The effect of lifetime broadening on the conductivity and thermopower of a quasi-1D wire

Abstract

The density of states, conductivity and thermopower are calculated via Green function methods for a quasi-1D wire with elastic scattering from static impurities. The results are compared with those of standard Boltzmann transport theory and the modifications due to lifetime broadening are demonstrated. In the low-impurity limit the results are shown to reduce to those of Boltzmann theory, with large quantum-size effects (QSE) predicted. As the impurity concentration increases, the effects of broadening become more important until for k_Fl approximately=5 the QSE in the conductivity are found to have effectively disappeared. The QSE in the thermopower are less affected by the broadening with significant structure still expected for k_Fl approximately=5, the thermopower changing sign when the chemical potential is near a sub-band minimum for T<or approximately=6K.