Phonon scattering at a rough interface between two fcc lattices

Zhao, Hong Jian; Freund, Jonathan B.

doi:10.1063/1.3054383

Cited by 69 publications

(66 citation statements)

References 16 publications

(19 reference statements)

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“…For single Si/Ge interfaces, effects of strain [23], lattice mismatch [24], and interface roughness [25,26] on phonon transmission have been investigated. Green's function study on Si/Ge superlattices, however, is scarce.…”

Section: Introductionmentioning

confidence: 99%

Green's function studies of phonon transport across Si/Ge superlattices

2014

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Understanding and manipulating coherent phonon transport in solids is of interest both for enhancing the fundamental understanding of thermal transport as well as for many practical applications, including thermoelectrics. In this study, we investigate phonon transmission across Si/Ge superlattices using the Green's function method with first-principles force constants derived from ab initio density functional theory. By keeping the period thickness fixed while changing the number of periods, we show that interface roughness partially destroys coherent phonon transport, especially at high temperatures. The competition between the low-frequency coherent modes and high-frequency incoherent modes leads to an optimum period length for minimum thermal conductivity. To destroy coherence of the low-frequency modes, scattering length scale on the order of period length is required. This finding is useful to guide the design of superlattices to reach even lower thermal conductivity.

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Section: Introductionmentioning

confidence: 99%

Green's function studies of phonon transport across Si/Ge superlattices

2014

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“…In particular, they studied the dependence of junction thermal conductance on junction length using both SBM calculations and NEMD simulations. 33 Tian et al 34 studied Si-Ge superlattice junctions using a harmonic lattice-based technique, 35,36 where they found that the introduction of disorder at interfaces destroyed coherent transport of phonons, particularly those with high frequencies.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductance of superlattice junctions

McGaughey

2015

AIP Advances

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We use molecular dynamics simulations and the lattice-based scattering boundary method to compute the thermal conductance of finite-length Lennard-Jones superlattice junctions confined by bulk crystalline leads. The superlattice junction thermal conductance depends on the properties of the leads. For junctions with a superlattice period of four atomic monolayers at temperatures between 5 and 20 K, those with mass-mismatched leads have a greater thermal conductance than those with mass-matched leads. We attribute this lead effect to interference between and the ballistic transport of emergent junction vibrational modes. The lead effect diminishes when the temperature is increased, when the superlattice period is increased, and when interfacial disorder is introduced, but is reversed in the harmonic limit. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

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“…In particular, the frequency-dependent phonon transmission across a variety of material interfaces has been studied using the AGF approach, such as the interface in low dimensional atomic chains, 26 strained Si/Ge interface, 27 metal/graphene nanoribbon (GNR) interface, 28 rough interface between two face-centered cubic (FCC) crystals, 29 and more recently across confined material interfaces. 30 However, all the past AGF-based studies on phonon transmission across interfaces [27][28][29][30][31][32] focused on lattice-matched material interfaces, where the inter-atomic distance of one material is usually adjusted to match that in the other material in the directions parallel to the interface to simplify the calculations. For example, Si (or Ge) is strained to have the same lattice constant as Ge (or Si) along the interface plane to study phonon transmission across Si/Ge interface while the inter-atomic distance in the direction perpendicular to the interface is adjusted according to the Poisson's ratio in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. 29, two FCC crystals with mass ratio and force constant ratio inherited from Si and Ge are used for the study of phonon transmission across rough interfaces and the lattice constants of the two crystals are adjusted to match each other. In the latticematched systems, perfect atomic bonds similar to the ones in their constituent materials are formed at the interface, with no bond breaking or reconstruction, since the inter-atomic distance is the same for both materials at the interface.…”

Section: Introductionmentioning

confidence: 99%

Effect of lattice mismatch on phonon transmission and interface thermal conductance across dissimilar material interfaces

Yang

2012

Phys. Rev. B

135

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When phonons transport across a material interface, they experience reflection, transmission and mode conversion, which results in a local temperature jump at interface and thus dramatically changes the thermal conductivity of nanostructured materials. Phonon transmission across lattice-matched interfaces has been studied extensively in recent years with the atomistic Green's function (AGF) approach, which usually uses one unit cell to represent the cross-section along the interface. However, modeling phonon transmission across realistic material interfaces is much more challenging because realistic interfaces are usually latticemismatched ones with atomic reconstruction, defects, and species mixing, which demands a larger cross-sectional area for the AGF simulation. In this paper, an integrated molecular dynamics (MD) and AGF approach is developed to study the phonon transmission across latticemismatched interfaces. MD simulation is used to simulate atomic reconstruction close to the 1 Email: Ronggui.Yang@Colorado.Edu interface. The recursive AGF approach is then employed for the first time to calculate frequencydependent phonon transmission across lattice-mismatched interfaces with defects and species mixing, which addresses the numerical challenge in calculating phonon transmission for a relatively large cross-sectional area with reduced computational cost. The study of the relaxed interface formed from two semi-infinite bulk materials shows that lattice mismatch increases the lattice disorder and decreases the adhesion energy, which in turn lowers phonon transmission and reduces the interface thermal conductance across lattice-mismatched interfaces. Low-frequency phonons can be significantly scattered by increasing the defect size across the interface while high frequency phonons can be scattered almost completely (phonon transmission <0.1) across an alloyed layer as thin as 2.27 nm. The effect of lattice-mismatch on phonon transmission becomes smaller for interfaces with defects and species mixing. The effect of annealing temperature on the Si/Ge interface thermal conductance was studied. A significant reduction of the Si/Ge interface thermal conductance was observed for a lattice-mismatched interface when annealed at high temperature, which agrees well with the available experimental data in literature.

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Phonon scattering at a rough interface between two fcc lattices

Cited by 69 publications

References 16 publications

Green's function studies of phonon transport across Si/Ge superlattices

Green's function studies of phonon transport across Si/Ge superlattices

Thermal conductance of superlattice junctions

Effect of lattice mismatch on phonon transmission and interface thermal conductance across dissimilar material interfaces

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