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  • 1
    Electronic Resource
    Electronic Resource
    Diffusion of dopants in B- and Sb-delta-doped Si films grown by solid-phase epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3150-3155 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The diffusion of δ-function-shaped B- and Sb-dopant spikes in thin Si films grown by solid-phase-epitaxy [(SPE), growth of amorphous film by molecular-beam epitaxy (MBE) at room temperature and subsequent regrowth in situ] during annealing in vacuum is compared to diffusion in films grown by low-temperature (LT) MBE. Diffusion temperatures from 750 to 900 °C, and two-dimensional concentrations of 0.7–1.6×1014 cm−2 have been investigated. The diffusive behavior of dopants in SPE films is found to be qualitatively different from that in films grown by LTMBE. This is related to the vacancylike defects that are intrinsic to growth by SPE but not to growth by LTMBE. Dopant profiles widen significantly during SPE regrowth, making the achievement of δ-function dopant spikes impossible. After a vacuum anneal the diffusion coefficients for both n- and p-type dopants are lower in SPE films than the corresponding values in films grown by LTMBE by up to one order of magnitude. The diffused depth profile of the dopant in LTMBE films shows the characteristic deviation from a pure Gaussian that is expected due to the concentration dependence of diffusion, i.e., a flat top and steep shoulders. In contrast, dopant depth profiles of SPE-grown material show after diffusion a central spike and relatively flat shoulders. The width of the central spike is, after an initial transient that it was not possible to resolve, independent of diffusion time and temperature. This indicates that the SPE material is defective, with the defects acting as traps during diffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354583
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  • 2
    Electronic Resource
    Electronic Resource
    Optical doping of waveguide materials by MeV Er implantation (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 3778-3784 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Implantation of MeV erbium ions into micron-thick silica and phosphosilicate glass films and 1200-A(ring)-thick Si3N4 films is studied with the aim of incorporating the rare-earth dopant on an optically active site in the network. Implantation energies and fluences range from 500 keV to 3.5 MeV and 3.8×1015 to 9.0×1016 ions/cm2. After proper thermal annealing, all implanted films show an intense and sharply peaked photoluminescence spectrum centered around λ = 1.54 μm. The fluorescence lifetime ranges from 6 to 15 ms for the silica-based glasses, depending on annealing treatment and Er concentration. Silicon nitride films show lower lifetimes, in the range 〈0.2–7 ms. Annealing characteristics of all materials are interpreted in terms of annealing of ion-induced network defects. These defects are identified using photoluminescence spectroscopy at 4.2 K. Concentration quenching, diffusion and precipitation behavior of Er is also studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349234
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  • 3
    Electronic Resource
    Electronic Resource
    The effect of ion implantation and solute atoms on the interdiffusion in amorphous Si/Ge multilayers (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 6430-6436 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous Si/amorphous Ge multilayers were prepared by ion beam sputtering. Silicon, boron, gold, or oxygen atoms were introduced into the Si/Ge multilayers by ion implantation or during the sputtering deposition. Diffusion or ion mixing lengths were determined by measuring the decrease in the intensity of the first-order x-ray diffraction peak resulting from the composition modulation. Annealing of Si-implanted samples showed that after relaxation the diffusivity appeared unaffected by the implantation process. Annealing of the multilayers containing B or Au showed that the interdiffusion of Si and Ge in their amorphous phase can be enhanced by doping, while O implantation showed no effect. The enhancement factor is independent of the degree of structural relaxation, as observed by the decrease of diffusivity with annealing time, of the amorphous phase. A model is proposed that describes this behavior in terms of electronic effects, introduced by dopants, on the pre-existing structure defects governing interdiffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348848
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  • 4
    Electronic Resource
    Electronic Resource
    X-ray measurements of ion mixing in amorphous Si/Ge artificial multilayers (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4556-4560 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous Si/Ge artificial multilayers with a repeat length around 60 A(ring) have been partially mixed with 1.5-MeV Ar+ ions at temperatures in the range 77–673 K. The diffusive component of the square of the mixing length, obtained by subtracting out the ballistic contribution, does not depend on the dose rate at a given dose, and shows an Arrhenius-type temperature dependence with activation enthalpies between 0.13 and 0.22 eV. Possible mechanisms for migration and annihilation processes of defects are discussed to understand these low activation enthalpies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346161
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  • 5
    Electronic Resource
    Electronic Resource
    Ion irradiation damage in Er-doped silica probed by the Er3+ luminescence lifetime at 1.535 μm (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 1669-1674 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of MeV ion irradiation damage on the luminescence lifetime of erbium-doped silica glass films has been studied. The 10-μm-thick films were first implanted with 3.5 MeV Er at a fluence of 5×1015 cm−2. When optically pumped at 488 nm, the films show a clear photoluminescence spectrum centered around 1.535 μm, corresponding to the 4I13/2→4I15/2 transition of Er3+(4f11), with a luminescence lifetime of 5.5 ms. After thermal annealing at 900 °C, the lifetime increases to 14.1 ms. Radiation damage was then introduced in the annealed films using 1 MeV He, 3.5 MeV C, 5.5 MeV Si, or 8.5 MeV Ge ions. The lifetime is decreased by irradiation with fluences as low as 1011 ions/cm2 and continues to decrease with fluence until saturation occurs above ≈1014 ions/cm2. The saturation lifetime is ion-mass dependent and ranges from 6.6 to 8.5 ms. The lifetime changes are explained in terms of nonradiative energy transfer processes caused by irradiation-induced defects in the silica. A model for lifetime changes as a function of ion fluence is derived, assuming an inverse relation between the nonradiative lifetime and the defect density. Fits to the data show that the defect generation rate is a sublinear function of the ion fluence. The ion damage effects are governed by the electronic component of the energy loss along the ion trajectories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353201
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  • 6
