摘要 :
We have successfully synthesized homoepitaxial diamond films with atomically flat surface by the microwave plasma chemical vapor deposition (CVD) using an extremely low CH_4/H_2 ratio of CH_4/H_2 gas less than 0.15/100 CH_4/H_2 ra...
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We have successfully synthesized homoepitaxial diamond films with atomically flat surface by the microwave plasma chemical vapor deposition (CVD) using an extremely low CH_4/H_2 ratio of CH_4/H_2 gas less than 0.15/100 CH_4/H_2 ratio and Ib(001) substrates with low misorientation angle (θ_off) less than 1.5 deg . It was found that surface morphologies of the films strongly depend on a growth condition of CH_4/H_2 ratio and θ_off of the substrate and was suggested that the hydrogen etching and the θ_off played an important role for the epitaxial diamond film growth with an atomically flat surface. On the other hand, from the cathodoluminescence spectra and Schottky junction properties of these diamond films with atomically flat surface, it has been clarified that these films have actually a high potentiality for electronic devices.
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1. Differences in the acetylcholine (Ach)-induced endothelium-dependent relaxation and hyperpolarization of the mesenteric arteries of Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) were studied. ...
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1. Differences in the acetylcholine (Ach)-induced endothelium-dependent relaxation and hyperpolarization of the mesenteric arteries of Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) were studied. 2. Relaxation was impaired in preparations from SHRSP and tendency to reverse the relaxation was observed at high concentrations of Ach in these preparations.
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Elastic constant measurements down to 0.48 K and in magnetic fields up to 11 T were performed on a single crystal of the filled skutterudite compound PrOs_4As_(12). The longitudinal C_(L111) = C_B+4C_(44)/3 mode shows Curie-type s...
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Elastic constant measurements down to 0.48 K and in magnetic fields up to 11 T were performed on a single crystal of the filled skutterudite compound PrOs_4As_(12). The longitudinal C_(L111) = C_B+4C_(44)/3 mode shows Curie-type softening below ～25 K, whi
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Generalization and consolidation of scaling laws of potential formation and associated effects are investigated in the GAMMA 10 tandem mirror. The scaling covers over representative tandem-mirror operational modes, characterized i...
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Generalization and consolidation of scaling laws of potential formation and associated effects are investigated in the GAMMA 10 tandem mirror. The scaling covers over representative tandem-mirror operational modes, characterized in terms of (ⅰ) a high-potential mode having kV -order plasma confining potentials, and (ⅱ) a hot-ion mode yielding fusion neutrons with 10-20 keV bulk-ion temperatures. A novel proposal of extended consolidation and generalization of the two major theories of (ⅰ) Cohen's strong electron cyclotron heating (ECH) theory for the formation physics of plasma confining potentials, and (ⅱ) the generalized, Pastukhov theory for the effectiveness of the produced potentials on plasma confinement has been made through the use of the energy-balance equation. This proposal is then followed by the verification on the basis of experimental data from the above two representative modes in GAMMA 10. The importance of the validity of this proposed consolidation is highlighted by a possibility of extended capability inherent in Pastukhov's prediction of requiring ion-confining potential (φ_c) of 30 kV for a fusion Q value of unity through an application of Cohen's potential formation method. In addition to the above potential physics scaling, an externally controllable parameter scaling including ECH powers for potential formation is investigated: The construction of the (φ_c formation scaling with both plug and barrier ECH is carried out. Data onφ_c [kV] (or equivalently <φ_b with n_p/n_c from the strong ECH theory) as a function of externally controllable plug and barrier ECH powers, (P_(PECH)[kW] and P_(BECH)[kW], respectively), and n_c [10~(18)m~(-3)] are summarized as follows: φ_c=1.0x10~(-4) (1+5.0x10~(-3)xP_(BECH)~(1.04+-0.02)) P_(PECH)~(1.73+-0.02) x[c (n_p/n_c)~(2/3)-1] exp [-(0.33+-0.05) n_c]. Here, c=9-11 and 7-9 for the hot-ion and high-potential modes, respectively. The present paper covers the following updated results: (ⅰ) A verification of our novel proposal for potential formation and effects is carried out so as to consolidate two major (Pastukhov's and Cohen's) theories by the use of the "third mode" with the central ECH. The validity of the theory provides a future scenario for combining present representative modes so as to upgrade to hot-ion plasmas with high potentials, (ⅱ) A novel efficient scaling of φ_c formation with both plug and barrier ECH is summarized. The combination of the physics scaling of (ⅰ) with the externally controllable practical power scaling of (ⅱ) provides a scalable way far the future tandem-mirror researches.
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High-dielectric constant (high-k) gate materials, such as HfSiO_x and HfAlO_x, fabricated by atomic-layer deposition techniques were characterized using monoenergetic positron beams. Measurements of the Doppler broadening spectra ...
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High-dielectric constant (high-k) gate materials, such as HfSiO_x and HfAlO_x, fabricated by atomic-layer deposition techniques were characterized using monoenergetic positron beams. Measurements of the Doppler broadening spectra of annihilation radiation and the lifetime spectra of positrons indicated that positrons annihilated from the trapped state by open volumes that exist intrinsically in amorphous structures of the films. The size distributions of the open volumes and the local atomic configurations around such volumes can be discussed using positron annihilation parameters, and they were found to correlate with the electrical properties of the films. We confirmed that the positron annihilation is useful technique to characterize the matrix structure of amorphous high-k materials, and can be used to determine process parameters for the fabrication of high-k gate dielectrics.
