cooled by liquid nitrogen, and the sample surface was placed just in front of the collimator. The change of the saturation vapor pressure with the phase transition of ice from amorphous to crystalline form was observed by this method. The calibration of the QMS ion current for the rate of desorption of water molecules has been made use of the saturation vapor pressure of crystalline ice.
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Hiroshi MURAKAMI, Kazuhiro ENDO, Sadafumi YOSHIDA, Yo ICHIKAWA, Kentar ...
1998 Volume 41 Issue 3 Pages
251-254
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Superconducting thin film is promising for use in Josephson-functioned electronic devices and magnetic sensors. Fabrication of the film using the CVD method under grounded conditions has the problem of nonuniform deposition caused by convection, while stable electronic performance and homogeneous morphology are required of the thin film. To mitigate convection, fabrication of the film by MOCVD under microgravity conditions planned. Y (DPM)
2, Ba (DPM)
2 and Cu (DPM)
2 are the metalorganic compounds and Ag
2O and AgO act as oxidizers when heated to temperatures above 300°C. The MgO substrate is heated to 700-850°C. All the metalorganic compounds are completely vaporized by adjusting their temperatures. Using a grounded electric furnace whose characteristics are made to simulate those of the JEM gradient heating furnace, generation of oxygen gas and fabrication of Yttrium thin film were attempted. Although superconducting performance has not been confirmed, we believe it will be achieved through more detailed investigation of the heating condition. Results of the preparation of the space experiment on JEM are described.
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Ayako HIOKI, Akio OKAMOTO, Kazuki NATSUKAWA, Soichi OGAWA
1998 Volume 41 Issue 3 Pages
255-257
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Various ultra-thin Pt films (UPF) have been made by low energy sputtering and studied as a function of the sputtering time. Their resistance was measured at various temperature. It is found that two main different average thickness of the Pt films have different two-dimensional fine structures. One of these specimens discloses a discontinuous island structure whereas the other does a semicontinuous one. The electrical properties of these UPF were measured in both vacuum atmosphere and hydrogen. It is found that the electrical conductivity of the UPF in hydrogen gas was higher than in vacuum. Such difference depends on the two-dimensional fine structure characteristics. Moreover, It is shown that there is reproducibility in the gas response.
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Tsunehisa TANAKA, Koji INOUE, Yoshihiko SUZUKI
1998 Volume 41 Issue 3 Pages
258-261
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The resistance for anisotropic etching of thin film is important for the process of micromachining technology. Therefore, various thin films such as Cu, Ta, Ni, Mo, Pt, W, Ti, Zr, Nb, Au, Cr and TiN have been deposited on Si wafer, and have been tested to investigate whether they are etched or not by three kinds of anisotropic etching solutions; TMAH, EDP and KOH. Results indicate that Cr, Mo, Nb, Zr, TiN/Ti, Ni/Cr, Pt/Cr and Au/Cr thin films are not etched by TMAH solution. Similarly, Ti, TiN, TiN/Ti, Cr, Ta, Nb, Zr, Pt/Ti, Pt/Cr, Au/Ti and Au/Cr thin filmsare not etched by EDP solution. Moreover, Zr and Pt/Ti thin films are not etched by KOH solution. Since KOH solution is more reactive than TMAH and EDP solutions, Cr film has resistance for both TMAH and EDP solutions. However Cr film was peeledoff from the substrate in KOH solution.
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Toshinobu NAKAJIMA, Yuji FUJISAWA, Masatoshi TANAKA, Seiji USAMI
1998 Volume 41 Issue 3 Pages
262-265
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Temporally resolved absorption and emission spectra of the plume induced by laser ablation of NiO in oxygen gas were measured with several detection angles. Time-of-flight spectra of several species and their angular dependences are obtained. They are compared with the results of similar experiments in vacuum. In the case of ablation in oxygen gas, most probable velocity (υ
p) of Ni ions is lower, and υ
p of O neutrals is higher. Number densities of excited species are higher. υ
p and number densities are less dependent on the angle. These results are well explained by multiple collisions with ambient oxygen molecules.
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Akio SUZUKI, Hiroshi YAMANISHI, Daisuke TANAKA, Takanori AOKI, Tatsuhi ...
1998 Volume 41 Issue 3 Pages
266-269
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The 100200 nm-thick ZnO : M (M=Ga
2O
3, In
2O
3, Al
2O
3, Ag
2O, CuO and SnO
2) films in which droplet formation was suppressed have been deposited on glass substrates at room temperature by a pulsed laser deposition technique using SHG of Nd : YAG laser (λ= 532 nm). Transmittance in the as-deposited state of ZnO : Ga
2O
3 (2 wt%) film was the smallest among all the ZnO : M films : the film was colored with dark brown. When the films were annealed at 390°C for 50 min, the transmittance of the films increased markedly. The difference in the transmittance between the as-deposited state and the annealed state
ΔT was 76% at the wavelength of 400 nm. It was found that maximal transmittance difference
ΔT
max was 91% at the wavelength of 472 nm. From XRD spectra, the coloring phenomenon was explained from the fact that the Zn (100) and Zn (101) peaks were present in the as-deposited state and absent in the annealed state, and ZnO peaks such as (200), (101) and (100) were present in the annealed state and absent in the as-deposited state. It is thought that the ZnO doped with Ga
2O
3 films are useful as a high density optical memory due to the short wavelength (400 nm) of the next generation.
