bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Electric Field on the Growth of Thin Metal Films
Authors: Chopra K. L. 
Published: April 2005

It has been found that an electric field applied in the plane of a metal film during deposition induces coalescence of the three-dimensional island-like structure at an earlier stage of the film growth than is obtained without the field. The surface area of the three dimensional islands is increased under applied electric field. The critical thickness, at which the electrically continuous film is obtained, decreases with the increase of electric field. The decrease is more rapid at higher substrate temperatures. Enhanced orientation effects and fewer structural defects have been observed in films deposited under applied field and are attributed to the recrystallization during induced coalescence.
The observed short range order in the coalescence pattern indicates that the applied field transfers and redistributes the electrostatic charges on the islands. It is shown that the presence of a small number of electrostatic charges increases the surface energy and thus the surface area considerably. The electrostatic forces between two islands which either come very close to each other or carry significantly different charges of either polarity are predominantly attractive and are of sufficient magnitude to account for the physical merger. Coalescence as well as breakup of metal islands due to the presence of electrostatic charges on them have been observed on suitably prepared single-crystal lead films irradiated with the imaging electron beam inside an electron microscope.
Pure Space-Charge-Limited Electron Current in Silicon
Authors: Denda S. , Nicolet M-A. 
Published: April 2005

Phosphorus diffusion on π-type silicon is used to fabricate n+πn+ structures of base widths between 3 μ and 60 μ with π-type resistivities of 300 Ω·cm and 8 kΩ·cm. The V-I characteristics of the structures are measured at room temperature and at liquid-nitrogen temperature. The change in current for constant applied voltage is also observed in that temperature range.
The results are interpreted in terms of simple models based on the assumption that pure space-charge-limited current of electrons is present. The models describe well the characteristics measured on 300-Ω·cm samples, except for the range of small biases on the thinnest samples. It is concluded that the drift velocity of electrons at 78°K tends towards saturation at 1.0×107 cm/sec ± 10%. The current observed at this temperature actually reaches this value. The critical electric field at 78°K is 103 V/cm±30% but the meaning of this concept for electrons in silicon is vague. The temperature dependence of the current at fixed bias voltages is in general agreement with the variation of the low field mobility. Results obtained on 8-kΩ·cm samples need clarification. Effects of breakdown and trapping are not observed.
Measurement of Strains at Si-SiO2 Interface
Authors: Jaccodine R. J. , Schlegel W. A. 
Published: April 2005

When Si is thermally oxidized, the SiO2 resulting is in a state of compression on the surface. This paper reports an experimental determination of the magnitude of this stress and its dependence on the temperature of oxidation.
Samples of (111)- and (100)-oriented Si were oxidized at several temperatures between 875°–1200°C to thicknesses of 2000 Å-20 000 Å. Stress determination was made by two techniques: (a) the thin Si sample was used as a beam, and the amount of bowing under the strain exerted by oxide left on one surface was measured; (b) the unsupported SiO2 window was used as a balloon, and strain was measured as a function of air pressure inflating the balloon. Results of these measurements are in agreement with the stress expected from thermal mismatch of Si and SiO2. For an oxidation carried out at 1200°C the measured stress is 3.1×109 dyn/cm2. The data from the SiO2 balloons showed that the strain grown in the oxide was greater than 10−3. In addition, determination was made of Young's modulus from the stress-strain curves of the unsupported films. The value of 6.6×1011 dyn/cm2 obtained compares favorably with the value 7±1.5 1011 dyn/cm2 found for silicate glasses.
Some implications of this stress are briefly discussed. Dislocation generation at borders of holes cut into oxide, bowing and slip processes of slices, impurity segregation, and precipitation are all possible results of this mismatch between the two materials.
Flow and Self-Diffusion of Gases in Capillaries. Part II
Authors: Lund L. M. , Berman A. S. 
Published: April 2005

