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Journal of Applied Physics

Issue 5 • Date Mar 2003

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Displaying Results 1 - 25 of 134
  • Issue Table of Contents

    Page(s): toc1
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    Freely Available from IEEE
  • Vibrational lifetimes of hydrogen in silicon

    Page(s): 2317 - 2336
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    Characterization of defect and impurity reactions, dissociation, and migration in semiconductors requires a detailed understanding of the rates and pathways of vibrational energy flow, of the energy transfer channels, and of the coupling mechanisms between local modes and the phonon bath of the host material. Significant progress in reaching this goal has been accomplished in recent landmark studies exploring the excitation and dynamics of vibrational states associated with hydrogen in silicon. The lifetime of the Si–H stretch mode is found to be extremely dependent on the local solid-state structure, ranging from picoseconds for interstitial-like hydrogen, hundreds of picoseconds for hydrogen–vacancy complexes, to several nanoseconds for hydrogen bonded to Si surfaces—over three orders of magnitude variation. Such large variations in lifetime (transition probability) are extraordinarily rare in solid-state science. The level of theoretical investigation into the vibrational lifetime of the Si–H oscillator is less advanced. This state of affairs is partly because of the difficulties in explicitly treating slow relaxation processes in complex systems, and partly because, as suggested by experiment, a highly anharmonic coupling mechanism is apparently responsible for the (multiphonon) relaxation process. Even more importantly, because of the high frequency of the Si–H stretching motion, a quantum mechanical treatment of the Si–H oscillator is required. A combination of Bloch–Redfield theory and molecular dynamics simulation seems promising in describing the relaxation process of the Si–H vibrational modes. It is the aim of this review article to present a comprehensive overview of the recent accomplishments, current understandings, and future directions in this emerging field of time-resolved vibrational spectroscopy of point defects in solids. © 2003 American Institute of Physics. View full abstract»

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  • Modeling planar leaky optical waveguides

    Page(s): 2337 - 2342
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    A simple theoretical model is proposed for a description of light propagation in ion-implanted leaky waveguides. It permits interpretation of existing published experimental results. A single parameter, the imaginary component of the refractive index, is sufficient to describe losses in the barrier. Simple analytical expressions are obtained for both the lateral resonance condition and the confinement coefficient. For each quasiguided mode, we calculate an optimal barrier thickness which gives the lowest attenuation coefficient. Interestingly, for thick barriers, high-order modes give the best confinement coefficient. Our approach can also describe prism-loaded slab type waveguides. © 2003 American Institute of Physics. View full abstract»

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  • Fabrication of microlenses in Ag-doped glasses by a focused continuous wave laser beam

    Page(s): 2343 - 2348
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    A technique for the fabrication of small (2–10 μm in diameter) microlenses on the surface of glass with embedded silver nanoclusters in a subsurface diffusion layer is demonstrated. The dependence of the microlens size on the exposure time and the laser power of a focused continuous wave (cw) laser beam is discussed. It is shown that the optical transmission of the lenses increases with increasing laser power used for the exposure. The temperature distribution in the glass around the focal spot is calculated taking into account the temperature dependence of heat conductivity, shape of the beam, and decrease of absorption coefficient with depth through the diffusion layer containing Ag clusters. The measured microlens sizes are in good agreement with the calculations. © 2003 American Institute of Physics. View full abstract»

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  • Injection cascade lasers with graded gap barriers

    Page(s): 2349 - 2352
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    We propose cascade structures based on type-II heterostructures with graded barriers separating electron and hole layers. The electron–hole separation is controlled by an external bias due to modification of the barrier shape. This principle can be used for fabrication of a class of devices. In particular, bipolar interband cascade lasers are considered in which an external bias changes the rate of electron–hole radiative recombination by several orders of magnitude. Theoretical calculations predict the feasibility of these lasers. © 2003 American Institute of Physics. View full abstract»

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  • Polarization-dependent intersubband absorption saturation and its effect on polarization selection in vertical cavity surface-emitting lasers

    Page(s): 2353 - 2358
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    A mechanism of nonlinear dichroism of net gain in vertical-cavity surface-emitting lasers based on polarization-dependent saturation of intersubband absorption in p-contact layers is proposed and analyzed. Microscopic perturbative calculations are used to obtain approximate analytical expressions for the magnitude of the effect. It is shown that the proposed mechanism can play a significant part in polarization switching and bistability in vertical-cavity lasers. © 2003 American Institute of Physics. View full abstract»

