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HL: Fachverband Halbleiterphysik

HL 86: Quantum Dots: Growth and Characterization

HL 86.2: Vortrag

Freitag, 18. März 2011, 10:30–10:45, FOE Anorg

Tuning the emission of GaAs and InGaAs quantum dots — •Eugenio Zallo, Paola Atkinson, Rinaldo Trotta, Armando Rastelli, and Oliver G. Schmidt — Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstrasse 20, 01059 Dresden, Germany

We report on a method to obtain unstrained GaAs/AlGaAs and InGaAs/AlGaAs quantum dots with low surface densities and widely tunable emission wavelength. We first prepare a template of self-assembled nanoholes on a GaAs(001) surface by a droplet etching step which consists of the alternate deposition of Ga and GaAs at a substrate temperature of 520 ^∘C. The template is then overgrown with a 7-10 nm thick AlGaAs layer. The resulting nanoholes, with a depth of 6-10 nm are then filled with different amounts of GaAs or InGaAs, followed by deposition of the top AlGaAs barrier. By gradually increasing the amount of GaAs we can tune the emission wavelength in the spectral range 690-780 nm. By replacing the GaAs with InGaAs, long wavelength emission can be obtained with smaller dots. The high quality of the dots is demonstrated by single-dot photoluminescence spectra, which show excitonic emission linewidths down to 25 µeV (our resolution limit). Finally, we present preliminary results on the effect produced by external biaxial stress on the emission of single initially unstrained QDs.