Single-Crystalline, Stoichiometric Bi2Te3 Nanowires for Transport in the Basal Plane

Bi 2 Te 3 nanowires were grown in a nanostructured Al 2 O 3 matrix by potential-pulsed electrochemical deposition. The wires had diameters of 50 nm to 80 nm and length of about 56 μ m. Cross-sections prepared for scanning electron microscopy revealed uniform growth with deviations in length of less than 10%. The wires were deposited with reduction potentials between −150 mV and −250 mV. A reduction potential of −200 mV yielded an average Te content of 63.2 at.% as determined by calibrated, high-accuracy energy-dispersive x-ray spectrometry in transmission electron microscopy (TEM). The chemical composition was uniform along the length of the nanowires but depended on their diameter. The Te content increased by about 1 at.% when the diameter of the nanowires decreased from 80 nm to 50 nm. Selected-area electron diffraction combined with dark-field TEM imaging revealed single-crystalline wires; no grain boundaries were detected. The nanowires grew along the [110] and [210] directions; the c axis was perpendicular to the wire axis, allowing basal plane transport unaffected by grain boundaries.