Papers by Bernard Sermage
Applied Physics Letters, 1997
Photoluminescence measurements under different excitation powers and time-resolved photoluminesce... more Photoluminescence measurements under different excitation powers and time-resolved photoluminescence experiments were carried out at low temperature on tensile strained In0.3Ga0.7As quantum wells with InGaAs barriers lattice matched to InP. Evidence of a type II recombination is found between carriers confined in the tensile strained layer and in the lattice matched one. This study allows us to propose a precise determination of the light holes band offset in the In0.3Ga0.7As/In0.53Ga0.47As system.
Nanofabrication at the “Groupement Scientifique CNET-CNRS” in Bagneux has been performed using ei... more Nanofabrication at the “Groupement Scientifique CNET-CNRS” in Bagneux has been performed using either a JEOL 5D2U e-beam pattern generator, or a modified Philips 515 scanning electron microscope. In this paper we present some of the results we obtained on the transport and optical properties of 1D an 0D structures in III–V semiconductors.
Journal of Applied Physics, 2016
The electrochemical capacitance voltage technique has been used on highly boron doped SiGe and Si... more The electrochemical capacitance voltage technique has been used on highly boron doped SiGe and Si layers. Although the boron concentration is constant over the space charge depth, the 1/C2 versus voltage curves are not linear. They indeed present a negative curvature. This can be explained by the existence of deep acceptors which ionise under a high electric field (large inverse voltage) and not at a low inverse voltage. The measured doping concentration in the electrochemical capacitance voltage increases strongly as the inverse voltage increases. Thanks to a comparison with the boron concentration measured by secondary ions mass spectrometry, we show that the relevant doping concentrations in device layers are obtained for small inverse voltage in agreement with the existence of deep acceptors. At the large inverse voltage, the measured doping can be more than twice larger than the boron concentration measured with a secondary ion mass spectroscopy.
Physica B+C, 1985
... The inverse nonradiative lifetime (1/Tnr) is given by the circles and the square (+ +o; x +o)... more ... The inverse nonradiative lifetime (1/Tnr) is given by the circles and the square (+ +o; x +o). The dashed line is an approximation of 1/Tnr. ... Lett.42 (1983) 259 3. E. Wintner and EP Ippen, Appl. Phys. Lett. 44 (1984) 999 4. EA Rezek, N. Holonyak, Jr. and BK Fuller, J. Appl. Phys. ...
Springer Proceedings in Physics, 2001
Physical Review B, 1981
We have performed resonant Brillouin scattering experiments in ZnSe in the [100]and f110]directio... more We have performed resonant Brillouin scattering experiments in ZnSe in the [100]and f110]directions. These two directions are needed to obtain the exciton-polariton dispersion curves without ambiguity. Even if only the influence of the isotropic part of the exchange interaction on heavy and light excitons is taken into account, the number of polariton branches is shown to be dependent on the wave-vector direction. However, in ZnSe a three-branchpolariton model ("quasi-isotropic" model) is enough to account for the experimental results. We obtain thus the longitudinal-transverse (triplet) splitting E"T = 1.45+0.05 meV, and the quintuplet-transverse (triplet) splitting h =-0.1+0.1 meV, and the masses of heavy and light excitons, M"and M"M"(100) = 1.11~0.1mo, M, (100) = 0.3~0.05m"M"(110)= 1.95~0.1mf), M, (110) = 0.37~0.05mo in the free-electron mass unit. These numerical values are little altered if the linear k term is taken into account.
