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Showing papers on "Effective mass (solid-state physics) published in 1974"


Journal ArticleDOI
TL;DR: In this article, the optical plasma resonance absorption of small silver particles embedded in glass has been investigated, and it has been shown that normal metallic properties are present in silver particles which contain more than about 400 atoms.
Abstract: Specimen size dependences of the dielectric constant and of its variations with temperature have been investigated by measuring the optical plasma resonance absorption of small silver particles embedded in glass. The following relations hold at the wavelength 405 nm: epsilon 2 (imaginary part at 300K)=0.23+2.64/R, and epsilon 2(300K)- epsilon 2(1.5K) approximately=0.07-0.08/R where R is the particle radius in nm. Agreement has been found with the free path effect but not with the quantum size effect theories of Kawabata and Kubo (1966) and of Glauberman and Adamyan (1969). The behaviour of the temperature dependence can partly be explained by thermal lattice contraction. The ratio of electron density to the optical effective mass shows no distinct changes as R varies from 10.5 nm to 1.1 nm. It may hence be concluded that normal metallic properties are present in silver particles embedded in glass which contain more than about 400 atoms.

501 citations


Journal ArticleDOI
TL;DR: In this paper, the properties of rare earth compounds with mixed valency have been investigated, including SmB6, SmS, SmSe and SmTe, and it is suggested that the low-pressure form of SmS is an excitonic insulator.
Abstract: This paper reviews the properties of certain rare-earth compounds in which the 4f band has mixed valency, notably SmB6 and the high-pressure forms of SmS, SmSe and SmTe. The metal-insulator transitions of the last three materials under pressure are discussed. It is suggested that the low-pressure form of SmS is an excitonic insulator. In SmB6 and high-pressure SmS a very small gap separates occupied from unoccupied states, this in our view being due to hybridization of 4f and 5d bands. The electrical properties are discussed; if kT is greater than the gap energy, then the gap does not affect the metallic behaviour. Finally metallic compounds such as CeAl3 are described, in which there is no magnetic ordering at low temperatures, and it is suggested that this must always occur if the Kondo temperature is higher than the RKKY interaction. In this case, as in compounds with mixed valency, the Fermi energy will pass through the 4f band, and there is a very large enhancement of the effective mass. The...

175 citations


Journal ArticleDOI
TL;DR: In this paper, two species of surface states are discussed: weakly bound by the image force and an electron bubble held below the interface with an applied field, and a resonance experiment in this geometry determines an effective mass different from the bulk liquid value.
Abstract: Electrons at the surface of liquid $^{4}\mathrm{He}$ are potentially valuable probes of both static and dynamic properties of the interface. Two species of surface state are discussed. One of these is localized just above the interface, weakly bound by the image force. The existence of this state has been confirmed by direct spectroscopic observation. Measurements of parallel field mobility and life-time on the surface are discussed and compared with predictions. The other surface state is an electron bubble held below the interface with an applied field. A resonance experiment in this geometry determines an effective mass different from the bulk liquid value. Studies of field emission from the bubbles lead to an evaluation of other bubble properties.

167 citations


Journal ArticleDOI
TL;DR: In this article, the magneto-stark effect and electronic transport properties on GaSe have been studied and it has been shown that GaSe has nearly isotropic electronic states at the forbidden gap and the valence band anisotropy is anomalous.

112 citations


Book ChapterDOI
TL;DR: In this article, a two-valence band model was proposed for lead-salt ionic semiconductors, based on the properties of PbS, PbSe, and PbTe.
Abstract: Publisher Summary Lead salts are ionic semiconductors with many properties in common. Their IV-VI electron configuration is relatively unusual, and appears to be reflected in the interesting phonon and dielectric properties they share. Among these are low values of the TO phonon frequency at Γ and high static dielectric constants. It is clear that the electronic structures of PbS, PbSe, and PbTe are much the same, with all three lead salts exhibiting a direct minimum energy gap E 0 at the L point. The surfaces of constant energy for both electrons and holes are ellipsoidal near the band edges, but approach a cylinder-like shape farther from the L point. The conduction and valence bands in all the lead salts are definitely nonparabolic, displaying a concomitant dependence of the effective mass on carrier concentration. Based primarily on studies of PbTe, a two-valence band model is well supported by experiment. The order of higher energy bands appears quite well established, and reliable values of the energies of several interband transitions have been obtained.

