Lattice thermal conductivity in superlattices: molecular dynamics calculations with a heat reservoir method

We report on a molecular dynamics study of the cross-plane lattice thermal conductivity in GaAs/AlAs superlattices. The layers of the superlattice are modelled by a three-dimensional face centred cubic lattice with cubic anharmonicity, and with atomic scale roughness at the interfaces. We perform the simulation of heat flow for a section of a superlattice with high- and low-temperature thermal reservoirs attached to opposite ends. The calculation reproduces qualitatively the features observed experimentally, i.e., the dramatic reduction of the conductivity relative to the conductivity of the bulk constituent materials, and the variation of the thermal conductivity with the superlattice repeat distance. The results are also in agreement with those obtained previously by Daly et al (2002 Phys. Rev. B 66 024301) who determined the thermal conductivity from the time taken for an initially inhomogeneous temperature distribution to relax.