Spatially resolved near-field photoluminescence spectroscopy of II-VI quantum wells: The role of localized excitons

Excitons localized at compositional potential fluctuations are individually resolved by spatially resolved near-field luminescence in ZnCdSe/ZnSe quan tum wells at room temperature. Localization is found to occur on a scale le ngth of about 100 nm, in Cd-rich clusters in which the local Cd content var ies by approximately 1% with respect to the nominal composition, and in ste ps of about 0.3%. A microscopic modeling of the localized exciton states is presented, which describes quite well the observed near-field spectra. (C) 1999 American Institute of Physics. [S0021-8979(99)00524-1].