70 citations


Journal ArticleDOI
TL;DR: In this article, the tunneling characteristics of Cr/SiO2/Si structures in the thickness range 23-34 A were reported and the E −κ dependence in the energy range extending 3.5 eV below the oxide conduction band was determined by the thickness dependence to be approximately of the Franz form with an effective mass ratio of 0.42.
Abstract: The tunneling characteristics of Cr/SiO2/Si structures in the thickness range 23–34 A are reported. The E‐κ dependence in the energy range extending 3.5 eV below the oxide conduction band is determined by the thickness dependence to be approximately of the Franz form with an effective mass ratio of 0.42. Tunneling into the indirect conduction band of silicon is reduced by a thickness‐independent factor which decreases approximately exponentially with the energy below the direct band edge.

68 citations


Journal ArticleDOI
TL;DR: In this paper, the resistivity and Hall coefficient for undoped p-type CuGaS2 were measured at temperatures between 77 and 400°K, where the acceptor ionization energy increased from 0.073 to 0.39 eV with the decrease of acceptor concentration.
Abstract: The resistivity and Hall coefficient for undoped p‐type CuGaS2 were measured at temperatures between 77 and 400°K. The crystals were grown from both the stoichiometric melt and the vapor phase. The crystals were heat treated under an excess sulfur atmosphere in the temperature range 400–660°C. An analysis of the hole concentration data showed that the heat treatment changed the acceptor concentration from 6×1014 to 2×1018 cm−3. The acceptor ionization energy increased from 0.073 to 0.39 eV with the decrease of the acceptor concentration. The effective mass of the hole in CuGaS2 from the Hall analysis was ∼0.69me. The formation energy of the Cu vacancy, which is presumably an intrinsic acceptor, was ∼0.68 eV in CuGaS2. The acceptor energy of the Cu vacancy in the lower concentration limit was ∼0.12 eV. The mobility shows the dominance of lattice scattering through a deformation potential at higher temperatures than 110°K, while the observed mobility data at lower temperatures can be reasonably explained by taking into account the effect of space‐charge scattering.

66 citations


Journal ArticleDOI
TL;DR: The photoluminescence studies of the carbon doped epitaxial gallium arsenide revealed that a pair of emission bands at 1.493 eV and 1.490 eV (D-A) were attributed to the carbon acceptor on arsenic site as discussed by the authors.
Abstract: The photoluminescence studies of the carbon doped epitaxial gallium arsenide revealed that a pair of emission bands at 1.493 eV (B-A) and 1.490 eV (D-A) were attributed to the carbon acceptor on arsenic site. The sharp doublet emission lines at 1.5127 eV and 1.4937 eV were identified with the exciton recombination bound to a neutral carbon acceptor and the two-hole transition in which the neutral carbon acceptor is left in an excited state, respectively. From the observation of these emissions, the 1S3/2 ground and 2S3/2 excited state energies of carbon acceptor were found to be 26.5 meV and 7.5 meV above the valence band edge, respectively. The results were supported by the effective mass arguments and by the dependence of the binding energy on the atomic number of impurities.

46 citations


Journal ArticleDOI
TL;DR: In this paper, a method for calculating the density of states and the effective mass of a model of an electron in a completely random system containing dense and weak scatterers is presented.
Abstract: A method for calculating the density of states and the effective mass of a model of an electron in a completely random system containing dense and weak scatterers, is presented. The scattering potential employed in the model is assumed to be a gaussian function. The technique used in the calculation is the path-integral method of Feynman applied to the polaron problem (1955). Special emphasis is devoted to the consideration of the asymptotic behaviours of the density of states m(E) and the effective mass m*, for two limiting values of the correlation length L. Some improvements upon the method as well as an extension to a real physical system are discussed.

43 citations


Journal ArticleDOI
TL;DR: In this paper, the ground state energy of two-dimensional electron-hole metallic liquid is calculated with use of the generalized random phase approximation of Hubbard, and the following two cases are treated to investigate effects of dimensionality and many-valley structure: (i) the system with a single extremum is conduction and valence bands.
Abstract: The ground state energy of two-dimensional electron-hole metallic liquid is calculated with use of the generalized random phase approximation of Hubbard. The following two cases are treated to investigate effects of dimensionality and many-valley structure: (i) the system with a single extremum is conduction and valence bands and (ii) the system with the many-valley structure in the conduction band. It is shown that the ground state energy of the two-dimensional system is four times larger than that of corresponding three-dimensional system in the case (i) while it becomes more than four times larger in the case (ii) where the effective mass of electrons is lighter than that of holes. A possibility of producing the electron-hole pancake in highly excited layer-type semiconductors is pointed out. The dispersion relations of two-dimensional plasmons and acoustic modes are also derived.

