jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter UniPHY Group iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

1 May 2001

Volume 89, Issue 9, pp. 4689-5231

Page 1 of 4 Pages Next Page | Jump to Page
back to top
RSS Feeds

Strained layer (111)B GaAs/InGaAs single quantum well lasers and the dependence of their characteristics upon indium composition

T. Fleischmann, M. Moran, M. Hopkinson, H. Meidia, G. J. Rees, A. G. Cullis, J. L. Sánchez-Rojas, and I. Izpura

J. Appl. Phys. 89, 4689 (2001); http://dx.doi.org/10.1063/1.1359155 (8 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied a series of (111) oriented GaAs–InGaAs single quantum well, broad area lasers with active regions containing a range of indium concentrations, x, in order to understand the advantages and limitations of pseudomorphic strain. For x⩽0.3, both an increased emission wavelength and reduced threshold current were observed with increasing x. The predominant cause of the wavelength increase is the reduction in bulk InGaAs band gap. The reduction in threshold current is attributed mainly to the reduced in-plane density of states caused by the strain induced lifting of the heavy and light hole degeneracy at the valence band edge. For x>0.3, we see a marked deterioration in laser performance. However, we believe that this deterioration is not directly associated with strain relaxation at layer thicknesses beyond the critical value. Rather, imperfections in the AlGaAs cladding layers appear to seed the formation of dislocations within the strained regions. Within the limitation of strain relaxation, we observed monomode continuous wave emission at room temperature at wavelengths up to 1.072 μm and with threshold current densities as low as 74 A/cm2. The differential gain of 1.45×10−15 cm2 is around four times higher than measured on unstrained GaAs/AlGaAs single quantum well lasers. Like the reduction in threshold current density, this relatively high value is attributed to the strain induced reduction in the in-plane, heavy hole effective mass. © 2001 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
73.21.Fg Quantum wells
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.65.Fg Quantum wells

Photoinduced surface deformations in ion-conducting Ag–As–S glasses. I. Isotropic deformations produced by small light spots

T. Gotoh and K. Tanaka

J. Appl. Phys. 89, 4697 (2001); http://dx.doi.org/10.1063/1.1357471 (6 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Prominent surface deformations appear in Ag–As–S chalcogenide glasses when exposed to focused laser beams. Deformation behaviors change with the beam diameter, the photon energy, the temperature at which illumination is provided, and the sample composition. In thin AgAsS2 films exposed at room temperature to a 2.0 eV light spot with a diameter of 2 μm, an isotropic convex structure with a height of ∼0.1 μm appears. The expanded region accompanies an Ag-content enhancement by ∼3 at. %, which suggests that the deformation is caused by photoinduced accumulation of Ag+ ions. © 2001 American Institute of Physics.
Show PACS
68.35.Gy Mechanical properties; surface strains
61.43.Fs Glasses
62.20.F- Deformation and plasticity
68.60.Bs Mechanical and acoustical properties
81.40.Lm Deformation, plasticity, and creep
66.30.H- Self-diffusion and ionic conduction in nonmetals

Photoinduced surface deformations in ion-conducting Ag–As–S glasses. II. Anisotropic deformation produced by large light spots

T. Gotoh and K. Tanaka

J. Appl. Phys. 89, 4703 (2001); http://dx.doi.org/10.1063/1.1357472 (4 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Anisotropic surface deformations appear in AgAsS2 chalcogenide films when exposed to linearly polarized 2.0 eV light spots with diameters of 5–200 μm. The anisotropic shape reflects the polarization direction. The shape also changes with the direction of light incidence. Illumination on the free surface of the films gives a craterlike deformation, and illumination through a substrate gives an anticrater deformation. In bulk samples, under any exposure conditions, an isotropic convex structure appears. The formation mechanisms of these patterns are discussed taking into account the photoinduced migration of Ag+ ions. © 2001 American Institute of Physics.
Show PACS
68.35.Gy Mechanical properties; surface strains
61.43.Fs Glasses
66.30.H- Self-diffusion and ionic conduction in nonmetals
68.60.Bs Mechanical and acoustical properties
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects

