Thermal boundary resistance at Si/Ge interfaces determined by approach-to-equilibrium molecular dynamics simulations

TL;DR

This study uses molecular dynamics simulations to measure and analyze the thermal boundary resistance at Si/Ge interfaces, revealing how interface structure and heat flow direction influence thermal transport properties.

Contribution

It introduces a method to determine bulk thermal boundary resistance at Si/Ge interfaces and explores how interface modifications affect thermal rectification.

Findings

Bulk thermal boundary resistance is approximately 3.76x10^{-9} m^2 K/W for sharp interfaces.

Introducing a SiGe alloy layer reduces the thermal boundary resistance.

Thermal rectification is significant and decreases with interface moderation.

Abstract

The thermal boundary resistance of Si/Ge interfaces as been determined using approach-to-equilibrium molecular dynamics simulations. Assuming a reciprocal linear dependence of the thermal boundary resistance, a length-independent bulk thermal boundary resistance could be extracted from the calculation resulting in a value of 3.76x10$^{-9}$ m$^2$ K/W for a sharp Si/Ge interface and thermal transport from Si to Ge. Introducing an interface with finite thickness of 0.5 nm consisting of a SiGe alloy, the bulk thermal resistance slightly decreases compared to the sharp Si/Ge interface. Further growth of the boundary leads to an increase in the bulk thermal boundary resistance. When the heat flow is inverted (Ge to Si), the thermal boundary resistance is found to be higher. From the differences in the thermal boundary resistance for different heat flow direction, the rectification factor of the Si/Ge has been determined and is found to significantly decrease when the sharp interface is moderated by introduction of a SiGe alloy in the boundary layer.