Quasi-ballistic thermal transport from a nanoscale hotspot observed using ultrafast coherent extreme ultraviolet beams

ORAL

Abstract

We study thermal transport from a nanoscale hotspot into a bulk material using ultrafast, coherent, extreme ultraviolet beams. When the size of the hotspot is smaller than the mean free path of the energy-carrying phonons in the substrate, we measure a decrease in energy transport compared with the diffusive Fourier law prediction. This is the first observation and quantitative measurement of quasi-ballistic thermal transport from a nanoscale heat source. Our results show that the Fourier law can be corrected to describe energy dissipation from nanostructures into the bulk by introducing a size-dependent ballistic thermal resistance. This finding could have significant impact on the thermal management and reliability of emerging nanoscale devices, and nano-enabled energy systems.

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Authors

  • Qing Li

    JILA, University of Colorado at Boulder

  • Mark Siemens

    JILA, University of Colorado at Boulder, JILA, National Institute of Standards and Technology, and University of Colorado, Deparment of Physics and JILA, University of Colorado at Boulder

  • Ronggui Yang

    Department of Mechanical Engineering, University of Colorado at Boulder, Department of Mechanical Engineering, University of Colorado, Boulder CO

  • Keith Nelson

    Department of Chemistry, MIT, Department of Chemistry, Massachusetts Institute of Technology, Cabridge MA

  • Erik Anderson

    Lawrence Berkeley Labs and Center for X-Ray Optics, Center for X-ray Optics and Lawrence Berkeley Laboratories, Berkeley CA

  • Margaret Murnane

    JILA, University of Colorado at Boulder

  • Henry Kapteyn

    JILA, University of Colorado at Boulder, Deparment of Physics and JILA, University of Colorado at Boulder