Molecular Dynamics Simulations on Heat Conduction in Nano-porous Si

We investigated heat conduction in a nano-porous silicon by molecular-dynamics simulations (MDs). We calculated the phonon dispersion curves of the nanostructured Si to understand the effects of nano-structures on phonon properties, such as phonon group velocity and phonon density of states. The dispersion curves were calculated from MD's results by using the 2D time-space Fourier transformation. Frequency gaps in phonon dispersion curves reduce the phonon group velocity in the periodic nano-porous structures. Moreover the group velocity of phonon was reduced due to new phonon modes even though the nano-porous was random. The results showed that nano-porous structures reduce the thermal conductivity as well as super lattices. (C) 2011 Wiley Periodicals, Inc.