38 citations


Journal ArticleDOI
TL;DR: For the first time Shubnikov-de Haas oscillations have been observed in p-type inversion layers of (111) and (100) silicon field effect transistors.

Journal ArticleDOI
TL;DR: In this paper, a detailed investigation of tunneling in Pb/PbO/pb junctions has been carried out, in an attempt to independently measure several of the parameters known to enter the tunneling problem in particular, the thickness of the tunnel barrier (orthorhombic PbO thermally grown in situ in an ultraclean vacuum system) has been measured ellipsometrically.
Abstract: A detailed investigation of tunneling in Pb/PbO/Pb junctions has been carried out, in an attempt to independently measure several of the parameters known to enter the tunneling problem In particular, the thickness of the tunnel barrier (orthorhombic PbO thermally grown in situ in an ultraclean vacuum system) has been measured ellipsometrically, and barrier heights of 115 ± 015 eV at both metal‐oxide interfaces have been deduced from Fowler‐Nordheim plots and logarithmic conductivity measurements The junctions are of high quality (less than 01% nontunneling currents) and cover a Josephson current density range of from 10−4 to 103A/cm2 From the dependence of the current density on the barrier thickness, an effective mass ratio, m*/m of 05 ± 01 has been deduced for electrons in the barrier Comparison of experimental results with the tunneling theory shows that to obtain an agreement between them, image‐force corrections must be neglected Reasonable quantitative agreement has been obtained with a small correction of 4–5 A to the ellipsometric thickness values in the range 19–31 A; no other adjustments are found necessary This discrepancy might be attributed to a difference between ellipsometric and tunneling thickness values


Journal ArticleDOI
G. Kalman1
TL;DR: In this article, a high-density fermion gas interacting through a scalar field is studied in the relativistic Hartree approximation, as a model for superhigh-density astrophysical systems.
Abstract: A high-density fermion gas interacting through a scalar field is studied in the relativistic Hartree approximation, as a model for superhigh-density astrophysical systems The Hartree quasiparticle states are the superposition of positive- and negative-energy states and can be constructed by a Bogoliubov-type canonical transformation The resulting effective mass is strongly field-dependent, and approaches 0 as the density increases into the ultrarelativistic domain The ensuing equation of state exhibits a phase transition and a bound state in the intermediate-density range, but becomes perfect-gas-like at high densities There is no collapse, and stronger coupling enhances the perfect-gas-like behavior An alternate picture is provided by considering the fermion gas in the background of zero-momentum bosons Numerical comparisons with existing scalar-meson coupling data are provided, with emphasis on regions of neutron-star densities

Journal ArticleDOI
TL;DR: In this article, the photocurrent kinetic response and the optical absorption coefficient for Bi12SiO20 in the optical range 1.0-2.0 eV were derived from the trap-filled spectral response.
Abstract: The photocurrent kinetic response and the photocurrent spectral response at 300 K are reported for Bi12SiO20 in the optical range 1.0–2.0 eV. In this range trap occupancy dominates the response. The kinetic response of the transient‐trap‐filled photocurrent provides values of the electron trap density and the optical absorption coefficient for the photoionization of the electron trap. The optical ionization energies of the traps are provided from the trap‐filled spectral response. Combining these quantities with previously determined thermal ionization energies of the electron traps provides a value for the electron effective mass of m*=14 m and a value for the effective density of states in the conduction band of Nc=1×1017T3/2. Using this value for the effective mass, an optical absorption coefficient for the photoionization process is calculated, and found to be in good agreement with the experimentally observed value.

Journal ArticleDOI
TL;DR: In this article, the electronic energy-band structure of molybdenum has been calculated by means of the relativistic augmented-plane-wave method applied to the overlapping charge-density model.
Abstract: The electronic energy-band structure of molybdenum has been calculated by means of the relativistic augmented-plane-wave method applied to the overlapping charge-density model. Full Slater exchange was employed. Calculations of extremal calipers, extremal cross-sectional areas, and cyclotron effective masses for the magnetic field along symmetry directions are reported and compared with experimental data where available. Comparison of the theoretical and experimental cyclotron-mass data indicate an anisotropic electron-phonon mass enhancement of approximately 0.33, which is smaller than the McMillan value of 0.41.

