Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)

O 18.72: Poster

Monday, February 25, 2008, 18:30–19:30, Poster F

In-situ Scanning Tunneling Microscope studies of the ripening process of InAs Quantum Dots on GaAs during Growth in the MOVPE — •M. Guderian, R. Kremzow, M. Pristovsek, and M. Kneissl — TU Berlin, Institut für Festkörperphysik, EW 6-1, Hardenbergstr. 36, D-10623 Berlin, Germany

Quantum dots (QD) are highly interesting for a number of different applications, like single photon emitters or semiconductor lasers. For industrial applications these optoelectronic devices are mainly grown by metal organic vapour phase epitaxy (MOVPE) systems which allows mass fabrication. QD growth has been studied intensely, but the understanding of the mechanisms responsible for the formation of the QDs and especially of the ripening process is still poor. In order to investigate the dynamics of the ripening process and to clarify the theory of QD ripening we employed our novel in-situ scanning tunnelling microscope (STM) technique which allows measurements directly during MOVPE growth. In this presentation we will discuss the ripening process of InAs QDs on GaAs(001):Si at 475^∘C where the development of the surface was analysed directly with the in-situ STM. Ex-situ AFM measurements showed a big scattering of the data, due to different substrates and varying cooling rates, while the in-situ measurements showed clear trends in RMS roughness and size distributions. E.g. the dot density decreased proportional to e⁻¹ while the average dot size increased. In comparison of different ripening theories our experimental result follows the classical Ostwald ripening theory for the InAs on GaAs(001):Si system.