STABILITY OF OPTICALLY-ACTIVE CHARGED EXCITONS IN QUASI-2-DIMENSIONALSYSTEMS

A negatively charged quasi-two-dimensional exciton (X-) is studied num erically in the presence of a uniform perpendicular B field. Various q uasi-two-dimensional geometries are studied. The charge distribution o f the X- parallel to the B field is found to be crucial in determining the stability of the optically active X- and hence its photoluminesce nce signature. The theory provides a quantitative explanation of recen t experimental results obtained for a GaAs quantum well. Effects are f ound that cannot be described within a lowest-landau-level approximati on.