Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 43: Poster Session: Quantum Dots and Wires - Preparation and Characterization / Devices (incl. Laser) / Ultrafast Phenomena
HL 43.1: Poster
Dienstag, 27. März 2012, 09:30–12:30, Poster D
Lattice parameters and strain-accommodation in mixed zinc-blende/ wurtzite GaAs nanowires on Si — •Ullrich Pietsch1, Andreas Biermanns1, Steffen Breuer2, Anton Davydok1, Achim Trampert2, and Lutz Geelhaar2 — 1Universität Siegen, Festkörperphysik, Germany — 2Paul-Drude-Institut für Festkörperelektronik, Berlin, Germany
In this contribution we present a x-ray diffraction study of the interface structure of GaAs nanowires grown on Si(111)-substrates using the Ga-assisted growth mode in molecular beam epitaxy. Under the used growth conditions, NW growth starts with a large abundance of wurtzite structural units, but the zinc-blende structure dominates for longer growth times. Using grazing incidence diffraction, the wurtzite type GaAs in the NWs is found to exhibit a smaller inplane-lattice parameter than the corresponding zinc-blende type material. Using the applied growth mechanism, no pseudomorphic growth is obtained for NW-diameters down to 10nm. Instead, thin NWs grow relaxed, whereas for thicker NWs the plastic relaxation is incomplete. Although NWs grow dislocated, complete relaxation is hindered by a rough interface structure. This rough interface structure is likely caused by the initial etching-reaction of the liquid Ga droplets with the Si surface. Using asymmetric x-ray diffraction on single NWs, we measure both the in- and out-of-plane components of the displacement field caused by the incomplete relaxation process. Here, large fluctuations between different NWs are found, indicating that the detailed displacement field crucially depends on the (random) interface structure.