Seedless Growth of Sub-10 nm Germanium Nanowires

We report the self-seeded growth of highly crystalline Ge nanowires, with a mean diameter as small as 6 nm without the need for a metal catalyst. The nanowires, synthesized using the purpose-built precursor hexakis(trimethylsilyl)digermane, exhibit high aspect ratios (>1000) while maintaining a uniform core diameter along their length. Additionally, the nanowires are encased in an amorphous shell of material derived from the precursor, which acts to passivate their surfaces and isolates the Ge seed particles from which the nanowires grow. The diameter of the nanowires was found to depend on the synthesis temperature employed. Specifically, there is a linear relationship between the inverse radius of the nanowires and the synthesis temperature, which can be explained by a model for the size-dependent melting of simple metals.