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  • 1
    Electronic Resource
    Electronic Resource
    Temperature measurements of polyimide during KrF excimer laser ablation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4344-4350 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temperature at the interface between a thin polyimide film and a quartz substrate was monitored as a function of time during KrF (248 nm) laser-induced heating and ablation using thin film NiSi thermistors. These experimental temperature measurements were coupled with heat flow simulations to obtain time-resolved temperature profiles in the polyimide. Thermal properties of the polyimide were estimated by requiring that the simulations reproduce experimental temperature profiles. The peak surface temperature of the polyimide at the onset of ablation was subsequently estimated from these constrained simulations and a value of 1660±100 K was obtained for the observed ablation threshold fluence of 36 mJ/cm2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352198
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of the elastic constants of anisotropic materials using laser-generated ultrasonic signals (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 150-157 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper presents the solution of the materials characterization problem in which the elastic constants of an anisotropic material are determined from ultrasonic wavespeed measurements made in nonprincipal directions of a specimen. The ultrasonic waves were generated via the point-source/point-receiver technique using a pulsed laser as a source and a miniature, point-like transducer as a receiver. Data were acquired during a scan of the source along one of the principal acoustic axes of symmetry of the material. In each waveform the arrivals of the quasi-longitudinal and the two quasi-shear bulk modes were measured and the elastic constants of the material were then recovered using an optimization algorithm. Experimental results are presented for a transversely isotropic, unidirectional fiberglass/polyester and a single crystal specimen of silicon. It was found that the nonlinear fit between the measured and the recovered longitudinal slowness values is excellent. Some discrepancies are observed in the data for the two shear modes. These are shown to be related to the complexity of the detected signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350303
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  • 3
    Electronic Resource
    Electronic Resource
    Bulk diffusion measurements to study the effectiveness of barrier layers: I. Mathematical treatment (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 3799-3809 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The exchange of a tracer material, e.g., a radioactive isotope, between two samples forming a diffusion couple depends on the rate of the diffusion of the tracer in each of the two samples and also on the rate of the transfer of the tracer across the interface between these samples which may or may not contain a barrier layer with a different chemical composition and/or structure. Diffusion couples with three different initial tracer distributions are considered. In order to extract from experimental data values for tracer diffusion coefficients and for the rate constant for the tracer transport across the interface, a detailed analysis of the required mathematics is given. This analysis is of interest as well for obtaining true values for bulk diffusivities and also to characterize quantitatively the resistance of interfaces (=barriers) to the exchange of certain species. Some examples of experimental results are presented and briefly discussed. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1402150
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  • 4
    Electronic Resource
    Electronic Resource
    Time-resolved temperature measurements during pulsed laser irradiation using thin film metal thermometers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2615-2623 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article, we describe a technique using NiSi and Pt thin film metal thermometers to provide accurate temperature information on a nanosecond time scale during pulsed laser processing of materials. A surface layer of interest is deposited onto the thermometer layer, and temperatures are determined from temperature dependent changes in the metal film's resistance. Details concerning the design and fabrication of the device structure and experimental considerations in making nanosecond resolved resistance measurements are discussed. Simple analytical estimates are presented to extract quantities such as incident laser energy stored in the sample. Finally, transient temperature data in the thermometer film, in combination with heat flow calculations, allow temperature determination as a function of time and depth into the sample and, additionally, can provide information about material properties of the surface layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143879
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  • 5
    Electronic Resource
    Electronic Resource
    Germanium partitioning in silicon during rapid solidification (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1575-1582 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pulsed laser melting experiments were performed on GexSi1−x alloys (x≤0.10) with regrowth velocities ranging from 0.25 to 3.9 m/s. Analysis of post-solidification Ge concentration profiles, along with time-resolved melt depth measurements, allowed determination of the liquid-phase diffusivity Dl for Ge in Si and the dependence of the Ge partition coefficient k on interface velocity v. A Dl of 2.5×10−4 cm2/s was measured. The k vs v data were analyzed using various models for partitioning, including both the dilute and nondilute Continuous Growth Models (CGM). Extrapolating to zero velocity using the partitioning models, an equilibrium partition coefficient of approximately 0.45 was obtained. Best fitting of partitioning data to the nondilute CGM yields a diffusive speed of 2.5 m/s. These measurements quantify previous indications of partitioning observed in other studies of pulsed laser processed GexSi1−x alloys. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360251
