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Hitoshi AKIMICHI, Naoki TAKAHASHI, Toshio HAYASHI, Yutaka TUZI
2000 Volume 43 Issue 3 Pages
177-180
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The characteristics of a newly developed axial-symmetric transmission gauge (AT gauge) for the measurement of wide pressure range were examined. The secondary electron multiplier used in the previous gauge was replaced by a Faraday cup for analog measurement of ion current. The lower limit of the pressure measurement at present was estimated to be about 10
-11 Pa. The sensitivity factor of the AT gauge in the pressure range from 10
-10 to 10
-6 Pa calibrated by conductance modulation method and in the pressure range from 10
-8 to 10
-2 Pa calibrated by direct comparison with reference gauges were (2.3±0.04) ×10
-3 Pa
-1 for hydrogen and (5.8±0.1) ×10
-3 Pa
-1 for argon, respectively. Uncertainty of the ion current of the AT gauge by the fluctuation of the voltage 1 V of the energy filter was estimated to be about 1%. Long term stability of the electron emission current, intensity of gas phase ion and background signal was estimated to be about 0.03, 0.2 and 6.5%, respectively.
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Shigeki MIZUSHIMA, Masaaki UEKI, Yoshiaki NEZU, Akira OOIWA
2000 Volume 43 Issue 3 Pages
181-183
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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A new electronic mass comparator, capable of automatic weighing in vacuum, was introduced into the National Research Laboratory of Metrology. The standard deviation of 0.1 μg, a factor of 3 smaller than the standard deviation of the best previous measurement using a mechanical balance, was achieved for the mass comparison between two 1-kg weights. For eight days, mass difference of two 1-kg weights with the surface area difference of 66.7 cm
2 was measured in vacuum. We observed an outgassing rate of 9×10-
6 Pa·
3·s
-1·m
-2 after an evacuation for 3.9-6.8 hours, and below 6×10
-9 Pa·m
3·s
-1·m
-2 after an evacuation for 107 hours. Residual gas in the vacuum chamber, which housed the electronic mass comparator, was analyzed to monitor the oil contamination. At a total pressure of 5.5×10
-4 Pa, we observed the main peaks due to hydrocarbon at 41, 43, and 57 amu with a partial pressure of 3×10
-6 Pa.
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Okio NISHIMURA, Kazuhiko TONOOKA
2000 Volume 43 Issue 3 Pages
184-187
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The magnetoresistive Co-Ag thin films were deposited on glass substrates in a magnetic field at room temperature by an rf magnetron sputtering system. The magnetoresistive properties of the as-deposited samples was investigated in relation to the intensity of the bias magnetic field applied parallel or perpendicular to the film surface during deposition. Samples deposited in a bias magnetic field showed larger responses in magnetoresistance than that of samples prepared by the conventional sputtering. The magnetoresistive response of the samples deposited in a bias magnetic field increased with increasing intensity of the magnetic field, whereas no saturation of the trend was observed in the range of 9 mT for parallel and 150 mT for perpendicular configurations.
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Konosuke INAGAWA, Naoki HIBINO, Toshihiro ZENIYA, Yoshifumi OTA, Isao ...
2000 Volume 43 Issue 3 Pages
188-192
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Transparent Al
2O
3 films with high gas barrier properties were deposited on a PET film substrate by a web coating method using an activated reactive evaporation (ARE). The web speed was 100 to 700 m/min. The thickness of the Al
2O
3 film was 5 to 30 nm. ARE was beneficial for two reasons. One was the enabling of sound Al
2O
3 formation, and the other was the smooth winding of the Al
2O
3 deposited PET film achieved by neutralizing the negative charges, i.e., secondary electrons resulting from electron beam radiation on the Al evaporation source. The Al
2O
3 coated PET film showed an excellent barrier performance of about 1 g/m
2 · day for water vapor transmission and about 1.5 cm
3/m
2 · day · atm for oxygen transmission, respectively, and an optical transmittance near to that of the uncoated PET. Results from analyses of Auger electron spectroscopy and X-ray diffraction, and observations of transmission electron microscopy and atomic force microscopy of the Al
2O
3 films are also described.
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Hideki YAMAMOTO, Noriaki SAIGA, Katsumi NISHIMORI
2000 Volume 43 Issue 3 Pages
193-196
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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We have reported formation of ZnO thin films deposited on z-cut LiNbO
3 substrates using RF-sputtering technique. The substrate temperatures during deposition were changed from 300 to 703 K in various oxygen-argon atmospheres. ZnO (002) peak intensity depending on gas flow rate of oxygen to argon, substrate temperature and anneal temperature were observed. The film showed the crystalline growth highly oriented at [002] direction, when the film on z-cut LiNbO
3 substrate was deposited at 603 K in Ar (80%) +O
2 (20%) gas or annealed at 890 K in argon atmosphere.
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Tadashi NAKAMURA, Kunio OKIMURA
2000 Volume 43 Issue 3 Pages
197-200
Published: March 20, 2000
Released on J-STAGE: January 30, 2010
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Ti atom density distributions on the radial direction in Ti-O
2 rf (13.56 MHz) magnetron sputtering were investigated by an atomic absorption method. We also measured Ti atom densities in pure Ar discharge for the comparison with that in Ar-O
2 mixture discharge. At a total pressure of 2.7 Pa and rf power of 200 W, Ti atom density in Ar-O
2 discharge was nearly two order smaller than that of metallic mode. The maximum value of atom density for radial distance was obtained at the vicinity of the inside of the location with maximum transverse magnetic field strength (r= 30 mm) for all experimental conditions. Dependence of Ti atom density distributions on total pressure of Ar-O
2 gases and axial distance were demonstrated.
