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15 Nov 1999

Volume 86, Issue 10, pp. 5331-5914

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Design considerations for x-ray free electron lasers

G. Dattoli and P. L. Ottaviani

J. Appl. Phys. 86, 5331 (1999); http://dx.doi.org/10.1063/1.371528 (6 pages) | Cited 4 times

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We develop design considerations on the possibility of generating free electron laser radiation in the x-ray region of the spectrum (50–60 Å), by exploiting a frequency multiplier scheme. We propose a free electron device consisting of a relatively low energy linac (750 MeV) and three sections: an oscillator at 150 nm, an amplifier tuned at the fifth harmonic of the first and a second amplifier operating at a subharmonic of the second amplifier. The seedless amplification is ensured by the e-beam bunching, induced in the oscillator and in the second section, which plays the role of amplifier and modulator. We also explore the possibility of overcoming the problems associated with the bunching efficiency dilution, due to intracavity saturation of the first section, by discussing the regeneration of the bunching by the use of a cavity dumping, realized with a suitable e-beam energy or cavity detuning modulation. © 1999 American Institute of Physics.
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41.60.Cr Free-electron lasers
42.55.Vc X- and γ-ray lasers
42.60.By Design of specific laser systems
42.60.Fc Modulation, tuning, and mode locking
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Nv Optical frequency converters
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Ultrahigh-resolution, frequency-resolved resonance fluorescence imaging with a monoisotopic mercury atom cell

A. A. Podshivalov, M. R. Shepard, O. I. Matveev, B. W. Smith, and J. D. Winefordner

J. Appl. Phys. 86, 5337 (1999); http://dx.doi.org/10.1063/1.371529 (5 pages) | Cited 4 times

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A novel method of ultrahigh-resolution, frequency-resolved imaging using atomic vapor cells is proposed. The method is based on the accurate measurement of the fluorescence signal intensity distribution along the absorption path length when the signal frequency is tuned to a wing of the atomic absorption line. Two-step resonance fluorescence of 202Hg vapor was used for one-dimensional imaging of the Hg resonance radiation at 253.7 nm. An imaging signal with a frequency difference of 500 MHz could be easily distinguished visually and even a frequency difference of 80 MHz could be detected after appropriate processing of the fluorescence imaging signal. Several other novel methods of one- and two-dimensional multifrequency imaging are discussed. © 1999 American Institute of Physics.
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07.60.Rd Visible and ultraviolet spectrometers

Anomalous transmission through near unit index contrast dielectric photonic crystals

P. Loschialpo, D. W. Forester, and J. Schelleng

J. Appl. Phys. 86, 5342 (1999); http://dx.doi.org/10.1063/1.371530 (6 pages) | Cited 5 times

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We present calculations that reveal a limitation for devices that demand photonic crystals with very narrow band gaps. The opaque regions of the transmission spectra through finite length crystals may be substantially broader than the band gap of the corresponding infinite crystals. This is a consequence of the crystals’ near unit dielectric index contrast. The opaque spectral width decreases gradually with increasing thickness. Many hundreds of layers may be needed to obtain a transmission null which approaches the width of the band gap for the infinite crystal. The analysis is done for two configurations of interest for optical applications due to their relative ease of manufacturer. The first is a two-dimensional triangular array of dielectric rods for which finite difference time domain simulations are done to determine the transmission spectra. The second is a one-dimensional dielectric stack for which transmission is analytically calculated. © 1999 American Institute of Physics.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.50.-p Quantum optics
42.70.Qs Photonic bandgap materials

Surface nonlocality effects on an optically active waveguide

D. F. Nelson

J. Appl. Phys. 86, 5348 (1999); http://dx.doi.org/10.1063/1.371531 (8 pages) | Cited 4 times

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A new wave-vector-space method capable of finding electromagnetic wave propagation in bounded nonlocal media without using boundary conditions is used to find the modes of an optically active planar dielectric waveguide. Optical activity involves first-order wave-vector dispersion (nonlocality). The method finds how the altered nonlocal interaction close to the surfaces affects the waveguide modes. It is found that first-order effects of the surface layer nonlocality enter both the dispersion relation and the field profiles. The waveguide geometry is also used as an impetus to generalize several aspects of the wave-vector-space method. © 1999 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
42.65.Wi Nonlinear waveguides
42.25.Ja Polarization
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Neutral depletion and transport mechanisms in large-area high density plasma sources

