Hamburg 2001 – scientific programme
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DS: Dünne Schichten
DS 2: Oberfl
ächenmodifizierung II
DS 2.2: Talk
Monday, March 26, 2001, 10:30–10:45, S 5.1
Template-Directed Ion Beam Synthesis of Ge Nanowires using V-Grooves — •Torsten Müller, Karl-Heinz Heinig, Bernd Schmidt, Arndt Mücklich, and Wolfhard Möller — Forschungszentrum Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, PO-BOX 510119, 01314 Dresden, Germany
Guided self-organization of Ge nanowires in templates has been studied experimentally and theoretically. V-grooves formed in (001)Si by anisotropic etching with 30% KOH at 80∘C. About 200 nm were grown on the (001)Si wafer surface and on the (111)Si V-groove sidewalls by oxidation at 1000∘C in dry O2. The resulting SiO2-V-grooves were used as templates for the Ge nanowire fabrication. Ge+ ions have been implanted into the SiO2 at 70 keV with a fluence of 1017 cm−2. The theoretically predicted enrichment of Ge in the V-groove bottom during homogeneous ion implantation has been proven by analytic TEM (EDX). Annealing of Ge+ implanted samples in N2 leads to phase separation of Ge from the SiO2 matrix. Cross sectional TEM studies have confirmed the self-organization of a Ge nanowire in the SiO2 at the V-groove bottom, whereas only a thin layer of isolated Ge nanoclusters has been found in the V-groove sidewalls. The kinetics of the wire formation during annealing was studied 3D Kinetic Lattice Monte-Carlo simulations. The comparison to experimental results reveals self-organization phenomena during phase separation, caused by nucleation, Ostwald ripening and coalescence. Moreover, the simulations were used to study the stability of very thin Ge nanowires against thermal fluctuations.