We attempted to replace the standard catalyst Au by Fe, Dy and Al. The experiments with Fe and Dy resulted in wire-like structures with high defect densities (published in: Zeitschrift für Metallkunde 96 (5), 427 (2005)). One example of silicon nanowires grown using Al on a Si(111) substrate is shown in the SEM image.
Details have been published:
Wang, Y., Schmidt, V:, Senz, S. and Gösele, U.:
Epitaxial growth of silicon nanowires using an aluminium catalyst
Nature Nanotechnology, 1, 186 (2006); doi:10.1038/nnano.2006.133