Study of phonon transport across Si/Ge interfaces using Full-Band phonon Monte Carlo simulation

Abstract

A Full Band Monte Carlo simulator has been developed to consider phonon transmission across interfaces disposed perpendicularly to the heat flux. This solver of the Boltzmann transport equation does not require any assumption on the shape the phonon distribution and can naturally consider all phonon transport regimes from the diffusive to the fully ballistic regime. This simulator is used to study single and double Si/Ge heterostructures from the micrometer scale down to the nanometer scale, i.e. in all phonon transport regime from fully diffusive to ballistic. A methodology to determine the thermal conductivity at thermal interfaces is presented.

Spectral Simulation of Heat Transfer Across Polytype Interfaces

“…Thus, these modal flux contributions are dependent on the transport regimes and can be used as a local indicator of non-equilibrium transport if the contributions differ from those expected near equilibrium, i.e., in a diffusive transport regime. [23] The modal contribution profiles shown in Figure 8 are actually symmetrical when the thermostats are inverted (meaning T H : Ge 2H / T C : Ge 3C instead of T H : Ge 3C / T C : Ge 2H). The result of this configuration (not shown) is the exact mirror image of Figure 8.…”

“…This is instrumental in computing a coherent G int value. [23] Figure 3 illustrates the types of devices investigated here:…”

“…In this work, a homemade Full Band Monte Carlo simulator [22,23] dedicated to the phonon transport has been used to investigate the thermal transport across simple and multiple 3C/2H polytype interfaces of Silicon and Germanium. The material properties such as the phonon dispersion and relaxation rates in the 3D Brillouin zone (BZ) were computed using ab-initio computation.…”

“…The material properties such as the phonon dispersion and relaxation rates in the 3D Brillouin zone (BZ) were computed using ab-initio computation. [24] The phonon transmission across interfaces was implemented in the Full Band Monte Carlo simulator for phonons, [22,23] by using a Full-band version of the Diffusive Mismatch Model (DMM). [25,26] The present work focuses on the spectral and modal properties of transport to locally characterize the out of equilibrium phonon transport regime occurring around the interfaces.…”

“…The material properties such as the phonon dispersion and relaxation rates in the 3D Brillouin zone (BZ) were computed using ab‐initio computation. [ 24 ] The phonon transmission across interfaces was implemented in the Full Band Monte Carlo simulator for phonons, [ 22,23 ] by using a Full‐band version of the Diffusive Mismatch Model (DMM). [ 25,26 ]…”