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Akio SUZUKI, Hideki FUJIWARA, Tomoya FUKUDA, Takanori AOKI, Tatsuhiko ...
1998 Volume 41 Issue 3 Pages
270-273
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Thin films of ZnO : Ga (GZO) have been deposited on glass substrates by a pulsed laser deposition technique using SHG of Nd : YAG laser (λ = 532 nm). The size of droplets was lessened by a reduction of the thermal ablation effect in the evaporation processes. Therefore, electrical and optical properties were improved : (1) when prepared at a laser output of 0.2 W, the lowest resistivity of 2.77 × 10
-4 Ω·cm and an optical transmittance of more than 95% in the visible region of the spectrum were obtained for 100-150 nm thick GZO (4 wt%) films deposited at substrate temperature of 300°C and on oxygen flow rate of 2 sccm, (2) when prepared at a laser output of 1 W, the lowest resistivity of 6.90 × 10
-4 Ω·cm and an optical transmittance of more than 85% and a haze ratio of 33% (λ =550 nm) were obtained at substrate temperature of 200°C and on oxygen flow rate of 2 sccm. Thus, the texture structures with the confinement effect of incident light were observed for 400-500 nm thick GZO (4 wt%) films because the concavo-convex surfaces due to droplets generated from start of deposition.
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Rieko YAGUCHI, Shizuka SAKUMA, Eiji KAMIJO
1998 Volume 41 Issue 3 Pages
274-277
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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Transparent and conductive films of SnO
2 doped ZnO are prepared by electron cyclotron resonance (ECR) sputtering using ZnO- (1 to 30) mol%SnO
2 sintered cylindrical targets in an Ar atmosphere at various substrate temperatures on glass substrate (Corning 7059). The thin films prepared by sputtering wit a ZnO target containing 3 mol%SnO
2 show low resistivity and crystal structures of hexagonal ZnO. The electrical resistivity of as sputterd SnO
2 doped ZnO films when substrate temperature is 473 K and gas pressure is 2.7 × 10
-1 Pa is 6.43 × 10
-3 Ωm and decreases down to 1.51 × 10
-4 Ωm by a vacuum annealing at 873 K. This film show optical transmission higher than 80% at an wavelength of 600 nm.
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Fumiharu YAMAZAKI, Shin FUKUDA, Masato KOYAMA, Makoto NAKAURA, Kazufuy ...
1998 Volume 41 Issue 3 Pages
278-280
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The electronic properties of ITO (Indium Tin oxide) films prepared on PET (polyethylene terephtalate) substrates were investigated. ITO films were deposited with DC magnetron sputtering method using In-Sn alloy target under the condition that the minimum resistivity could be obtained with Ar and O
2 gas mixture. Organic compounds such as acetaldehyde and ethylene glycol were found to be released from PET upon heating. SIMS measurements revealed that the amount of gas released from the PET substrate is parallel to that of residual carbon in ITO films deposited on the PET substrate. This result implies the desorbed gases were incorporated into the ITO film during the deposition. When ITO film with larger carbon content was heated at 130°C for 5 hours, the carbon concentration was decreased to 1/10 of initial. Hall measurements showed that the increase in resistivity after heat treatment was due to the decrease in the carrier density.
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Shigeharu TAMURA, Hiroyuki MAGARA, Tadashi ISHIDA, Shoichi MOCHIZUKI, ...
1998 Volume 41 Issue 3 Pages
281-284
Published: March 20, 1998
Released on J-STAGE: October 20, 2009
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The tin oxide (SnO
2) films are thermally and chemically stable, and have been applied to various fields. The SnO
2 (non-doped) films were prepared by a photochemical vapour deposition (photo-CVD) process. TMT (Sn (CH
3)
4) and O
2 (containing 4 mol.% O
3) were used as the source materials, and a low-pressure mercury lamp was used as the light source. By the combination of a linearly focused low-pressure mercury lamp through a semi-cylindrical suprasil window and a reciprocation of the substrate, a good uniformity along the 8 cm ×10 cm area was realised at a substrate temperature of 200 and 250°C. The SnOO
2 films prepared at lower temperature had better uniformity. The minimum resistivity of 6.8 × 10
-3Ω·cm was obtained at a substrate temperature of 250°C.
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Takeshi YOSHIZAWA, Takeshi TANAKA, Keishi KAWABATA
1998 Volume 41 Issue 3 Pages
285-288
Published: March 20, 1998
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The Schottky barrier diodes of sputtered TiN
x on n-type silicon have been prepared by an RF-DC coupled magnetron sputtering system which employs a low RF power and DC bias. The electrical properties of TiN
x/Si system prepared by this method have been investigated. It was found that the TiN
x/Si system prepared at the target DC bias voltage of-100 V have the Schottky barrier with low sputtering damage where the Schottky barrier height is 0.56 eV. It was suggested that the RF-DC coupled magnetron sputtering is useful for preparation of the Schottky barrier diode.
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