Showing papers on "Effective mass (solid-state physics) published in 1985"
TL;DR: In this article, a review of the properties of the Al x Ga1−x As/GaAs heterostructure system is presented, which can be classified into sixteen groups: (1) lattice constant and crystal density, (2) melting point, (3) thermal expansion coefficient, (4), lattice dynamic properties, (5) lattices thermal properties,(6) electronic-band structure, (7) external perturbation effects on the bandgap energy, (8) effective mass, (9) deformation potential, (10) static and
Abstract: The Al x Ga1−x As/GaAs heterostructure system is potentially useful material for high‐speed digital, high‐frequency microwave, and electro‐optic device applications Even though the basic Al x Ga1−x As/GaAs heterostructure concepts are understood at this time, some practical device parameters in this system have been hampered by a lack of definite knowledge of many material parameters Recently, Blakemore has presented numerical and graphical information about many of the physical and electronic properties of GaAs [J S Blakemore, J Appl Phys 5 3, R123 (1982)] The purpose of this review is (i) to obtain and clarify all the various material parameters of Al x Ga1−x As alloy from a systematic point of view, and (ii) to present key properties of the material parameters for a variety of research works and device applications A complete set of material parameters are considered in this review for GaAs, AlAs, and Al x Ga1−x As alloys The model used is based on an interpolation scheme and, therefore, necessitates known values of the parameters for the related binaries (GaAs and AlAs) The material parameters and properties considered in the present review can be classified into sixteen groups: (1) lattice constant and crystal density, (2) melting point, (3) thermal expansion coefficient, (4) lattice dynamic properties, (5) lattice thermal properties, (6) electronic‐band structure, (7) external perturbation effects on the band‐gap energy, (8) effective mass, (9) deformation potential, (10) static and high‐frequency dielectric constants, (11) magnetic susceptibility, (12) piezoelectric constant, (13) Frohlich coupling parameter, (14) electron transport properties, (15) optical properties, and (16) photoelastic properties Of particular interest is the deviation of material parameters from linearity with respect to the AlAs mole fraction x Some material parameters, such as lattice constant, crystal density, thermal expansion coefficient, dielectric constant, and elastic constant, obey Vegard’s rule well Other parameters, eg, electronic‐band energy, lattice vibration (phonon) energy, Debye temperature, and impurity ionization energy, exhibit quadratic dependence upon the AlAs mole fraction However, some kinds of the material parameters, eg, lattice thermal conductivity, exhibit very strong nonlinearity with respect to x, which arises from the effects of alloy disorder It is found that the present model provides generally acceptable parameters in good agreement with the existing experimental data A detailed discussion is also given of the acceptability of such interpolated parameters from an aspect of solid‐state physics Key properties of the material parameters for use in research work and a variety of Al x Ga1−x As/GaAs device applications are also discussed in detail
2,671 citations
TL;DR: Measurements of the two-photon absorption coefficients beta(2) of 10 different semiconductors having band-gap energies between 1.4 and 3.7 eV find that beta( 2) varies as E(g)(-3), as predicted by theory.
Abstract: We present measurements of the two-photon absorption coefficients /2 of 10 different semiconductors having band-gap energies between 1.4 and 3.7 eV. We find that 12 varies as Eg- 3 , as predicted by theory. In addition, the absolute values of 02 agree with theory, which includes the effect of nonparabolic bands, the average difference being less than 26%. This agreement permits confident predictions of two-photon absorption coefficients of other materials at other wavelengths. The ever-increasing role of semiconductors in lightwave technology has created a pressing demand for the characterization of the nonlinear-optical properties of these materials. Semiconductors are attractive as elements in nonlinear-optical devices because of their large and potentially extremely fast optical nonlinearities. A careful study of these macroscopic nonlinearities should allow one to determine the dependence of these nonlinearities on fundamental microscopic mechanical and electronic material properties (e.g., band gap, carrier lifetime, carrier effective mass). The data base formed by this information would then allow one not only to tabulate the materials that exhibit large nonlinearities but also to predict the specific material parameters that give rise to these high nonlinearities. This predictive capability is extremely important from the standpoint of searching for materials with large nonlinearities. A study of the nonlinear-optical properties of several semiconductors is presented here, and a relationship between the two-photon absorption coefficient (/32) and other material properties is verified. Ten different materials were experimentally studied for which the incident photon energy hw is less than the direct band-gap energy Eg but greater than Eg/2, so that two-photon absorption (2PA) is allowed.' Both 1.06and 0.53-jum picosecond pulses are used in transmission experiments, similar to those used previously by Bechtel and Smith, 2 on semiconductors with Eg ranging from 1.4 to 3.7 eV. We find that 02 is given by
314 citations
TL;DR: The theoretical and experimental evidence which testifies to the existence of a strong energy dependence of this effective mass around the Fermi energy and near the nuclear surface is the central subject of the present review.
