Thermal conductivity anisotropy in nanostructures and nanostructured materials

Thermal conductivity anisotropy is a subject for both fundamental and application interests. The anisotropy can be induced either by van der Waals forces in bulk systems or by nanostructuration. Here, we will examine four cases in which thermal anisotropy has been observed: (i) Si/Ge superlattices which exhibit higher thermal anisotropy between in-plane and cross-plane directions for the case of smooth interfaces, (ii) amorphous/crystalline superlattices with much higher anisotropy than the crystalline/crystalline superlattices and which can reach a factor of six when the amorphous fraction increases, (iii) the impact of the density of edge and screw dislocations on the thermal anisotropy of defected GaN, and (iv) the influence of the growth direction of Bi 2 Te 3 nanowires on thermal conductivity.