Phonon Thermal Transport across Multilayer Graphene/Hexagonal Boron Nitride van der Waals Heterostructures.

Abstract

Van der Waals (vdW) heterostructures stacked vertically by graphene (Gr) and hexagonal boron nitride (h-BN), by virtue of their novel properties, will undoubtedly spark great interests from the perspective of basic physics and applied science. Herein, phonon thermal transport across multilayer Gr/h-BN vdW heterostructures was systematically investigated by extensive molecular dynamics simulations, both in terms of internal structural configuration and external modulation. The former includes the structural configuration at the Gr/h-BN interface, the proportion of components in the effective heat transfer area, and size effect, while the latter includes cross-plane strain, temperature, and interfacial coupling strength. Our results show that at 300 K it has an ultralow out-of-plane thermal conductivity of only about 8.93 MWm-1 K-1, while the Gr/h-BN interfacial thermal conductance (ITC) is up to about 300 MWm-2 K-1, and the latter can be modulated in a wide range from 0.5 to 3.5 times under cross-plane strain. The analysis of the spectral decomposition results indicates that the thermal transport across the Gr/h-BN interface depends almost entirely on low-frequency out-of-plane phonons below 10 THz and the quantum effect can be ignorable, which uncovers the physical mechanisms underlying the changes in the ITC and also points the path toward its modulation.