By Topic

Journal of Applied Physics

Issue 3 • Date Feb 1992

Filter Results

Displaying Results 1 - 25 of 78
  • Issue Table of Contents

    Page(s): toc1
    Save to Project icon | PDF file iconPDF (387 KB)  
    Freely Available from IEEE
  • Electron‐paramagnetic‐resonance study of silver halide photochromic glasses: Darkening mechanism

    Page(s): 1081 - 1090
    Save to Project icon | PDF file iconPDF (1289 KB)  

    The mechanism of darkening of standard silver halide photochromic glass is studied by electron paramagnetic resonance (EPR) of photogenerated divalent copper ions. A time resolution of the EPR spectra was obtained by recording the evolution with the irradiation time of the EPR intensity at various magnetic‐field strengths. It is shown that only one copper species is photogenerated during darkening. This species is a CuII‐silver vacancy complex oriented along a [110] direction. The electron ground state has a predominantly dz2 character. The activation energy of the formation of this complex, E=0.06±0.01 eV, is controlled by the migration of interstitial silver ions. It is also shown that the silver vacancy of the complex is generated during the hole trapping by the monovalent copper ion. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Beam divergence effects on nonlinear frequency mixing

    Page(s): 1091 - 1101
    Save to Project icon | PDF file iconPDF (1253 KB)  

    The effects of the beam divergence of the input pump laser beams on the nonlinear frequency mixing process in a dielectric medium is discussed. The divergent laser beams have finite angular spreads so that all of the interactions between the two input beams can never satisfy the phase‐matching condition exactly. A numerical model is developed to investigate the effects of input beam divergence on conversion efficiency. The angular spread of each of the input beams is represented by a set of plane waves having a distribution of propagation directions. Each of the plane‐wave components from one input beam is allowed to interact with all the plane‐wave components of the second input beam. This model is applicable to processes such as sum frequency generation, difference frequency generation, and optical parametric amplification. Second‐harmonic generations as a special case of sum frequency generation is used as an example in the numerical studies. Results indicate that the conversion efficiency is dependent on the amount of beam divergence, the input intensity, and the length of the nonlinear medium. These parameters must be optimized with respect to one another to maximize the conversion. The optimization is especially critical in high‐power systems where high conversion efficiency is sought. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Generalized perturbation analysis of distortion in semiconductor lasers

    Page(s): 1102 - 1108
    Save to Project icon | PDF file iconPDF (726 KB)  

    We have carried out a generalized perturbation analysis of the second‐order nonlinear equation for photon density for semiconductor lasers. The second‐order equation is obtained with minimal approximations, from the single‐mode semiconductor laser rate equations, which unlike previous work, include both the effect of gain compression and the coupling of the spontaneous emission to the lasing mode. After deriving the general perturbation formula, expressions for second harmonic distortion as well as third‐order intermodulation distortion are obtained. Unlike previous work which is restricted to two subcarriers, the present work gives results for an arbitrary number of subcarriers. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Three‐dimensional simulation of dye laser amplifiers

    Page(s): 1109 - 1115
    Save to Project icon | PDF file iconPDF (734 KB)  

    A time‐dependent and three‐dimensional dye laser amplifier simulation is presented. Its amplified spontaneous emission (ASE) is simulated by distinguishing the propagating directions of the angularly divided ASE, which makes it possible to simulate both the laser and ASE. Strong generation of the ASE is seen from the part of the excited volume where there is no input signal, indicating that ASE greatly depends on the input‐beam geometrical profile, as well as its temporal matching with the pumping beam. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nanosecond photothermal dynamics in colloidal suspension

    Page(s): 1116 - 1123
    Save to Project icon | PDF file iconPDF (846 KB)  

    Thermal diffusion from a single colloidal sphere suspended in an aqueous medium that is heated by a laser pulse is examined. The temperature field as a function of position and time arising from the cooling of a hot colloidal sphere suspended in an infinitely extended aqueous medium is obtained by solving the heat conduction equation with initial, asymptotic, boundary conditions using a Laplace transform technique. A polymethylmethacrylate sphere of 83 nm diameter is calculated to cool in water within 7 ns. The cooling time is found to decrease quadratically with the particle diameter. We discuss the use of arrays of dyed polymethylmethacrylate spheres suspended in a refractive‐index‐matched aqueous medium as a fast (ns) optical switching device which acts as an optical monostable. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Laser beam propagation through strong turbulence

