We report the measurement of the thermal conductivity of a suspended single-layer graphene. The room temperature values of the thermal conductivity in the range ∼(4.84 ± 0.44) × 103 to (5.30 ± 0.48) × 103 W/mK were extracted for a single-layer graphene from the dependence of the Raman G peak frequency on the excitation laser power and independently measured G peak temperature coefficient. The extremely high value of the thermal conductivity suggests that graphene can outperform carbon nanotubes in heat conduction. The superb thermal conduction property of graphene is beneficial for the proposed electronic applications and establishes graphene as an excellent material for thermal management.

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Superior Thermal Conductivity of Single-Layer Graphene

There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

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Graphene and Graphene Oxide: Synthesis, Properties, and Applications

We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.

Band parameters for III–V compound semiconductors and their alloys

Recent years have seen a rapid growth of interest by the scientific and engineering communities in the thermal properties of materials. Heat removal has become a crucial issue for continuing progress in the electronic industry, and thermal conduction in low-dimensional structures has revealed truly intriguing features. Carbon allotropes and their derivatives occupy a unique place in terms of their ability to conduct heat. The room-temperature thermal conductivity of carbon materials span an extraordinary large range--of over five orders of magnitude--from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. Here, I review the thermal properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. Special attention is given to the unusual size dependence of heat conduction in two-dimensional crystals and, specifically, in graphene. I also describe the prospects of applications of graphene and carbon materials for thermal management of electronics.

Thermal properties of graphene and nanostructured carbon materials

Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...

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Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Comment on ``Use of quantum well superlattices to obtain high figure of merit from nonconventional thermoelectric materials'' [Appl. Phys. Lett. 63, 3230 (1993)]

Electronic Raman scattering (ERS) measurements of photoexcited holes have been performed on $\mathrm{GaAs}/{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ multiple quantum wells grown in the [111] $b$ and [100] directions These measurements indicate that the heavy- and light-hole masses along the [111] direction are $075{m}_{0}$ and $0082{m}_{0}$, respectively These values, compared with the heavy- and light-hole masses in the [100] direction ($034{m}_{0}$ and $0094{m}_{0}$ respectively), reveal the highly anisotropic nature of the valence band in GaAs We propose a new set of Luttinger parameters that describes this anisotropy

Luttinger parameters for GaAs determined from the intersubband transitions in GaAs/Al x Ga 1-x As multiple quantum wells

The lattice thermal conductivity of (Bi${}_{1\ensuremath{-}x}$Sb${}_{x}$)${}_{2}$Te${}_{3}$ alloys, with and without spherical nanoparticle inclusions, has been computed using the Boltzmann transport equation with classical interatomic potentials within the relaxation time approximation. The experimental thermal conductivity of the pure alloys is fairly well reproduced as a function of concentration. We establish upper and lower limits for the thermal conductivities that could be obtained via seamlessly embedded spherical nanoparticles as a function of their size, density, and volume fraction. Large reductions in thermal conductivities (40--50$%$) can only be achieved with small nanoparticles with diameters below 10 nm.

Lattice thermal conductivity of (Bi 1 − x Sb x ) 2 Te 3 alloys with embedded nanoparticles

The effects of anisotropy of the valence-band structure and of the mixing of the heavy and light holes on the Landau levels of the hole inversion layer in a normal magnetic field are studied Some of the crossings of the Landau levels which occur when anisotropy is neglected are removed when it is included While the measured multiple cyclotron-resonance frequencies are explained qualitatively by our calculation, there is quantitative disagreement

Holes at GaAs-AlxGa1-xAs heterojunctions in magnetic fields

Author(s): Romano, Giuseppe; Esfarjani, Keivan; Strubbe, David A; Broido, David; Kolpak, Alexie M | Abstract: Nanostructured materials exhibit low thermal conductivity because of the additional scattering due to phonon-boundary interactions. As these interactions are highly sensitive to the mean free path (MFP) of a given phonon mode, MFP distributions in nanostructures can be dramatically distorted relative to bulk. Here we calculate the MFP distribution in periodic nanoporous Si for different temperatures, using the recently developed MFP-dependent Boltzmann Transport Equation. After analyzing the relative contribution of each phonon branch to thermal transport in nanoporous Si, we find that at room temperature optical phonons contribute 18 % to heat transport, compared to 5% in bulk Si. Interestingly, we observe a steady thermal conductivity in the nanoporous materials over a temperature range 200 K l T l 300 K, which we attribute to the ballistic transport of acoustic phonons with long intrinsic MFP. These results, which are also consistent with a recent experimental study, shed light on the origin of the reduction of thermal conductivity in nanostructured materials, and could contribute to multiscale heat transport engineering, in which the bulk material and geometry are optimized concurrently.

David Broido

Papers

Comment on ``Use of quantum well superlattices to obtain high figure of merit from nonconventional thermoelectric materials'' [Appl. Phys. Lett. 63, 3230 (1993)]

Luttinger parameters for GaAs determined from the intersubband transitions in GaAs/Al x Ga 1-x As multiple quantum wells

Lattice thermal conductivity of (Bi 1 − x Sb x ) 2 Te 3 alloys with embedded nanoparticles

Holes at GaAs-AlxGa1-xAs heterojunctions in magnetic fields

Temperature-dependent thermal conductivity in silicon nanostructured materials studied by the Boltzmann transport equation