Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 35: Poster I
HL 35.44: Poster
Dienstag, 8. März 2016, 15:00–19:00, Poster A
Local etching of a SiOx layer on Si(111) by Ga droplets and its influence on GaAs nanowire growth — •Tina Tauchnitz1,2, Harald Schneider1, Manfred Helm1,2, and Emmanouil Dimakis1 — 1Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden — 2cfaed, TU Dresden, 01062 Dresden, Germany
GaAs nanowires (NWs) can be grown epitaxially on Si(111) substrates in the vapour-liquid-solid mode. Typically, Au is used as catalyst, but affects the NW and substrate properties due to contamination. Thus, the self-catalyzed mode appears to be advantageous. The NW growth is initialized by the formation of Ga droplets on the substrate surface, which is normally covered by a thin SiOx layer. The yield of vertical NWs depends on the thickness and the nature of the SiOx [1], pointing out the complex interaction of the liquid Ga with the SiOx.
This work investigates the local etching of a native SiOx on Si(111) by liquid Ga droplets, a mechanism, which is thought to precede the NW nucleation. The droplet formation, the etching process, and their effect on the NW growth were studied as a function of the substrate temperature and the etching time using molecular beam epitaxy. In contrast to previous studies, the oxide etching is distinguished from the subsequent NW nucleation by inserting a thermal annealing step, during which the Ga droplets are evaporated completely from the surface. Finally, the yield of vertical NWs and the NW number density can be controlled just by choosing the appropriate conditions for the oxide etching, independent of those used for the subsequent NW growth.
[1] Matteini et al., J. Cryst. Growth 404, 2014