Impact of pore anisotropy on the thermal conductivity of porous Si nanowires.

ABSTRACT: Porous materials display enhanced scattering mechanisms that greatly influence their transport properties. Metal-assisted chemical etching (MACE) enables fabrication of porous silicon nanowires starting from a doped Si wafer by using a metal template that catalyzes the etching process. Here, we report on the low thermal conductivity (κ) of individual porous Si nanowires (NWs) prepared from MACE, with values as low as 0.87 W·m^-1·K^-1 for 90 nm diameter wires with 35-40% porosity. Despite the strong suppression of long mean free path phonons in porous materials, we find a linear correlation of κ with the NW diameter. We ascribe this dependence to the anisotropic porous structure that arises during chemical etching and modifies the phonon percolation pathway in the center

SUBMITTER: Ferrando-Villalba P 

PROVIDER: S-EPMC6109058 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature