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HL: Fachverband Halbleiterphysik

HL 69: Quantum Dots and Wires: Transport Properties II (mainly Quantum Dots)

HL 69.6: Vortrag

Mittwoch, 28. März 2012, 18:30–18:45, EW 203

HRTEM investigation of InAs/GaAs sub-monolayer structures — •Felix Kießling¹, Tore Niermann¹, Jan-Hindrik Schulze², Tim David Germann², André Strittmatter², Udo W. Pohl², Dieter Bimberg², and Michael Lehmann¹ — ¹Institut für Optik und Atomare Physik, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany — ²Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany

A promising idea of achieving polarization independent quantum dots (QD) is the deposition of InAs-sub-monolayers (SML) above Stranski-Krastanov In_xGa_1−xAs-QDs. The strain of the QDs influences the growth of the SML stacks. We studied stacks of ten nominal 0.18 nm thick SML of InAs above In_0.26Ga_0.73As QDs in a CS-corrected FEI Titan 80-300 TEM. In high-resolution TEM-images we could resolve the distinct single layers of the SML stacks. In thin areas, Geometric Phase Analysis is useful to find lattice mismatches caused by the Indium deposition. Furthermore we used the chemical sensitive (002) reflection in the systematic row to observe the Indium in the GaAs-substrate. In a specimen with 1.7 monolayer thick InAs depositions, this chemical sensitive reflection makes it possible to determine the segregation of Indium into the GaAs-substrate.

This work is supported by the DFG Collaborative Research Centre 787 "Semiconductor Nanophotonics".