Thermal Boundary Conductance and Phonon Transmission in Hexagonal Boron Nitride/Graphene Heterostructures

Abstract

Two‐dimensional (2D) materials such as graphene and hexagonal boron nitride (h‐BN) have attracted interest as a conductor/insulator pair in next‐generation devices because of their unique physical properties; however, the thermal transport at the interfaces must be understood to accurately predict the performance of heterostructures composed of these materials. Time‐domain thermoreflectance (TDTR) is used to estimate the thermal boundary conductance (TBC) at the interface of h‐BN and graphene to be 34.5 (+11.6/−7.4) MW m−2 K−1. The advantage of TDTR is that it does not need to create a large temperature gradient at the interface of heterostructures, but it has not yet been used for h‐BN/graphene interface. Phonon transmission and TBC at the h‐BN/graphene interface are predicted by two different formulations of the diffuse mismatch model (DMM) for anisotropic materials. The analysis of phonon transmission and temperature dependence of TBC establishes the flexural branch in the ab‐plane, and the c‐plane longitudinal acoustic branch of graphene and h‐BN are the dominant contributors when implementing both the DMM models. The methodology developed herein can be used to analyze heterostructures of other 2D materials.

Interfacial Coordination Interaction Enables Soft Elastomer Composites High Thermal Conductivity and High Toughness

“…In order to more intuitively understand the effect of silver–sulfur coordination on the thermal conductivity, we used time domain thermoreflectance (TDTR) technology to test the interfacial thermal resistance between poly­(LA) and Al@Ag (Figure C). ,− The TDTR technique measures the transient thermal response of laser heating on the sample surface by periodically heating the sample surface (pump beam) and monitoring its temperature variation via thermoreflectance (probe beam) (Figure D). The phase signal profile illustrates a clear difference in interfacial thermal resistance (Figure S16).…”

Ultrasensitive Calorimetric Measurements of the Electronic Heat Capacity of Graphene

“…26,27 We have only considered acoustic phonons of graphene 37 because its optical phonons 23,28 and hBN's phonon polaritons 22,38 are not expected to play a role here given ΔT e is much less than T L in G th measurements. Furthermore, because of the large thermal conductance between the graphene lattice and hBN lattice, 27,37,39,40 the increase in T L in our experiments is negligibly small ∼10 mK [see Supporting Information]. The hot electron diffusion length…”

“…We have only considered acoustic phonons of graphene because its optical phonons , and hBN’s phonon polaritons , are not expected to play a role here given Δ T e is much less than T L in G th measurements. Furthermore, because of the large thermal conductance between the graphene lattice and hBN lattice, ,,, the increase in T L in our experiments is negligibly small ∼10 mK [see Supporting Information]. The hot electron diffusion length is the distance hot electrons diffuse before thermally relaxing via phonon scattering; here G ep is the component of G th contributed by electron–phonon scattering, normalized by channel area A .…”