The fundamental absorption edge of AlAs and AlP
TL;DR: In this paper, the fundamental absorption edge of AlAs and AlP was investigated by optical transmission measurements from 2° to 300°K, and the absorption edge structure in AlAs is consistent with the conduction band minima at or near X.
About: This article is published in Solid State Communications.The article was published on 1970-05-01. It has received 89 citations till now. The article focuses on the topics: Absorption edge & Exciton.
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TL;DR: In this article, singlecrystal layers of AlN have been grown on sapphire substrates between 1000 and 1100 °C by vapor phase reaction of aluminum chlorides with ammonia, and the purity, color, crystallinity, growth morphology, and electrical resistivity of the epitaxial layers have been investigated.
Abstract: Single‐crystal layers of AlN have been grown on sapphire substrates between 1000 and 1100 °C by vapor‐phase reaction of aluminum chlorides with ammonia. The purity, color, crystallinity, growth morphology, and electrical resistivity of the epitaxial layers have been investigated. Infrared specular reflection measurements showed the presence of an appreciable strain at the AlN‐sapphire epitaxy interface. Optical absorption data strongly suggest the AlN is a direct band‐gap material with a value of about 6.2 eV at room temperature.
525 citations
TL;DR: In this article, a detailed discussion of spectral features of the photoluminescence spectra of undoped, p−doped and n−doping AlxGa1−xAs (0≤x≤1) alloys is given.
Abstract: A thorough discussion of the various features of the photoluminescence spectra of undoped, p‐doped and n‐doped AlxGa1−xAs (0≤x≤1) alloys is given. This review covers spectral features in the energy region ranging from the energy band gap down to ≂0.8 eV, doping densities from isolated impurities to strongly interacting impurities (heavy‐doping effects) and lattice temperatures from 2 to 300 K. The relevance of photoluminescence as a simple but very powerful characterization technique is stressed also in comparison with other experimental methods. The most recent determinations of the Al concentration dependence of some physical properties of the alloy (energy gaps, carrier effective masses, dielectric constants, phonon energies, donor and acceptor binding energies, etc.) are given. The main physical mechanisms of the radiative recombination process in semiconductors are summarized with particular emphasis on the experimental data available for AlxGa1−xAs. The effects of the nature of the band gap (direct ...
440 citations
TL;DR: In this article, optical transmission data covering the Γ15V−Γ1C absorption edge are presented, together with photoluminescence (PL) results, for AlxGa1−xAs crystals of high purity [n (293 K) <1017 cm−3] for 0
Abstract: Optical transmission data covering the Γ15V–Γ1C absorption edge are presented, together with photoluminescence (PL) results, for AlxGa1−xAs crystals of high purity [n (293 K) <1017 cm−3] for 0
172 citations
TL;DR: In this article, the long-wavelength dielectric constant with lattice vibrations neglected e∞ is determined to be 8.16 ± 0.02, and the resulting static dieectric constant e0 is 10.06 ± 0.04.
Abstract: The refractive index of AlAs at 300 °K has been measured in the 0.5‐ to 2.2‐eV range of photon energy. The long‐wavelength dielectric constant with lattice vibrations neglected e∞ is determined to be 8.16 ± 0.02, and the resulting static dielectric constant e0 is 10.06 ± 0.04.
155 citations
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TL;DR: In this paper, the intensity of optical absorption close to the edge in semiconductors is examined using band theory together with the effective-mass approximation for the excitons, and the experimental results on O and Ge are in good qualitative agreement with direct forbidden and indirect transitions, respectively.
Abstract: The intensity of optical absorption close to the edge in semiconductors is examined using band theory together with the effective-mass approximation for the excitons. Direct transitions which occur when the band extrema on either side of the forbidden gap are at the same K, give a line spectrum and a continuous absorption of characteristically different form and intensity, according as transitions between band states at the extrema are allowed or forbidden. If the extrema are at different K values, indirect transitions involving phonons occur, giving absorption proportional to ${(\ensuremath{\Delta}E)}^{\frac{1}{2}}$ for each exciton band, and to ${(\ensuremath{\Delta}E)}^{2}$ for the continuum. The experimental results on ${\mathrm{Cu}}_{2}$O and Ge are in good qualitative agreement with direct forbidden and indirect transitions, respectively.
