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Showing papers on "Effective mass (solid-state physics) published in 1975"


Journal ArticleDOI
TL;DR: In this paper, two donor levels, one shallow and one deep (0.35 eV), and one acceptor level at 0.15 eV are identified and the hole mobility data are best fitted with an effective mass m p ∗≅1.3m e, which can be explained by simple, two band k. p theory if the valence band has appreciable d character.

149 citations


Journal ArticleDOI
TL;DR: In this paper, the electron tunneling spectra of Pb, Mg, Au, and Ag were studied and the effect on the electronic standing-wave energies was measured.
Abstract: Periodic structure in the electron tunneling spectra of Pb, Mg, Au, and Ag has been observed. Such spectra represent in fact a direct observation of size-dependent electronic states in thin metal films. Films with thicknesses from 100 to 1000 \AA{} were studied and the effect on the electronic standing-wave energies was measured. The physical model for these effects and their observability involve the existence of so-called commensurate states. The spacing of the quantized energy levels provides a direct measurement of the electron group velocity while their location in energy determines the position of band edges and other critical energy states in the band structure of the metals. In some cases, the effective mass can also be determined. A qualitative theoretical picture is sufficient to understand all of the sailient features of the observations. A number of experiments including alloying, strain, and electric field modulation are also described.

121 citations


Journal ArticleDOI
M.J. Rice1, C. B. Duke1, Nunzio O. Lipari1
TL;DR: In this paper, a tight-binding molecular orbital model of a conducting chain of large planar organic molecules was used to show that the charge density wave state in the organic metal TTF-TCNQ is stabilized predominantly by a set of small amplitude intra molecular distortions while the condensate effective mass characterizing its dynamical properties is dominated by large amplitude inter molecular distortions.

93 citations


Journal ArticleDOI
TL;DR: In this article, the effective mass and the $g$ factor of quasiparticles near the Fermi surface of a two-dimensional electron gas are calculated in the random phase approximation and in the Hubbard approximation, and compared with the experimental results for an inversion layer on a (100) surface of silicon.
Abstract: The effective mass and the $g$ factor of quasiparticles near the Fermi surface of a two-dimensional electron gas are calculated in the random-phase approximation and in the Hubbard approximation, and are compared with the experimental results for an inversion layer on a (100) surface of silicon.

69 citations


Journal ArticleDOI
TL;DR: In this paper, the eigenfunction for the center of mass motion of a Mott-Wannier exciton in a bounded medium was determined by solving asymptotically an effective mass equation, assuming electron and hole reflect perfectly from the surface: the surface potential is taken as an infinite barrier.

66 citations


Journal ArticleDOI
W. Beckenbaugh1, Jürgen Evers1, G. Güntherodt1, E. Kaldis1, P. Wachter1 
TL;DR: In this article, the reflectivity of single crystals of Gd monochalcogenides and of LaS has been measured at 300 K in the spectral region between 0.03 and 12eV.

60 citations


Journal ArticleDOI
TL;DR: In this paper, the frequency dependence of the far-infrared cyclotron effective mass of inversion-layer electrons in a Si metal-oxide-semiconductor device has been observed for the first time.
Abstract: A marked frequency dependence of the far-infrared cyclotron effective mass of inversion-layer electrons in a Si metal-oxide-semiconductor device has been observed for the first time. A qualitative interpretation of these data in terms of electron-electron interactions is presented.

51 citations


Journal ArticleDOI
TL;DR: In this paper, the drift mobility and ratio of Hall to drift mobility are computed for the scattering of carriers by a hydrogenic neutral impurity, treated using the almost exact values of the phase shifts for scattering of electrons by neutral hydrogen scaled for the effective mass and dielectric constant of the semiconductor.
Abstract: The drift mobility and ratio of Hall to drift mobility are computed for the scattering of carriers by a hydrogenic neutral impurity. The scattering is treated using the almost exact values of the phase shifts for scattering of electrons by neutral hydrogen scaled for the effective mass and dielectric constant of the semiconductor.

47 citations


Journal ArticleDOI
TL;DR: In this paper, the conductivity spectrum was fitted using effective mass theory for excitons with asymmetric Lorentzian lineshapes, and the band gap was found to be about 14.5 eV.

