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

Comparative study of the negatively and positively charged excitons in GaAs quantum wells

We compare the photoluminescence spectra of the negatively and positively charged excitons in GaAs quantum wells. We use a structure which enables us to observe both complexes within the same sample. We find that their binding energy and Zeeman splitting are very similar at zero magnetic field, but evolve very differently at high fields. We discuss the implications of these observations on our ...

Optical spectroscopy of neutral and charged excitons in GaAs/AIGaAs quantum wells in high magnetic fields

We implement optical spectroscopy to study charged excitons in modulation-doped GaAs/AIGaAs quantum wells. We report the fLrs~ observation of the positively charged exciton and of the triplet state of the negatively charged exciton. Applyin~g a gate voltage at high magnetic fields, we investigate the transition between metallic and insulating state~ We find that while the photoluminescence fine...

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.

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...