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  • Articles  (25)
  • American Institute of Physics (AIP)  (25)
  • 1
    Electronic Resource
    Electronic Resource
    Mechanism of surface-limited release of hydrogen from oxidized metals (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 180-185 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Analysis has been made of the time dependence of surface recombination and release of deuterium from helium-bubble traps in iron with both clean and oxidized surfaces. In both cases second-order kinetics are obeyed over a large range of time scales, including short times when the traps are saturated. We show this is possible only if, in both cases, release is limited by escape from surface sites which have the same energy as the traps. We therefore propose that the oxide represents an additional barrier, but does not alter the energies of sites from which recombination takes place relative to solution sites. We further show that for both iron and stainless steel the prefactor for the recombination rate is about the same for a bare surface and for an oxide layer. Thus effects of the barrier are mostly on the activation enthalpy of release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342567
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  • 2
    Electronic Resource
    Electronic Resource
    Photoluminescence and passivation of silicon nanostructures (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2386-2388 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new method was used to fabricate nanometer-scale structures in Si for photoluminescence studies. Helium ions were implanted to form a dense subsurface layer of small cavities (1–16 nm diameter). Implanted specimens subjected to annealing in a variety of atmospheres yielded no detectable photoluminescence. However, implantation combined with electrochemical anodization produced a substantial blueshift relative to anodization alone. This blueshift is consistent with the quantum confinement model of photoluminescence in porous silicon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113036
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  • 3
    Electronic Resource
    Electronic Resource
    Microstructures of (In,Ga)P alloys grown on GaAs by metalorganic vapor-phase epitaxy (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3077-3087 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructures of metalorganic vapor-phase epitaxy alloys of (In,Ga)P grown on GaAs substrates were examined using transmission electron microscopy. Alloys examined were grown at 600–775 °C on substrates at or near (001) or (113)A using growth rates of 0.69 and 0.17 nm/s. Two common semiconductor alloy phenomenon, ordering and phase separation, were studied over this range of growth conditions. The CuPt-type ordering reflections are sharpest for growth at 675 °C and more diffuse at 600 and 725 °C due to higher densities of antiphase boundaries. Order can be eliminated by growth at 750 °C or above to obtain the highest band gaps and optical emission energies. Detailed investigation of the microstructure for growth at 675 °C indicates that ordered domains are platelets consisting of thin (1–2 nm) lamella on (001) planes that alternate between the two {111}B ordering variants, in agreement with a model proposed by others. We have formed "unicompositional'' quantum wells with sharply defined ordered layers between disordered barrier layers by changing growth temperature, which demonstrates that ordering is determined to a great degree by the conditions during growth. Phase separation is seen for the entire range of growth parameters, independently of ordering; its contrast shows modulations with a variable spacing ranging from a few nanometers to ∼100 nm. Implications of the coexistence of phase separation and ordering for growth models describing these phenomena are discussed. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358659
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  • 4
    Electronic Resource
    Electronic Resource
    Infrared spectroscopy of chemically bonded hydrogen at voids and defects in silicon (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2755-2764 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Chemical bonding of H to displacement defects and internal surfaces in Si has been investigated by infrared-absorption and nuclear reaction analysis techniques. A He implantation/anneal sequence was used to produce faceted voids which are retained to at least 800 °C in a buried layer as revealed by transmission electron microscopy. Hydrogen was injected into void layers by three different methods: ion implantation, plasma exposure, and H2 gas exposure. Infrared absorption by Si-H stretch modes with frequencies characteristic of monohydrides on (100) and (111) surfaces are observed for all methods of H injection, consistent with bonding on faceted void surfaces. Thermal stability of Si-H is higher on void surfaces than on other trapping sites. Displacement defects produced by H-ion implantation trap H but release it upon annealing for retrapping on voids. The Si-H absorption bands with frequencies characteristic of monohydrides on (100) and (111) surfaces anneal in parallel between 600 and 800 °C and in coincidence with the loss of total H measured by nuclear reaction analysis. Moreover, densities comparable to the total H density are estimated for void surface states and for Si—H bonds on void surfaces. It is inferred from these results that bonding of H on the void surfaces is energetically favored over H2 formation in the voids, and it is concluded that the 2.5±0.2 eV determined in a separate study of H release from buried voids is the Si—H bond energy descriptive of both (111) and (100) surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353050
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  • 5
    Electronic Resource
    Electronic Resource
    Precipitate-hardened aluminum alloys formed using pulsed laser deposition (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1116-1122 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Very high-strength alloys of Al have been formed by pulsed laser deposition (PLD) from Al and Al2O3 targets. The deposition is alternated between the two targets, with the ratio of pulses per target controlling the O content, and the amount of each element deposited in a cycle kept low enough that the final material is uniform in composition and has a highly refined microstructure. A fine, uniform dispersion of ∼1-nm-diam γ-Al2O3 precipitates is formed in fcc Al, with an overall composition of up to 33 at. % oxygen. This microstructure is very similar to one that we previously synthesized by using ion implantation of O into Al, where nanoindentation testing revealed yield stresses of ∼1 GPa or more. Nanoindentation testing of these new PLD materials shows yield stresses as high as 5.1 GPa, greatly exceeding the strengths of aerospace Al alloys and even high-strength steels. The key to the properties of these materials is the dispersion of small, hard precipitates spaced only a few Burgers vectors apart; dislocations are apparently unable to cut through and must bow around them. While the nature of ion implantation limits both its cost effectiveness and the thickness of the layers that can be formed, PLD is a completely new approach with major advantages over implantation, including greater control of the composition versus depth, deposition on arbitrary substrates to any thickness, and scalability of the process to larger areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360910
