Numerical simulation of thermal conductivity of SiNW-SiGe_0.3 composite for thermoelectric applications

The electron band structure and phonon energy dispersion of the silicon nanowires (SiNWs) embedded in SiGe_0.3 (SiNW-SiGe_0.3 composite) are simulated by using the effective mass Schrödinger equation and the elastodynamic wave equation, respectively. Then, the TE properties of the SiNW-SiGe_0.3 composite are investigated by the Landauer approach. The simulation shows the contribution from electrons/holes on both electrical conductance and thermal conductance increases few times by introducing SiNWs, but on the other hand, lattice thermal conductance reduces around two orders. These results are consistent with the experimental measurement and indicates that much lower lattice thermal conductance dominates the TE performance of the SiNW-SiGe_0.3 composite.