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1 Dec 1958

Volume 29, Issue 12, pp. 1627-1774

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Calculations on the Shape and Extent of Space Charge Regions in Semiconductor Surfaces

G. C. Dousmanis and R. C. Duncan

J. Appl. Phys. 29, 1627 (1958); http://dx.doi.org/10.1063/1.1723012 (3 pages) | Cited 19 times

Online Publication Date: 15 June 2004

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The shape and extent of space charge regions in semiconductor surfaces are briefly discussed. Curves describing the potential as a function of distance inside the semiconductor are obtained by numerical integration of the Poisson equation. The curves apply to all semiconductors. They show the effects of different resistivities and the increased depth of the space charge regions expected in pure III‐V compounds over those encountered in Ge and Si.

Effect of Proton Irradiation Upon Hydrogen Reduction of NiO

M. T. Simnad, R. Smoluchowski, and Aija Spilners

J. Appl. Phys. 29, 1630 (1958); http://dx.doi.org/10.1063/1.1723013 (3 pages) | Cited 3 times

Online Publication Date: 15 June 2004

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It is shown that the reduction of a metal oxide such as nickel oxide by hydrogen gas is strongly influenced by nuclear irradiation. The initial induction period is shortened and the subsequent reduction accelerated. The effects anneal out at higher temperatures. A probable mechanism of this acceleration is suggested.

Effect of Torsional Stress on the Electrode Potential of Copper

Ken Nobe and William F. Seyer

J. Appl. Phys. 29, 1632 (1958); http://dx.doi.org/10.1063/1.1723014 (3 pages) | Cited 1 time

Online Publication Date: 15 June 2004

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The emf of a galvanic cell which consisted of a stressed metal electrode and an unstressed metal electrode was measured. The experimental data showed that for low torsional stresses there was a parabolic relationship between the emf and the torsional stress.
It was observed that the stressed electrode was more anodic with respect to the unstressed reference electrode in agreement with the majority of the previous investigations.
Experimental data of emf and torsional stresses for B & S gauge 12, 14, and 16 hard‐drawn copper wires are presented.

Revealing Dislocation Sites in Aluminum by Transmission Electron Microscopy

D. L. Robinson

J. Appl. Phys. 29, 1635 (1958); http://dx.doi.org/10.1063/1.1723015 (5 pages) | Cited 1 time

Online Publication Date: 15 June 2004

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The occurrence of dislocation sites along grain boundaries is shown by transmission electron microscopy. Small thin sections of aluminum for these studies were obtained by electrolytic oxidation, with subsequent dissolution of the oxide. Dislocation sites along grain fragments in cold worked aluminum have been observed which, by Cottrell's formula, indicate grain orientation differences greater than 2° of arc. This method of examination makes possible the observation and analysis of dislocations in metals where boundaries are at other than extremely low angles of crystal misorientations. Also, it has been found useful for following the movement of dislocations within grains of the material and their migration to grain boundaries.

Dielectric Relaxation Spectra of Lithium Borosilicate Glasses

L. Heroux

J. Appl. Phys. 29, 1639 (1958); http://dx.doi.org/10.1063/1.1723016 (7 pages) | Cited 11 times

Online Publication Date: 15 June 2004

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The dielectric relaxation spectra of a system of lithium borosilicate glasses have been investigated over the frequency range 0.01 cps to 500 kc and temperatures between 25°–350°C. The spectra of the samples exhibit well‐defined peaks in the dielectric loss factor and dispersion in the dielectric constant. The activation energies associated both with the lithium ion mean relaxation frequency and the lithium ion dc conductivity (zero frequency conductivity) are constant with temperature; their difference for each sample appears to be an indication of the distribution of activation energies of the sample. The experimental data show that an analytical function proposed by K. W. Wagner adequately describes the distribution of relaxation times associated with the lithium ion relaxation process in the glass network. The distribution originates from a spread in activation energies for low lithium concentrations and a spread in the period of vibration of the lithium ions about their equilibrium position for higher concentrations.

