Thermal conductivity of multilayer dielectric films from molecular dynamics simulations

Abstract

Reducing heat dissipation across nanometer-thick dielectrics is critically important for the self-heating behavior of nanoelectronic devices such as phase change memory. In this paper, we perform molecular dynamics simulations to study the thermal conductivity of multilayer dielectric films consisting of SiO2 and Al2O3. We show that the thermal conductivity of SiO2/Al2O3 multilayer structures can be significantly reduced as compared to that of the bulk dielectrics. The thermal conductivity calculations of crystalline and amorphous multilayer structures with different period thicknesses are presented as well as the size effects. The results show the thermal transport across the crystalline SiO2/Al2O3 multilayer structures is dominated by diffuse interface scattering between thin films, while the internal phonon-phonon scattering dominates the thermal conductivity of amorphous multilayer structures. Thickness dependence are observed for the crystalline multilayer dielectric structures but not in the amorphous structures, which can be attributed to the phonon localization by the lattice termination/deformation at interfaces between crystalline films.