Identification of defects associated with second-order optical nonlinearity in thermally poled high-purity silica glasses

Akihiro Kameyama, Atsushi Yokotani, and Kou Kurosawa

J. Appl. Phys. 89, 4707 (2001); http://dx.doi.org/10.1063/1.1360214 (7 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A large second-order optical nonlinearity has been found to be generated in various kinds of silica glasses in which an even-order optical nonlinearity is inherently prohibited. Thermal poling is a typical procedure to generate such a second-order optical nonlinearity, but a mechanism behind the generation is not elucidated completely. It should be pointed out, however, that the nonlinearity was not added to high-purity silica glasses by poling. In this article, we show that the nonlinearity is generated in high-purity silica glasses irradiated by a KrF excimer laser before poling. We also show that the laser pulses erase the nonlinearity induced in the glasses. In addition to the laser irradiation effects on the generation and erasure, optical absorption and luminescence spectra in the glasses show that point defects of �Si–O− play a key role for the nonlinearity. © 2001 American Institute of Physics.
Show PACS
61.43.Fs Glasses
81.05.Kf Glasses (including metallic glasses)
42.65.-k Nonlinear optics
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
77.22.Ej Polarization and depolarization
back to top
RSS Feeds

Dual-electrode biasing for controlling ion-to-adatom flux ratio during ion-assisted deposition of diamond

Kungen Teii, Masaru Hori, and Toshio Goto

J. Appl. Phys. 89, 4714 (2001); http://dx.doi.org/10.1063/1.1359159 (5 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A dual-bias method using a grid mesh inserted into the front of a substrate has been employed to control the ion-to-adatom flux ratio in an inductively coupled plasma for depositing crystalline materials preferring low-energy ion bombardment. The Langmuir probe measurements revealed that the ion flux toward the substrate decreased with increasing a positive substrate bias with the grid grounded, while it increased with increasing a positive grid bias with the substrate grounded. Ion energy analyses along the diffusing plasma stream by using a probe and a mass spectrometer revealed the contribution of a high-energy tail in the ion-energy distribution into the bombarding ion flux. The ion-assisted deposition of diamond at a pressure of 10 mTorr was performed at a bombarding ion energy as low as the drifting energy (∼several eV). The results indicate the need for optimizing the ion-to-adatom flux ratio for efficient migration and clustering of precursor adatoms yielding a high nucleation density over 109 cm−2. © 2001 American Institute of Physics.
Show PACS
81.15.Jj Ion and electron beam-assisted deposition; ion plating
81.05.U- Carbon/carbon-based materials
81.05.Cy Elemental semiconductors
68.43.Mn Adsorption kinetics

Parametric study of the vacuum ultraviolet emission and electrical characteristics of a He–Xe microdischarge

Olivier B. Postel and Mark A. Cappelli

J. Appl. Phys. 89, 4719 (2001); http://dx.doi.org/10.1063/1.1355696 (8 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Vacuum ultraviolet emission and electrical characteristics of a simple discharge configuration consisting of two planar cylindrical electrodes operated with a dc voltage have been measured over a wide range of He/Xe mixtures and discharge pressures. Breakdown characteristics are consistent with those found in the literature, however current–voltage characteristics and the inferred discharge resistivity suggest the presence of a complex process controlling electron emission at the cathode. Ultraviolet vacuum emission maps of atomic and molecular xenon at 147, 150, and 173 nm, respectively, have been measured as a function of pressure, from 60 to 500 Torr, and gas mixture, from pure Xe to 5% Xe in He. The calibrated ratios of each emission map help to visualize the zones of strongest ultraviolet emission over a wide range of operating conditions. One-dimensional simulations of the breakdown voltage and current discharge have been performed using the commercially available discharge-modeling package SIGLO. Good agreement with experimental results is found in the case of pure helium and xenon, however, in the case of pure xenon, the gas temperature was adjusted (elevated) in order to reproduce the measured current–voltage characteristics. Modeling of the electron number density distribution indicates that the discharge is principally composed of a thick ion sheath near the cathode. © 2001 American Institute of Physics.
Show PACS
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.70.Ds Electric and magnetic measurements
51.50.+v Electrical properties (ionization, breakdown, electron and ion mobility, etc.)
52.25.Fi Transport properties
52.65.-y Plasma simulation
52.25.-b Plasma properties
52.40.Kh Plasma sheaths

