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  • 1
    Electronic Resource
    Electronic Resource
    Formation energies and relative stability of perfect and faulted dislocation loops in silicon (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 8420-8428 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of the relative thermal stability of perfect and faulted dislocation loops formed during annealing of preamorphized silicon wafers has been carried out. A series of transmission electron microscopy experiments has been designed to study the influence of the ion dose, the annealing ambient and the proximity of a free surface on the evolution of both types of loops. Samples were implanted with either 150 keV Ge+ or 50 keV Si+ ions to a dose of 2×1015 cm−2 and annealed at 900 °C in N2, N2O, and O2. The calculations of formation energy of both types of dislocation loops show that, for defects of the same size, faulted dislocation loops (FDLs) are more energetically stable than perfect dislocation loops (PDLs) if their diameter is smaller than 80 nm and vice versa. The experimental results have been analyzed within the framework of the Ostwald ripening of two existing populations of interstitial defects. It is found that the defect ripening is nonconservative if the surface is close to the end of range defect layer or if the sample is oxidized during annealing. In both cases, the knowledge of the formation energy of both types of dislocation loops allows a realistic estimate of the interstitial flux towards and from the surface, respectively, during annealing, in agreement with the experimental results. During a conservative ripening process, a direct correspondence exists between the formation energy of the two defect families and the number of atoms bound to them. In this case, the relative stability of FDLs and PDLs depends on the initial supersaturation of Si interstitial atoms created during implantation. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373557
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  • 2
    Electronic Resource
    Electronic Resource
    Transient enhanced diffusion of boron in presence of end-of-range defects (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 2855-2861 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The presence of a supersaturation of Si self-interstitials in ion implanted silicon has been shown to be the origin of several physical phenomena such as transient enhanced diffusion (TED) of boron, the formation of extended defects at the projected range of implanted atoms at doses below the amorphization threshold, and the formation of end-of-range (EOR) defects in the case of a preamorphization stage. In this article, we discuss the relation between boron anomalous diffusion and end-of-range defects. Modeling of the behavior of these defects upon annealing allows one to understand why and how they affect dopant diffusion. This is possible through the development of the Ostwald ripening theory applied to extrinsic dislocation loops. This theory is shown to give access to the variations of the mean supersaturation of Si self-interstitial atoms between the loops and also to be responsible for anomalous diffusion. This initial supersaturation is, before annealing, at least five decades larger than the equilibrium value and exponentially decays with time upon annealing with activation energies that are the same as the ones observed for TED. It is shown that this time decay is precisely at the origin of the transient enhancement of boron diffusivity through the interstitial component of boron diffusion. Side experiments shed light on the effect of the proximity of a free surface on the thermal behavior of EOR defects and allow us to quantitatively describe the space and time evolutions of boron diffusivity upon annealing of preamorphized Si layers. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366117
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  • 3
    Electronic Resource
    Electronic Resource
    An analysis of the destabilizing curvature effects on the turbulent flow over a rotating cylinder (1999)
    Springer
    The European physical journal 8 (1999), S. 463-475 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 47.27.-i Turbulent flows, convection, and heat transfer - 47.32.-y Rotational flow and vorticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: An analysis based on the available experimental data and second-order closures is made for a turbulent shear flow over a rotating cylinder in a quiescent fluid. The near-wall behaviour of the non-linear model for the pressure-strain correlation proposed by Speziale, Sarkar and Gatski [J. Fluid Mech. 245, 227 (1991)] is enlarged; and the methodology proposed by Lai and So [J. Fluid Mech. 221, 641 (1990)] is adopted to take into account the wall-effects. The radial profile of the curvature parameter, Rs, is examined in connection with the logarithmic law. It is shown that the log-layer is associated to the region where the mean velocity profile, V, is related to the power of the radial distance as Computations reveal that this region corresponds to the state with the most destabilizing curvature effects; which can be chararacterized by the minimum value of the parameter B c =2R s (1+2R s ), and not that one of the parameter B=2R s (1+2R s )/(1+R s )2 firstly introduced by Bradshaw [J. Fluid Mech. 36, 171 (1969)] and extensively used to characterize the turbulence structure in curved flows.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100510050713
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