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Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 44: Quantum dots: Preparation and characterization

HL 44.5: Talk

Wednesday, March 18, 2015, 10:30–10:45, EW 203

Cross-sectional Scanning Tunneling Microscopy Analysis of InGaAs/GaP Quantum Dots — •Christopher Prohl1, Andrea Lenz1, Holger Eisele1, Gernot Stracke1, André Strittmatter1, Udo W. Pohl1, Dieter Bimberg1, Mario Dähne1, Yuncheng Song2, and Minjoo Larry Lee21Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany — 2Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520-8284, USA

GaP with its particular low lattice mismatch to Si offers the possibility to monolithically integrate III-V nanotechnology into Si. Recently, the topic of self-assembled InGaAs/GaP quantum dots (QDs) came more into focus because of their possible applications in new nanomemory cells. Furthermore, the first light emitting diode based on epitaxially grown InGaAs QDs on a monolithic GaP/Si substrate has already been demonstrated. In this contribution, cross-sectional scanning tunneling microscopy (XSTM) was used to structurally analyze differently grown InGaAs/GaP QDs on the atomic scale, investigating both, samples grown by metalorganic vapor-phase epitaxy (MOVPE) and molecular beam epitaxy (MBE). High-resolution images and a quantitative analysis of the local stoichiometry demonstrate that for a nominal MOVPE material amount of e.g. 3.0 monolayers (ML) GaAs and 2.0 ML In0.25Ga0.75As, indium-rich QDs with a truncated pyramidal shape, a reversed cone stoichiometry and a QD density of 2.4×1011 cm−2 form. In comparison, MBE samples with the same deposited material amount show QDs with similar size, shape and density.

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