This review provides numerical and graphical information about many (but by no means all) of the physical and electronic properties of GaAs that are useful to those engaged in experimental research and development on this material. The emphasis is on properties of GaAs itself, and the host of effects associated with the presence of specific impurities and defects is excluded from coverage. The geometry of the sphalerite lattice and of the first Brillouin zone of reciprocal space are used to pave the way for material concerning elastic moduli, speeds of sound, and phonon dispersion curves. A section on thermal properties includes material on the phase diagram and liquidus curve, thermal expansion coefficient as a function of temperature, specific heat and equivalent Debye temperature behavior, and thermal conduction. The discussion of optical properties focusses on dispersion of the dielectric constant from low frequencies [κ0(300)=12.85] through the reststrahlen range to the intrinsic edge, and on the ass...

Semiconducting and other major properties of gallium arsenide

A theory of negative-conductance amplification and of Gunn-effect oscillation in good agreement with experimental observations is developed for "two-valley" semiconductors such as GaAs and InP. The theory is based upon a conduction-band model in which the relative populations of two valleys of vastly different mobility are determined by the average electron temperature, the latter being described by energy transport equations. Numerical computer solutions of the dynamic equations identify different modes of sample behavior and give a clear indication of the microscopic physical processes relevant to each.

Theory of negative-conductance amplification and of Gunn instabilities in "two-valley" semiconductors

A new mechanism is proposed to obtain negative differential resistance in layered heterostructures for conduction parallel to the interface. The mechanism is based on hot‐electron thermionic emission from high‐mobility GaAs into low‐mobility AlxGa1−xAs. Preliminary calculations indicate that high peak‐to‐valley ratios can be achieved. The transfer speed is estimated to be of the order of 10−11 s. We further show that the concept of hot‐electron thermionic emission can be applicable to a variety of devices.

Negative differential resistance through real‐space electron transfer

Current flow, considering a semiclassical electron--electric-field interaction and electron scattering by acoustic phonons, is studied in semiconducting zig-zag carbon nanotubes. The $\ensuremath{\pi}$-electronic band structure and the phonon spectrum of the nanotube are both calculated from graphene by the zone-folding method. Scattering rates are calculated using first-order perturbation theory and the deformation-potential approximation, while the selection rules for the electron-phonon interaction are developed based on the conservation of crystal momentum. The steady-state transport properties of electrons in small-diameter nanotubes are simulated using the Monte Carlo method. Results show negative differential mobility occurring at smaller threshold fields as the tube diameter increases. The peak drift velocity is also found to depend on the tube diameter, and reaches values as high as $5\ifmmode\times\else\texttimes\fi{}{10}^{7}\mathrm{c}\mathrm{m}/\mathrm{s}$ in the largest tube considered with a diameter of $\ensuremath{\cong}4.6\mathrm{nm}.$ The simulated low-field mobility is as large as in graphite, $\ensuremath{\cong}2\ifmmode\times\else\texttimes\fi{}{10}^{4}{\mathrm{cm}}^{2}/\mathrm{V}/\mathrm{s},$ for the larger tubes, but decreases as the tube diameter decreases.

Semiclassical transport and phonon scattering of electrons in semiconducting carbon nanotubes

The properties of hot electrons in systems where electrons and phonons experience quantum confinement are reviewed. The modifications to the behaviour of electrons and phonons brought about by confinement are described, particularly with reference to the principal scattering mechanism. The latter include the interaction with longitudinal optical phonons and plasmons, along with carrier-carrier effects. Some conflict in the literature concerning Fuchs-Kliewer polaritons is discussed. Low-temperature interactions with acoustic phonons are described. A central topic is that of energy relaxation, and the experimental and theoretical data relating to this form a large part of the review. Energy relaxation mechanisms in the femtosecond to nanosecond regimes, including intersubband and well-capture processes, are eventually summarized. An equally large section deals with hot-electron transport; in which negative differential resistance and other instabilities associated with parallel transport are discussed before turning to ballistic transport and impact ionization.

https://iopscience.iop.org/article/10.1088/0034-4885/54/2/001/pdf

Hot electrons in low-dimensional structures

In some semiconductors the conduction band system has two minima separated by only a small energy, and the lower minimum has associated with it a smaller electron effective mass than the upper minimum. At high electric fields it should be possible to transfer electrons to the upper minimum where they will have a lower mobility. The conductivity of a homogeneous crystal bar can therefore decrease as the field is increased, and it is conceivable that a differential negative resistance could be obtained. The conditions needed for obtaining negative resistance are examined, and calculations made for GaSb and semi-insulating GaAs. It appears that negative resistances should be observable in both these materials.

C. Hilsum

Papers

Transferred Electron Amplifiers and Oscillators

Transferred electron amplifiers and oscillators