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Journal of Applied Physics

Issue 11 • Date Jun 1992

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Displaying Results 1 - 25 of 82
  • Issue Table of Contents

    Page(s): toc1
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    Freely Available from IEEE
  • Quantitative emission microscopy

    Page(s): R23 - R41
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    Emission microscopy has now become established as an effective technique in terms of reliability physics of industrial semiconductors. This convenient method allows chip verification and failure analysis to be carried out in many applications. Besides this, emission microscopy provides a technique for use in device engineering and the optimization of test structures. The key to using this technique to permit a more sophisticated quantitative analysis lies in a unique assignment of the light emission to the defect mechanism. Since the corresponding phenomena are numerous and their details are not fully clarified in all cases, further investigation is still required before this technique can be used routinely in a quantitative rather than qualitative approach. Some quantitative aspects of emission microscopy with respect to fundamental studies will therefore be outlined in this article, and the applicability of such practical guidelines will be illustrated. This provides the fundamentals for a comprehensive evaluation of the potential applications and degree of informativeness of this advanced method of failure analysis. View full abstract»

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  • Representation of tails of periodic and infinite‐range signals: Towards a treatment for truncation

    Page(s): 5303 - 5309
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    Two types of signals are considered: infinite‐range signals and periodic signals. Tails of infinite‐range signals can be described with an asymptotic power series (having terms of the type x-n with n≥2). For tails of periodic signals an asymptotic series [having terms of the type sin-n(πx/p) with p=period and n≥2] is derived from the asymptotic power series for the infinite‐range signals using Poisson summation. It is shown that for practical purposes the tails of a signal can be described quite satisfactorily with only a few terms of the series. On this basis nonmeasurable parts of tails of both symmetric and asymmetric signals can be estimated reliably and thus the effects of the unavoidable signal truncation can be counteracted. View full abstract»

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  • Instabilities in annealed proton exchange waveguides in lithium tantalate

    Page(s): 5310 - 5317
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    The stability of annealed proton exchange waveguides and devices in LiTaO3 is examined by monitoring the output power ratio of passive directional couplers. This is shown to be an extremely sensitive technique for measuring waveguide stability. Mode propagation constants of planar waveguides and near‐field mode sizes and losses of channel waveguides are also measured as a function of time. Data from these measurements indicate that the refractive index profile is unstable and continuously evolves even for relatively long anneal times. The instabilities appear to lower the local change in the refractive index either through the room‐temperature migration of hydrogen or a change in the magnitude the refractive index increase due to the proton exchange. Assuming that the hydrogen concentration profile is stable, the decrease in the refractive index was estimated to be ≊10-3 over a period of 90 days. Although the instabilities were seen in all of the fabricated devices, only a small portion of the total fabrication parameter space was investigated. Therefore, it is possible that the instability may be avoided as in LiNbO3, by using dilute melts or even longer anneal times. View full abstract»

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  • Propagation of several waves in a nonlinear medium displaying an optical activity: Application to four‐wave mixing in Bi12(Ge;Si)O20 crystals

    Page(s): 5318 - 5322
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    A set of coupled‐wave equations relative to degenerate four‐wave mixing is derived and solved for optically active Bi12(Ge;Si)O20 cubic crystals. Nonlinear absorption is taken into account. Circular polarized waves are used. The calculated results concerning phase conjugation efficiency are compared to the experimental ones. View full abstract»

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  • AlGaAs diode laser blue shift resulting from fast neutron irradiation

    Page(s): 5323 - 5331
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    Six TJS (transverse junction stripe) AlGaAs diode lasers were exposed to fast neutrons with fluences ranging from 2×1012 to 3×1013 n/cm2, and their tuning, gain, and dispersion curves were measured. The tuning and gain curves of four lasers showed blue shifts of several meV at neutron fluences as low as 2×1012 n/cm2; the other two lasers never showed this blue shift. In addition, the lasers that displayed a blue shift also showed an increase in their threshold currents. None of the lasers exhibited any change in their dispersion curves. To explain the blue shift, it is hypothesized that neutron irradiation reduces the efficiency for lasing in the bandtail states of these devices, forcing lasing action to occur between states with greater energy separation. A model in which the reduced efficiency takes the form of a decrease in the transition matrix element is found to yield blue shifts of the correct order of magnitude. Though bandtail effects may also explain the difference in radiation sensitivity among the TJS lasers, at present the reason why only four of the six lasers blue shifted after neutron irradiation is not well understood. View full abstract»

