Jean-Daniel Ganière

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GaAs/AlxGa1-xAs multiple-quantum-well (MQW) structures with identical well thicknesses but with different Al contents x in the barrier (x almost-equal-to 0.1, 0.2, 0.45, and 1) were grown by molecular-beam epitaxy to study the impurity-induced disordering mechanism. The disordering of the structures is observed directly by transmission electron microscopy on cleaved wedges of the sample, by the secondary electron imaging mode of scanning electron microscopy, and by secondary-ion-mass spectroscopy after Zn d

We present a combined low-temperature time-resolved cathodoluminescence and photoluminescence study of exciton recombination mechanisms in a 3.8 nm thick a-plane (Al,Ga)N/GaN quantum well (QW). We observe the luminescence from QW excitons and from excitons ...

Both weakly and strongly confined excitons are studied by time-resolved photoluminescence in a nonpolar nitride-based heterostructure grown by molecular beam epitaxy on the a-facet of a bulk GaN crystal, with an ultralow dislocation density of 2 × 105 cm-2 ...

Time-resolved fluorescence spectra for C60 mols. embedded in Ne and Ar matrixes and C70 in Ne matrixes were recorded using a synchroscan streak camera. In the case of C60, the decay times of the S1 state are identical for all fluorescence bands confirming that it is a state of mixed T1g, T2g, and Gg characters. Its lifetime is detd. by the intersystem crossing rate to the triplet manifold which increases in going from Ar to Ne matrixes. This is attributed to a change of the dominant symmetry character of S1

We demonstrate three-dimensional spatial confinement of exciton-polaritons in a semiconductor microcavity. Polaritons are confined within a micron-sized region of slightly larger cavity thickness, called mesa, through lateral trapping of their photon compo ...

In this study, we present the optical properties of nonpolar GaN/(Al,Ga)N single quantum wells (QWs) grown on either a- or m-plane GaN templates for Al contents set below 15%. In order to reduce the density of extended defects, the templates have been proc ...

Optimizing the electronic structures and carrier dynamics in semiconductors at atomic scale is an essential issue for innovative device applications. Besides the traditional chemical doping and the use of homo/heterostructures, elastic strain has been prop ...

A review of experimental results obtained by different techniques is presented on the problem of zinc diffusion. Zinc diffusion was carried out on Si-doped GaAs (n almost-equal-to 10(18) cm-3) and on multiple quantum well (MQW) structures. The samples were investigated by secondary-ion mass spectroscopy (SIMS), different imaging modes of scanning electron microscopy such as secondary electrons, cathodoluminescence (CL) and electron beam-induced current (EBIC), transmission electron microscopy on a wedge-sha

The effects of background n- and p-type doping on Zn diffusion in GaAs/AlGaAs multilayered structures are investigated by secondary-ion-mass spectrometry and photoluminescence measurements. Zn diffusions are performed at 575 degrees C into Si-doped, Be-doped, and Si/Be-codoped identical GaAs/Al0.2Ga0.8As multiple-quantum-well structures. The results obtained by secondary-ion-mass spectrometry show that the Zn diffusion induces an enhancement of Be out-diffusion and the disordering of all structures. The eff

We investigate, via time-resolved photoluminescence, the temperature-dependence of charge carrier recombination mechanisms in nonpolar (Al,Ga)N/GaN single quantum wells (QWs) grown via molecular beam epitaxy on the a-facet of bulk GaN crystals. We study the influence of both QW width and barrier Al content on the dynamics of excitons in the 10-320 K range. We first show that the effective lifetime of QW excitons s increases with temperature, which is evidence that nonradiative mechanisms do not play any sig

The exciton transport is studied in high quality ZnO microwires using time resolved cathodoluminescence. Owing to the available picosecond temporal and nanometer spatial resolution, a direct estimation of the exciton average speed has been measured. When r ...

The evolution of GaN luminescence under electron beam injection has been studied by means of in situ cathodoluminescence experiments on various epitaxial lateral overgrown samples. It is shown that the ultraviolet (UV) peak of undoped materials experiences a decrease of its intensity as well as a noticeable redshift, while the other extrinsic peaks only experience an intensity decrease. However, in Mg doped materials the UV peak intensity decrease is followed by an increase of its intensity which can even r

We study the effects of the vicinity between a shallow donor nucleus and an I1-type basal stacking fault (BSF) in GaN. We propose a numerical calculation, in the “effective potential” formalism, of energies and envelope functions of electrons submitted to ...

