bluuebunny/crossref_metadata_2025_split huggingface dataset:
GaAsGaP Heterojunctions
Authors: Davis M. E. , Zeidenbergs G. , Anderson R. L. 
Published: July 2007

AbstractGaAsGaP n–n, n–p, and p–n heterojunctions were fabricated by growing GaAs onto GaP substrates using HCl as the transport agent in an open‐tube system. It is found that the conduction band is continuous at the interface. This is in contrast to reported discontinuities of 0.65 and 0.22 eV. A high concentration of interface states is present in such junctions as evidenced by the frequency dependence of capacitance, and the I–U characteristics. Photocurrent response is as expected in n(GaAs)–p(GaP) heterojunctions, but a modulation effect was observed in p(GaAs)–n(GaP) junctions. This effect is not well understood.
The kohler rule of magnetoresistance in neutron‐irradiated aluminium at 4.6°K
Authors: Böning K. , Fenzl H. J. , Olympios E. , Welter J. M. , Wenzl H. 
Published: July 2007

AbstractAn investigation is made of the range of validity of the Kohler rule for the transverse magnetoresistance of aluminium at 4.6°K by introducing structural defects with different concentration and configuration by low temperature reactor irradiation and subsequent annealing. – During irradiation the Kohler rule is extremely well satisfied, because in this case only the concentration of identical defects is enlarged. After step‐annealing, however, there are large deviations, because the structural defects not only recombine but also rearrange to other configurations, which corresponds to a change in the mean scattering anisotropy. The influence of small angle scattering is to be seen well in the measurement curves.
The Investigation of Electroconductivity and Viscosity of the Melt CdGeP2
Authors: Serednii A. P. , Goryunova N. A. , Tychina I. I. , Nikolskaya G. F. , Evfimovskii I. V. , Novikova A. N. , Kovaleva I. S. 
Published: July 2007

AbstractAn investigation of the conductivity and viscosity of semiconducting compound CdGeP2 in the liquid state has been made. It has been found that the transition of this compound from the solid to the liquid state coincides with the pattern “semiconductor → semiconductor”. The value for the activation energy of the conductivity of the melt completely coincides with the energy gap of vitreous CdGeP2. It might be explained with the similar structure of the short‐range order.
Creep Kinematics of Cross‐tie Domain Walls
Authors: Telesnin R. V. , Ilyicheva E. N. , Kanavina N. G. , Osukhovskii V. E. , Shishkov A. G. 
Published: July 2007

AbstractDomain‐wall creep was studied by the powder pattern method. To increase the resolution of the boundary pictures, microphotometry of the photographs was made. The centre of the boundary on the film was determined to an accuracy of ± 0.05 μm. The direct observation of elementary acts of creep enables to substantiate and refine the kinematic creep model – the model of varying boundary curvature. The curvature variation is due to the variation in the boundary rigidity as a result of the induction of magnetostatic “charges”.
Cation Distribution in Gallium‐Substituted Yttrium Iron Garnets by Mössbauer Effect Spectroscopy
Authors: Czerlinsky E. R. 
Published: July 2007

AbstractRecoil‐free nuclear‐resonance absorption was measured on Y3GatFe5‐tO12 powders with 1.75 ≦ t ≦ 4.0. A constant acceleration spectrometer was used, and the investigations were performed at room temperature, that is, above the Curie temperature of these compounds. For each material, we observed three resonant absorption maxima with different heights. The position of the maxima on the velocity scale is independent of composition. For each spectrum, two doublets which arise from the quadrupole splitting of the 57Fe nuclei are assigned; one doublet arises from the 57Fe nuclei in the tetrahedral(d) sites, whereas the other arises from the 57Fe nuclei in the octahedral (a). From the relative values for the intensities D and A for the d‐and a‐sites together with the known amount of t, the fraction x/t of the Ga3+ ions in the d‐sites was determined for each compound. The results were compared with work on cation distribution in substituted garnets obtained from 1. magnetization measurements, 2. X‐ray and neutron diffraction, and 3. thermodynamics of solid solutions. At Ga concentrations t ⪆ 2.0, our results deviate from the ones obtained from magnetization data. The distribution function proposed under 3. from the equilibrium conditions for ions in multisublattice structures is consistent with the experimental data presented in this paper.
Effect of Doping on the Shift of the Optical Absorption Edge for Circularly Polarized Waves in a Magnetic Field and on the Interband Faraday Rotation in n‐Type GaAs
Authors: Theilemann W. 
Published: July 2007