G. R. Tynan

J. Appl. Phys. 86, 5356 (1999); http://dx.doi.org/10.1063/1.371532 (9 pages) | Cited 20 times

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Plasma uniformity has been recognized as a significant parameter in large-sized high density plasma processing tools, but neutral uniformity issues have received less attention. In this article we show experimental and modeling results which indicate that significant neutral uniformity variations can occur in high density plasma processing tools. The experiments are carried out in both inductively coupled plasma and helicon plasma sources. A movable static pressure gauge is used to obtain the static radial neutral pressure distribution both with and without a discharge present. Without a wafer present in the reactor, significant (∼20%–40%) reductions in neutral pressure are observed in these sources during steady-state plasma operations. This spatially averaged neutral depletion is accompanied by hollow neutral pressure profiles. The degree of on-axis neutral depletion depends upon both plasma density and neutral fill pressure. We show that the “plasma pumping” effect, wherein electron impact ionization of neutral particles is followed by their rapid removal from the plasma by the pre-sheath electric field, can reproduce the experimental results. This effect has the potential to result in large (∼50%) neutral density variation across 300 mm wafers in high density plasma sources. © 1999 American Institute of Physics.
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52.50.Dg Plasma sources
52.25.Kn Thermodynamics of plasmas
52.25.Fi Transport properties
52.20.-j Elementary processes in plasmas

A discharge lamp based on MgH radiation

Shin Ukegawa and Alan Gallagher

J. Appl. Phys. 86, 5365 (1999); http://dx.doi.org/10.1063/1.371533 (7 pages) | Cited 3 times

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We report the efficacy and spectrum of an inductively-coupled, radio-frequency discharge in mixtures of magnesium (Mg), hydrogen (H2), and argon vapor. The predominantly green emission is dominated by the A–X band of MgH, plus some Mg lines. The discharge operates in a frit-sealed, ∼600 °C alumina cell with a sapphire window, at pressures of 200–600 Pa. The plasma impedance is established from the impedance of the matching network parameters, and the electron temperature is determined from line intensity ratios. Assuming isotropic emission, a maximum energy efficiency (η) of ∼ 10% (efficacy ∼ 90 lm per watt) is achieved, where η is the ratio of visible emission to power delivered to the matching network. © 1999 American Institute of Physics.
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52.80.Pi High-frequency and RF discharges
42.72.Bj Visible and ultraviolet sources
84.47.+w Vacuum tubes
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Copper complexes in silicon

Minoru Nakamura and Hitoshi Iwasaki

J. Appl. Phys. 86, 5372 (1999); http://dx.doi.org/10.1063/1.371613 (4 pages) | Cited 13 times

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In order to investigate the exchange between copper complexes (Cu centers) in silicon crystal, the change of the photoluminescence (PL) intensity of the Cu center (Cu PL center; no-phonon peak: 1.014 eV) with annealing time was measured for p-type float-zone grown silicon crystals diffused with various concentrations of Cu at 700 °C followed by rapid cooling to room temperature. It was essential to assume the presence of at least one preceding species (precursor) of the Cu PL center to explain the annealing behavior of the PL intensity. Almost the same quantity of the precursor as the Cu PL center was estimated to remain in the as-cooled crystal. The formation energy of the Cu PL center was 0.57±0.05 eV, and dissociation energy was 0.63±0.05 eV. A positive correlation between the precursor of the Cu PL center and the deep level transient spectroscopy center located at Ec−0.15 eV was suggested. © 1999 American Institute of Physics.
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71.55.Cn Elemental semiconductors
78.55.Ap Elemental semiconductors
61.72.Cc Kinetics of defect formation and annealing

