Scaling of High-Field Transport and Localized Heating in Graphene Transistors

Bae, Myung‐Ho; Islam, Sharnali; Dorgan, Vincent E.; Pop, Eric

doi:10.1021/nn202239y

Cited by 81 publications

(110 citation statements)

References 32 publications

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“…Thus, high thermal conductivity could superficially suggest very good heat sinking and low temperature rise during device operation. However, under high-field and high-temperature (i.e., typical circuit) operating conditions, significant dissipation and temperature rise can nevertheless occur in graphene devices, 38,81 as shown in Figure 5.…”

Section: Devices and Interconnectsmentioning

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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Section: Devices and Interconnectsmentioning

confidence: 99%

Thermal properties of graphene: Fundamentals and applications

2012

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“…[9][10][11][12][13] Nevertheless, several of graphene's remarkable properties do make it attractive for the realization of an infrared incandescent source. For example, it is able to sustain extremely large current densities: 10 7 A/cm 2 in micron sized wires fabricated from graphene grown by chemical vapor deposition (CVD), 8 compared to values of $100 A/cm 2 in a conventional tungsten filament light bulb.…”

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Boron nitride encapsulated graphene infrared emitters

Barnard

Zossimova

Mahlmeister

et al. 2016

Applied Physics Letters

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The spatial and spectral characteristics of mid-infrared thermal emission from devices containing a large area multilayer graphene layer, encapsulated using hexagonal boron nitride, have been investigated. The devices were run continuously in air for over 1000 h, with the emission spectrum covering the absorption bands of many important gases. An approximate solution to the heat equation was used to simulate the measured emission profile across the devices yielding an estimated value of the characteristic length, which defines the exponential rise/fall of the temperature profile across the device, of 40 μm. This is much larger than values obtained in smaller exfoliated graphene devices and reflects the device geometry, and the increase in lateral heat conduction within the devices due to the multilayer graphene and boron nitride layers.

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“…Although this makes it attractive for potential use as an incandescent source, 3 thermal emission from graphene has primarily been used over the last few years as a means of probing the electronic structure of graphene transistor devices under bias. [4][5][6][7] However, there is a continuing need for the development of new infrared sources to enable low cost, intrinsically safe, portable infrared gas sensors for applications such as mine safety. Most existing infrared (IR) sensors use conventional incandescent sources which have several shortcomings including slow response time, limited wavelength range (due to the glass envelope of the source), limited lifetimes due to the fragility of the source, relatively high power consumption, and a requirement for explosion proof housings to prevent the source from igniting flammable gases that may be present.…”

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“…devices, [3][4][5][6][7] and also in large area CVD devices, 8 where the thermal emission is dominated by Joule heating governed by the charge distribution along the channel. In this case given the symmetrical nature and scaling of the emission we estimate the hotspot to be approximately half-way between the source and the drain contacts.…”

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Prospective for graphene based thermal mid-infrared light emitting devices

et al. 2014

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We have investigated the spatial and spectral characteristics of mid-infrared thermal emission from large area Chemical Vapor Deposition (CVD) graphene, transferred onto SiO2/Si, and show that the emission is broadly that of a grey-body emitter, with emissivity values of approximately 2% and 6% for mono- and multilayer graphene. For the currents used, which could be sustained for over one hundred hours, the emission peaked at a wavelength of around 4 μm and covered the characteristic absorption of many important gases. A measurable modulation of thermal emission was obtained even when the drive current was modulated at frequencies up to 100 kHz.

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Scaling of High-Field Transport and Localized Heating in Graphene Transistors

Cited by 81 publications

References 32 publications

Thermal properties of graphene: Fundamentals and applications

Thermal properties of graphene: Fundamentals and applications

Boron nitride encapsulated graphene infrared emitters

Prospective for graphene based thermal mid-infrared light emitting devices

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