43 citations


Journal ArticleDOI
TL;DR: In this paper, the interaction between a dense fermion medium and a scalar-meson field is studied and a variational formalism involving only two-line irreducible diagrams is developed.
Abstract: The interaction between a dense fermion medium and a scalar-meson field is studied. It is shown that in the quasiclassical approximation, independently of the details of the theory, at low fermion density the lowest energy state is normal (i.e., effective fermion mass ${m}_{\mathrm{eff}}\ensuremath{\cong}\mathrm{free} \mathrm{mass}$, but at high density the state is abnormal (i.e., ${m}_{\mathrm{eff}}\ensuremath{\cong}0$). The nature of the transition is analyzed at zero and low temperatures. Our main concern is to examine the problem of quantum fluctuation. Both the one- and two-loop diagrams are calculated. By developing a variational formalism involving only two-line irreducible diagrams, we derive a suitable high-density expansion for the energy. The quasiclassical solution emerges as the lowest-order term in this expansion. Therefore, when the expansion is valid, the overall description of the transition given by the quasiclassical solution remains correct with the inclusion of quantum corrections.

42 citations



Journal ArticleDOI
TL;DR: In this article, the Coulomb energy of a low-density free-electron gas (jellium) in a uniform magnetic field is calculated and the critical densities for free electrons in astrophysical situations and for electrons of low effective mass in semiconductors are derived.
Abstract: The criteria for the stabilization of a condensed Wigner phase are re-examined for a low-density free-electron gas (jellium) in a uniform magnetic field. By a new calculation of the Coulomb energy it is shown that below a critical density the lowest energy state has electrons in cigar-shaped charge distributions arranged on an elongated body-centred tetragonal lattice. The critical densities are computed as functions of magnetic-field strength for free electrons in astrophysical situations and for electrons of low effective mass in semiconductors. In the latter case, the results can be used to give a satisfactory interpretation of experimental results in heavily compensated InSb.

Journal ArticleDOI
TL;DR: In this article, all electron energy band structure was reported for an infinite one-dimensional model of polysulfur nitride, (SN) x, using the ab initio LCAO Hartree-Fock method.

Journal ArticleDOI
TL;DR: In this paper, the Longitudinal magnetoresistance in the Extreme Quantum Limit (kBT) was calculated for a nondegenerate n-type InSb sample at low temperatures when the dominant energy and momentum loss mechanisms are the el-acoustic phonon and the elionized impurity interactions.

Journal ArticleDOI
TL;DR: Shallow impurity state wave functions are derived for both a coulomb and δ-function binding potential within the effective mass formalism of Kohn in this article, along with the Bloch functions of a perfect crystal are then used to obtain analytic expressions for photon spectral absorption cross-sections, thermal photon excitation rates, and carrier radiative capture crosssections into the shallow centers.
Abstract: Shallow impurity state wave functions are derived for both a coulomb and δ-function binding potential within the effective mass formalism of Kohn. These wave functions, along with the Bloch functions of a perfect crystal are then used to obtain analytic expressions for photon spectral absorption cross-sections, thermal photon excitation rates, and carrier radiative capture cross-sections into the shallow centers. The calculated absorption cross-sections are in satisfactory agreement with both magnitude and spectral shape of experimentally measured cross-sections. The absorption cross-sections are such as to make the centers very sensitive to thermal photon excitation over a wide range of temperatures or center ionization energies. Finally, it is shown that radiative carrier trapping is normally negligible for shallow centers.


Journal ArticleDOI
TL;DR: In this article, the absorption coefficient of GaSe at the photon energy range 1.94 to 2.64eV and at pressures between 1 bar and 12 kbar are investigated at 295°K.
Abstract: The spectra of the absorption coefficient (α) of GaSe at the photon energy range 1.94 to 2.64eV and at pressures between 1 bar and 12 kbar are investigated at 295°K. Data at 1 to 4360 bar confirm that the edge exciton of GaSe is the direct allowed one. The pressure coefficient of the band gap (dEg/dP = −6.2 × 10−6eV bar−1), one of the Rydberg exciton constant (dR/dP = −0.6 × 10−6eV bar−1), and one of the exciton effective mass [(1/μ) (dμ/dP) = −2.4 × 10−5 bar−1] are approximately determined. It is supposed that two interband exciton transitions at 2.001 and 3.25eV give the contribution into the α spectrum above 2.1eV. The assignment of these transitions is discussed in connection with the band structure calculation of Schluter. At 5280 bar a discontinuous jump of the absorption edge shape is observed for GaSe, with a change of the sign and a value for dEg/dP of +2.0 × 10−6eV bar−1 within the range of 5280 to 11780 bar. This effect is interpreted as the transformation of one GaSe polytype into another, i.e. as a possible phase transformation close to that of second kind. [Russian Text Ignored]

Journal ArticleDOI
TL;DR: In this article, the first cyclotron resonance in n-type GaP was reported, where the electrons were thermally excited at a temperature of 100 K and the resonance was observed at submillimetre wavelengths (337 μm).

