Step-shaped bismuth nanowires with metal-semiconductor junction characteristics.

Uniform and step-shaped Bi nanowire (NW) arrays have been synthesized by electrochemical deposition inside the uniform and step-shaped nanochannels of an anodic aluminium oxide template. These Bi NWs are highly oriented and single crystalline. The current-voltage characteristics of the parallel uniform Bi nanowires show that the contacts between Bi NWs and gold film do not make significant contributions to the I-V characteristics of the step-shaped Bi NWs. The diameters of the thick segment and the thin segment of the step-shaped Bi NWs are about 70 and 40 nm, respectively. Their current-voltage characteristics show conventional metal-semiconductor junction behaviour. The approach can be exploited to produce one-dimensional metal-semiconductor junctions using step-shaped NWs consisting of other semi-metals without any external doping, which may find various applications in nanotechnology.