Phonons and electron‐phonon coupling in graphene‐<i>h</i>‐BN heterostructures

Slotman, Guus J.; Wijs, G.A. de; Fasolino, A.; Katsnelson, M. I.

doi:10.1002/andp.201400155

Cited by 44 publications

(48 citation statements)

References 55 publications

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“…5(a) and 5(b), we show the calculated phonon dispersion and modes, respectively, when stacking monolayer graphene and an hBN monolayer. Consistent with previous calculations [35], the bands corresponding to in-plane modes are largely a superposition of the graphene and hBN phonon dispersions. The two acoustic flexural (ZA) modes of the individual layers hybridize into a gapped mode (ZO ) and a nongapped mode (ZA) with quadratic dispersion where atoms in graphene and hBN move out of phase and in phase in the z direction, respectively [ Fig.…”

Section: A Phonon Modes In Heterostructuressupporting

confidence: 89%

“…The gap of the original ZO mode increases from a value of 8.55 meV to a value of 9.66 meV, while an extra ZO mode with a gap of 5.78 meV emerges. Similar ZO gaps have been found in bilayer graphene (10 meV) [37] and on graphene on Cu/sapphire (6 meV) [38,39] and are a general feature of graphene on weakly interacting substrates [34,35,40]. The new ZO mode is exclusively localized in the hBN layers.…”

Section: A Phonon Modes In Heterostructuressupporting

confidence: 76%

“…Previous theoretical studies have mainly focused on vibrations in free-standing graphene [30,31] and graphene on bulk substrates [32][33][34] while the important case of interaction between graphene and few layer hBN encapsulation is less well described [35]. As we will argue below the decreased roughness in encapsulated graphene can be ascribed to (i) the splitting of modes localized in the graphene and hBN layers and (ii) the renormalization of the bands when increasing the number of layers.…”

Section: A Phonon Modes In Heterostructuresmentioning

confidence: 99%

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Suppression of intrinsic roughness in encapsulated graphene

et al. 2017

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Roughness in graphene is known to contribute to scattering effects which lower carrier mobility. Encapsulating graphene in hexagonal boron nitride (hBN) leads to a significant reduction in roughness and has become the de facto standard method for producing high-quality graphene devices. We have fabricated graphene samples encapsulated by hBN that are suspended over apertures in a substrate and used noncontact electron diffraction measurements in a transmission electron microscope to measure the roughness of encapsulated graphene inside such structures. We furthermore compare the roughness of these samples to suspended bare graphene and suspended graphene on hBN. The suspended heterostructures display a root mean square (rms) roughness down to 12 pm, considerably less than that previously reported for both suspended graphene and graphene on any substrate and identical within experimental error to the rms vibrational amplitudes of carbon atoms in bulk graphite. Our first-principles calculations of the phonon bands in graphene/hBN heterostructures show that the flexural acoustic phonon mode is localized predominantly in the hBN layer. Consequently, the flexural displacement of the atoms in the graphene layer is strongly suppressed when it is supported by hBN, and this effect increases when graphene is fully encapsulated.

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Section: A Phonon Modes In Heterostructuressupporting

confidence: 89%

Section: A Phonon Modes In Heterostructuressupporting

confidence: 76%

Section: A Phonon Modes In Heterostructuresmentioning

confidence: 99%

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Suppression of intrinsic roughness in encapsulated graphene

et al. 2017

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“…, with the size of the gap ω 0 reflecting the substrate interaction strength [18][19][20][40][41][42]. This introduces an effective cutoff q c ¼ ffiffiffiffiffiffiffiffiffiffi ffi ω 0 =b p below which flexural-phonon scattering is suppressed [8].…”

mentioning

confidence: 99%

Flexural-Phonon Scattering Induced by Electrostatic Gating in Graphene

2017

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Graphene has an extremely high carrier mobility partly due to its planar mirror symmetry inhibiting scattering by the highly occupied acoustic flexural phonons. Electrostatic gating of a graphene device can break the planar mirror symmetry yielding a coupling mechanism to the flexural phonons. We examine the effect of the gate-induced one-phonon scattering on the mobility for several gate geometries and dielectric environments using first-principles calculations based on density functional theory (DFT) and the Boltzmann equation. We demonstrate that this scattering mechanism can be a mobility-limiting factor, and show how the carrier density and temperature scaling of the mobility depends on the electrostatic environment. Our findings may explain the high deformation potential for in-plane acoustic phonons extracted from experiments and furthermore suggest a direct relation between device symmetry and resulting mobility.

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“…Different stacking arrangements in graphene/h‐BN vertical heterostructures are possible, resulting in different electronic and phononic properties . Heat dissipation from atomically thin 2D layers is limited by interfacial transport and makes them an ideal material system for the study of interfacial thermal transport.…”

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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Phonons and electron‐phonon coupling in graphene‐h‐BN heterostructures

Cited by 44 publications

References 55 publications

Suppression of intrinsic roughness in encapsulated graphene

Suppression of intrinsic roughness in encapsulated graphene

Flexural-Phonon Scattering Induced by Electrostatic Gating in Graphene

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

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