Journal ArticleDOI
TL;DR: In this article, the authors measured the momentum distribution of photon pairs from positrons annihilating in lithium, sodium, potassium, and rubidium over a wide temperature range, and analyzed the momentum dependence of the enhancement factor, positron effective mass, and positron minimum energy in these metals.
Abstract: The momentum distribution of photon pairs from positrons annihilating in lithium, sodium, potassium, and rubidium has been measured over a wide temperature range. The results were analyzed to yield the momentum dependence of the enhancement factor, positron effective mass, and positron minimum energy in these metals. The annihilation rate at the Fermi momentum was found to be considerably higher than that at zero momentum. The magnitude of this momentum dependence of enhancement factor as well as its variation with the electron density are in good quantitative agreement with the many-body theoretical calculations. Assuming free-particle behavior, the positron effective mass has been determined to be approximately 1.8m in lithium and sodium, 2.1m in potassium, and 2.3 m in rubidium. Using a more realistic momentum distribution for the positron, which includes the positron-phonon interaction, the effective mass observed for sodium would be about 1.4 to 1.6 in fair agreement with a calculation yielding 1.2. The thermalization of positrons was observed to be complete before annihilation down to--for example in Na--160m/m*$sup 0$K. Below this temperature positrons seem to annihilate with certain minimum effective temperatures or minimum energies. These results are compared with theoretical calculations of the thermalization time of positrons in metals.

Journal ArticleDOI
TL;DR: In this paper, the intrinsic carrier concentration in Si and Ge is theoretically investigated using a detailed energy band model which includes nonparabolic effects of both the conduction and valence bands.
Abstract: The intrinsic carrier concentration in Si and Ge is theoretically investigated using a detailed energy band model which includes nonparabolic effects of both the conduction and valence bands The comparison of the theoretical results with existing experiments provides a sensitive check on the temperature dependence of the density-of-states effective mass of different bands Predominance of nonparabolic effects of valence over conduction band have been found for both elements, with particular relevance for Si

Journal ArticleDOI
TL;DR: In this paper, three phonon assisted indirect transition edges are newly found at 4.2 K, and the structures associated with direct transitions to the 1s state and higher exciton states are observable up to room temperature.
Abstract: The wavelength derivative absorption spectra of Cu 2 O have been measured in the energy regions of the yellow and green exciton series over a wide temperature range. Three phonon assisted indirect transition edges are newly found at 4.2 K, and the structures associated with direct transitions to the 1s state and the higher exciton states are observable up to room temperature. By analysing the impurity associated transition and using the Rydberg constants for both the yellow and the green exciton series, we determine the effective mass of the electron in the conduction band and those of the holes in the valence bands to be m e * ≃0.99 m 0 , m l h * ≃0.64 m 0 (light hole) and m h h * ≃1.40 m 0 (heavy hole).

Journal ArticleDOI
TL;DR: In this article, a new energy band model is proposed to include a small indirect gap comparable to the binding energy of direct excitons, which can explain the break-down of the Lyddane-Sachs-Teller (LST) relation and the compressibility anomaly for CuCl.
Abstract: To explain the break-down of the Lyddane-Sachs-Teller (LST) relation and the compressibility anomaly for CuCl a new energy band model is proposed to include a small indirect gap comparable to the binding energy of direct excitons. It is found for such a model that the condensation of excitons can result in the break-down of the LST relation as well as a number of other anomalies of properties, i.e. CuCl is a high-temperature excitonic dielectric with an effective mass ratio mh/mc ≈ 102 of electrons and holes. It is also shown that high pressure can induce a possible excitonic dielectric-superconductor phase transition. [Russian Text Ignored]

Journal ArticleDOI
TL;DR: In this article, the effective mass of a quasiparticle at the Fermi surface is given by the Fourier coefficient of the Landau-Fermi-liquid interaction function.
Abstract: The effective mass of a quasiparticle at the Fermi surface is given by ${m}^{*}=m(1+{A}_{1})$, where ${A}_{1}$ is a Fourier coefficient of the Landau Fermi-liquid interaction function. Three different methods of evaluating the Landau interaction function are investigated and compared with experiment.

