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HL: Fachverband Halbleiterphysik

HL 32: Quantum dots and wires: preparation and characterization I

HL 32.5: Talk

Wednesday, February 27, 2008, 15:15–15:30, ER 270

InAs/GaAs(001) quantum dots, investigation of dot shape and composition with synchrotron X-ray diffraction. — •Andriy Zolotaryov, Andreas Schramm, Christian Heyn, and Wolfgang Hansen — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg

Quantum dot fabrication with molecular beam epitaxy (MBE) utilizes the three-dimensional self-organization of lattice-mismatched III-V heterostructures grown in Stranski-Krastanov mode. During MBE-growth of InAs QDs on GaAs a high amount of substrate material diffuses inside the QDs. This strongly modifies the QD strain status and thus, the process of QDs formation. The intermixing in the InAs/GaAs(001) QD systems is a complex function of growth parameters such as substrate temperature, InAs growth rate etc. and is still matter of scientific discussions. Our synchrotron X-ray studies of MBE grown InAs/GaAs(001) quantum dots reveal information about their composition and shape. The dot average chemical composition is quantitatively estimated by comparison to finite-element based calculations. A study of dots grown with varying amount of deposited InAs establishes that the composition remains constant within the whole probed InAs deposition region. Furthermore, the increase of deposited InAs amount entirely leads to a proportional increase of the surface dot density and does not significantly influence the dot size.