Molecular dynamics of heat transfer in Si/Ge superlattices
Sebastian Volz, Jean-Bernard Saulnier, Giang Chen, Pierre Beauchamp
The effective thermal conductivity of devices including superlattice structures is mostly governed by the phonon confinement effect and interface resistance. While the confinement is reasonably well described in the phonon wave picture, the energy transfer mechanisms at interfaces remain unclear. An atomic study was carried out to overcome the complexity of phonon-based models by the molecular dynamics technique. Multilayer configurations were simulated, corresponding to the epitaxial deposition of Si/Ge superlattices on silicon substrates by the use of the conjugate gradient method, to minimise the structure energy. Results without the conjugate gradient method are also presented. The cross-plane heat flux and thermal conductivity are then deduced for both cases and the observed discrepancies are discussed.