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Your search keyword '"S. Guézo"' showing total 3 results
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3 results on '"S. Guézo"'

1. Transverse-momentum selection rules for ballistic electrons at epitaxial metal/GaAs(001) interfaces

Author

S. Le Gall, Pascal Turban, C. Lallaizon, Philippe Schieffer, S. Di Matteo, Bruno Lépine, Guy Jézéquel, S. Guézo, Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Ballistic transport, Materials science, band structure, 02 engineering and technology, Electron, Epitaxy, 01 natural sciences, Condensed Matter::Materials Science, Ballistic conduction, 0103 physical sciences, 010306 general physics, Electronic band structure, Spectroscopy, Surface states, PACS: 73.40.-c, 73.20.At, 73.23.Ad, Electronic transport in interface structures, Condensed matter physics, business.industry, Schottky diode, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Electronic, Optical and Magnetic Materials, electron density of states, Semiconductor, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, business
Abstract

International audience; We report on ballistic electron-emission spectroscopy on high-quality Au(110)/GaAs(001) and Fe(001)/GaAs(001) Schottky contacts. For the Au(110)/GaAs(001) interface, the ballistic current is characterized by a strong electron injection in the L valley of the GaAs conduction band. This remarkable spectroscopic feature is absent for the Fe(001)/GaAs(001) interface. These observations are explained by the different electronic structures in the two metal layers, assuming conservation of the electron transverse momentum at the metal/semiconductor epitaxial interfaces. Conversely, this comparative study suggests that the technique can be used for the analysis of local electronic states propagating in the metal films.

Published
2010
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2. Spatially resolved electronic properties of MgO/GaAs(001) tunnel barrier studied by ballistic electron emission microscopy

Author

Philippe Schieffer, Claude Lallaizon, J. C. Le Breton, S. Guézo, B. Lépine, Guy Jézéquel, Pascal Turban, Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Surfaces et interfaces, Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), PNANO program from the Agence Nationale de la Recherche (MOMES project) by Région Bretagne and Rennes Métropole, Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, III-V semiconductors, Physics and Astronomy (miscellaneous), Band gap, Schottky barrier, 02 engineering and technology, Electronic structure, Electron, 01 natural sciences, epitaxial layers, Condensed Matter::Materials Science, X-ray photoelectron spectroscopy, Tunnel junction, Condensed Matter::Superconductivity, 73.40.Qv, 73.30.+y, 61.72.jd, 79.60.Jv, 73.20.Hb, 73.20.At, 0103 physical sciences, magnetic tunnelling, defect states, 010306 general physics, conduction bands, Condensed matter physics, electron microscopy, X-ray photoelectron spectra, Heterojunction, vacancies (crystal), gold, 021001 nanoscience & nanotechnology, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, gallium arsenide, magnesium compounds, MIS structures, Schottky barriers, energy gap, electron emission, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Ballistic electron emission microscopy
Abstract

International audience; The spatially resolved electronic structure of the epitaxial Au/MgO/GaAs(001) tunnel junction has been studied by ballistic electron emission microscopy. The Schottky barrier height of Au on the MgO/GaAs heterostructure is determined to be 3.90 eV, in good agreement with spatially averaged x-ray photoelectron spectroscopy measurements. Locally, two well-defined conduction channels are observed for electrons energies of 2.5 and 3.8 eV, i.e., below the conduction band minimum of the oxide layer. These conduction channels are attributed to band of defect states in the band-gap of the tunnel barrier related to oxygen vacancies in the MgO layer. These defect states are responsible for the low barrier height measured on magnetic tunnel junctions with epitaxial MgO(001) tunnel barriers.

Published
2008
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3. Studies of electrochemical surface alloying and dealloying by in situ high-speed STM.

Author

Taranovskyy A, Guézo S, Matsushima H, Gründer Y, and Magnussen OM

Abstract

The electrochemical formation and dissolution of a lead/copper surface alloy on Cu(100) in chloride-containing electrolyte solutions were studied on the atomic scale by in situ scanning tunneling microscopy with high temporal and spatial resolution. Alloy formation, induced by a negative potential sweep, starts predominantly at the Cu steps, followed by the formation of a novel transient (4 × 3) alloy phase with 0.25 ML Pb coverage, which continuously is transformed into the 0.375 ML coverage c(4 × 4) phase, observed under UHV conditions. Both of these phases consist of rows of Pb atoms embedded into the Cu surface and exhibit highly dynamic structural fluctuations on sub 100 ms time scales. Upon increasing the potential again, a second c(4 × 4) phase with a different appearance in the STM images forms, which is attributed to partial dealloying, involving desorption of Pb from energetically less favorable sites. Further dealloying results in the formation of ribbon-like structures, already reported in previous studies. These ribbons are shown to consist of Pb atoms decorating domain boundaries in the c(2 × 2) chloride adlayer, left behind on the Cu surface by the dissolving surface alloy phase. Furthermore, dynamic observations of the subsequent coarsening of the ribbon network and the attachment/detachment of isolated Pd adsorbates to the ribbons are presented. Both isolated Pb adsorbates and Pb atoms in the ribbons are proposed to be stabilized by coadsorbed Cl.

Published
2012
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