Two-dimensional molecular dynamics simulation of the thermal conductance of superlattices

Superlattices consist of periodic layers of thin films. Because of their unique structures and properties, they are applied in many techniques such as microelectronics, photo-electronic and thermoelectric materials etc. The present work uses non-equilibrium molecular dynamics with Lennard-Jones potential to simulate the in-plane thermal conductance of superlattices composed of two materials with equal thickness layers. The effects of equilibrium separation parameter and atomic mass on the thermal conductivity are studied. It is found that slight differences in the equilibrium separation parameter and mass between the two component layers reduce the effective thermal conductivity of the superlattices. The reduction in conductivity is attributed to the interface effects. A larger difference in the equilibrium separation parameter between the layers leads to a higher thermal conductivity, which is due to the enhanced interaction between atoms for a fixed volume system. A larger difference in mass also increases the conductivity of the superlattice, which is estimated to be the effects of the increase in specular reflection of phonons and phonon tunneling at the interface. Further increasing the difference in mass causes a reduction in the effective conductivity, which is believed to be the result of the reduction in the conductance of the layer with higher atomic mass. (C) 2000 Elsevier Science S.A. AII rights reserved.