Effects of anisotropy and size of polar nano thin films on their thermal conductivity due to surface phonon-polaritons

摘要

The effects of the permittivity anisotropy and size of a nano thin film on its thermal conductivity due to surface phonon-polaritons are studied. We demonstrate that this thermal conductivity is a linear combination of the inverse first and third powers of the film thickness. For a 100-nm-thick film of α-quartz surrounded by air, the thermal conductivity along the optical axis is comparable to the phonon counterpart and equals 13 Wm~(-1) K~(-1), which is 25% higher than that along the perpendicular direction, at room temperature. Higher values are found for thinner films at higher temperatures.