Behavior of hydrogen atoms in ultrahigh-frequency silane plasma

Seigou Takashima, Masaru Hori, Toshio Goto, and Katsumi Yoneda

J. Appl. Phys. 89, 4727 (2001); http://dx.doi.org/10.1063/1.1362414 (5 pages) | Cited 17 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the behavior of the absolute density of hydrogen (H) atoms in ultrahigh-frequency (UHF), (500 MHz) silane (SiH4) plasma by using a vacuum ultraviolet absorption spectroscopy technique with a microdischarge hollow cathode lamp. In the UHF plasma using SiH4 highly diluted with hydrogen molecule (H2) at a pressure of 20 Pa, an UHF power of 1000 W, and a total flow rate of 200 sccm, the absolute density of H atoms slightly increased from 7.4×1011 to 7.9×1011 cm−3 with increasing the SiH4 flow rate ratios from 0% to 2.5% and then the H atom density decreased at the ratio of 5%. The decrease of the density is due to the increase of the reaction between the H atom and the SiH4 molecule. The behavior of the absolute density of H atoms was compared with that of the Balmer α(Hα) emission intensity. It was found that the behaviors of the absolute H atom density and the Hα emission intensity were quite different. Moreover, the kinetics of H atom density in SiH4 plasmas have been clarified on the basis of measured results. © 2001 American Institute of Physics.
Show PACS
52.25.-b Plasma properties
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Concentration dependence of gas discharge around drops of inorganic electrolytes

K. G. Korotkov and D. A. Korotkin

J. Appl. Phys. 89, 4732 (2001); http://dx.doi.org/10.1063/1.1360700 (5 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This article is devoted to the study of image formation in gas discharge, initiated by a strong impulsive electromagnetic field around drops of four different nonorganic electrolytes. To describe the image mathematically we propose several parameters: the form coefficient (fractality), the entropy, and the average streamer width. We study the dependence of these parameters on concentration. The form coefficient turns out to have the best combination of stability and sensitivity in the whole range of concentrations. Statistically significant difference between the solutions and distilled water disappears at concentrations of about 2−20 N. © 2001 American Institute of Physics.
Show PACS
52.80.-s Electric discharges

Time evolution of colliding laser produced magnesium plasmas investigated using a pinhole camera

S. S. Harilal, C. V. Bindhu, and H.-J. Kunze

J. Appl. Phys. 89, 4737 (2001); http://dx.doi.org/10.1063/1.1362408 (4 pages) | Cited 19 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Time resolved studies of colliding laser produced magnesium plasmas are performed using a pinhole camera. A ruby laser pulse is split into two beams using a movable glass wedge and focused onto a planar target or targets placed at 90° to each other. A gated pinhole camera provides an orthogonal view of the collision. Measurements with an aluminum filter allowed identification of soft x-ray production zones. A good interpenetration of the two plasmas was observed in the 90° target geometry, because of higher relative velocities, than in the case of laterally colliding plasmas. The appearance of the collision region depended strongly on the power density and on the separation of the foci on the target surfaces. © 2001 American Institute of Physics.
Show PACS
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.38.Ph X-ray, γ-ray, and particle generation
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

Optical parameters of a magnetized semiconductor plasma with nonparabolic band structure