LEOS 1992 Summer Topical Meeting Digest on Broadband Analog and Digital Optoelectronics, Optical Multiple Access Networks, Integrated Optoelectronics, and Smart Pixels
ABSTRACT
Le Journal de Physique Colloques, 1975
RQumf.-Les composes ternaires 1 structure chalcopyrite posskdent trois bandes de valence en centr... more RQumf.-Les composes ternaires 1 structure chalcopyrite posskdent trois bandes de valence en centre de zone auxquelles correspondent trois transitions (A, B et C) avec la bande de conduction. Des mesures de rtflectivite simple et modulee en longueur d'onde sur AgGaSe2 et AgGaTe2 nous ont permis de determiner la variation des Bnergies de ces trois transitions entre la temperature de I'helium liquideet la temperature ambiante. La cathodoluminescence nous a permis de verifier que la transition A correspond Q la bande interdite pour AgGaTez et de preciser son energie. Pour AgGaSez, la largeur de la bande interdite croit avec la temperature entre 5 et 95 K et decroit aux temperatures superieurcs avcc un coefficient tres faible (-1,2 X 10-4 eV/K). AgGaTez presente un comportement moins anormal. Cepcndant le coefficient de temperature au-dessus de 100 K est egalcment faible (-2 X 10-4 eV/K). Nous avons calcule l'energie du champ cristallin ACF et le couplage spin-orbite A s o a partir des energies des trois transitions B I'aide du modele quasi cubique. Dans les deux cas I A C E I cst une 10
Physical Review B, 1987
We have studied electronic properties of GaAs-A1As short-period superlattices grown by molecular-... more We have studied electronic properties of GaAs-A1As short-period superlattices grown by molecular-beam epitaxy. A direct-gap to "indirect"-gap transition has been evidenced through optical experiments on a large number of samples. It also corresponds to a type-I to type-II superlattice transition. Our results are in good agreement with an envelope-function description applied to each extremum of the host-material band structure. As a result of spatial transfer of electrons in AlAs, we have obtained an accurate value of the offset parameter AE,"/AEg 0 67.
NATO ASI Series, 1989
Picosecond and subpicosecond luminescence techniques have been used to study vertical transport i... more Picosecond and subpicosecond luminescence techniques have been used to study vertical transport in GaAs/GaAlAs superlattices. The great advantages of these techniques are the very good time resolution and the absence of processing of the sample. We describe in this revue the main results and emphasize on some of the interesting aspects of the interpretation of the results. Both electron and hole mobilities can be obtained by using different excitation densities. They are compared with theoretical estimates.
Surface Science, 1992
Luminescence, luminescence excitation as well as time resolved luminescence under resonant excita... more Luminescence, luminescence excitation as well as time resolved luminescence under resonant excitation are performed on high quality GaAs/AlAs quantum wells in order to assess the quality of the interface. The transfer from zones of a well defined thickness to zones larger by one monolayer is evidenced by selective excitation.
Superlattices and Microstructures, 1990
Abstract We have used cw photoluminescence (PL), excitation of the photoluminescence (PLE) and ti... more Abstract We have used cw photoluminescence (PL), excitation of the photoluminescence (PLE) and time-resolved photoluminescence experiments to study optical properties and vertical transport in type I GaAs A; As superlattices (SLs). The behaviour of GaAs AlAs superlattices is found to be quite comparable to that of GaAs AlGaAs superlattices.
Solid-State Electronics, 1996
Spatially or spectrally selective photoluminescence (PL) studies, as well as time-resolved PL, hi... more Spatially or spectrally selective photoluminescence (PL) studies, as well as time-resolved PL, highlight the superior intrinsic electronic properties of InAsGaAs quantum boxes (QBs) obtained by self-organized molecular beam epitaxy. A given QB displays a single PL line, with linewidth much smaller than the thermal energy kT. The emission of resonantly excited QBs is slightly Stokes shifted (0.7 meV) with respect
Solid State Communications, 1990
We show, from the photoluminescence of a GaAs-G~,~Al,,,As superlattice of period 70 A, that the l... more We show, from the photoluminescence of a GaAs-G~,~Al,,,As superlattice of period 70 A, that the localization of the electrons takes place at low field (-1 x 10" V/cm). When the localization begins, the binding energy of the heavy-hole exciton is approximately the same whether the electron wavefunction is centered on the same well as the hole or on an adjacent well. The model of eigenfunctions proposed by Bleuse et al. for superlattices under electric fteld tits our results satisfactorily. A reduction of the electric field applied to the superlattice has been obtained by using a laser beam with photon energies greater than the bandgap width of the barriers. This effect provides accurate measurements of the low field localization.
