Dynamics of exciton transfer between the bound and the continuum states in GaAs-AlxGa1-xAs multiple quantum wells.

Nonparabolic band effects in GaAs/AlxGa1−xAs quantum dots and ultrathin quantum wells

We have investigated the optical properties of unstrained GaAs/AlxGa1−xAs quantum dot/well systems with the aim of studying the influence of confinement on the effective exciton mass, as determined from the photoluminescence line shift in high magnetic fields 50 T . The effective exciton mass is found to be more than twice the value for bulk GaAs. We attribute this to an enhanced nonparabolicit...

Free-carrier effect on exciton dynamics in GaAs/AlxGa1-xAs quantum wells.

Negatively and positively charged excitons in GaAs/AlxGa1-xAs quantum wells.

We report the observation of the positively charged exciton and of the triplet state of the negatively charged exciton in modulation doped GaAs quantum wells. Applying a gate voltage at high magnetic fields we find that the photoluminescence line of the two-dimensional electron gas smoothly transforms into a negatively charged exciton and not into a neutral exciton. The Zeeman splitting of this...

Electronic structures of GaAs/AlxGa1-xAs quantum double rings

In the framework of effective mass envelope function theory, the electronic structures of GaAs/AlxGa1-xAs quantum double rings (QDRs) are studied. Our model can be used to calculate the electronic structures of quantum wells, wires, dots, and the single ring. In calculations, the effects due to the different effective masses of electrons and holes in GaAs and AlxGa1-xAs and the valence band mix...

Effect of charge-carrier screening on the exciton binding energy in GaAs/AlxGa1-xAs quantum wells.

Exciton binding energies of heavyand light-hole excitons affected by charge-carrier screening in GaAs-Al„Ga& As quantum wells are calculated by the variational-perturbation method. The exciton binding energies are found to decrease rapidly when the screening length is less than 30az (effective exciton Bohr radius). This screening length corresponds to a carrier density of 7.0X 10"/cm at T=10 K....