Anomalous diamagnetic shift of excitons in II-VI quantum dots and in indirect short period superlattices

We report recent experimental results of magneto-optical spectroscopy of semiconductor nanostructures in pulsed high magnetic fields, Owing to high magnetic fields that allow high-resolution measurements, many new features were observed concerning electronic and excitonic states confined in the quantum potential, In the photoluminescence from excitons in CdSe/ZnSe quantum dots, it was found that the diamagnetic shift is towards the lower energy (red shift) for a relatively small dot diameter of about 5 nm, and the luminescence intensity decreases with increasing field for these excitons, For larger quantum dots, the diamagnetic shift is a blue shift as in the normal case, The anomalous behavior of excitons in magnetic fields is similar to the case for excitons in GaP/AlP short period superlattices, where the exciton peak shows a prominent decrease in intensity when the field is applied perpendicular to the layers. Both these effects are explained by a model assuming a shrinkage of wave functions of spatially separated electrons and holes. (C) 2002 Elsevier Science B.V. All rights reserved.