Showing papers by "Benoit Deveaud published in 1991"
TL;DR: Radiative properties of free excitons in a single GaAs quantum well are studied under resonant excitation and a radiative lifetime of 10.4 ps is deduced in the absence of dephasing mechanisms.
Abstract: Radiative properties of free excitons in a single GaAs quantum well are studied under resonant excitation. Enhanced radiative recombination of the excitons, caused by the breakdown of the translational symmetry of the system, is evidenced by the very short lifetime as well as by the strong intensity of the signal. Dephasing mechanisms, by transferring the excitons to nonradiative states, increase the observed lifetime. We deduce a radiative lifetime of 10\ifmmode\pm\else\textpm\fi{}4 ps in the absence of dephasing mechanisms.
236 citations
TL;DR: In this article, photoexcited carrier trapping in a GaAs/Al/sub x/Ga/sub 1-x/As single quantum well with three different typical confinement layer structures was studied by means of time-resolved luminescence with 600-fs resolution.
Abstract: The authors report experimental and theoretical studies of photoexcited carrier trapping in a GaAs/Al/sub x/Ga/sub 1-x/As single quantum well with three different typical confinement layer structures: a separate-confinement heterostructure (SCH) and a graded SCH (GRIN-SCH), a linearly graded SCH (LGRIN-SCH), and a parabolically-graded SCH (PGRIN-SCH). The capture is studied by means of time-resolved luminescence with 600-fs resolution. Measurements, performed from 20 to 300 K, show an appreciably shorter trapping time in the GRIN-SCH (1 ps at 80 K to 8 ps at 300 K) than in the SCH (between 22 and 14 s in the same temperature range). Experimental results are fitted by a one-dimensional drift-diffusion model, and the mobility of holes is deduced from the calculations. A short but finite capture time at the edge of the well is demonstrated. >
80 citations
TL;DR: Analyse de la dynamique de l'effet tunnel resonant dans un potentiel de puits double asymetrique lorsqu'il est combine a un processus de relaxation, resultant en une variation inattendue du temps d'EFFet tunnel en fonction of the vitesse de relaxation.
Abstract: We analyze the dynamics of resonant tunneling in an asymmetric double-well potential when it is combined with a relaxation process. We show that quantum-interference effects could appear in the relaxation process, resulting in an unexpected dependence of the tunneling time on the relaxation rate. These effects prevail even when the system is prepared in an incoherent initial state. We compare our analysis with recent experimental results and show a very good agreement.
27 citations
TL;DR: In this article, a new InP lattice matched material (GaPSb with 65% Sb) has been grown for the first time by gas source molecular beam epitaxy and studied.
Abstract: Despite its excellent transport properties, the low value of the Schottky barrier height on n‐ type InP (0.43 eV) prevents its use in electronic applications. A new InP lattice‐ matched material (GaPSb with 65% Sb) has been grown for the first time by gas source molecular beam epitaxy and studied. The material gap is 0.9 eV and the gold Schottky diode reaches 0.6 eV on this compound. This is the highest barrier ever reported on InP lattice‐matched materials which do not contain aluminum. Continuous and picosecond luminescence results show that the GaPSb/InP is a type II heterostructure with ΔEc=50 meV at 4 K.
24 citations
TL;DR: In this article, the radiative recombination from a single quantum well placed inside a graded confinement structure was studied by using time-resolved luminescence, and the authors were able to produce a cold (T <50 K), high-density (5×1011
Abstract: We study by time‐resolved luminescence, the radiative recombination from a single quantum well placed inside a graded confinement structure. We are able to produce a cold (T<50 K), high‐density (5×1011
10 citations
TL;DR: In this article, femtosecond pump-probe transmission spectroscopy experiments on GaAs/AlGaAs asymmetric-coupled quantum wells, using a spectrally narrow optical excitation at 740 nm.
Abstract: We report femtosecond pump‐probe transmission spectroscopy experiments on GaAs/AlGaAs asymmetric‐coupled quantum wells, using a spectrally narrow optical excitation at 740 nm. The time‐resolved evolution of the bleaching demonstrates the tunneling of both carriers through the barrier. At high densities a single tunneling time is observed in opposition to the low density regime, where the electron and hole contributions are well separated.
3 citations
TL;DR: In this paper, vertical transport in GaAs/AlGaAs superlattices is probed in structures with graded composition, and the importance of the transfer to the satellite valleys and of the finite capture time in the large well included as a marker are evidenced.
Abstract: Vertical transport in GaAs/AlGaAs superlattices is probed in structures with graded composition. Such structures allow both to impose a quasi electric field to the carriers and to evidence the carrier movement by the temporal changes in the luminescence line shape. The fit of this line shape by a drift‐diffusion model gives the transport properties of electrons. High mobility of the electrons is evidenced for the shortest period superlattices, in agreement with previous optical measurements. The importance of the transfer to the satellite valleys and of the finite capture time in the large well included as a marker are evidenced.
2 citations
TL;DR: The existence of minibands of extended states gives to short-period superlattices optical properties quite different from those of multi-quantum wells as discussed by the authors, where the heavy-hole/light-hole splitting is reduced together with the binding energy of excitons and impurities.
1 citations