GaAs-AlAs Quantum Wells Research Articles

Comment on "Dynamical aspects of luminescence from GaAs-AlAs single quantum wells under hydrostatic pressure"

It is shown that the slow-time domain in the luminescence of GaAs-AlAs quantum wells under pressure reported by Masumoto et al. [Phys. Rev. B 40, 11772 (1989)] peaks at a critical pressure that is independent of structural parameters. As expected from theory, the position of the peak below the crossover is not linked to valley mixing.

Resonant Raman scattering in GaAsAlAs quantum wells under high magnetic fields

Double Resonant Raman scattering has been observed in GaAs-AlAs Multiquantum Wells under high magnetic fields, when both the incident laser energy and the scattered frequency match simultaneously different magneto-exciton transitions. The results can be explained in terms of exciton-phonon interaction rather than electro- (or hole-) phonon coupling.

Nonlinear Optical Study of Semiconductor Microstructures, CuCl Quantum Dots, and GaAs Quantum Wells

AbstractNonlinear optical properties of zcro‐dimensional and two‐dimensional semiconductor microstructures, CuCl quantum dots and GaAs quantum wells, are studied with special attention to the bleaching and the blue shift of excitons. In CuCl quantum dots, prominent absorption bleaching of excitons is observed together with a blue shift. The optical nonlinearity is found to increase with an increase of the size of the microcrystals. The blue shift of Z3 exciton absorption increases linearly and becomes saturated with the increase of the excitation density, suggesting the possibility of quantized blue shift. In GaAsAlAs quantum wells, two‐step rise in absorption saturation of the lowest exciton is observed in a few picosecond time domain at 4.2 K under the high‐density band‐to‐band excitation. The former rise takes place simultaneously with the dynamical red shift of the electron‐hole plasma luminescence. The latter rise is accompanied with the blue shift of the exciton. The origin of two‐step rise and blue shift is discussed.

Nonlinear Luminescence Spectroscopy of Excitons in GaAs-AlAs Quantum Wells

We present the detailed experimental results of the time-resolved nonlinear luminescence of excitons in undoped GaAs-AlAs quantum wells. The observed nonlinearity results from the saturation in luminescence originated from the phase space filling and exchange effects of carriers. In some temporal profiles of nonlinear luminescence, anomalous anti-correlation profile has been observed. The origin of anti-correlation is ascribed to be the finite rise time of the exciton population at the luminescent tail state in the exciton band.

Surface migration study of atoms and formation of truly-smooth top and bottom heterointerfaces in GaAsAlAs quantum wells by temperature-switched technique in molecular beam epitaxy

We have studied the temperature dependence of migration of atoms on growth-interrupted and uninterrupted GaAs and AlAs growth front in molecular beam epitaxy. The optimum growth condition for achieving truly-smooth surface on an atomic scale is found to be quite different between GaAs and AlAs. On this basis, we have developed a novel temperature-switched technique by which both top (AlAs-on-GaAs) and bottom (GaAs-on-AlAs) interfaces in GaAsAlAs quantum wells can be prepared truly-smooth.

Photoluminescence and absorption linewidth of extremely flat GaAs-AlAs quantum wells prepared by molecular beam Epitaxy including interrupted deposition for atomic layer smoothing

GaAs-AlAs quantum well (QW) structures with extremely flat interfaces are prepared by our new growth procedure and their photoluminescence (PL) and absorption linewidths are studied at various temperatures. The PL linewidths of our QWs measured at 77 and 4.2 K are found to be the narrowest that have ever been published, and indicate the effective interface roughness to be less than 0.19 atomic layer. Excellent correlation was found to exist between the PL and absorption lineshapes, suggesting the validity of estimating interface roughness from the PL linewidths.

Photoluminescence and absorption linewidth of extremely flat GaAs-AlAs quantum wells prepared by molecular beam epitaxy including interrupted deposition for atomic layer smoothing

Photoluminescence and absorption linewidth of extremely flat GaAs-AlAs quantum wells prepared by molecular beam epitaxy including interrupted deposition for atomic layer smoothing

Two-dimensional shrinkage of the exciton wavefunction in quantum wells probed by optical absorption

The oscillator strength of the lowest 1s excitons in GaAsAlAs quantum wells is studied as a function of well layer thickness L z by means of optical absorption. It is enhanced more than the 1 L z dependence with the decrease of L z . The results present the first full experimental observation of two-dimensional shrinkage of the exciton wavefunction in quantum wells.

Direct experimental observation of two-dimensional shrinkage of the exciton wave function in quantum wells.

We have studied the oscillator strength of the lowest 1s heavy excitons in GaAs-AlAs quantum wells as a function of well-layer thickness by means of optical absorption. The oscillator strength of the lowest 1s heavy excitons is largely enhanced with the decrease of well-layer thickness. The result is the first full experimental observation of two-dimensional shrinkage of the exciton wave function in quantum wells.

Inelastic electron scattering by collective charge-density excitations at the surface of a semiconductor superlattice.

We have studied the oscillator strength of the lowest 1s heavy excitons in GaAs-AlAs quantum wells as a function of well-layer thickness by means of optical absorption. The oscillator strength of the lowest 1s heavy excitons is largely enhanced with the decrease of well-layer thickness. The result is the first full experimental observation of two-dimensional shrinkage of the exciton wave function in quantum wells.