Journal ArticleDOI
TL;DR: In this article, the effective unscreened interaction between a pair of electrons in the inversion layer of an MIS structure was estimated by using classical electrostatics together with a knowledge of the quantum mechanical wave function of the INversion layer electrons.

Book ChapterDOI
TL;DR: In this paper, the authors presented the intraband magneto-optical studies of semiconductors in the far infrared and found that the energy separation between two excited electronic states is made equal to the phonon energy, while the initial state of the optical transition lies on a third level.
Abstract: Publisher Summary This chapter presents the intraband magneto-optical studies of semiconductors in the far infrared The electronic energy levels of isolated impurities in semiconductors can frequently be described quite accurately in the effective mass approximation A convenient parameter that characterizes the relative strength of the magnetic field is the ratio of free electron zero-point energy in the magnetic field to the effective Coulomb binding energy The correspondence problem, the extension of the effective mass theory to include nonparabolicity and degenerate bands, the problem of central cell corrections, and the breakdown of the effective mass theory for deep impurities are examined It is found that although donor impurities in InSb and GaAs have yielded the most precise information concerning hydrogenic energy levels in a magnetic field, a number of other materials have revealed similar, less detailed features The interaction of free and bound carriers with collective excitations is elaborated It is found that in this case, the energy separation between two excited electronic states is made equal to the phonon energy, while the initial state of the optical transition lies on a third level and terminates on the upper level of the pair of excited states

Journal ArticleDOI
TL;DR: In this article, the validity of the binary collision approximation when low energy inert gas ions are scattered from the surface of a copper target was investigated, and it was found that no evidence of an increased effective mass of the target atoms was found.

Journal ArticleDOI
TL;DR: In this paper, the dielectric constants and dc resistivities of Ag-rich alloys, AgTi, AgV, AgCr, AgMn, AgFe, AgCo, and AgNi are measured at room temperature and in the range of solute concentration, 0.2 to 15 at%.
Abstract: The dielectric constants and the dc resistivities of Ag-rich alloys, AgTi, AgV, AgCr, AgMn, AgFe, AgCo, and AgNi are measured at room temperature and in the range of solute concentration, 0.2 to 15 at%. The samples are prepared by simultaneous deposition method. The dependence of the impurity resistivity on the solute metals is in qualitative agreement with the results for Au- and Cu-matrix. The collision frequency, and the ratio of the density of conduction electrons to the optical effective mass vary with solute metals in the similar way to the impurity resistivity. The distribution of the density of the virtual bound states is given. The result is discussed on the basis of the Anderson model.

Journal ArticleDOI
TL;DR: In this article, a combination of crystal momentum representation and effective mass theory is used from which results that within the one-band approximation a magnetic field normal to the Si surface and the electric gate field act upon the electrons independently from each other.
Abstract: The experimentally observed removal of valley degeneracy along the (100)-axis in the surface quantum states of Silicon MOSFETS is explained as an effect due to the electric field and spin-orbit interaction. A combination of crystal momentum representation and effective mass theory is used from which results that within the one-band approximation a magnetic field normal to the Si surface and the electric gate field act upon the electrons independently from each other.

Journal ArticleDOI
TL;DR: In this article, the ground state energy and effective mass of the exterior surface polaron as a function of the surface coupling constant were derived for a special case of the coupling constant.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the variation with magnetic field and temperature of the amplitude of giant quantum oscillations in the thermopower of aluminum from 1.7 to 4.8K in fields up to 21 kG.
Abstract: The authors have measured the variation with magnetic field and temperature of the amplitude of giant quantum oscillations in the thermopower of aluminum from 1.7 to 4.8K in fields up to 21 kG. The field and temperature variations are dominated by a term exponential in the ratio m*(T+TD)/H. Analysis using the de Haas-van Alphen procedure for determining effective masses and Dingle temperatures yields m*=(0.093 +or-0.01)me and TD approximately=1-4K. This value for m* agrees with the value obtained from de Haas-van Alphen measurements for the same electron orbit, and corresponds to a phonon-enhancement of approximately 40%.