Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 44: Quantum dots: Preparation and characterization
HL 44.6: Vortrag
Mittwoch, 18. März 2015, 10:45–11:00, EW 203
Stoichiometry determination of InGaAs/GaP quantum dots — Daehwan Jung1, Christopher Prohl2, Yuncheng Song1, Minjoo Larry Lee1, and •Andrea Lenz1,2 — 1Department of Electrical Engineering, Yale University, New Haven, CT, 06511, USA — 2Technische Universität Berlin, Institut für Festkörperphysik, 10623 Berlin, Germany
InGaAs/GaP quantum dots are promising for the integration of III-V nanostructures in the well-established silicon-device technology. In order to understand and improve optoelectronic device characteristics of InGaAs quantum dots grown under various growth conditions, detailed investigations on their size, shape and stoichiometry are performed. In this presentation the stoichiometry of InGaAs quantum dots is revealed by energy dispersive X-ray spectra (EDX) in a scanning transmission electron microscope and also by cross-sectional scanning tunneling microscopy (XSTM). From XSTM images the local stoichiomety across a quantum-dot layer is determined by an evaluation of the local lattice parameter and a comparison with reference values from strain relaxation calculations. EDX and XSTM were applied on the same sample and benefit strongly from each other: It is revealed that P atoms are absent in the quantum dots and InAs is incorporated within the quantum-dot center, especially for the case of a thin GaAs layer deposited on the GaP matrix material prior to the InGaAs growth.
This work was supported by the DFG, project LE 3317/1-1.