We report the controlled self-seeded growth of highly crystalline
Ge nanowires, in the absence of conventional metal seed catalysts, using a variety
of oligosilylgermane precursors and mixtures of germane and silane compounds
(Ge:Si ratios between 1:4 and 1:1). The nanowires produced were encased in an
amorphous shell of material derived from the precursors, which acted to isolate
the Ge seed particles from which the nanowires were nucleated. The mode
diameter and size distribution of the nanowires were found to increase as the
growth temperature and Ge content in the precursors increased. Specifically, a model was developed to describe the main stages of self-seeded Ge nanowire
growth (nucleation, coalescence, and Ostwald ripening) from the oligosilylgermane
precursors and, in conjunction with TEM analysis, a mechanism of growth
was proposed.