Journal ArticleDOI
TL;DR: The conduction-band and valence-band edges in InSb-As, InGaAs, and In-GaSb with spin-orbit splitting removed are calculated as a function of concentration as discussed by the authors.
Abstract: The conduction-band and valence-band edges in InSb-As, In-GaAs, and In-GaSb with spin-orbit splitting removed are calculated as a function of concentration. A two-band Kane model modified by a diagonal self-energy describing the intraband alloy scattering is used. Random strains decrease the band gap and increase the Kane formula mass. Experimental agreement is good. The spin-orbit splitting at $\ensuremath{\Gamma}$ predicted for InSb-As disagrees with experiment. A proper treatment of alloy scattering does not appreciably alter the determination of the effective mass from transport measurements.

Journal ArticleDOI
TL;DR: In this article, the interaction of rotons is studied by a direct examination of their orbital dynamics, and the binding energy and effective mass of these states are found, but are too large to agree with experiment.
Abstract: The interaction of rotons is studied by a direct examination of their orbital dynamics. It is found that upon representing rotons as point dipoles in the superfluid, obeying the Landau dispersion relation, negative energy states occur, some of which are stable and some unstable. The binding energy and effective mass of these states are found, but are too large to agree with experiment. Improvements in the Hamiltonian are explored which recognize the actual dispersion curve as well as higher moments in the interaction. Both modifications lead to binding energy and effective mass in better agreement with experiment. Scattering is also examined, and one finds that a representative roton-roton cross section may be obtained in the dipole approximation, again using Landau dispersion. The scattering cross section is shown to be in satisfactory agreement with neutron linewidths in the roton-dominated region, as well as the roton contribution to the shear viscosity.

Journal ArticleDOI
TL;DR: The electron effective mass in indium antimonide was measured at temperatures between 4.2 and 138 K using far-infrared cyclotron resonance at magnetic fields of 14.08, 16.09, and 18.05 kOe as mentioned in this paper.
Abstract: The electron effective mass in indium antimonide was measured at temperatures between 4.2 and 138 K using far-infrared cyclotron resonance at magnetic fields of 14.08, 16.09, and 18.05 kOe. The effective mass exhibits a maximum at 55 K which is 0.4% above the mass at 4.2 K and decreases with increasing temperature above 55 K. This behavior is explained reasonably well by the temperature dependence of the dilational component of the change in energy gap between the conduction and valence bands using Kane's equation for the band-edge effective mass. There is a small discrepancy between the dilational and measured mass change. Possible causes of this discrepancy are discussed.

Journal ArticleDOI
TL;DR: In this paper, the diffusion coefficient of an exciton was determined as 1/D=1/α'T -1/2 +1/βT 1/2 exp(hν/kT)-1, where ν is the frequency of the longitudinal optical phonon.
Abstract: Fluorescence decay times of naphthalene crystals were observed pulsively and their temperature dependence was analyzed with a mechanism of violated forbidden transition by molecular vibration. Fluorescence decay times of anthracene and naphthacene doped crystals were also observed by a pulsive method and the probabilities of energy transfer from singlet excitons to doped acceptors were observed. The probabilities of energy transfer were analyzed with a model that diffusing excitons transfer their energy to acceptors by dipole-dipole interactions. From the temperature dependence of the probabilities the diffusion coefficient D of an exciton was determined as 1/D=1/α'T -1/2 +1/βT 1/2 exp(hν/kT)-1, where ν is the frequency of the longitudinal optical phonon. This result means that the transport effective mass of exciton is constant in the exciton band of a naphthalene crystal. Above 250 K, the temperature dependence of energy transfer was analyzed with a thermal activation process of the excited acceptor by ...

Journal ArticleDOI
TL;DR: Theoretical capacitance and derivative of capacitance curves for an MIS structure with a semiconductor having a nonparabolic conduction band and a parabolic valence band are calculated for single level trap, uniform and nonuniform surface state distributions in this paper.
Abstract: Theoretical capacitance ( C - V ) and derivative of capacitance ( C ′- V ) curves for an MIS structure with a semiconductor having a nonparabolic conduction band and a parabolic valence band are calculated for single level trap, uniform and nonuniform surface state distributions. The Kane model is used to describe the nonparabolic conduction band. The effects of varying the hole effective mass, Kane matrix element, temperature, surface state densities (both donor and acceptor types), and the degeneracy factors for the surface states is examined. The computed results are based on Hg 0·8 Cd 0·2 TeZnS device parameters.

