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It is predicted that cesium, barium, lanthanum, and cerium are altogether one common family of nonmagnetic rare earth metals at high pressure. These 4f-band metals are superconductors with a relatively high transition temperature. The "electronic transition" of cesium at 42 kbar is believed to be closely related to the "electronic transitions" of cerium at 7 and 50 kbar. We suggest both have the same basic cause: an inherent instability of the 4f-wave function under pressure. [ABSTRACT FROM AUTHOR]

Our present theoretical understanding of vibrational properties of crystals from the microscopic Coulomb interaction between electrons and ions is surveyed. A general formulation of the influence of electronic and ionic motions on vibrational excitations of arbitrary crystals, conducting or insulating, harmonic or anharmonic, is used. Implications of the theory on structural phase transitions from a free-energy functional, in particular, for lattices with not all ions processing inversion symmetry are investigated. [ABSTRACT FROM AUTHOR]

This paper presents a review of the charge-transfer mechanisms in charge-transfer devices. Special attention is given to the similarity of the physics of the transfer processes that occur in integrated MOS bucket brigades, surface charge-coupled devices, and bulk charge-coupled devices. The results of theoretical analysis and experimental measurements are used to compare the performances expected from the mentioned devices. The comparison indicates that bulk chargecoupled devices are capable of the highest performance in terms of operating frequency and charge-transfer inefficiency at all possible levels of signal charge. [ABSTRACT FROM AUTHOR]

A survey of the present state of MOS physics and technology is given. After a short introduction into the principles governing the electrical behavior of MOS structures, technological steps and problems to fabricate the elements are discussed. The properties of the silicon surface, the Si−SiO2 interface, the oxide, and the metal electrodes are described. A special section is concerned with ion implantation used in MOS technology. In each case, device aspects are considered. [ABSTRACT FROM AUTHOR]

Recent progress in the theory of low-energy electron diffraction is reviewed. It is shown, to what extent the theory can already extract information about the structure of solid surfaces out of the experimental results. The kinematic, the multiple-scattering and the data-averaging approach are discussed. [ABSTRACT FROM AUTHOR]

In this report the results of recent investigations of clean silicon surfaces are reviewed. At the present time most of the data refer to the structural, electrical, and optical properties of (111) surfaces, probably since silicon cleaves along these planes and devices are usually fabricated with (111) oriented slices. However, recently clean (100) surfaces have also attracted interest in connection with electron emitters exhibiting "negative electron affinity". For the cleaved (111) surface the experimental results may be summarized in the attempt to give elements of a surface band structure, which can be compared to theoretical approaches using LCAO and pseudopotential methods, respectively. These surface band structure studies are based on the corresponding parameters successfully used in bulk band structure calculations. However, the exact surface atom arrangement could not be considered in these theoretical investigations, since the dynamical LEED theory has not been worked out to enable an analysis of the experimentally observed LEED data. [ABSTRACT FROM AUTHOR]

The surface electric field associated with a semiconductor inversion or accumulation layer quantizes the motion normal to the surface. The bulk energy bands split into subbands near the surface forming a two-dimensional electron (hole) gas. A self-consistent formulation of the problem is given in the form of coupled Schrödinger and Poisson equations. A review of approximate results of simple limiting cases is given. The condition of surface semiconductor layer in applied magnetic field, causing Landau levels, is discussed. The analogy of the quantum size effect in thin semiconductor films to the quantum effect in the surface layer is outlined. A number of experimental techniques, as magnetoconductivity (Shubnikov-de Haas oscillations), Hall effect, capacitance, magnetocapacitance, piezoresistance, tunneling, and photoresponse measurements were carried out to verify the surface quantization in inversion and accumulation layers of silicon and other semiconductors from the low temperature region up to room temperatures. [ABSTRACT FROM AUTHOR]

The general physics of quasi one-dimensional (1-D) systems is reviewed. Attention is focussed specifically on effects of the dimensionality which are of particular importance in 1-D partially filled bands. As examples of such effects the Peierls instability, inherent of a 1-D band conductor, the singular effect of electron correlation in the case of a half-filled 1-D band and the consequences of defects and structural disorder should be mentioned. 1-D partially filled bands are realized in two classes of materials, the organic charge transfer salts of TCNQ and the mixed valency planar (MVP) transition metal compounds. In the MVP [Pt(CN)4] salts the physics is governed by the Peierls instability with a giant Kohn anomaly as a precursor. The same picture may also apply to some of the TCNQ salts. However, it seems that in the TCNQ salts the physics greatly differs from system to system. [ABSTRACT FROM AUTHOR]

