Specular reflection leads to maximum reduction in cross-plane thermal conductivity

Abstract

In contrast to established work that uses diffuse surface scattering as the mechanism to lower the in-plane thermal conductivities, we show that the largest reduction of heat conduction in thin films is achieved via specular scattering under cross-plane heat transport. Our results create a new perspective for heat conduction manipulation since smooth surfaces—in contrast to rough surfaces—are shown to be more effective in suppressing thin film heat conduction.