295 citations
TL;DR: In this paper, the spin split hole subband structure is calculated and the cyclotron masses as a function of magnetic field are extracted from it, and the many-body effects are important.
Abstract: The spin-split hole subband structure is calculated. From it, cyclotron masses as a function of magnetic field are extracted. Agreement with experiment is not good. We argue that many-body effects are important.
283 citations
TL;DR: In this article, a cubic rock salt structure with a lattice constant unchanged, within experimental error, from the bulk value was examined in the regime where bulk properties are not fully formed.
Abstract: Tiny single PbS crystals of ∼25 A diameter are synthesized and studied optically in low‐temperature colloidal solutions. Electron microscopic examination shows a simple cubic rock salt structure with a lattice constant unchanged, within experimental error, from the bulk value. These crystallites lack the near infrared electronic absorption characteristic of bulk PbS. The small crystallite absorbance in the visible rises more steeply than does the bulk absorbance. These results reflect electron and hole localization if one considers the variation in effective mass across the band structure. A simple discussion of localization anywhere in the Brillouin zone is given. For the first time, crystallite syntheses are carried out in solvent mixtures that form transparent glasses upon cooling. The PbS spectra are independent of temperature (at current experimental resolution) down to 130 K, in contrast to earlier results for quantum size exciton peaks in ∼20 A ZnS crystallites. Previously published observations of size dependence in the excited state electronic properties of AgI and AgBr are explained as consequences of electron and hole localization in the small crystallites. AgBr appears to be the first indirect gap semiconductor to be examined in the regime where bulk properties are not fully formed.
145 citations
TL;DR: In this paper, the effects of the electron-LO-phonon interaction effects on the electronic properties of a single two-dimensional electron layer (as occurring, for example, in artificially structured single quantum wells or heterojunctions made of III-V or II-VI semiconducting materials) are discussed theoretically.
121 citations
TL;DR: In this paper, the subband structure of a two-dimensional hole system at GaAs/AlGaAs heterojunctions and quantum wells is calculated in the selfconsistent Hartree approximation.
Abstract: The subband structure of a two-dimensional hole system at GaAs/AlGaAs heterojunctions and quantum wells is calculated in the self-consistent Hartree approximation. The subband dispersion is shown to be quite nonparabolic and anisotropic. The cyclotron effective mass is strongly dependent on the hole concentration. The spin splitting is extremely large due to the lack of inversion symmetry at single heterojunctions. Light-scattering spectra are calculated for quantum wells and the agreement with experiments is excellent for systems with low hole concentrations.
118 citations
TL;DR: In this paper, the first observation of an extremely large photocurrent amplification phenomenon at very low voltages in a superlattice of Al0.48In0.53As (35 A), grown by molecular beam epitaxy, was reported.
Abstract: We report the first observation of an extremely large photocurrent amplification phenomenon at very low voltages in a superlattice of Al0.48In0.52As (35 A)/Ga0.47In0.53As (35 A), grown by molecular beam epitaxy. Responsivities at λ=1.3 μm are as high as 4×103 A/W at 1.4 V corresponding to a current gain of 2×104. Significant gains (≂50) were obtained at voltages as low as 20 mV. The detectivity D* at λ=1.3 μm and 1‐kHz modulation frequency is 1011 (cm Hz1/2/W) at 0.2‐V bias. This effect, which represents a new quantum type photoconductivity, is caused by the large difference in the tunneling rates of electrons and holes through the superlattice barriers, associated with their large effective mass difference (effective mass filtering). Superlattice effective mass filters represent a new class of low voltage, high gain photodetectors. A unique feature, which makes them potentially extremely versatile, is the ability to tune the gain and gain‐bandwidth product over a wide range by varying the superlattice pe...
117 citations
TL;DR: In this paper, a five-level k-ensuremath{rightarrow} √ √ K √ k √ n √ N √ 1/ √ 2/n √ 3/n√ n/n/n−1/n-1/k √ p-type valence-and higher conduction-band edges were derived for conduction band electrons.
Abstract: A five-level k\ensuremath{\rightarrow}\ensuremath{\cdot}p\ensuremath{\rightarrow} theory is developed for conduction-band electrons in heterostructures. A local effective mass and a local g factor are obtained which depend on the variation of the p-type valence- and higher conduction-band edges. The effective mass and the spin splitting found in cyclotron and spin-resonance experiments are explained. A finite spin splitting is obtained at zero magnetic field and the possibility of determining the interface discontinuity from the spin splitting is discussed.
