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Open Access Nano Express

Guided self-assembly of lateral InAs/GaAs quantum-dot molecules for single molecule spectroscopy

L Wang1, A Rastelli1*, S Kiravittaya1, R Songmuang1, OG Schmidt1, B Krause2 and TH Metzger2

Author Affiliations

1 Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany

2 European Synchrotron Radiation Facility, Boîte Postale 220, F-38043, Grenoble Cedex, France

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Nanoscale Research Letters 2006, 1:74-78  doi:10.1007/s11671-006-9003-y

Published: 26 July 2006


We report on the growth and characterization of lateral InAs/GaAs (001) quantum-dot molecules (QDMs) suitable for single QDM optical spectroscopy. The QDMs, forming by depositing InAs on GaAs surfaces with self-assembled nanoholes, are aligned along the [] direction. The relative number of isolated single quantum dots (QDs) is substantially reduced by performing the growth on GaAs surfaces containing stepped mounds. Surface morphology and X-ray measurements suggest that the strain produced by InGaAs-filled nanoholes superimposed to the strain relaxation at the step edges are responsible for the improved QDM properties. QDMs are Ga-richer compared to single QDs, consistent with strain- enhanced intermixing. The high optical quality of single QDMs is probed by micro-photoluminescence spectroscopy in samples with QDM densities lower than 108 cm−2.

Lateral quantum-dot molecules; Quantum dots; Quantum dot composition; Self-assembled growth