Geometrical effect of thermal conductivity in 2D silicon films with periodic nanopores

Abstract

2D nanoporous silicon films (np-SiFs) are of great interest as a kind of platform system for thermoelectric materials. In this study, the thermal conductivity (TC) of periodic np-SiFs was investigated systematically in relation to their geometric parameters, including pore radius, pore period length, and film thickness in terms of the atomic-bond-relaxation correlation mechanism and continuous medium mechanics by using the phonon kinetic method with the Born–von Karman dispersion relation. It was found that the 2D np-SiFs with columnar nanopores have high surface-to-volume ratios and elastic interactions among nanopores, which will change the Debye temperature, modify the phonon dispersion relation, reduce phonon group velocity, and further lead to the reduction of TC. Our findings provide a fundamental insight into nanoscale thermal transport in nanoporous structures, and are also useful for the advance rational design of novel thermoelectric devices.