Berlin 2012 – wissenschaftliches Programm
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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 InxGa1−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 In0.26Ga0.73As 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".