Thermal transport in graphene junctions and quantum dots

Xu, Yong; Chen, Xiaobin; Wang, Jian‐Sheng; Gu, Bing-Lin; Duan, Wenhui

doi:10.1103/physrevb.81.195425

Cited by 103 publications

(76 citation statements)

References 44 publications

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“…Of course, all realistic devices are of finite length, and the study of size effects is important for practical purposes. 50 For completeness, we mention here other related studies that have recently been reported. A number of studies of electron and/or phonon transport properties of regular defects in ribbons are available (see, e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric properties of finite graphene antidot lattices

et al. 2011

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We present calculations of the electronic and thermal transport properties of graphene antidot lattices with a finite length along the transport direction. The calculations are based on a single orbital tight-binding model and the Brenner potential. We show that both electronic and thermal transport properties converge fast toward the bulk limit with increasing length of the lattice: only a few repetitions (~6) of the fundamental unit cell are required to recover the electronic band gap of the infinite lattice as a transport gap for the finite lattice. We investigate how different antidot shapes and sizes affect the thermoelectric properties. The resulting thermoelectric figure of merit, ZT, can exceed 0.25, and it is highly sensitive to the atomic arrangement of the antidot edges. Specifically, hexagonal holes with pure zigzag edges lead to an order-of-magnitude smaller ZT as compared to pure armchair edges. We explain this behavior as a consequence of the localization of states, which predominantly occurs for zigzag edges, and of an increased splitting of the electronic minibands, which reduces the power factor.Comment: 12 pages, 13 figures. Submitted to Phys. Rev.

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Section: Introductionmentioning

confidence: 99%

Thermoelectric properties of finite graphene antidot lattices

et al. 2011

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“…49 Existing methods for modeling thermal transport in graphene and GNRs include atomistic techniques such as molecular dynamics (MD), 16,25,[50][51][52][53][54][55][56] non-equilibrium Green's functions (NEGF), [57][58][59][60] and…”

Section: Thermal Modeling Of Graphenementioning

confidence: 99%

Thermal properties of graphene: Fundamentals and applications

2012

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this preprint draft may differ slightly from the final published versionGraphene is a two-dimensional (2D) material with over 100-fold anisotropy of heat flow between the in-plane and out-of-plane directions. High inplane thermal conductivity is due to covalent sp 2 bonding between carbon atoms, whereas out-of-plane heat flow is limited by weak van der Waals coupling.Herein, we review the thermal properties of graphene, including its specific heat and thermal conductivity (from diffusive to ballistic limits) and the influence of substrates, defects, and other atomic modifications. We also highlight practical applications in which the thermal properties of graphene play a role. For instance, graphene transistors and interconnects benefit from the high in-plane thermal conductivity, up to a certain channel length. However, weak thermal coupling with substrates implies that interfaces and contacts remain significant dissipation bottlenecks. Heat flow in graphene or graphene composites could also be tunable through a variety of means, including phonon scattering by substrates, edges or interfaces. Ultimately, the unusual thermal properties of graphene stem from its 2D nature, forming a rich playground for new discoveries of heat flow physics and potentially leading to novel thermal management applications.MRS Bull. 37, 1273Bull. 37, (2012 Pop/Varshney/Roy 2 IntroductionGraphene is a two-dimensional (2D) material, formed of a lattice of hexagonally arranged carbon atoms. Graphene is typically referred to as a single layer of graphite, although common references also exist to bilayer or trilayer graphene. (See the introductory article in this issue.) Most thermal properties of graphene are derived from those of graphite and bear the imprint of the highly anisotropic nature of this crystal. 1 For instance, the in-plane covalent sp 2 bonds between adjacent carbon atoms are among the strongest in nature (slightly stronger than the sp 3 bonds in diamond), with a bonding energy of approximately 2 5.9 eV. By contrast, the adjacent graphene planes within a graphite crystal are linked by weak van der Waals interactions 2 (~50 meV) with a spacing 3 of h ≈ 3.35Å. Figure 1a displays the typical ABAB (also known as Bernal) stacking of graphene sheets within a graphite crystal.The strong and anisotropic bonding and the low mass of the carbon atomsgive graphene and related materials unique thermal properties. In this article we survey these unusual properties and their connection with the character of the underlying lattice vibrations. We examine both specific heat and thermal conductivity of graphene and related materials, and the conditions for achieving ballistic, scattering-free heat flow. We also investigate the role of atomistic lattice modifications and defects in tuning the thermal properties of graphene. Finally we explore the role of heat conduction in potential device applications and the possibility of architectures that allow control over the thermal anisotropy. Phonon dispersion of grapheneTo understand the thermal ...

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“…TE quantities of electrons and phonons can be described by their transmission functions [35][36][37][38][39][40][41][42] . When the electronic transmission function T (E) is a smooth function and the temperature is low, the Sommerfield expansion of S gives…”

Section: Size Dependent Thermoelectric Properties In Topological Insumentioning

confidence: 99%

Thermoelectric effects and topological insulators

2016

Chinese Phys. B

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The recent discovery of topological insulator (TI) offers new opportunities for the development of thermoelectrics, because many TIs (like Bi2Te3) are excellent thermoelectric (TE) materials. In this review, we will first describe the general TE properties of TIs and show that the coexistence of the bulk and boundary states in TIs introduces unusual TE properties, including strong size effects and anomalous Seebeck effect.Importantly, the TE figure of merit zT of TIs is no longer an intrinsic property, but depends strongly on the geometric size. The geometric parameters of two-dimensional TIs can be tuned to enhance zT to be significantly greater than 1. Then a few proof-of-principle experiments on three-dimensional TIs will be discussed, which observed unconventional TE phenomena that are closely related to the topological nature of the materials. However, current experiments indicate that the metallic surface states, if their advantage of high mobility is not fully utilized, would be detrimental to TE performance. Finally we provide an outlook for future work on topological materials, which offers great possibilities to discover exotic TE effects and may lead to significant breakthroughs in improving zT .

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Thermal transport in graphene junctions and quantum dots

Cited by 103 publications

References 44 publications

Thermoelectric properties of finite graphene antidot lattices

Thermoelectric properties of finite graphene antidot lattices

Thermal properties of graphene: Fundamentals and applications

Thermoelectric effects and topological insulators

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