Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 43: Quantum dots and wires: Optical properties II
HL 43.5: Vortrag
Donnerstag, 28. Februar 2008, 15:00–15:15, EW 201
Replica of confined acoustic phonons in the photoluminescence of single CdSe/CdS/ZnS core/shell/shell nanocrystals — •Tobias Kipp1, Gerwin Chilla1, Marija Nikolic2, Andreas Frömsdorf2, Torben Menke1, Andreas Kornowski2, Detlef Heitmann1, Stephan Förster2, and Horst Weller2 — 1Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg — 2Institut für Physikalische Chemie, Universität Hamburg
We investigate the photoluminescence (PL) of single CdSe/CdS/ZnS core/shell/shell NCs whose ligands were exchanged to poly(ethylen oxide) (PEO) before they were embedded in a PEO matrix. We find NCs exhibiting a strong and durable PL even under high excitation power. By averaging PL spectra of a single NC, a set of peaks with distinct distance to the zero-phonon line (ZPL) of the NC can be observed. These peaks are attribute to phonon replicas. Most interestingly, by modeling the NC as an elastic sphere and calculating its vibrational modes, we can identify three peaks close to the ZPL as confined acoustic phonon modes: the breathing mode and its two radial harmonics. Other peaks can be assigned to LA and LO phonons of the CdSe core and LO phonons of both the CdS and ZnS shells.
We acknowledge financial support by the Deutsche Forschungsgemeinschaft via the SFB 508.