The energy distribution of electrons emitted from solids—after excitation by monochromatic X-rays or uv radiation—furnishes the binding energy of core and valence electrons. The binding energy of core electrons is correlated to the ionicity of the chemical bond. Spin-orbit and core-electron interactions may be measured. Valence band density of states have been measured for a variety of crystalline and amorphous materials. [ABSTRACT FROM AUTHOR]

The results for the ground state of a two-component plasma in highly excited indirect semiconductors are discussed. Some considerations concerning the "drop" dimension are presented, followed by a description of various scattering mechanisms (exciton-exciton, exciton-electron) and their luminescence spectra in direct materials. Furthermore, the role of the exciton-molecule in these substances is investigated. Its possible condensation and decay, as well as the relation to the exciton-exciton scattering are briefly described. [ABSTRACT FROM AUTHOR]

The results of experimental investigations on optical and electrical effects in highly excited semiconductors are summarized. In direct-gap semiconductors, exciton-exciton and exciton-electron collision processes occur. At low temperature, the formation of excitonic molecules is found. All these processes can give stimulated emission. In indirect-gap semiconductors (Ge, Si), at low temperature the condensation of the excitons into a electron-hole liquid consisting of drops of a degenerate electron-hole plasma is observed. [ABSTRACT FROM AUTHOR]

In spite of its typical quantum mechanical origin, the electron correlation in different atoms, it is possible to treat van der Waals attraction by semiclassical methods. The average electromagnetic interaction field between the electrons, which is caused by photon-exchange interaction, can be calculated from the classical Maxwell equations. The van der Waals energy results from a frequency integral over the susceptibilities of the bodies considered. The main features of the theory are discussed by means of the Schrödinger formalism, which replaces the photons by an average electrostatic field, and by calculating the possible eigenvectors of the Maxwell equations, in which the electrons are replaced by susceptibilities. Several explicity manageable cases—spheres, cylinders, and films, small and large separations, with and without retardation—are presented. Applications in the field of van der Waals crystals, polymers, colloid chemistry, and biology are discussed. [ABSTRACT FROM AUTHOR]

Examples of various types of band structure encountered in II-VI and III-V alloys and in alloys of mixtures of the two are presented and discussed in terms of the present theoretical understanding of alloy band structure. The optical measurement techniques, that have been most useful in the study of alloys are reviewed. The reasons for the special problems encountered in exploratory alloy studies, namely small samples and graded alloy composition, are discussed. Finally, examples are given of the application of III-V alloys in devices. [ABSTRACT FROM AUTHOR]

The binding energy of excitions bound to defects in semiconductors is investigated, especially for the systems: excitons bound to ionized donors, neutral donors, donor-acceptor paris, and isoelectronic impurities. The importance of electron-phonon coupling is emphasized, and some recent developments are reported. [ABSTRACT FROM AUTHOR]

This paper gives the results of recent experiments on the electrical, magnetic, optical and structural properties of layer type crystals. It deals in particular with the layer type transition metal dichalcogenides, MX2, and representative members are ZrS2, NbSe2, MoS2. These materials have been the subject of fairly intense activity during the past few years. It is argued that in NbSe2, there is a relatively narrow "d" band based on overlap of dz2 orbitals on the Nb atoms lying in the plane of the sandwich, and that it is this band which is the basis of many of the interesting physical properties, Phenomena such as excitons, screening effects, conduction in narrow "d" bands, superconductivity and the metal-insulator transtion are all encountered. Interaction of the MX2 crystals with a variety of organic and inorganic molecules and atoms can lead to quite dramatic changes in the physical properties. Long chain organic amines inserted between the MX2 layers in the van der Waal's gap can separate the layers by large distances approaching 60 Å, and the intercalated crystals still remain superconductors. These experiments, together with those in which superconductivity is found in crystals of NbSe2 a until cell in thickness (c 12 Å), suggests we may be concerned with essentially two dimensional superconductivity, but this is still an open and controversial point. [ABSTRACT FROM AUTHOR]