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

GaAs, AlAs, and AlxGa1−xAs: Material parameters for use in research and device applications

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

Hybrid Fock exchange/density functional theory functionals have shown to be very successful in describing a wide range of molecular properties. For periodic systems, however, the long-range nature of the Fock exchange interaction and the resultant large computational requirements present a major drawback. This is especially true for metallic systems, which require a dense Brillouin zone sampling. Recently, a new hybrid functional [HSE03, J. Heyd, G. E. Scuseria, and M. Ernzerhof, J. Chem. Phys. 118, 8207 (2003)] that addresses this problem within the context of methods that evaluate the Fock exchange in real space was introduced. We discuss the advantages the HSE03 functional brings to methods that rely on a reciprocal space description of the Fock exchange interaction, e.g., all methods that use plane wave basis sets. Furthermore, we present a detailed comparison of the performance of the HSE03 and PBE0 functionals for a set of archetypical solid state systems by calculating lattice parameters, bulk moduli, heats of formation, and band gaps. The results indicate that the hybrid functionals indeed often improve the description of these properties, but in several cases the results are not yet on par with standard gradient corrected functionals. This concerns in particular metallic systems for which the bandwidth and exchange splitting are seriously overestimated.

Screened hybrid density functionals applied to solids

The electron-phonon interaction in solids is important for many interesting properties of solids, among them the critical temperature of phonon-mediated superconductors, the effective electron mass in metals and semiconductors, and the carrier dynamics in semiconductors. Modern density-functional techniques have made it possible to perform $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ calculations of the electron-phonon interaction. This review explains these techniques and discusses their applications.

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Electron-phonon interactions from first principles

: A new template synthesis strategy for preparing Cu nanoclusters within dendrimer 'nanoreactors' is demonstrated. Hydroxyl-terminated polyamidoamine (PAMAM) dendrimers of generation higher than 2 act as monodispersed templates as well as stabilizers for nanocluster synthesis. Cu(2+) ions are first quantitatively sorbed into the dendrimer via a strong coordinative interaction with interior amines and then chemically reduced to yield Cu nanoclusters. The nanoclusters are composed of a well-defined number of atoms. Importantly, cluster size can be controlled by varying the size of the host dendrimer nanoreactor (16-atom Cu cluster in G4 and 64-atom Cu cluster in G6 dendrimers). The clusters remain trapped within the dendrimers for extended periods of time, do not agglomerate, and do not precipitate. The clusters can also be oxidized to yield dendrimer-encapsulated Cu(2+).

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Preparation of Cu Nanoclusters within Dendrimer Templates

Wavelength-modulation spectra of GaAs, GaSb, InAs, InSb, Ge, and Si at 5,80, and 300\ifmmode^\circ\else\textdegree\fi{}K are presented. The spectral range extends from 1.75 to 6.0 eV. The results are compared with electroreflectance and thermoreflectance data. New structures are found in the spectra of all crystals. With the help of existing band structures of these crystals, all the reflectivity peaks can be consistently assigned to proper critical transitions between the valence and the conduction bands. Values of spin-orbit splittings at several symmetry points can be calculated. Temperature effects on the band spectra are discussed.

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Wavelength-Modulation Spectra of Some Semiconductors

https://escholarship.org/content/qt6jf7d5jd/qt6jf7d5jd.pdf?t=p0lnv5

Wavelength modulation spectra of GaAs and silicon

The wavelength modulation spectrum of Cu is presented at 7\ifmmode^\circ\else\textdegree\fi{}K in the range of $2.0l~\ensuremath{\hbar}\ensuremath{\omega}l~6.0$ eV. The band structure of Cu calculated by the empirical pseudopotential method is used to compute the imaginary part of the dielectric function ${\ensuremath{\epsilon}}_{2}(\ensuremath{\omega})$ and the logarithmic derivative of the reflectivity, $\frac{{R}^{\ensuremath{'}}(\ensuremath{\omega})}{R(\ensuremath{\omega})}$. Good agreement between theory and experiment is obtained at the absorption edge and at higher energies using the one-electron approximation if dipole matrix elements are calculated from wave functions including core contributions rather than the pseudowave functions. The transitions causing the structure in $\frac{{R}^{\ensuremath{'}}(\ensuremath{\omega})}{R(\ensuremath{\omega})}$ are identified.

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Wavelength Modulation Spectrum of Copper

Wavelength-modulation spectroscopy is used to obtain the temperature dependence of the reflectivity spectrum for GaAs. Results are given in the regions of the ${E}_{1}$ doublet and the major ${E}_{2}$ peak at 5, 80, 150, 225, and 300\ifmmode^\circ\else\textdegree\fi{}K. The theoretical temperature dependence in these regions is obtained through use of Debye-Waller factors and thermal expansion coefficients in an empirical pseudopotential calculation of the ${\ensuremath{\Lambda}}_{3}\ensuremath{-}{\ensuremath{\Lambda}}_{1}$ and ${\ensuremath{\Sigma}}_{2}\ensuremath{-}{\ensuremath{\Sigma}}_{1}$ energy splittings.

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TEMPERATURE DEPENDENCE OF THE WAVELENGTH MODULATION SPECTRA OF GaAs

A wavelength-modulation spectrometer with a spectral range of 2000-8000 A has been constructed. The system measures simultaneously the derivative spectrum and the conventional spectrum. The derivative spectrum has a sensitivity of ΔR/R ~ 10−5 and is completely free of background trouble. With proper changes in the optical components, the spectral range of the spectrometer can be extended further into the infrared and into the uv.

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Ricardo R.L. Zucca

Papers

Wavelength-Modulation Spectra of Some Semiconductors

Wavelength modulation spectra of GaAs and silicon

Wavelength Modulation Spectrum of Copper

TEMPERATURE DEPENDENCE OF THE WAVELENGTH MODULATION SPECTRA OF GaAs

Wide-range wavelength modulation spectrometer.