Germanium nanowires can be used in solar cells and lithium-ion batteries, for example. To quickly fabricate large amounts of this material, supercritical fluid–liquid–solid (SFLS) or solution–liquid–solid (SLS) approaches have been used. In these processes, metal nanoparticles are used as seeds for the growth of the nanowires. The germanium first forms an eutectic alloy with the seed material and then crystallizes as a nanowire growing from the seed. However, these syntheses require high temperatures and pressures.
Justin D. Holmes, University College Cork and Trinity College Dublin, both Ireland, Christoph Marschner, Graz University of Technology, Austria, and colleagues have developed a low-temperature synthesis of germanium nanowires. The team used a solution–liquid–solid (SLS) approach with indium nanoparticle seeds and oligosilylgermane precursors.
The indium nanoparticles were added to a solution of capping agents such as trioctylphosphine oxide (TOPO) or oleylamine (OA) in a solvent with a high boiling temperature, e.g., n-dodecane or n-hexadecane. Then, precursors such as 1,1,2,2-tetrakis(trimethylsilyl)digermane or bis(trimethylsilyl)[tris(trimethylsilyl)silyl]germane were injected into the reaction mixture. The desired germanium nanowires were formed within five to ten minutes at temperatures between 180 °C and 380 °C with yields as high as 85 %.
The team characterized the nanowires using energy-dispersive X-ray analysis (EDX) and found that the product did contain roughly 1–2 % indium, but no silicon impurities from the precursors. According to the researchers, the indium-seeded Ge nanowires are particularly promising as an anode material for lithium-ion batteries.
- Rapid, Low-Temperature Synthesis of Germanium Nanowires from Oligosilylgermane Precursors,
Mohammad Aghazadeh Meshgi, Subhajit Biswas, David McNulty, Colm O’Dwyer, Giuseppe Alessio Verni, John O’Connell, Fionán Davitt, Ilse Letofsky-Papst, Peter Poelt, Justin D. Holmes, Christoph Marschner,
Chem. Mater. 2017.