AbstractThe difference of the shift of the optical absorption edge for σ‐ and σ+ polarized waves in a magnetic field is measured on a series of n‐type GaAs samples with various doping levels. The measurements are performed at 77 and 300°K. Following the theory of Luttinger and Kohn[1] the shift of the absorption edge was calculated under the assumption of a broadening of the Landau levels in such a manner as to yield exponential tails with decreasing energy. The assumption of such a broadening is justified since it is known that there are state density tails which extend exponentially decreasing into the gap [2,3]. The effect of doping is considered by applying the Fermi distribution function to the electrons in the Landau levels of the conduction band. The position of the Fermi level and the shape of the absorption edge are determined by absorption measurements. The calculation is in good agreement with the experiment and permits also the explanation of the effect of doping on the interband Faraday rotation near the absorption edge.
Mößbaueruntersuchungen an Sn119‐dotiertem AgCl
Authors: Meisel W. , Schnorr H. , Hennig K. 
Published: July 2007

AbstractEs wurden die Mößbauerspektren des Sn119 in AgCl‐Polykristallen, die mit 0,05 mol% Sn119 dotiert waren, gemessen. Die Spektren zeigen jeweils eine einzelne Linie mit einer sehr geringen Temperaturabhängigkeit ihrer Intensität. Aus der Isomerieverschiebung folgt, daß das Zinn als Sn4+ vorliegt. Als mikroskopisches Modell wird der Einbau von Sn119 auf Zwischengitterplatz, umgeben von vier Kationenlücken, erörtert.
Internal Friction due to Long‐Range Diffusion of Hydrogen in Niobium (Gorsky Effect)
Authors: Cantelli R. , Mazzolai F. M. , Nuovo M. 
Published: July 2007

AbstractThe Gorsky effect is investigated by internal friction measurements in the niobium‐hydrogen system at a vibration frequency of 16 Hz. The diffusion coefficient D of hydrogen in niobium is measured as a function of temperature. It is found that D, in the temperature range from ≈︁ 235 to ≈︁ 830 °K, obeys the Arrhenius relation D = D0 exp [– W/kT] with D0 = 5.4 × 10−4 cm2/s and W = (0.109 ± 0.005) eV. A deviation from the exponential law is observed at lower temperatures.
Study of Symmetrical Walls in Permalloy and Lorentz Microscopy
Authors: Vigier P. , Haymann P. 
Published: July 2007

AbstractIt is shown that the deformations in thin ferromagnetic films submitted at a magnetic perpendicular field involve the existence of “symmetrical walls”, energies which widths are calculated. The experimental study is achieved by the Lorentz microscopy where a peculiar contrast is associated with those walls.
Scattering of Carries by Charge Centres Under Conditions of Quantum Size Effect
Authors: Shik A. Ya. 
Published: July 2007

AbstractThe relaxation time of electrons in very thin films is calculated assuming the electrons are scattered by a screened Coulomb potential. The specific peculiarities of the screening in thin films is taken into account. It is shown that the conductivity may decrease with the film thickness. Comparison with experimental results is made.
Paramagnetic Relaxation in Dysprosium and Terbium Ethyl Sulfate with Regard to Various He Baths
Authors: Kump U. 
Published: July 2007

AbstractThe relaxation behaviour of dysprosium and terbium ethyl sulfate immersed in liquid 3He and 4He was studied. In the case of dysprosium ethyl sulfate measured in the temperature range 0.8 ⪅ T ⪅ 1.4 °K there was found a direct process for an external magnetic field parallel to the crystallographic symmetry axis of the crystal. The contribution of heat conduction in the 3He and normal fluid 4He to the measured relaxation times has been estimated from the results on terbium ethyl sulfate.
Linear Stark and Pseudo‐stark Effect of the F Centre in LiF and NaF
Authors: Johannson G. , Von Der Osten W. , Piehl R. , Waidelich W. 
Published: July 2007

AbstractA linear Stark and pseudo‐Stark effect is observed at the zero‐phonon absorption lines 5456 Å in NaF and 4874 Å in LiF at 4.2 °K. From the combination of uniaxial stress and electric field results the corresponding colour centre is found to belong to the C3v point symmetry group. In accordance with the model for the ionized R centre (F centre) the lines are due to transitions between a single ground state and a degenerate excited state. For the analysis of the experimental results the method of moments is used and a comparison with the Stark and pseudo‐Stark effect of the R centre is presented.
The Conduction Mechanism of Self‐Compensated Highly Disordered Semiconductors (A Possible Model for Semiconducting Glasses)
Authors: Böer K. W. 
Published: July 2007

