Thermoelectric Nanowires Based on Bismuth Telluride

Abstract

Bismuth antimony telluride (BixSb2-xTe3) and bismuth tellurium selenide (Bi2Te3-xSex) nanowires, witha 60nmdiameter, have been potentiostatically electrodeposited from perchloric baths using anodic alumina membrane. For n-type nanowires, gradual selenium concentration studies have established which one gives the closest stoichiometry to Bi2Te2.7Se0.3. Seebeck coefficients reached-70μV/K after annealing. For p-type nanowires, some samples show Seebeck coefficients higher than +160μV/K. Nanowires morphology and stoichiometry were investigated by SEM and EDX, while structure and phases were determined by XRD.First electrical conductivity measurements exhibit a high resistivity for p-type nanowires.The problem of contact resistance between nanowires and metals is revealed through the resistance measurement of single and assembled nanowires.This work reveals the strong dependence of nanowires chemical composition and morphology on deposition potential. For the low deposition over-potential, the deposition rate is fairly slow and nanowires are highly oriented with a compact cylindrical aspect; whereas for higher deposition over-potentials, fast growth rate leads to dendritic polycrystalline structures.