Temperature dependent photoluminescence from CdSe/ZnSe nanostructures grown by migration enhanced epitaxy

Abstract

We report on the photoluminescence (PL) studies of CdSe/ZnSe heterostructures with a nominal thickness of CdSe layer ranging from 2 to 3 monolayers (MLs), which can be regarded as a dense (1011–1012 cm–2) array of nanometer-scaled CdSe-enriched quantum dots (QDs) incorporated into the body of alloyed CdZnSe quantum well (QW). QD PL measurements reveal the formation of negatively charged trions, which contribute to the PL spectra of the samples up to the temperature of 100 K, being primarily generated at the excitation of the extended states in the alloyed QW. Non-regular temperature dependence of the QD PL Stokes shift is explained in terms of the excitonic multi-hopping process in the ensemble of the dots and can be described by the models developed for QWs with substantial interface roughness and compositional disorder. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)