Thermal equilibrium concentrations of the amphoteric dopant Si and the associated carrier concentrations in GaAs

Chang-Ho Chen, Ulrich M. Gösele, and Teh Y. Tan

J. Appl. Phys. 86, 5376 (1999); http://dx.doi.org/10.1063/1.371534 (9 pages) | Cited 1 time

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Expressions of the thermal equilibrium concentrations of Si in GaAs have been obtained in terms of fundamental constants of the involved materials. Silicon is an amphoteric dopant in GaAs, with four species: a neutral and an ionized shallow donor species occupying Ga sublattice sites, and a neutral and an ionized shallow acceptor species occupying As sublattice sites. The concentration of an ionized Si species is expressed by the concentration of the appropriate neutral species and the GaAs crystal Fermi level or the carrier concentration and the band gap energy level positions. The thermal equilibrium concentrations of the two neutral species are expressed by the relevant Gibbs free energies of formation and the As4 vapor phase pressure in the ambient. Using these equations, the long observed relations between the carrier and Si concentrations in different experiments involving both n- and p-type Si doping produced GaAs are quantitatively explained. A difference of ∼1.55 eV in the effective formation enthalpy between the neutral Si atoms occupying the As and Ga sublattice sites has been identified. Moreover, at high temperatures, the GaAs intrinsic Fermi level energy Ei appears to be higher than the midgap energy Eg/2 by ∼20–80 meV. © 1999 American Institute of Physics.
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61.72.S- Impurities in crystals
71.55.Eq III-V semiconductors
65.20.-w Thermal properties of liquids
65.40.gd Entropy

Defects in p+-gate metal–oxide–semiconductor structures probed by monoenergetic positron beams

Akira Uedono, Masako Hiketa, Shoichiro Tanigawa, Tomohisa Kitano, Taishi Kubota, Mariko Makabe, Ryoichi Suzuki, Toshiyuki Ohdaira, and Tomohisa Mikado

J. Appl. Phys. 86, 5385 (1999); http://dx.doi.org/10.1063/1.371535 (7 pages) | Cited 1 time

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Defects in p+-gate metal–oxide–semiconductor structures were probed using monoenergetic positron beams. Doppler broadening profiles of the annihilation radiation and lifetime spectra of positrons were measured for BF2+- or B+-implanted polycrystalline-Si(300 nm)/SiO2(4 nm)/Si specimens. The line-shape parameter, S, corresponding to the annihilation of positrons near SiO2 films was decreased by annealing treatments performed after ion implantation. This fact was attributed to the trapping of positrons by vacancy-oxygen complexes introduced by the boron diffusion in the SiO2 film. The introduction of such complexes was enhanced by incorporation of fluorine, but suppressed by doping of phosphorus into polycrystalline films. © 1999 American Institute of Physics.
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78.70.Bj Positron annihilation
61.72.uf Ge and Si
61.80.Jh Ion radiation effects
61.72.Cc Kinetics of defect formation and annealing
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
61.72.J- Point defects and defect clusters

Oxygen-related defects in O+-implanted 6H–SiC studied by a monoenergetic positron beam

Akira Uedono, Shoichiro Tanigawa, Takeshi Ohshima, Hisayoshi Itoh, Yasushi Aoki, Masahito Yoshikawa, and Isamu Nashiyama

J. Appl. Phys. 86, 5392 (1999); http://dx.doi.org/10.1063/1.371536 (7 pages) | Cited 7 times

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Vacancy-type defects and their annealing properties for O+- or N2+-implanted 6H–SiC were studied using a monoenergetic positron beam. For ion-implanted specimens with a dose of 1×1013 cm2, the mean size of open volume of defects was estimated to be close to the size of divacancies. Annealing processes of the damage were identified to be agglomerations of vacancy-type defects due to migrations of carbon vacancies (100–400 °C), silicon vacancies (400–800 °C), and vacancy complexes such as divacancies (800–1000 °C), and the annealing out of the open spaces adjacent to extended defects (1000–1400 °C). From a comparison between the annealing behaviors of defects for the O+-and the N2+-implanted specimens, the migration and the agglomeration of vacancy-type defects were found to be suppressed in the O+-implanted specimen. This fact was attributed to the formation of complexes between vacancy-type defects and oxygen. For ion-implanted specimens with a dose of 1×1015 cm2, annealing behaviors of amorphous regions were also studied. © 1999 American Institute of Physics.
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61.72.Yx Interaction between different crystal defects; gettering effect
61.72.Cc Kinetics of defect formation and annealing
61.72.Nn Stacking faults and other planar or extended defects
61.72.up Other materials
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
78.70.Bj Positron annihilation