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  • X-ray induced fluorescence measurement of density distributions in a metal–halide lighting arc

    Page(s): 2359 - 2368
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    The use of x-ray induced fluorescence to measure elemental densities in a metal–halide lighting arc is described. High-energy synchrotron radiation generated on the Sector 1 Insertion Device beam line at the Advanced Photon Source induces K-shell fluorescence in a high-pressure plasma arc. The detected fluorescence is spectrally resolved, so that multiple elemental species are observed simultaneously. Absolute calibration of the measured densities is straightforward and robust. The penetrating nature of high-energy photons allows these measurements to be made in situ, with the arc contained by an optically translucent polycrystalline alumina (Al2O3) arc tube and a glass vacuum jacket. Spatial distributions extending from one end of the arc tube to the other and from the arc core all the way to the wall have been obtained for all the principal elements in the arc. A volume element measuring 1 mm × 1 mm × 1 mm is resolved in the present work, with significantly better spatial resolution possible. Densities as low as 2×1016 cm-3 have been observed. X-ray induced fluorescence is useful for the observation of many important high-pressure plasma lighting chemistries including those containing Hg, Tl, Dy, Tm, Ho, Cs, Sn, I, and Xe. © 2003 American Institute of Physics. View full abstract»

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  • Particle-in-cell/Monte Carlo simulation of a capacitively coupled radio frequency Ar/CF4 discharge: Effect of gas composition

    Page(s): 2369 - 2379
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    A one-dimensional particle-in-cell/Monte Carlo model is developed to study a capacitively coupled radio frequency discharge in a gas mixture of argon and CF4. The simulation takes into account the following charged particles: electrons, two kinds of positive ions (Ar+, CF3+), and two kinds of negative ions (F-, CF3-). The model considers electron–Ar collisions, electron-CF4 collisions, various kinds of collisions of CF3+, F-, CF3-, or Ar+ with Ar or CF4, and positive–negative ion recombination. The probability for the positive–negative ion recombination is determined from a recombination rate constant. The ion–neutral elastic and reactive collisions are simulated by an ion–molecule collision model for endothermic reactions. The typical results of this model are electron and ion densities, fluxes and energy distributions, collision rates, and electric field and potential distributions. The simulation is performed for 0.1/0.9, 0.5/0.5, and 0.9/0.1 ratios of a Ar/CF4 mixture, as well as for pure Ar and pure CF4 discharges at a pressure of 200 mTorr. It is observed that at high CF4 concentration the discharge behaves as a typical electronegative discharge and that CF3+ is the major positive ion. At low CF4 concentration, keeping the other operating parameters the same, the double layer structure and the electron density maxima at the bulk–sheath interface, which are representative for an electronegative discharge, disappear and the Ar+ density exceeds the CF3+ density by more than 1 order of magnitude. The results show that the F- ions are the dominant negatively charged species for all Ar/CF4 ratios investigated. © 2003 American Institute of Physics. View full abstract»

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  • Internal structure and expansion dynamics of laser ablation plumes into ambient gases

    Page(s): 2380 - 2388
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    The effect of ambient gas on the expansion dynamics of the plasma generated by laser ablation of an aluminum target has been investigated using frequency doubled radiation from a Q-switched Nd:YAG laser. The diagnostic tools include fast photography of overall visible plume emission using a 2 ns gated intensified charged coupled device and space and time resolved emission spectroscopy using a 50 cm monochromator/spectrograph and photomultiplier tube. The expansion behavior of the plasma was studied with ambient air pressure ranging from 10-6 to 100 Torr. Free expansion, plume splitting and sharpening, hydrodynamic instability, and stagnation of the plume were observed at different pressure levels. Space and time resolved emission spectroscopic studies showed a twin peak distribution for Al and Al+ species at farther distances illustrating plume splitting at pressures higher than 100 mTorr. Combining imaging together with time resolved emission diagnostics, a triple structure of the plume was observed. The expansion of the plume front was compared with various expansion models and found to be generally in good agreement. © 2003 American Institute of Physics. View full abstract»

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  • Calorimetric measurements of phase transformations in thin films of amorphous Te alloys used for optical data storage

