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  • 1
    ISSN: 1432-0630
    Keywords: 79.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The application of a retarding-dispersive energy analyzer as the pre-filter of a quadrupole mass analyzer has made it possible to combine a standard high-speed Secondary Ion Mass Spectrometer (SIMS) and a high-resolution secondary-ion energy analyzer into one instrument. Data taken with this instrument indicate the presence of very significant high-energy tails in the energy distribution of all observed secondary ions, even with relatively low (2 keV) primary ion energies. The shape of the energy distribution varies widely from element to element, for atomic compared to molecular species sputtered from a clean metal surface, and depends, for a given species sputtered from a metal surface, on the degree of surface oxidation. The variations established in the present work are large enough to introduce in many cases substantial discrepancies between published values of both relative ion sputtering yields and surface elemental concentrations and values obtained by considering the complete energy distribution. Methods of obtaining accurate secondary ion yields by integrating the energy distribution are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrananocrystalline diamond (UNCD) films, grown using microwave plasma-enhanced chemical vapor deposition with gas mixtures of Ar–1%CH4 or Ar–1%CH4–5%H2, have been examined with transmission electron microscopy (TEM). The films consist of equiaxed nanograins (2–10 nm in diameter) and elongated twinned dendritic grains. The area occupied by dendritic grains increases with the addition of H2. High resolution electron microscopy shows no evidence of an amorphous phase at grain boundaries, which are typically one or two atomic layer thick (0.2–0.4 nm). Cross-section TEM reveals a noncolumnar structure of the films. The initial nucleation of diamond occurs directly on the Si substrate when H2 is present in the plasma. For the case of UNCD growth from a plasma without addition of H2, the initial nucleation occurs on an amorphous carbon layer about 10–15 nm thick directly grown on the Si substrate. This result indicates that hydrogen plays a critical role in determining the nucleation interface between the UNCD films and the Si substrate. The relation between diamond nuclei and Si is primarily random and occasionally epitaxial. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 301-303 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Superconducting films of YBa2Cu3O7−δ have been synthesized in a novel ion beam sputter deposition system which features a rotating target holder with BaO2, CuO, and Y2O3 as the sputtering targets. The dwell time of the ion beam on each oxide target is determined by a computer-controlled feedback loop using the signal from a programmable quartz crystal resonator. The sputtered fluxes of all film components originate from the same spatial location, ensuring homogeneous film composition. The results presented demonstrate for the first time an automated ion beam sputter deposition system with the capability of producing high Tc superconducting films by controlled sputtering of either elemental metallic components or oxide precursors. The concept may be extended to include processes such as patterning, production of layered structures (junctions), and film encapsulation necessary for microcircuit manufacturing based on high Tc superconducting films.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 3437-3439 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A processing route has been developed to grow bundles of carbon nanotubes on substrates from methane and hydrogen mixtures by microwave plasma-enhanced chemical vapor deposition, catalyzed by iron particles reduced from ferric nitrate. Growth takes place at about 900 °C leading to nanotubes with lengths of more than 20 μm and diameters on the nanometer scale. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ferroelectric lead zirconium titanate [Pb (ZrxTi1−x)O3] (PZT) thin films have been synthesized by using an automated laser ablation deposition technique with a capability for layer-by-layer or simultaneous deposition of elemental film constituents. The technique is suitable for producing multicomponent and/or multilayered thin films with controlled stoichiometry, such as high-temperature superconductor, ferroelectric, and electro-optic thin films. PZT films were synthesized on MgO (100) by either sequential deposition of layers of ZrO2, TiO2, and PbO, produced by laser ablation of ZrO2, TiO2, and PbO targets, or by simultaneous deposition of all species from ablation of stoichiometric or PbO-rich PZT targets. Films were deposited at 200 °C and subsequently annealed at 600 °C for different periods of time. The orientation, microstructure, surface topography, and composition of the films were characterized by x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Rutherford backscattering spectrometry, respectively. As-deposited layer films consists of highly oriented (001) PbO layers, from which highly oriented (110) PZT films are produced after postdeposition annealing. On the other hand, laser ablation of bulk PZT targets yields amorphous as-deposited films, which evolve into highly oriented (100) PZT films after postdeposition annealing. Preliminary electrical characterization of the PZT films included polarization hysteresis, fatigue, conductivity (ac and dc), and capacitance versus voltage measurements. From the initial electrical measurements, it appears that the remnant polarization of the layered PZT films is similar to that of the films produced by laser ablation of bulk PZT targets.