Parametric Amplification of Space Charge Waves

A. Ashkin

J. Appl. Phys. 29, 1646 (1958); http://dx.doi.org/10.1063/1.1723017 (6 pages) | Cited 4 times

Online Publication Date: 15 June 2004

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By modulating a beam strongly with a high‐level signal, called the ``pump'' signal, a low‐level space charge wave of another frequency imposed on the beam can be parametrically amplified. With the pump frequency twice the signal frequency, 13‐db gain per plasma wavelength has been observed in a movable cavity experiment. Over a 10‐in. length of beam the signal has been observed to increase 41 db. When the imposed signal wave's frequency is not exactly half the pump frequency, the beam generates another wave called the ``idler'' such that ωsignal+ωidler=ωpump with both signal and idler growing exponentially with distance along the beam. In another experiment with the pump frequency lower than the signal frequency, the signal was observed to increase by 30 db over a 9.2 in. length of beam.

Generation of High‐Velocity Projectiles

Melvin A. Cook and Robert T. Keyes

J. Appl. Phys. 29, 1651 (1958); http://dx.doi.org/10.1063/1.1723018 (7 pages) | Cited 1 time

Online Publication Date: 15 June 2004

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A technique of controlling the shape of detonation wave fronts in high explosives by inert wave control inserts was applied to generate discrete ultrahigh‐velocity pellets. Tests to determine the most suitable pellet shape as well as the optimum charge configuration are described, and velocities up to 7600 m∕sec were realized for 0.95‐g aluminum pellets. The mechanism whereby pellets are accelerated by ``shaped'' waves is discussed, and the conclusion is reached that a simple model based upon the transmission of shock from the detonation wave to the pellet is not applicable.

Dynamic Fatigue of Glass

R. J. Charles

J. Appl. Phys. 29, 1657 (1958); http://dx.doi.org/10.1063/1.1723019 (6 pages) | Cited 77 times

Online Publication Date: 15 June 2004

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An analytical model, which is applicable to static fatigue of lime glass, has been extended to account for dynamic fatigue of the same glass. The model successfully predicts the room temperature strain rate sensitivity of the failure process in lime glass and indicates a method by which the stress concentration relationship, applicable to microscopic flaws on glass surfaces, may be obtained by experiment. Resulting experiments showed that the stress concentration relationship proposed by Inglis is valid.

Arc Cathode Movement in a Magnetic Field

A. E. Guile and P. E. Secker

J. Appl. Phys. 29, 1662 (1958); http://dx.doi.org/10.1063/1.1723020 (6 pages) | Cited 11 times

Online Publication Date: 15 June 2004

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An arc cathode spot in a transverse magnetic field may move either in the Amperian (forward) direction, or in the opposite (retrograde) direction. Experiments are described which show that forward continuous motion is caused by magnetic fields at the cathode surface, as is the case with retrograde motion, and that both of these motions depend upon the material and surface condition of the cathode. Forward cathode velocity both when continuous and when moving in a stepping process is independent of arc current over a wide range.
The theories so far suggested for retrograde motion do not appear to be able to account for the dependence of retrograde cathode movement on the nature of the cathode surface.

Thermometric Study of the Frozen Products from the Nitrogen Microwave Discharge

B. J. Fontana

J. Appl. Phys. 29, 1668 (1958); http://dx.doi.org/10.1063/1.1723021 (6 pages) | Cited 12 times

Online Publication Date: 15 June 2004

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Thermometric observations have been made of the phenomena accompanying the stabilization and the recombination of free nitrogen atoms in a solid molecular nitrogen matrix at liquid helium temperatures. Condensation from the gas phase may occur at temperatures considerably above the 4.2°K coolant temperature as the result of the normal change in heat content and the heat of atom recombination. Estimates, made from the latter effects, of the free atom concentration in the gas phase were as high as 4 atom %. Qualitative confirmation of the presence of an energetic species stabilized in the solid phase was made by detection of heat release upon warmup. From the latter effect a minimum nitrogen atom concentration in the solid of 0.03 atom % was estimated. For the conditions used the initiation of atom recombination occurs at a temperature of about 9°K. The upper limit of about 36°K for stabilization coincides with the known thermal transition in solid nitrogen. The data suggest that at least above 9°K diffusion of nitrogen atoms occurs throughout the solid matrix during deposition from the gas phase. If recombination during warmup is diffusion‐controlled, unusual dependence upon temperature is indicated.