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  • 6
    Electronic Resource
    Electronic Resource
    Interaction of copper with cavities in silicon (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1337-1350 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Copper in Si was shown to be strongly bound at cavities formed by He ion implantation and annealing. Evolution of this system during heating was observed by Rutherford backscattering spectrometry and transmission electron microscopy. Results were mathematically modeled to characterize quantitatively the binding of Cu in the cavities and, for comparison, in precipitates of the equilibrium silicide, η-Cu3Si. Binding of Cu to cavities occurred by chemisorption on the walls, and the binding energy was determined to be 2.2±0.2 eV relative to solution in Si. The heat of solution from the silicide was found to be 1.7 eV, consistent with the published phase diagram. These findings suggest the use of cavities for metal-impurity gettering in Si devices. Hydrogen in solution in equilibrium with external H2 gas displaced Cu atoms from cavity walls, a mechanistically illuminating effect that is also of practical concern for gettering applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361031
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  • 7
    Electronic Resource
    Electronic Resource
    Forces between cavities and dislocations and their influence on semiconductor microstructures (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 3048-3063 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An approximate continuum method for computing the energy of interaction between cavities and strain fields in complex configurations is described and tested by comparison with results for simple, exactly solvable cases. The method is then used to examine semiquantitatively the effective forces between cavities and screw and edge dislocations, taking into account the effects of surface tension and pressurized gas within the cavity. The discussion encompasses not only local interactions involving individual cavities, but also the combined forces acting upon dislocations in the vicinity of multiple cavities and simultaneously within range of external-surface image forces. The results are used to interpret a range of observed microstructures in semiconductors and to assess the possible exploitation of cavity–dislocation binding for dislocation control in Si–Ge heteroepitaxial structures. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371167
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  • 8
    Electronic Resource
    Electronic Resource
    Extreme precipitation strengthening in ion-implanted nickel (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 6547-6556 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Precipitation strengthening of nickel was investigated using ion-implantation alloying and nanoindentation testing for particle separations in the nanometer range and volume fractions extending above 10%. Ion implantation of either oxygen alone or oxygen plus aluminum at room temperature was shown to produce substantial strengthening in the ion-treated layer, with yield strengths near 5 GPa in both cases. After annealing to 550 °C the oxygen-alone layer loses much of the benefit, with its yield strength reduced to 1.2 GPa, but the dual ion-implanted layer retains a substantially enhanced yield strength of over 4 GPa. Examination by transmission electron microscopy showed very fine dispersions of 1–5 nm diameter NiO and γ-Al2O3 precipitates in the implanted layers before annealing. The heat treatment at 550 °C induced ripening of the NiO particles to sizes ranging from 7 to 20 nm, whereas the more stable γ-Al2O3 precipitates were little changed. The extreme strengthening we observe is in semiquantitative agreement with predictions based on the application of dispersion-hardening theory to these microstructures. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371620
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  • 9
    Electronic Resource
    Electronic Resource
    Finite-element modeling of nanoindentation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 1460-1474 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Procedures have been developed based on finite-element modeling of nanoindentation data to obtain the mechanical properties of thin films and ion-beam-modified layers independently of the properties of the underlying substrates. These procedures accurately deduce the yield strength, Young's elastic modulus, and layer hardness from indentations as deep as 50% of the layer thickness or more. We have used these procedures to evaluate materials ranging from ion implanted metals to deposited, diamond-like carbon layers. The technique increases the applicability of indentation testing to very thin layers, composite layers, and modulated compositions. This article presents an overview of the procedures involved and illustrates them with selected examples. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369178
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  • 10
    Electronic Resource
    Electronic Resource
    Deuterium interactions in oxygen-implanted copper (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 311-321 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The interaction of deuterium (D) with Cu2O precipitates in Cu was investigated at temperatures between 300–800 K using ion implantation, nuclear-reaction analysis, and transmission electron microscopy. The exothermic reduction reaction between D and Cu2O to form D2O was found to occur readily at temperatures down to 300 K, with appreciable decomposition of the water and D release occurring only above 600 K. These processes, together with much weaker irradiation-defect trapping in the implanted Cu-Cu2O-D alloy, were quantitatively described by using an advanced transport formalism with independently evaluated reaction and trapping enthalpies. Buried oxide sinks formed by ion implantation were shown to provide an advantageous method of measuring hydrogen permeabilities and chemical potentials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342543
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