A variety of experimental data on the pressure dependence of the flow of gases through capillaries are examined using the model presented in Part I. The model is found to provide a good description of flow and self-diffusion in capillaries of arbitrary length-to-radius ratio at pressures ranging from the near free molecule to the continuum regimes.
Experimental free-molecule flows are found to differ from those predicted from existing theories based on the diffuse scattering of gas molecules by the capillary wall. The differences, which in general cannot be explained by specular reflection, are found to depend on the geometrical structure of the surface, the length-to-radius ratio of the capillary, and on the gas being transported.
For a given gas flowing through a capillary of given length-to-radius ratio, the slip contribution to the transport is found to be a monotonically increasing function of the ratio of observed-to-theoretical free-molecule transports.
Atom Ejection Studies for Sputtering of Semiconductors
Authors: Anderson G. S. 
Published: April 2005

Atom-ejection patterns resulting from the sputtering of semiconductor single crystals have been examined. The annealing temperature Ta (here defined as the minimum target temperature for which single-crystal spot patterns are observed) previously reported for Ge, Si, InSb, and InAs, has now been determined for GaAs and CdTe. For target temperatures below Ta damage remains frozen in and the deposit indicates an amorphous or polycrystalline surface. For GaAs one finds Ta∼130°C for Ar+ and Ne+ ion bombardment; for CdTe no spot patterns are observed up to 510°C where the target begins to evaporate. No clear correlation of Ta with other physical properties is noticeable.
We had previously reported that spot patterns persist even for T&lt;Ta if the bombarding-ion energy is less than some critical energy. We have now demonstrated that no such critical energy exists.
The 〈111〉 and 〈1̄1̄1̄〉 deposits resulting from sputtering of InAs and GaAs (110) surfaces were studied. The 〈1̄1̄1̄〉 spot [the normal to the (1̄1̄1̄) face, which terminates with a triply bonded In or Ga atom] is generally slightly thicker (by∼10%) than the 〈111〉 spot. For GaAs the 〈1̄1̄1̄〉 spot is slightly richer in Ga and the 〈111〉 spot is slightly richer in As. No compositional differences were noted for the deposits from InAs.
Measurement of the Very-High-Pressure Properties of Materials using a Light-Gas Gun
Authors: Jones A. H. , Isbell W. M. , Maiden C. J. 
Published: April 2005

Equation-of-state data at extremely high pressure is required for the analysis of many problems pertaining to physics, geophysics, astrophysics, etc. The conventional method used to obtain such data is to impact one flat plate of material against another flat plate at a very high velocity. A shock wave is thus produced in the target plate and the pressure can be deduced by measuring the impact velocity and the shock velocity. American, Russian, and British researchers have used explosive to propel the driver plate to velocities of about 5 km/sec; however, the Russians do not indicate how they accelerate their driver plates for their highest velocities (14–15 km/sec).
The present paper describes an experimental technique in which a 20-mm light-gas gun has been used to accelerate a driver plate against a target at velocities up to 8 km/sec. Tests have been conducted using Fansteel 77 drivers, and Hugoniot data have been obtained for Fansteel 77, tungsten, and gold to about 6-Mbar pressure. The technique is very attractive in that x-ray photographs show that the driver plate is not deformed just prior to impact and has an angle of attack less than 0.5 deg. Also, an analysis of all possible errors in measurement of impact velocity, shock velocity, etc. shows that, with the present technique, Hugoniot data can be obtained to an accuracy of about 1%.
Stress—Strain Curves of Rubbers in Simple Shear
Authors: Mooney M. 
Published: April 2005

It has been stated in a brief report that a gum rubber Hevea stock exhibited a linear stress—strain relationship in two-dimensional shear up to 300% shear. The experimental procedures and results are reported here in detail. Detailed results are reported also of a series of dynamic stress—strain measurements with the St. Joe Flexometer, briefly referred to in 1940. These dynamic shear—shear stress curves are linear within a given stress range. Whenever the greatest previous stress is exceeded, a new linear curve is obtained, of lower modulus.
Nonreversible crystallinity has been generally neglected in theories of rubber hysteresis and in experimental efforts to obtain truly reversible stress—strain curves.
Theory and Measurements of the Glass-Transformation Interval of Polystyrene
Authors: Wunderlich Bernhard , Bodily David M. , Kaplan Mark H. 
Published: April 2005

