Structural, Dynamic, and Vibrational Properties during Heat Transfer in Si/Ge Superlattices: A Car-Parrinello Molecular Dynamics Study

TL;DR

This study uses Car-Parrinello molecular dynamics to analyze heat transfer mechanisms in Si/Ge superlattices, revealing the role of low-frequency phonons in coherent heat conduction and providing insights into thermophysical properties.

Contribution

It introduces a quantum mechanical molecular dynamics approach to investigate heat transfer in Si/Ge superlattices, highlighting phonon contributions and structural dynamics.

Findings

Low-frequency phonons facilitate coherent heat conduction.

Structural changes relate to heat transfer mechanisms.

The simulation results align with thermophysical expectations.

Abstract

The structural, dynamic, and vibrational properties during the heat transfer process in Si/Ge superlattices, are studied by analyzing the trajectories generated by the ab initio Car-Parrinello molecular dynamics simulation. The radial distribution functions and mean square displacements are calculated and further discussions are made to explain and probe the structural changes relating to the heat transfer phenomenon. Furthermore, the vibrational density of states of the two layers (Si/Ge) are computed and plotted to analyze the contributions of phonons with different frequencies to the heat conduction. Coherent heat conduction of the low frequency phonons is found and their contributions to facilitate heat transfer are confirmed. The Car-Parrinello molecular dynamics simulation outputs in the work show reasonable thermophysical results of the thermal energy transport process and shed light on the potential applications of treating the heat transfer in the superlattices of semiconductor materials from a quantum mechanical molecular dynamics simulation perspective.