Jean-Daniel Ganière

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To study the effect of damage induced during the Zn diffusion on the properties of the material, p-n junctions, obtained by zinc diffusion, are investigated by electron beam induced current (EBIC) at different temperatures. At helium temperature, the EBIC decay on the p-side is flattened and non exponential. This effect is attributed to the defects induced by the Zn-diffusion that act as non-radiative centers. The room temperature EBIC signal has a symmetric exponential decay on both sides of the junction.

The properties of ZnSe epilayers fabricated by molecular beam epitaxy on lattice-matched InxGa1-xAs buffers grown on GaAs(001) substrates have been investigated by means of photoluminescence spectroscopy and transmission electron microscopy. For suitable values of x and ternary-layer thickness, the partial character of the strain relaxation within the III-V layer can be compensated for, minimizing the residual strain in the ZnSe overlayer. Large reductions in the dislocation density and Y-line emission as c

The Zn/Se flux ratio employed during the early stages of molecular beam epitaxy of pseudomorphic ZnSe/GaAs(001) as well as lattice-matched ZnSe/In0.04Ga0.96As(001) heterostructures controls the density of the native stacking faults, which have been associated with the early degradation of blue-green lasers. In particular, the density of Shockley stacking fault pairs decreases by three to four orders of magnitude and that of Frank stacking faults by one order of magnitude in going from Zn-rich to Se-rich int

We present the results of a study of the dynamics of trions and excitons in a CdTe modulationdoped quantum well as a function of temperature in the low-density regime. Using three-pulse four-wave mixing technique, we show that, at low temperature, these quasi-particles are inhomo-geneously broadened and localized due to disorder effects. At higher temperatures, trions and excitons are mobile and their homogeneous broadening is largely increased as a result of acoustic phonon scattering. Consistently, time-r

We report a cathodoluminescence (CL) study at helium temperature of oval defects on quantum well (QW) structures grown by molecular beam epitaxy (MBE). We collected the luminescence emitted both from the facet shaped defect and from the defect free growth region. By comparing the experimental CL peak position with the numerically estimated values, we determined the Al concentration and the thicknesses of the layers in the defect area.

Photoluminescence magnetospectroscopy is employed to examine the low-temperature magnetic phase that is induced by the carrier-mediated ferromagnetic exchange interaction in modulation-doped Cd1-xMnxTe quantum well. Unusual properties of the domain structure are linked to tendency towards spin-density wave formation in this low-dimensional magnetic system. (C) 2000 Elsevier Science B.V. All rights reserved.

Microgun-pumped blue lasers with lasing thresholds in the 4-20 kW/cm(2) range for temperatures between 83 and 225 K were fabricated by molecular beam epitaxy. The devices exploit graded index, separate confinement Zn1-xCdxSe/ZnSe heterostructures and use an array of low-voltage field-emission microtips for electron beam pumping. Degradation occurs through the formation of characteristic (100) dark-line defects, as in diode lasers. The device lifetime exceeded several hours at 83 K for a laser operating at 4

The conduction band offset in ZnSe/GaAs n-p heterodiodes was determined from measurements of the low-temperature tunneling current of photoinjected carriers, We found widely different discontinuities for heterojunctions fabricated with different Zn/Se flux ratios, with conduction band offsets as high as 0.75 eV for Se-rich interfaces, and as low as 0.26 eV for Zn-rich interfaces. (C) 1996 American Institute of Physics.

A high-reflectance GaInP/GaAs distributed Bragg reflector (DBR) was grown by chemical beam epitaxy (CBE). The mirror consists of 40 pairs of alternating layers and was designed for a centre wavelength of 980 nm, resulting in a total thickness of 5.8 mum. Highly stable growth conditions led to a maximum reflectance of 0.99 and to a variation in the centre wavelength of only 5 nm over the 2'' (50.8 mm) wafer. Transmission electron microscopy and X-ray diffraction measurements confirmed the vertical uniformity

We have determined the origin of the spatial luminescence fluctuations observed between the dark line defects present in tensile strained GaxIn1-xP/In1-xP/n(+)-InP heterostructures (Part I [F. Cleton et al. J. Appl. Phys. 80, 827 (1996)]). For that purpose, we have undertaken semi-quantitative and spectroscopic cathodoluminescence (CL) measurements on various specimens in areas exhibiting CL contrasts which could be as large as 80%. The analysis of the variation of the CL polychromatic signal with electron

The emission properties of self-assembled InAs quantum dots (QDs) and lattice-matched GaInNAs quantum wells (QWs) emitting around 1.3 mum were investigated by temperature-dependent and time-resolved photoluminescence (PL). The QDs have much higher PL efficiency at low excitation, but saturate faster as the excitation is increased, due to the lower density of states. Lifetime measurements show that nonradiative recombination plays a more important role in the GaInNAs QW than in QDs. (C) 2002 American Institu

We investigate the spin relaxation of negatively charged excitons in modulation-doped CdTe quantum wells by time-resolved photoluminescence. The charged exciton spin flip process is found to be very sensitive to the excitation energy but not to a change of electron concentration. We exclude the Bir-Aronov-Pikus mechanism, which is based on the exchange interaction, as responsible for the X- spin flip.