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Tetsuya NISHIGUCHI, Yoshiki MORIKAWA, Masaharu MIYAMOTO, Hidehiko NONA ...
2000 Volume 43 Issue 3 Pages
201-204
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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In order to obtain an active ozone beam and make full use of ozone oxidation ability, we used laser ablation method. High concentration ozone from an ozone jet generator was solidified on a sapphire substrate and then pulsed KrF laser was irradiated to the solid ozone. Ablated species and their velocity distribution have been investigated using time-of-flight method through a quadrupole mass filter.
Ablated species were mainly a mixture of ozone, molecular oxygen and atomic oxygen. As for their velocity distribution, ozone showed a thermal equilibrium, while molecular oxygen showed many slower components. Ablated ozone yields were strongly dependent on laser power and showed a maximal. The ratio of ozone against molecular oxygen in the mixture increased as the substrate temperature became higher, probably because of increase in the purity of the solid ozone on the substrate. Ozone velocity varied from 1500 K to 2500 K depending on the laser power and the substrate temperature, which means that we can supply an ozone beam that has controlled purity and velocity.
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Katsuto TANAHASHI, Michimasa KIKUCHI, Naohisa INOUE, Yusuke MIZOKAWA
2000 Volume 43 Issue 3 Pages
205-208
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Equilibrium concentration of point defects under various stages in growing silicon crystal is theoretically examined. Formulas of concentration of point defects corresponding to solid-liquid interface, early cooling stage and including secondary defects are proposed. It is suggested that equilibrium concentration is not unique and that previous consideration is not applied for actual crystal growth.
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Sonoko TSUKAHARA, Sakae INAYOSHI, Yoshirou OOTSUKA, Shunji MISAWA, Aki ...
2000 Volume 43 Issue 3 Pages
209-213
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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One of the practical and low cost treatments, an electrolytic polishing (EP) was applied to aluminum alloys for vacuum equipment use to optimize polishing condition utilizing the Taguchi Methods by small samples. EP samples prepared at the optimal conditions, i.e. high temperature of the polishing liquid and the first rinse water, had outgassing rate as low as chemical polishing (CP). Uniformly thinner and dense surface oxide barrier layer and thicker porous columnar oxide surface layer were the product of the optimal and the starting EP treatments, respectively, and they corresponded to lower and higher outgassing quantity, respectively. Pumping time dependence of outgassing rate
q of EP and CP treated chamber samples showed that the formers were higher than the latter, respectively. At ultimate pressure
q of EP and CP samples are 3×10
-12 Pa·m·s
-1 and 1×10
-12 Pa·m·s
-1, respectively.
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Yuichi ISHIKAWA
2000 Volume 43 Issue 3 Pages
214-218
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Outgassing rates from the walls of a fully baked vacuum chamber made of type 304 stainless steel (volume : 0.005 m
3, surface area : 0.4 m
2) were measured by two methods, the throughput method, where the outgassing rate is determined from the pressure drop (measured by two ionization gauges) across an orifice with a conductance of 0.0047 m
3/s for nitrogen during evacuation and the pressure rise method, where the chamber is sealed off at 10
-8 Pa and the rise in pressure with time is measured by a spinning rotor gauge. In both measurements the major outgassing species is hydrogen. The pressure rise is linear for as long as 115 h with the pressure increasing by a factor as large as 10
6 indicating a constant outgassing rate and zero sticking probability of the desorbed hydrogen on the stainless surface. The outgassing rates measured by the two methods in several sequences of air exposure and baking agree well with each other and lie in the range of 4-5×10
-10 Pam/s, which is a typical value for fully baked stainless steel UHV chambers. A quadrupole mass spectrometer shows some pumping action against desorbed gas species, particularly hydrogen, while outgassing methane and carbon monoxide. A nude Bayard-Alpert gauge pumps methane but produces carbon monoxide.
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Ken-ichi KANAZAWA, Shigeki KATO, Yusuke SUETSUGU, Hiromi HISAMATSU, Ma ...
2000 Volume 43 Issue 3 Pages
219-222
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The commissioning of KEKB accelerator (KEKB-factory) started in December, 1998. The vacuum system is working almost satisfactorily although several troubles occurred near the interaction region. The photon stimulated gas desorption coefficient of copper beam chamber is decreasing steadily and reached to around 1×10
-5 molecules photon
-1 at the integrated linear photon flux of 1×10
24 photons m
-1. The beam lifetime is increasing with the integrated beam current but is shorter than that expected by the average pressure especially for the Low Energy Ring. A pressure burst was observed at a straight section of the positron ring. The Helicoflex vacuum sealing is stable. Bellows and gate valves with RF-shield structure showed no excess heating up to the storage current of 500 mA.
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Takezo OHUCHI, Yuko HIROHATA, Tomoaki HINO, Noriyuki INOUE, Akio SAGAR ...
2000 Volume 43 Issue 3 Pages
223-226
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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For Large Helical Device, LHD, first cycle and second cycle experiments were conducted in 1998. Before each cycle experiments, SS316L samples were installed at the inner wall along poloidal direction. After the experiments, these samples were extracted, and the changes of surface morphology, atomic composition and gas desorption were investigated.