Analysis of the Emissive Phase of a Pulsed Maser

H. H. Theissing, F. A. Dieter, and P. J. Caplan

J. Appl. Phys. 29, 1673 (1958); http://dx.doi.org/10.1063/1.1723022 (6 pages)

Online Publication Date: 15 June 2004

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The operation of a pulsed solid‐state Maser consists essentially of alternate periods of spin inversion and stimulated spin emission. Inversion can be accomplished by a short driving pulse or an adiabatic rapid passage. In the emission phase a weak signal field causes the spin system to spiral back coherently and radiate. The emissive phase can be treated by equations which for finite relaxation times can not be solved in closed form, but which are amenable to machine computation. Such numerical solutions giving the transverse moment, output field, output power, and power gain as a function of time were computed for various relaxation times, input fields, and values of the oscillation parameter. The results are interpreted with respect to applications of both regenerative and superregenerative modes of operation.

Production of Dislocations in Germanium by Thermal Shock

R. S. Wagner

J. Appl. Phys. 29, 1679 (1958); http://dx.doi.org/10.1063/1.1723023 (4 pages) | Cited 9 times

Online Publication Date: 15 June 2004

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Dislocations introduced into single crystals of germanium grown by the Czochralski technique have been studied. It was found that most of the dislocations do not originate during growth, but are produced after growth as a result of thermal shock. Thermal stresses resulting from nonuniform temperature gradients during growth seem to have little or no effect on the dislocation density and distribution.

Comparison between the Linear and Nonlinear Steady‐State Behavior of a Heated Tube

B. L. McFarland

J. Appl. Phys. 29, 1682 (1958); http://dx.doi.org/10.1063/1.1723024 (3 pages)

Online Publication Date: 15 June 2004

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The range of applicability for the solution of the linearized diffusion equation is discussed for a particular case—heating of a homogeneous tube by internal energy generation. The range is defined by comparisons of series solutions of the linear and nonlinear diffusion equations (constant material properties vs variable material properties). Two sources of errors in the constant‐property solution are evaluated and a criterion for the limits of applicability of the linear solution is derived.

Dislocation Model of Low‐Temperature Creep

J. Weertman

J. Appl. Phys. 29, 1685 (1958); http://dx.doi.org/10.1063/1.1723025 (5 pages) | Cited 23 times

Online Publication Date: 15 June 2004

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A low‐temperature dislocation creep model of the exhaustion type is proposed to account for the temperature independent activation energies which are found in recent experiments. Logarithmic creep can be obtained from the model if a Gaussian distribution function of Frank‐Read sources is assumed. The theory is applicable under easy glide conditions but should not be used when extensive double glide occurs. The theory can be extended into the liquid helium temperature range with the aid of Glen‐Mott quantum‐mechanical dislocation tunneling.

Magnetostriction of Low‐Density Cobalt Rondel

H. E. Stauss

J. Appl. Phys. 29, 1690 (1958); http://dx.doi.org/10.1063/1.1723026 (2 pages)

Online Publication Date: 15 June 2004

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A dimensional change that simulates magnetostriction can be expected when a porous or spongy ferromagnetic body is placed in a magnetic field. Such an effect has been observed. Polycrystalline cobalt with a density less than 50% of normal developed a strain of −139×10−6, whereas cobalt of normal density developed a strain of −28×10−6. This finding appears to open the way for the development of materials with enhanced values of strain in a magnetic field.

Microwave Faraday Rotation: Design and Analysis of a Bimodal Cavity

A. M. Portis and Dale Teaney

J. Appl. Phys. 29, 1692 (1958); http://dx.doi.org/10.1063/1.1723027 (7 pages) | Cited 37 times

Online Publication Date: 15 June 2004

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The design and analysis of a bimodal cavity for the observation of microwave Faraday rotation is presented. An equivalent circuit of lumped elements is developed and the coupling between degenerate cavity modes is expressed in terms of the elements of the susceptibility tensor of the material producing the rotation. The theory is checked against experimental results with a paramagnetic salt and substantial agreement is obtained. A cavity of this type when used in conjunction with superheterodyne detection appears to provide a high sensitivity spectrometer for the observation of magnetic resonance.

Shape Distribution of Magnetic Powders

Clark E. Johnson and William Fuller Brown

J. Appl. Phys. 29, 1699 (1958); http://dx.doi.org/10.1063/1.1723028 (3 pages) | Cited 17 times

Online Publication Date: 15 June 2004

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See Also: Erratum

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In work reported earlier, the average length‐to‐diameter ratios determined magnetically did not agree with those observed under the electron microscope; this was thought due to magnetic interactions. This paper describes further shape determination measurements on γ‐Fe2O3 samples of increasing dilution by the original method and by two analogous methods described by Wohlfarth. The results show a slight increase of mean length‐to‐diameter ratio with dilution and a considerable broadening of the distribution toward large length‐to‐diameter ratios. The different methods of measurement described do not yield the expected congruent curves at very low concentration. This indicates a deviation from Stoner‐Wohlfarth rotation in these particles. The details of the mathematical methods are also described.