    Page(s): 2389 - 2393
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    Sputtered amorphous Ag0.055 In0.065 Sb0.59 Te0.29, Ge4 Sb1 Te5, and Ge2 Sb2 Te5 thin films were studied by differential scanning calorimetry. The crystallization temperature and the heat of crystallization of the amorphous phases, the melting temperature and the heat of fusion of the crystalline phases, and the heat capacities of crystalline and liquid AgInSbTe were measured. The entropies of fusion are large (≥2R), which suggests a change of bonding type between liquid and crystal. In contrast to amorphous AgInSbTe and Ge4 Sb1 Te5, which upon heating crystallize to a single phase within a small temperature interval, the crystallization of amorphous Ge2 Sb2 Te5 is complicated by a subsequent cubic-to-hexagonal transformation. No thermal evidence of a glass transition was found below the crystallization temperature. The ratio of the glass transition temperature (approximated as the crystallization temperature) to the liquidus temperature is 0.49–0.56, which identifies the materials as marginal glass formers. The heat capacity measurements on AgInSbTe were used to estimate the temperature dependence of the difference in enthalpy, entropy, and Gibbs free energy between the undercooled liquid and the crystal. © 2003 America- n Institute of Physics. View full abstract»

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  • Superelasticity in high-temperature Ni–Mn–Ga alloys

    Page(s): 2394 - 2399
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    The stress–strain behavior of two single crystalline Ni–Mn–Ga alloys with martensitic transformation temperatures above the Curie temperature has been studied during uniaxial compression along the [001] and [110] axes. The superelastic effect associated to the reversible stress-induced martensitic transformation has been obtained in these high-temperature shape memory alloys. The experimental values of the critical stress to induce the martensitic transformation, σc, depend linearly on the test temperature. This dependence is described well by the thermodynamics of the stress-induced martensitic transformation through a Clausius–Clapeyron-type equation. However, the experimental values of slopes c/dT obtained in the two compression directions can only be interpreted well if it is assumed that different martensitic phases are formed for each compression axis. Good agreement with the thermodynamic model exists if tetragonal martensites with c/a≪1 and ≫1 are induced in the [001] and [110] axes, respectively. © 2003 American Institute of Physics. View full abstract»

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  • Interface-layer formation in microcrystalline Si:H growth on ZnO substrates studied by real-time spectroscopic ellipsometry and infrared spectroscopy

    Page(s): 2400 - 2409
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    By applying real-time spectroscopic ellipsometry and infrared attenuated total reflection spectroscopy (ATR), we have characterized interface-layer formation in microcrystalline silicon (μc-Si:H) growth on ZnO substrates in a conventional rf plasma-enhanced chemical vapor deposition. With an increase in the hydrogen dilution ratio (R=[H2]/[SiH4]), we find a significant increase in the interface-layer thickness from 0 (R=0) to 48 Å (R=100). In contrast, no interface-layer formation was observed in μc-Si:H growth on SiO2 substrates. Detailed analyses show that the interface layer formed on ZnO is porous amorphous Si:H with a large amount of SiH2 bonds (16 at. %). During the early stage of interface-layer formation, we observed almost no film deposition and a dramatic increase in free-carrier concentration within the ZnO substrate due to a chemical reduction of ZnO by H-containing plasma. Real-time ATR spectra revealed the predominant formation of SiHnO4-n (n=1-2) species on the ZnO surface prior to interface-layer formation. These SiHnO4-n species are chemically inactive and remain at the μc-Si:H/ZnO interface. Based on these findings, we propose that the SiHnO4-n formation that results from ZnO reduction reaction by H suppresses chemical reactivity on the ZnO surface and induces porous interface-layer formation during the initial deposition proce- ss. © 2003 American Institute of Physics. View full abstract»

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  • Anisotropic photoluminescence from porous silicon layers made under polarized illumination: Origin of contradictory experimental observations

    Page(s): 2410 - 2413
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    A detailed study has been performed on the anisotropic photoluminescence of porous silicon (PSi) layers formed by the electrochemical anodization under polarized illumination. Emphasis is placed on the different effects of the photoelectrochemical dissolution process and the electroless photochemical counterpart on the direction of the anisotropy. Our experimental results indicate that the two dissolution mechanisms induce photoluminescence anisotropy in totally different directions: in photoelectrochemically etched PSi samples, a maximal degree of polarization is observed only when the polarization (Eexc) of the excitation light is parallel to the polarization (Eetch) of the illumination light, while in photochemically etched samples it is observed when Eexc is perpendicular to Eetch. The former and latter results are explained, respectively, by the thinning and disintegration of the Si nanostructures oriented parallel to Eetch during the etching treatments. © 2003 American Institute of Physics. View full abstract»

