Direct growth of compound semiconductor nanowires by on-film formation of nanowires: Bismuth telluride

Bismuth telluride (Bi2Te3) nanowires are of great interest as nanoscale building blocks for high-efficiency thermoelectric devices. Their lowdimensional character leads to an enhanced figure-of-merit (ZT), an indicator of thermoelectric efficiency. Herein, we report the invention of a direct growth method termed On-Film Formation of Nanowires (OFF-ON) for making high-quality single-crystal compound semiconductor nanowires, that is, Bi2Te3, without the use of conventional templates, catalysts, or starting materials. We have used the OFF-ON technique to grow single crystal compound semiconductor Bi2Te3 nanowires from sputtered BiTe films after thermal annealing at 350 °C. The mechanism for wire growth is stress-induced mass flow along grain boundaries in the polycrystalline film. OFF-ON is a simple but powerful method for growing perfect single-crystal compound semiconductor nanowires of high aspect ratio with high crystallinity that distinguishes it from other competitive growth approaches that have been developed to date.