Bismuth quantum-wire arrays fabricated by a vacuum melting and pressure injection process

Ultrafine bismuth nanowire arrays were synthesized by injecting its liquid melt into nanochannels of a porous anodic alumina template. A large area (1 cm X 1.5 cm) of parallel wires with diameters as small as 13 nm, lengths of 30-50 μm, and packing density as high as 7.1 X 10¹⁰ cm^-2 has been fabricated. X-ray diffraction patterns revealed these nanowires, embedded in the insulating matrix, to be essentially single crystalline and highly oriented. The optical absorption spectra of the nanowire arrays indicate that these bismuth nanowires undergo a semimetal-to-semiconductor transition due to two-dimensional quantum confinement effects.