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 Lee2 — 1Technische 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.