The effect of the long-range order in a quantum dot array on the in-plane lattice thermal conductivity

Abstract

Semiconductor quantum dot superlattices consisting of arrays of quantum dots have shown great promise for a variety of device applications, including thermoelectric power generation and cooling. In this paper we theoretically investigate the effect of long-range order in a quantum dot array on its in-plane lattice thermal conductivity. It is demonstrated that the long-range order in a quantum dot array enhances acoustic phonon scattering and, thus leads to a decrease of its lattice thermal conductivity. The decrease in the ordered quantum dot array, which acts as a phonon grating, is stronger than that in the disordered one due to the contribution of the coherent scattering term. The numerical calculations were carried out for a structure that consists of multiple layers of Si with layers of ordered Ge quantum dots separated by wetting layers and spacers.