After the first cycle experiments, dominant erosion and deposition of wall materials were observed, and the oxygen impurity level at the surface was considerably large. After the second cycle experiments, erosion and deposition almost disappeared, and the thickness of oxide layer largely decreased. In addition, the amount of desorbed impurity gas was reduced, compared with the case of first cycle experiments. In the second cycle experiments, it was seen that the plasma stored energy largely increased due to the reduction of the radiation power. The impurity level at the inner wall was largely reduced by the second cycle experiments.
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Shinichiro MICHIZONO, Yoshio SAITO
2000 Volume 43 Issue 3 Pages
227-230
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Alumina rf windows are used at the output portion of the klystrons (2856 MHz, 50 MW in maximum, 4 μs, 50 pps) in KEKB linac. Breakdown of the windows is one of the most serious problems as klystron failures. The breakdown is caused by 1) multipactor, and 2) surface discharges. The multipactor is the resonant multiplications of the secondary electrons in the rf fields and the surface discharges are probably due to the release of the electrons accumulated on the surface. In both cases, the alumina surfaces are considered to be charged. In this report, the surface potentials are evaluated by two ways. One way is to measure the surface potentials with the window structure. The measured potentials are the potentials by which incident electrons are affected. Another way is to measure the potentials with the reverse side connected to the earth. The measured potentials correspond to the surface charge density. The surface potentials at multipactor region (3 MW) and surface discharge region (220 MW) are measured. The higher surface potentials at higher transmission power are obtained. The accumulated charges are considered to be determined by the field-emitted current mainly emitted at the edges of the ceramics. The threshold of the rf breakdown is considered to be improved by thicker TiN coating around the periphery of the ceramics, which reduces the primary electrons.
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Naoki TAKAHASHI, Hitoshi AKIMICHI, Toshio HAYASHI, Yutaka TUZI
2000 Volume 43 Issue 3 Pages
231-234
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The discrimination between the non-dissociative molecular ions and the fragment ions is one of the important factors for the quantitative measurements of partial pressures by a quadrupole mass spectrometer (QMS). The measurements of H
2, CH
4, and O
2 by QMS with the Bessel-Box type energy analyzer show that the energy spectrum of the molecular ion and of the fragment ion at the same mass to charge ratio are very different each other. The difference can be applied for the distinction between the molecular ions and the fragment ion.
Furthermore, the spectra of fragment ions depend on their parent molecular ions probably due to the different dissociation process of molecules by the electron bombardment.
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Yusuke SUETSUGU, Hiromi HISAMATSU, Ken-ichi KANAZAWA
2000 Volume 43 Issue 3 Pages
235-238
Published: March 20, 2000
Released on J-STAGE: January 30, 2010
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Some cold cathode gauges (CCGs) in KEKB Accelerator show different behavior from other ones. These gauges have following characteristics : (1) The locations of these CCGs are limitted to just downstream side of bending magnets where the synchrotorn radiation is intense. (2) The discharge current is proportional to the beam current. (3) The discharge current is observed even without a permanent magnet of CCG. (4) The discharge current per unit beam current approaches to a constant value as the integrated beam current increases. From these characteristics, the observed abnormal discharge current of these CCGs is considered to be due to the photoelectrons generated by the synchrotron radiation. A simulation shows that the electrons are not generated inside of the beam chamber but inside the gauge chamber by reflected SR or accelerated photoelectrons that are produced inside the beam chamber. Attaching small dipole magnet at the neck of CCG port can remove the effect of secondary electrons.
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Shigemi SUGINUMA, Masahiro HIRATA
2000 Volume 43 Issue 3 Pages
239-242
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Secondary standard ionization vacuum gauge VS-1 is a triode gauge. Simulation of the electrical potential profile of the gauge, electron trajectory emitted from a hot filament, and ion current produced by ionization of gas by the electron assuming a simple electrode geometry was done. The increase in sensitivity coefficient depending on grid potential and the decrease in that depending on filament potential agreed with experimental results by 5%. The increase in sensitivity coefficient depending on filament displacement and ion collector tilting from its regular position was also explained by simulation.
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Y. S. KIM, Masahiro TOSA, Akira KASAHARA, Kazuhiro YOSHIHARA
2000 Volume 43 Issue 3 Pages
243-246
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The synthesis of uniform hexagonal boron nitride layer was enhanced by surface segregation method using a r. f. magnetron sputtering system utilizing a helicon wave nitrogen plasma and in-situ annealing in an ultrahigh vacuum. Scanning Auger spectroscopy and X-ray photoelectron spectroscopy analyses showed that the deposited film surface was almost covered with the h-BN layer segregated after the annealing at 800 K. The surface of h-BN layer was found to have the attractive force less than 1 nN and the good insulating property up to 3 V. These surface properties can be applied to fabricate nano scale structure and electric micro devices as an advanced substrate.
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Akira KUROKAWA, Shingo ICHIMURA, Ken NAKAMURA, Hiroshi ITOH
2000 Volume 43 Issue 3 Pages
247-250
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The sample contamination in a loadlock chamber, caused by particle sticking, adsorption of gas and moisture in a loadlock chamber and back stream from pumping systems, was investigated. In order to eliminate the first two sources of contamination, a clean silicon sample was prepared in a glove box filled with particle-free nitrogen gas, and the sample was transferred to the loadlock chamber without exposing to air. To observe the contamination during pumping, the last source of contamination, a clean sample was set in the loadlock chamber and after evacuation surface contaminant was evaluated by C1s intensity of XPS spectra. Several evacuation procedures were compared and we concluded that oil-free pumping system is essentially important for contaminant-free introduction of a clean sample.