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  • Ab initio study of elastic properties of Ir and Ir3X compounds

    Page(s): 2414 - 2417
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    Elastic constants and moduli of face-centered cubic Ir and its L12 intermetallic compounds Ir3X (X=Ti, Ta, Nb, Zr, Hf, V) have been determined using ab initio density functional theory calculations within the generalized gradient approximation. With the tetragonal, trigonal, and isotropical lattice distortions, elastic constants C11, C12, C44, and bulk modulus B are derived from the second derivative of the total energy as a function of volume. The calculated Young’s modulus E, shear modulus G, Poisson’s ratio ν, and the ratio RG/B of G over B are then used to examine mechanical properties of Ir and Ir3X compounds. By analyzing RG/B and Cauchy pressure C12–C44, the brittle-ductile behavior of the materials is assessed. Based on the modulus difference ΔG between the γ matrix (Ir) and γ precipitates (Ir3X), the γ strengthening effect in the γ matrix is studied. © 2003 American Institute of Physics. View full abstract»

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  • High-resolution transmission electron microscopy study of metastable silicon phases produced by nanoindentation

    Page(s): 2418 - 2423
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    Plan-view transmission electron microscopy (TEM) and Raman microspectroscopy were used to identify metastable silicon phases in nanoindentation. A mixture of metastable Si-III and Si-XII phases was observed by both selected area diffraction in TEM and Raman analysis. High resolution TEM observations provided detailed structural information about the metastable phases of silicon and the interfaces between different silicon structures. A mechanism of dislocation-induced lattice rotation that leads to a phase transition and distortion-induced amorphization in nanoindentation is proposed. © 2003 American Institute of Physics. View full abstract»

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  • Structure, high temperature transport, and thermal properties of Ba8GaxSi46-x (x=10 and 16) clathrates prepared by the arc melting method

    Page(s): 2424 - 2428
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    Ba8Ga10Si36 and Ba8Ga16Si30 clathrates were prepared by the arc melting method and characterized for their structure, transport, and thermal properties by x-ray diffraction, electron probe microanalysis, electrical resistivity, and thermal conductivity measurements. The Rietveld refinement results gave the total occupancy of Ga/Si equal to 3.49/2.01, 0.99/14.01, and 5.51/17.99 for Ba8Ga10Si36 and 3.99/2.01, 1.99/14.01, and 10.01/13.99 for Ba8Ga16Si30, respectively, for 6c, 16i, and 24k sites. From the refined isotropic thermal displacement parameters, Debye temperature, average velocity of sound, lattice thermal conductivity, and Einstein temperature values were estimated. The calculated lattice thermal conductivity values were in agreement with room temperature experimental values of 1.128 and 1.071 W m-1K-1, respectively, for two clathrates. The temperature variation of (300–850 K) electrical resistivity of Ba8Ga16Si30 showed metallic like behavior, whereas that of Ba8Ga10Si36 showed semiconducting behavior. The semiconducting nature was due to vacancies in the framework sites. High temperature thermal conductivity above Debye temperature was explained with anharmonic approximation. © 2003 American Institute of Physics. View full abstract»

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  • On the lower limiting velocity of a dynamic crack in brittle solids

    Page(s): 2429 - 2434
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    The existence of forbidden velocity gap in dynamic crack propagation in brittle crystals has been proposed previously, based on analytical calculations and numerical simulations. These suggested that the minimal velocity of a dynamically propagating crack is a significant portion of the Rayleigh wave speed. On the other hand, theoretical analysis based on continuum mechanics does not identify any lower limit to the crack velocity. In this work, we studied experimentally the crack velocity in glass and single-crystal silicon, in a geometry that constrains the crack profile to a nearly quarter elliptical shape, such that at a certain part of the crack it is forced to move appreciably slowly. Direct measurements show that the crack velocity along this profile decreases to less than 1% of the Rayleigh wave speed, both at room temperature and at 77 K, which is notably below the expected velocity gap. © 2003 American Institute of Physics. View full abstract»

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  • Elastic and piezoelectric fields in a substrate AlN due to a buried quantum dot

