THE EFFECT OF DISORDER ON THE EXCITON DYNAMICS IN CATION-SUBSTITUTED ZNXCD1-XS MIXED-CRYSTALS

When studying time-integrated and, especially, picosecond time-resolve d excitonic luminescence of cation-substituted ZnxCd1-xS (0 less than or equal to x less than or equal to 0.6) mixed crystals at T = 1.8 K a number of remarkable differences is revealed in comparison with the t ypical behaviour of disorder-localized excitons known to dominate in t he anion-substituted model system CdSeyS1-y. It is suggested that the ''tail'' states originate to a considerable extent from the inhomogene ously broadened levels of impurity-bound excitons whereas the role of disorder-induced fluctuations of crystal potential, in contrast to CdS eyS1-y, is less decisive. (C) 1998 Elsevier Science B.V. All rights re served.