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Yasuhito GOTOH, Yu KASHIWAGI, Masayoshi NAGAO, Hiroshi TSUJI, Junzo IS ...
2000 Volume 43 Issue 3 Pages
251-254
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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A gated niobium nitride field emitter array was fabricated by transfer mold method and etch back method, in order to show the feasibility of niobium nitride thin film as a cathode material of vacuum microelectronics devices. Silicon substrate was etched to have pyramidal mold and its surface was oxidized. Niobium nitride thin film was deposited onto the oxidized mold by ion beam assisted deposition. After the deposition, sample was bonded to glass plate and the silicon mold was removed by mechanical and chemical etching. After etching, molybdenum gate was deposited and the gate aperture was fabricated by etch back process. The electron emission property was measured in high vacuum and field emission was confirmed.
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Masaaki YASUDA, Takeshi UNE, Hiroaki KAWATA, Kenji MURATA
2000 Volume 43 Issue 3 Pages
255-258
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The backscattered electron signals from GaAs/Al
xGa
1-xAs superlattice structures are studied with the Monte Carlo simulation of electron scattering. The following results have been obtained. The high resolution observation of GaAs/Al
xGa
1-xAs superlattice structures is achieved by detecting the low-loss backscattered electrons. The minimum detectable mean atomic number variation is 2.7 for 2 nm GaAs/2 nm Al
xGa
1-xAs superlatice with the low-loss backscattered electron signal. This value agrees with the experimental result.
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Keiji TAMURA, Masaaki YASUDA, Kenji MURATA, Masatoshi KOTERA
2000 Volume 43 Issue 3 Pages
259-262
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The electron spin-polarization scanning electron microscope (spin-SEM) uses the polarization of secondary electrons scattered out from magnetic materials to image the surface magnetic structure. The magnetic-domain contrast of the spin-SEM depends on the incident electron energy and the incident angle. We calculated the spin polarization of secondary electrons using a Monte Carlo simulation of electron scattering in magnetic materials based on the single scattering model.
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Yoshinori MORITA, K. Obu-Cann, Heizo TOKUTAKA, Kikuo FUJIMURA, Kazuhir ...
2000 Volume 43 Issue 3 Pages
263-267
Published: March 20, 2000
Released on J-STAGE: April 23, 2010
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The Self-Organizing Map (SOM) developed by Teuvo Kohonen is a powerful tool for Data Mining or knowledge discovery and visualization of high dimensional data. The SOM is being applied to problems of chemical analysis. It simultaneously performs topology preservation of the data space whiles quantizing the data space formed by the input data. The compositions of the unlabeled spectra whose compositions are unknown can be determined using the SOM method which uses the labeled spectra whose compositions are known. In this study, the data mining capabilities of SOM are examined using data from Auger Electron Spectroscopy (AES) and X-ray Photoelectric Spectroscopy (XPS). The results obtained are compared to determine which data is more adaptive to the SOM.
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Akio SUZUKI, Masanari FURIKI, Takanori AOKI, Tatsuhiko MATSUSHITA, Mas ...
2000 Volume 43 Issue 3 Pages
268-272
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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There are many unsettled questions for transparent conducting ITO thin films if used as electronic devices : expensive and weak in durability to reduction gas. In order to improve these disadvantageous points, AZO (ZnO : Al
2O
3) was deposited on the ITO layer by PLD method and laminated transparent conducting films with a structure of ITO + AZO were prepared. It was found that if the film thickness of the upper AZO layer increased, the sheet resistance decreased. At the same time, the increase of averaged transmittance in the visible wavelength region (400700 nm) due to an anti-reflection effect caused by two layer structure of ITO +AZO was recognized. Moreover, it was found from SEM and AFM observations that the surface randomness was improved from 4.54 nm for the ITO single layer to 2.89 nm for the ITO + AZO (120 nm) structure.
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Kojiro ONO, Kunio SAKURADA, Yoshifumi AOI, Eiji KAMIJO
2000 Volume 43 Issue 3 Pages
273-276
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Carbon nitride (CN
x ) thin films were deposited on Corning #7059 glass and Si (100) substrates by pulsed laser deposition (PLD) using a radical beam source. The deposited films were characterized by SEM, XRD, XPS, FT-IR, and Raman spectroscopy. Nitrogen content in the films increased with increasing RF power and N
2 gas pressure in the deposition chamber. A film with N/C atomic ratio of 0.25 was obtained at 400 W of RF power and 1.3 Pa of N
2. N 1s XPS spectra show the existence of N-
sp2C and N-
sp3C bonds in the films. The fraction of N-
sp3C increased with increasing nitrogen content in the film. FT-IR and Raman spectra of the deposited films indicated that N-
spC (N≡C) bond in the deposited films were few. The N/C atomic ratio decreased with increasing heat-treatment temperature. The fraction of N-
sp2C increased with increasing heat-treatment temperature. Heat-treatment of the film caused growth of graphitic domains in the film.