    Page(s): 2435 - 2439
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    Using the Green’s function solution in an anisotropic and linearly piezoelectric half space developed recently by the authors, this article studies the elastic and piezoelectric fields in substrate AlN due to a buried quantum dot (QD). Two different growth orientations are considered: One is the AlN (0001) growing along the (0001) axis, and the other is the AlN (1000) growing along the polar direction [i.e., a direction normal to (0001) axis]. For an InN QD, modeled as a concentrated source, with a volume va=4πR3/3 where R=3 nm, and the typical values of misfit strain, at a depth h=10 nm below the surface, the following features have been observed: (1): on the surface of substrate AlN (0001), the hydrostatic strain, piezoelectric potential, and vertical and horizontal electric fields are rotationally symmetric with respect to the z axis. However, these quantities are not rotationally symmetric on the surface of substrate AlN (1000); (2): a hydrostatic strain as large as 0.01 on the surface of the AlN (1000) and as large as 0.008 on the surface of AlN (0001) can be reached, both of which are larger than that on the surface of the substrate GaAs due to a QD with the same volume at the same depth; (3): the piezoelectric potential on the surface of substrate AlN (0001) is much larger than that on the surface of AlN (1000), i.e., 0.8 versus 0.3 V; and (4): large horizontal and vertical electric fields, in the order of 108V/m, can be induced on the surface of AlN, about two orders of magnitude larger than that on the surface of the substrate GaAs due to a QD with the same volume at the same depth. © 2003 American Institute of Physics. View full abstract»

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  • In-plane photovoltage and photoluminescence studies in sequentially grown GaInNAs and GaInAs quantum wells

    Page(s): 2440 - 2448
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    We have investigated in-plane photovoltage (IPV) and photoluminescence (PL) in sequentially grown Ga0.8In0.2As/GaAs and Ga0.8In0.2N0.015As0.985/GaAs quantum wells. Temperature, excitation intensity, spectral and time dependent study of the IPV, arising from Fermi level fluctuations along the layers of the double quantum well structure, gives valuable information about the nonradiative centers and hence about the optical quality of the GaInNAs quantum well. It also provides information about the radiative transition energies in all the layers. In order to obtain either the trap activation energies and the detrapping rates of photogenerated carriers in the GaInNAs the IPV results are analyzed in terms of a theoretical model based on random doping fluctuations in nominally undoped multilayer structures. The PL results are analyzed in terms of the band anticrossing model to obtain the electron effective mass from the coupling parameter CNM. © 2003 American Institute of Physics. View full abstract»

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  • Defect evolution of low energy, amorphizing germanium implants in silicon

    Page(s): 2449 - 2452
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    The defect evolution upon annealing of low energy, amorphizing germanium implants into silicon was studied using plan-view transmission electron microscopy. Implants with energies of 5–30 keV at an amorphizing dose of 1×1015 Ge+ cm-2 were annealed at 750 °C from 10 s to 360 min. For the implant energies of 10 and 30 keV, the defects form clusters which evolve to {311} defects that subsequently dissolve or form stable dislocation loops. However, as implant energy drops to 5 keV, the interstitials evolve from clusters to small, unstable loops which dissolve within a small time window and do not form {311}’s. To determine the effect of the free surface as an interstitial recombination sink for 5 keV implants, the amorphous layer of a 10 keV implant was lapped to less than the thickness of a 5 keV amorphous layer and then annealed. We found that the defect dissolution observed for the 5 keV implant energy was dependent on the implant energy and not the proximity of the end-of-range damage to the surface. The activation energy of the observed rapid defect dissolution at 5 keV was calculated to be 1.0±0.1 eV. © 2003 American Institute of Physics. View full abstract»

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  • Viscoelastic stress relaxation in film/substrate systems—Kelvin model

    Page(s): 2453 - 2457
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    Although the Maxwell model was widely applied to analyze viscoelastic behavior of film/substrate systems, Rafferty etal [Appl. Phys. Lett. 54, 151 (1989)] found that the structural relaxation of silicon oxide films on silicon wafers during thermal annealing could be explained by the Kelvin model but not the Maxwell model. This result motivated us to investigate the relaxation of residual stresses due to viscoelastic deformation in a film/substrate system using the Kelvin model. The system can be a viscoelastic film on an elastic substrate or an elastic film on a viscoelastic substrate. The viscoelastic solutions of both cases can be obtained from the elastic solution using the Laplace transform. The stress relaxation rate increases with decreasing film-to-substrate thickness ratio for a viscoelastic film deposited on an elastic substrate. However, it shows the opposite trend for an elastic film deposited on a viscoelastic substrate. The present results are compared with those obtained from the Maxwell model. © 2003 American Institute of Physics. View full abstract»

