Publications (7)9.92 Total impact

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    ABSTRACT: The diagonal component of the thermoelectric power in GaInAsInP, GaInAsAlInAs and GaAsGaAlAs heterojunctions and a GaAsGaAlAs superlattice has been studied as a function of magnetic field and temperature. In high magnetic fields, the thermopower shows oscillations proportional to the resistivity oscillations, including features due to spin splittings and the occupation of two electric subbands. The peak values of the thermopower in the GaAsGaAlAs superlattice are almost independent of temperature and close to the theoretical predictions. In contrast, the peak thermopowers measured in the heterojunctions are lower than predicted by factors of between 2 and 50, and decrease with increasing temperature.
    No preview · Article · Apr 1986 · Surface Science Letters
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    ABSTRACT: We report measurements of the diagonal component of the thermoelectric power in a superlattice and a heterojunction of GaAs and GaAlAs. The qualitative variation of the thermopower with magnetic field is in agreement with both theoretical studies and previous experimental measurements. Quantitatively, the behaviour of the superlattice agrees with calculations for an ideal two-dimensional system, but both the magnitude and temperature dependence of the thermopower in the heterojunctions cannot be explained by existing theories.
    No preview · Article · Feb 1986 · Solid State Communications
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    ABSTRACT: The evolution of fractionally quantised states has been studied in a GaAsGaAlAs heterojunction as a function of electron concentration at very low temperatures using magnetic fields up to 16T. The electron concentration was progressively increased by the use of the persistent photoconductivity effect, and it was found that the fractionally quantised states at occupancies of became much more pronounced. The state gave only a weak resistivity minimum and no Hall plateau at the highest concentration studied (4.6×1011cm−2), in contrast to the state, for which a wide Hall plateau and a deep resistivity minimum were observed.
    No preview · Article · Oct 1985 · Solid State Communications
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    ABSTRACT: Low‐temperature photoluminescence (PL) measurements have been performed on several molecular‐beam epitaxial high‐quality GaAs layers showing varied electrical characteristics (nominally undoped and intentionally doped n or p type). This work is carried out with a view to investigate the influence of the centers responsible for the defect–bound‐exciton emissions (d,x) on the electrical properties of the layers. After a systematic study of the luminescence properties of the d,x emissions as a function of the electrical nature (doped n or p type), residual p doping level, PL excitation intensity, and sample temperature, we came to the following conclusion: In addition to the prominent residual carbon acceptors, at least a part of p conduction in nominally undoped p‐type layers could come from the centers responsible for the d,x emission at 1.5109±0.0003 eV. This suggestion is tentatively ascertained by detecting an acceptor emission at ∼1.496±0.001 eV, shallower than the carbon acceptor about 3 meV. All these results in addition to those related to the detection of deeper acceptors in the spectral range 1.46–1.49 eV are presented and discussed.
    No preview · Article · Feb 1985 · Journal of Applied Physics
  • F. Alexandre · J.M. Masson · G. Post · A. Scavennec
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    ABSTRACT: Metal/insulator/semiconductor (MIS) structures were prepared by successive growth of GaAs and AlN using molecular beam epitaxy (MBE) and reactive MBE respectively. This method is expected to prevent any oxygen contamination of the interface. The dielectric and interface properties were investigated. The AlN films showed good insulating properties with a resistivity of 1014 Ω cm and a breakdown field of 3MV cm−1. Although strong Fermi level pinning is observed in the capacitance-voltage characteristics, this technique appears quite promising for the realization of high quality insulator/semiconductor devices on III–V compounds.
    No preview · Article · Dec 1982 · Thin Solid Films
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    F. Alexandre · N. Duhamel · P. Ossart · J. M. Masson · C. Meillerat

    Preview · Article · Dec 1982 · Le Journal de Physique Colloques
  • F. Alexandre · C. Raisin · M. I. Abdalla · A. Brenac · J. M. Masson
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    ABSTRACT: Intentional perturbations applied to the growth parameters of Sn‐doped GaAs layers grown by molecular beam epitaxy have been performed in order to investigate the tin incorporation mechanism. The start, the interruption, and the end of growth as well as a variation of fluxes or substrate temperature have been studied, using either the Auger electron spectroscopy (AES) measurement of tin accumulation on the surface, or C‐V derived free‐carrier concentration profile versus any of these growth parameters. The theoretical model proposed by Wood and Joyce, based on a time‐delayed incorporation mechanism, has been found to fit the observed results, especially for As‐rich surface, provided that an incorporation mechanism of second order is assumed. For Ga‐rich conditions (T s ≳580 °C), a new result has been recognized, i.e., a significant reduction of carrier concentration as T s is increased. The assumption of a partially acceptor nature of tin incident atoms under these growth conditions does not seem to fully explain this result. On the other hand, this may be better understood assuming a certain amount of tin atoms being re‐evaporated in the high substrate temperature range. This behavior induces a temporarily weaker accumulation at the surface, and hence a relatively smaller incorporation rate.
    No preview · Article · Sep 1980 · Journal of Applied Physics