Defects in Ge+-preamorphized silicon

Peng-Shiu Chen, T. E. Hsieh, Yih-Chyang Hwang, and Chih-Hsun Chu

J. Appl. Phys. 86, 5399 (1999); http://dx.doi.org/10.1063/1.371537 (8 pages)

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This work studied the morphology and annealing behaviors of extended defects in Si subjected to various Ge+ preamorphization and BF2+ implantation conditions. The extended defects formed were near the specimen surface when Ge+ implantation energy and dose amount were low. During subsequent annealing, the end-of-range (EOR) loops were enlarged and then moved out of the specimen. High energy/low dose Ge+ implantation generated a damaged layer which initially transformed into a wide zone containing dislocation loops and rodlike defects in the annealed specimen. As the annealing proceeded, the width of defective zone gradually shrunk so that most of the extended defects could be annihilated by defect rejection/recombination process. In addition to the category II defects found in previous investigations, hairpin dislocations emerged in high energy/high dose Ge+-implanted specimens. In this specimen, rodlike defects and hairpin dislocations could be removed by annealing, while the EOR loops became relatively inert so that their removal would require high temperatures and/or long annealing times. Microwave plasma surface treatment was also carried out to form a nitride layer on specimen surface. Experimental results indicate that in addition to effectively reducing the size of EOR loops, surface nitridation might serve as a vacancy source injecting vacancies into Si to annihilate the interstitials bounded by dislocation loops. Reduction in the defect size was pronounced when bias voltage was added to the plasma process. However, radiation damage might occur with too high of a bias voltage. © 1999 American Institute of Physics.
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61.72.uf Ge and Si
81.05.Cy Elemental semiconductors
81.05.Gc Amorphous semiconductors
61.80.Jh Ion radiation effects
61.72.Nn Stacking faults and other planar or extended defects
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Lk Linear defects: dislocations, disclinations
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.65.-b Surface treatments
61.72.Yx Interaction between different crystal defects; gettering effect
61.72.J- Point defects and defect clusters

Kinetics of Ag/Al bilayer self-encapsulation

Y. Wang, T. L. Alford, and J. W. Mayer

J. Appl. Phys. 86, 5407 (1999); http://dx.doi.org/10.1063/1.371538 (6 pages) | Cited 4 times

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The self-encapsulation kinetics of Ag/Al bilayers were studied both experimentally and theoretically as part of the effort to introduce Ag as an alternative metallization scheme for future ultra-large-scale-integrated technologies. Theoretical modeling was based on an analytical solution of a modified diffusion equation, which incorporated the diffusion of Al atoms through the Ag layers during the Ag/Al bilayer encapsulation progress. The amount of segregated Al atoms was monitored by both Rutherford backscattering spectrometry and film resistivity measurements, and correlated well with the theoretical predictions. These findings showed that the kinetics of the self-encapsulation could be significantly affected by both (i) the chemical affinity between Al and Ag atoms, and (ii) the interfacial energy between the metal layer (Ag) and the newly formed AlxOyNz diffusion barriers. Higher anneal temperatures were shown to accelerate the encapsulation process, and hence, achieved a lower resistivity in the underneath Ag layer. This model, in addition, confirmed the self-passivating characteristics of AlxOyNz diffusion barriers formed by Ag/Al bilayers annealed between 500 and 725 °C. © 1999 American Institute of Physics.
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85.40.Ls Metallization, contacts, interconnects; device isolation
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis

Twist elastic constants of liquid crystals using in-plane electrode structure

K. Ikeda, H. Okada, H. Onnagawa, and S. Sugimori

J. Appl. Phys. 86, 5413 (1999); http://dx.doi.org/10.1063/1.371539 (4 pages) | Cited 4 times

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A new technique for measuring the twist elastic constant (K22) using an in-plane electrode structure was investigated. The variation in the temperature dependence of K22 with respect to the molecular structure of fluorinated phenylbicyclohexane (PBC) compounds was investigated. The experimental cell has in-plane electrodes between which the liquid crystal molecules are aligned to an offset angle of azimuthal direction. Using K22 as a fitting parameter, the transmittance–voltage curves for the calculated results are fitted to those for the experimental results. In addition, the investigation of the temperature dependence of K22 revealed that the PBC compound having a para-cyano substituent at the benzene ring exhibits larger splay elastic constant and larger temperature dependence. Finally, molecular association is discussed based on the experimental results. © 1999 American Institute of Physics.
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62.10.+s Mechanical properties of liquids
61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
78.20.Jq Electro-optical effects

Simulation of material properties of amorphous carbon nitride with different nitrogen concentrations

Y. F. Lu, Z. F. He, and Z. M. Ren

J. Appl. Phys. 86, 5417 (1999); http://dx.doi.org/10.1063/1.371540 (5 pages) | Cited 7 times

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A theoretical model is proposed to simulate the structures of amorphous carbon nitride. An understanding of amorphous carbon nitride structures and properties is helpful for the synthesis and applications of this novel material. The influence of the nitrogen concentration on the cohesive energy, bulk modulus, and vibration density spectra was studied. An expression for the total cohesive energy of an atom group was established. The material structure can be simulated by minimizing the total energy of the atoms in the group. From the simulated structure of the material, many properties can be predicted. The results show that either high or low nitrogen concentrations in the carbon nitride led to a high bulk modulus. The vibrational spectra of carbon and nitrogen atoms depend on the nitrogen concentration. This theoretical model may help to identify an appropriate process to grow hard films with expected properties. © 1999 American Institute of Physics.
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61.43.Er Other amorphous solids
62.20.D- Elasticity
63.50.-x Vibrational states in disordered systems

Low-temperature defect chemistry of oxides. I. General aspects and numerical calculations

K. Sasaki and J. Maier

J. Appl. Phys. 86, 5422 (1999); http://dx.doi.org/10.1063/1.371541 (12 pages) | Cited 30 times

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Using oxides as examples, the defect chemistry is systematically analyzed for a low-temperature regime, at which the oxygen exchange equilibrium reaction is no longer reversible, while the internal defect equilibrium reactions (in particular, the electronic transfer processes) may still be reversible. For the partially frozen-in states as well as for the complete equilibrium cases, defect concentrations are numerically calculated for idealized model oxides including pure, acceptor-doped, and donor-doped oxides. Foreign ions (major/minor, shallow/deep, acceptor/donor), oxygen vacancies, and oxygen interstitials are taken into account as redox-active defects. The deep-level (redox-active) defects often dominate defect concentrations in the partially frozen-in states, while the major dopants fix the concentrations in complete equilibrium. The temperature and oxygen partial pressure dependencies of defect concentrations in the partially frozen-in states are discussed. The description does not only allow one to extend the defect chemistry to lower temperatures, such as room temperature, but also offers a quantitative basis for manipulation and prediction of defect concentrations in ionic crystals. Thereby, the physical and chemical performance of such materials may be controlled at temperatures lower than those at which the oxygen nonstoichiometry is established. The results are equally relevant for applications in solid state physics (e.g., compound semiconductors) and in solid state chemistry (e.g., solid electrolytes, mixed conductors). © 1999 American Institute of Physics.
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71.55.-i Impurity and defect levels
61.66.Bi Elemental solids
61.66.Dk Alloys
61.72.J- Point defects and defect clusters