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  • Effect of optical activity on higher‐order self‐diffraction in absorptive photorefractive medium: Transmission geometry for two‐wave mixing

    Page(s): 5332 - 5337
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    Interactions between optical beams incident upon and higher‐order self‐diffracted beam generated within an absorptive and optically active photorefractive crystal of 23 symmetry are investigated by solving a set of coupled differential equations. It is shown that, under favorable conditions, a significant amount of power may be transferred to the newly generated wave. Investigated are the effects of optical activity, thickness and absorption of the crystal, coupling constant, and off‐Bragg parameter on energy transfer to the higher‐order diffracted beam. Coupled wave equations are solved numerically by a fourth‐order Runge–Kutta method and results are presented in graphical form. The analysis is valid only for the near collinear interacting beams, i.e., in the limit of large grating spacing. View full abstract»

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  • Magnetic field enhanced performance of a copper hollow anode cathode laser

    Page(s): 5338 - 5343
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    The output beam power and small‐signal unsaturated gain on the He‐Cu 780.8 nm transition in a hollow slotted‐anode cathode laser are increased significantly by the application of a longitudinal magnetic field and each shows a marked dependence on the field in the range 10 to 40 mT. The laser output power and the gain increase with the discharge current, while the optimum magnetic field (∼22 mT) results in a further significant increase both in output power and gain. These effects have their origin in the transverse deflection of the beam electrons by the magnetic field. View full abstract»

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  • Longitudinal mode stability difference in Se‐ and Si‐doped AlGaAs lasers

    Page(s): 5344 - 5346
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    The longitudinal mode behavior of AlGaAs lasers with n‐type cladding layers doped with Se and Si is reported. The longitudinal mode of the lasers with highly Se‐doped cladding layer is stabilized, and large hysteresis of mode jump is observed as temperature changes. In the case of highly Si‐doped cladding layers, however, the mode hops to the adjacent one and no hysteresis is observed. These phenomena are explained by the difference in thermal activation energy between Se‐ and Si‐related DX centers. View full abstract»

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  • Gain measurements of high‐pressure ultraviolet‐preionized self‐sustained discharge pumped atomic xenon laser

    Page(s): 5347 - 5352
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    To explore the laser kinetics of atomic xenon lasers pumped by an ultraviolet‐preionized, self‐sustained discharge, time‐resolved small‐signal gains are measured using a long‐pulse probe laser. Faster electron mixing processes among excited xenon manifolds in the 6p state may affect the small‐signal gain distribution among 1.73, 2.03, and 2.65 μm laser lines, which share the same upper laser level Xe(5d[3/2]1) at excitation rates in excess of 160 kW/cm3. When the excitation rate in a late part of the discharge is increased, absorption caused by repumping of the lower laser level is observed at 1.73 μm. The measured gains are discussed in conjunction with multiline laser oscillation performance obtained by the same laser device. View full abstract»

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  • Anisotropic thermal conductivity in chemical vapor deposition diamond

    Page(s): 5353 - 5356
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    The thermal conductivity of thick‐film diamond prepared by chemical vapor deposition (CVD) has been measured with heat flowing in a direction perpendicular to the plane of the film. A laser flash technique with fast infrared detection has been devised for measurement of thin samples with high conductivity. The conductivity perpendicular to the plane is observed to be at least 50% greater than with heat flowing parallel to the plane. This anisotropy is attributed to low‐quality grain boundaries in the columnar microstructure. The observed dependence of the thermal conductivity on microstructure has important implications for thermal management of microelectronic devices with CVD diamond. View full abstract»

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  • Two‐dimensional inverse heat conduction problem of estimating the time‐varying strength of a line heat source

