Enhancement of Seebeck Coefficient in Bi Nanowires by Electric Field Effect.

In this study, we investigated the electric field effect on the transport properties of a Bi nanowire. These effects were modeled by a surface potential. The electron states of Bi nanowires were numerically analyzed by effective mass equations at the T-point and L-point taking into account surface potential due to an external electric field. The Seebeck coefficients of Bi nanowires were calculated by using the Boltzmann equation with a constant relaxation time. It was found that the Seebeck coefficients increased when the sign of the surface potential parameter was negative. In particular, when the surface potential parameter was $$-$$ 1 eV and the skin depth was 10 nm in a 20-nm-diameter nanowire, the maximum absolute value of the Seebeck coefficient was larger than 1 mV/K, which was greatly improved compared to that without an external electric field. [ABSTRACT FROM AUTHOR]