Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 44: Poster Session I
HL 44.40: Poster
Tuesday, March 15, 2011, 18:00–21:00, P3
Exciton-mediated lattice distortions in InAs/GaAs quantum dots — •Sebastian Tiemeyer1, Michael Bombeck2, Michael Paulus1, Christian Sternemann1, D. C. Florian Wieland1, Oliver H. Seeck3, Manfred Bayer2, and Metin Tolan1 — 1Fakultät Physik / DELTA, TU Dortmund, D-44221 Dortmund, Germany — 2Experimentelle Physik II, TU Dortmund, D-44221 Dortmund, Germany — 3HASYLAB, DESY, D-22607 Hamburg, Germany
The confinement of charge carriers to length scales comparable to the de Broglie wavelength in semiconductor heterostructures such as quantum wells and quantum dots leads to a considerable modification of the density of states (DOS). In particular quantum dots represent zero-dimensional structures possessing a DOS similar to that of atoms.
Indium Arsenide (InAs) and Gallium Arsenide (GaAs) exhibit a lattice mismatch of 7% giving rise to strain fields in quantum dot heterostructures. The strain affects significantly the electronic properties of quantum dots e.g. the band structure and band gap. Previous x-ray studies have determined the strain distribution in non-excited quantum dots and the surrounding crystalline structure. The lattice distortion by optically excited carriers has been monitored up to now only indirectly by high resolution continuous wave or non-linear time-resolved optical spectroscopy. In this study we have investigated the laser-induced strain in InAs quantum dots grown on and capped with GaAs by means of anomalous x-ray diffraction at the beamlines BL9 (DELTA, TU Dortmund) and P08 (HASYLAB, DESY Hamburg).