Heat transfer mechanism across few-layer graphene by molecular dynamics

Shen, Meng; Schelling, Patrick K.; Keblinski, Pawel

doi:10.1103/physrevb.88.045444

Cited by 87 publications

(66 citation statements)

References 83 publications

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“…4. The as-calculated Λ z value at temperature 300 K, about 20 nm, is comparable to the 10 nm value estimated from the simplified Kinetic theory in a recent work (36). In addition, the average basal-plane mean free path calculated with this approach is even much longer than the cross-plane values, and approaches about 240 nm at room temperature, which is about one-third of the 775 nm value suggested for suspended graphene (10) based on the simplified Kinetic theory and a graphene thermal conductivity value up to a factor of 2.6 higher than the graphite basal-plane value used here.…”

Section: Discussionsupporting

confidence: 85%

Phonon-interface scattering in multilayer graphene on an amorphous support

Sadeghi¹,

Jo²,

Shi

2013

Proc. Natl. Acad. Sci. U.S.A.

148

113

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The recent studies of thermal transport in suspended, supported, and encased graphene just began to uncover the richness of twodimensional phonon physics, which is relevant to the performance and reliability of graphene-based functional materials and devices. Among the outstanding questions are the exact causes of the suppressed basal-plane thermal conductivity measured in graphene in contact with an amorphous material, and the layer thickness needed for supported or embedded multilayer graphene (MLG) to recover the high thermal conductivity of graphite. Here we use sensitive in-plane thermal transport measurements of graphene samples on amorphous silicon dioxide to show that full recovery to the thermal conductivity of the natural graphite source has yet to occur even after the MLG thickness is increased to 34 layers, considerably thicker than previously thought. This seemingly surprising finding is explained by long intrinsic scattering mean free paths of phonons in graphite along both basal-plane and cross-plane directions, as well as partially diffuse scattering of MLG phonons by the MLG-amorphous support interface, which is treated by an interface scattering model developed for highly anisotropic materials. Based on the phonon transmission coefficient calculated from reported experimental thermal interface conductance results, phonons emerging from the interface consist of a large component that is scattered across the interface, making rational choice of the support materials a potential approach to increasing the thermal conductivity of supported MLG.phonon transport | boundary scattering | nanoscale thermal transport | two-dimensional materials | thermal management A s a monoatomic layer of carbon atoms arranged in a hexagonal lattice, single-layer graphene (SLG) is the building block of graphite and carbon nanotubes (CNTs), which can be envisioned as a stack of a large number of graphene layers and rolled-up cylinders of graphene sheets, respectively. Thermal transport in these graphitic materials has intrigued researchers for several decades. The industrial use of graphite in high-temperature or high-heat flux applications motivated a number of initial studies of its thermal properties. These studies have found highly anisotropic thermal transport properties in graphite, where the basal-plane thermal conductivity is among the highest found in solids and nearly two orders of magnitude larger than the value measured along the c-axis (1-3). The recent rediscoveries of CNTs and SLG have expanded the applications of these graphitic nanomaterials for electronic devices, sensors, and light-weight composite materials, among others (4, 5). The performance and reliability of CNT and graphene devices are often closely related to the thermal properties of these nanoscale building blocks, similar to the situation in silicon nanoelectronic devices where localized heating has become a grand challenge (6). Hence, there have been a number of studies of thermal transport in these carbon nanostructures. Some of the studi...

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Section: Discussionsupporting

confidence: 85%

Phonon-interface scattering in multilayer graphene on an amorphous support

Sadeghi¹,

Jo²,

Shi

2013

Proc. Natl. Acad. Sci. U.S.A.

148

113

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“…The transmission coefficient exhibits a strong oscillatory behavior as a function of frequency with a decaying envelope. The similar frequency dependency was also observed in phonon transport across confined few-layer grapheme, 9 where the oscillatory behavior of transmission coefficient was shown to be the result of phonon interference arising from multiple scattering at the two interfaces.…”

Section: B Phonon Transport Across the Sijh-bnjal Interfacesupporting

confidence: 65%

“…It was found in numerous experiments and numerical simulations that the specular reflection and transmission of phonon waves at interfaces of nanostructured components may result in phonon interference effects which can be used for the modification of phonon dispersion and for controlling nanoscale heat transport. [1][2][3][4][5][6][7][8][9] To achieve strong phonon interference effects, the thickness of confined thin films should be smaller than the phonon mean free path (MFP) such that the phonons can travel ballistically between two interfaces of the thin film. Phonon MFPs of typical crystalline semiconductors such as Si, GaN, and graphite are on the order of tens of nanometers to micrometers.…”

Section: Introductionmentioning

confidence: 99%

Phonon interference in crystalline and amorphous confined nanoscopic films

Liang

Wilson

Keblinski

2017

Journal of Applied Physics

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Using molecular dynamics phonon wave packet simulations, we study phonon transmission across hexagonal (h)-BN and amorphous silica (a-SiO 2 ) nanoscopic thin films sandwiched by two crystalline leads. Due to the phonon interference effect, the frequency-dependent phonon transmission coefficient in the case of the crystalline film (Sijh-BNjAl heterostructure) exhibits a strongly oscillatory behavior. In the case of the amorphous film (Sija-SiO 2 jAl and Sija-SiO 2 jSi heterostructures), in spite of structural disorder, the phonon transmission coefficient also exhibits oscillatory behavior at low frequencies (up to $1.2 THz), with a period of oscillation consistent with the prediction from the two-beam interference equation. Above 1.2 THz, however, the phonon interference effect is greatly weakened by the diffuse scattering of higher-frequency phonons within an a-SiO 2 thin film and at the two interfaces confining the a-SiO 2 thin film. Published by AIP Publishing.

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“…Early works used kinetic theory to estimate that the average MFP along the c-axis is only a few nanometers at room temperature [25,26].…”

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confidence: 99%