Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 42: Nanostructures at surfaces I

O 42.10: Talk

Wednesday, March 28, 2012, 12:45–13:00, MA 042

Growth phenomena of Ge nanowires grown by MBE — •Roman Bansen, Jan Schmidtbauer, Robert Heimburger, Thomas Teubner, and Torsten Boeck — Leibniz Institute for Crystal Growth, 12489 Berlin, Germany

Advances in nanotechnology with its significantly lower material consumption and quantum effects-related new semiconductor properties have led to a renewed interest in germanium, with its advantageous properties for numerous possible applications in photovoltaics, thermoelectrics and electronics.

The presentation concentrates on growth as well as in-detail characterization of Ge nanowires with a focus on basic growth characteristics and their dependencies on surface preparation methods. The nanowires were grown by MBE on Ge substrates using the VLS mechanism with Au as catalyst metal.

A range of different surface passivations was tested for their effect on nanowire growth. The unexpected results reveal that very clean and smooth surfaces make the catalyst droplets preferentially form "in-plane" nanowires, instead of growing "conventional" (out-of-plane) nanowires. Depending on the respective types of passivation, changes of the in-plane wires' growth directions can be observed. It is possible to explain the directions with the help of SEM and TEM images for the most part, and a model will be presented for the effect itself.