    Page(s): 1124 - 1127
    Save to Project icon | PDF file iconPDF (361 KB)  

    The effects of strong turbulence (C2n up to 3×10-9 m-2/3) on laser beam propagation were measured. Beam broadening of a factor of 2, and wander over several hundred microradians were observed. Long‐term beam broadening agrees with values calculated from simplified analytic models. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pressure‐temperature effects in planar Stefan problems with density change

    Page(s): 1128 - 1137
    Save to Project icon | PDF file iconPDF (1170 KB)  

    An extension of the classical thermal Stefan problem by incorporating the dependence of the phase transition temperature on pressure generated by the flow of the liquid phase due to a density change in the transition process is presented. Two prototypical planar situations are considered. The first is the onset of freezing in an incompressible liquid layer of finite thickness in a gravity field. Asymptotic solutions developed for this problem demonstrate that the initial singularities of the interface velocity and acceleration, typical for the solutions of the classical Stefan problem with an instantaneous temperature drop at the fixed boundary, are regularized by the dynamic pressure effect. The second problem addressed is the freezing or melting of a saturated porous half‐space with a flow governed by the Darcy law. Exact similarity solutions (accounting for compressibility of the fluid in the case of freezing) are developed. They indicate that the pressure dependence of the transition temperature may affect significantly the propagation of the phase‐change front. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the correspondence between poroelasticity and thermoelasticity

    Page(s): 1138 - 1141
    Save to Project icon | PDF file iconPDF (510 KB)  

    An interesting and useful analogy can be drawn between the equations of static poroelasticity and the equations of thermoelasticity including entropy. The correspondence is of practical use in determining the effective parameters in an inhomogeneous poroelastic medium using known results from the literature on the effective thermal expansion coefficient and the effective heat capacity of a disordered thermoelastic continuum. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Behavior of charged and uncharged bubbles in dielectric liquids subjected to electric stress

    Page(s): 1142 - 1145
    Save to Project icon | PDF file iconPDF (462 KB)  

    This paper is devoted to the calculation of the electric traction Pe acting at every point on the surface of a charged gas or liquid bubble immersed in an insulating liquid and subjected to an electric field between parallel‐plate electrodes. It is shown that the deformation of a bubble charged or situated near the electrodes is not symmetric. This dissymmetry has been verified experimentally. The expression for Pe used in a previous work [C. G. Garton and Z. Krasucki, Proc. R. Soc. London Ser. A 280, 211 (1964)] represents a particular case (bubble uncharged or electrically neutral) of the one we have established. In this case, the shape of the distorted bubble is that of a prolate spheroid. This deformation of bubbles also depends on their concentration and positions in the electrode gap. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cross‐talk between neighboring pulse discharges in gas discharge displays

    Page(s): 1146 - 1152
    Save to Project icon | PDF file iconPDF (751 KB)  

    Simultaneous pulsing of two, closely spaced discharge tubes inhibits the ignition of one of the discharges. Such cross‐talk is prominent for discharge tubes having a floating cathode potential (i.e., with an impedance attached to the cathode), driven by short duration pulses, and having a long discharge path. The cross‐talk originates from at least two mechanisms. First, a voltage jump at the cathode, induced by a capacitive coupling with another cathode, makes the anode‐cathode potential smaller, and hence discharge ignition is inhibited. Second, wall charges induced by a discharge in a neighboring tube also inhibit ignition. The cross‐talk can adversely affect the operation of gas discharge displays. It is demonstrated that cross‐talk in the panel can be eliminated by adopting a dephasing drive technique.   View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • X‐ray generation from 50‐mJ, 120‐ps KrF laser‐produced plasmas

    Page(s): 1153 - 1162
    Save to Project icon | PDF file iconPDF (1067 KB)  

    The generation of x rays from the interaction of low‐energy (10–50 mJ) 120‐ps KrF laser pulses with solid targets has been experimentally investigated. Conversion efficiency as a function of laser energy and detailed keV x‐ray spectra have been obtained for targets (Fe, Ni, and Cu) with potential application in high‐resolution x‐ray lithography. Peak x‐ray conversion efficiencies of over 3% in the 800–1400‐eV photon energy band have been measured for laser intensities of 1.5 × 1014 W/cm2. In addition, transmission grating spectra have been obtained to characterize the overall distribution of x‐ray emission at photon energies down to 100 eV. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A high‐current‐density nonclosing plasma cathode