Equations for the apparent heat capacity in the glass-transition interval as functions of temperature, heating rate, and thermal history have been developed and programmed for computation. The hole theory of liquids was used as basis for the analysis of the glass transition. Experimental information was derived from dynamic differential thermal analysis, DDTA, on polystyrene.
The maximum of the apparent heat capacities found experimentally agrees with the theory. The peak temperatures Tm can be expressed over four decades of heating rates by logq = A′ − B/Tm, where q is the heating rate, A′ is an approximate constant, and B is the activation energy for hole formation. Higher cooling rates lead to higher activation energies on subsequent heating, indicating the need to recognize a hole size distribution.
The minimum in the heat capacity that precedes the maximum on heating through the glass-transition interval could be detected on quenched samples. Mathematical expressions for the minimum temperature and magnitude were developed.
The temperature of ``half-freezing'' on cooling, equivalent to Tool's ``fictive temperature,'' was found experimentally to occur at constant q·τ, where τ is the relaxation time (q·τ = 6.6° for polystyrene). From the ``half-freezing'' temperatures as a function of cooling rate one can determine the properties of a ``mean hole.'' For polystyrene the activation energy of the mean hole is 157 600 cal/mole of holes.
Reduction of Dielectric Loss in Polyethylene
Authors: Conklin Glenn E. 
Published: April 2005

A mechanism contributing to the dielectric loss at 55.2 Gc/sec in highly crystalline polyethylene has been identified. The manufacturing process introduces imperfections in the form of vinyl unsaturation which can orient in the presence of a microwave field. Hinderance to orientation, in similar cases, by neighboring atoms is known to produce losses. The dielectric loss tangent of the polyethylene was found to decrease by a factor of 1.5 from 4.5×10−5 when the vinyl groups were destroyed with a small amount of gamma irradiation. Furthermore, the dielectric loss attributable to the vinyl unsaturation was found to vary linearly with the vinyl concentration as indicated by the associated infrared absorption coefficient of the 11.0-μ vinyl line, and to be consistent with the view that the unsaturation is homogeneously distributed in the polyethylene.
A technique for the measurement of the complex dielectric constant of isotropic solids at millimeter wave frequencies is described which utilizes a unique property of the TEono modes in circular waveguide. For these modes the tangential electric field vanishes at all points on the waveguide wall. This gives rise to the important results that wall loss corrections to the complex dielectric constant are relatively minor and that the effects of the air space at the junction between sections of waveguide are also minor provided the length of the space is less than about λ/6.
Dislocations in Polyethylene Single Crystals
Authors: Holland V. F. 
Published: April 2005

Dislocations have been observed and characterized in polyethylene single crystals by means of moiré patterns produced by superimposed lamellas. Analysis of the dislocations by dark and bright field electron microscopy has revealed that they are partial (imperfect) dislocations. The partials were shown to involve terminating {110} planes and to have Burgers vectors of 〈½a, ½b, γc〉. Most of the dislocations involved {110} planes containing chain folds. The occurrence of the dislocations as isolated partials rather than paired ones implies a low stacking fault energy for the polyethylene lattice. This conclusion is not surprising when one considers that the ``faults'' consist mostly of chains which simply have been rotated from their normal positions.
Annealing of single crystals increased approximately one-thousand fold the dislocation density, and in addition produced, in dark field, bands parallel to the long diagonals of the crystals. These bands were found predominantly at the crystal edges. Selected area electron diffraction of the annealed crystals revealed that a monoclinic crystal phase, previously observed in stressed polyethylene, was concentrated near the crystal edges. The fact that the reported chain packing in the monoclinic phase is similar to that of a possible stacking fault in the orthorhombic lattice implies a definite relationship between the formation of partial dislocations and the occurrence of the monoclinic phase. These results suggest that dislocations play an important part in the annealing of polyethylene single crystals and perhaps of other polymers as well.
Nature of Spontaneous Oscillations in a Cesium Diode Energy Converter
Authors: Norris W. T. 
Published: April 2005

