Effects of Vacancy Defects on Thermal Conduction of Silicon Nanowire: Nonequilibrium Green's Function Approach

Abstract

We present phonon thermal conductance calculations for silicon nanowires (SiNWs) with diameters ranging from 1 to 5 nm by nonequilibrium Green's function technique using interatomic Tersoff potential. We find that introduction of the defects reduces the thermal conductance significantly and that “center-defect” reduces thermal conductance much more than “surface defect”. We also find that the thermal conductance changes its behavior from the usual ohmic-type at room temperature, proportional to its cross-sectional area, to the unusual quantum-type at low temperature, not dependent on the cross-sectional area. The temperature for the crossover to quantized thermal conductance is found around at 100 K.