Heat Conduction in Si/Ge Superlattices: A Molecular Dynamics Study

Owing to the exceptional low thermal conductivity, Si/Ge superlattices becomes an attractive thermoelectric material to convert thermal energy into electric power. The heat conduction process in Si/Ge superlattices is studied by employing the molecular dynamics (MD) simulation in this paper. For the purpose of investigating the role of Si and Ge interface to the contribution of overall thermal conductivity reduction in Si/Ge superlattices, convergent and divergent cone nanostructures are designed as interfaces between Si layer and Ge layer. By keeping fixed temperature difference between the left and right sides of Si/Ge superlattices with constant length, the spatial distribution of temperature and temporal evolution of heat flux flowing through Si/Ge superlattices are calculated. Comparing with the Si/Ge superlattices with even interface, the nanostructured interface contributes to impede the heat conduction between Si and Ge atoms. Si/Ge superlattices with divergent cone interface presents the most excellent performance among all the simulated cases. The design of nanostructured interface paves a promising path to enhance the efficiency of Si/Ge thermoelectric material.