AbstractAmbipolar conduction in a self‐compensated highly disordered semiconductor with the Fermi‐level pinned close to the middle of the band gap is discussed and it is shown that predominant p‐type conduction occurs because of a higher effective level density in the narrower valence band, which usually is not compensated by a lower hole mobility due to a higher effective mass of holes. Because of a non‐negligible contribution of minority carriers, the Hall‐mobility is considerably lower than the actual carrier mobilities and can vanish and even invert its sign, if the major carrier transport takes place higher inside the bands where the effective masses increase markedly and/or if the Fermi‐level lies slightly above the middle of the band gap. The shift of the carrier transport into the bands is assumed to be caused by small potential barriers extending from the band edges into the band and being due to a sufficient density of charged centers. The results of this model are compared with experimental findings on a chalcogenide Ge0.33As0.2Te0.2S0.27‐glass yielding mn = 0.2 m0, mp = 1.6 m0, μn = 210 cm2/Vs, μp = 75 cm2/Vs, n = 5 × 107 cm−3, and p = 4 × 108 cm−3 for an observed semiconductivity of 5 × 10−9 Ω−1 cm−1 and Hall‐mobility of −0.5 cm2/Vs at room temperature. The activation energy for semiconductivity is 0.72 eV, the optical band gap ≈︁ 0.9 eV, yielding a barrier height within the bands of ≈︁ 0.25 eV.
The Conduction Mechanism of Highly Disordered Semiconductors (A Possible Model for Semiconducting Glasses) II. Influence of Charged Defects
Authors: Böer K. W. 
Published: July 2007

AbstractThe band perturbation due to a high density of charged defects is discussed, and it is shown that the saddle point between Coulomb‐repulsive centers can act as a potential barrier, above which conductivity takes place, if the average distance between these saddle points is small compared to the mean free path of the carriers. For a defect density of 1020 cm−3 the saddle points lie ≈︁ 0.25 eV from the respective band edges and are an average of 20 Å apart from each other, while the mean free path, as calculated from ion‐scattering for carriers of an energy 1 kT above these saddle points is about three times as large. These potential barriers are suggested to be responsible for the fact, that for glasses the thermal activation energy for semiconductivity is usually 0.1 to 0.3 eV larger than half the optical band gap.
Superlinear Photoconductivity
Authors: Stöckmann F. 
Published: July 2007

AbstractUsing the method described in the preceding paper [1] general conditions are derived for the case that a photocurrent increases stronger than linear with the excitation strength G. If this so‐called superlinear photoconductivity is caused by a superlinear dependence of the majority carrier concentration on G, the necessary and sufficient conditions for an n‐type conductor are as follows: 1. With increasing G a group of imperfections whose concentration is sufficiently large and which were essentially unoccupied before, has to be fully occupied by electrons. 2. There must not simultaneously be a group of hole traps fully occupied by holes. 3. The rate determining slowest process in the recombination mechanism must be the capture of holes by the recombination centres.
Experimental Study of the Conduction Band of GaSb
Authors: Bordure G. , Guastavino F. , Llinares C. 
Published: July 2007

AbstractSimultaneous Faraday rotation, reflectivity, and Hall effect measurements made on two Te doped, n‐type GaSb single crystals of various doping, have been used to determine the characteristics of the L1 conduction band minimum as a function of the ratio K = m1*(L1)/mt*(L1).Using the theoretical value K = 13, we have obtained for the transverse effective mass of the (111) minimum electrons and for the energy separation of the L1 and Γ1 minima: mt*(L1) = 0.12 me and ΔE = 83 meV at 300°K with d(ΔE)/dt = 5.5 × 10−5eV/°K. Complementary conductivity measurements were made to obtain the mobilities of the two conduction band carriers.
F Band Absorption in Alkali Halides as a Function of Temperature
Authors: Dawson R. K. , Pooley D. 
Published: July 2007

AbstractMeasurements have been made of the F centre optical absorption function for all twenty alkali halides at seven temperatures between ≈ 5 and 300 °K. The measurements have been fitted with a shape function consisting either of an unsymmetrical Gaussian band or, for the halides of cesium, of three symmetrical Gaussian bands of equal intensity, and the appropriate band parameters derived. The results are given of fitting the temperature variations of these parameters with the predictions of theory using one and two interacting vibrational modes. The variation of basic parameters from halide to halide is discussed.
The Influence of Hindered Rotation of Molecules in Molecular Crystals on the Spectral Parameters of Nuclear Quadrupole Resonance
Authors: Lotfullin R. Sh. , Semin O. K. 
Published: July 2007

