Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 7: II-VI semiconductors

HL 7.5: Talk

Monday, February 25, 2008, 12:30–12:45, EW 201

Radiation induced coupling of semimagnetic quantum dots — •Thomas Schmidt¹, Fabian Spielberger¹, Lukas Worschech¹, Alfred Forchel¹, Taras Slobodskyy², and Laurens Molenkamp² — ¹Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — ²Experimentelle Physik III, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

In 1954 R. H. Dicke pointed out that the particles of a spontaneously radiating gas can not be regarded as independent as long as they interact with a common radiation field [1]. Here we present optical studies performed with CdMnSe quantum dots (QDs), which indicates that due to Mn not only the nonradiative decay because of the internal Mn transition is altered but also the radiative decay undergoes a change associated with a Mn enhanced coupling of quantum dots by their radiation field [2]. The range of such a radiant coupling is in the order of the emission wavelength. By analyzing the photoluminescence intensity and the decay rate of quantum dots for differently sized mesas, it was observed that the quantum yield is larger for quantum dots embedded in large mesas with many quantum dots. Removing QDs slows down the PL decay associated with a cooperative radiation of the QDs. Interestingly, by comparison of different excitation conditions it was found that incorporation of Mn into the samples enhances the far-field coupling.

[1] R. H. Dicke, Physical Review 93, 99 (1954)

[2] M. Scheibner, et al., Nature Physics 3, 106 (2007).