Journal of Crystal Growth, 1993
... a comparison between MBE and CBE JL Benchimol, F. Alexandre, N. Jourdan, AM Pougnet, R. Melle... more ... a comparison between MBE and CBE JL Benchimol, F. Alexandre, N. Jourdan, AM Pougnet, R. Mellet, B. Sermage, F. Heliot and C. DubonChevallier France Telecom, Centre National d Etudes des Telecommunications, Laboratoire de Bagneux, 196 A enue Henri Rw era ...
Journal of Applied Physics, 1981
High-quality homoepitaxial layers of ZnSe have been obtained by the metalorganic method. Optical ... more High-quality homoepitaxial layers of ZnSe have been obtained by the metalorganic method. Optical measurements demonstrate the good purity of these samples. Resonant electronic Raman-scattering experiments have allowed the identification of some residual donors and shown that most of them originate in the substrate. A shallow donor, with an ionization energy of about 30.4 meV, not yet mentioned in the literature, has been observed and is believed to be iodine. Excitation Spectroscopy and Selective Pair Luminescence techniques have shown the existence of a new shallow acceptor associated to a donor-acceptor pair transitions band peaking at 2.75 eV, the ionization energy of which would be about 56 meV. The resonant electronic Raman-scattering technique, used here for the first time to investigate donors, appears much more sensitive than classical luminescence to characterize the semiconductor materials.
Applied Physics Letters, 1983
We have measured the time-resolved decay of photoexcited carriers in InGaAsP subsequent to mode-l... more We have measured the time-resolved decay of photoexcited carriers in InGaAsP subsequent to mode-locked laser pulse excitation at 1.06 μ. Carrier decay rates were evaluated from bleaching recovery and luminescence decay measurements as a function of injected carrier density over a two-decade range (1017–1019 cm−3). At low and moderate density the decay rate follows the variation with excitation expected for radiative decay. At high carrier density (above 2×1018 cm−3), the decay rate increases more rapidly with carrier density, indicating the onset of nonradiative recombination which can be accounted for by Auger recombination with an Auger coefficient of A=2.3±1×10−29 cm6 s−1. This compares to the calculated Auger coefficient range of 0.7–1.4×10−28 cm6 s−1. We discuss the influence of our measured decay rates on the threshold temperature dependence of InGaAsP-1.3 μ lasers by calculating expected T0 values, using a range of representative values for threshold carrier density and tempe...
Applied Physics Letters, 1990
Microfabrication of reactive ion etched InGaAsP/InP and GaAs/GaAlAs quantum wire structures with ... more Microfabrication of reactive ion etched InGaAsP/InP and GaAs/GaAlAs quantum wire structures with dimensions down to 30 nm has been achieved. From time-resolved photoluminescence, the importance of surface recombination effects is outlined in both systems. It is shown that the use of epitaxial overgrowth leads to a significant increase of the carrier lifetime in GaAs/GaAlAs wires, so that emission of very narrow wires (width<40 nm) can be detected. The possible assignment of the observed shifts of the cw photoluminescence peak energies to additional lateral confinement effects is discussed.
Time resolved luminescence measurements under resonant excitation were perfonned at 10 K on the f... more Time resolved luminescence measurements under resonant excitation were perfonned at 10 K on the free exciton in very high quality GaAs-AlAs quantum wells. At resonance, the luminescence intensity is increased by two orders of magnitude, and the decay is short. The radiative lifetime of the excitons in the radiant states is about 18 ps in agreement with the theory of Hanamura and Andréani. The lifetime of the thermalized excitons is about 80 ps at low excitation and it increases with the excitation density.
Physical Review B, 2000
By exciting resonantly a microcavity with a pulsed laser beam, we have observed the in-plane prop... more By exciting resonantly a microcavity with a pulsed laser beam, we have observed the in-plane propagation of excitonic cavity polaritons over distances much greater than the wavelength. The initial in-plane wave vector is conserved during the propagation, showing that it is a good quantum number for cavity polaritons. The polariton group velocities were measured as a function of both the in-plane wave vector and detuning. Propagation is faster for negative detunings where the polaritons have a light effective mass. The observations are in good agreement with a simple two-oscillator model.
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Papers by Bernard Sermage