    Page(s): 1163 - 1170
    Save to Project icon | PDF file iconPDF (1063 KB)  

    A novel plasma cathode has been demonstrated. Its operation depends on the presence of a magnetic field and requires a low‐pressure burst of gas to form a crossed‐field discharge. The electron current that can be extracted is controlled by the discharge current. When the extracted current is less than the space‐charge limit there is no diode closure. The fundamental characteristics of intense crossed‐field discharges are measured, and cathode tests up to 6 A cm-2 at 100 kV are reported, in a 100‐cm2 cathode with 5‐μs pulses. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electrical isolation of radio‐frequency plasma discharges

    Page(s): 1171 - 1176
    Save to Project icon | PDF file iconPDF (790 KB)  

    Plasmas used for processing of microelectronics materials are often powered by radio‐frequency (rf) electrical sources. Such plasmas have nonlinear impedance characteristics which cause the plasma state to depend on the nature of the circuitry that supplies electrical power to the plasma. This dependency occurs because the harmonics of the fundamental drive frequency, which are generated by the plasma nonlinearity, interact with the impedance of the external circuitry at the harmonic frequencies. This report describes the successful use of an rf filter in the power feed to the plasma which isolates the plasma electrically and eliminates its sensitivity to changes in the rf generator, cable plant, and matching network. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effects of ionization on the presheath in flowing magnetized plasma

    Page(s): 1177 - 1181
    Save to Project icon | PDF file iconPDF (652 KB)  

    The effect of ionization on the presheath is analyzed kinetically in flowing magnetized plasma with finite ion temperature. Ion distributions along the presheath are obtained self‐consistently with Boltzmann electrons. Sheath potential, ion sheath current density, and ratio (R) of upstream to downstream current density are obtained as a function of plasma drift velocity (Vd) and ionization rate (σi). Calibration factor (K) in the form of R=exp[KM] decreases with σi, where M is the drift velocity in units of [(ZTe + Ti∞)/mi]0.5. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Deep levels in γ‐ray irradiated n‐ and p‐type hydrogen‐grown float‐zoned silicon

    Page(s): 1182 - 1188
    Save to Project icon | PDF file iconPDF (808 KB)  

    The generation rates and annealing behavior of the irradiation defects in n‐ and p‐type hydrogen‐grown float‐zoned silicon (irradiated with γ rays from 60Co) have been studied by the deep‐level transient spectroscopy technique and compared with those of irradiated argon‐grown float‐zoned silicon. Assuming the generation rate of the irradiation defects created by γ rays in argon‐grown float‐zoned silicon is 1, then the generation rates of the A center, divacancy, and phosphorus vacancy in n‐type hydrogen‐grown float‐zoned silicon are 0.23, 0.78, and 0.19, respectively, while the generation rates of the divacancy and H(0.37 eV) in p‐type hydrogen‐grown silicon are 0.79 and 0.10, respectively. Due to the existence of hydrogen, the generation rate reduction of the major irradiation defects in γ‐ray irradiated silicon is more pronounced than that in 1‐MeV electron irradiated silicon. Three hydrogen‐related defects, H(0.10 eV), H(0.29 eV), and H(0.56 eV), were seen in γ‐ray irradiated hydrogen‐grown float‐zoned silicon, among which H(0.10 eV) and H(0.56 eV) were reported by us to exist in electron irradiated hydrogen‐grown float‐zoned silicon, while H(0.29 eV) is reported for the first time. The convergence effect of annealing temperatures for the irradiation defects was observed. That is, the annealing temperatures at which the irradiation defects diminish are almost the same for most irradiation defects, similar to that in the case of electron irradiation, was observed, showing that this effect is characteristic of the hydrogen behavior in silicon, and irrelevent to the type of irradiation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Evaluation of In1-xGaxAs/In1-yGayAs strained layer superlattice structures by x‐ray diffraction measurements with a novel discrimination method of the fundamental peak

    Page(s): 1189 - 1195
    Save to Project icon | PDF file iconPDF (813 KB)  

