Structural and chemical characterization of CdSe-ZnS core-shell quantum dots

Publication date: 1 November 2018
Source:Applied Surface Science, Volume 457
Author(s): N. Fernández-Delgado, M. Herrera, A.H. Tavabi, M. Luysberg, R.E. Dunin-Borkowski, P.J. Rodriguez-Cantó, R. Abargues, J.P. Martínez-Pastor, S.I. Molina
The structural and compositional properties of CdSe-ZnS core-shell quantum dots (QDs) with a sub-nm shell thickness are analyzed at the atomic scale using electron microscopy. QDs with both wurtzite and zinc blende crystal structures, as well as intermixing of the two structures and stacking faults, are observed. High-angle annular dark-field scanning transmission electron microscopy suggests the presence of a lower atomic number epitaxial shell of irregular thickness around a CdSe core. The presence of a shell is confirmed using energy dispersive X-ray spectroscopy. Despite the thickness irregularities, the optical properties of the particles, such as photoluminescence and quantum yield, show clear enhancement after growth of the ZnS shell.

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