Berlin 2012 – wissenschaftliches Programm

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KR: Fachgruppe Kristallographie

KR 9: Poster – Crystallography in Nanoscience

KR 9.1: Poster

Mittwoch, 28. März 2012, 15:00–17:30, Poster E

Phase-distribution in GaAs nanowires on Si (111) — •Andreas Biermanns¹, Steffen Breuer², Anton Davydok¹, Achim Trampert², Lutz Geelhaar², and Ullrich Pietsch¹ — ¹Universität Siegen, Festkörperphysik, Germany — ²Paul-Drude-Institut für Festkörperelektronik, Berlin, Germany

The growth of semiconductor nanowires (NWs) has attracted significant interest in recent years due to their unique properties for possible novel semiconductor devices. However, many details of the growth mechanisms are not well understood. One particular problem during NW growth is the control of crystal structure, as NWs often adapt the cubic zinc-blende (ZB) or hexagonal wurtzite (WZ) structure. In addition, ZB rotational twins and stacking faults are often observed along the NW. As the structural composition usually varies between different NWs, individual characterization of a large ensemble of as-grown wires is often desired, but experimentally challenging. In this contribution we present a x-ray diffraction study of the distribution of ZB and WZ domains in GaAs nanowires grown on Si(111) across a large surface area. The GaAs NWs were grown by the Ga-assisted growth mode in molecular beam epitaxy. Using a nanometer-sized x-ray beam at the ESRF synchrotron source, the spatial distribution of particular sensitive Bragg-reflections was monitored, showing that the NWs grow predominantly in one ZB orientation without rotational twins. Close to the bottom of the NWs, WZ inclusions can be observed, whose position along the growth axis can be determined from the diffraction profile of the corresponding NW.