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HL: Fachverband Halbleiterphysik

HL 44: Quantum dots: Preparation and characterization

HL 44.2: Vortrag

Mittwoch, 18. März 2015, 09:45–10:00, EW 203

Growth and structure of In_0.50Ga_0.50Sb quantum dots on GaP — •Elisa Maddalena Sala, Gernot Stracke, Andre’ Strittmatter, and Dieter Bimberg — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany

III-V self-assembled QDs on GaP have recently attracted great interest for application in nano memory cells. As demonstrated by Marent, Geller and Bimberg et al, such QDs can be employed as storage units in a novel type of non-volatile nano memory, the QD-Flash. In this context, a proper choice of QD material is of decisive importance: by embedding In_0.50Ga_0.50Sb QDs in a GaP matrix, storage times of more than 10 years can be obtained. Here we demonstrate the Stranski-Krastanov (S-K) growth of In_0.50Ga_0.50Sb QDs on GaP(001) in metalorganic vapor phase epitaxy (MOVPE) environment for the first time. As reported in our previous works on InGaAs/GaP, a thin GaAs interlayer prior to QD deposition plays a decisive role in the surface energetics. In_0.50Ga_0.50Sb QD growth is partially suppressed for GaAs coverage of less than 5 ML. Utilizing a 5 ML- thick GaAs layer, the transition from 2D to 3D growth is determined to about 0.20 ML and the QD density shows a logarithmic dependence on initial layer thickness, revealing a typical S-K growth mode. Prior to QD material deposition, a short Sb-flush is used to initiate antimony incorporation. Experimental results show that Sb apparently modifies the growth kinetics by reducing the surface diffusion length of gallium and indium atoms.