99 citations
TL;DR: In this article, the first observation of light-hole band carriers in In0.2Ga0.8As/GaAs strained-layer superlattices by direct measurements of their effective mass (m*mo=0.14) using oscillatory magnetoresistance data was reported.
Abstract: We report the first observation of light‐hole band carriers in In0.2Ga0.8As/GaAs strained‐layer superlattices by direct measurements of their effective mass (m*mo=0.14) using oscillatory magnetoresistance data. Preferential population of light‐hole states, due to splitting of the degenerate bulk valence bands by built‐in strain, allows this direct observation.
97 citations
TL;DR: In this paper, the effective mass values m ∗ t = (0.247 ± 0.011)m 0, m ∆ t ∆ ∆ l = 0.677 ± 1.015m 0 were determined for films of β-SiC grown on Si(100) surfaces previously reacted with carbon.
TL;DR: An angle-resolved photoemission investigation of the surface electronic structure of Be(0001), using synchrotron radiation, shows rapid variations caused by changes in the local electromagnetic field at the surface, which is associated with the short penetration depth of the Be surface state.
Abstract: We have performed an angle-resolved photoemission investigation, using synchrotron radiation, of the surface electronic structure of Be(0001). At normal emission we observe a surface state in the I 3 -I 4. band gap with a binding energy of 2.8+0.1 eV. Away from I it disperses parabolically towards EF with an effective mass of m*/m — 1.5. For %co &40 eV, the energy dependence of the photoexcitation cross section for this state shows rapid variations caused by changes in the local electromagnetic field at the surface. For Ace &40 eV, it shows only weak structure. This highenergy behavior is quite different from the large resonances observed for surface states on other metals and is associated with the short penetration depth of the Be surface state. The dispersion of this state is measured along I ~M and I ~E in the two-dimensional surface Brillouin zone. For a small range of k~~ around M, there is evidence for ttvo surface states in the M2 -M4 gap with binding energies of 1.8+0.1 eV and 3.0+0.1 eV.
TL;DR: In this paper, the charging characteristics of metal-nitride oxides were analyzed using a new technique of analyzing the charging properties of metal−oxide-oxide-semiconductor capacitors.
Abstract: Interface potential barrier heights for ultrathin silicon oxides (15– 44 A) on silicon and effective electron masses in some of these oxides are evaluated Evaluation is performed using a new technique of analyzing the charging characteristics of metal‐nitride‐oxide‐semiconductor capacitors Oxides thicker than 36 A have the same potential barrier heights as those for thick oxides, assuming the effective electron mass of the oxides is the same However, for oxides thinner than 31 A, the potential barrier heights decrease and the effective electron masses increase as the oxide thickness decreases These results suggest that oxides at least thicker than 36 A can be applied to metal‐oxide‐semiconductor field‐effect transistors as gate oxides
TL;DR: The magnetophonon effect arises due to resonant phonon emission or absorption by free charge carriers in a solid in a high magnetic field as mentioned in this paper, which causes resonant transitions between Landau levels at magnetic fields.
TL;DR: Nouvelles mesures de photoemission inverse pour Ag (100) : influence de l'ondulation de surface sur les etats de surface de potentiel image.
Abstract: Influence de l'ondulation de surface sur les etats de surface de potentiel image. Nouvelles mesures de photoemission inverse pour Ag (100)
TL;DR: In this article, the system of two electrons coupling with phonon fields with the use of the path integral method is studied. In particular, the condition of the formation of a bipolaron and its physical properties are investigated in detail.
Abstract: The system of two electrons coupling with phonon fields is studied with the use of the path integral method. In particular, the condition of the formation of a bipolaron and its physical properties are investigated in detail. The deformation potential interaction with acoustic phonons (the coupling constant S ac ) and the Frohlich interaction with optical phonons ( S op ) act to help the bipolaron formation against the direct Coulomb repulsion which prevents it. Usually, S ac plays a dominant role. With e ∞ / e 0 ≪1 and the optical phonon energy not so large compared with the electron band width, however, the bipolaron can be formed at large values of S op even when S ac =0. The bipolaron always has an enormous effective mass; thus it is practically localized. The mean distance between two electrons in the bipolaron is usually of the order of the interatomic distance.
