Spatial Manipulation of Thermal Flux in Nanoscale Films

Increased surface-to-volume ratio is the key thermal transport determinant in nanoscale thin films and yet the impact of surface features on thermal conduction remains largely unexplored. In this work, we aim to uncover the energy flux spatial distribution in thin-film thermal conduction by developing a formulation that accounts for the existence of distinct surface conditions (roughness and correlation length) at the two interfaces. We show that designing the physical properties of thin-film surfaces provides control over the preferential spatial location of thermal flux, which could hold significant potential for rational design of thermal materials. The study highlights the importance of a rigorous description of boundary scattering mechanisms to bring in a new wave of understanding of the nature of heat at the nanoscale.