Synthesis and Characterization of Cadmium Telluride Nanowire

CdTe nanowires with controlled composition were cathodically electrodeposited using track-etched polycarbonate membrane as scaffolds and their material and electrical properties were systematically investigated. As-deposited CdTe nanowires show nanocrystalline cubic-phase structures with grain size of up to 60 nm. The dark field images of nanowires reveal that the crystallinity of nanowires was greatly improved from nanocrystalline to a few single crystals within nanowires upon annealing at 200°C for 6 hrs in a reducing environment (5 % H₂ + 95 % N₂). For electrical characterization, single CdTe nanowire was assembled across microfabricated gold electrodes using drop-casting method. In addition to increase in grain size, the electrical resistivity of an annealed single nanowire (a few 10⁵ ohm cm) was one order of magnitude greater than as-deposited nanowire indicating that crystallinity of nanowires improved and defects within nanowires were reduced during annealing. By controlling the dopants levels (e.g. Te content of nanowires), the resistivity of nanowires were varied from 10⁴ to 10⁰ ohm cm. Current-voltage (I-V)characteristics of nanowire indicated the presence of Schottky barriers at both ends of the Au/CdTe interface. Temperature dependent I-V measurements show that the electron transport mode was determined by a thermally activated component at T>-50°C and a temperature independent component below -50°C. Under optical illumination, the single CdTe nanowire exhibited enhanced conductance.