Noise in Oxide Cathode Coatings

H. J. Hannam and A. Van Der Ziel

J. Appl. Phys. 29, 1702 (1958); http://dx.doi.org/10.1063/1.1723029 (4 pages) | Cited 1 time

Online Publication Date: 15 June 2004

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Noise measurements have been performed on oxide‐coated cathodes at frequencies of 8 Mc and of 30 cycles. At 8 Mc, where thermal noise and shot noise predominate, the measurements show thermal noise at high cathode temperatures (pore conduction region) and at low cathode temperatures (grain conduction region) with a pronounced noise peak caused by shot noise in the temperature range where pore conduction switches over to grain conduction.
Noise measurements at 30 cycles where flicker noise (with a 1∕f noise spectrum) predominates, indicate that the pore noise corresponds to the flicker noise expected for a semiconductor with a voltage‐independent conductivity, whereas the grain noise corresponds to the flicker noise expected for a semiconductor with voltage‐dependent conductivity. The measurements also show that the pores are inherently noisier than the grains at low frequencies. The results agree with a qualitative theoretical analysis.

Electrophotoluminescent Amplification

R. E. Halsted

J. Appl. Phys. 29, 1706 (1958); http://dx.doi.org/10.1063/1.1723030 (3 pages) | Cited 1 time

Online Publication Date: 15 June 2004

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Alternating electric fields can modify the time distribution of luminescent recombination in sulfide‐type phosphors with the expenditure of less electrical energy than is contained in the fluctuating component of the emitted visible radiation. Within the range of excitation and electrical signal input conditions where this is true, the phosphor sample may be regarded as an amplifier deriving its power from incident radiation, which can convert an applied electrical signal into an output light signal with energy gain and frequency fidelity.

Modified Rotational Model of Flux Reversal

E. M. Gyorgy

J. Appl. Phys. 29, 1709 (1958); http://dx.doi.org/10.1063/1.1723031 (4 pages) | Cited 10 times

Online Publication Date: 15 June 2004

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A nonuniform magnetic configuration for rapid rotational flux reversal in square‐loop ferrite cores is analyzed. It is shown that the demagnetizing effects due to the boundary of the toroid are, to a good approximation, negligible for toroids with cross‐sectional radii as small as 2.5×10−2 cm. A basic assumption of an earlier rotational model of flux reversal was that these demagnetizing fields could be neglected. The predictions of this modified model at high drives are similar to those of the earlier model. The possibility of correlating Hc (the intercept of the extrapolated linear region of the inverse switching time versus drive field plot) with more basic parameters through a model of this type is indicated.

Radiation Enhanced Diffusion in Solids

G. J. Dienes and A. C. Damask

J. Appl. Phys. 29, 1713 (1958); http://dx.doi.org/10.1063/1.1723032 (9 pages) | Cited 169 times

Online Publication Date: 15 June 2004

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A simple theory of radiation enhanced diffusion has been worked out which describes the dependence of this enhancement on flux and temperature under steady‐state conditions. The theoretical study also shows that the measurement of enhanced diffusion as a function of temperature can indicate the mechanism by which defects are removed from the lattice. Alpha‐brass was chosen for the experimental work because it is a kinetically simple system, not complicated by nucleation, in which diffusion is easily followed by measuring the electrical resistivity changes associated with changes in short‐range order. The enhanced diffusion rate during irradiation in the Brookhaven reactor has been measured in this alloy at several temperatures in the range 0 to 190°C. This enhancement is independent of temperature from 0 to 150°C, in excellent agreement with the theoretical predictions for the case where the radiation induced defects finally disappear at internal surfaces. Some implications of radiation enhanced diffusion and suggestions for further study are also discussed.