    Page(s): 5357 - 5362
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    Inverse analysis utilizing the conjugate gradient method is used to estimate the timewise varying strength of a line heat source placed at a specified location in a rectangular region with insulated boundaries. No prior information was used on the functional form of the source strength with time. Transient temperature recordings taken at the boundaries of the region served as the simulated experimental data needed as input for the inverse analysis. In order to test the accuracy of the inverse analysis under most strict conditions, timewise variation of the source strength is chosen in the form of rectangular, triangular, and sinusoidal functions. Both the regular iterated and modified conjugate gradient method are used for solving the inverse problem. The modified conjugate gradient method often provided the answer with smaller number of iterations when the initial condition for the unknown function was available. View full abstract»

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  • Longitudinal electron diffusion coefficients in gases: Noble gases

    Page(s): 5363 - 5371
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    Values of the ratio of the longitudinal diffusion coefficient to mobility DL/μ for electrons in He, Ar, Kr, and Xe are derived from current waveforms obtained during earlier measurements of electron mobility. The electric field to gas density ratios E/N cover the wide range of 10-3 to 20 Td, thereby bridging previous experiments at low E/N to recent experiments at high E/N. Here 1 Td=1×10-21 V m2. The corresponding DL/μ values range from 0.0066 eV for thermal electrons at 77 K to 10 eV. In addition to the well‐known peak in DL/μ for Ar at E/N between 0.01 and 0.1 Td caused by the Ramsauer minimum in the momentum transfer cross section, we find previously unreported low‐energy peaks in DL/μ vs E/N in Kr and Xe and previously unreported pronounced leveling‐off in DL/μ at E/N≳8 Td in Ar, Kr, and Xe. Calculations of transport coefficients using numerical solutions of the Boltzmann equation and cross section sets in the literature give good agreement with experiment from E/N producing thermal electrons up to average energies ≊10 eV and E/N up to 100 Td, the upper limit of our calculations. The leveling off of DL/μ at high E/N is caused by inelastic collisions. View full abstract»

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  • Mass spectroscopic study of CH3 radicals produced in a hollow cathode discharge cell

    Page(s): 5372 - 5375
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    Neutral CH3 radicals in a hollow cathode discharge cell containing methane have been detected with a quadrupole mass spectrometer, using the threshold ionization technique. With the experimental conditions employed in this work the measured efficiency in CH3 production has been 0.2%, which is higher than that shown for other types of discharges in the bibliography. On the other hand a high depletion of the CH4 density has been observed and the mass spectrum of the discharge shows the appearance of compounds at m=25, 26, and 27, proceeding from recombination processes. View full abstract»

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  • Frequency up‐conversion of a high‐power microwave pulse propagating in a self‐generated plasma

    Page(s): 5376 - 5380
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    In the study of the propagation of a high‐power microwave pulse, one of the main concerns is how to minimize the energy loss of the pulse before reaching the destination. In the very high‐power region, one has to prevent the cutoff reflection caused by the excessive ionization in the background air. A frequency autoconversion process that can lead to reflectionless propagation of powerful electromagnetic pulses in self‐generated plasmas is studied. The theory shows that under the proper condition the carrier frequency ω of the pulse shifts upward during the growth of local plasma frequency ωpe. Thus, the self‐generated plasma remains underdense to the pulse. A chamber experiment to demonstrate the frequency autoconversion during the pulse propagation through the self‐generated plasma is conducted. The detected frequency shift is compared with the theoretical result calculated by using the measured electron density distribution along the propagation path of the pulse. Good agreement is obtained. View full abstract»

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  • Resonator amplification of microwave emission from a relativistic beam‐plasma system

    Page(s): 5381 - 5385
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    Electromagnetic emission produced by a propagating electron beam in a cylindrical drift chamber can be amplified by axially reflecting screens. Radiation appears at the first and second plasma harmonics with linewidths ∼0.1 νp. Amplification scales with νp2 and lags electron‐beam voltage by several hundred nanoseconds, implying that electrostatic waves moving at the electron thermal speed must traverse the resonator before amplification begins. Rotating the reflectors beyond 30° lessens amplification, suggesting a broad reflection property. View full abstract»

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  • The formation and annealing of dislocation damage from high‐dose self‐ion implantation of aluminum