1,488 citations
TL;DR: In this paper, the authors measured the optical absorption edge at many temperatures between 1.6 and 300\ifmmode^\circ\else\text degree\fi{}K in exceptionally perfect single crystals of gallium phosphide.
Abstract: The optical absorption edge has been measured at many temperatures between 1.6 and 300\ifmmode^\circ\else\textdegree\fi{}K in exceptionally perfect single crystals of gallium phosphide. The corresponding transitions are of the allowed indirect type and involve the creation of free excitons and electron-hole pairs. Absorption components associated with four different phonon energies have been resolved, one of which is apparently due to a two-phonon process. The energies of the three single phonons are 12.8\ifmmode\pm\else\textpm\fi{}0.5, 31.3\ifmmode\pm\else\textpm\fi{}0.5, and 46.5\ifmmode\pm\else\textpm\fi{}1.0 meV. These are thought to be the respective energies of the transverse-acoustic, longitudinal-acoustic, and transverse-optic branches of the lattice dispersion curves at the $〈100〉$-type boundaries of the reduced zone, although the longitudinal-acoustic energy is \ensuremath{\sim}10 meV larger than previous estimates for this phonon. Indirect absorption associated with the longitudinal optic phonon has not been resolved, apparently because these transitions are forbidden via the energetically favorable conduction-band minimum ${\ensuremath{\Gamma}}_{1}$. The internal binding energy of the indirect exciton is 10.0\ifmmode\pm\else\textpm\fi{}1.0 meV. Fine structure, probably associated with an excited state of the indirect exciton and also with anomalies in the combined densities of states for the exciton and the acoustical phonons, has been resolved in the low-temperature spectra. The indirect energy gap is 2.339\ifmmode\pm\else\textpm\fi{}0.002 eV at 1.6\ifmmode^\circ\else\textdegree\fi{}K and 2.259\ifmmode\pm\else\textpm\fi{}0.003 eV at 300\ifmmode^\circ\else\textdegree\fi{}K. These values are considerably larger than previous estimates, especially at 300\ifmmode^\circ\else\textdegree\fi{}K. The consequences of the larger energy gap in the quantitative analysis of donor-acceptor-pair fluorescence spectra and of the spectra of bound exitons in gallium phosphide are considered.
207 citations
IBM1
TL;DR: In this paper, the symmetry of bound electron states in GaP depends upon the choice of origin for the group operations and hence upon the location of impurity in the crystal lattice.
Abstract: We show that the symmetry of bound electron states in GaP depends upon the choice of origin for the group operations and hence upon the location of impurity in the crystal lattice. This provides an explanation of the discrepancy between the high radiative efficiency associated with group VI donors and group V isoelectronic centers and the low efficiency of group IV donors (Si) in GaP.
112 citations
TL;DR: In this article, the exciton creation in Ge and Si by indirect and direct transitions has been obtained from high resolution absorption spectra, which is interpreted as being due to the formation of excitons and free electron-hole pairs.
106 citations
TL;DR: In this article, selection rules for intervalley scattering between the lowest conduction-band minima at the Brillouin zone of a III-V semiconductor were presented for theories of the Gunn effect.
Abstract: Selection rules are presented for intervalley scattering between the lowest conduction-band minima at $\ensuremath{\Gamma}$, $X$, and $L$ in the Brillouin zone of a III-V semiconductor. These selection rules are required for theories of the Gunn effect. The two most important crystals experimentally are GaAs, where longitudinal optic phonons cause the intervalley scattering, and InP, where longitudinal acoustic phonons produce the scattering.
83 citations