Giriraj Sharma and S. Ghosh

J. Appl. Phys. 89, 4741 (2001); http://dx.doi.org/10.1063/1.1358315 (6 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The optical parameters (linear and nonlinear) and dispersion characteristics of a III–V compound semiconductor plasma subjected to a strong transverse magnetic field have been investigated theoretically. The nonlinearity induced in the medium has been attributed to heating of the carriers by the pump that results in modification of the electron effective mass in a nonparabolic conduction band and the momentum transfer collision frequency of electrons. The external magnetic field is found to have two consequences: (a) increasing the nonlinearity of the medium and (b) modifying the dispersion characteristics and determining the direction of energy flow between the pump and the generated waves. The plasma frequency ωp is found to enhance the magnitude of the optical parameters as usual. For a typical n-InSb semiconductor, linear refractive index and nonlinear refractive index coefficients are found maximum (nl=5.3, nnl=2×10−10 m2 V−2) whereas absorption coefficients al (linear) and anl (nonlinear) are found to vanish when ωo resonates with ωc(=1.138×1014 s−1). The present study once again establishes the device potentials of n-InSb. © 2001 American Institute of Physics.
Show PACS
72.30.+q High-frequency effects; plasma effects
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
42.25.Bs Wave propagation, transmission and absorption
71.20.Nr Semiconductor compounds
back to top
RSS Feeds

Planar nematic anchoring due to a periodic surface potential

Bing Wen and Charles Rosenblatt

J. Appl. Phys. 89, 4747 (2001); http://dx.doi.org/10.1063/1.1359757 (5 pages) | Cited 18 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A polyimide-coated substrate is rubbed periodically with the stylus of an atomic-force microscope. The effective polar and azimuthal anchoring strength coefficients for planar anchoring are determined as a function of the spatial separation L of rub lines. Both anchoring coefficients are found to decrease monotonically with L, apparently leveling off at nonzero values for L≳2 μm. The observed behavior is discussed in terms of a combination of intrinsic anchoring strength in the rubbed regions and a surface memory effect. © 2001 American Institute of Physics.
Show PACS
61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures

Evolution of point defect clusters in pure iron under low-energy He+ irradiation

K. Arakawa, R. Imamura, K. Ohota, and K. Ono

J. Appl. Phys. 89, 4752 (2001); http://dx.doi.org/10.1063/1.1357785 (6 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The formation process of point defect clusters in high-purity (99.999%) iron as a typical bcc metal under the irradiation with low-energy (5 keV)He+ is studied by in situ transmission electron microscopy (TEM). Using conventional TEM techniques, clusters induced by the irradiation are determined to be interstitial-type dislocation loops (I loops) at temperatures ranging from 85 to 770 K and cavities from 300 to 770 K. Most of the I loops are determined to lie on {100} planes, and their Burgers vector are determined to be a[100]. The temporal variation in the volume density of I loops is measured by stereomicroscopy at several temperatures. The volume density of I loops is about two orders of magnitude higher in comparison with the case of high-energy electron irradiation at the same dpa rate; hence, it is deduced that helium atoms have an effect enhancing the nucleation of I loops. The depth distribution of the loop densities becomes broad above around 235 K at which vacancies become thermally mobile, and the dependence of loop formation on He+ beam flux is weak. From these results, it is suggested that helium-vacancy complexes act as trapping sites of self-interstitial atoms and I-loop nucleation is enhanced. © 2001 American Institute of Physics.
Show PACS
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.80.Jh Ion radiation effects
61.82.Bg Metals and alloys
61.72.J- Point defects and defect clusters
61.72.Lk Linear defects: dislocations, disclinations
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Modeling of vacancy cluster formation in ion implanted silicon

