MAGNETOLUMINESCENCE STUDY ON THE LOW-DIMENSIONALITY OF EXCITONS CONFINED IN A NARROW GAAS ALGAAS QUANTUM-WELL/

Low-dimensional characteristics of excitons confined in a quantum well (QW) are studied by applying a high magnetic field (B). The diamagnet ic shift is best fit with a linear combination of linear and quadratic terms of B. From the quadratic dependence of B, it is obtained that t he exciton becomes two-dimensional (2-D) like when the QW width decrea ses to 15 monolayers (ML). However, the 2-D confinement becomes weak w hen the width becomes smaller than 10 ML. In large B, the field confin ement becomes significant in the electron-hole recombination, and the population inversion of the photo-generated carriers in the islands of ML fluctuation was observed.