Morphology of CdSe/ZnSe quantum dots grown by MBE

Autor: B. Gilles, I. C. Robin, Catherine Bougerol, Régis André, G. Van Tendeloo, B. Van Daele
Přispěvatelé: Laboratoire de Spectrométrie Physique (LSP), Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Electron Microscopy for Material Resaerch (EMAT) (EMAT), University of Antwerp (UA)
Rok vydání: 2006
Předmět:
Zdroj: physica status solidi (c)
physica status solidi (c), Wiley, 2006, 3 (4), pp.938-941. ⟨10.1002/pssc.200564747⟩
ISSN: 1610-1642
1862-6351
1610-1634
DOI: 10.1002/pssc.200564747
Popis: The features of CdSe/ZnSe quantum dots (QDs) grown by molecular beam epitaxy at 280 °C and 240 °C are studied by transmission electron microscopy (TEM), atomic force microscopy (AFM) and photoluminescence (PL). The epitaxial structures consist of a single layer of CdSe islands sandwiched between two 40 nm thick ZnSe layers grown on a [100]-oriented GaAs substrate. UHV-AFM shows that islands are formed as a result of strain relaxation in 3 ML of CdSe pseudomorphically deposited on ZnSe. After encapsulation at 240 °C, there is no change in the QDs' morphology. On the other hand, at higher temperature, interdiffusion and segregation phenomena take place. Flat islands originating from a wetting layer and pointing to the substrate are observed, with a Cd concentration much lower in their center than at the outskirts. Both size and composition are consistent with the ∼2.35 eV PL energy that we measured. Moreover the unexpected QD morphology with Cd-rich outskirts can explain why the PL decay time depends on the samples because the confinement of holes in the QD edges makes the electron-hole overlap very sensitive to QD size. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Databáze: OpenAIRE
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