    Electronic Resource
    Electronic Resource
    The electrical and defect properties of erbium-implanted silicon (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2667-2671 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed study of the electrical and defect properties of ion-implanted erbium in silicon shows that erbium doping introduces donor states. The concentration of erbium related donors as a function of implant dose saturates at 4×1016 cm−3 at a peak implanted Er-ion concentration of (4–7)×1017 cm−3. The defect levels related to erbium in silicon are characterized by deep level transient spectroscopy and identified as E(0.09), E(0.06), E(0.14), E(0.18), E(0.27), E(0.31), E(0.32), and E(0.48). The dependence of the photoluminescence on annealing temperature for float zone and for Czochralski-grown silicon show that oxygen and lattice defects can enhance the luminescence at 1.54 μm from the erbium. Temperature-dependent capacitance-voltage profiling shows donor emission steps when the Fermi level crosses EC − ET = 0.06 eV and EC − ET = 0.16 eV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349381
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  • 7
    Electronic Resource
    Electronic Resource
    Impurity enhancement of the 1.54-μm Er3+ luminescence in silicon (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2672-2678 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of impurity coimplantation in MeV erbium-implanted silicon is studied. A significant increase in the intensity of the 1.54-μm Er3+ emission was observed for different coimplants. This study shows that the Er3+ emission is observed if erbium can form an impurity complex in silicon. The influence of these impurities on the Er3+ photoluminescence spectrum is demonstrated. Furthermore we show the first room-temperature photoluminescence spectrum of erbium in crystalline silicon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349382
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  • 8
    Electronic Resource
    Electronic Resource
    Differential ion damage and its annealing behavior in AlAs/GaAs heterostructures (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1279-1286 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nature of differential ion damage in AlAs-GaAs epitaxial heterostructures is explored using conventional and high-resolution transmission electron microscopy, together with Rutherford backscattering spectrometry. By use of Si+ ion implantation, the rapid buildup of lattice damage in GaAs, and the relative resistance of AlAs to structure breakdown is highlighted. The ion dose levels required for bulk amorphization of the two materials differ by at least two orders of magnitude. The way in which lattice disorder changes near the AlAs/GaAs interface is studied in detail and it is demonstrated that the AlAs layer, which remains crystalline up to high ion doses, promotes in situ annealing of narrow zones of GaAs crystal adjacent to both of its interfaces. These crystalline GaAs zones show substantially enhanced resistance to ion damage accumulation but they contain planar defects and are finally rendered amorphous after extended ion bombardment. During this process, defects propagate into the edges of the AlAs layer which are then progressively amorphized in an apparently heterogeneous (boundary-dependent) manner. In addition, it is shown that GaAs in other regions of the sample is amorphized by a mechanism which at first leaves nanometer-scale blocks of crystal isolated within the newly formed amorphous material, although these blocks are then rapidly broken down by further bombardment. The way in which the implantation-damaged layers restructure during annealing treatment is also described. Up to ∼320 nm of amorphous GaAs beneath the AlAs layer can be regrown as a single crystal by the motion of two opposing growth interfaces during annealing at 800 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347314
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of as-implanted damage on the microstructure of threading dislocations in MeV implanted silicon (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 1221-1225 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dose dependence of as-implanted damage and the density of threading dislocations formed after MeV implants into Si is measured. The role of the damage and amorphization in the evolution of dislocation microstructure is assessed. As-implanted damage is analyzed by Rutherford backscattering spectroscopy and channeling. Defect etching is used to delineate threading dislocations in near-surface regions of annealed (900 °C, 30 min) samples. For a variety of implants with 1.1 μm projected range (600 keV B, 1 MeV P, and 2 MeV As) we observe a sharp onset for formation of threading dislocations with a peak in dislocation density at a dose of about 1×1014 cm−2, this dose depends on the ion mass. With a further increase in dose, the dislocation density decreases. This decrease, however, is drastically different for the different ions: sharp (4–5 orders of magnitude) reduction for P and As implants and slow decline for B implant. The sharp decrease in the density of threading dislocations at higher doses is correlated with the onset of amorphization observed by channeling for P and As implants. Our data for low-temperature implants provide conclusive proof that a reduction in the dislocation density for P and As implants is a result of amorphization. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370874
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  • 10
    Electronic Resource
    Electronic Resource
    Formation of extended defects in silicon by high energy implantation of B and P (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2105-2112 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The extended defects induced in silicon by high energy implantation (1.5 MeV B and 2.6 MeV P) have been investigated by plan-view and cross-sectional transmission electron microscopy studies and defect etching measurements. The threading dislocations were identified to be long dislocation dipoles generated in the region of the ion projected range which grew up to the surface. The formation of threading dislocations is shown to have a strong dependence on the implantation dose and O concentration. After 900 °C annealing, a high density of threading dislocations was formed for B and P implants in a dose range of 5×1013–2×1014 cm−2 and 5×1013–3×1014 cm−2, respectively. The threading dislocation density in B-implanted Czochralski Si substrates was found to be much higher than that in B-implanted epitaxial Si substrates. This difference is attributed to the strong pinning effect of oxygen immobilizing dislocations in Czochralski substrates. Because P impurities are also efficient at pinning dislocation motion in Si, a high density of threading dislocations was observed even in epitaxial Si substrates with P implantation. Two-step annealing with a first step at 700 °C (to precipitate oxygen) and a second step at 900 °C was found to be very effective at eliminating the formation of threading dislocations. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363103
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