In an attempt to understand the nature of the oscillations that are observed in plasma diodes the usual collision-free model is examined. The equations describing the model are simplified by neglecting the time-dependent term in the Boltzmann equation for the electrons. Even this simplification does not readily yield quantitative predictions about the frequency or form of the oscillations, or even about the conditions under which they are likely to occur.
However we introduce a criterion of stability which allows us to predict a possible instability in the steady-state condition which arises because the electrons can redistribute their charge more rapidly than the ions. The simplified equations and the criterion together lead to a good qualitative and a partial quantitative understanding of a particular case. The particular case can be regarded as the epitome of the general case, and the arguments used in it seem capable of the necessary extension to cover all instances of this sort of spontaneous oscillation.
Strain and Precision Lattice Parameter Measurements by the X-Ray Divergent Beam Method. I
Authors: Ellis T. , Nanni L. F. , Shrier A. , Weissmann S. , Padawer G. E. , Hosokawa N. 
Published: April 2005

An X-ray method is described which permits a precise determination of the interplanar spacings in a crystal. The method is capable of disclosing small differences in interplanar spacings even between various sets of (hkl) planes of the same form and, therefore, serves as a basis for a stress-strain analysis. An error analysis of this method shows that the minimum measurable strains in the lattice, expressed as Δd/d, are a function of the diffraction angle θ. For θ varying from 35° to 65°, the minimum measurable strains vary from 0.03% to 0.009%.
A precision determination of the lattice parameter of a zone-refined tungsten crystal yielded a0=3.16566±0.00002 Å. Limitations and possible applications of the method to problems in physical metallurgy and solid state physics are presented.
Stress-Strain Analysis of Single Cubic Crystals and Its Application to the Ordering of CuAu I. Paper II
Authors: Slade J. J. , Weissmann S. , Nakajima K. , Hirabayashi M. 
Published: April 2005

A stress-strain analysis of single cubic crystals is developed which utilizes the strain data supplied by the x-ray back-reflection divergent beam method. The principal strains and their directions are determined and from the principal strains and the known elastic constants the complete stress-strain configuration is obtained. Thus the maximum magnitude and the direction of the shearing strain on a given set of crystallographic planes are obtained and the set of planes on which the maximum value of the shearing maxima occurs is also determined. From a knowledge of the stress-strain configuration, the stored elastic energy of the crystal is deduced; it can be partitioned into two components, that due to shearing strains and that due to a mixture of normal and shearing strains.
The conditions under which the principal stress system coincides with the principal strain system are also investigated. Furthermore, a number is constructed that measures the distortion of the crystal in terms of the energy increments associated with the elastic constants.
The stress-strain analysis applied to the ordering of a CuAu crystal at 125°C corroborates quantitatively the qualitative results previously obtained by transmission electron microscopy. The dependence of stored elastic energy on annealing time is determined and it is shown that the first maximum and decline are associated with the maximum and decline of coherency strains set up between the ordered CuAu I nuclei and the disordered matrix. Upon increasing the annealing time, twinning occurs to relieve the tetragonality strains introduced by the ordered CuAu I domains. The second maximum is compounded by twinning on certain (110) planes and delayed ordering on other (110) planes of the matrix. The subsequent decline of the stored elastic energy is associated with twinning on all (110) planes. The shearing stress necessary to initiate microtwinning does not exceed 7×108 dyn/cm2.
Thermal Conductivity of Pure and Impure Silicon, Silicon Carbide, and Diamond
Authors: Slack Glen A. 
Published: April 2005

