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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.