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2958-2967 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrananocrystalline diamond (UNCD) films 0.1–2.4 μm thick were conformally deposited on sharp single Si microtip emitters, using microwave CH4–Ar plasma-enhanced chemical vapor deposition in combination with a dielectrophoretic seeding process. Field-emission studies exhibited stable, extremely high (60–100 μA/tip) emission current, with little variation in threshold fields as a function of film thickness or Si tip radius. The electron emission properties of high aspect ratio Si microtips, coated with diamond using the hot filament chemical vapor deposition (HFCVD) process were found to be very different from those of the UNCD-coated tips. For the HFCVD process, there is a strong dependence of the emission threshold on both the diamond coating thickness and Si tip radius. Quantum photoyield measurements of the UNCD films revealed that these films have an enhanced density of states within the bulk diamond band gap that is correlated with a reduction in the threshold field for electron emission. In addition, scanning tunneling microscopy studies indicate that the emission sites from UNCD films are related to minima or inflection points in the surface topography, and not to surface asperities. These data, in conjunction with tight binding pseudopotential calculations, indicate that grain boundaries play a critical role in the electron emission properties of UNCD films, such that these boundaries: (a) provide a conducting path from the substrate to the diamond–vacuum interface, (b) produce a geometric enhancement in the local electric field via internal structures, rather than surface topography, and (c) produce an enhancement in the local density of states within the bulk diamond band gap. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrananocrystalline diamond (UNCD) films with up to 0.2% total nitrogen content were synthesized by a microwave plasma-enhanced chemical-vapor-deposition method using a CH4(1%)/Ar gas mixture and 1%–20% nitrogen gas added. The electrical conductivity of the nitrogen-doped UNCD films increases by five orders of magnitude (up to 143 Ω−1 cm−1) with increasing nitrogen content. Conductivity and Hall measurements made as a function of film temperature down to 4.2 K indicate that these films have the highest n-type conductivity and carrier concentration demonstrated for phase-pure diamond thin films. Grain-boundary conduction is proposed to explain the remarkable transport properties of these films. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2529-2531 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have recently developed a mass spectroscopy of recoiled ions technique which is suitable for monolayer-specific surface analysis of thin films during growth. We present initial results using this technique to study the effect of different bottom electrode layers on metallic species and oxygen incorporation in the early stages of SrBi2Ta2O3 (SBT) film growth via ion beam-sputter deposition. The work discussed here has been focused on studying the incorporation of Sr, Bi, and Ta during growth of SBT on Pt/Ti/SiO2/Si, Pt/MgO, Ti, and Si substrates. We found that the incorporation of Bi in sputter-deposited SBT films depends critically on the bottom electrode surface composition and the growth temperature. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In situ, real-time studies of layered perovskite SrBi2Ta2O9 (SBT) film growth processes were performed using a time-of-flight ion scattering and recoil spectroscopy (TOF ISARS) technique. These studies revealed two important features related to the synthesis of SBT films via ion-beam sputter-deposition, namely: (a) atomic oxygen originating from a multicomponent SBT target during the sputtering process is incorporated in the growing film more efficiently than molecular oxygen; and (b) the SBT surface appears to be terminated in an incomplete (Bi2O2)2+layer with a top surface of oxygen atoms, which may be responsible for the high resistance to polarization fatigue exhibited by Pt/SBT/Pt capacitors. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 239-241 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Superconducting pressed pellets of YBa2Cu3O7 (Tc=90 K), which were used as ablation targets for laser-induced vapor deposition of high Tc(85 K) superconducting thin films, have been analyzed by secondary electron microscopy, scanning Auger microscopy, energy dispersive x-ray analysis, and x-ray diffractometry. The elemental distribution of Y, Ba, and Cu appears reasonably uniform at depths corresponding to that probed by energy dispersive x-ray analysis (∼1 μm). However, scanning Auger microscopy analysis of the laser-impacted area shows a significant depletion of Cu and spatial redistribution of Y, Ba, Cu, and O on the target surface. X-ray diffractometry of the laser-impacted area shows the appearance of a new broad peak at a diffraction angle 2θ=29.7°, characteristic of BaY2O4 and a poorly defined peak at 2θ=29.3°, that can be attributed to BaCuO2. A possible influence of the laser-induced bulk superconductor compositional changes on the film composition is discussed in relation to recently reported experimental results on laser vapor deposition of high Tc films.
    Type of Medium: Electronic Resource
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