Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 44: Quantum dots: Preparation and characterization

HL 44.3: Vortrag

Mittwoch, 18. März 2015, 10:00–10:15, EW 203

Atomic structure of InAs(Sb)/GaAs submonolayer stacks — •Zeno Diemer, Andrea Lenz, Christopher Prohl, David Quandt, Udo W. Pohl, André Strittmatter, Dieter Bimberg, Mario Dähne, and Holger Eisele — Technische Universität Berlin, Institut für Festkörperphysik, 10623 Berlin, Germany

Submonolayer-grown semiconductor nanostructures are promising for high power and high speed laser devices. Recent cross-sectional scanning tunneling microscopy (XSTM) studies of InAs/GaAs submonolayer stacks have shown the formation of InAs agglomerations with lateral sizes of about 5 nm, heights of about 2 nm, and a high density above 10¹²/cm². In this work, the structural changes upon additional supply of Sb, shown by cathodoluminescence to result in a stronger localization of charge carriers, are studied on the atomic scale using XSTM. The InAs(Sb) agglomerations show slightly smaller sizes than equivalent submonolayer structures grown without Sb. From atomically resolved filled-state XSTM images the Sb incorporation could be determined simply by counting the Sb atoms. The Sb atoms are mostly incorporated in the submonolayer structures. From an analysis of the local lattice parameter the In content could be determined, being considerably smaller than the nominally deposited amount of In. Also the distance of the submonolayer stacks along growth direction is reduced by about 30% with additional Sb. These reductions from the nominal values are due to a reduced growth rate of InGaAs and GaAs on Sb-containing growth surfaces.

This work was supported by the DFG, Sfb 787, TP A2 and A4.