Heat transport in the periodically confined geometries of silicon metalattices*

The insertion of voids of nanometer size in semiconductors provides an effective and widely applicable approach to control their thermal conductivities. We have studied the thermal properties of silicon metalattices, which consist of an array of nanometer-sized pores inserted into crystalline silicon. The heat conductivity of these nanostructures has been calculated as a function of the arrangement and radius of the pores using Green-Kubo techniques with a modified Stillinger-Weber potential, revealing an extreme reduction in the thermal conductivity of two orders of magnitude for pore radii in the range of 1 to 10 nm. We have carried out a phonon-resolved analysis to explain thermal conductance of silicon metalattices and to examine its strong nonlinear dependence as a function of the volume fraction of the pores. This analysis provides guidelines for designing semiconducting nanostructures with minimal lattice thermal conductivities towards improving heat management in microelectronics and energy conversion in thermoelectrics.