    This article presents a simple alternative procedure for evaluating the structure of InGaAs/InGaAs strained layer superlattices (SLSs) by x‐ray diffraction measurements. A symmetric reflection configuration is adopted for the scanning mode of (hkl) reflection measurement contrasting to the commonly used asymmetric configuration for SLS. In order to determine the average lattice constants for the SLS under the scanning mode, an analytical formula is derived with respect to the symmetric reflection configuration. A new discrimination method of the fundamental peak is also proposed in which a simple experimental method is useful especially for the SLS case because the fundamental peak is usually not the most intense. This method works also as a simple criterion of coherent lattice deformation. The analytical procedure is applied to the evaluation of InGaAs/InGaAs SLS structures. The lattice deformation and composition of well and barrier layers are estimated by parameter fitting to the satellite peak intensity profile based on the obtained average lattice constant. The results reveal that the sample is coherently deformed as designed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Elastic analysis of screw dislocations and two collinear cracks of different length

    Page(s): 1196 - 1203
    Save to Project icon | PDF file iconPDF (773 KB)  

    The elastic interaction between screw dislocations and two collinear internal cracks of different length has been investigated by the dislocation modeling method. The dislocation distribution to simulate the cracks and the stress field are obtained. From the stress field, the stress intensity factor at the crack tip and the image force on the dislocation have been derived. The dislocations inside the crack also play an important role in fracture. Newton’s third law is satisfied in this system. Finally, three special cases are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Investigation of optical damage mechanisms in hafnia and silica thin films using pairs of subnanosecond laser pulses with variable time delay

    Page(s): 1204 - 1208
    Save to Project icon | PDF file iconPDF (782 KB)  

    Optical damage thresholds of submicron‐thick, electron beam deposited HfO2 and SiO2 films on BK‐7 substrates have been measured by monitoring the emission of neutral constituents during excitation with time‐delayed pairs of 70‐ps laser pulses at a wavelength of 1064 nm. The dependence of the optical damage threshold on time delay provides evidence of the optical damage mechanism. For SiO2, linear absorption is the mechanism for energy deposition into the films by the laser beams. The data for HfO2 are less definitive, although linear absorption is the most likely damage mechanism. The behavior of the single‐layer films is compared to multilayer HfO2‐SiO2 high‐reflector coatings, for which a ‘‘conditioning’’ effect causes an increased optical damage threshold due to multiple pulse laser excitation at fluences below the single‐pulse optical damage threshold. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Defect‐property correlations in garnet crystals. VI. The electrical conductivity, defect structure, and optical properties of luminescent calcium and cerium‐doped yttrium aluminum garnet

    Page(s): 1209 - 1214
    Save to Project icon | PDF file iconPDF (701 KB)  

    The electrical and optical properties of calcium and cerium‐doped yttrium aluminum garnet (Ca,Ce:YAG) have been studied. Ca,Ce:YAG is a mixed ionic and electronic conductor with an ionic conductivity activation energy of 4.3 eV. Evidence of cluster formation with a consequent higher‐than‐expected activation energy is presented. The cerium normally enters the crystal as Ce+4, but it may be converted to Ce+3 under reducing atmospheres at elevated temperatures. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Transient boron diffusion in medium dose germanium‐implanted silicon

    Page(s): 1215 - 1218
    Save to Project icon | PDF file iconPDF (457 KB)  

    The transient enhanced diffusion of implanted boron has been examined by secondary ion mass spectrometry in crystalline silicon, in germanium preamorphized silicon, and in germanium amorphized and epitaxially regrown material. The total germanium dose used for amorphization of the silicon crystal was 1.2×1015 ions/cm2. The transient enhanced diffusion in regrown material was merely one‐third of the diffusion in original crystalline silicon while the enhanced diffusion in preamorphized silicon had been retarded to 70% of the crystalline silicon value. This shows that a medium germanium implantation dose is sufficient to reduce the depth of the boron doping profile during furnace high‐temperature annealing. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Growth of Pnp heterojunction bipolar transistor structures by metalorganic molecular beam epitaxy

    Page(s): 1219 - 1223
    Save to Project icon | PDF file iconPDF (497 KB)  

    Fabrication of high‐quality Pnp heterojunction bipolar transistors has traditionally been difficult due to the inability to achieve and confine high p‐ and n‐type doping levels using common dopants such as Be and Si. In this paper we discuss how carbon and tin can be incorporated during growth by metalorganic molecular beam epitaxy in order to produce Pnp structures. In particular it has been found that carbon introduced from trimethylgallium can be used to produce abrupt, thermally stable profiles in AlGaAs and that incorporation at concentrations up to mid‐1019 cm-3 does not adversely affect the optical or structural quality of the material. In addition, we have found that the use of tetraethyltin (TESn) for tin doping of the GaAs base layer allows for higher doping and better confinement of the dopant than can be obtained with elemental Sn. Consequently, large‐area (90‐μm diameter) Pnp transistors fabricated from material grown with TESn show higher gain than those grown with elemental tin, in spite of the higher base dopant concentration. The gain obtained with TESn, 45, is the highest yet reported for an abrupt‐junction, uniformly‐doped Pnp structure. Furthermore, because of the low parasitic resistances which result from the use of carbon and tin doping, the I–V characteristics obtained in this study show superior performance relative to previously published reports.   View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • In situ and ex situ structural characterization of β‐FeSi2 films epitaxially grown on Si(111)

