Stability of optically active charged excitons in quasi-two-dimensional systems

A negatively charged quasi-two-dimensional exciton (X-) is studied numerically in the presence of a uniform perpendicular B field. Various quasi-two-dimensional geometries are studied. The charge distribution of the X- parallel to the B field is found to be crucial in determining the stability of the optically active X- and hence its photoluminescence signature. The theory provides a quantitative explanation of recent experimental results obtained for a GaAs quantum well. Effects are found that cannot be described within a lowest-landau-level approximation.