EFFECT OF GERMANIUM CONCENTRATION ON THE LATTICE THERMAL CONDUCTIVITY FOR SiGe ALLOY NANOWIRES

Abstract

The thermal conductivities of Si1−xGex nanowires (NWs) synthesized with Ge concentrations of 0.0%, 0.4%, 4%, and 9% and different diameters were measured from 0 to 450 K using Debye-Callaway model modified to include both longitudinal and transverse phonon modes explicitly has been developed to describe the lattice thermal conductivity for SiGe alloy nanowires as a function of nanowire diameter, alloy concentration, and temperature, obtaining a satisfactory quantitative agreement with experimental results. The model uses nanowires boundary, defects and umklapp and normal phonon-scattering parameters that scaled in a consistent manner with Debye temperature and phonon velocity from their related melting point. The results indicated that the weaker diameter dependence of the thermal conductivity recently observed in Si1−xGex nanowires (x