Paper accepted in Physical Review B

Our paper, “Influence of anisotropy on thermal boundary conductance at solid interfaces,” was just accepted into Physical Review B.  In this work, we show that crystalline anisotropy can affect the thermal boundary conductance across solid interfaces.  This is most prominent in materials with non-cubic crystal structures (i.e., Brillouin zones that can not be approximated as spherical).  The origin of the anisotropy is related to the phonon velocities in the different crystallographic directions.

Abstract

We investigate the role of anisotropy on interfacial transport across solid interfaces by measuring the thermal boundary conductance from 100 – 500K across Al/Si and Al/sapphire interfaces with different substrate orientations. The measured thermal boundary conductances show a dependency on substrate crystallographic orientation in the sapphire samples (trigonal conventional cell) but not in the silicon samples (diamond cubic conventional cell). The change in interface conductance in the sapphire samples is ascribed to anisotropy in the Brillouin zone along the principle directions defining the conventional cell. This leads to resultant phonon velocities in the direction of thermal transport that vary nearly 40% based on crystallographic direction.