Optical observation of quantum-dot formation in sub-critical CdSe layers grown on ZnSe

The evolution of CdSe quantum dot (QD) formation on ZnSe was investigated o n a series of samples grown by MBE, with nominal CdSe coverages ranging fro m 1.1 to 2.6 monolayers (ML). Micro-PL data suggest strongly confined zero- dimensional excitons even for coverages as low as 1.1 ML. PL and micro-PL d ata show emission from the QDs as well as from an accompanying 2 D layer; t he temperature dependence of these emissions is notably different. Strong r ed-shifts of both emissions as the CdSe coverage increases are observed. (C ) 2000 Elsevier Science B.V. All rights reserved.