Thermal conductivity measurements on high-purity SiC and impure Si and SiC have been made over the temperature range from 3° to 300°K. These results show that the thermal conductivity K, of the highest purity SiC is intermediate between those of pure Si and pure diamond, and at 300°K is greater than that of copper. The heat transport in SiC is produced by phonons and these are scattered by other phonons, isotopes, and the crystal boundaries in the pure material.
In impure SiC the phonons are also scattered by the electrically active impurities Al and N. These impurities reduce the K of SiC in much the same way that B and P impurities do in Si. The N impurities in natural diamonds also reduce their K below that of ideally pure diamond, but the effect is rather different since N is not electrically active.
Low-Energy Electron Diffraction Study of Graphite
Authors: Lander J. J. , Morrison J. 
Published: April 2005

A low-energy electron diffraction study of surface properties of single-crystal graphite revealed that unlike silicon, germanium, or diamond, the basal plane at the surface was not reconstructed nor did it chemisorb H2O, O2, CO, Br2, or I2 in monolayer quantities at low pressures and moderate or high temperatures.
Elastic and inelastic electron scattering factors for graphite and their contributions to diffraction effects have also been evaluated. The layered structure serves to simplify certain analytical problems and, in particular, results in an energy region from about 10 to 70 V where one-dimensional analysis provides first-order estimates of these scattering factors. But it is also seen that from the point of view of complete and precise quantitative analysis, the elastic and inelastic scattering amplitudes, phase effects, three-dimensional effects, and dynamic factors are almost inextricably entangled in the energy region below about 70 V. Above this region the diffraction effects are largely kinematic and analysis is much simpler.
Diffusion and Solubility of Copper in Extrinsic and Intrinsic Germanium, Silicon, and Gallium Arsenide
Authors: Hall R. N. , Racette J. H. 
Published: April 2005

The solubilities of substitutional and interstitial copper (Cus and Cui) have been measured in intrinsic and extrinsic n- and p-type Ge, Si, and GaAs, using Cu64. These measurements show that Cus is a triple acceptor in both Ge and Si, and that Cui is a single donor in all three semiconductors. Charge compensation experiments show that Cus is a double acceptor in GaAs. In intrinsic semiconductor near 700°C the ratios of substitutional to interstitial solubilities are 6, ∼10−4, and 30, respectively. Electrically active donors due to Cui have been observed in Si by Hall-effect measurements. Pairing between Cus and donors is pronounced in n-type Ge but relatively unimportant above 600°C in Si. There is no evidence for pairing between Cui and acceptors in any of these semiconductors.
The interstitial diffusion coefficient Di is independent of doping in extrinsic p-type material. At 500°C, Di=2.8, 0.76, and 1.0×10−5 cm2/sec with activation energies of 0.33, 0.43, and 0.53 (±10% in each case) eV, respectively. Di and the single positive charge of Cui in p-type GaAs have been confirmed by drift experiments.
The decrease in energy gap with acceptor doping is 0.28 eV in Ge and 0.14 eV in Si at 4×1020 cm−3 acceptors, as deduced from Cui solubility data.
KCN solutions remove Cu effectively from surfaces and from liquid Ga. Ga is much more effective than molten KCN in extracting Cu from the interior of semiconductors. KCN contains Cu and may actually introduce Cu instead of removing it.
Preparation of Peritectic-Type Intermetallic Compounds by a Modified Čzochralski Method
Authors: Barber D. J. 
Published: April 2005

The growth of single crystals of peritectic-type intermetallic compounds has been investigated for binary aluminium-rich systems. Single crystals of MnAl6 and NiAl3 have been grown in this way.
In principle, the method is suitable for the extraction of high-temperature phases which transform peritectically at lower temperatures and thus cannot easily be obtained in bulk form (e.g., MnAl4, which can transform into MnAl6). In practice, preliminary work indicates that the experimental requirements are difficult to realize.