Home  About us  Contact
 

GaAs Quantum Wells (gaa + quantum_well)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Theory of laser cooling of semiconductor quantum wells

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2008
G. Rupper
Abstract We present a microscopic many-body theory of laser cooling of semiconductor quantum wells. The cooling mechanism is the upconversion of pump photons through absorption and subsequent luminescence by an electron,hole,exciton mixture maintained at steady state in the quantum well. Assuming this Coulomb plasma to be in quasi-thermal equilibrium, our theory calculates its absorption/luminescence spectra within a diagrammatic (real-time) Green's function approach at the self-consistent T-matrix level. These spectra are used in a cooling threshold analysis for GaAs quantum wells that also takes into account other losses into heat. We compare the present results with previous ones obtained for bulk GaAs. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Coherent spin transport by acoustic fields in GaAs quantum wells

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2006
O. D. D. Couto
Abstract We review processes for long-range spin transport and manipulation in GaAs quantum wells using mobile potentials created by the piezoelectric field of a surface acoustic wave. By reducing spin dephasing mechanisms associated with the spin orbit-coupling, these potentials can coherently transport spins over distances on the order of 100 µm. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Coherence length and time of excitons in ZnSe quantum wells

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2004
B. Dal Don
Abstract We investigate the in-plane transport of excitons in quantum wells by nano-photoluminescence. The experimental method is based on a confocal microscope with an enhanced resolution given by the introduction of a solid immersion lens. In combination with pulsed laser excitation and streak-camera detection, we have access to transport phenomena on a timescale faster than the time of scattering with acoustic phonons and a length scale of the light wavelength. We use ZnSe-based quantum wells as a model system since hot excitons with well defined excess energy can be formed assisted by the emission of optical phonons. This results e.g. in a periodic quenching of the excitonic transport length as function of excitation excess energy which, in comparison, is not found in GaAs quantum wells. Monte Carlo simulations of the nonlinear expansion of the luminescence spot observed as a function of time reveal the difference between the spatial profiles of the luminescence and the exciton density. The latter shows an oscillatory behaviour in time due to the dominant backscattering, when the first acoustic phonon is emitted. From this oscillation we can determine simultaneously the coherence time and length of the excitonic transport in ZnSe quantum wells. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]