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CPP: Chemische Physik und Polymerphysik

CPP 6: Electronic Structure and Spectroscopy I

CPP 6.4: Talk

Monday, March 27, 2006, 15:15–15:30, ZEU 114

Charge Transfer Processes as the Source of Emission Intermittency of Semiconductor Quantum Dots — •Abey Issac¹, F. Cichos², and C. von Borczyskowski¹ — ¹Optical Spectroscopy and Molecular Physics — ²Photonics and Optical Materials, Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany

The emission intermittency of quantum dots (QDs) is one of the striking phenomena of single quantum objects. Its occurrence is unwanted and wanted at the same time since it intermits the observation of the QDs but resembles to be one of the simplest switching events possible in a nano-object.Based on extensive measurements on the emission intermittency of single CdSe quantum dots in different dielectric environments, we show that this intermittency is controlled by the dielectric properties of the local environment [1]. Both, the duration of the emitting periods as well as of the dark periods respond to the dielectric function of the matrix material. This is a direct sign for a photo-induced charge transfer process as the source of the intermittency. Referring to recent theoretical models [2], we demonstrate that features of a diffusion controlled charge transfer process can be identified in the experimental statistics of single quantum dot intermittency. The combination of experiment and theory allows exploring the involved energy states, energy barriers and dielectric reorganization energies. [1] J.Tang et al. J. Chem.Phys. 123, 054704 (2005) [2] A. Issac et al. Phys. Rev. B. 71, 161302(R) (2005)