Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 12: Symposium Quantum optics in semiconductors I

HL 12.2: Fachvortrag

Dienstag, 28. März 2006, 11:45–12:15, HSZ 01

Size-tunable exchange interaction in InAs/GaAs quantum dots — •U. W. Pohl, A. Schliwa, R. Seguin, S. Rodt, K. Pötschke, and D. Bimberg — Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin

A systematic variation of the exciton fine-structure splitting ranging from above 500 µeV to -80 µeV was found in self-organized InAs/GaAs quantum dots of decreasing, well-defined sizes [1]. This finding is of basic interest for novel applications in e.g. quantum cryptography and logics. The assignment of the dependency was enabled by the recently reported multi-modal size distribution of equally shaped dots in our ensembles [2], providing a major step towards controlling the exchange interaction of confined excitons and resulting properties. We will discuss the origin of such intriguing dot ensembles and show how the comprehensive knowledge of structural dot properties advances understanding and control of excitonic properties. Comparison with model calculations allow statements on the main effects governing the electronic states, yielding the degree of correlation and piezoelectricity as key parameters being responsible for exciton binding energy and fine-structure splitting, respectively.

[1] R. Seguin et al., Size-dependent fine-structure splitting in self-organized InAs/GaAs quantum dots, Phys. Rev. Lett., in print.

[2] U. W. Pohl et al., Evolution of a multimodal distribution of self-organized InAs/GaAs quantum dots, Phys. Rev. B, in print.