AbstractThe influence of anisotropic reorientation movements of molecules in molecular crystals on NQR spectral parameters (frequency v; quadrupole coupling constant e2qQ, asymmetry parameter of the electric field gradient η, spin–lattice (T1) and spin‐spin (T2) relaxation times) has been considered theoretically by the spectral density method. The calculations were performed considering the different nuclear spins. It is necessary to differentiate between models with “rapid” and “slow” (compared to the experimental frequency) reorientations.
Reactions between Perfect Dislocations in Semiconductor Devices
Authors: Sauvage M. , Simon D. 
Published: July 2007

AbstractSemiconductor devices of “thyristor structure” are studied by the X‐ray topographic method. Typical perfect dislocations are generated in n‐p junction and glide in neighbouring {111} slip planes close to the crystal surface, thus contributing to the relaxation of stresses located at the boundary between the two regions of different lattice parameters. — Dislocation reactions are observed and interpreted on the basis of a cross‐slip mechanism. The reaction product is an edge segment of sessile type increasing the brittleness of the silicon sample.
Preparation and Some Physical Properties of ZnGeP2
Authors: Ray B. , Payne A. J. , Burrell G. J. 
Published: July 2007

AbstractSingle crystal ZnGeP2 has been prepared by slow cooling from the melt and by vapour transport of the constituent elements in a phosphorus atmosphere. X‐ray powder studies lead to a c/a ratio for the chalcopyrite‐structured ZnGeP2 of 1.961. Thermal analysis measurements give a phase change at (952 ± 2) °C, probably disordering of chalcopyrite to zinc blende, and congruent melting at 1025 °C. Resistance‐temperature investigations suggest that acceptor levels at 0.10 and 0.62 eV control the free carrier concentration above and below room temperature, respectively. Undoped ZnGeP2 is always p‐type. Minority carrier studies point to an electron mobility between 103 and 104 cm2/Vs. Photoconductivity and optical absorption measurements lead to the conclusion that the direct energy gap in ZnGeP2 is 2.25 eV.
Conducting and Insulating Incorporation of Antimony into the BaTiO3 Lattice
Authors: Schmelz H. 
Published: July 2007

AbstractSb‐doped BaTiO3 is semiconducting only within a relative narrow concentration range. An explanation of this fact requires the knowledge of the lattice site occupied by the Sb. By means of X‐ray diffraction, neutron diffraction, and microprobe analysis it could be shown that Sb concentrations up to 10 at% are completely incorporated on Ti sites if an equivalent amount of Ti vacancies is offered, whereas the Sb substitutes Ba sites only partly even in the presence of an excess of TiO2. The Sb can cause conductivity in BaTiO3 only if it is incorporated on Ba sites. For this purpose a high excess of TiO2 is required. The transition from conducting to insulating incorporation is explained by a trapping mechanism caused by coupling of Sb with Ba vacancies taking into account the influence of the barrier layers.
Cyclotron Resonance in Tellurium
Authors: Radoff P. L. , Dexter R. N. 
Published: July 2007

AbstractCyclotron resonance of electrons and holes has been observed in tellurium single crystals at 24 and 70 GHz and at liquid helium temperatures. In pure specimens and at low temperatures the surfaces of constant energy for the holes are well described by 4 prolate ellipsoids of revolution about the c‐axis located near the Brillouin Zone corners. At higher hole energies produced by thermal or optical excitation or by heavily doping the crystals, pairs of these ellipsoidal surfaces degenerate into dumbbell‐shaped surfaces of revolution. The observed isotropic resonance of high mass electrons (m* = 0.75 m0) suggests an indirect gap at low temperatures.
Epitaktisches Wachstum von Oxiden auf Eisen im Hochtemperatur‐Elektronenmikroskop
Authors: Golob P. , Horn H. , Warbichler P. 
Published: July 2007

AbstractEs wird die Erscheinung der Epitaxie von Eisenoxiden auf Eisen untersucht, wobei zwei Oxidmodifikationen beobachtet wurden. Während die hexagonalen plättchenförmigen Kristalle zwanglos dem α‐Fe2O3zugeordnet werden können, gelingt eine Identifizierung nur auf Grund ihrer Erscheinungsform bei den würfelförmigen Kristallen nicht. Es wurde deshalb dieses Oxid mittels streifender Elektronenbeugung untersucht und als γ‐Fe2O3identifiziert. Die Epitaxie beider Modifikationen konnte gittergeometrisch erklärt werden.
Stopping Cross Sections of Li+ Ions with Energies from 30 to 100 keV in Various Target Materials
Authors: Bernhard F. , Müller‐Jahreis U. , Rockstroh G. , Schwabe S. 
Published: July 2007