    Page(s): 5386 - 5390
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    Quantitative electron channeling and weak‐beam transmission electron microscopy (TEM) measurements of dislocation density have been used to study the formation and annealing of the dislocation network in self‐ion‐implanted aluminum. The channeling linewidth is found to be proportional to the dislocation density. Several mathematical expressions for the dislocation network growth are examined. One by Igata et al. [in Effects of Radiation on Materials: Proceedings of the 10th International Symposium, edited by D. Kramer, H. R. Brager, and J. S. Perrin, STP 725 (ASTM, Philadelphia, 1980), p. 627] is found to describe the implantation data accurately. This model has a linear growth term and terms for dislocation loss due to surface effects and recovery. The fit is insensitive to the relative importance of the two loss terms. Annealing is found to occur in two stages; roughly one third of the dislocation density is gone by 300 °C, corresponding to typical recovery processes, while the remaining network is stable to about 500 °C. View full abstract»

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  • Calorimetric measurements of the thermal relaxation in nanocrystalline platinum

    Page(s): 5391 - 5394
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    The enthalpy release during the heating of nanocrystalline platinum samples has been measured and at least two different contributions to the excess Gibbs free energy have been identified by controlling the grain size. About one half of the excess enthalpy is released during a first relaxation process without any measurable variation of grain size followed by a second relaxation which can be attributed to grain growth. The isothermal heat release of the grain growth is analyzed to calculate the excess grain boundary enthalpy. View full abstract»

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  • Bonding properties of glow‐discharge polycrystalline and amorphous Si‐C films studied by x‐ray diffraction and x‐ray photoelectron spectroscopy

    Page(s): 5395 - 5400
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    Polycrystalline and amorphous Si‐C films were prepared by rf glow‐discharge decomposition of silane‐methane mixtures at 700 °C. We have demonstrated that polycrystalline SiC films with large grains grow under heavy hydrogen dilution. The bonding properties as a function of film composition and hydrogen dilution were characterized by means of x‐ray diffraction and x‐ray photoelectron spectroscopy. Crystallization takes place at around C content x=0.5 in Si1-xCx, accompanying some segregation of carbon atoms in grain boundaries, as a result of a preference for heteronuclear bonds. It was shown that C‐C(C3-nSin) (n=0–3) bonds appear in the carbidic phase of C‐rich films, leading to occurrence of compressive strain in the crystalline SiC grains. In addition, effects of hydrogen dilution were discussed in correlation with the strain. View full abstract»

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  • Scanning tunneling microscope‐promoted growth of nanometer‐scale, uniform gold stripes on reconstructed Au(111) surfaces

    Page(s): 5401 - 5409
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    Scanning the scanning tunneling microscopy (STM) tip on a Au(111) (22±1)×√3 reconstructed surface causes monatomic stripes to grow preferentially on the fcc portions of the surface. Stripes several 100 nm’s in length, ∼4 nm wide, and separated by spaces ranging from 2 to ∼4 nm (the hcp regions of the reconstructed surface) can be grown. Stripe formation only takes place when the scan direction corresponds, more or less, with the [1,1,-2] primary direction of the reconstruction. Growth occurs much more rapidly than can be accounted for by diffusion alone, leading to the conclusion that the STM tip transports gold, previously picked up from other portions of the surface, to the growing ends of the stripes. Stripes grown in this way may serve as convenient templates for subsequent growth of quantum wire structures by molecular beam epitaxy. View full abstract»

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  • Molecular‐dynamics simulations of bulk and surface damage production in low‐energy Cu→Cu bombardment

    Page(s): 5410 - 5418
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    Molecular‐dynamics simulations are employed to study in detail the effects of low‐energy (≤100 eV) bombardment of a Cu (001) surface by Cu atoms. By following the simulation up to 4 ps in real time, the end configuration of defects in the target can be observed. We present results on the vacancy and interstitial distribution in the target, the spontaneous defect recombination, the number of surface vacancies and adatoms produced, and the mixing of target atoms induced by the bombardment. Furthermore, the fate of the projectile atom-backscattering and implantation-and the sputtering behavior are investigated. The relevance of the results on the modelling of ion‐beam (assisted) deposition is discussed. View full abstract»

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  • Thermally stimulated current of Si‐ion‐implanted GaAs

