Flexural resonance mechanism of thermal transport across graphene-SiO2 interfaces

Ong, Zhun-Yong; Qiu, Bo; Xu, Shaowen; Ruan, Xiulin; Pop, Eric

doi:10.1063/1.5020705

Cited by 31 publications

(30 citation statements)

References 49 publications

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“…We explain these trends using Landauer’s formalism (see section S9 for details), wherein the TBC across the interface is proportional to the product of the phonon density of states (PDOS) overlap, the transmission coefficient, and d f /d T , where f is Bose-Einstein distribution. Here, we consider the PDOS for flexural out-of-plane (ZA) phonons, which have been shown to dominate cross-plane heat conduction in 2D materials ( 32 ). For the SiO 2 substrate, we consider the typical longitudinal acoustic (LA) and transverse acoustic (TA) phonon branches.…”

Section: Resultsmentioning

confidence: 99%

Ultrahigh thermal isolation across heterogeneously layered two-dimensional materials

et al. 2019

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Heterogeneous integration of nanomaterials has enabled advanced electronics and photonics applications. However, similar progress has been challenging for thermal applications, in part due to shorter wavelengths of heat carriers (phonons) compared to electrons and photons. Here, we demonstrate unusually high thermal isolation across ultrathin heterostructures, achieved by layering atomically thin two-dimensional (2D) materials. We realize artificial stacks of monolayer graphene, MoS2, and WSe2 with thermal resistance greater than 100 times thicker SiO2 and effective thermal conductivity lower than air at room temperature. Using Raman thermometry, we simultaneously identify the thermal resistance between any 2D monolayers in the stack. Ultrahigh thermal isolation is achieved through the mismatch in mass density and phonon density of states between the 2D layers. These thermal metamaterials are an example in the emerging field of phononics and could find applications where ultrathin thermal insulation is desired, in thermal energy harvesting, or for routing heat in ultracompact geometries.

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Section: Resultsmentioning

confidence: 99%

Ultrahigh thermal isolation across heterogeneously layered two-dimensional materials

et al. 2019

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“…To understand the low conductances associated with interfaces comprised of 2D materials, there have been considerable advances both from atomistic simulations as well as analytical and theoretical frameworks . One of the main findings from the MD simulations is that the conductance across the dimensionally mismatched graphene and substrate can be ascribed to the coupling between flexural acoustic phonons of graphene and the longitudinal phonons in the substrate .…”

Section: Thermal Boundary Conductance Across Interfaces Composed Of 2mentioning

confidence: 99%

A Review of Experimental and Computational Advances in Thermal Boundary Conductance and Nanoscale Thermal Transport across Solid Interfaces

Giri

Hopkins

2019

Adv Funct Materials

207

152

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Interfacial thermal resistance is the primary impediment to heat flow in materials and devices as characteristic lengths become comparable to the mean‐free paths of the energy carriers. This thermal boundary conductance across solid interfaces at the nanoscale can affect a plethora of applications. The recent experimental and computational advances that have led to significant atomistic insights into the nanoscopic thermal transport mechanisms at interfaces between various types of materials are summarized. The authors focus on discussions of works that have pushed the limits to interfacial heat transfer and drastically increased the understanding of thermal boundary conductance on the atomic and nanometer scales near solid/solid interfaces. Specifically, the role of localized interfacial modes on the energy conversion processes occurring at interfaces is emphasized in this review. The authors also focus on experiments and computational works that have challenged the traditionally used phonon gas models in interpreting the physical mechanisms driving interfacial energy transport. Finally, the authors discuss the future directions and avenues of research that can further the knowledge of heat transfer across systems with broken symmetries.

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“…We note that this transfer process is harmonic and conserves energy but it does not conserve momentum due to the mismatch between the phase spaces and the presence of atomic-scale , calculated from firstprinciples using density functional perturbation theory. The gapped ZA (g-ZA) branch of each 2D layer is highlighted in red and is the primary contributor of thermal transport across the interface [36].…”

Section: D-3d Thermal Boundary Conductancementioning

confidence: 99%

Quantifying thermal boundary conductance of 2D–3D interfaces

Foss

Akšamija

2019

2D Mater.

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Heat dissipation in next-generation electronics based on two-dimensional (2D) materials is a critical issue in their development and implementation. A potential bottleneck for heat removal in 2D-based devices is the thermal pathway from the 2D layer into its supporting substrate. The choice of substrate, its composition and structure, can strongly impact the thermal boundary conductance (TBC). Here we investigate the temperature-dependent TBC of 42 interfaces formed between a group of six 2D materials and seven crystalline and amorphous substrates. We use first-principles density functional perturbation theory to calculate the full phonon dispersion of the 2D layers and substrates and then input them into our model for phonon transport across the 2D-3D interface. Our results show that the TBC depends on the overlap between the vibrational frequencies and can be varied by nearly two orders of magnitude, from as low as ∼0.6 MW • m −2 • K −1 (h-BN on diamond) to ∼40 MW • m −2 • K −1 (h-BN on SiO 2), for the same 2D layer by changing the substrate material. We find that amorphous materials significantly boost the TBC relative to their crystalline counterparts, assuming the two interfaces have the same adhesion, owing to the low-frequency Boson peak feature in their vibrational density of states (vDOS). For crystalline substrates, we further correlate constituent material properties with the calculated TBCs and find that the TBC strongly depends on a combination of the speed of sound, Debye temperature, and density of the substrate as well as the bandwidth of the flexural branch in the 2D material. We conclude that softer substrates with sharp low-frequency features in their vDOS, such as amorphous materials, polymers, and nanoparticles, could have higher TBC, leading to a trade-off between TBC and the thermal conductivity of the substrate.

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Flexural resonance mechanism of thermal transport across graphene-SiO2 interfaces

Cited by 31 publications

References 49 publications

Ultrahigh thermal isolation across heterogeneously layered two-dimensional materials

Ultrahigh thermal isolation across heterogeneously layered two-dimensional materials

A Review of Experimental and Computational Advances in Thermal Boundary Conductance and Nanoscale Thermal Transport across Solid Interfaces

Quantifying thermal boundary conductance of 2D–3D interfaces

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