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The mechanical properties in two commerial Mg-Al_Zn alloys were investigated at elevated temperatures,. The alloys were examined for tensile tests and then charactacterized. The deformation mechanism in two alloys varied with thei...
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The mechanical properties in two commerial Mg-Al_Zn alloys were investigated at elevated temperatures,. The alloys were examined for tensile tests and then charactacterized. The deformation mechanism in two alloys varied with their grain sizes. A coarse-grained(>100) Mu m) alloy exhibited a strain rate sensitivity of ~0.33, and fractured with significant development pf necking. On the other band, finer-frained alloys with grain sizes less than 20 mu m exhibited high strain rate sensitivity ~ 0.5, and failed with brittle fracture corresponding to the cavity growth. The grain size dependence on the tensile properties was discussed to apply these alloys for superplastic forming.
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Second generation proximity x-ray lithography (PXL-Ⅱ), which uses shorter incident x-ray wavelengths and resist materials, is expected to be a candidate for next generation lithography. In the PXL-Ⅱ technique, the x-ray waveleng...
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Second generation proximity x-ray lithography (PXL-Ⅱ), which uses shorter incident x-ray wavelengths and resist materials, is expected to be a candidate for next generation lithography. In the PXL-Ⅱ technique, the x-ray wavelength absorbed in the resist becomes shorter, but degradation of the pattern quality due to secondary electron blur has not been sufficiently evaluated. In this article, we present our investigation of the secondary electron blur's suppression in Br-containing resist using a lithographic simulator and a Monte Carlo simulator for electron scattering. By introducing the Br element into resist materials, the electron stopping power improves. In addition, secondary electron blur is suppressed in regions with wavelengths shorter than that of the Br absorption edge. In order to evaluate pattern resolution, the image contrast of the lateral absorbed image in the resist is defined. We found that image contrast is improved in Br-containing resist for the wavelength range down to about 4.5 A, which is suitable for PXL-Ⅱ. We also show that it should be possible to extend PXL-Ⅱ for resolutions of less than 40 nm at a narrower gap.
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High-quality ZnO films were successfully prepared on Si wafers by low-pressure MO-CVD using zinc acetylacetonate (Zn(C_5H_4O_2)_2) and oxygen. The c-axis oriented ZnO films were grown on p-type Si wafers at temperature of 520℃ wi...
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High-quality ZnO films were successfully prepared on Si wafers by low-pressure MO-CVD using zinc acetylacetonate (Zn(C_5H_4O_2)_2) and oxygen. The c-axis oriented ZnO films were grown on p-type Si wafers at temperature of 520℃ with ZnO buffers layers deposited by RF sputtering. Although, the ZnO layer deposited by sputtering has a poor c-axis orientation, the films prepared by MO-CVD on the ZnO buffer layer shows a sharp X-ray diffraction peak at 34.4° corresponding to the (0002) of hexagonal ZnO. Room temperature photoluminescence spectrum of the all film exhibits a strong peak consisted of near-band edges emission at 378 nm. Current-voltage characteristics of the ZnO(n)/Si(p) heterojunction exhibits non-linear and rectifying characteristics with a small current leakage in the reverse direction. A dark-blue light was clearly observed around the periphery of the top Al electrode by applying forward bias voltages.
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Detailed plasma-physics investigations by the use of x-ray-tomography data supported by the fundamental theoretical studies of x-ray-detector responses enhance the importance of x-ray diagnostics for fusion-plasma analyses. Howeve...
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Detailed plasma-physics investigations by the use of x-ray-tomography data supported by the fundamental theoretical studies of x-ray-detector responses enhance the importance of x-ray diagnostics for fusion-plasma analyses. However, degradation in responses of semiconductor x-ray detectors after fusion-produced neutron exposure still remains one of the most serious problems in recent fusion experiments even at this time. For the purpose of investigating and characterizing neutron effects on semiconductor x-ray detectors, detection characteristics of n-type silicon semiconductor detectors which are similar to those utilized for x-ray-tomography detectors in the Joint European Torus (JET) tokamak, are studied by the use of synchrotron radiation from a 2.5-GeV positron storage ring at the Photon Factory. The fusion neutronics source (FNS) of Japan Atomic Energy Research Institute is employed as well-calibrated deuterium-tritium (D-T) neutron source with fluences from 10~(13) to 10~(15) neutrons/cm~2 onto these semiconductor detectors. Degradation in x-ray responses with increasing neutron fluences has been reported; however, our recent detailed investigations of detector responses show nonlinear dependence as a function of the neutron fluence.
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The direct detailed observations of temporally and spatially resolved plasma behavior of a magnetohydrodynamic (MHD) anchor stabilization for central-cell plasmas are carried out by the use of our newly developed semiconductor x-r...
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The direct detailed observations of temporally and spatially resolved plasma behavior of a magnetohydrodynamic (MHD) anchor stabilization for central-cell plasmas are carried out by the use of our newly developed semiconductor x-ray detector arrays installed in both central-cell and anchor regions of the GAMMA 10 tandem mirror. In comparison to the previous reports, the present x-ray observations directly clarify an unsolved issue of the behavior of the internal core-plasma structure during the MHD destabilization experiments. The present x-ray analyses by the use of our proposed method with our developed matrix-type semiconductor detector are, therefore, characterized in terms of providing the direct detailed "visible" structural information on the interior core-plasma behavior during the period with the MHD instability, as well as showing the important role of the minimum-B inboard anchor in the MHD plasma stabilization in GAMMA 10.
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