Molecular Dynamics Computation of Thermal Properties in Si/Ge Nanocomposites

In this paper, an atomic scale study is carried out to characterize the thermal transport in Si/Ge nanocomposites by using the molecular dynamics (MD) simulation. The influence of size, heat flux, interface, as well as voids, on thermal properties and the inner temperature profiles of nanowire composites are studied. The results show that the thermal conductivity of nanowire composites is much lower than that of alloy, which accounts mainly for ZT enhancement and owes a great deal to the effect of interface thermal resistance. The results also indicate that a nonfourier phenomena what we call “reflecting effect” is remarkable at the Si/Ge interface, and the thermal conductivity is also dependent slightly on the bulk temperature and the specified heat flux in the range of selected system sizes and temperatures. It is also investigated that how the thermal conductivity of Si_1−xGe_x composites changes with the atomic percentage x of germanium for wire dimension of L_Si = 10 nm. Simulation results reveal that for a constant silicon wire dimension, the thermal conductivity of the Si/Ge nanocomposites increases with x. An attempt study on the influence of the voids on thermal conductivity shows that the thermal conductivity decreases with the void density. Most of the presented results from the simulations in this work come to favorable agreement with previous work, suggesting a good reliability of the present simulation method for further analysis of thermal transportation phenomena in nanocomposites and even more complex composites with pores, dislocations and impurities.