Phonon non-equilibrium effects on interface thermal resistance between graphene and substrates

Abstract

Accurate measurement and deep understanding of interfacial thermal transport through interfaces where two-dimensional (2D) materials are involved are crucial for efficient thermal management in nanodevices. However, there is still a large discrepancy in the measurement on the interfacial thermal resistance (ITR) at interfaces between 2D materials and substrates. In this study, two kinds of molecular dynamics techniques are utilized to investigate the ITR of graphene/silicon interfaces under steady-state and transient conditions. Our results indicate that, in both conditions, phonon non-equilibrium phenomena could lead to an overestimation of the interfacial thermal resistance. In the steady state, the overestimation of ITR arises from an exaggerated interfacial temperature difference when using specific vibrational modes as indicators of the sample temperature. In the transient regime, it is attributed to the extended thermal relaxation time of flexural acoustic modes in graphene caused by weak phonon coupling when recording the temperature evolution to extract the ITR. These findings provide a comprehensive understanding of thermal transport across the graphene/silicon interface, aiding in the optimization of graphene-based nanodevices. The study also underlines the necessity of considering the specific experimental setup and physical processes involved when interpreting ITR data obtained from measurements.