Theoretical work based on one-dimensional (1D) models indicates that Bi wires with diameter smaller than 50 nm can exhibit superior thermoelectric properties since the density of states at the Fermi level of a 1D system can be tuned to very high values. Recently, angle-resolved photoemission spectroscopy (ARPES) studies of Bi surfaces have shown that Bi nanowires support Rashba spin-orbit surface states, with high carrier densities of around 5×1012/cm
−2, that have not been considered in current models of Bi nanowires. According to our estimates, the sheath of surface charge on Bi nanowires should contribute substantially to the thermopower of Bi nanowires. We carried out an experimental study of the transport properties and thermopower of bismuth nanowire arrays (NWA) with wire diameters ranging between 60 nm and 13 nm to investigate these phenomena. The Rashba interaction is a spin orbit interaction that is important for surfaces of materials consisting of heavy ion elements; thermoelectric materials frequently consist of these elements (i.e.PbTe) because they scatter phonons and form low thermal conductivity materials.