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

Abstract

A negatively charged quasi-two dimensional exciton ($X^{-}$) is solved exactly 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 (PL) signature. The theory provides a quantitative explanation of recent experimental results obtained for a GaAs quantum well. Effects are found which cannot be described within a lowest Landau level approximation. PACS: 78.20.Ls 78.66.-w 73.20.Dx

Minor revisions, mainly removal of the term trion in favour of the term charged-exciton to comply with Physical Review B. To be published as a Rapid Communication in Physical Review B