    Page(s): 1224 - 1228
    Save to Project icon | PDF file iconPDF (675 KB)  

    The structural properties of β‐FeSi2 films grown on Si(111) are studied by means of several techniques. The films were grown in ultrahigh vacuum by solid phase epitaxy. The as‐deposited Fe films were studied in situ by low energy electron diffraction (LEED) and Auger spectroscopy. Fe thicknesses were calibrated by Rutherford backscattering. The behavior of the FeMVV/SiLVV Auger peaks ratio intensity as a function of Fe thickness indicates a Stranski–Krastanov mode of growth. Annealing of the Fe layers at temperatures between 400 and 600 °C led to the β‐FeSi2 formation. Sharp LEED patterns typical of the β‐FeSi2 orthorhombic structure were obtained. X‐ray double‐crystal diffraction was carried out on a film about 200 Å thick in order to determine the lattice mismatch between the β‐FeSi2 and the Si(111) planes accurately. The measured value of (2.1±0.1)×10-2 unambiguously indicates that (101) epitaxy takes place only on Si(111). No elastic strain of the overlayer was evident. The full width at half maximum of the overlayer diffraction peak indicates a good crystalline quality. An upper limit for mosaic spread was determined to be about 0.05°. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Molecular dynamic study of grain boundary embrittlement for [101] tilt copper bicrystals induced by bismuth segregation

    Page(s): 1229 - 1236
    Save to Project icon | PDF file iconPDF (1033 KB)  

    The selective bismuth segregation and the microprocess of fracture for the three [101] tilt copper bicrystals Σ9(2¯1¯2) 38.94°, Σ11(3¯2¯3) 50.48°, and Σ33(5¯4¯5) 58.99° have been studied by a molecular dynamics technique. The results show that the Bi segregation and the fracture behavior of the Cu‐Bi bicrystals are strongly dependent on the grain boundary (GB) structure. The Bi segregation is strongly related to the polyhedra constructing the GB cores and the stress fields of the GB dislocations (GBDs), and the GB embrittlement of copper induced by the Bi segregation is determined by the segregated concentration and the distribution of Bi atoms. With the increase of the relative number of pentagonal bipyramids and the localization of the stress fields of the GBDs in the GBs, the bicrystals Σ9, Σ11, and Σ33 show a decreasing propensity for the Bi segregation and subsequent different fracture behaviors. The severe intergranular brittle fracture that happens in the Σ9 bicrystal is mainly caused by the breaking of weakened Cu‐Cu bonds, which is related to the highly concentrated Bi segregation at the GB core. In the case of the Σ11 bicrystal, the segregation of Bi atoms at the GB shows an inhomogeneous distribution characteristic, so that the fracture is intergranular but with a large amount of shear deformation. The transgranular fraction that appears in the Σ33 bicrystal is related to the low concentration of the Bi segregation and the dispersive distribution of the Bi atoms along the GB and in the grains. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Relationship between interfacial native oxide thickness and bonding temperature in directly bonded silicon wafer pairs

    Page(s): 1237 - 1241
    Save to Project icon | PDF file iconPDF (643 KB)  

    High‐resolution transmission electron microscopy was employed to observe the morphology of the interfacial native oxide layers in the bonding interfaces of Czochralski (CZ) and float‐zone (FZ) silicon pairs that were bonded at different temperatures. It is shown that the thickness of the interfacial native oxide layers decreases with increasing bonding temperature in the temperature range of 200 °C to 600 °C, and remains fairly constant in the range of 600 °C to 1200 °C in both CZ and FZ silicon wafer pairs. Three factors are proposed to interpret this phenomenon: bonding interface phase transition, variation of native oxide chemical structure, and relaxation of stress in native oxide. A different factor dominates the change in thickness of the interfacial oxide layers in a different temperature range. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

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

Full Aims & Scope

Meet Our Editors

Editor
P. James Viccaro
Argonne National Laboratory