Radiation‐Induced Recombination Centers in Germanium

O. L. Curtis, J. W. Cleland, and J. H. Crawford

J. Appl. Phys. 29, 1722 (1958); http://dx.doi.org/10.1063/1.1723033 (8 pages) | Cited 12 times

Online Publication Date: 15 June 2004

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An attempt has been made to provide a better understanding of minority carrier recombination processes in irradiated germanium. To this end, studies have been made of the minority carrier lifetime of both n‐ and p‐type material, following fast neutron and Co60 γ irradiations. The effect of carrier concentration and temperature has been determined. The primary conclusion drawn from these investigations is that the recombination process is associated with an energy level located 0.20 ev below the bottom of the conduction band. From measurements of the lifetime in n‐type specimens, the hole capture cross section has been calculated and found to be σp=3×10−15 cm2 and σp=4×10−16 cm2 for neutron and γ‐induced centers, respectively. If a second, lower lying level is associated with the second ionization of the defect responsible for recombination, then the effective number of recombination centers is reduced in p‐type material as the Fermi level approaches the valence band, due to this ionization. Such a process is in qualitative agreement with the observed data.

Photoconductive Response of Single Crystal Germanium Layers Prepared by the Pyrolytic Decomposition of GeI2

Donald C. Cronemeyer

J. Appl. Phys. 29, 1730 (1958); http://dx.doi.org/10.1063/1.1723034 (6 pages) | Cited 3 times

Online Publication Date: 15 June 2004

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Layers of single crystal germanium have been prepared by pyrolytic decomposition of GeI2 at about 350°C upon single crystal seeds of germanium by J. C. Marinace. The substrate germanium could be removed and the resultant thin layers (∼5×10−3 cm) studied. The Hall coefficient and resistivity measured on these layers by Dunlap et al. showed that the layers as grown were usually n type and contained about 1016 donors∕cm3. These donors are situated at 0.22±0.04 ev below the conduction band.
In the work reported here, the photoresponse of such layers at 77°K was found to extend to about 6 μ in substantial agreement with this thermal activation energy. The 0.2‐ev donors apparently can be annealed out by prolonged heating at 550°C. The layers could also be intentionally doped with standard acceptors such as Al during formation. It was hoped that it would be possible to obtain the incorporation of Au into the layers. For this purpose, layers for which Au doping was attempted were annealed to remove the 0.2‐ev donors. Although some of the layers became p type, a comparison of the photoresponse at 77°K with the photoresponse obtained for a 5×10−3 cm thick p‐type plate of regularly Au‐doped germanium showed no evidence for the 0.15 ev Au level. Likewise, annealed layers for which Ag doping was attempted were examined but yielded no positive identification of the 0.14‐ev level of Ag.

Effect of Statically Applied Stresses on the Velocity of Propagation of Ultrasonic Waves

R. H. Bergman and R. A. Shahbender

J. Appl. Phys. 29, 1736 (1958); http://dx.doi.org/10.1063/1.1723035 (3 pages) | Cited 20 times

Online Publication Date: 15 June 2004

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The paper gives the results of an experimental investigation of the changes in the velocities of ultrasonic waves propagating transverse to the direction of applied stress in an aluminum column. The ultrasonic modes considered are longitudinal waves, shear waves with particle motion along the direction of applied stress, and shear waves with particle motion transverse to the direction of applied stress. The experimental results indicate that the relevant elastic constant for longitudinal waves is independent of stress, while that for the shear waves is stress dependent and also depends on the relative orientation of the particle motion and the direction of applied stress.

On the Nature and Location of Bubble Nuclei in Boiling from Surfaces

S. G. Bankoff, A. J. Hajjar, and B. B. McGlothin

J. Appl. Phys. 29, 1739 (1958); http://dx.doi.org/10.1063/1.1723036 (3 pages) | Cited 7 times

Online Publication Date: 15 June 2004

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In the pool boiling of pure organic liquids from a reproducible platinum surface, an initial temperature overshoot is observed before the surface breaks into nucleate boiling. A logarithmic plot of heat flux vs temperature excess has a slope of 3.5 for the first traverse but subsequent traverses give a reproducible line having a higher slope and surface temperature. Vigorous heating in air restores the surface to its original condition. These results are explained in terms of the trapped‐bubble hypothesis by assuming that many potential vapor traps on the surface are filled with liquid initially, and fill with vapor once boiling commences. The gradual increase in surface temperature for a given flux is attributed to the progressive deaeration of the nucleating centers by dilution with vapor. To reconcile the fact of surface aeration with the existence of an initial temperature overshoot, it is necessary to assume that the temperature drift is due primarily to the removal of sorbed air, resulting in decrease in contact angle, corresponding to improved wetting of the surface. These experiments also indicate that the bulk of the active nuclei are on the heating surface, rather than on dust particles in the liquid.
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