In a recent paper, we measured the hole diffusion length in a single quantum well (SQW) by a novel method using SEM-cathodoluminescence, assuming that the carriers diffuse only in the SQW. This assumption needs to be checked. Therefore, we present here a model for the carrier transport in the SQW and in the bulk barrier to deduce the lateral hole distribution in both layers. The main lateral transport is shown to be carried by the holes in the QW (2D diffusion) due to their confinement in the well.

Elastic strain engineering is an important way to reversibly tune the properties of micro/nanoscale semiconductors for promising applications in the emerging advanced nanotechnologies, such as the strain enhanced high-mobility transistors, nanogenerators, ...

The mechanism of silicon diffusion in GaAs, Al0.3Ga0.7As, and the silicon diffusion-induced layer disordering of multiquantum wells have been studied by photoluminescence, secondary-ion-mass spectroscopy, and transmission electron microscopy across a corner of a wedge-shaped sample. The diffusion source was a grown in highly Si-doped layer. The main photoluminescence properties of point defects in GaAs and Al0.3Ga0.7As are reviewed to interpret the experimental data. The depth profile of the photoluminescen

A detailed study of excitons in unstrained GaN nanocolumns grown by plasma assisted molecular beam epitaxy on silicon substrates is presented. The time-integrated and time-resolved photoluminescence spectra do not depend significantly on the (111) or (001) ...

The design of cost-effective standards for the quality of nano-objects is currently a key issue toward their massive use for optoelectronic applications. The observation by photoluminescence of narrow excitonic and biexcitonic emission lines in semiconduct ...

This article presents the dynamics of excitons in a-plane (Al,Ga)N/GaN single quantum wells of various thicknesses grown on bulk GaN substrates. For all quantum well samples, recombination is observed to be predominantly radiative in the low-temperature ra ...

After Zn diffusion into Si-doped GaAs (n almost-equal-to 1.5 X 10(18) cm-3), the Zn-diffused samples are annealed under different conditions: (i) in vacuum, (ii) in arsenic vapor, and (iii) with a Si3N4 mask capping the sample surface. The Zn concentration profiles obtained by secondary-ion-mass spectroscopy and the photoluminescence (PL) spectra taken at different depths below the sample surface are studied in detail. After annealing in vacuum, the steep (p+-n) Zn diffusion front advances into the bulk. We

Jean-Daniel Ganière

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Self-Interstitial Mechanism for Zn Diffusion-Induced Disordering of Gaas/Alxga1-Xas (X=0.1-1) Multiple-Quantum-Well Structures

Exciton recombination dynamics in a-plane (Al,Ga)N/GaN quantum wells probed by picosecond photo and cathodoluminescence

Intrinsic dynamics of weakly and strongly confined excitons in nonpolar nitride-based heterostructures

Picosecond studies of the intramolecular relaxation processes in isolated C60 and C70 molecules

Engineering the spatial confinement of exciton polaritons in semiconductors

One-dimensional exciton luminescence induced by extended defects in nonpolar GaN/(Al,Ga)N quantum wells

Exciton Drift in Semiconductors under Uniform Strain Gradients: Application to Bent ZnO Microwires

Zinc Diffusion in Gaas and Zinc-Induced Disordering of Gaas Algaas Multiple Quantum-Wells - a Multitechnique Study

Effects of background n- and p-type doping on Zn diffusion in GaAs AlGaAs multiple-quantum-well structures

Thermal carrier emission and nonradiative recombinations in nonpolar (Al,Ga)N/GaN quantum wells grown on bulk GaN

Exciton hopping probed by picosecond time-resolved cathodoluminescence

Cathodoluminescence of epitaxial GaN laterally overgrown on (0001) sapphire substrate. Time evolution with low energy electron beam

Electron localization by a donor in the vicinity of a basal stacking fault in GaN

Measurements of the Diffusion Length in GaAs/AlGaAs Quantum-Well (Qw) Structures by Cathodoluminescence - Comparison of the Bulk and Qw Diffusion Channels

Temperature Dependent Exciton Funnel Dynamics in Uniform Strain Gradient Field Observed by Time-Resolved Photoluminescence

Role of Point-Defects in the Silicon Diffusion in Gaas and Al0.3ga0.7as and in the Related Superlattice Disordering

Time-resolved spectroscopy on GaN nanocolumns grown by plasma assisted molecular beam epitaxy on Si substrates

Biexciton emission and crystalline quality of ZnO nano-objects

Temperature-Dependence of Exciton Radiative Recombination in (Al,Ga)N/GaN Quantum Wells Grown on a-Plane GaN Substrates

Effects of Post-Diffusion Annealing on Zn-Diffused Gaas-Si