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  • Articles: DFG German National Licenses  (52)
Source
  • Articles: DFG German National Licenses  (52)
Material
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5646-5649 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Morphologies of Si surfaces treated with aqueous solutions of hydrofluoric acid (HF) and ammonium fluoride (NH4F) have been investigated using surface infrared spectroscopy. We confirm that HF-treated Si(111) surfaces are terminated with a monohydride (Si—H), dihydride (Si—H2), and trihydride (Si–H3), whereas NH4F-treated Si(111) surfaces are dominantly terminated with Si—H. For Si(100), treatment in NH4F produces a surface for which the dihydride mode is enhanced compared to HF treatment, suggesting that surface Si—Si bonds on Si(100) are readily cleaved in a NH4F solution to generate a dihydride Si. The effect of varying the HF concentration on the morphology of HF-treated Si(100) surfaces is investigated. It is demonstrated that 5% HF treatment produces Si(100) surfaces which have a larger density of surface Si—Si bonds than 50% HF or 0.5% HF treatment.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2488-2491 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Si(111) surface treated in a saturated solution of NH4F has been investigated using photoemission spectroscopy with synchrotron radiation and surface infrared spectroscopy (SIS) in the multiple internal reflection mode. Photoemission and SIS data clearly demonstrate that the NH4F-treated Si(111) surface is dominantly terminated with the monohydride Si (Si-H) oriented perpendicular to the surface and is free from silicon oxide. It is suggested that the absence of silicon oxide is closely related to the atomic flatness of this surface.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 1023-1028 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Large area ion sources have been used in ion doping systems in the field of LCD production. In these ion sources good uniformity and wide dynamic range in beam current are both required to achieve the good dose uniformity in wide dose range. A new ion source which uses dc arc discharge with three filaments, each of which is controlled individually, is now in the production lines instead of the conventional rf discharge type. Better than 5% of beam uniformity across 600 mm is achieved by an automated feedback control using beam profile data taken by a built-in beam profiler in less than 10 s from arc ignition. Another emerging requirement is high beam purity, for the ion beams from these ion sources are used without mass analysis. The hydrogen ion fraction was successfully reduced by magnetically retarding the hydrogen ions to less than 5%. A large area ion source having a newly designed mass separating structure is developed. The structure is comprised of a permanent magnet array and a beamlet scanner just after the multiple-slot beam extraction electrode system. All the unwanted ion species in the beam can be eliminated to a good level. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 1173-1175 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new-concept plasma grid, named frame-cooling-type plasma grid, was developed for a long pulse operation of a cesium-seeded volume H− ion source. The frame-cooling-type plasma grid was tested using a long pulse H− ion source. The grid has a kind of bellows structure that acts as thermal insulator to keep the surface temperature at an optimum value for H− ion production. It was confirmed that the temperature was kept at over 250 °C, an optimum temperature for the cesium effect, in steady-state operations with the plasma grid cooled by room-temperature water. Using the plasma grid, a maximum H− ion beam of 40 keV, 600 mA (16 mA/cm2) for a long pulse operation of 90 s was generated successfully. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1051-1053 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high brightness negative hydrogen ion source has been developed for a high intensity proton linear accelerator. The ion source is volume production type. Negative ions are generated in a magnetically filtered multicusp plasma generator. The negative ion production is enhanced by seeding a small amount of cesium into the plasma generator. A negative hydrogen ion beam of 36 mA was extracted from a single aperture at an acceleration voltage of 50 kV. To obtain a higher ion beam current, the focusing of beamlets extracted from the multiaperture grid has been demonstrated with an aperture displacement technique. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 947-949 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Grid power loading in a multistage, multigrid accelerator was calorimetrically measured using the Japan Atomic Energy Institute 400 keV accelerator. This is the first result on the grid power loading in the multistage accelerator. It is turned out that the extracted electrons are effectively suppressed in an extractor. The leakage of the electrons extracted from the source plasma to the first acceleration grid, the second grid and the grounded grid were no more than 0.8%, 0.2%, and nearly zero of the extracted electron current, respectively. Under the optimum beam optics that gives the lowest beam divergence, the power loadings of the acceleration grids were dominated by acceleration of the stripped electrons. At a typical source operating pressure of 0.3 Pa, the power loadings of a first acceleration grid, a second acceleration grid, and a grounder grid were 3.4%, 5.0%, and 2.8% of the total beam power, respectively. From the comparison with the calculated grid power loading, it is found that the stripped electrons can be intercepted by intermediate acceleration grids before fully accelerated. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The first results of the performance test of the large negative ion source for a JT-60U negative-ion-based neutral beam injector (N-NBI) are presented. The ion source consists of a cesium seeded multicusp plasma generator, where negative ions are produced via volume and surface processes, a 110 cm×45 cm multiaperture extractor, and a three-stage electrostatic accelerator. After negative ion production and voltage holding tests in test stands, the ion source was installed in the N-NBI system and the full power test began. Up to now, the ion source has produced 400 keV, 5.9 A (2.4 MW) D− ion beams, the world highest D− current and beam power, with a pulse duration of 0.1 s. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The acceleration grid heat load was measured for the first time as a function of the bias voltage, with the source filling gas pressure using a 400 keV three-stage electrostatic accelerator with multi-aperture. The bias voltage dependence shows that leakage of electrons extracted with H− ions to an accelerator is suppressed efficiently in the extractor. The heat load is mainly due to electrons stripped from H− ions at a high source pressure. The heat load due to the stripped electrons could be suppressed effectively by reducing the source pressure. It was confirmed experimentally that reduction of the source pressure is important to suppress the electron acceleration. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Technologies producing high power negative ion beams have been highly developed over the years at Japan Atomic Energy Research Institute for use in neutral beam injectors for heating the thermonuclear fusion plasmas. At present, it is possible to produce multiampere H−/D− ion beams quasicontinuously at energies of more than a few hundred keV with a good beam optics of beamlet divergence of a few mrad. Based on these technologies, two research and development projects have been initiated; one is to develop a 22 A/500 keV/10 s D− ion source for the neutral beam injector for JT-60U, and the other is to develop a 1 A/1 MeV/60 s H− ion source to demonstrate high current negative ion acceleration up to the energy of 1 MeV, the energy required for the neutral beam injector for the International Thermonuclear Experimental Reactor. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4988-4993 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Adsorption of PH3 onto Si(100) and hydrogen desorption therefrom at various adsorption temperatures Ta have been investigated by the temperature-programmed-desorption (TPD) method, which includes measurements on repeatedly adsorbed surfaces to obtain the surface phosphorus coverage. The TPD peak showed a shift toward higher temperatures for Ta above 400 °C, which can be correlated to the onset of the hydrogen desorption and a resultant concentrated adsorption of the phosphorus atoms during exposure. A support for this correlation is given by further analysis of the TPD line shape, which clarified that surface phosphorus restricts hydrogen desorption both by suppressing hydrogen association and by increasing the desorption energy. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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