# Dimensionality and heat transport in Si-Ge superlattices

## TL;DR

This study explores how the dimensionality of Si-Ge structures influences heat transport, revealing size-dependent differences in thermal conductivity between planar superlattices and nanostructures.

## Contribution

It provides a detailed atomistic analysis of thermal conductivity in Si-Ge superlattices and nanostructures, highlighting the impact of period size on heat transport behavior.

## Key findings

- Cross-plane conductivity is higher in planar superlattices for periods >4 nm.
- Nanowires and dots have higher conductivity than superlattices below 4 nm.
- Size and structure significantly influence heat transport in Si-Ge systems.

## Abstract

We investigated how dimensionality affects heat transport in Si-Ge superlattices by computing the thermal conductivity of planar superlattices and arrays of Ge nanowires and nanodots embedded in Si. We studied superlattices with $\sim$10 nm periods using a fully atomistic Monte Carlo solution of the Boltzmann transport equation in the relaxation time approximation. We found that for periods larger than 4 nm, the room temperature cross-plane conductivity of planar superlattices with equally thick Si and Ge layers is larger than that of their nanowire and dot counterparts of similar sizes (up to 100\%), while the trend is reversed below 4 nm.