Low-temperature defect chemistry of oxides. II. Analytical relations

K. Sasaki and J. Maier

J. Appl. Phys. 86, 5434 (1999); http://dx.doi.org/10.1063/1.371542 (10 pages) | Cited 10 times

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The low-temperature defect chemistry of oxides is considered, characterized by frozen-in interaction with the ambient oxygen and reversibility of internal interactions, in particular the redistribution of electronic carriers. Analytical relations describing ionic and electronic defect concentrations are derived for various conditions. The presence of redox-active, i.e., deep-level, dopants proves to be of special interest in this context. The analytical relations permit the detailed discussion of the dependencies of the charge carrier concentrations on the control parameters. Such analytical relations are useful for understanding and tailoring defect concentrations and thus related properties of electroceramics. © 1999 American Institute of Physics.
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71.55.-i Impurity and defect levels
61.72.-y Defects and impurities in crystals; microstructure

Structural and magnetic properties of a novel DyFe9.16V0.50 intermetallic compound with a disordered CaCu5-type structure

V. Psycharis, M. Gjoka, O. Kalogirou, N. Sheludko, N. Mikhov, E. Moraitakis, and D. Niarchos

J. Appl. Phys. 86, 5444 (1999); http://dx.doi.org/10.1063/1.371543 (6 pages)

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A Dy–Fe–V intermetallic compound has been prepared by arc melting elemental constituents, followed by annealing at 1123 K. This compound with a nominal composition of DyFe9.16V0.50, crystallizes in a disordered CaCu5-type structure (space group P6/mmm). Structure analysis is performed on x-ray powder diffraction data by the Rietveld method, and the lattice parameters are a = 4.8692(1) Å, c = 4.1750(3) Å. The calculated stoichiometric formula is Dy1.00(1)(Fe, V)9.9(2). Magnetic measurements give a Curie temperature of 473 K and a saturation magnetization Ms of 69.4 and 76.5 A m2/kg at 5 and 300 K, respectively. The fact that the Ms value is higher at higher temperatures is attributed to the ferrimagnetic structure of the compound. X-ray powder diffraction measurements on magnetically aligned powder show that the magnetocrystalline anisotropy is of an easy plane type at room temperature. ac susceptibility, magnetic polarization measurements and the calculation of the magnetocrystalline anisotropy constants confirm this result at room temperature and indicate that the magnetocrystalline anisotropy remains of an easy plane type over the whole temperature range between 5 and 300 K. © 1999 American Institute of Physics.
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75.50.Gg Ferrimagnetics
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.40.-s Critical-point effects, specific heats, short-range order
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Gw Magnetic anisotropy
61.66.Dk Alloys
75.30.Cr Saturation moments and magnetic susceptibilities

Reduction of ice adhesion to stainless steel by ice electrolysis

Victor F. Petrenko and Suogen Qi

J. Appl. Phys. 86, 5450 (1999); http://dx.doi.org/10.1063/1.371544 (5 pages) | Cited 1 time

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We report a very strong and reproducible effect of a small dc bias (−21 to +21 V) on ice adhesion to stainless steel. The effect was found in ice doped with 0.5% NaCl and was absent in very pure ice grown from deionized water. The doping was used to enhance ice electric conductivity. Neither the application of ac voltage nor direct electric heating of the same power as the dc bias caused any noticeable change in ice adhesion. Different physical mechanisms of ice adhesion to metals and possible explanations to the effect are discussed. Generation of electrolytic gases resulting in interfacial cracking is thought to be responsible for the effect. © 1999 American Institute of Physics.
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68.35.Gy Mechanical properties; surface strains
82.45.-h Electrochemistry and electrophoresis

Explosive compaction of Li-ion battery components

M. J. G. Jak, E. M. Kelder, J. Schoonman, V. N. Lashkov, A. V. Strikanov, A. A. Selezenev, and A. A. Potanin

J. Appl. Phys. 86, 5455 (1999); http://dx.doi.org/10.1063/1.371545 (6 pages) | Cited 1 time

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The compaction behavior of Li-ion battery components was studied by using explosive dynamic compaction. Dynamic compaction experiments were conducted on the cathode material LiMn2O4 and the ceramic electrolyte Li-doped BPO4. The compaction caused by the shock wave was studied by varying the compaction pressure and the compaction assembly. Densities up to 93.4% of the theoretical mass density were obtained without any heat treatment. A comparison between explosive compaction and magnetic pulse compaction as well as static pressing has been made. © 1999 American Institute of Physics.
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82.47.-a Applied electrochemistry
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)

