Phonon engineering in nanostructures: Controlling interfacial thermal resistance in multilayer-graphene/dielectric heterojunctions

Mao, Rui; Kong, Byoung Don; Kim, Ki Wook; Jayasekera, Thushari; Calzolari, Arrigo; Nardelli, Marco Buongiorno

doi:10.1063/1.4752437

Cited by 48 publications

(45 citation statements)

References 28 publications

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“…measured G between graphene and h -BN to be 7.4 MW/m 2 K51. Similarly, this result is still more than an order of magnitude smaller than the theoretically predicted value of 187 MW/m 2 K52, and is explained as a result of random lattice-mismatch and possible contaminations at the interface51. For MoS 2 , Taube et al .…”

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confidence: 78%

Thermal Conductance of the 2D MoS2/h-BN and graphene/h-BN Interfaces

Liu

Ong

et al. 2017

Sci Rep

105

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Two-dimensional (2D) materials and their corresponding van der Waals heterostructures have drawn tremendous interest due to their extraordinary electrical and optoelectronic properties. Insulating 2D hexagonal boron nitride (h-BN) with an atomically smooth surface has been widely used as a passivation layer to improve carrier transport for other 2D materials, especially for Transition Metal Dichalcogenides (TMDCs). However, heat flow at the interface between TMDCs and h-BN, which will play an important role in thermal management of various electronic and optoelectronic devices, is not yet understood. In this paper, for the first time, the interface thermal conductance (G) at the MoS2/h-BN interface is measured by Raman spectroscopy, and the room-temperature value is (17.0 ± 0.4) MW · m−2K−1. For comparison, G between graphene and h-BN is also measured, with a value of (52.2 ± 2.1) MW · m−2K−1. Non-equilibrium Green’s function (NEGF) calculations, from which the phonon transmission spectrum can be obtained, show that the lower G at the MoS2/h-BN interface is due to the weaker cross-plane transmission of phonon modes compared to graphene/h-BN. This study demonstrates that the MoS2/h-BN interface limits cross-plane heat dissipation, and thereby could impact the design and applications of 2D devices while considering critical thermal management.

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confidence: 78%

Thermal Conductance of the 2D MoS2/h-BN and graphene/h-BN Interfaces

Liu

Ong

et al. 2017

Sci Rep

105

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“…The g-hBN interface can be more transparent to heat carrying phonons because of the similar masses of carbon, boron, and nitrogen. 35 The curvature of the graphene sheet is an additional contributor to the interface thermal resistance in g-SiO 2 . 36 Annealing contributes to the graphene sheet conforming to the substrate and hBN being atomically flat means the graphene sheet in g-hBN has lower cumulative curvature than the graphene sheet in g-SiO 2 effectively decreasing interfacial resistance in g-hBN.…”

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confidence: 99%

Ultrafast relaxation of hot phonons in graphene-hBN heterostructures

et al. 2017

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Fast carrier cooling is important for high power graphene based devices. Strongly Coupled Optical Phonons (SCOPs) play a major role in the relaxation of photoexcited carriers in graphene. Heterostructures of graphene and hexagonal boron nitride (hBN) have shown exceptional mobility and high saturation current, which makes them ideal for applications, but the effect of the hBN substrate on carrier cooling mechanisms is not understood.We track the cooling of hot photo-excited carriers in graphene-hBN heterostructures using ultrafast pump-probe spectroscopy. We find that the carriers cool down four times faster in the case of graphene on hBN than on a silicon oxide substrate thus overcoming the hot phonon (HP) bottleneck that plagues cooling in graphene devices.Graphene heterostructures have garnered a lot of interest in the last decade 1 . Recently developed fabrication techniques have made it possible to engineer devices with better transport, optical and thermal properties 2,3 . Hexagonal boron nitride (hBN) is a layered material with a hexagonal lattice similar to graphene with a lattice constant that is about 1.8% larger 3 . It is an insulator with a wide band gap and high dielectric constant making it a good candidate as a substrate for graphene devices. Heterostructures of graphene and hBN show much higher mobility compared to those using SiO2 as a substrate 2-4 . This improvement is a result of the hBN substrate being free of charged impurities and displacing the graphene away from the impurities in the SiO2 substrate 4 .As electronic devices continue to scale down in size and push power capabilities, heat management has become a critical issue. Relaxation dynamics of photoexcited (PE) carriers has been studied extensively by many groups using variety of techniques such as photocurrent measurement, Raman time resolved Raman spectroscopy, transport measurements and ultrafast pump-probe spectroscopy 5-7 etc. Upon photoexcitation (with an ultrafast pulse for example), electrons and holes are excited, into a highly non-thermal system. This bath of carriers exchanges energy among themselves through coulombic interactions and thermalize into a hot (~1000's K) Fermi-Dirac population

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“…The TBC at graphene/h‐BN interfaces has been reported recently . Using first‐principles atomistic Green's function (AGF) simulations, Mao et al reported a room temperature (RT) TBC of 187 MW m −2 K −1 for a multilayer graphene/multilayer h‐BN structure. Zhang et al estimated the TBC at graphene nanoribbon/h‐BN bilayer structure to be 5 MW m −2 K −1 at RT using classical molecular dynamics (MD) simulations.…”

Section: Introductionmentioning

confidence: 99%

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

Brown

Bougher

Zhang

et al. 2019

Physica Status Solidi (a)

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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.

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Phonon engineering in nanostructures: Controlling interfacial thermal resistance in multilayer-graphene/dielectric heterojunctions

Cited by 48 publications

References 28 publications

Thermal Conductance of the 2D MoS2/h-BN and graphene/h-BN Interfaces

Thermal Conductance of the 2D MoS2/h-BN and graphene/h-BN Interfaces

Ultrafast relaxation of hot phonons in graphene-hBN heterostructures

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

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