  We report on thermal transport properties in 2 and 3 dimensions
interconnected nanowire networks (strings and nodes). The thermal conductivity
of these nanostructures decreases in increasing the distance of the nodes,
reaching ultra-low values. This effect is much more pronounced in 3D networks
due to increased porosity, surface to volume ratio and the enhanced
backscattering at 3D nodes compared to 2D nodes. We propose a model to estimate
the thermal resistance related to the 2D and 3D interconnections in order to
provide an analytic description of thermal conductivity of such nanowire
networks; the latter is in good agreement with Molecular Dynamic results.