Srinivasan Chakravarthi and Scott T. Dunham

J. Appl. Phys. 89, 4758 (2001); http://dx.doi.org/10.1063/1.1352680 (8 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ion implantation of silicon introduces excess point defects that quickly recombine during annealing leaving net interstitial and vacancy populations. For higher energy implants, the separation between interstitials and vacancies is larger, leading to a vacancy rich region towards the surface and an interstitial rich region deeper in the bulk. The high supersaturation of vacancies in the near surface region can lead to their aggregation into vacancy clusters or voids. In this work we have developed a continuum model for vacancy clusters using discrete cluster sizes. Results from atomistic calculations [Bongiorno et al., Europhys. Lett. 43, 695 (1998)] are used for the energetics of the cluster growth/dissolution. The model is compared to data from Venezia et al. [Appl. Phys. Lett. 73, 2980 (1998)] for Au indiffusion subsequent to Si high energy implants. We found good agreement with experimental data using this model without any tuning of the parameters. However, this model is too complex and computationally expensive to be effectively incorporated into continuum process simulation tools. Hence we reduced this system of discrete rate equations into a two-moment model by carefully considering the behavior of the full model under a range of conditions. The parameters of the moment-based model follows from the full model, which in turn is based on atomistic calculations. The resulting simple and computationally efficient model is found to accurately reproduce the Au labeling experiments. © 2001 American Institute of Physics.
Show PACS
61.72.J- Point defects and defect clusters
81.05.Cy Elemental semiconductors
85.40.Ry Impurity doping, diffusion and ion implantation technology
61.72.Cc Kinetics of defect formation and annealing
61.72.uf Ge and Si
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Ultrashort pulse ultraviolet laser treatment of n(100) GaAs: Microstructural modifications and passivation effects

T. A. Railkar, A. P. Malshe, W. D. Brown, Shiva S. Hullavarad, and S. V. Bhoraskar

J. Appl. Phys. 89, 4766 (2001); http://dx.doi.org/10.1063/1.1359752 (6 pages) | Cited 2 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Gallium arsenide (GaAs) is one of the most important materials among the III–V family, especially in view of its applicability to optoelectronic devices. However, it is known that GaAs, unlike silicon (Si), does not possess a stable native oxide that can passivate and protect the surface. This article reports the use of femtosecond (fs) laser-based modification and passivation of the GaAs surface, where femtosecond laser-based processing was shown to be particularly useful, effective, and more convenient compared to conventional laser treatment. The fs laser treatment involves an almost nonexistent heat affected zone, which implies that there is virtually no thermal damage to the volume of material surrounding a processed region. The surface passivating effects were confirmed by depth-profiling x-ray photoelectron spectroscopic measurements. In addition, scanning electron microscopy and atomic force microscopy measurements lead to a possible explanation of the passivation mechanism. Further, a relatively novel technique called thermally stimulated exoelectron emission was used to verify the existence of surface passivation. This measurement technique detects “cold electron emission” from trapping centers at the surface of material under scrutiny. © 2001 American Institute of Physics.
Show PACS
81.05.Ea III-V semiconductors
81.65.Rv Passivation
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Fk Semiconductors
72.80.Ey III-V and II-VI semiconductors
73.61.Ey III-V semiconductors
79.20.Ds Laser-beam impact phenomena
61.72.-y Defects and impurities in crystals; microstructure
68.35.B- Structure of clean surfaces (and surface reconstruction)

Surface structure of niobium-dioxide overlayer on niobium(100) identified by scanning tunneling microscopy

Y. Li, B. An, X. Xu, S. Fukuyama, K. Yokogawa, and M. Yoshimura

J. Appl. Phys. 89, 4772 (2001); http://dx.doi.org/10.1063/1.1364649 (5 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The surface structures of an oxide overlayer on Nb(100) single crystal formed by numerous cycles of Ar-ion sputtering and flash annealing at 1973 K in an ultra-high-vacuum chamber have been investigated by scanning tunneling microscopy. Flat terraces with a monatomic step height of Nb(100) are observed; where two orthogonal domains are alternately evident. A ladder-like (3×10) structure of Nb(100) with no long-range order is identified at atomic resolution in the domain on the terrace. The ladder-like (3×10) structure is interpreted to be a modulated NbO2(010) overlayer on the Nb(100) surface and an atomic structural model of the ladder-like (3×10) structure is proposed. © 2001 American Institute of Physics.
Show PACS
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.49.Sf Ion scattering from surfaces (charge transfer, sputtering, SIMS)
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
61.72.Cc Kinetics of defect formation and annealing

Approximate description of the two-dimensional director field in a liquid crystal display

