Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 10: Quantum Dots and Wires: Preparation and Characterization II (mainly Arsenides)
HL 10.4: Talk
Monday, March 26, 2012, 12:00–12:15, EW 202
Fabrication of ultra-low density GaAs quantum dots by filling of self-organized nanoholes — •David Sonnenberg, Andreas Graf, Vera Paulava, Achim Küster, Christian Heyn, and Wolfgang Hansen — Institut für Angewandte Physik, Universität Hamburg, 20355 Hamburg, Germany
We use the local droplet etching (LDE) technique to drill self-organized nanoholes into AlGaAs surfaces using molecular beam epitaxy. We fabricate quantum dots (QDs) by subsequent filling of these nanoholes. Here, we report on the control of the nanohole density to fabricate ultra-low densitiy QDs down to 6·106 cm−2. Using Al droplets for etching, non-optimized process parameters yield a broad hole depth distribution with shallow (depth of some nanometers) and deep (deeper than 10 nm) holes. By optimizing the arsenic background flux, the generation of shallow holes can be suppressed and only deep holes (>20 nm) remain with a strongly reduced density. Ultra-low density GaAs QDs generated by filling of the nanoholes demonstrate intensive optical emission and clear excitonic features.