Hot nanostructures cool faster when they are physically close together

June 1, 2015, US Department of Energy
Hot nanowires emit lattice vibrations known as phonons into underlying materials. When closely packed, phonon collisions can more efficiently transport heat away. Credit: Kathy Hoogeboom-Pot and the Kapteyn/Murnane Group

A complete description of nanoscale thermal transport is a fundamental problem that has defied understanding for decades. Here, researchers uncover a new regime of thermal transport near nanoscale structures, where counterintuitively, nanoscale hot spots cool more quickly when placed close together than when they are widely separated.

This finding suggests new approaches for addressing the significant challenge of heat management in nanosystems, with design implications for integrated circuits, thermoelectric devices, nanoparticle-mediated thermal therapies, and nanoenhanced photovoltaics for improving clean-energy technologies.

A great challenge in the semiconductor and electronics industries is that as nanoscale features get smaller and processes get faster, significant amounts of heat need to be quickly carried away from the nanostructures. A team from JILA, University of Colorado, and Lawrence Berkeley National Laboratory made a counter-intuitive discovery – it is much easier to cool nanostructures when they are arranged closely together rather than far apart. This result is exciting for the field of because in 2010 the same team showed that small, isolated hotspots are, in fact, quite challenging to cool. In the current experiments, the team patterned an array of nanostructures on different materials. When the nanostructures were heated with an infrared laser, they emitted phonons (lattice vibrations), which traveled into the substrate and collided with other phonons, carrying away the heat.

When the nanostructures were placed close together, cooling was more efficient because it did not matter whether the interacting phonons came from the same large hot nanostructure or neighboring small hot nanostructures. Thus, paradoxically, arranging the hot more closely together actually enhanced heat dissipation. These experiments enabled the researchers to determine which carry heat away from a hot region and also to predict new ways to engineer the cooling rate in a material.

Explore further: Graphene meets heat waves

More information: "A new regime of nanoscale thermal transport: Collective diffusion increases dissipation efficiency." PNAS Early Edition (2015) DOI: 10.1073/pnas.1503449112

"Measurement of quasi-ballistic heat transport across nanoscale interfaces using ultrafast coherent soft x-ray beams." Nature Materials 9, 26 (2010). DOI: 10.1038/nmat2568

Related Stories

Graphene meets heat waves

March 6, 2015

EPFL researchers have shed new light on the fundamental mechanisms of heat dissipation in graphene and other two-dimensional materials. They have shown that heat can propagate as a wave over very long distances. This is key ...

New way to cool micro-electronic devices

May 18, 2015

(—A team of researchers working at the University of Grenoble has developed a new way to cool solids at the micro level. In their paper published in Physical Review Letters, the team describes how they used laser ...

Tiny tool measures heat at the nanoscale

February 27, 2014

How heat flows at the nanoscale can be very different than at larger scales. Understanding how surfaces affect the transport of the fundamental units of heat, called phonons, could impact everything from thermoelectric materials ...

Large wave-vector phonon modes in silicon nanomembranes

July 16, 2013

( —Modified large wave-vector phonons in semiconductor membranes via hard X-ray thermal diffuse scattering (TDS) were observed that provide new insight into the fundamental thermal and electronic properties of ...

Recommended for you

Earth's deep mantle flows dynamically

March 25, 2019

As ancient ocean floors plunge over 1,000 km into the Earth's deep interior, they cause hot rock in the lower mantle to flow much more dynamically than previously thought, finds a new UCL-led study.

Scientists solve mystery shrouding oldest animal fossils

March 25, 2019

Scientists from The Australian National University (ANU) have discovered that 558 million-year-old Dickinsonia fossils do not reveal all of the features of the earliest known animals, which potentially had mouths and guts.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.