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Tomomi YOSHIMOTO, Kunihiro SAKAMOTO, Tatsuo IWATA
2000 Volume 43 Issue 3 Pages
277-279
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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We have grown a Ge layer on Si (100) substrate and fabricated Au/n-Ge Schottky barrier diode. The Ge layer was grown by solid source molecular beam epitaxy (MBE). The growth procedure consisted of epitaxial growth of Ge layer using Sb as a surface-active-agent (surfactant) and high temperature (620°C) post growth annealing. The crystal structure was evaluated by reflection high-energy electron diffraction (RHEED) and the surface morphology was evaluated by atomic force microscopy (AFM). The RHEED pattern indicated the epitaxial growth of the Ge layer. Examination by AFM revealed some pits on the surface which were considered to be related to dislocation within the sample. The Sb surfactant worked as the donor in the epitaxial layer after the high temperature post growth annealing. The Sb concentration at the surface of the sample was 3 × 10
17 cm
-3. The fabricated device showed the diode characteristics. The leakage current under the reverse bias condition was high and the ideal factor was large. It would seem that the reasons for the high leakage current and the large ideal factor were related to the pits on the surface of the sample.
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Hideki TAKASAKI, Yuichi KAWAMURA, Takahiro KATAYAMA, Akiko YAMAMOTO, N ...
2000 Volume 43 Issue 3 Pages
280-283
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Photoluminescence (PL) properties of In
0.53Ga
0.43As/GaAs
0.5Sb
0.5 type II multiple quantum well (MQW) structures lattice-matched to InP substrates grown by molecular beam epitaxy were studied. It was found that a tunneling assisted type II emission at about 2.3 μm showed a remarkable Si-doping dependence. The PL intensity of the type II emission was found to decrease drastically when the Si-doping concentration exceeds 2 × 10
17 cm
-3, followed by a remarkable increase in the full width at half maximum (FWHM) of the PL spectrum. It became clear that the observed PL intensity decrease and the PL spectral broadening were related to Si-doping into the GaAsSb layers.
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Yoshihiko SHONO, Takashi OKA
2000 Volume 43 Issue 3 Pages
284-287
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Optimum growth conditions of CdS thin films depositted on GaAs (111) B substrate by MBE were investigated. The films were characterized by full width at half maximum (FWHM) of X-ray diffraction (XRD) rocking curve, photoluminescence (PL), and surface morphology by scanning electron microscopy. The FWHM became minimum when the film was grown under the following conditions : The substrate temperature of 280°C, the ratio of molecular beam intensity of S to that of Cd about 1/1.5 and the interruption period of Cd supply for about 0.1 second. Although buffer layer depositted at 150°C for 15 seconds did not seem to affect the FWHM of the film, PL spectra indicated that the film with the buffer layer had better quality than that without the buffer layer. The roughness of the film surface was found to decrease by insertion of the buffer layer.
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Naohiro HORII, Kunio OKIMURA, Akihiro INOUYE
2000 Volume 43 Issue 3 Pages
288-291
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Photochemical dissociation of Tetraethoxysilane (TEOS) used as an organic silicon source in the gas phase was investigated by in-situ mass spectrometry. The vacuum uliraviolet (VUV) sources for inducing photochemical reaction were Xe
2 excimer lamp (172 nm : 7.2 eV) and Hg lamp (185 nm : 6.5 eV). TEOS was dissociated by irradiation of VUV in the gas phase, while releasing alkyl groups such as C
xH
y (x= 1-2, y=2-5). Moreover, almost all Si-O bonds of TEOS were not broken at the energy of Xe
2 excimer light. It has been found that the species produced by photochemical reaction in the gas phase have long lifetime of at least more than 2 minutes. Finally, the film deposited on the MgF
2 window has strong light absorption from visible to ultraviolet region, because the film contains organic compounds.
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Takanori AOKI, Akio SUZUKI, Tatsuhiko MATSUSHITA, Masahiro OKUDA
2000 Volume 43 Issue 3 Pages
292-295
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Thin films of Ga-In oxide (150 nm) have been deposited on glass substrate at room temperature by radio-frequency (rf) magnetron sputtering with two targets of Ga
2O
3 and metallic In, on which rf-powers of 150 W and 6080 W were added respectively. In the oxide films prepared by this method, the difference in the transmittance,
Δ T, between the as-deposited state and the annealed state (400°C × 10 min) was more than 70% in the wavelength region of 350600 nm and at the wavelength of 320 nm, the value of
ΔT of 42% was obtained. It was found from XRD spectra that (1) the In (101) peak was found in the as-deposited state (colored state) and (2) the In
2O
3 (222) peak was formed in the annealed state (transparent state). It was recognized from XPS measurement that the phase transition between the as-deposited state and the annealed state well corresponded to the transition of In (colored state) →In
2O
3 (transparent state). The ability to record on these oxide films without protection layer, using THG of Nd : YAG laser (δ=355 nm, 3 ns) was confirmed. These results will be useful for highly sensitive optical recording films with high density in the ultraviolet-blue wavelenght region.
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Effects of H2 Pressure on Film Properties
Nobuo SAITO, Yasuhiro IGASAKI
2000 Volume 43 Issue 3 Pages
296-298
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Indium nitride thin films have been prepared by an rf magnetron sputtering from In target in N
2 and H
2 gas mixtures. The effects of H
2 partial pressure ratio
R on the structural, optical and electrical properties of the films were investigated. With increasing
R, the deposion rate of the films decreased, and the film structure was changed from crystalline phase with a hexagonal wurtzite structure to amorphous-like one. The bandgap, resistivity, carrier density and mobility also changed depending on
R. In low
R range, the resistivity was increased against
R.