G. Panasyuk, D. W. Allender, and J. Kelly

J. Appl. Phys. 89, 4777 (2001); http://dx.doi.org/10.1063/1.1359423 (10 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A model for describing properties of a liquid crystal display which combines the concepts of in-plane switching and vertical alignment is proposed. There is good agreement between the results of this model and direct computer calculation of the director and the light transmittance. The usefulness of the model lies in the faster speed of calculations compared to direct computer solution of the Euler–Lagrange equations. © 2001 American Institute of Physics.
Show PACS
42.79.Kr Display devices, liquid-crystal devices
78.20.Jq Electro-optical effects

Stress dependent activation entropy for dynamic fatigue of pristine silica optical fibers

Y. S. Shiue and M. J. Matthewson

J. Appl. Phys. 89, 4787 (2001); http://dx.doi.org/10.1063/1.1361245 (7 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Subcritical crack growth in fused silica is treated as a stress assisted chemical reaction between water and strained bonds at the crack tip. In this work, the kinetics of the reaction is modeled by assuming the stress reduces the energy barrier of the activated complex by affecting both the activation enthalpy and entropy, where the stress dependence can take different forms. This theory is compared with dynamic fatigue data obtained for pristine fused silica optical fiber. The experiments were conducted in both distilled water and pH 7 buffer solution, and the results are found to be similar. The fatigue parameters were found by fitting to three different forms for the stress dependence; the activation enthalpy and entropy were then determined from the fatigue parameters. It is found that stress increases the activation entropy, whichever kinetic form is used, and thereby reduces the activation energy barrier height. The activation enthalpy is also stress dependent, but stress tends to increase the enthalpy contribution to the barrier height. The results show subcritical crack growth in high strength silica is dominated by entropy effects. © 2001 American Institute of Physics.
Show PACS
42.81.-i Fiber optics
62.20.M- Structural failure of materials
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure

Nanocrystalline iron at high pressure

B. Chen, D. Penwell, M. B. Kruger, A. F. Yue, and B. Fultz

J. Appl. Phys. 89, 4794 (2001); http://dx.doi.org/10.1063/1.1357780 (3 pages) | Cited 16 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
X-ray diffraction measurements were performed on nanocrystalline iron up to 46 GPa. For nanocrystalline ϵ-Fe, analysis of lattice parameter data provides a bulk modulus, K, of 179±8 GPa and a pressure derivative of the bulk modulus, K′, of 3.6±0.7, similar to the large-grained control sample. The extrapolated zero-pressure unit cell volume of nanocrystalline ϵ-Fe is 22.9±0.2 Å3, compared to 22.3±0.2 Å3 for large-grained ϵ-Fe. No significant grain growth was observed to occur under pressure. © 2001 American Institute of Physics.
Show PACS
75.50.Bb Fe and its alloys
61.46.-w Structure of nanoscale materials
75.50.Tt Fine-particle systems; nanocrystalline materials
81.07.Bc Nanocrystalline materials
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity
61.66.Bi Elemental solids

Lattice softening and failure in severely deformed molecular crystals

C. S. Coffey and J. Sharma

J. Appl. Phys. 89, 4797 (2001); http://dx.doi.org/10.1063/1.1358319 (6 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Atomic force microscope observations have revealed the presence of permanent lattice and molecular distortions in molecular crystals that had undergone plastic deformation by shock or impact. These distortions have led to the suggestion of a deformed lattice potential. Here, the deformed lattice potential is extended to the case of severe plastic deformation in which the lattice softens and may eventually fail. This generalized lattice potential has been incorporated into descriptions of plastic flow and the associated energy dissipation due to dislocation motion by quantum tunneling. The resultant predictions are compared with experiments in which molecular crystals were subjected to severe plastic deformation during impact. © 2001 American Institute of Physics.
Show PACS
46.35.+z Viscoelasticity, plasticity, viscoplasticity
62.20.F- Deformation and plasticity
61.72.Lk Linear defects: dislocations, disclinations
66.30.Lw Diffusion of other defects
62.50.-p High-pressure effects in solids and liquids

Oxygen-dislocation interactions in silicon at temperatures below 700 °C: Dislocation locking and oxygen diffusion