    Page(s): 5419 - 5422
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    A thermally stimulated current technique has been carried out to investigate the defect levels in Si‐ion‐implanted GaAs. Thermally stimulated current measurements have been performed in the temperature range of 90–300 K, and five deep traps with activation energies of 0.18, 0.20, 0.31, 0.40, and 0.43 eV have been observed. It is considered that the one of the traps (Ea=0.18 eV) shows the optical quenching effect and another trap (Ea=0.20 eV) is related to the damage due to the implanted ions. View full abstract»

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  • Recrystallization behavior of silicon implanted with iron

    Page(s): 5423 - 5426
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    The solid phase epitaxial growth (SPEG) of amorphized Si layers implanted with Fe (1×1015 cm-2, 100 keV) was investigated in the temperature range from 500 to 550 °C using Rutherford backscattering spectrometry. The push‐out of Fe atoms by the moving amorphous‐crystalline (a‐c) interface was observed during annealing, and enhancement of the recrystallization rate was induced by the presence of Fe. These results are discussed in terms of a model that assumes that Fe atoms are trapped in the amorphous layer and released when they are reached by the moving a‐c interface during the SPEG process. View full abstract»

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  • Structure and crystallization of low‐pressure chemical vapor deposited silicon films using Si2H6 gas

    Page(s): 5427 - 5432
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    Microstructures of silicon films deposited on SiO2 substrates by low‐pressure chemical vapor deposition using Si2H6 gas were investigated and compared to those using conventional SiH4 gas by transmission electron microscopy and x‐ray diffraction. The deposition rate of the Si2H6 process was about ten times higher than that of SiH4 process at low temperatures (≪550 °C). The transition deposition temperature from amorphous to polycrystalline film was found to be around 580 °C, which was similar to that of the SiH4 process. The film deposited at 600 °C was partially crystalline and had equi‐axed grains with the largest average grain size of 0.3 μm while the films using SiH4 has needle‐like columnar grains with smaller sizes (200 Å). The x‐ray diffraction analysis showed that the structural disorder to amorphously deposited Si films increases as deposition temperature decreases. The grain size in the film after crystallization at 600 °C strongly depended on the deposition temperature and the deposition rate, producing a larger grain size at a lower deposition temperature and/or at a higher deposition rate (Si2H6 deposition compared to SiH4 deposition). The apparent increase in grain size can be explained as a result of the lowered number of crystal nuclei due to a decrease in the number of pre‐existing microcrystallites serving as heterogeneous nucleation seeds. When the deposition rate was lower than the critical value (approximately 2–4 nm/min), the grain size in the crystallized film decreased for both SiH4 and Si2H6 films. The maximum grain sizes were 4.5 and 0.3 μm at the deposition temperatures of 485 and 550 °C for the films using Si2H6 and SiH4 gases, respectively. View full abstract»

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  • Tantalum as a diffusion barrier between copper and silicon: Failure mechanism and effect of nitrogen additions

    Page(s): 5433 - 5444
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    The interaction of Cu with Si separated by thin (50 nm) layers of tantalum, Ta2N, and a nitrogen alloy of Ta has been investigated to determine the factors that affect the success of these materials as diffusion barriers to copper. Intermixing in these films was followed as a function of annealing temperature by in situ resistance measurements, Rutherford backscattering spectra, scanning electron microscopy, and cross‐section transmission electron microscopy. Ta prevents Cu‐silicon interaction up to 550 °C for 30 min in flowing purified He. At higher temperatures, copper penetration results in the formation of η‘‐Cu3Si precipitates at the Ta‐Si interface. Local defect sites appear on the surface of the sample in the early stages of this reaction. The Ta subsequently reacts with the substrate at 650 °C to form a planar hexagonal‐TaSi2 layer. Ta silicide formation, which does not occur until 700 °C in a Ta‐Si binary reaction couple, is accelerated by the presence of Cu. Nitrogen‐alloyed Ta is a very similar diffusion barrier to Ta. It was found that Ta2N is a more effective barrier to copper penetration, preventing Cu reaction with the substrate for temperatures up to at least 650 °C for 30 min. In this case, local Cu‐Si reaction occurs along with the formation of a uniform Ta5Si3 layer at the Ta2N‐Si interface. View full abstract»

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Aims & Scope

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

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Editor
P. James Viccaro
Argonne National Laboratory