Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 7: Semiconductor substrates

O 7.6: Vortrag

Montag, 23. März 2009, 12:30–12:45, SCH A315

Structural properties of sub-monolayer InAs-coverages on GaAs(001) — •Christopher Prohl, Britta Höpfner, Jan Grabowski, Holger Eisele, and Mario Dähne — Institute of Solid State Physics, Technical University Berlin, Germany

Even if InAs/GaAs is the model system for III-V-semiconductor quantum dots, the growth and dot formation is still not understood in detail. In this work, we investigated low InAs coverages in the sub-monolayer range to understand the growth of InAs on GaAs and to receive a databasis, also for further investigation of quantum dots and their capping. Molecular beam epitaxy (MBE) was used to prepare different samples with increasing sub-monolayer InAs-coverages on a GaAs(001) wafer. The growth was performed on both As-rich reconstructions, the c(4x4) and the β2(2x4). Using in-situ scanning tunneling microscopy (STM) with atomic resolution, the formation of an InAs/GaAs- layer was investigated step by step, from the clean GaAs surface up to about one monolayer coverage of InAs. It was found that InAs first grows directly on boundaries of different c(4x4) domains. Further on, it then sticks to the hollow sites of perfectly c(4x4) reconstructed areas of GaAs(001). Continuing growth leads to a complete monolayer but with a new reconstruction for both the c(4x4) and the β2(2x4) reconstructed surface. The authors thank K. Jacobi and the MPG for providing the experimental set-up. This work was supported by project Da 408/12 of the DFG.