Journal ArticleDOI
TL;DR: The results of the measurements of magnetic susceptibility, Hall effect, and resistivity of the p-type Pb1−xSnxTe solid solutions with x = 011 to 031 and a hole concentration of (31 to 79) × 1019 cm−3 are given as discussed by the authors.
Abstract: The results of the measurements of magnetic susceptibility, Hall effect, and resistivity of the p-type Pb1−xSnxTe solid solutions with x = 011 to 031 and a hole concentration of (31 to 79) × 1019 cm−3 are given The magnetic susceptibility was measured in a temperature range of 78 to 450 °K, the Hall effect and resistivity in a range 42 to 450 °K At T > 80 °K the Hall coefficient essentially increases with temperature, which can be explained by the presence of light and heavy hole bands The temperature dependence of the magnetic susceptibility shows that the latter is paramagnetic for the holes, and the Pb1−xSnxTe valence band has a complex structure Near T = 300 °K the temperature dependence of the magnetic susceptibility has peculiarities It is supposed that the latter are connected with the conversion of the g-factor to zero when the hole effective mass increases with temperature [Russian Text Ignored]

Journal ArticleDOI
TL;DR: In this article, the authors proposed that the origin of the mass is an instability of the equally-spaced layer arrangement giving rise to a distorted form with alternate layers displaced in the axial direction.
Abstract: In the layer structure MoS2, the oscillatory inter-band magneto-optic absorption has revealed a mass ratio of the order of 0.01. Theory is presented to show that this mass may be associated with the H-point of the Brillouin zone. Moreover, it is proposed that the origin of the mass is an instability of the equally-spaced layer arrangement giving rise to a distorted form with alternate layers displaced in the axial direction.

Journal ArticleDOI
TL;DR: In this article, the effect of the quantization of the electron energy levels in a strong magnetic field on the "electron-diffusion" contribution, S e, of the transverse thermoelectric power of a high-purity isotropic semiconductor (n -type gallium arsenide GaAs) in the extreme quantum limit, when all the carriers in the conduction band are in the lowest Landau level, was studied.

Journal ArticleDOI
TL;DR: In this paper, the specific heat of an electron fluid is determined for low but nonzero temperature and for high density based on the first and second-order exchange graphs and the ring diagrams.

Journal ArticleDOI
TL;DR: In this article, transmission and reflection measurements over the frequency range 17-200 cm −1 were made on GaAs with electron concentrations of 1·0 and 4·9 × 10 16 cm −3.

Journal ArticleDOI
TL;DR: In this article, a microwave photocreated cyclotron resonance signal is observed in p -type GaSb in the temperature range 1 −30 K. The problem of a surface effect on the measured peak position, reported for the first time is avoided by bulk carrier creation.

Journal ArticleDOI
TL;DR: In the analysis of cyclotron resonance experiments with GaAs, the free-electron terms must not be neglected as mentioned in this paper, and when this term is correctly included in the equations, excellent agreement is found among data from different experiments.
Abstract: In the analysis of cyclotron resonance experiments with GaAs, the free-electron terms must not be neglected. When this term is correctly included in the equations, excellent agreement is found among data from different experiments.

Book ChapterDOI
01 Jan 1974
TL;DR: In this paper, the concept of effective mass was discussed in the theory of impurity states in semiconductors and it was shown that rigorous calculations may be interpreted in terms of an effective mass which is either smaller than m* or negative, but not equal to mo.
Abstract: In this paper we first discuss the effective-mass concept in the theory of impurity states in semiconductors. We show that one cannot be justified in replacing m by the free-electron mass mo for either shallow or deep levels. Instead, we show that rigorous calculations may be interpreted in terms of an effective mass which is either smaller than m* or negative, but not equal to mo. Finally, we report results of new calculations of binding energies using model potentials and compare with our previous results obtained with first-principles pseudopotentials.

Journal ArticleDOI
TL;DR: Very low frequency (∼10-1 Hz) regular current oscillations may be induced in iodine-doped polyethylene films when subjected to electric fields in excess of about 3 × 107 V m −1.
Abstract: Very low frequency (∼10–1 Hz) regular current oscillations may be induced in iodine-doped polyethylene films when subjected to electric fields in excess of about 3 × 107 V m–1. The oscillations are similar whether iodine is introduced from aqueous KI electrodes or from the dry vapour. The frequency depends on film thickness and iodine concentration and has an activation energy of ∼1.2 eV. Most significantly, it decreases with increasing field suggesting that space charge domains are propagating in the films encouraged by a negative differential charge carrier mobility-field characteristic. This is confirmed by direct measurement. The acceptor action of iodine probably generates mobile electron vacancies in the polymer chains, the effective mass of which increases with field to give the negative characteristic.