Benoît Marie Joseph Deveaud

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Using femtosecond pump-probe spectroscopy, we identify excitation-induced dephasing as a major mechanism responsible for the breakdown of the strong coupling between excitons and photons in a semiconductor microcavity. The effects of dephasing are observed ...

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 ...

The quest for identification and understanding of fractional vorticity is a major subject of research in the quantum fluids domain, ranging from superconductors, superfluid Helium-3 to cold atoms. In a two-dimensional Bose degenerate gas with a spin degree ...

We optically excited the eigenmodes of an elliptic resonator in a semiconductor microcavity. Using a pulsed excitation, we created a superposition of eigenmodes, and imaged the temporal evolution of the coherent emission pattern. A semiconductor quantum we ...

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 study the ultrafast properties of secondary radiation of semiconductor quantum wells under resonant excitation. We show that the exciton density dependence allows one to identify the origin of secondary radiation. At high exciton densities, the emission is due to incoherent luminescence with a rise time determined by exciton-exciton scattering. For low densities, when the distance between excitons is much larger than their diameter, the temporal shape is independent of density and rises quadratically, in

We develop an analytical approximate method for determining the Bohr radii of Wannier-Mott excitons in thin quantum wells under the influence of magnetic field perpendicular to the quantum well plane. Our hybrid variational-perturbative method allows us to ...

Cavity polaritons, the elementary optical excitations of semiconductor microcavities, may be understood as a superposition of excitons and cavity photons(1). Owing to their composite nature, these bosonic particles have a distinct optical response, at the same time very fast and highly nonlinear. Very efficient light amplification due to polariton-polariton parametric scattering has recently been reported in semiconductor microcavities at liquid-helium temperatures(2-11). Here we demonstrate polariton param

We experimentally investigate the relaxation of spatially confined microcavity polaritons. We measure the time- and energy-resolved photoluminescence under resonant excitation and in the low-density regime. In this way, we have access to the time evolution ...

Time-resolved up-conversion measurements of secondary emission from multiple quantum wells under resonant femtosecond excitation are reported for GaAs multiple quantum wells with qualitatively different interface disorder. The transient resonant Rayleigh scattering presents very peculiar features such as a long-lived signal and a nonmonotonic behaviour, which cannot be explained by a classical model. A microscopic model is proposed, where the quantum mechanical equation for the microscopic polarization is s

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 ...

We have performed spectral interferometry with Rayleigh scattered light coming from a single speckle and emitted after resonant creation of excitons in GaAs quantum wells:: The experiment confirms the coherence of the secondary emission at early times, regardless of sample:parameters. but underlines the stochastic nature of a single speckle. The scattered electric field is calculated, correctly accounting for the center-of-mass quantization in the disordered potential. We find that the amplitudes of the ele

Real- and momentum-space spectrally resolved images of microcavity polariton emission in the regime of condensation are investigated under nonresonant excitation using a laser source with reduced intensity fluctuations on the time scale of the exciton life ...

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 ...

Phase transitions to quantum condensed phases - such as Bose - Einstein condensation (BEC), superfluidity, and superconductivity - have long fascinated scientists, as they bring pure quantum effects to a macroscopic scale. BEC has, for example, famously be ...

The adiabatic approximation is used to describe the electron states of weakly-one-dimensional quantum wires. A clear order is evidenced in the longitudinal optical (LO) phonon mediated transition rates with respect to the quantum numbers of the confined states involved. The average single electron relaxation time from an excited level is shown either to increase or, surprisingly; to decrease as a function of the initial energy. The relaxation of an excited population is dynamically simulated, showing the wi

The electron states of weakly-one-dimensional quantum wires are computed using the adiabatic approximation in the framework of the k . p theory and the envelope-function approximation. The computed transition rates of electrons from one confined state to any other, mediated by the longitudinal optical (LO) phonons, are clearly ordered with respect to the quantum numbers of the states provided by the adiabatic approximation. The average single electron relaxation time from an excited level is shown to either

We have studied the luminescence of narrow quantum wires at photoexcitation densities of up to similar to 3 x 10(6) cm(-1). We show that even at these densities, which are well above the expected Mott density of 8 x 10(5) cm(-1), excitonic recombination dominates over other recombination channels in stark contrast with the behavior of quantum wells and bulk structures at equivalent densities. As we observe no significant shift in the peak energy with density, an upper limit to the band gap renormalization c

Singly quantized vortices have already been observed in many systems, including the superfluid helium, Bose-Einstein condensates of dilute atomic gases, and condensates of exciton-polaritons in the solid state. Two-dimensional superfluids carrying spin are ...

Benoît Marie Joseph Deveaud

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Dephasing effects on coherent exciton-polaritons and the breakdown of the strong coupling regime

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

Dissociation dynamics of singly charged vortices into half-quantum vortex pairs

Coherent oscillations between orbital angular momentum polariton states in an elliptic resonator

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

Resonant femtosecond emission from quantum well excitons: The role of Rayleigh scattering and luminescence

Analytical method for determining quantum well exciton properties in a magnetic field

High-temperature ultrafast polariton parametric amplification in semiconductor microcavities

Enhancement of microcavity polariton relaxation under confinement

Resonant Rayleigh scattering on quantum well excitons: Theory and experiment

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

Interferometric analysis of resonant Rayleigh scattering from two-dimensional excitons

Coexisting nonequilibrium condensates with long-range spatial coherence in semiconductor microcavities

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

Bose-Einstein condensation of exciton polaritons

Electron relaxation by LO phonons in quantum wires

Electron relaxation by LO phonons in quantum wires: An adiabatic approach

Coulomb correlation and band gap renormalization at high carrier densities in quantum wires

Observation of Half Quantum Vortices in an Exciton-Polariton Condensate