Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fast flowing heat in layered material heterostructures

18.12.2017

Graphene Flagship scientists, led by researchers at ICFO - The Institute of Photonic Sciences in Barcelona, Spain, have detected graphene's out-of-plane heat transfer in van der Waals heterostructures. In their paper published in Nature Nanotechnology they follow this process in real-time. This phenomenon has many implications for optoelectronic devices.

Nanoscale heat flow plays a crucial role in many modern electronic and optoelectronic applications, such as thermal management, photodetection, thermoelectrics and data communication. Layered materials are very promising for many of these applications.


Schematic representation of the highly efficient out-of-plane heat transfer from graphene hot electrons (yellow glow), created by optical excitation (red beam), to hyperbolic phonon-polaritons in hBN (wave lines).

Credit: ICFO

Heterostructures consisting of different layered materials stacked one on top of the other open an even wider range of opportunities. These stacks can consist of materials with different physical properties, while the interfaces between them are ultraclean and atomically sharp.

Graphene has a large in-plane thermal conductivity, making it ideal for thermal management of nanoscale devices. The understanding of the out-of-plane heat transfer in heterostructures can help to improve the performance of graphene based electronic and optoelectronic devices.

This was a collaborative research effort within the Graphene Flagship, lead by ICREA Professor Frank Koppens from ICFO - The Institute of Photonic Sciences in Barcelona, Spain and also comprising researchers from Flagship partners in The Netherlands (Radboud University), Italy (Istituto Italiano di Tecnologia - IIT, Consiglio Nazionale delle Ricerche - CNR), Germany (RWTH Aachen University, Max Planck Institute for Polymer Research) and the United Kingdom (The University of Manchester and The University of Cambridge).

They observed and followed, in real-time, the way in which heat transport occurs in stacks consisting of graphene encapsulated by the dielectric layered material, hexagonal boron nitride (hBN).

'Apart from the scientific interest, these findings are also very important for the development of ultra-fast photodetectors.' Said ICREA Professor Frank Koppens.

The team identified an interesting effect: rather than staying within the graphene sheet, the heat flows to the surrounding hBN. This occurs on an ultrafast timescale of picoseconds (one millionth of a millionth of a second), and is therefore dominant over competing (in-plane) heat transfer processes.

This was found to rely on two interesting phenomena: hot electrons in graphene and hyperbolic phonons in hBN. Graphene makes hot electrons by transferring incident light into electrical heat and it is these hot electrons that interact with the adjacent hBN layer and enable the out-of-plane heat transfer. The process for this involves the coupling of the hot electrons to hyperbolic phonon-polaritons in the hBN sheets which then propagate within the hBN as light does in an optical fiber, but in this case for infrared wavelengths and at the nanometer scale. It turns out that these hyperbolic modes are very efficient at carrying heat away.

'To study these heat transport phenomena we fabricated a graphene-based photodetector and examined the photoresponse as a function of time delay between two incident light pulses of femtosecond duration. This allowed us to obtain the dynamics of the photoresponse, which indicated carrier cooling on a picosecond timescale. The cooling dynamics exhibited a distinct dependence on graphene carrier density, substrate temperature, hot electron temperature, and - strikingly - hBN sheet thickness.

All observations are in quantitative agreement with out-of-plane cooling to hBN hyperbolic phonons as confirmed by theoretical calculations. Based on this understanding of heat transfer, follow-up studies are now aimed at controlling heat transfer.' said Klaas-Jan Tielrooij from ICFO who is the lead author on the paper.

The results of this work have implications for many applications based on hBN-encapsulated graphene, sometimes referred to as the next generation graphene platform owing to its superior electrical properties. In particular, it will provide direction to optoelectronic device design, where these heat flow processes can be thoroughly exploited.

Professor Andrea C. Ferrari, Science and Technology Officer of the Graphene Flagship, and Chair of its Management Panel, added 'the combination of graphene and BN is at the moment the most promising to develop future optoelectronic devices, such as modulators and detectors. This work will have implications to implement the Flagship roadmap translating the potential of graphene and related materials for applications in the future 5G communications and the Internet of Things.'

###

REFERENCE

Out-of-plane heat transfer in van der Waals stacks through electron-hyperbolic phonon coupling. K. J. Tielrooij, N. C. H. Hesp, A. Principi, M. Lundeberg, E. A. A. Pogna, L. Banszerus, Z. Mics, M. Massicotte, P. Schmidt, D. Davydovskaya, D. G. Purdie, I. Goykhman, G. Soavi, A. Lombardo, K. Watanabe, T. Taniguchi, M. Bonn, D. Turchinovich, C. Stampfer, A. C. Ferrari, G. Cerullo, M. Polini, F. H. L. Koppens. Nature Nanotechnology (2017).

DOI: 10.1038/s41565-017-0008-8

Media Contact

Sian Fogden
press@graphene-flagship.eu
44-012-237-62418

 @GrapheneCA

http://graphene-flagship.eu 

Sian Fogden | EurekAlert!

More articles from Materials Sciences:

nachricht Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern
20.07.2018 | Princeton University

nachricht Relax, just break it
20.07.2018 | DOE/Argonne National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>