Coherent and incoherent phonon thermal transport in isotopically modified graphene superlattices

Mu, Xin; Zhang, Teng; Go, David B.; Luo, Tengfei

doi:10.1016/j.carbon.2014.11.028

Cited by 70 publications

(68 citation statements)

References 64 publications

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“…In addition, recent advances in materials science have allowed to engineer the density of states and the group velocity of thermal phonons via interference phenomena in superlattices [24,25] (SLs). Both experimental [26][27][28][29][30] and numerical [31][32][33][34][35][36][37][38][39][40][41][42][43] works stated the importance of coherence on the thermal properties of SLs, as both a wave and a particle description of phonons are necessary to explain most of the results. So far, no clear theoretical framework has allowed to establish quantitatively to what extent phonon modes transit * yann.chalopin@cnrs.fr from a pure plane-wave behavior toward a diffusive pointlike particle.…”

Section: Introductionmentioning

confidence: 99%

Distinguishing between spatial coherence and temporal coherence of phonons

Latour

Chalopin

2017

Phys. Rev. B

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Coherent phonon transport is regarded as a promising strategy for controlling thermal properties in solids using the wave nature of phonons. However, no clear distinction between the spatial and temporal phonon coherence has been accounted for and a formalism that quantifies these two effects is still to be found. In this work, we propose a statistical approach for calculating the spatial and temporal coherence spectra using molecular dynamics simulations. We provide a microscopic assessment of these properties and we theoretically demonstrate that, while temporal and spatial coherence can be analytically related under specific conditions, they represent two characteristic lengths that set apart different physical effects. The former is associated with the phonon mean free path while the latter can be regarded as a measure of localization, representing the spatial extension of phonon wave packets. This provides a framework to engineer heat conduction in solids by quantitatively revealing the wave/particle nature of the vibrational modes.

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Section: Introductionmentioning

confidence: 99%

Distinguishing between spatial coherence and temporal coherence of phonons

Latour

Chalopin

2017

Phys. Rev. B

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“…Quantum-well superlattice structures composed of a periodic arrangement of nanolayers from two semiconductors with significant band-gap and mass mismatch, usually combine high thermoelectric power with low thermal conductivity at the nanoscale; two properties of primary interest for thermoelectric applications [1,2]. Evidence for a minimum of thermal conductivity when the superlattice period decreases below a critical thickness is well established [3][4][5][6][7][8]. Considerable research effort has been devoted to understanding the fundamental regime transition from incoherent to coherent in order to control thermal conductivity in superlattices.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic nanotwin effect on thermal boundary conductance in bulk and single-nanowire twinning superlattices

2016

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Coherent twin boundaries form periodic lamellar twinning in a wide variety of semiconductor nanowires, and are often viewed as near-perfect interfaces with reduced phonon and electron scattering behaviors. Such unique characteristics are of practical interest for high-performance thermoelectrics and optoelectronics; however, insufficient understanding of twin-size effects on thermal boundary resistance poses significant limitations for potential applications. Here, using atomistic simulations and ab-initio calculations, we report direct computational observations showing a crossover from diffuse interface scattering to superlattice-like behavior for thermal transport across nanoscale twin boundaries present in prototypical bulk and nanowire Si examples.Intrinsic interface scattering is identified for twin periods ≥ 22.6 nm, but also vanishes below this size to be replaced by ultrahigh Kapitza thermal conductances. Detailed analysis of vibrational modes shows that modeling twin boundaries as atomically-thin 6H-Si layers, rather than phonon scattering interfaces, provides an accurate description of effective cross-plane and in-plane thermal conductivities in twinning superlattices, as a function of the twin period thickness.3

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“…The armchair and zigzag directions in graphene monolayer are along the x and y directions, respectively. In addition, 13 C can be selected as the isotopic doping atoms [26], which substitutes the removing atoms in SC fractal structures, and the other atoms can be modeled by natural atoms ( 12 C).…”

Section: Model and Simulation Details 21 Modelmentioning

confidence: 99%

Atomistic simulations of phonon behaviors in isotopically doped graphene with Sierpinski carpet fractal structure

Han

Fan

Wang

et al. 2020

Mater. Res. Express

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Two-dimensional (2D) graphene monolayer has been attached importance because of the fantastic physical properties. In this work, we conduct the atomistic simulations to evaluate the phonon behaviors in isotopically doped graphene with Sierpinski Carpet (SC) fractal structure. The thermal conductivities (k) with different fractal numbers are calculated by molecular dynamics simulation. The relationship between the k and the fractal number from 0 to 8 shows a first decreasing and then stable trend. The maximum reduction ratio of the k in SC fractal structures is 52.37%. Afterwards, we utilize the molecular dynamics simulation, phonon wave packet simulation and lattice dynamics simulation to investigate the phonon density of states (PDOS), energy transmission coefficient (ETC), phonon group velocity and participation ratio (PR) in SC fractal structures. In SC fractal structures, the PDOS increases in the low frequency region and the G-band will soften with the enhanced fractal number. We also observe that the isotopic doping atoms can lead to continuous reflected waves in SC fractal structure regions. Moreover, phonon modes in SC fractal structures possess the lower ETCs, phonon group velocities and PRs in comparison with the pristine graphene monolayer. Therefore, we attribute the lower k in SC fractal structures to the stronger phonon-impurity scattering and the increasing localized phonon modes.

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Coherent and incoherent phonon thermal transport in isotopically modified graphene superlattices

Cited by 70 publications

References 64 publications

Distinguishing between spatial coherence and temporal coherence of phonons

Distinguishing between spatial coherence and temporal coherence of phonons

Intrinsic nanotwin effect on thermal boundary conductance in bulk and single-nanowire twinning superlattices

Atomistic simulations of phonon behaviors in isotopically doped graphene with Sierpinski carpet fractal structure

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