Shock waves in basalt rock generated with high-powered lasers in a confined geometry

J. A. Bolger, C. S. Montross, and A. V. Rode

J. Appl. Phys. 86, 5461 (1999); http://dx.doi.org/10.1063/1.371546 (6 pages) | Cited 2 times

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An investigation was made into the interaction of Q-switched Nd: glass laser pulses, with energies of 5–100 J and intensities in the range of 1–15 GW cm−2, with thin slab samples of basalt, in a geometry in which the laser–matter interaction was enhanced by confining the laser-induced plasma and vapor against the rock surface with a thin water layer. The high pressure generated during expansion of the ablated material produced a shock wave which traveled into the rock. On basalt samples of thicknesses of up to 18 mm, reflection of the shock wave at the rear surface of the sample caused a thin rock layer to be spalled. Examination of the structure within the interior of the rock after laser exposure revealed extensive grain disruption near to the laser spot, due to the shock-wave passage. Rock specimens of thickness 50 mm were tested via Vickers hardness microindenter. The laser exposure was shown to produce a hardness decrease within the rock which was up to 50%, and extended to depths of 25 mm beneath the target position. An empirical model accounting for shock-wave formation and propagation was developed and compared to the experimental results. © 1999 American Institute of Physics.
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91.35.Gf Structure of the crust and upper mantle
62.50.-p High-pressure effects in solids and liquids
79.20.Ds Laser-beam impact phenomena

Ordering kinetics in Cu–Al–Ni shape memory alloys

V. Recarte, R. B. Pérez-Sáez, M. L. Nó, and J. San Juan

J. Appl. Phys. 86, 5467 (1999); http://dx.doi.org/10.1063/1.371547 (7 pages) | Cited 9 times

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The atomic order has a strong influence on the martensitic transformation behavior in Cu-based shape memory alloys. In this work we have studied the influence of the quenching and postquench aging treatments on the atomic order of the metastable β phase obtained by quenching in Cu–Al–Ni shape memory alloys by means of thermoelectric power (TEP) measurements. The initial evolution of TEP during aging shows two clear stages where TEP value decreases. These two TEP stages are interpreted as ordering processes at nearest neighbors (B2 order), and ordering processes at next nearest neighbors (L21 order), respectively. The analysis of the isothermal kinetics during aging at different temperatures has allowed us to determine the activation energies for both ordering processes. © 1999 American Institute of Physics.
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64.70.K- Solid-solid transitions
81.30.Kf Martensitic transformations
61.50.Ks Crystallographic aspects of phase transformations; pressure effects
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
81.40.Gh Other heat and thermomechanical treatments
72.15.Jf Thermoelectric and thermomagnetic effects

The multilayer-modified Stoney’s formula for laminated polymer composites on a silicon substrate

Jin S. Kim, Kyung W. Paik, and Seung H. Oh

J. Appl. Phys. 86, 5474 (1999); http://dx.doi.org/10.1063/1.371548 (6 pages) | Cited 14 times

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The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney’s formula has long been one of the most important tools for understanding thermomechanical stress for single-layered structures like spin-coated polyimides or deposited metal thin film on substrates. In today’s microelectronics, however, as multilayer substrates have become widely available, the “modified version” of Stoney’s formula for multilayer applications is not only useful but necessary. While the majority of reports in the literature have focused on single-layer analysis, in this study, we examined an extended usage of Stoney’s formula for multilayer analysis. A simple model, the multilayer-modified Stoney’s formula, which predicts the stress contribution of each individual layer is proposed and verified through experiments and numerical analysis. Using various kinds of materials employed in a typical lamination-based multichip module technology, the thermomechanical behavior of the lamination-based multilayer substrates was measured by a laser profilometry during thermal cycling. The measured values were compared with calculated values using the multilayer-modified Stoney’s formula. © 1999 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Segregation and diffusion of phosphorus from doped Si1−xGex films into silicon

