Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 77: Quantum Dots and Wires: Optical Properties II (mainly Luminescence and Electronic Structure)
HL 77.4: Vortrag
Donnerstag, 29. März 2012, 10:15–10:30, EW 203
Excitonic lifetimes in single GaAs quantum dots fabricated by local droplet etching — •Christian Heyn1, Christian Strelow2, and Wolfgang Hansen1 — 1Institute of Applied Physics, University of Hamburg, D-20355 Hamburg, Germany — 2Institute of Physical Chemistry, University of Hamburg, D-20146 Hamburg, Germany
We fabricate GaAs quantum dots (QDs) embedded in an AlGaAs matrix by filling of nanoholes, that are drilled in an AlAs/AlGaAs heterostructure surface utilizing self-assembled Al droplet etching. The time-dependent optical emission of the QDs is studied using single-dot photoluminescence (PL) spectroscopy with quasi resonant excitation into the QD d-shell. The analysis of the time-dependent PL data yields a lifetime of 390 ps for excitons and 426 ps for biexcitons. In comparison to most other types of self-assembled QDs, the present GaAs QD lifetimes are short, which we attribute mainly to the influence of the emission energy. We describe the time dependent PL data by a three-level rate model, that quantitatively reproduces both the experimental decay times and the influence of the excitation power on the absolute exciton and biexciton peak intensities.