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  • Size effects of optical and magneto-optical properties of epitaxial CrPt3 films

    Page(s): 2458 - 2463
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    The magneto-optical polar Kerr effect and the optical functions of epitaxial films of CrPt3 have been studied as a function of film thickness. For this purpose, a wedge-shaped film was grown with film thickness ranging from 0 to 100 nm. A Kerr rotation of about 0.25° and -0.5° has been found in the near-ultraviolet and near-infrared spectral range, respectively, for the thicker films, decreasing rapidly with decreasing film thickness. In contrast, the shapes of the Kerr rotation and ellipticity spectra remain nearly unchanged. The optical functions are found to be strongly affected by the film morphology, which was studied by reflection high-energy electron diffraction and atomic force microscopy. The results are in good agreement with effective-medium calculations. © 2003 American Institute of Physics. View full abstract»

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  • Interface properties and reliability of ultrathin oxynitride films grown on strained Si1-xGex substrates

    Page(s): 2464 - 2471
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    The role of nitrogen in improving the interface properties and the reliability of oxynitride/SiGe interfaces and the dielectric properties of oxynitride films has been studied using constraint theory. Ultrathin (≪3 nm) oxynitride films were grown using N2O followed by N2 annealing on strained Si0.82Ge0.18 layers. Silicon dioxide films grown on strained Si0.82Ge0.18 layers were also nitrided in N2O by rapid thermal processing. The nitrogen distribution in the oxynitride films was investigated by time-of-flight secondary ion mass spectrometry. The interface state density, charge trapping properties, and interface state generation with constant current and voltage stressing were studied. It is observed that dielectric films grown in N2O ambient and subsequently annealed in N2 have excellent electrical properties. A low stress-induced leakage current and a high time dependent dielectric breakdown are also observed in these films. Improvements in the electrical properties are shown to be due to the creation of a large number of strong Si–N bonds both in bulk and in the SiON–Si1-xGex interface region of the dielectric. © 2003 American Institute of Physics. View full abstract»

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  • Continuous model for the shear modulus as a function of pressure and temperature up to the melting point: Analysis and ultrasonic validation

    Page(s): 2472 - 2480
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    The aim of the present study is to propose a predictive model for the shear modulus versus pressure and temperature G(P,T) to complete the principal known elasto-plastic models implemented in hydrodynamic computer codes. The relevance of the proposed G(P,T) model is discussed in detail. The generic approach is to model G(T) by considering Lindemann theory at the melting point. This article focuses on analysis of the mechanical elastic behavior of a solid to confirm that the melting point and the shear component attenuation are closely connected. The drastic fall of G(T) at the melting point is discussed and compared to experimental data mainly derived from ultrasonics. The original part of this work is the experimental work concentrating on direct measurement of the shear wave velocity. The five materials of interest have melting points ranging from that of tin (505 K) to that of tantalum (3269 K). The corresponding Lindemann constant is determined, leading to an average value of 0.103 for cubic crystalline symmetry (Ta, Cu, Au, and Al) and 0.060 for tetragonal crystalline symmetry (Sn). We propose a relationship between G(P,T) and the melting temperature. © 2003 American Institute of Physics. View full abstract»

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  • Defects in ZnO thin films grown on ScAlMgO4 substrates probed by a monoenergetic positron beam

    Page(s): 2481 - 2485
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    Zinc oxide (ZnO) thin films grown on ScAlMgO4 substrates were characterized by means of positron annihilation. We measured Doppler broadening spectra of annihilation radiation and photoluminescence spectra for the ZnO films deposited by laser molecular-beam epitaxy and single-crystal ZnO. Although the lifetime of positrons in single-crystal ZnO was close to the lifetime of positrons annihilated from the free state, the diffusion length of positrons was shorter than that for typical defect-free materials. We attribute this to the scattering of positrons by native defects. For the ZnO films, we observed a correlation between the defects and the lifetime of bound exciton emissions τEx; the main defect species detected by positron annihilation was Zn vacancies or other related defects. Isochronal annealing at 750–850 °C was found to introduce additional vacancy-type defects into the film, although the value of τEx was scarcely changed by the annealing. © 2003 American Institute of Physics. View full abstract»

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Aims & Scope

Journal of Applied Physics is the American Institute of Physics' (AIP) archival journal for significant new results in applied physics

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Editor
P. James Viccaro
Argonne National Laboratory