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Atsushi OCHI, Yoshifumi AOI, Eiji KAMIJO
2000 Volume 43 Issue 3 Pages
299-302
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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TiN/SiN
x multilayered thin films were deposited on Corning #7059 glass substrates in an ion beam sputtering (IBS) system with a nitrogen assisted ion beam source. The multilayered thin films were deposited alternately using Ti and Si targets sputtered with the argon ion beam. Layer thickness λ (where λ is the period of the multilayer) ranged from 5 to 160 nm, and total film thickness was 400 nm. The multilayered thin films were examined by X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), micro-hardness, and microindentation hardness. Results are as follows : the high angle XRD showed a preferred orientation of TiN to [200] direction and the small angle XRD exhibited a diffraction pattern of a single-crystal superlattice, although the obtained films consisted of multilayers of microcrystal TiN and amorphous SiN
x. Hardness of the deposited multilayered thin films indicated maximum against the multilayer periods. The maximum knoop hardness value of the obtained TiN/SiN
x multilayered thin film was Hk=2376 kg mm
-2.
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Tatsuo MIGITA, Takeshi TANAKA, Keishi KAWABATA
2000 Volume 43 Issue 3 Pages
303-306
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Tungsten nitride (WN
X) thin films have been prepared using an RF-DC coupled magnetron sputtering system, in which the incident ion energy on the target can be controlled by the target DC bias voltage. The films were applied to Cu/WN
X/Si samples and the obtained Cu (500 nm) /W
2N (25 nm) /Si samples were stable without Cu-Si reaction after annealing at 700°C for 30 min. It was shown that the film composition (N/W) can be controlled by the target DC bias voltage without changing the gas flow ratio (N
2/ (Ar+ N
2)), and the N/W ratio was decreased from 0.8 to 0.2 only by increasing the target DC bias voltage from -100 V to -500 V, respectively, at the N
2/ (Ar + N
2) ratio of 0.2.
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Yasuo MIKAMI, Keiji YAMADA, Akio OHNARI, Toru DEGAWA, Takeshi TANAKA, ...
2000 Volume 43 Issue 3 Pages
307-310
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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RF power and DC bias were simultaneously applied to a Ni target to control the incident ion energy on the target in a magnetron sputtering system equipped with Nd-Fe-B magnet assemblies. When Ni films were prepared at RF input power of 60 W and Ar partial pressure of 6.7×10
-1 Pa and DC bias voltage from -100 V to -500 V, the deposition rate linearly increased from about 9 nm/min to 70 nm/min. It was shown that the film growth coefficient (deposition rate/ion current density) of Ni films depends on the target DC bias voltage.
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Takeshi HARADA, Hiroshi ASAHARA, Tomohiko KAWAMURA, Yutaka SATO, Syogo ...
2000 Volume 43 Issue 3 Pages
311-313
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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In order to obtain high deposition rate of Ni films, we have developed a modified magnetron sputtering cathode configuration with a ferromagnetic Ni target of 100 mm in diameter and 5 mm in thickness. The plasma confinement could be enhanced by providing four special permanent magnets around outside the cathode. Nickel films were prepared at the rf power of 100 to 200 W and the argon gas pressure of 6.7×10
-1 to 8.1×10
-2 Pa. The deposition rate was 14 nm/min, four times as large as that of a conventional magnetron sputtering at an rf power of 100 W and an argon gas pressure of 6.7×10
-1Pa.
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Takashi KUBO, Makoto TANAKA
2000 Volume 43 Issue 3 Pages
314-316
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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In this paper dependence of electrode material on plasma parameter was studied. By changing the electrode material from aluminum to graphite, electron densities were measured with a self-compensated Langmuir probe in an asymmetrical parallel plate radio frequency plasma reactor. The results show that the electron densities with the aluminum cathode are greater than that with the graphite cathode.
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Akiko HIMENO, Shoji TAKAGI, Tetsuji GOTOH
2000 Volume 43 Issue 3 Pages
317-320
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Observation of angle-resolved electron stimulated desorption (ESD) from air-cleaved MgO (001) surface was carried out. Desorbed species have been analyzed by a quadrupole mass spectrometer (QMS) and by time-of-flight (TOF) methods. Most of the desorbed ions originate from adsorbates such as hydroxide or water. The angular dependence of the desorbed ions suggests adosorbed-site and -direction of adsorbates. To investigate some relations of the angular distributions and surface structures, the observation with the atomic force microscope (AFM) of MgO (001) surface was performed. AFM images show <100> aligned giant step lines whose heights are 3 to 4 nm. This result suggest that adsorbates at this giant step sites influence on the angular distributions of ESD ions.
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Yusuke FUJIOKA, Takafumi SATOH, Syouji TAKAGI, Tetsuji GOTOH
2000 Volume 43 Issue 3 Pages
321-324
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Diffusion and desorption of hydrogen in a bulk of molybdenite crystal are studied by measurement of gas emitted from the bulk crystal during cleavage experiment for observation of gases in a bulk, electron stimulated desorption (ESD) for measurement of hydrogen concentration on the surface and temperature programmed desorption (TPD) for estimating ion of an activation energy of diffusion and desorption process. The cleavage and ESD experiments are performed to observe the change of hydrogen concentration in the bulk and on the surface by the sample heating. These experiments show that a mount of hydrogen in the bulk reduces at about 500°C and that the hydrogen concentration on the surface and thermal desorption of hydrogen from the bulk also begin to increase around 500°C. The increase of hydrogen concentration on the surface suggests that the activation energy for thermal desorption is lager than the diffusion energy in the bulk to (0001) surface. However, in this case this may not be applicable because of similar temperature behavior of surface hydrogen and desorbed hydrogen. The mechanism of the diffusion and the desorption process is discussed. The activation energy for the desorption induced by diffusion of hydrogen in the bulk to (0001) surface is about 76 kJ/mol.