TL;DR: In this article, it was shown that the binding energy of surface states is a multibranch function of the image-plane position, and that the image plane is further from the crystal edge on more loosely packed surfaces and that dynamical corrections to the image potential account for increases in the effective mass of 5%.
Abstract: We show that the binding energy of surface states is a multibranch function of the image-plane position. The states of the Rydberg series (including the conventional crystal-derived states) have a unique labeling in terms of the number of extrema in the wave function beyond the crystal edge, and the spatial extent of the image states is determined by their binding energy. In addition, we find that the image plane is further from the crystal edge on more loosely packed surfaces and that dynamical corrections to the image potential account for increases in the effective mass of 5%.
TL;DR: In this article, a simple equation of state for supernova matter is based on the compressible liquid-drop model, and the nuclei-bubbles and bubbles-nuclear matter phase transitions are handled smoothly.
IBM1
TL;DR: In this article, the first unoccupied electronic surface states on Ag(110) were discovered using k-resolved inverse photoemission, where the image and intrinsic surface states were split off from bulk bands into projected bandgaps owing to the jump of the electrostatic potential at the surface.
TL;DR: In this article, the Schrodinger equation with an effective mass was solved for a new class of angular momentum dependent potentials with varying depths and shapes, and the energy eigen, values and resonances were given in algebraic form as a function of the effective mass and depth and shape of the potential.
TL;DR: In this article, the point group symmetry of the highest valence state beyond the reduction from cubic to laminar symmetry was shown to be broken in optical emission from electrons confined in quantum wells, and the component with polarization normal to the planes was observed to be unexpectedly strong.
TL;DR: In this article, low-temperature magneto-luminescence studies on strained layer superlattices are used to determine in-plane light-hole band effective masses in both n- and p-type InGaAs/GaAs structures.
TL;DR: In this paper, the frequency and temperature-dependent cyclotron resonance in the ternary alloy GaxIn1-xAs, close to its lattice match with InP, was reported, and the band-edge effective mass was found to be 0.041 m0 for x=0.47.
Abstract: Measurements are reported of frequency- and temperature-dependent cyclotron resonance in the ternary alloy GaxIn1-xAs, close to its lattice match with InP. The band-edge effective mass is found to be 0.041 m0 for x=0.47, in agreement with earlier measurements, but it is found that the non-parabolicity of the conduction band is approximately double that expected on the basis of k.p perturbation theory. This is thought to be due to alloy disorder. Magnetophonon resonance was also observed, giving a further measurement of the effective mass, together with the first observation of two-phonon-mode behaviour in this material.
TL;DR: In this paper, the de Haas-van Alphen effect was used to compare the Fermi surface of three compounds LnB6 (Ln La, Ce and Pr) by measurement of the DEV effect.
Abstract: The Fermi surface has been compared for the three compounds LnB6 (Ln La, Ce and Pr) by measurement of the de Haas-van Alphen effect. The major part is observed to be similar in each compound, most likely consisting of X-centred ellipsoids with a total effective volume of about 1 electron per formula unit. Differences occur in the details of the shape of the FS, clearly seen for PrB6. Large effective masses, m ∗ , are observed for CeB6 and PrB6, m ∗ = 6 and about 1.8, respectively. These have to be compared with m ∗ = 6.0 for LaB6.
TL;DR: In this article, computer-simulated studies of charge-pair separation mechanisms in pentacene (Pc) crystals are presented, where both charge-separation stages are simulated in a framework of an extended Sano-Mozumder model.
TL;DR: In this paper, the dispersion relations for electron, light hole, and split-off hole subbands were obtained using the envelope function approximation taking into account band nonparabolicity.
Abstract: Nonparabolic subband structure of GaInAs‐InP quantum wells is studied theoretically. The dispersion relations for electron, light hole, and split‐off hole subbands are obtained using the envelope function approximation taking into account band nonparabolicity. Reported experimental electron effective mass values and photoluminescence energies for wide quantum wells are resonably explained by the present theory. The experimental photoluminescence energies, for the well width less than 50 A, differ significantly from the calculated results.
TL;DR: In this paper, the effect of particle-vibration coupling on a single-particle matrix element of the isoscalar Lorentz vector current in the relativistic σ-ω model was investigated.
TL;DR: In this paper, the optical reflectivity of SmB 6, YbB 12 and gold SmS has been analyzed with a Kramers-Kronig transformation, revealing a hybridization gap of 4, 7 and 6 meV, respectively, with E F in the gap.
TL;DR: In this paper, the Hartree-Fock potential with the Gogny D1 effective interaction or the Perey-Buck potential is employed to calculate the polarization and correlation contributions to the real part via the dispersion relation.