Peculiarities of size effect manifestation in thermopower and resistance at electron topologic transitions induced by doping and elastic stretch in bismuth based nanowires

In the present work, by elastic stretch, electron topologic transitions (ETT) of different kinds were realized in nanowires of pure and doped bismuth, and anomalies accompanying them in kinetic characteristics (thermopower and resistance) were investigated. For the first time the thermopower α of a single wire with d = 70 nm was measured, at 80 K α = 86 μV/K. In the nondeformated state the size effect of thermopower on the pure bismuth wires was shown. It consists in sign inversion (from (-) to (+)) in the temperature range 80-210 K and formation of positive maximum achieving the maximum value for wires with minimal diameter. At the ETT caused by stretch the sign inversion occurs again, from (+) to (-) in this case. The main features of the thermopower change at the stretching and diameter alteration are associated with the intervalley processes of the surface scattering. A mixed influence of doping and deformation on bismuth wires with different diameters allowed to observe peculiarities of thermopower and resistance at different ETT kinds of in conditions of the size effect manifestation.