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Tomomasa ODA, Yuko HIROHATA, Tomoaki HINO, Seio SENGOKU
2000 Volume 43 Issue 3 Pages
325-328
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Deuterium retention of V-4Cr-4Ti alloy exposed to JFT-2M tokamak environment for 9 months was examined by thermal desorption spectroscopy (TDS). The amount of deuterium retained in V-alloy was approximately 1 wppm, which was one order of magnitude larger than that of 304 SS. After the exposure, deposition of impurities was observed at the surface. The thickness of impurity layer was approximately 200 nm, and the titanium oxide was formed in this layer.
Surface oxidation of V-alloy was conducted in order to reduce the hydrogen absorption. After the oxidation at temperature of 373 K, thick Ti-O layer was formed at the surface. In this case, hydrogen absorption amount was one order of magnitude reduced compared with the case of no oxidation.
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Fumio HIRANO, Yuji YAMAUCHI, Yuko HIROHATA, Tomoaki HINO, Toshiaki SOG ...
2000 Volume 43 Issue 3 Pages
329-332
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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In the divertor of ITER, carbon and tungsten are employed as plasma facing materials. After the machine operation, these materials are mixed as a result of erosion and deposition. Then, both deuterium retention and chemical erosion differ from graphite or tungsten only.
In the present study, carbon tungsten mixed material with different composition was irradiated by deuterium ions, and followed by deuterium retention and chemical erosion were examined. Deuterium retention decreased with increase of tungsten concentration but the decreasing ratio was not so large as predicted. Chemical erosion was considerably reduced as increase of tungsten concentration.
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Kazuto KOIKE, Kuniaki SUEYOSHI, Ken-ichi TANAKA, Shuwei LI, Katsuhiro ...
2000 Volume 43 Issue 3 Pages
333-336
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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This paper describes structural and optical properties of InSb/CdTe single quantum wells (SQWs) grown on GaAs (100) substrates by molecular beam epitaxy. The CdTe films on GaAs contained many defects due to the large lattice mismatch, and In-Te related compounds were easily formed at the InSb/CdTe heterointerface. Photoluminescence and atomic force microscopy measurements revealed that the poor crystallographic quality of the CdTe layer was improved by using a CdTe/MnTe superlattice as a buffer layer. It was also revealed that low-temperature growth combined with a post annealing was effective to improve the InSb/CdTe quality by avoiding the interfacial reaction. As a result, we achieved InSb/CdTe SQWs of which blue shift of absorption edge was reasonably explained by Burstein-Moss shift.
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Sugio WAKO, Md. Golam MOULA, Yuichi OHNO, Tatsuo MATSUSHIMA
2000 Volume 43 Issue 3 Pages
337-340
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The working site providing oxygen ad-atoms reactive towards CO was examined on Pd (110) and Pd (100) from the angular and velocity distributions of desorbing CO
2. The distributions were measured with cross correlation time-of-flight techniques. On Pd (110), abrupt changes were found in both the distributions around a critical CO pressure where the rate-limiting step switched over, indicating that CO
2 formation sites shifted to O
2 dissociation places. On the other hands, no changes were observed on Pd (100), suggesting no shift of CO
2 sites with oxygen coverage.
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Hikaru MISHINA, Takashi MOMOSE, Mitsuhiro TAKAHARA, Yutaka IKUSHIMA, K ...
2000 Volume 43 Issue 3 Pages
341-344
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Generally, contaminations on aluminum surface are hydrocarbons, but they are not clarified yet. So, we applied supercritical fluids (SCF) carbondioxide (CO
2) treatment on aluminum where triglyceride was deposited. Contamination removing rate was evaluated with FT-IR.
(1) The peaks of triglyceride were -CH
3 and -CH
2- at 2920 cm
-1 and 2850 cm
-1, respectively.
(2) Obtained standard lines for evalution are proportional to a square root of contamination of triglyceride in the range from 1% to 30% density. The precision of this standard lines is ±1213%.
(3) Contamination removing rate is in the range of 6798%.Therefore, SCF CO
2 is effective to remove triglyceride on the aluminum surface.
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Takahiro OKADA, Kazumasa ISHIKAWA, Tomoharu TAKANO, Akihiro TANAKA, Ka ...
2000 Volume 43 Issue 3 Pages
345-348
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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In order to study a surface chemical affinity of gas species, we applied thermal desorption spectroscopy (TDS) to modified surfaces of titanium. The surfaces were prepared with different treatments such as buff polishing, chemical polishing, electrical polishing, mechano-chemical polishing and emery polishing with water and carbontetrachloride, respectively as a comparison. Outgassing properties of H2 from polished titanium surfaces have been shown the significant difference on TDS spectra. For higher temperatures than 500°C, TDS spectrum of H2 increased remarkably, and C and O Auger signals decreased.
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Takehide TAMURA, Yuko HIROHATA, Tomoaki HINO
2000 Volume 43 Issue 3 Pages
349-352
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Electron density in nitrogen glow discharge plasma was determined by measuring frequency of plasma oscillation. Plasma oscillation was excited in the glow discharge by using internal cathode placed close to anode. Signal intensity of plasma oscillation was detected by magnetic probe, i.e. magnetic pick-up coil connected to spectrum analyzer.
Spectrum due to the plasma oscillation was clearly observed, and the frequency shifted according to the change of discharge parameters. The electron density measured by the present method was compared with the data of electro-static probe. The present data well agreed with that of the electro-static probe.
