Theory of the thermoelectric power factor in nanowire-composite matrix structures

Abstract

We present a theory of thermoelectric transport in nanowire-composite matrix (ncm) systems, which incorporates a complete solution of the multi-subband Boltzmann equation for inelastic carrier-phonon scattering with full calculations of the ncm electronic band structure. This theory is used to investigate the thermoelectric power factor, ${P}_{\mathrm{ncm}}$, of ncm systems composed of InSb and PbTe. We find that ${P}_{\mathrm{ncm}}$ can be enhanced significantly compared to the bulk material, but that this enhancement depends sensitively on the carrier effective mass, on the height of the confining potential barrier that separates the ncm from the nanowires, and on the cross-sectional size of the ncm relative to that of the nanowires. These results suggest that care must be taken in the choice of ncm material as well as that of the nanowires in order to optimize the thermoelectric power factor of nanowire-composite structures.