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  • 6
    Electronic Resource
    Electronic Resource
    Equilibrium concentrations of defects in pure and B-doped silicon (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8998-9011 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Empirical tight-binding (ETB) calculations have been used in extensive searches for new point defect structures in pure silicon as well as silicon doped with boron. In general, these searches, which use a steepest-descents energy minimization from random starting structures, have produced the same set of simple defects in pure silicon (tetrahedral interstitials, split interstitials, and simple vacancies) which have been widely studied. However, a variety of boron interstitials, and several new di-interstitials (with and without boron) have been discovered. Similarities between these defects and defects found in ab initio and classical studies are discussed, as well as the accuracy of the theoretical results in general. A Stillinger–Weber (SW) model for Si–B interactions has been developed in order to obtain vibrational entropies for simple point defects. Using the SW potential, concentration prefactors have been obtained, and traditional Arrhenius plots for concentration have been produced. The theoretical equilibrium concentrations of self-interstitials are consistent with results obtained from Pt and Au In-diffusion experiments, and contrast with oxidation-enhanced diffusion/oxidation-retarded diffusion (OED/ORD)-derived results. The theoretical results for point defect concentrations and binding energies are used to examine the assumptions of several diffusion models. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362632
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  • 7
    Electronic Resource
    Electronic Resource
    Demonstration of laser-assisted epitaxial deposition of GexSi1−x alloys on single-crystal Si (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1768-1770 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report initial results of a novel technique for epitaxial growth of GexSi1−x alloys on single-crystal Si. During electron beam deposition of amorphous GexSi1−x, an incident XeCl excimer laser, operating at 308 nm with a 30 ns pulse duration, melts and crystallizes the amorphous layer in situ after each ≈5 nm of deposition. This laser-induced melt extends approximately 20 nm and provides epitaxy from the underlying substrate (or previous layers) at each stage of deposition. This melt/solidification process can be repeated continuously until the final desired alloy thickness is achieved. For layers up to 260 nm with Ge concentrations of 1.5–3 at. %, MeV ion channeling and cross-sectional transmission electron microscopy confirm epitaxial growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105085
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  • 8
    Electronic Resource
    Electronic Resource
    Thermal nitridation enhanced diffusion of Sb and Si(100) doping superlattices (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1273-1275 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Depth dependent nitridation enhanced diffusion (NED) of Sb was investigated by annealing Si(100) doping superlattice (DSL) structures in NH3 at 810–910 °C for 15–180 min. These multilayered DSLs consisted of six 10 nm wide Sb doping spikes spaced 100 nm apart. Antimony NED, attributed to vacancy injection, indicated vacancy supersaturation values of 3–5. From the spatial decay of Sb NED, lower bounds for vacancy diffusivities of (7.9±1.4)±10−14, (1.2±0.2)×10−12, and 2.1×10−11 cm2/s were obtained at 810, 860, and 910 °C, respectively. Evidence of trap limited vacancy diffusivity was observed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117389
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and magnetic properties of Ni–Al2O3 thin films (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 1189-1195 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ni–Al2O3 nanocomposite thin films have been produced on sapphire, silicon, and silica substrates by a combination of sol-gel processing and partial reduction reactions. Transmission electron microscopy shows Ni particles, ∼20 nm in diameter, embedded in slightly larger diameter alumina grains. X-ray diffraction lattice parameter measurements suggest that the Ni is in a state of nonhydrostatic strain. Magneto-optical Kerr effect measurements indicate that the Ni particles in the films on the silicon and silica substrates support perpendicular magnetization. The saturation Kerr rotation increases linearly with film thickness to values above pure Ni and independent of reflectivity, indicating that the material is behaving as a Faraday rotator. The enhanced magnetic properties of the composite films are related to the nonhydrostatic strain developed in the Ni particles during fabrication. It is argued that the strains originate from the coefficient of thermal expansion mismatch between the film and substrate, and likely the volume shrinkage associated with the reduction reaction. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365887
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  • 10
    Electronic Resource
    Electronic Resource
    Quench rate enhancement in pulsed laser melting of Si by processing under water (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 535-537 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thermal quench rate during pulsed laser heating of Si can be enhanced by immersing the sample in a liquid (e.g., water) during irradiation. The liquid in contact with the irradiated surface acts as an additional heat sink increasing the thermal quench rate. The heat transfer processes and phase transformations were studied in real time using transient optical reflectance and electrical conductance techniques. Measurements of the melting and solidification dynamics of the Si reveal that the quench rate may be enhanced by 30% for deep melts. The measurements also indicate that a steam or superheated water phase is formed near the Si surface during the laser pulse. The observed phenomena are analyzed in terms of standard heat flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99408
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