We report transmission electron microscopy studies of native extended defects in pseudomorphic ZnSe/GaAs (001) and lattice-matched ZnSe-In0.04Ga0.96As (001) heterostructures. The dominant defects present in the layers were identified as Shockley stacking fault pairs lying on (111) and fault planes and single Frank stacking faults lying on or fault planes by comparing experimental images with the predictions obtained with the g.b = 0 rule as well as wi

We report on studies of extended defects in electron-beam-pumped Zn1-xCdxSe/ZnSe blue and blue-green laser structures. To establish a direct correlation between the local luminescence properties and the presence of structural defects, the same thin foil samples were sequentially examined by transmission electron microscopy (TEM) and cathodoluminescence (CL) microscopy. The majority of the non-radiative defects were found to have one or more threading dislocations in their vicinity. Stacking faults, as a rul

Lattice-matched ZnSe/InxGa1-xAs heterostructures were fabricated by molecular beam epitaxy on GaAs(001)2x4 surfaces. We find that the partial character of the strain relaxation within the ternary layer can be compensated by a suitable excess in the In concentration to match the free-surface lattice parameter to ZnSe. The surface of the II-VI epilayer, however, exhibits a cross-hatched pattern of surface corrugations oriented along orthogonal [110] directions. This complex surface morphology reflects the for

We have performed low-density (< 10(5) cm(-1)) time-resolved photoluminescence experiments that probe the relaxation of photo-excited carriers in a quantum wire. Our results show that carrier-carrier collisions are dominant at very short times both for intra- and for inter-subband scattering as only expected if non-Markovian effects are taken into account. (C) 1999 Elsevier Science B.V. All rights reserved.

The intramol. energy relaxation processes of UV-excited C60 mols. embedded in Ar crystals were studied by picosecond fluorescence studies and femtosecond pump-probe absorption spectroscopy. The various internal energy relaxation steps are clearly identified. The importance of intramol. energy relaxation processes in solid C60 films is underlined. [on SciFinder (R)]

Excitons and trions in a CdTe modulation-doped quantum well are investigated by picosecond three-pulse four-wave mixing experiments as a function of temperature in the low-density regime. We show that trions are mobile for high enough temperatures. The diffusivity of trions and excitons increases with temperature but, like their mobilities, is limited by acoustic-phonon scattering. Consistently, studying the decay of the interband coherence reveals an increase of the homogeneous broadening as the temperatur

Two tensile-strained GaxIn1-xP / InP (001) heterostructures (with x = 6.5% and x = 11.2%) have been studied by TEM and cathodoluminescence. In both structures stacking faults and twins, located in the epilayer, have been found preferably along the [(1) over bar 10] direction whereas perfect misfit dislocations have been observed at the interface in the [110] and [(1) over bar 10] directions. The two types of structures differ about the nature of the misfit dislocations and about the thickness of the twins a

We explored degradation in electron-beam-pumped Zn1-xCdxSe/ZnSe laser structures by combining cathodoluminescence (CL) measurements in a scanning electron microscope with transmission electron microscopy. The rate of degradation, measured as the decrease of the emitted CL intensity under electron bombardment, depends critically on the threading dislocation density and on the strain in the quantum well. Degradation occurs via the formation of dark spot defects, which are related to bombardment-induced networ

Jean-Daniel Ganière

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Low‐Temperature EBIC Study of Zn‐Diffused GaAs p‐n Junctions

ZnSe growth on lattice-matched InxGa1-xAs substrates

Interface composition and stacking fault density in II-VI/III-V heterostructures

Trions and excitons in CdTe quantum wells: Lifetimes, coherence, diffusion and localization

Cathodoluminescence Study of Oval Defects on Qw Structures

Ordered magnetic phase in Cd1-xMnxTe/Cd1-y-zMgyZnzTe : N heterostructures: magnetooptical studies

Degradation of microgun-pumped blue lasers

Tuning of ZnSe-GaAs band discontinuities in heterojunction diodes

High-reflectance GaInP/GaAs distributed Bragg reflector

Transmission electron microscopy and cathodoluminescence of tensile-strained GaxIn1-xP/InP heterostructures .2. On the origin of luminescence heterogeneities in tensile stress relaxed GaxIn1-xP/InP heterostructures

Comparison of radiative properties of InAs quantum dots and GaInNAs quantum wells emitting around 1.3 mu m

Spin relaxation of negatively charged excitons in CdTe quantum wells

Stacking faults in pseudomorphic ZnSe-GaAs and lattice-matched ZnSe-In0.04Ga0.96As layers

Transmission electron microscopy and cathodoluminescence studies of extended defects in electron-beam-pumped Zn1-xCdxSe/ZnSe blue-green lasers

Strain and surface morphology in lattice-matched ZnSe/InxGa1-xAs heterostructures

Intrasubband and intersubband scattering in semiconductor quantum wires

Picosecond and femtosecond studies of the energy redistribution in matrix-isolated C60 molecules

Diffusion, localization, and dephasing of trions and excitons in CdTe quantum wells

Cathodoluminescence and TEM investigations of stress relaxation mechanisms in GaxIn1-xP/InP heterostructures

Combined transmission electron microscopy and cathodoluminescence studies of degradation in electron-beam-pumped Zn1-xCdxSe/ZnSe blue-green lasers