Berlin 2015 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 44: Quantum dots: Preparation and characterization

HL 44.12: Vortrag

Mittwoch, 18. März 2015, 12:30–12:45, EW 203

Strain in colloidal CdSe/CdS core/shell nanocrystals — •Narine Ghazarian¹, Amelie Biermann¹, Tangi Aubert², Marco Cirillo², Andrei Schliwa¹, Zeger Hens², Janina Maultzsch¹, Axel Hoffmann¹, and Christian Thomsen¹ — ¹Institut für Festkörperphysik, Technische Universität Berlin, Germany — ²Physics and Chemistry of Nanostructures, Ghent University, Belgium

In the last decade colloidal quantum dots have attracted particular attention due to their unique size-tunable emission wavelength from UV to IR, their high photoluminescence quantum yield and long lifetime, thus they offer uses in the field of optoelectronics and biotechnology. Surface defects cause non-radiative recombination of charge carriers. One solution to this can be the coating with a shell material. However, overcoating the core with a shell leads to strain inside the core/shell nanocrystals (NC) caused by the lattice mismatch between the different materials. Since strain has a significant bearing on optical properties, it is important to know what impact parameters such as temperature, reaction duration, crystal size and shell thickness have. In order to be able to assess the influences of these parameters on strain, we investigate different series in CdSe/CdS core/shell NCs with wurtzite and zinc blende structure by using Raman spectroscopy. We consistently find that core and shell show compressive and tensile strain, respectively. Increasing the shell thickness results an increased compressive strain in the core and relaxation of the tensile strain in the shell.