Role of boundary roughness in the electronic transport of Bi nanowires

Abstract

We present a study of electronic transport in 200 nm diameter bismuth nanowire arrays embedded in an alumina matrix where the nanowires are oriented preferentially with the trigonal crystalline axis parallel to the wire length. The study is based on measurements of the resistance and thermopower over a wide range of temperatures (4-300 K) as well as of magnetoresistance for fields of up to 9 T. The Fermi energies are obtained from the Landau level spectrum; results show that the wires have the intrinsic electron and hole concentrations. At high temperatures, the mobilities are temperature dependent and the electron mobility is several orders of magnitude larger than that of holes. This nanowire mobility behavior, which is also observed in the bulk, is attributed to carrier-phonon scattering. At low temperatures, the mobilities are temperature independent and roughly the same for electrons and holes. An interpretation in terms of boundary roughness scattering is proposed. © 2008 American Institute of Physics.