S. Kobayashi, M. Iizuka, T. Aoki, N. Mikoshiba, M. Sakuraba, T. Matsuura, and J. Murota

J. Appl. Phys. 86, 5480 (1999); http://dx.doi.org/10.1063/1.371549 (4 pages) | Cited 6 times

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Segregation and diffusion of P from in situ doped Si1−xGex (0.25 ⩽ x ⩽ 0.8) epitaxial films into Si at 750–850 °C were investigated using secondary ion mass spectroscopy and differential resistance measurements. It was found that the surface P concentration in the diffused layer in Si was higher than the P concentration in the Si1−xGex film, which signifies the segregation of P from the Si1−xGex film into Si. The segregation coefficient, defined as the ratio of the active P concentration in the Si to that in the Si1−xGex film, was about 2.5 at 800 °C in the case of the Si0.75Ge0.25 film as a diffusion source and increased with increasing Ge fraction. It was found that the P diffusion profiles in Si were normalized by x/math, even though the segregation of P occurred, the diffusion coefficient of P depended on the surface P concentration, and the high concentration diffusion characteristics of P in Si were similar to those reported by using a conventional diffusion source. © 1999 American Institute of Physics.
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66.30.J- Diffusion of impurities
81.05.Cy Elemental semiconductors
64.75.-g Phase equilibria
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.30.Mh Solid-phase precipitation
68.35.Fx Diffusion; interface formation
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
61.72.S- Impurities in crystals

Lithium ion migration pathways in LiTi2(PO4)3 and related materials

Gerhard Nuspl, Tomonari Takeuchi, Armin Weiß, Hiroyuki Kageyama, Kazunari Yoshizawa, and Tokio Yamabe

J. Appl. Phys. 86, 5484 (1999); http://dx.doi.org/10.1063/1.371550 (8 pages) | Cited 6 times

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The diffusion pathways of Li+ ions within the frameworks of the high conductive solid electrolytes LiTi2(PO4)3 and the Al-doped one Li1.3Ti1.7Al0.3P3O12 are determined by molecular mechanics and molecular dynamics methods. From a potential energy profile for the lithium migration in LiTi2(PO4)3, the barrier height of lithium migration is estimated as 28.95 kJ/mol (0.30 eV) which is in excellent agreement with experimental data. The main influence on the activation energy of lithium diffusion is caused by changes in electrostatic interactions. Long molecular dynamics simulations for Li1.3Ti1.7Al0.3P3O12 also confirm a solid state diffusion process via rare and sporadic hopping of Li+ ions from their energy minimum site to a neighboring energy minimum site. © 1999 American Institute of Physics.
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66.30.H- Self-diffusion and ionic conduction in nonmetals
66.30.Dn Theory of diffusion and ionic conduction in solids

Selective adsorption of metallocenes on clean and chemically modified Si(111) surfaces

J.-L. Lin, H. Rauscher, A. Kirakosian, F. J. Himpsel, and P. A. Dowben

J. Appl. Phys. 86, 5492 (1999); http://dx.doi.org/10.1063/1.371551 (5 pages) | Cited 4 times

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Metallocene adsorption on clean Si(111) and CaF2/CaF1/Si(111) substrates has been investigated with scanning tunneling microscopy. The surface chemical composition is found to strongly change the adsorption site selectivity, leading to an enhanced edge selectivity on modified substrates. Templates with well-defined local chemical reactivity have been created via self-assembly. The selective adsorption of metallocenes on such tailored substrates facilitates patterning ordered arrays of magnetic nanowires and stripes on the single digit nanometer scale. © 1999 American Institute of Physics.
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
68.35.Dv Composition, segregation; defects and impurities
68.35.B- Structure of clean surfaces (and surface reconstruction)
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