Effect of impurities on charge and heat transport in tubular nanowires.

We calculate the charge and heat currents carried by electrons, originating from a temperature gradient and a chemical potential difference between the two ends of tubular nanowires with different geometries of the cross-sectional areas: circular, square, triangular, and hexagonal. We consider nanowires based on InAs semiconductor material, and use the Landauer-Büttiker approach to calculate the transport quantities. We include impurities in the form of delta scatterers and compare their effect for different geometries. The results depend on the quantum localization of the electrons along the edges of the tubular prismatic shell. For example, the effect of impurities on the charge and heat transport is weaker in the triangular shell than in the hexagonal shell, and the thermoelectric current in the triangular case is several times larger than in the hexagonal case, for the same temperature gradient.

Thermoelectric properties of tubular nanowires in the presence of a transverse magnetic field.

We calculate the charge and heat current associate with electrons, generated by a temperature gradient and chemical potential difference between two ends of a tubular nanowire of 30 nm radius in the presence of an external magnetic field perpendicular to its axis. We consider a nanowire based on a semiconductor material, and use the Landauer-Büttiker approach to calculate the transport quantities. We obtain the variation of the Seebeck coefficient (S), thermal conductivity (κ), and the figure of merit (ZT), with respect to the temperature up to 20 K, and with the magnetic field up to 3 T. In particular we show that the Seebeck coefficient can change sign in this domain of parameters. In addition κ and ZT have oscillations when the magnetic field increases. These oscillations are determined by the energy spectrum of the electrons.