S. Senkader, P. R. Wilshaw, and R. J. Falster

J. Appl. Phys. 89, 4803 (2001); http://dx.doi.org/10.1063/1.1359424 (6 pages) | Cited 22 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The locking of dislocations by oxygen atoms in Czochralski–silicon at temperatures between 350 and 700 °C has been studied. Both experimental and theoretical investigations were carried out for different oxygen concentrations, different annealing times (from 10 to 3×107 s), and different point defect concentrations. It was found that the unlocking stress of dislocations at low temperatures follows similar trends to those previously observed at higher temperatures and is determined by annealing temperature, time, and oxygen concentration. However, in the present temperature range, experimental results indicate an enhanced transport of oxygen to dislocations. Numerical simulations solving the diffusion equation for oxygen transport to the dislocations show that the effective diffusivity of oxygen at lower temperatures diverges from “normal” diffusivity of oxygen. We have shown that oxygen transport can be as much as three orders of magnitude higher than that which would be assumed by extrapolation of the “normal” data obtained at higher temperatures. In the low temperature regime the effective diffusivity is dependent on the oxygen concentration and has an activation energy of about 1.5 eV. © 2001 American Institute of Physics.
Show PACS
61.72.Yx Interaction between different crystal defects; gettering effect
81.10.Fq Growth from melts; zone melting and refining
61.72.Bb Theories and models of crystal defects
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Cc Kinetics of defect formation and annealing
66.30.J- Diffusion of impurities
61.72.S- Impurities in crystals

Driving force for adatom electromigration within mixed Cu/Al overlayers on Al(111)

P. J. Rous

J. Appl. Phys. 89, 4809 (2001); http://dx.doi.org/10.1063/1.1325385 (6 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A multiple scattering theory is used to study the effect of the addition of Cu upon the driving force for the electromigration of Al adatoms on an Al(111) surface. The theory employs a computational framework that combines a layer-Korringa Kohn–Rostoker calculation with the coherent potential approximation to describe the carrier scattering by a compositionally disordered overlayer. We investigate how the substitution of Cu for Al adatoms in the disordered overlayer alters the average effective wind valence of the Al and Cu adatoms within the overlayer. For adatom coverages smaller than approximately 0.2, we find that the effect of Cu substitution is to reduce the magnitude average effective wind valence of the Al adatoms by approximately +0.4%(Cu)−1 at 273 K. © 2001 American Institute of Physics.
Show PACS
66.30.Qa Electromigration
68.35.Fx Diffusion; interface formation

InGaAs/InP quantum well intermixing studied by cross-sectional scanning tunneling microscopy

Huajie Chen, H. A. McKay, R. M. Feenstra, G. C. Aers, P. J. Poole, R. L. Williams, S. Charbonneau, P. G. Piva, T. W. Simpson, and I. V. Mitchell

J. Appl. Phys. 89, 4815 (2001); http://dx.doi.org/10.1063/1.1361237 (9 pages) | Cited 20 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Cross-sectional scanning tunneling microscopy (STM) is used to study lattice matched InGaAs/InP quantum well (QW) intermixing induced by ion implantation and thermal annealing. Different strain development in QWs (determined by STM topography of elastic relaxation in cross sectionally cleaved samples) is found to be dependent upon the range of the implanted ions relative to the QWs. It is found that the quantum wells remain latticed matched to the barrier layers after intermixing when ions are implanted through the multiple quantum well (MQW) stack. A shallow implantation in which ions are implanted into the cap layer above the MQW stack leads to tensilely strained wells and compressively strained interfaces between wells and barriers. The strain development in the latter case is attributed to different degrees of interdiffusion on the group III and group V sublattices. Finite element elastic computations are used to extract the group V and group III interdiffusion length ratio, and results using different diffusion models are compared. A preferred group V interdiffusion in the case of shallow implantation is explained in terms of faster diffusing P related defects compared to In related defects. Images of as-grown QWs provide useful information about the growth technique related compositional fluctuations at the interfaces. © 2001 American Institute of Physics.
Show PACS
68.35.Fx Diffusion; interface formation
61.72.Cc Kinetics of defect formation and annealing
61.72.uj III-V and II-VI semiconductors
68.65.Fg Quantum wells
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors

Effective medium calculation of creep of fiber reinforced composites

S. T. Chui

J. Appl. Phys. 89, 4824 (2001); http://dx.doi.org/10.1063/1.1357778 (6 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effective creep rate of fiber reinforced composites in an effective medium approximation is calculated analytically. The fibers are modeled by ellipsoids of a given aspect ratio. Both the case of aligned and randomly oriented ellipsoids are investigated. The elastic strains are calculated along the previous work of [J. D. Eshelby, Proc. R. Soc. London, Ser. A 241, 376 (1957)]. I find that different amounts of the reinforcement is to change the time scale of change. The functional form remains unchanged. © 2001 American Institute of Physics.
Show PACS
62.20.Hg Creep
81.40.Lm Deformation, plasticity, and creep

Comparative study on the effects of ion density and ion energy on diamond-like carbon deposited by electron cyclotron resonance chemical vapor deposition

S. F. Yoon, K. H. Tan, Rusli, J. Ahn, and Q. F. Huang

J. Appl. Phys. 89, 4830 (2001); http://dx.doi.org/10.1063/1.1359163 (6 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Diamond-like carbon films were deposited using electron cyclotron resonance (ECR) chemical vapor deposition incorporated with a screen grid under different dc bias voltages to compare the effect of ion density and ion energy on the film properties. Langmuir probe measurements and optical emission spectroscopy were used to characterize the ECR plasma, while the films were characterized using Raman and infrared (IR) spectroscopies, hardness, and optical gap measurements. The plasma measurements showed that the ion density, hydrogen atom density, and CH density decreased monotonously following increase in the dc bias voltage. Raman spectra and optical gap measurements indicate the films became more graphitic with lower content of sp3-hybridized carbon atoms as the dc bias voltage was increased. An increase in hydrogen content was found in films prepared at relatively high dc bias voltage, as indicated by IR measurements. Films deposited at −150 V exhibit maximum hardness. The results show the ion density has a stronger effect on the film deposition rate and hydrogen content, while the ion energy affects the film properties more predominantly by changing the bonding structure. © 2001 American Institute of Physics.
Show PACS
81.05.U- Carbon/carbon-based materials
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.66.Nk Insulators

X-ray reflectivity of self-assembled structures in SiGe multilayers and comparison with atomic force microscopy

M. Meduňa, V. Holý, T. Roch, J. Stangl, G. Bauer, J. Zhu, K. Brunner, and G. Abstreiter

J. Appl. Phys. 89, 4836 (2001); http://dx.doi.org/10.1063/1.1359156 (7 pages) | Cited 2 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied the interface morphology of SiGe/Si multilayers by means of specular and nonspecular x-ray reflectivity under grazing incidence. The samples were grown by molecular beam epitaxy on silicon substrates with (001) surface orientation and with different directions of the surface misorientation. X-ray reflectivity measurements in different azimuths are compared to data from atomic force microscopy, which are used to simulate the x-ray experiments. With this combination of experimental techniques we have determined the structural properties, in particular the ordering of different features present at the sample surface and inside the multilayer at the SiGe/Si layer interfaces. © 2001 American Institute of Physics.
Show PACS
68.65.Cd Superlattices
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.Ct Interface structure and roughness
68.37.Yz X-ray microscopy
Page 1 of 4 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Your Recent History Recent History Help

Recently Viewed

  1. Improved refractive index formulas for the AlxGa1−xN and InyGa1−yN alloys
  2. Band parameters for III–V compound semiconductors and their alloys
  3. Rate and efficiency of spontaneous emission in metal-clad microcavities
  4. Nanostructure magneto-optical thin films of rare earth (RE=Gd,Tb,Dy) doped cobalt spinel by sol–gel synthesis
  5. Effects of stacking faults on magnetic viscosity in thin film magnetic recording media
Go to AIP Home
Copyright © American Institute of Physics
close