Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 52: Nanostructures at surfaces: Wires, tubes

O 52.6: Vortrag

Mittwoch, 16. März 2011, 16:15–16:30, WIL B122

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

Germanium has gained renewed interest within recent years for aggressively scaled Si CMOS as well as Si photonics technologies. The reasons are given by the facts that: (i) Ge is compatible with Si process technology, (ii) it has higher hole concentration and mobility compared to many III-V semiconductor materials and (iii) its band gap value matches the wavelength of typical telecommunication infrastructure. With respect to the later application we investigated germanium nanowires as promising structures for low-band-gap photonics devices compatible with Si CMOS process technologies.

We studied the influence of different types of Ge substrates on growth direction, growth rate and shape of MBE grown Ge nanowires. In particular, homoepitaxial growth of the nanowires was compared using (100), (110) and (111) oriented germanium substrates. In all cases, the experiments revealed preferential growth in ⟨110⟩ direction. A clear dependency of the growth rate on the inclination of nanowires towards the surface normal was shown. This growth behaviour is explained by different amounts of material that contribute to nanowire growth through direct impingement on the sidewalls of the nanowire. To understand the nature of the preferential growth in ⟨110⟩ direction TEM studies are presented. Furthermore, a model is proposed to explain this behaviour.