Tailored Bismuth Nanowires for Size-Dependent Transport Studies

Bismuth nanowires are excellent model systems to investigate the interplay of various size-dependent transport phenomena relevant for applications in thermoelectrics, spintronics or catalytics. Due to the large Fermi wavelength (l Fermi ~40 nm) and mean free paths of charge carriers (l e and l ph ~100 nm) in bismuth at room temperature, the influence of size-effects on the transport properties can be observed on nanowires of rather large diameters. Furthermore, these properties are also influenced by the fact that bismuth belongs to the class of topological insulator materials that exhibit special charge carrier transport on the material surface linked to topological states. To better understand the transport behavior, it is of utmost importance to control the nanowire properties like surface-to-volume ratio, wire diameter and wire morphology, crystal structure, material composition and, in case of nanowire assemblies, their relative alignment to one another. We present the synthesis of parallel and interconnected assemblies of bismuth nanowires with both cylindrical and conical geometry, and sizes ranging between 50 and 3500 nm. The wires are produced by electrodeposition in polymeric etched ion-track templates applying pulsed plating and an aqueous electrolyte of bismuth chloride. The electrodeposition process as well temperature-dependent Seebeck coefficient and electrical resistance measurements as a function of nanowire size and geometry will be discussed. Figure 1