Thermal conductivity of interconnected silicon nanoparticles: Application to porous silicon nanostructures

A model describing phonon heat conduction in silicon nanowires formed by interconnected nanoparticles is developed from basic principles of the elementary kinetic theory of gases. The thermal transport in a network of the interconnected nanoparticles forming a nanowire is found to be mainly controlled by the interconnection area. In particular, thermal conductivity of the network is strongly dependent on the ratio of the nanoparticle dimension to the interconnection one. Contrary to the case of classical silicon nanowires having a constant section dimension, the thermal conductivity of the interconnected nanoparticles with a given interconnection dimension decreases along with the nanoparticle dimension increase. The model is applied for thermal transport analysis in porous silicon (PS) nanostructures. In particular, it allows, for the first time, deducing of new structural information on PS nanoscale skeleton such as porosity dependent interconnection dimension and percolation strength of the nanoparticle network.