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Hiroyuki YOSHIKI
2000 Volume 43 Issue 3 Pages
353-356
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The mode transitions of cylindrical inductively coupled plasmas have been studied on the basis of the equivalent circuit model included both inductive (H-mode) and capacitive (E-mode) coupling branches. The pure inductive discharge is considered as a co-axial one-turn secondary winding of an air-core transformer, while a capacitive current is assumed to flow from a high voltage coil plate to a grounded electrode via a quartz glass and sheaths. The dependence of the plasma density on RF voltage amplitude is calculated as a function of the ratio of angular excitation frequency to electron-neutral collision frequency, ω/ν
c. It is found that the E-H mode jump with the hysteresis phenomenon occurs at ω/ν
c>1, on the other hand the plasma density continuously increases from E- to H-mode at ω/ν
c<1.
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Hiroaki KAWATA, Hidetomo IYANAGA, Takashi MATSUNAGA, Kenji MURATA
2000 Volume 43 Issue 3 Pages
357-360
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Both the current flowing through an antenna coil and the voltage supplied to the coil were measured for Ar inductive coupled plasmas (ICP) at a pressure of 13 Pa. By using the cancel circuit we measured the difference of the antenna coil currents between no plasma load and ICP. The measurement system was improved in order to reduce both radio frequency (RF) noises and waveform distortions. The impedance is presented when the cancel circuit is used. A simple method to obtain the value of the coupling coefficient is presented. The current measured with the cancel circuit could be related to the plasma current much better than that without the cancel circuit. The values of the coupling coefficient increased as the RF power increased, and ranged between 0.3 and 0.5 in our experiment.
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Tomoaki HINO, Koh KANAYA, Yuko HIROHATA
2000 Volume 43 Issue 3 Pages
361-364
Published: March 20, 2000
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Hydrogen retention properties of Li were investigated using a dc glow discharge apparatus with a heater for Li evapo ration. Hydrogen retention of Li after the evaporation was measured based upon a residual gas analysis. In addition, the recovery effects for hydrogen trapping of Li due to baking and He discharge cleaning were examined.
The hydrogen gas pressure largely decreased in the initial discharge stage and then the decreasing ratio became small with the discharge time. The initial decrease is due to the trapping of H
+ and the hydrogen concentration becomes approximately unity in atomic ratio, H/Li, in the ion implantation depth. The slow trapping is presumed to be the diffusion of H into the bulk of Li film.
When the Li evaporation amount was small, both the decrease of hydrogen pressure and the desorption of H
2O were observed. Since the oxide, Li
2O, is partly formed, it is regarded that the reaction, Li
2O+2H
2→H
2O+2LiH, took place.
After the hydrogen discharge for the Li film, the baking with 100°C or He discharge cleaning was conducted, and followed by again the hydrogen discharge was made. Compared with the case of He discharge cleaning, the hydrogen trapping was largely recovered in the case of such the baking.
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Hiroyuki NAKANO, Hideo FURUHASHI, Toshio YOSHIKAWA, Akinori MAEDA, Yos ...
2000 Volume 43 Issue 3 Pages
365-368
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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The vanadyl-phthalocyanine (VOPc) film prepared with MBE on the KBr substrate was treated in organic gas. The thickness of prepared film is 96 nm. The morphology of VOPc film was characterized with opticl absorption spectra in visible and infrared regions (VIS/UV) and SEM. The second and third hormonic generations (SHG and THG) of film was also measured by a Maker fringe method using a Nd-YAG laser. From these results, we clearly indicated that the phase transition of film occurred from a pseudomorphic epitaxy to an epitaxy and also showed that the nonlinear optical properties of VOPc film were improved with the phase transition.
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Takahiro SOUMA, Hideo FURUHASHI, Toshio YOSHIKAWA, Akinori MAEDA, Yosh ...
2000 Volume 43 Issue 3 Pages
369-372
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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Vanadyl-phthalocyanine (VOPc) thin films were prepared on Polyethylene-terephthalate (PET) substrate by a molecular beam epitaxy (MBE). Dependence of morphologies and nonlinear optical properties of the VOPc films on preparing conditions was investigated using UV/VIS spectroscopy and third harmonic generation measurements. VOPc films prepared on the substrate of different temperatures (60°C120°C) showed two structures of a phase I and phase II. We suggested that the threshold temperature for structure changing from phase I to phase II existed at the vicinity of 80°C and also indicated that the TH intensity of VOPc thin film having phase II was more larger than that having phase I.
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Takahiro FUJINO, Yoshimasa MITSUMOTO, Kunio OKA, Takaaki DOHMARU
2000 Volume 43 Issue 3 Pages
373-376
Published: March 20, 2000
Released on J-STAGE: October 20, 2009
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We prepared thin films from poly (methylphenilsilane) (PMPS) and poly (dimethylsilane) (PDMS) by eximer-laser ablation and characterized them as light-emitting material for electroluminescence. The deposited films were characterized by UV, PL (photoluminescence) and FT-IR spectra, and the changes of the targets were examined by PL spectra. The FT-IR spectra of the deposited PDMS films showed that irradiation of PDMS targets at high pulse frequency (100 Hz) gave films that contained very small amount of Si-H groups, meaning that films of the similar chemical composition as the original PDMS were successfully produced. The deposited films that exhibit PL emission around 360 nm at room temperature were obtained from both of the polysilanes. The I-V curve for a LED based on a PDMS films is reported, while its EL emission has not observed yet.
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