Defect-related recombination processes in low-dimensional structures of ZnCdSe/ZnSe, CdTe/CdMnTe and GaAs/AlGaAs

The two-line structure of the photoluminescence (PL) emission from quantum wells (QWs) of nominally undoped II-VI and III-V semiconductors is often related to a simultaneous observation of free and bound (typically neutral donor bound) excitons. In this work we discuss defect-related recombination processes in doped and undoped quantum well structures of II-VI and m-V semiconductors. We show that trapping of free excitons by donor impurities is relatively inefficient in typical quantum well structures, which show at low temperature pi, emission of either localized (by potential fluctuations) or quasi-localized excitons. Bound excitons are preferentially formed in such structures under excitation conditions which generates free electrons and holes.