AbstractThe electronic stopping cross sections for lithium ions in carbon, aluminium, titan, nickel, and copper are reported. The dependence on energy in the interval from 30 to 100 keV and on the atomic number of the target atoms are investigated. By using some data from other authors a characteristic dependence of the electronic stopping cross section on the atomic number of the target atoms is found.
Phonon Widths in Nacl, KCl, and RbCl from Neutron Measurements
Authors: Raunio G. 
Published: July 2007

AbstractIn a systematic study of phonon dispersion relations in NaCl, KCl, and RbCl results were also obtained on phonon widths in some branches, primarily at 80 °K, but to some extent also at 300 °K. The widths for all three chlorides are found to be mostly between 0.04 and 0.10 (in units of 1013 rad s−1). In all cases the increase of the width between 80 and 300 °K is less than the estimated error of the width at 80 °K. The results are discussed and some of the difficulties of such measurements are pointed out.
Interpretation of Self‐Diffusion and Vacancy Properties in Copper
Authors: Mehrer H. , Seeger A. 
Published: July 2007

AbstractRecent tracer measurements of the self‐diffusion coefficient by Rothman and Peterson are analysed in conjunction with the determination of equilibrium concentrations of vacant lattice sites by Simmons and Balluffi and the isotope effect on self‐diffusion. The following values for monovacancy and divacancy properties are obtained (in the usual notation): E = 1.03 eV, E = 1.06 eV, S ≈ 0.3 k, E − E 0.54 eV, divacancy association entropy ΔS2 V ≈ 2 k, temperature coefficient of monovacancy self‐diffusion energy 2 α = d (E + E)/d(kT) ≈ 0.5, frequency factors for mono‐ and divacancy migration v exp (S) = 1.4 × 1014 s−1, v exp (S/k) = 1.6 × 1014s−1. The monovacancy jump frequencies near room temperature are in excellent agreement with the values obtained from dislocation pinning experiments of Thompson and Paré.
Intrinsic Stacking Faults on {112} Planes in the B.C.C. Lattice
Authors: Eichler H. , Pegel B. 
Published: July 2007

AbstractThe possibility of intrinsic stacking faults in the b.c.c. lattice is discussed for a central force model. The existence of stable stacking faults depends on the cut‐off radius of the interatomic potential. For rather small cut‐off radii the model predicts stacking faults. However, we obtain stacking fault vectors different from those predicted by the hard‐sphere model. Further, the asymmetry of the stacking fault energy surface with respect to displacements in ± 〈111〉 directions depends on the cut‐off radius.
Diffusion of Zinc in Lithium
Authors: Mundy J. N. , Ott A. , Löwenberg L. , Lodding A. 
Published: July 2007

AbstractExperimental details are given of a thin film sectioning technique for the measurement of tracer diffusion in lithium metal. Results are given for 65Zn in Li between 57 and 173 °C. They are expressed by D = D0exp ( − Q/RT), where \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {0.57\begin{array}{*{20}c} { + 0.31} \\ { - 0.20} \\ \end{array}} \right){\rm cm}^{\rm 2} {\rm /s} $\end{document} and Q = = (12.98 ± 0.24)kcal/mol. The activation energy equals, within margins of error, that of self‐diffusion in Li. The agreement between vacancy based theories and the present results appears rather doubtful.
Optical Effects of Free Carriers in Thin α‐Ag2S Films
Authors: Geserich H. P. , Suppanz W. 
Published: July 2007

AbstractThe intrinsic and the free carrier absorption has been investigated in thin α‐Ag2S films as a function of carrier concentration. By producing an excess of silver the electron concentration in α‐Ag2S increases from the intrinsic concentration value ne = np = 1.2 × 1018 cm−3 up to ne = 3.6 × 1019 cm−3 (at 200 °C). Since the silver to sulfur ratio cannot be frozen in, either the chemical potential of silver or that of sulfur must be fixed by external conditions during the measurements. From the spectral dependence of the dielectric constant direct transitions (ΔEdirect = 0.87 eV), the conduction band mass (m*e = 0.24 m0) and the scattering mechanism of the electrons (scattering by charged centres) were determined. It was not possible to deduce the band gap (≈ 0.1 eV from electrical data) from optical measurements.
The Change of Sound Velocity at the Bose‐Einstein Condensation of Excitons in Crystals
Authors: Miglei M. F. , Moskalenko S. A. , Lelyakov A. V. 
Published: July 2007

AbstractBelyaev's equations are generalized for the case of a non‐ideal gas of excitons interacting with the phonons in the crystal at T = 0. In the first approximation of the perturbation theory the energetic spectrum of the elementary excitations is received. The change of sound velocity in some crystals is calculated for different assumptions with reference to the constants of exciton‐exciton and exciton‐phonon interactions.